11institutetext: OAS-Bologna, Via P. Gobetti 101, 40129 Bologna, Italy
11email<EMAIL_ADDRESS>22institutetext: IASF-Milano, Via Corti 12,
20133 Milano, Italy 33institutetext: Instituto de Astrofísica, Facultad de
Ciencias Exactas, Universidad Andrés Bello, Fernández Concha 700, Las Condes,
Santiago RM, Chile 44institutetext: IAPS-Roma, Via Fosso del Cavaliere 100,
00133, Roma, Italy 55institutetext: School of Physics and Astronomy,
University of Southampton, Southampton SO17 1BJ

# Update of the INTEGRAL/IBIS AGN catalogue: deeper on the Galactic plane and
wider beyond

A. Malizia  L. Bassani 11 R. Landi 11 M. Molina 11 N. Masetti 22 E. Palazzi
1133 G. Bruni 11 A. Bazzano 44 P. Ubertini 44 A. J. Bird 44 55

( Received ; accepeted)

In this work we have updated the list of AGN detected by INTEGRAL taking into
account the new objects listed in the last published INTEGRAL/IBIS survey. We
have collected 83 new AGN increasing the number of INTEGRAL detected active
galaxies (436) by 19%. Half of these new additions are located behind the
Galactic plane; for most of them we have full X-ray coverage obtained through
archival data from Swift/XRT, XMM-Newton and NuSTAR. This allowed us to
associate each high-energy emitter with a single or multiple X-ray
counterpart/s and characterise the spectral shape of these new AGN by
estimating the photon index, the intrinsic absorption and the 2–10 keV flux. A
few cases where two soft X-ray counterparts fall within the INTEGRAL error
circle and at least one is classified as an AGN have been found and discussed
in detail. Thirty-four sources originally listed as AGN candidates or
unidentified objects have been recognised as AGN by employing three diagnostic
tests: WISE colours, radio emission and morphology. For 12 sources, among the
34 AGN candidates, we reduced optical spectra and confirmed their AGN nature,
providing also their optical class and redshift. This paper is part of an on-
going effort to keep the INTEGRAL AGN catalogue updated in order to provide
the scientific community with a hard X-ray selected sample of active galaxies
well classified and spectrally characterised.

###### Key Words.:

X-rays: galaxies – galaxies: active – galaxies: Seyfert

##  1 Introduction

In the last decades the science of Active Galactic Nuclei (AGN) has made great
progress which has led to a deep knowledge of both their population in the sky
and the physical mechanisms responsible for their emission over the entire
electromagnetic spectrum. One of the most important results recently proven is
the connection between the super massive black hole (SMBH) which powers the
AGN, and the host galaxy, the so-called feeding and feedback cycle of active
galaxies. But, although the co-evolution AGN-host galaxy scenario is widely
accepted and supported by clear observational evidence (Kormendy & Ho, 2013;
Heckman & Best, 2014), there are still some issues to be addressed mostly
regarding AGN feedback (e.g. Fabian 2012). What is certain as demonstrated by
deep X-ray observations, is that most SMBHs at galaxy centres grow hidden by
dust and gas (see e.g. Hickox & Alexander 2018 for a review).

Meanwhile at small scales closer to the SMBH, the standard simplistic picture
of the AGN unified model (Antonucci, 1993) is now outdated. According to this
theory, most of the amount of obscuring material mainly resides in the torus
which is also solely responsible for AGN classification. Actually the present
view of AGN is much more complex. Absorption has been revealed to be on
different scales/structures, winds, outflows, jets and of different nature,
neutral or/and ionised (see Ramos Almeida & Ricci (2017) for a review); the
absorbing torus itself has a structure not yet well understood (Zhao et al.,
2021), and nor is its connection to its surroundings (e.g. Netzer 2015).

Therefore absorption is proven to be a fundamental key both for the
understanding of the geometry of the innermost part of the AGN and for
feedback with the host galaxy. The most efficient way to study absorption and
address these still open issues, is to have large samples of AGN selected in
the hard X-ray band ($>$ 20 keV) which is far less biased towards absorption.
Since the early 2000s both INTEGRAL/IBIS (Ubertini et al., 2003) and Swift/BAT
(Barthelmy et al., 2005), thanks to their good sensitivity and wide-field sky
coverage in the high-energy domain (14-200 keV), have provided a remarkable
improvement in our knowledge of the high-energy extragalactic sky by detecting
more than 2000 (mostly local) AGN. It is worth noting that, due to its
observational strategy, Swift/BAT performs a nearly uniform all-sky survey and
so it is more effective at higher Galactic latitudes. INTEGRAL, on the other
hand, provides a sky survey with exposures that are deeper in the Galactic
plane and Galactic centre regions. INTEGRAL has also a higher angular
resolution, which is essential in these crowded regions. This makes the two
observatories fully complementary also in the case of extragalactic studies;
INTEGRAL surveys were particularly important in detecting highly absorbed AGN
along the Galactic plane. The area comprised between $\pm$10-15 degrees above
and below the Galactic plane, the so-called ”Zone of Avoidance”, is rich of
gas and dust which obscure starlight and screen nearly all background
extragalactic objects from traditional optical-wavelength surveys (in the
optical, as much as 20% of the extragalactic sky is obscured by the Galaxy).
As a consequence, historically the Galactic plane has not been a focus for
extragalactic astronomy before the advent of INTEGRAL. Hard X-rays ($>$10 keV)
are able to penetrate this zone providing a window that is virtually free of
obscuration relative to optical wavelengths and partly also to soft X-rays.
The capabilities of INTEGRAL/IBIS in studying extragalactic sources were
revealed soon after the launch of the satellite. It became soon evident that
the population of AGN emitting above 20 keV was growing thanks to the
discovery that many of the new hard X-ray detected sources (IGR sources) were
indeed active galaxies. In the first IBIS survey (Bird et al., 2004), based on
the first year of INTEGRAL observations, there were listed only 5 AGN which
became 33 (almost 20% of the entire catalogue) in the second survey (Bird et
al., 2006). Since 2004, a sequence of IBIS all-sky survey catalogues (Bird et
al. 2016 and references therein) as well as deep surveys of the Galactic
centre region and Galactic plane (Revnivtsev et al., 2004, 2006; Krivonos et
al., 2007, 2012, 2017) have been published at regular intervals, making use of
an ever increasing dataset. As the total number of known or newly discovered
AGN grew, it was possible to assemble them for population studies as we have
done over the years (Malizia et al., 2012, 2016, 2020a). So far the number of
AGN listed in this dataset amounts to 436 objects.

Taking advantage of the hard X-ray selection, this large sample of AGN has
been exploited to carry on several studies on relevant issues of extragalactic
science such as the possibility to identify highly obscured AGN like Compton
thick sources more easily (Malizia et al., 2007). It also allowed to tighten
the constraints on the absorption properties of the local AGN population,
finding that the true fraction of Compton thick AGN is $\sim$ 20% (Malizia et
al., 2009b). Furthermore, broad-band spectral (0.2–100 keV ) analysis of a
complete sample of Seyfert 1 galaxies, allowed Malizia et al. (2014) to
constrain for the first time the value of the high-energy cut-off at around
100 keV, clearly indicating that the primary continuum typically decays at
much lower energies than previously thought. Alongside INTEGRAL, Swift/BAT has
also contributed to these issues mostly confirming INTEGRAL results (Burlon et
al., 2011; Ricci et al., 2015, 2017; Kamraj et al., 2022).

Given the scientific relevance of the above results, it is fundamental to keep
updating these AGN high energy catalogues. The last INTEGRAL all-sky survey by
Krivonos et al. (2022) collects all the INTEGRAL observations over 17 years
until January 2020, and lists 929 hard X-ray sources detected above the
4.5$\sigma$ threshold, of which 113 are reported as unclassified. In order to
update the catalogue of INTEGRAL AGN, in this work we have added from
Krivonos’ list the AGN which have not been reported as INTEGRAL detection
before; we have also searched for their soft X-ray counterparts in order to
study their spectral behaviour. Moreover, we have tried to pinpoint, among
unidentified sources, those likely to be AGN on the basis of diagnostic
indicators such as WISE colours, radio emission and indication of extension in
the optical images, we have also classified 12 among AGN candidates by
analysing their optical spectra.

##  2 New AGN, the sample

The aim of this work is to update the list of AGN detected by INTEGRAL taking
into account the new active galaxies already listed in the Krivonos et al.
(2022) survey. We have collected 83 new AGN listed in Table LABEL:tab1, among
these 4 sources have already been listed in Malizia et al. (2016) as AGN
candidates and reanalysed here in order to be optically classified; 3 objects,
highlighted in bold in the table, are from Bird et al. (2016); 34 objects are
unclassified AGN, of which 22 have been already proposed as AGN candidates,
while the rest, 12, are unidentified objects in the Krivonos et al. (2022)
survey and have been classified or proposed as AGN in the present work (see
section 4). In Fig. 1 the entire INTEGRAL AGN sample so far collected is shown
with the different classes differentiated (see figure caption). The last
additions have been highlighted with filled symbols. As clearly seen from Fig.
1 the new AGN collected in this work (filled symbols) well reside in the
parameter space of the INTEGRAL AGN sample (see AGN review by Malizia et al.
2020b), but what it is worthy of note is that a large fraction of them are
located on the Galactic plane. In Fig. 2 the entire sample of INTEGRAL AGN are
plotted in the sky; the stars are the AGN reported in previous catalogues
(Malizia et al., 2020a, 2016, 2012), while the circles are the 83 AGN
collected in this work. It is evident that a large number of the new additions
are located in the plane of the Galaxy: 43% of the sample are within $\pm$10
degrees above and below the Galactic plane; the percentage rises to almost
half of the sample ($\sim$50%) within $\pm$15 degrees.

We have been able to obtain full X-ray coverage of almost the entire sample by
making use of data from Swift/XRT, XMM-Newton and NuSTAR archives. Only for
two objects, IGR J06380-7536 and RX J1317.0+3735, there are no 2-10 keV data
available but only a soft X-ray flux from the XMM-Slew Survey (Saxton et al.,
2008). 2-10 keV data have been used to associate the high-energy emitter with
a single or multiple X-ray counterpart/s, getting a better (arcsec) position.
For the counterpart search we have adopted the positional uncertainties quoted
by Krivonos et al. (2007) (see next section); hard/bright X-ray sources have
been favoured over soft/dim objects. The soft X-ray data have also been used
to characterise the high-energy source at low energies. Unfortunately in most
cases the statistically quality of the 2–10 keV data is poor and therefore we
have employed a simple model consisting of an absorbed power law which allowed
us to estimate the main spectral parameters such as the intrinsic
absorption111the Galactic absorption has been always considered and the 2–10
keV flux (e.g. Malizia et al. 2016).

In Table LABEL:tab1 we have listed the new AGN together with their essential
information as always reported in our catalogues: alternative names (column
2), the most precise coordinates RA and Dec (columns 3 and 4) from optical or
soft X-rays (Chandra or Swift/XRT), redshift (column 5), optical class taken
from NED, Simbad archives or Véron-Cetty & Véron (2010) (column 6). The X-ray
spectral parameters reported in this work are: column density, photon index
and 2-10 keV flux (columns 7 - 9); the hard X-ray flux (20-100 keV, column 9)
has been extrapolated from Krivonos et al. (2022). In column 11 the reference
for the 2-10 keV spectral parameters is given if not provided by the data
analysis performed for the first time in the present work.

Figure 1: Observed hard X-ray (20-100 keV) luminosity versus redshift for the
whole INTEGRAL AGN sample. Blue squares are broad line AGN, gold circles are
narrow line AGN, and light blue triangles are blazars. Red stars are AGN
candidates still unclassified for which a measure of redshift is available.
The filled symbols referred to the new AGN added in this work. Figure 2: All
the AGN detected so far by _INTEGRAL/IBIS_ plotted on the sky. The circle
represent the 83 new active galaxies studied in this work, while the stars are
the AGN detected in previous surveys and reported in Malizia et al. (2012,
2016, 2020a)

##  3 Cases with multiple counterparts

In this new sample of AGN detected by INTEGRAL we have found a few cases where
two soft X-ray counterparts fall within the INTEGRAL error circle and at least
one is classified as AGN. These objects are discussed individually in the
following sub-sections. In this work, following Krivonos et al. (2007), we
have used a 4.2 arcmin search radius (90% confidence level for a source
detected at 5 - 6 standard deviations) or, in case of no detection of a
counterpart, a 6.5 arcmin (99%), to search for possible X-ray counterparts.
Only counterparts coincident with well defined active galaxies are reported in
Table LABEL:tab1, while other potential associations are briefly described in
this section. In the Appendix we show the Swift/XRT 0.3-10 keV images of
sources discussed below. It is worth noting that in those cases where both
sources are detected above 3 keV, the hard X-ray emission detected by INTEGRAL
and reported in Krivonos et al. (2022) has to be considered as the combination
of the two sources, therefore in column 9 of Table LABEL:tab1 only estimates
of 20-100 keV fluxes have been provided.

###  3.1 IGR J04288-6702 also SWIFT J0428.2-6704 A/B

In the case of IGR J04288-6702 (see Fig. 5, left panel) we find two objects
emitting above 3 keV which are both outside the 90% (filled circle) but inside
the 99% (dashed circle) IBIS positional uncertainty: one (#1) is the Seyfert
1.5 galaxy LEDA 299570 reported in the Table LABEL:tab1 and also reported in
Krivonos et al. (2022), while the other one (# 2) at $\sim$11.5 arcmin, is the
Galactic source SXPS J042749.2-670434 (RA(J2000) = 04 27 49.63, Dec(J2000)=
-67 04 34.8), also reported as a Fermi/LAT source, 4FGL J0427.8-6704 (see
dashed-dotted error ellipse in Figure 5, left panel). The latter object is
associated with an eclipsing low mass X-ray binary (P = 8.8 hr) with a main-
sequence donor and a neutron-star accretor (Strader et al., 2016; Marchesini
et al., 2020). The X-ray light curve also shows properties similar to those
seen among known transitional millisecond pulsars: short-term variability, a
hard power-law spectrum ($\Gamma$ $\sim$ 1.7), and a comparable 0.5-10 keV
luminosity (2.4 $\times$1033 erg s-1). The source is furthermore remarkable
for its face-on inclination in the range 5∘-8∘, depending on the neutron star
and donor mass (Britt et al., 2017). Moreover, a gamma-ray eclipse having the
same phase as the optical one has been recently reported together with an
X-ray eclipse (Kennedy et al., 2020). This is clearly a very interesting
object which deserves further studies especially in the hard X-ray band.
NuSTAR, having an angular resolution better than IBIS, can allow us to
discriminate and study both these two sources.

###  3.2 PKS 0440-00 and 1RXS J044229.8-001823

In the right panel of Fig. 5 we show a very peculiar case as two blazars fall
within the IBIS error circle: PKS J044-00 also known as QSO B0440-003 (#1), a
flat spectrum radio quasar at z=0.845 and 1RXS J044229.8-001823, also known as
2MASS J04423023-0018294 (#2), a BL Lac object at z=0.449. For this reason it
is incorrect to quote PKS 0044-00 as the only INTEGRAL detection as listed in
Krivonos et al. (2022) survey catalogue; we suggest instead that this source
should be called IGR J04426-0018, since its emission is the merger of two
objects. The QSO is also detected up to the GeV band by Fermi/LAT and reported
as 4FGL J0442.6-0017 (Ajello et al. 2020, see dashed-dotted error ellipse in
the figure) in the fourth AGN catalogue, while the BL Lac, originally
indicated in the third Fermi catalogue as possible counterpart, has been
excluded in latest one. However, the BL Lac object is listed in the 3HSP
catalogue of high synchrotron-peaked blazars (Chang et al., 2019), showing a
synchrotron peak at around 2 $\times$1016 Hz. To estimate the 20-100 keV flux
of each source, we assumed an equal share of emission as implied by the almost
equal flux at soft X-ray energies and a similar spectral shape at X-ray
energies. Also this would be an interesting sky field to be pointed by the
NuSTAR telescope.

###  3.3 SWIFT J0835.5-0902

As evident in the XRT image shown in Fig. 6 (left panel), here too we find two
hard X-ray emitters associated with a single INTEGRAL/BAT source, although a
unique identification is provided in the 157-month Swift/BAT catalogue (Oh et
al., 2018). The first object (#1), the one reported in Table LABEL:tab1, is
located at RA(J2000) = 08 35 33.34 and Dec(J2000) = 09 05 30.2 (3.5 arcsec
X-ray positional uncertainty) and associated with the extended infrared object
2MASX J08353333-0905302. This galaxy is reported in Simbad with no redshift,
while NED provides a photometric redshift of z=0.1124. The WISE colours, W1-W2
= 0.86 and W2-W3 = 2.87, are typical of AGN (Secrest et al., 2015); the source
is listed in the UV-bright QSO survey of Monroe et al. (2016) and it is also
identified with an active galaxy from multi-waveband analysis (Edelson &
Malkan, 2012). The lack of intrinsic absorption in the X-ray spectrum
indicates that this is most likely a broad line AGN.

The other counterpart (#2), located at RA(J2000) = 08 35 31.5, Dec(J2000) =
-09 04 18.6 (3.8 arcsec X-ray positional uncertainty), is a Galactic source.
It is also reported as an XMM Slew source with 0.2-12 keV flux in the range
2.4-3.6 $\times$10-12 erg cm-2 sec-1. The XRT spectrum is well fitted by a
power law with photon index of 1.24$\pm 0.27$ and a 2-10/0.2-12 keV flux of
8.1$\times$10-13/1.2$\times$10-12 erg cm-2 s-1, lower than that measured by
XMM-Newton. The source is associated with the variable star ASAS
J083531-0904.1222https://www.aavso.org/vsx/index.phpview=detail.top&oid=281217,
classified as a rotating variable at a distance of 4.3 Kpc (GAIA parallax) and
with a possible period of 171.2 day. However, it is worth noting that in the
GAIA colours versus absolute magnitude diagram (BP-RP=2.1, absolute magnitude
= -1.83) the source is located in the region populated by eclipsing binaries.
It would be interesting to study this source further in order to unveil its
true nature and its contribution to the overall IBIS emission.

###  3.4 IGR J12418+7805

Another interesting case is IGR J12418+7805, where possibly two objects
contribute to the overall emission seen by INTEGRAL but, unfortunately, no
Swift/XRT observation is available. We found one source lying within the IBIS
error circle, which is clearly reported as an X-ray emitter both in the ROSAT
Bright Source (Voges et al., 1996) and in the XMM Slew Survey (Saxton et al.,
2008), and is therefore listed in Table LABEL:tab1. The source is associated
with the galaxy LEDA 140000 at a redshift of z=0.022, which is classified as a
Seyfert 1.9 in the Véron-Cetty & Véron (2010) catalogue and has a 0.2-12 keV
flux of 2.1 $\times$10-12 erg cm-2 sec-1. Assuming a typical value 1.8 for the
power law photon index, we have extrapolated the 2-10 keV flux value reported
in Table LABEL:tab1.

The other source, reported only in the XMM Slew Survey catalogue, is at $\sim$
2.2 arcmin distance from the previous one and is located at RA(J2000) = 12 43
13.8, Dec(J2000) = +78 08 28, with an associated positional uncertainty of
$\sim$10 arcsec. It is brighter than LEDA140000 with a 0.2-12 keV flux of 6
$\times$ 10-12 erg cm-2 sec-1; the source class is unclear, although its
location at high-galactic latitude suggests an extragalactic nature. The two
XMM Slew sources were detected at different epochs, almost 1 year apart, and
no radio, infrared nor optical association could be found within the XMM Slew
positional uncertainty of the second source. Only enlarging its positional
uncertainty to 15 arcsec, it is possible to find a WISE source with W1-W2=0.47
and W2-W3=4.04, which are more typical of starburst galaxies than AGN (Jarrett
et al., 2017). Due to these uncertainties, we decided not to list this second
source among the current INTEGRAL AGN update, waiting for a more sensitive
hard X-ray image of this sky region to confirm its contribution to the overall
INTEGRAL emission.

###  3.5 SWIFT J1937.5-4021

SWIFT J1937.5-4021 is reported as an unidentified object in the Krivonos et
al. (2022) list but we found that the most likely soft X-ray counterpart for
both IBIS and BAT detection is the XRT source located at RA(J2000) = 19 37
13.47 and Dec(J2000) = -40 16 14.84 (3.6 arcsec error radius), detected at
27$\sigma$ in the 0.3-10 keV band (20$\sigma$ above 3 keV) and well inside the
IBIS error circle (see source #1 in Fig. 6, left panel). This X-ray source is
also reported as an XMM Slew source with a 0.2-12 keV flux of 1.37
$\times$10-12 erg cm-2 s-1 and associated with the galaxy LEDA 588288 with
z=0.075 in the Simbad archive but reported in NED with a photometric redshift
of z=0.055776. Our analysis of the X-shooter optical spectrum of this source
allowed us to confirm its nature, classifying it as Seyfert 2 galaxy, and
measure its true redshift of z=0.0193 (see section 4.2).

The other possible counterpart, although outside the 90% but inside the 99%
IBIS error circle, is associated with the ROSAT source 1RXS J193716.1-401026,
located at RA(J2000) = 19 37 14.70 and Dec(J2000) = -40 10 14.91 (3.64 arcsec
positional uncertainty). Swift/XRT detected this source at 23$\sigma$ in the
0.3-10 keV band (9$\sigma$ above 3 keV). As evident from Fig. 6 (right panel)
both sources are well inside the 90% BAT error circle (dotted circle). We
suggest for 1RXS J193716.1-401026 an extragalactic origin since GAIA does not
detect a significant parallax or proper motion (Liao et al., 2019); moreover,
the observed WISE colours (see section 4.1) are typical of AGN. Both XRT
detections are hard X-ray sources, confirming that both can contribute to the
high-energy emission seen by IBIS.

###  3.6 AX J2254.3+1146 also SWIFT J2254.2+1147 A/B

This is another case where two AGN fall within the IBIS positional
uncertainty, although one is well inside the error circle while the other is
just at its border but inside the 99% error circle (see Fig. 7). Both sources
are well detected above 3 keV, they have similar redshifts but no interaction
is evident between the two. The first object (#1), UGC 12237, is a Seyfert 2
galaxy, while the other (#2) is a Seyfert 1 (UGC 12243) according to Véron-
Cetty & Véron (2010); both AGN are hosted in edge on galaxies of 0.24 and 0.34
axial ratio (major over minor axis), respectively. This is also an interesting
set of sources to be observed with the NuSTAR observatory in order to study
both AGN as already done for IGR J16058-7253 (Molina et al., 2021).

##  4 Unclassified objects

Thirty-four sources ($\sim$41% of the total sample) listed in Table LABEL:tab1
are unclassified AGN; 22 of them were already identified as active galaxies in
the Krivonos et al. (2022) survey, while the remaining 12 are reported as
unidentified sources and proposed as AGN candidates in this work. For this set
of 34 sources we have investigated their AGN nature by means of a two-step
approach. First we used multi-waveband information to asses their nature. In
particular, we made use of 3 diagnostics to confirm their nuclear activity:
WISE colours, detection of radio emission and other extragalactic features
such as location on the sky, measured redshift and optical morphology, i.e. we
have searched for indication of extension in their optical/near infrared
images.

As a second step, we searched public archives for optical spectra of these
unclassified sources, finding that 40% of the sample had indeed public data.
The results of this two-step approach are presented in the following sections.

###  4.1 Multiwaveband AGN signature: WISE colours, radio emission and other
features

It is now well established that WISE colours W1-W2 and W2-W3, can be used to
select AGN, or more specifically, efficiently accreting objects. AGN are
typically located in a well-defined region of the WISE colour-colour diagram,
i.e. in a region limited by W1 $-$ W2 ¿ 0.5 and 2 ¡ W2 $-$ W3 ¡ 5.1 (see
Secrest et al. 2015 for more details on the boundary delimitation). We have
therefore collected WISE colours for all the unclassified objects in order to
confirm their extragalactic nature. For this task we have used the ALLWISE
catalogue (Mainzer et al., 2014) which contains accurate positions, apparent
motion measurements, four-band fluxes and flux variability statistics for over
747 million objects detected on the co-added Atlas Images. For only one source
(IGR J19577+3339) not reported in the ALLWISE database, we used the
CatWISE2020 Catalogue (Marocco et al., 2021), which however lists only W1 and
W2 magnitudes and so provides only one infrared colour. Table LABEL:tab2 lists
the WISE colours of all unclassified sources while Fig. 3 shows the
corresponding positions in the WISE colour-colour diagram.

Besides the WISE colours, indication for the presence of an active nucleus
also comes from radio emission since almost all AGN detected so far by
INTEGRAL have a radio counterpart, which is not necessarily radio loud but can
emit at a few mJy level. We have therefore investigated the radio properties
of unidentified objects using as a first step old surveys radio catalogues,
more specifically, at 1.4 GHz, the National Radio Astronomy Observatories Very
Large Array Sky Survey (NVSS, Condon et al. 1998) and the Multi-Array Galactic
Plane Imaging Survey (MAGPIS, Helfand et al. 2006) while at 0.83 GHz the
Molonglo Telescope Surveys (SUMSS, Mauch et al. 2003) and MGPS-2 (Murphy et
al., 2007). These surveys are similar in sensitivity and spatial resolution
and cover together the whole sky, making them particularly well suited for
searching radio emission from our unclassified objects. However, their
sensitivity threshold is around the 10 mJy level, so that a number of sources
dimmer than this flux could not be detected. In these cases, we consulted more
recent all sky surveys like the VLA Sky Survery (VLASS, Gordon et al. 2021) at
3 GHz and the Rapid ASKAP Continuum Survey (RACS, McConnell et al. 2020) at
0.88 GHz. The radio fluxes obtained from all these surveys are listed in Table
LABEL:tab2, which also specifies the database used. Inspection of Table
LABEL:tab2 indicates that most objects are radio emitters, although the
majority have relatively weak fluxes, confirming in any case the presence of
an active nucleus at their centres. At the resolution of the surveys employed,
most of these detections correspond to a compact/single component morphology,
except for 4 objects which are displayed in Fig. 8 and Fig. 9 in the Appendix,
which show a more complex radio shape.

Finally, we adopted other extra-galactic indicators such as the knowledge of
the source redshift, the location above or below the Galactic plane or the
presence of extended emission typical of a galaxy morphology. The evidence of
source extension has been obtained from inspection of images provided by the
Dark Energy Camera optical and near-infrared survey (DECaPS, Schlafly et al.
2018) which, surveying the Galactic plane, is the most suitable for our
sources. A note related to the presence of a redshift or of extension in
optical images as well as an indication of the source location with respect
the Galactic plane is reported in the last column of Table LABEL:tab2.

In order to validate our AGN selection and definitely classify a source as an
AGN, we have adopted the criterion that at least 2 of the 3 diagnostics used
have to be satisfied.

As clearly shown in Fig. 3, WISE colour values point to an AGN nature for the
majority of the objects except for 7 of them, which are characterised by W1-W2
colours below the 0.5 line and W2-W3 below the 2 threshold as adopted by
Secrest et al. (2015). Five of the 6 sources with values below W1-W2 colour
threshold (IGR J03574-6602, IGR J06075-6148, IGR J06503-7742, IGR J16459-2325
and IGR J17255-4509) are however associated to galaxies with a measured
redshift while the only exception, IGR J16246-4556, is extended in the DECaPS
image. On the other hand, the only source above the W1-W2=0.5 line and outside
(although only marginally so) the W2-W3=2 boundary, is AX J1830.6-1002 which
is however a very puzzling case. As pointed out by Bassani et al. (2009), AX
J1830.6-1002 is an AGN located in the Galactic plane, inside a diffuse radio
supernova remnant. It is spatially coincident with a compact radio source
having the X-ray spectrum typical of a Compton thick AGN. Given the complexity
of its local environment and considering the uncertainties associated to the
WISE magnitudes, we do not consider this source as an outlier. Furthermore, it
is worth noting that all these 7 sources have radio detection with the
exception of IGR J16459-2325 for which only a RACS upper limit is available.

According to Secrest et al. (2015) the number of contaminating stellar objects
in their mid-IR AGN sample is very small, below 0.04%, making their selection
extremely reliable. Moreover, they quote their sample completeness to be
$\sim$84%, meaning that 16% of AGN are not selected using their method mainly
because they display a W1-W2 colour bluer than allowed, i.e. below the 0.5
line. Interestingly this is very close to the percentage of AGN (18%) we find
below W1-W2=0.5 both in the present sample or considering the entire set of
INTEGRAL AGN, where 507 out of 519 objects are listed in the ALLWISE
catalogue.

These unusual WISE colours are generally associated to heavily absorbed AGN as
pointed out by Gandhi et al. (2015) or to low luminosity AGN, for example
radiatively inefficient accretors, like LINERs as indicated by (Mingo et al.,
2016). In objects classified as LINERs the host galaxy dominates the mid-IR
emission with respect to the AGN moving them below the 0.5 threshold in the
W1-W2 versus W2-W3 diagram (Herpich et al., 2016)333Of the 29 Compton thick
AGN and 19 LINERs (or Seyfert/LINERs) present in entire AGN sample, 12 (or
41%) of the first and 10 (or 53%) of the second are located below the
W1-W2=0.5 line, suggesting that these two types of active nuclei have a far
greater chance than other AGN types to fall below the adopted threshold..

As can be seen from Table LABEL:tab1, the X-ray column densities of our 6
outliers indicate that 4 out of 6 objects are indeed absorbed with NH in
excess of 1023 cm-2, suggesting that the first hypothesis is a viable
explanation for their unusual WISE colours. However, as discussed in Sect.
4.2, the low luminosity AGN possibility turns out to be an equally valid
argument.

Figure 3: WISE colour/colour diagram of the 34 AGN candidates. The lines from
Secrest et al. (2015) is to delimit the area populated by AGN. Six sources
(IGR J03574-6602, IGR J06075-6148, IGR J06503-7742, IGR J16246-4556, IGR
J16459-2325 and IGR J17255-4509) have low W1-W2 values and need to be
investigated more deeply. The only source with W2-W3 below 2 is AX J
1830.6-1002, a very peculiar case.

As evident from values reported in Table LABEL:tab2, all our AGN candidates
have radio detections apart for 5 sources (IGR J04085-6546, IGR J14417-5533,
IGR J16459-2325, SWIFT J1839.1-5717 and SWIFT J1937.5-4021(2) which have not
been detected in the radio band and for which we were able to extract only
upper limits from RACS images. Nevertheless, for all these 5 sources, WISE
colours and morphology features point to an extragalactic nature and,
therefore, we are reasonably confident that our final AGN selection is correct
(see also following section).

It is worth noting that radio data analysis performed in this work was crucial
in unveiling the AGN nature of several objects as in the case of IGR
J19577+3339. This source is the only one with just one WISE colour and no
other diagnostic indicator of being extragalactic. IGR J19577+3339 is instead
a strong radio emitter (see Fig. 8, left panel in the Appendix) which is used
in the literature as a flat-spectrum radio quasar calibrator (Charlot et al.,
2020); a central bright component is visible in VLASS, with some additional
emission at about 5 arcsec towards NE and SW, most probably not correlated
with the source. Previous VLBI studies at 2.3 and 8.6 GHz (Pushkarev &
Kovalev, 2012) showed a bent jet on the pc-scale.

Another source for which the radio detection and radio morphology is decisive
to assess its AGN nature is IGR J08297-4250. As shown in Fig. 8 (right panel)
in the Appendix, it shows a core-jet like structure in RACS, reminiscent of a
blazar source although at a relatively low radio flux.

Finally, we note that two other objects, namely PKS 1413-36 and IGR
J16005-4645, show strong radio fluxes above the 1 Jy level; the first is
associated with a radio galaxy of large size (around 430 kpc, see Fig. 9 left
panel), while the second one is so far still morphologically unclassified
(although it is reported as extended in some surveys like ATCA, McConnell et
al. 2012) and poorly studied at radio frequencies. The RACS image of IGR
J16005-4645 (see Fig.9, right panel) shows a core+jet like structure, but,
combining data from various surveys, the radio spectrum is steep (-0.7/-1)
over the entire 0.150-20 GHz range. This suggests a large viewing angle and a
possible radio galaxy morphology with a lobe pointing towards us. We also note
that the radio and X-ray positions are displaced by roughly 28 arcsec, this
could be interpreted as a radio galaxy where the radio position refers to one
of the two lobes while the X-ray position coincides with the source core.
Alternatively, one must assume that the radio object is instead composed of
two sources not fully resolved in the radio image and associated with
different optical counterparts. Indeed, the radio central position is
compatible within errors with one weak GAIA EDR3 catalogue source (2020 VizieR
On-line Data Catalog: I/350) of unknown class. In any case, the X-ray source,
actually the secure counterpart of the INTEGRAL emitter, is likely an AGN not
only on the basis of its WISE colours and possible radio emission, but also
according to the SIX index developed by Edelson & Malkan (2012). This index
was empirically constructed by combing infrared colours over the 2-10 micron
waveband (to ensure an AGN like continuum) and the distance to the nearest
X-ray source. A value below zero of the resulting SIX index (-0.258 in our
case) indicates an object with a high likelihood (greater than 95$\%$) of
being an AGN.

###  4.2 Optical spectroscopy

For 12 sources, among the sample of 34 AGN candidates, we acquired reduced
optical spectra available in the 6dF444available at: http://www-
wfau.roe.ac.uk/6dFGS/form.html., PESSTO555available at:
https://www.eso.org/qi/catalogQuery/index/365. and X-Shooter666available at:
http://archive.eso.org/eso/eso_archive_main.html. databases and then analysed
them using IRAF 4777http://iraf.noao.edu/.. In the case of IGR J17255-4509,
SWIFT J1839.1-5717, and SWIFT J1937.5-4021 we stacked together the different
spectra to increase the signal-to-noise ratio. As a result, we found that
except for IGR J04085-6546, IGR J08297-4250, and SWIFT J1839.1-5717, all
sources show optical features which are typical of AGN. In order to provide a
classification, for these objects we examined the diagnostic ratio
([OIII]$\lambda$5007/Hβ and [NII]$\lambda 6583$/Hα) according to Ho et al.
(1993) and Kauffmann et al. (2003). The results of our findings are reported
in Table LABEL:tab3 where we list, for each source, the instrument used for
the optical observation, the line ratios used to determine the class, the
measured redshift and AGN class. In this work, we report for the first time
the optical class for 9 objects and the redshift value for 3 sources, namely
IGR J11275-5319, IGR J13045-5630, and IGR J16560-4958 (see Table LABEL:tab3);
for the remaining 6 galaxies, classified in this work, the redshifts we
estimated are compatible with values in the literature. Of the nine sources
with a clear optical class, 4 are LINERs and 5 are type 2 AGN. Interestingly,
all 4 LINERs fall below the AGN threshold line of 0.5 in the WISE colour-
colour diagram (Fig.3). Although a contribution from absorption cannot be
excluded, as already mentioned before, this could indicate that the unusual
WISE colours are due to radiatively inefficient accretion typically associated
with low luminosity objects like LINERs. As a further proof, we note that also
NGC 4102, the only other LINER object in the present sample, has WISE colours
(WI-W2=0.37 and W2-W3=4.1) that locate it in the same region of the diagram.
On the other hand, this suggests that also IGR J16246-4556 and IGR
J16459-2325, located below the AGN threshold in the WISE diagram of Fig. 3,
and for which no optical spectrum is available, could be LINERs. Most of these
LINERs are of type 2 with the possible exception of IGR J17255-4509, where a
broad HeI line has been detected in the near infrared spectrum (Ricci et al.,
2022) and indeed, as expected, most are absorbed in X-rays except for IGR
J17255-4509.

As we mentioned before, 3 objects deserve more in-depth discussion as their
optical spectra are somehow different to that expected from an emission line
AGN. The first source is IGR J04085-6546, associated with LEDA 310383:
although the diagnostics all point to an AGN, this source has been associated
with a transient event (OGLE 2013-SN-90) occurring on October 6, 2013
(Wyrzykowski et al., 2013), originating from a galaxy and lasting several
months. The follow-up PESSTO observation confirmed the AGN class of the event
(Spiro et al., 2013) despite the source photometric class pointed to a SN of
type I (Wyrzykowski et al., 2014). The XRT observation used for this work was
performed on Jan 3, 2013, after the peak of the transient event, while the
INTEGRAL measurements are the average of multi-years observations. Our
analysis of the PESSTO spectrum, shows the presence of broad Hα and Hβ
emissions and possibly a narrow [OIII]$\lambda$5007 emission line, at a
redshift z=0.116$\pm$0.001. However, since the spectrum was acquired about one
month after the announcement of the OGLE transient, we cannot exclude a
contribution from it, especially in the Hβ region. Nevertheless, we suggest a
Seyfert 1 AGN classification for this source.

Another interesting source is IGR J08297-4250. In this case the low S/N
X-Shooter spectrum does not allow us to infer the nature of this source.
However, the absence of emission and absorption lines, especially at z=0,
suggests this source is not a Galactic objects. The fact that the radio
morphology of the source is core plus jet like (see section 4.1 and Fig. 8,
right) seems to point to a BL Lac class; the absence of emission lines in the
optical spectra further validates this hypothesis and we therefore suggest
that IGR J08297-4250 is a BL Lac with unknown redshift. Although it is
difficult to discriminate blazars from other AGN types simply on the basis of
two mid-IR colours, this becomes possible with the use of the three-
dimensional WISE colour space, where a third colour, W3-W4, is also used (e.g
Fig 6 in D’Abrusco et al. 2019); this extra information also allows to
discriminate between blazar types, i.e. BL Lacs from Flat Spectrum Radio
Quasars. In the case of IGR J08297-4250, W3-W4 is 2.56, which locates the
source in the blazar region and well inside the BL Lac locus.

A more controversial case is that of SWIFT J1839.1-5717: also in this source
no emission lines are detected in the optical spectrum suggesting a similar
classification as for IGR J08297-4250. However we notice that Koss et al.
(2022), using the same optical spectrum, classify this source as a galactic
object, i.e. a star, given the detection of a CaII absorption line. The object
is located well below the Galactic plane, has WISE colours typical of an AGN
and not of a stellar object and its optical spectrum is characterised by a
smooth continuum with no apparent absorption lines at redshift z=0. This gives
us confidence to rule out the stellar nature for SWIFT J1839.1-5717 and given
the above results, also in this case we suggest the source classification as
an AGN, and more specifically as a BL Lac.

Figure 4: Log NH versus F${}_{2-10\leavevmode\nobreak\
keV}$/F${}_{20-100\leavevmode\nobreak\ keV}$ flux ratio for our sample
sources. Open circles are Seyfert 1-1.5 sources while filled circles are
Seyfert 2 sources. Triangles are blazars, filled squares are XBONG and stars
are LINERs. Lines correspond as in Malizia et al. (2007) to the expected
values for an absorbed power law with photon index 1.5 (dotted line) and 1.9
(dashed line).

##  5 Discussion and Conclusions

In this work we have added overall 83 objects to the previous INTEGRAL list of
AGN: more than 40% of them are in the zone of avoidance, i.e. behind our
Galaxy where INTEGRAL/IBIS exposure is much deeper than Swift/BAT. This
peculiarity makes the extragalactic nature of these objects more difficult to
establish, indeed most of the 34 objects not yet classified in the literature
and listed as AGN in Table LABEL:tab1, are on the Galactic plane ($\sim$68%).
For these 34 still unclassified sources we have used 3 diagnostics based on
far-infrared data, radio detection and redshift measurement, position in the
sky or extension in the optical images, in order to confirm their AGN nature.
At least 2 diagnostics are verified for all the 34 candidates and therefore we
can consider them AGN although of unknown class. Indeed we were also able to
classify 12 AGN among this set of candidates on the basis of public available
optical spectra, finding that 5 of them are Seyfert 2, 4 are LINERs; one
possible a Seyfert 1 galaxy (IGR J04085-6546) and two sources are possible BL
Lac blazars (IGR J08297-4250 and SWIFT J1839.1-5717). Due to their still
uncertain optical classes, we consider these last three objects as AGN
candidates. Interestingly, the hard X-ray selection samples all types of AGN
including the low luminosity ones. Indeed our sample lists 6 BL Lac objects
(plus 2 possible), 6 Flat Spectrum Radio QSO, 1 Narrow Line Seyfert 1 galaxy,
5 LINERs, 2 XBONG or X-ray Bright Optically Normal Galaxies, the rest are
Seyfert 1-1.5 (18) and Seyfert 1.8-2 (21).

As previously observed by Malizia et al. (2012), the optical classification is
generally reflected in the X-ray absorption properties of the sources, i.e.
type 1 objects and blazars are generally unabsorbed while type 2 sources are
mildly/heavily absorbed. A useful tool to identify outliers to this trend is
the diagnostic diagram shown in Fig. 4 as presented in Malizia et al. (2007)
where the source column density is plotted versus the soft to hard X-ray flux
ratio (see Malizia et al. 2007 for a full description of this diagnostic). In
this plot a clear trend of a decreasing softness ratio as the absorption
increases is visible, as expected if the 2 – 10 keV flux is progressively
depressed as the absorption becomes stronger. Outliers could be absorbed type
1 AGN with column density above 1022 cm-2, strongly variable sources
(Seyfert/blazar) where the soft and hard X-ray fluxes are not simultaneously
measured and Compton thick objects where the column density is not properly
estimated. Using the entire INTEGRAL AGN sample, we find that these outliers
are $\sim$10%; some objects belonging to each class of these outliers have
already been pinpointed and extensively discussed in previous works (see for
example Malizia et al. 2007, 2009a, 2012).

Most of the sources in the present sample follow the expected trend, except
for a few absorbed type 1 AGN (i.e. open circles (Seyfert 1-1.5) and triangles
(blazars) with column densities above 1022 cm-2) which fall in the region
populated by absorbed objects. Their peculiarity may be due either to an
incomplete account of the Galactic absorption especially in those AGN located
behind the Galactic plane (like for the two blazars 4C 50.11 and 4C 39.35) or
to a poor quality of the X-ray spectrum (like for Fairall 1203). In NGC 2617
and MKN 817 the unexpected absorption is likely due to their spectral
complexity: NGC 2617 is a changing look AGN with a complex X-ray absorption
structure/broad line region (Giustini et al., 2017; Yang et al., 2021); MKN
817 is also quite peculiar, since its absorption is likely ionised and
variable and probably interferes with the source disk–corona coupling (Miller
et al., 2021). A further anomalous case is that of AX J2254.7+1146(2)/UGC
12243, which as already discussed, is a type 1 AGN with no absorption but with
a very low soft to hard X-ray flux ratio. This could be due to strong
variability in the high energy emission so that combining soft and hard X-ray
data not taken contemporaneously, provides a false value of the flux ratio.
However, a comparison between XRT and XMM observations taken a few years
apart, does not indicate a change in the source flux within the errors. For
this reason, the source may have a highly absorbed soft X-ray spectrum which,
if not properly corrected for the true column density value, provides again a
wrong estimate of the flux ratio. In support of this last hypothesis we note
that Oh et al. (2022) classify UGC 12243 as a type 2 AGN contrary to previous
claim that it is a Seyfert 1 (Véron-Cetty & Véron, 2010). If this is true,
then UGC 12243 could be another local Compton thick AGN, but in order to
understand the true nature of this source, good quality X-ray observations are
clearly needed. As expected and visible in Fig. 4, none of the Seyfert 2 are
unabsorbed, although the column density in several sources is often quite mild
for a type 2 AGN.

Interestingly we do not find any Compton thick AGN although we would have
expected a few. Following Malizia et al. (2009b), 7% of objects below redshift
0.335 are expected to be Compton thick (i.e. around 5 sources in our sample);
more accurately Torres-Albà et al. (2021) estimate the fraction of Compton
thick objects with redshift below 0.05 to be 7.7% or 2-3 objects in our case.
This further confirms that also at high energies absorption can prevent the
detection of some heavily obscured sources as first reported in Malizia et al.
(2009b). However, the diagnostic plot reported in Fig. 4 shows a couple of
objects which have a too low softness ratio values for the observed column
densities, suggesting for them a Compton-thick nature; these are UGC 12243
(already discussed above) and the XBONG source IGR J05048-7340/ESO 33-11. In
this last case the optical classification as a normal galaxy could be due to
the nuclear emission being completely hidden by the absorption; in addition,
it must always be kept in mind that the poor quality of the X-ray spectral
data can cause a wrong estimate of the X-ray column density. This is another
interesting source that deserves more in depth studies.

The only Narrow Line Seyfert 1 reported in the sample is RX J1317.0+3735
(Rakshit et al., 2017), so far a poorly studied AGN; its black hole mass is
log (MBH)=6.88, while its Eddington ratio based on the 5100 Å monochromatic
luminosity is log Edd=-0.53 (Liu et al., 2019), confirming that this class of
AGN tends to have small black hole masses and high Eddington ratios (Rakshit
et al., 2017).

Five objects in the present sample are classified as LINERs plus two, IGR
J16246-4556 and IGR J16459-2325, likely to be LINERs candidates. Most of them
display narrow lines and can therefore be classified as type 2 AGN while only
one, IGR J17255-4509, likely belongs to the type 1 class. Their hard X-ray
luminosities range from 2 $\times$ 1041 erg s-1 to a few 1043 erg s-1.
However, a couple of them, despite occupying the lower part of the luminosity
versus redshift diagram (see Fig. 1), cannot be considered low luminosity AGN
due to their high luminosity. In addition, the Eddington ratios, available for
only a few objects, fall in the range 0.001-0.009 (Caramete & Biermann, 2010)
indicating again a behaviour much more similar to Seyfert galaxies. We
conclude that the hard X-ray emitting LINERs are definitely active galaxies
but whether their nucleus is similar or different from more canonical AGN is
still unclear. Finally, we note that the WISE colour-colour diagram could be
used to discriminate between LINERs and other AGN like Seyferts and blazars,
as amply discussed in section 4.1.

Of the reported blazars, all are MeV emitters being detected by Fermi/LAT,
with the only exceptions of IGR J01036-6439, IGR J04426-0018(2) and SWIFT
J0600.7+0008. Four blazars (SWIFT J0710.5+5908, RX J1136.5+6737, IGR
J20596+4303 and 1ES 2344+514) are also TeV sources and all of these are HBL or
high frequency peaked BL Lac. None of the two blazar candidates is a Fermi
source.

In this work we have added to the INTEGRAL AGN catalogue 83 new sources of
which more than 40% are located behind the Galactic plane; this highlights the
importance of INTEGRAL/IBIS in discovering new hard X-ray emitting AGN, mainly
in this zone of avoidance where it is much more difficult to discriminate
between galactic and extragalactic objects. Their Galactic plane location
makes the follow-up harder especially in the UV and optical bands, thus, the
importance of also using multiple diagnostic tests to properly classify each
object. In this paper we have shown that WISE colours, radio emission and
morphological evidences can be used as powerful diagnostic tests to identify
AGN candidates among high energy emitters.

## Acknowledgements

The authors acknowledge financial support from ASI under contract n.
2019-35-HH.0.

This research has made use of the NASA/IPAC Extragalactic Database (NED) and
NASA/ IPAC Infrared Science Archive, which are operated by the Jet Propulsion
Laboratory, California Institute of Technology, under contract with the
National Aeronautics and Space Administration. This work made use of
observations collected at the European Southern Observatory under ESO programs
0103.A-0521(A), 0102.D-0918(A), 0102.A-0433(A), and 0101.A-0765(A). The
authors thank the anonymous referee for the useful comments.

Table 1: AGN candidates | WISE colours | RADIO FLUX | Extra Data
---|---|---|---
Source | W1 - W2 | W2 - W3 | SUMSS | NVSS | Other | AGN marks
|  |  | (0.843GHz) | (1.4GHz) |  |
IGR J03574-6602 | 0.32 | 3.80 |  16.8$\pm$1.7 | – | – | z
IGR J04059+5416 | 0.82 | 2.82 | – | – |  1.92$\pm$0.30a | –
IGR J04085-6546 | 0.72 | 2.20 | – | – |  ¡33.0 c | z
IGR J06075-6148 | 0.37 | 3.45 |  52.3$\pm$3.6 | – | – | z
IGR J06503-7742 | 0.25 | 2.29 | – | – |  5.10$\pm$0.51c | z
IGR J08297-4250 | 0.54 | 3.09 | – | – |  4.81$\pm$0.48c | Ext
SWIFT J0835.5-0902 | 0.86 | 2.87 | – | – |  2.88$\pm$0.29c | z
SWIFT J0958.2-5732 | 1.14 | 2.28 |  13.2$\pm$1.9 | – | – | z
IGR J11275-5319 | 0.97 | 3.25 |  14.0$\pm$1.1 | – | – | z
IGR J11299-6557 | 1.18 | 3.04 | – | – |  5.98$\pm$0.60c | –
IGR J13045-5630 | 0.98 | 3.26 |  16.8$\pm$1.4 | – | – | –
PKS 1413-36 | 1.03 | 2.70 | – |  1098.2$\pm$34.3 | – | z
IGR J14417-5533 | 0.97 | 2.51 | – | – |  ¡0.84c | Ext
IGR J14557-5448 | 0.81 | 3.13 |  33.1$\pm$1.4 | – | – | –
IGR J16005-4645 | 1.22 | 2.64 |  7843.0$\pm$235.3 | – | – | –
IGR J16181-5407 | 1.18 | 2.57 | – | – |  10.5$\pm$1.00c | z
IGR J16246-4556 | 0.18 | 1.78 | – | – |  9.51$\pm$0.95c | Ext
IGR J16413-4046 | 0.95 | 2.86 | – | – |  2.23$\pm$0.22c | –
IGR J16459-2325 | 0.28 | 2.18 | – | – |  ¡0.99c | z
IGR J16560-4958 | 0.67 | 2.19 | – | – |  11.4$\pm$1.14c | Ext
IGR J17157-5449 | 0.86 | 2.87 | – | – |  7.09$\pm$0.71c | –
IGR J17255-4509 | 0.36 | 3.00 |  10.9$\pm$1.2 | – | – | z
IGR J18134-1636 | 0.74 | 3.49 | – | – |  1.98$\pm$0.40a | –
IGR J18141-1823 | 0.73 | 2.99 | – | – |  10.3$\pm$6.80b | –
AXJ 1830.6-1002 | 1.02 | 1.87 | – | – |  2.54$\pm$0.40a | –
SWIFT J1839.1-5717 | 1.84 | 3.47 | – | – |  ¡0.57c |  l$\leq$-20
IGR J18486-0047 | 1.72 | 2.68 | – |  20.6$\pm$1.7 | – | –
IGR J18497-0248 | 0.66 | 2.51 | – |  15.9$\pm$1.6 | – | –
IGR J19294+1328 | 0.89 | 2.57 | – | – |  3.42$\pm$0.30a | –
SWIFT J1937.5-4021-1 | 0.77 | 2.96 | – | – |  4.87$\pm$0.49c | z
SWIFT J1937.5-4021-2 | 0.81 | 2.40 | – | – |  ¡1.05 c |  l$\leq$-20
IGR J19504+3319 | 0.85 | 2.18 | – | – |  3.972$\pm$0.2a | –
IGR J19577+3339 | 0.8* | – | – |  295.2$\pm$8.9 | – | –
SWIFT J2055.0+3559 | 1.38 | 2.98 | – |  9.6$\pm$0.5 | – | z
a= VLASS; b = MAGPIS; c= RACS
Table 2: Confirmed AGN: optical spectra Source | Instrument |  Log(OIII$\lambda 5007$/Hβ) |  Log(NII$\lambda 6583$/Hα) |  Hα/Hβ | $z$ | class
---|---|---|---|---|---|---
IGR J03574-6602 | X-shooter | 0.42 | -0.120 | 5.73 | 0.0190 | LINER
IGR J04085-6546 | PESSTO | - | - | - |  | Sy 1?
IGR J06075-6148 | 6dF | -0.014 | -0.350 | 2.88 | 0.0040 | LINER
IGR J06503-7742 | 6df | 0.057 | 0.511 | 12.64 | 0.0373 | LINER
IGR J08297-4250 | X-shooter | - | - | - |  | Blazar/BL Lac?
IGR J11275-5319 | X-shooter | 1.01 | -0.062 | 3.58 | 0.0503 | Sy 2
IGR J13045-5630a | X-shooter | 0.91 | -0.140 | 5.00 | 0.0511 | Sy 2
PKS 1413-36 | X-shooter | 1.00 | -0.313 | 3.75 | 0.0753 | Sy 2
IGRJ16560-4958a | X-shooter | 1.20 | 0.460 |  $>$10.77 | 0.0586 | Sy 2
IGR J17255-4509a | X-shooter | 0.80 | 0.002 | 10.40 | 0.0197 | LINER
SWIFT J1839.1-5717 | X-shooter | - | - | - | - | Blazar/BL Lac?
SWIFT J1937.5-4021 | X-shooter | 1.36 | 0.400 | 8.59 | 0.0740 | Sy 2
a = for this source we report the redshift estimate for the first time

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##  Appendix A New INTEGRAL/IBIS AGN

  * Notes: Sources in bold are (also) in cat 1000; values of Log NH in bold are for sources where only Galactic absorption is measured, for the rest of the sample sources the Galactic absorption has been always considered in addition to the intrinsic one listed; (†) 2-10 keV flux in units of 10-12 erg cm-2 s-1; (‡) 20-100 keV flux in units of 10-11 erg cm-2 s-1; (1) Two sources are present within the IBIS error circle: a Seyfert 1 galaxy, whose values are reported in the table, and an eclipsing X-ray binary, a transitional millisecond pulsar (SXPS J042749.2-670434). Both sources are detected above 3 keV, therefore the hard X-ray emission could be due to the contribution of the two; (2) Two sources present within the IBIS error circle, both AGN, both reported in the table. The hard X-ray emission could be the result of the contribution of two objects and therefore the value reported in Krivonos has been divided by 2; (3) Two sources lie within the IBIS error circle: the galaxy 2MASX J08353333-0905302’ with the photometric redshift reported in the table, and a rotationally variable Star (ASAS J083531-0904.1). Both objects emit above 5 keV, therefore they could both contribute to the hard X-ray emission. (⋆) For this sources only the XMM Slew Survey flux is available; (4${}^{\star})$ Two sources are listed in the XMM Slew Survey: one is LEDA140000 (also ROSAT Bright) reported in the table, while the other, XMMSL2 J124313.8+780828 with a 2-10 keV flux of 5.9 $\times$ 10-12 erg cm-2 s-1, is unidentified. Probably, they both contribute to the high-energy emission; (5) Two sources lie within the IBIS error circle: one is the Seyfert 2 reported in the table while the second is a CV. They both contribute to the high-energy flux; ⋄ Mean value; ♣ Photometric redshift; ∗ Redshift and optical class from Oh et al. (2022);

  * References: 1): this work; 2): Yamada et al. (2021); 3): Ricci et al. (2017); 4): Tomsick et al. (2015); 7): Annuar et al. (2020); 8) Saxton et al. (2008); 9) Zhao et al. (2021); 10) Giustini et al. (2017); 11) Landi et al. (2017); 12) Clavel et al. (2019); 13) Rodriguez et al. (2010); 14) Kara et al. (2021); 15) Tomsick et al. (2020); 16) Landi et al. (2011); 17) Tomsick et al. (2012) 18) Bassani et al. (2009); 19) Rahoui et al. (2017); 20) Tomsick et al. (2021) 21) Karasev et al. (2020)

Table 3: INTEGRAL/IBIS AGN Name | altern. name | RA | dec | z | class |  Log NH | $\Gamma_{2-10\leavevmode\nobreak\ keV}$ |  F${}_{S}^{\dagger}$ |  F${}_{H}^{\ddagger}$ | Ref.
---|---|---|---|---|---|---|---|---|---|---
SWIFT J0001.6-7701 | Fairall 1203 | 00 01 46.08 |  $-$76 57 14.3 | 0.058 | Sy 1 |  22.69${}^{+0.10}_{-0.10}$ | 1.8 (fixed) | 3.39 | 0.72 | 1 (XRT)
NGC 235A | - | 00 42 52.81 |  $-$23 32 27.7 | 0.022 | Sy 2 |  23.71${}^{+0.06}_{-0.06}$ |  1.68${}^{+0.11}_{-0.10}$ | 2.10 | 4.76 | 2
IGR J00569+6359 | 3PBC J0056.9+6401 | 00 57 12.70 |  $+$63 59 53.2 | 0.291 | Sy 1.2 |  22.37${}^{+0.07}_{-0.08}$ |  1.79${}^{+0.21}_{-0.25}$ | 2.40 | 0.38 | 3
IGR J01036-6439 | PKS 0101-649 | 01 03 33.74 |  $-$64 39 07.7 | 0.163 | Blazar/QSO | 20.41 |  1.66${}^{+0.08}_{-0.06}$ | 3.00 | 1.12 | 3
IGR J01242+3348 | NGC 513 | 01 24 26.80 |  $+$33 47 58.2 | 0.020 | Sy 2 |  22.72${}^{+0.04}_{-0.05}$ |  1.47${}^{+0.07}_{-0.07}$ | 3.89 | 1.68 | 1 (XMM + NuSTAR)
SWIFT J0238.2-5213 | ESO 198-24 | 02 38 19.72 |  $-$52 11 32.3 | 0.045 | Sy 1 | 20.43 |  1.72${}^{+0.14}_{-0.11}$ | 12.9 | 1.38 | 3
SWIFT J0250.2+4650 | LEDA 2287192 | 02 50 27.18 |  $+$46 47 29.4 | 0.0210 | Sy 2 |  22.38${}^{+0.10}_{-0.09}$ |  1.36${}^{+0.28}_{-0.26}$ | 6.40 | 1.63 | 1 (XRT)
IGR J03574-6602 | NGC 1503 | 03 56 33.14 |  $-$66 02 27.6 | 0.019 | AGN |  $\sim$23.26 | 1.8 (fixed) | 0.34 | 0.75 | 1 (XRT)
SWIFT J0359.7+5058 | 4C 50.11 | 03 59 29.75 |  $+$50 57 50.2 | 1.520 | Blazar/QSO |  22.67${}^{+0.12}_{-0.10}$ |  1.47${}^{+0.20}_{-0.07}$ | 5.40 | 1.10 | 3
IGR J04059+5416 | 2MASX J04055765+5418446 | 04 05 57.66 |  $+$54 18 44.7 | – | AGN |  22.54${}^{+0.23}_{-0.34}$ |  1.50${}^{+0.90}_{-0.80}$ | 1.10 | 1.08 | 4
IGR J04085-6546 | LEDA 310383 | 04 08 38.82 |  $-$65 45 59.1 | 0.125 | AGN | 20.56 |  1.63${}^{+0.31}_{-0.30}$ | 1.31 | 0.67 | 1 (XRT)
SWIFT J0414.8-0754 | LEDA 14727 | 04 14 52.66 |  $-$07 55 39.7 | 0.038 | Sy 1 | 20.73 |  1.97${}^{+0.92}_{-0.27}$ | 5.00 | 1.79 | 3
NGC 1566 | - | 04 20 00.40 |  $-$54 56 16.6 | 0.005 | Sy 1 | 19.93 |  1.73${}^{+0.07}_{-0.06}$ | 3.10 | 2.20 | 3
SWIFT J0427.0+0734 | 2MASS J04270427+0716316 | 04 27 04.28 |  $+$07 16 31.7 | 0.096 | Sy 1 | 20.94 |  1.61${}^{+0.17}_{-0.17}$ | 4.20 | 0.83 | 1 (XRT)
IGR J04288-6702(1) | LEDA 299570 | 04 29 47.48 |  $-$67 03 18.9 | 0.065 | Sy 1.5 | 20.54 |  1.64${}^{+0.11}_{-0.11}$ | 1.78 | 0.68 | 1 (XRT)
IGR J04426-0018(2) | 1RXS J044229.8-001823 | 04 42 30.18 |  $-$00 18 29.1 | 0.449 | Blazar/BL Lac | 20.80 |  1.83${}^{+0.07}_{-0.07}$ | 1.39 | 0.42 | 1 (XRT)
IGR J04426-0018(2) | PKS 0440-003 | 04 42 38.59 |  $-$00 17 42.6 | 0.845 | Blazar/QSO | 20.80 |  1.92${}^{+0.09}_{-0.09}$ | 1.32 | 0.42 | 1 (XRT)
IGR J05048-7340 | ESO 33-11 | 05 05 06.27 |  $-$73 39 04.6 | 0.014 | XBONG | 20.15 |  1.8${}^{+0.3}_{-0.3}$ | 0.33 | 0.47 | 1 (XRT)
IGR J05162-1034 | MCG-02-14-009 | 05 16 21.22 |  $-$10 33 41.4 | 0.029 | Sy 1 | 20.97 |  2.23${}^{+0.05}_{-0.05}$ | 4.20 | 1.08 | 3
IGR J05511-1218 | LEDA 148076 | 05 51 13.12 |  $-$12 14 42.1 | 0.035 | XBONG |  22.93${}^{+0.32}_{-0.24}$ | 1.8 (fixed) | 0.8 |  $<$1.75 | 1 (XRT), 5, 6
SWIFT J0600.7+0008 | IRAS05581+0006 | 06 00 40.11 |  $+$00 06 18.4 | 0.115 | Sy 1.9 |  23.30${}^{+0.11}_{-0.11}$ | 1.8 (fixed) | 1.99 | 0.83 | 1 XRT
IGR J06075-6148 | ESO 121-6 | 06 07 29.85 |  $-$61 48 27.3 | 0.004 | AGN |  23.33${}^{+0.03}_{-0.03}$ |  1.89${}^{+0.08}_{-0.08}$ | 0.95 | 0.73 | 7
IGR J06380-7536 | LEDA 243576 | 06 37 43.17 |  $-$75 38 46.3 | 0.089 | Sy 1.8 | – | – | – | 0.78 | no (2-10) data
IGR J06503-7742⋆ | LEDA 235040 | 06 49 54.37 |  $-$77 42 18.6 | 0.037 | AGN | – | – | 0.64 | 0.94 | 8
IGR J07072-1227 | 2MASX J07071126-1227560 | 07 07 11.43 |  $-$12 28 00.2 | 0.071 | Sy 2 |  22.71${}^{+0.56}_{-0.35}$ | 1.8 (fixed) | 1.11 | 1.13 | 1 (XRT), 5
SWIFT J0710.5+5908 | RX J0710.5+5908 | 07 10 30.07 |  $+$59 08 20.3 | 0.125 | Blazar/BL Lac | 20.65 |  1.80${}^{+0.04}_{-0.04}$ |  28.5⋄ | 2.28 | 1 (XRT)
IGR J07328-4640 | PKS 0731-465 | 07 32 44.31 |  $-$46 40 17.2 | – | Blazar/QSO |  21.18${}^{+0.20}_{-0.28}$ | 1.8 (fixed) | 1.99 | 0.89 | 1 (XRT)
RX J0818.9-2252 | LEDA 80921 | 08 18 57.72 |  $-$22 52 36.2 | 0.035 | Sy 1 | 21.05 |  1.79${}^{+0.09}_{-0.09}$ | 3.46 | 0.93 | 1 (XRT)
SWIFT J0823.4-0457 | Fairall 272 | 08 23 01.10 |  $-$04 56 05.4 | 0.022 | Sy 2 |  23.23${}^{+0.05}_{-0.05}$ |  1.51${}^{+0.11}_{-0.08}$ | 6.46 | 2.22 | 9
IGR J08297-4250 | 2MASX J08294112-4251582 | 08 29 41.12 |  $-$42 51 58.3 | – | AGN |  23.78${}^{+0.43}_{-0.53}$ |  1.50${}^{+0.90}_{-0.80}$ | 1.10 | 0.67 | 4
SWIFT J0835.5-0902(3) | 2MASX J08353333-0905302 | 08 35 33.34 |  $-$09 05 30.2 |  0.112♣ | AGN | 20.62 |  2.04${}^{+0.13}_{-0.13}$ | 1.68 | 1.62 | 1 (XRT)
NGC 2617 | - | 08 35 38.00 |  $-$04 05 17.9 | 0.014 | Sy 1/1.8 |  23.34${}^{+0.07}_{-0.08}$ |  1.87${}^{+0.01}_{-0.01}$ | 23.5 | 5.00 | 10
PKS 0921-213 | - | 09 23 38.88 |  $-$21 35 47.1 | 0.053 | Sy 1 | 20.63 |  1.77${}^{+0.08}_{-0.08}$ | 6.23 | 1.60 | 1 (XRT)
SWIFT J0924.2-3142 | 2MASS J09235373-3141308 | 09 23 53.61 |  $-$31 41 31.6 | 0.042 | Sy 1.8 |  23.91${}^{+0.23}_{-0.27}$ | 1.8 (fixed) | 1.7 | 2.26 | 11
SWIFT J0958.2-5732 | WISEA J095834.97-572927.2 | 09 58 35.03 |  $-$57 29 26.7 | – | AGN |  22.28${}^{+0.07}_{-0.09}$ | 1.8 (fixed) | 3.44 | 0.52 | 1
ESO 317-41 | SWIFTJ1031.5-4205 | 10 31 23.11 |  $-$42 31 23.1 |  0.019∗ | Sey 2 |  23.90${}^{+0.07}_{-008.}$ |  1.76${}^{+0.31}_{-0.21}$ | 0.44 | 1.11 | 9
IGR J10447-6027 | 2MASS J10445192-6025115 | 10 44 51.91 |  $-$60 25 11.9 | 0.047 | Sy 2 |  23.22${}^{+0.07}_{-0.07}$ |  1.50${}^{+0.06}_{-0.06}$ | 2.20 | 0.95 | 12
IGR J10595-5125 | ESO 215-14 | 10 59 19.03 |  $-$51 26 32.3 | 0.019 | Sy 1 | 21.10 |  1.65${}^{+011.}_{-0.11}$ | 5.71 | 0.55 | 1 (XRT)
IGR J11275-5319 | 2MASX J11273392-5320270 | 11 27 33.90 |  $-$53 20 25.9 |  0.049♣ | AGN |  23.18${}^{+0.26}_{-0.22}$ | 1.8 (fixed) | 0.84 | 0.97 | 1 (XRT)
IGR J11299-6557 | 2MASS J11295643-6555218 | 11 29 56.90 |  $-$65 55 18.9 | – | AGN |  $<$22.04 |  2.09${}^{+0.98}_{-0.81}$ | 3.20 | 0.53 | 1 (XRT)
RX J1136.5+6737 | SWIFT J1136.7+6738 | 11 36 30.10 |  $+$67 37 04.0 | 0.134 | Blazar/BL Lac |  20.74${}^{+0.09}_{-0.14}$ |  2.04${}^{+0.05}_{-0.04}$ | 11.6 | 0.81 | 3
NGC 4102 | - | 12 06 23.11 |  $+$52 42 39.4 | 0.003 | LINER |  23.87${}^{+0.04}_{-0.03}$ |  1.74${}^{+0.12}_{-0.08}$ | 1.44 | 2.53 | 9
IGR J12418+78054,⋆ | LEDA 140000 | 12 42 36.10 |  $+$78 07 20.4 | 0.022 | Sy 1.9 | – | – | 1.00 | 0.94 | 8
PKS 1252+11 | - | 12 54 38.25 |  $+$11 41 05.9 | 0.872 | Blazar/QSO | 20.38 |  1.30${}^{+0.48}_{-0.48}$ | 1.77 | 0.58 | 1 (XRT)
IGR J13045-5630 | WISE J130431.77-563058.5 | 13 04 31.50 |  $-$56 30 54.8 | – | AGN |  23.29${}^{+0.24}_{-0.28}$ | 1.8 (fixed) | 1.82 | 0.91 | 13
RX J1317.0+3735 | - | 13 17 02.89 |  $+$37 35 32.7 | 0.195 | NLS1 | – | – |  | 1.02 | no (2-10) keV data
ESO 509-G038 | - | 13 31 13.84 |  $-$25 24 09.9 | 0.026 | Sy 1 | 20.44 |  1.56${}^{+0.09}_{-0.09}$ | 3.44 | 1.69 | 1 (XRT)
PKS 1413-36 | - | 14 16 33.16 |  $-$36 40 53.8 | 0.075 | AGN |  22.53${}^{+0.13}_{-0.11}$ | 1.8 (fixed) | 1.77 | 0.74 | 1 (XRT)
MRK 1383 | - | 14 29 06.57 |  $+$01 17 06.1 | 0.087 | Sy 1 | 20.41 |  1.87${}^{+0.02}_{-0.02}$ | 6.50 | 1.11 | 1 (XMM+NuSTAR)
MRK 817 | - | 14 36 22.08 |  $+$58 47 39.4 | 0.031 | Sy 1.2 |  22.84${}^{+0.05}_{-0.04}$ |  1.91${}^{+0.04}_{-0.09}$ | 6.67 | 1.74 | 14
MRK 477 | - | 14 40 38.09 |  $+$53 30 16.2 | 0.038 | Sy 2 |  23.30${}^{+0.06}_{-0.07}$ |  1.58${}^{+0.09}_{-0.07}$ | 3.38 | 1.27 | 9
IGR J14417-5533 | WISE J144118.74-553335.1 | 14 41 18.94 |  $-$55 33 33.5 | – | AGN | 21.57 |  1.55${}^{+0.24}_{-0.24}$ | 7.38 | 0.89 | 1 (XRT)
IGR J14557-5448 | LEDA 415943 | 14 55 32.19 |  $-$54 46 31.3 | – | AGN |  23.15${}^{+0.17}_{-0.12}$ | 1.8 (fixed) | 0.44 | 0.58 | 1 (XMM)
IGR J16005-4645 | PMN J1600-4649 | 16 00 20.40 |  $-$46 48 41.3 | – | AGN |  22.08${}^{+0.39}_{-0.51}$ | 1.8 (fixed) | 4.40 | 0.46 | 1 (XRT)
3C 332.0 | - | 16 17 42.54 |  $+$32 22 34.4 | 0.151 | Sy 1 |  22.01${}^{+0.17}_{-0.10}$ |  1.77${}^{+0.04}_{-0.04}$ | 9.22 | 1.12 | 1 (XRT + NuSTAR)
IGR J16181-5407 | 2MASS J16180771-5406122 | 16 18 07.74 |  $-$54 06 12.2 | 0.085 | AGN |  22.95${}^{+0.25}_{-0.65}$ |  0.8${}^{+1.10}_{-1.10}$ | 1.27 | 0.57 | 15
IGR J16246-4556 | 2MASS J16243080-4555144 | 16 24 30.77 |  $-$45 55 14.1 | – | AGN |  22.40${}^{+0.21}_{-0.45}$ |  1.3${}^{+0.70}_{-0.07}$ | 0.93 |  $<$0.59 | 15
IGR J16413-4046 | CXOU J164119.4–404737 | 16 41 19.5 |  $-$40 47 37.7 | – | AGN | 23 | 1.8 (fixed) | 1.40 | 1.45 | 16
IGR J16459-2325 | ESO 518-2 | 16 45 54.95 |  $-$23 27 05.5 | 0.020 | AGN |  $\sim$23.78 | 1.8 (fixed) | 4.30 | 1.58 | 1 (XRT)
IGR J16560-4958 | CXOU J165551.9–495732 | 16 55 51.95 |  $-$49 57 32.4 | – | AGN |  22.36${}^{+0.07}_{-0.11}$ |  2.3${}^{+0.70}_{-0.40}$ | 17.00 | 1.20 | 17
IGR J17157-5449 | 2MASS J17153752-5450062 | 17 15 37.53 |  $-$54 50 05.1 | – | AGN | 21.12 |  1.51${}^{+0.15}_{-0.15}$ | 4.25 | 0.59 | 1 (XRT)
IGR J17255-4509 | 2MASX J17253053-4510279 | 17 25 30.55 |  $-$45 10 27.3 | 0.019 | AGN |  21.25${}^{+0.24}_{-0.30}$ | 1.8 (fixed) | 2.91 | 0.54 | 1 (XRT)
SWIFT J1745.4+2906 | 1RXSJ174538.1+290823 | 17 45 38.29 |  $+$29 08 22.7 | 0.111 | Sy 1 |  $<$20.30 |  1.57${}^{+0.03}_{-0.03}$ | 7.08 | 1.25 | 1 (XRT+ NuSTAR)
IGR J18134-1636 | - | 18 13 28.03 |  $-$16 35 48.5 | – | AGN |  22.65${}^{+0.39}_{-0.33}$ | 1.8 (fixed) | 1.15 | 0.94 | 1 (XRT)
IGR J18141-1823 | 4PBC J1814.1-1822 | 18 14 14.78 |  $-$18 23 09.6 | – | AGN |  22.68${}^{+0.21}_{-0.19}$ | 1.8 (fixed) | 0.98 | 0.63 | 1 (XRT)
AX J1830.6-1002 | - | 18 30 38.3 |  $-$10 02 47.1 | – | AGN |  23.03${}^{+0.12}_{-0.13}$ |  1.01${}^{+0.57}_{-0.38}$ | 3.20 | 1.00 | 18
IGR J18381-0924 | CXOU J183818.5-092552 | 18 38 18.58 |  $-$09 25 52.2 | 0.031 | Sy 1.9 |  22.34${}^{+0.03}_{-0.03}$ |  1.19${}^{+0.07}_{-0.07}$ | 2.30 | 0.81 | 19
SWIFT J1839.1-5717 | allWISE J183905.95-571505.1 | 18 39 06.37 |  $-$57 15 05.8 | – | AGN |  22.31${}^{+0.07}_{-0.07}$ |  1.57${}^{+0.21}_{-0.21}$ | 8.40 | 1.27 | 11
IGR J18486-0047 | CXOU J184825.4?004635 | 18 48 25.45 |  $-$00 46 34.9 | – | AGN |  23.45${}^{+0.17}_{-0.28}$ | 1.8 (fixed) | 1.63 | 0.85 | 1 (XRT)
IGR J18497-0248 | NVSS J184946-024819 | 18 49 46.67 |  $-$02 48 17.3 | – | AGN |  $\sim$22.60 | 1.8 (fixed) | 1.08 | 0.70 | 1 (XRT)
IGR J19294+1328 | CXOU J192930.1+132705 | 19 29 30.11 |  $+$13 27 05.6 | – | AGN |  23.89${}^{+0.25}_{-0.21}$ | 1.8 (fixed) | 1.87 | 0.85 | 1(XRT), 14
SWIFT J1937.5-40212 | LEDA 588288 | 19 37 13.47 |  $-$40 16 14.8 | 0.075 | AGN |  22.23${}^{+0.09}_{-0.10}$ |  1.51${}^{+0.25}_{-0.25}$ | 3.92 | 0.31 | 1(XRT)
SWIFT J1937.5-40212 | 1RXS J193716.1-401026 | 19 37 14.70 |  $-$40 10 14.9 | – | AGN |  22.91${}^{+0.46}_{-0.67}$ |  1.92${}^{+0.21}_{-0.23}$ | 0.78 | 0.31 | 1(XRT)
IGR J19504+3319 | 2MASS J19501973+3314166 | 19 50 19.73 |  $+$33 14 16.2 | – | AGN |  22.04${}^{+0.14}_{-0.19}$ |  1.8${}^{+0.3}_{-0.3}$ | 2.24 | 1.34 | 20
IGR J19577+3339 | CXOU J195740.5+333828 | 19 57 40.59 |  $+$33 38 28.2 | – | AGN |  $<$23.5 |  -0.6${}^{+4.5}_{-1.6}$ | 0.26 | 0.53 | 20
IC 5063 | - | 20 52 02.33 |  $-$57 04 07.6 | 0.011 | Sy 2 |  23.36${}^{+0.02}_{-0.02}$ |  1.77${}^{+0.08}_{-0.07}$ | 8.70 | 4.92 | 9
SWIFT J2055.0+3559 | 2MASS J20550835+3556278 | 20 55 08.23 |  $+$35 56 27.4 |  0.115♣ | AGN |  23.02${}^{+0.16}_{-0.15}$ | 1.8 (fixed) | 2.50 | 0.47 | 1 (XRT)
IGR J20569+4940 | 4C 49.35 | 20 56 42.74 |  $+$49 40 06.6 |  0.100♣ | Blazar/BL Lac |  22.54${}^{+0.05}_{-0.05}$ |  2.60${}^{+0.03}_{-0.03}$ | 22.0 | 1.16 | 12
IGR J20596+4303(5) | - | 21 00 01.00 |  $+$43 02 11.0 | 0.066 | Sy 2 |  22.41${}^{+0.11}_{-0.13}$ | 1.8 | 1.49 | 0.57 | 21
IGR J22018+5049 | NRAO 676 | 22 01 43.54 |  $+$50 48 56.4 | 1.899 | Blazar/QSO | 21.57 |  1.39${}^{+0.07}_{-0.07}$ | 5.20 | 0.99 | 1 (XRT)
AX J2254.3+1146(2) | UGC 12237 | 22 54 19.67 |  $+$11 46 56.8 | 0.0286 | Sy 2 |  23.06${}^{+0.14}_{-0.13}$ | 1.8 (fixed) | 3.10 | 0.51 | 1 (XRT)
AX J2254.7+1146(2) | UGC 12243 | 22 54 43.51 |  $+$11 42 50.9 | 0.0278 | Sy 1 | 20.71 |  1.75${}^{+0.72}_{-0.79}$ | 0.13 | 0.51 | 1 (XRT)
1ES 2344+514 | - | 23 47 04.84 |  $+$51 42 17.9 | 0.044 | Blazar/BL Lac | 21.18 |  1.96${}^{+0.02}_{-0.02}$ | 17.0 | 0.58 | 1 (XRT)

##  Appendix B Swift/XRT fields of multiple counterparts

In this Appendix, the Swift/XRT fields of peculiar sources where multiple
counterparts have been found and discussed in Section 3, are shown. To
visualise better and highlight the X-ray counterparts of the new INTEGRAL AGN,
the images have been smoothed, therefore the presence of grains and/or
features inside the XRT field of view are undoubtedly spurious.

Figure 5: Left: Swift/XRT 0.3-10 keV image of IGR J04288-6702 also SWIFT
J0428.2-6704. The two X-ray counterparts are inside the 99% IBIS positional
uncertainty (dashed circle). Source #1 is the the Seyfert 1.5 LEDA 299570 at
z=0.065, while source #2 is SXPS J042749.2-670434, the eclipsing low-mass
X-ray binary also detected in the Fermi/LAT catalogue (error ellipse). Right:
0.3-10 keV band image of PKS 0441-0017 (source #1) and 1RXS J044229.8-001823
(source #2), both well inside the 90% IBIS error circle. The small dashed-
dotted ellipse corresponds to the Fermi/LAT positional error of 4FGL
J0442.6-0017.

Figure 6: Left: Swift/XRT 0.3-10 keV image of SWIFT J0835.5-0902. Two X-ray
counterparts are well inside the IBIS (continuous circle) and BAT (dotted
circle) error circles. Source #1 is the AGN candidate 2MASX J08353333-0905302,
while source #2 is associated with the variable star ASAS J083531-0904.1.
Right: 0.3-10 keV image of SWIFT J1937.5-4021. Source #1, which lies inside
the IBIS (continuous circle) and BAT (dotted circle) 90% positional
uncertainty, is the Seyfert 2 LEDA 5882882. Source #2, which is well inside
the BAT error circle, is instead located inside the 99% IBIS positional
uncertainty (dashed circle) and it is associated with 1RXS J193716.1-401026.
Figure 7: Swift/XRT 0.3-10 keV image of AX J2254.3+1146, also called SWIFT
J2254.2+1147. Two likely counterparts are detected in X-rays. Source #1, which
falls within the 90% IBIS positional uncertainty (filled circle) is the
Seyfert 2 UGC 12237, while source #2, which is detected within the 99% IBIS
error circle (dashed circle) is the Seyfert 1 UGC 12243.

##  Appendix C Radio images of resolved AGN candidates

The radio images of the resolved sources discussed in section 4.1 are shown in
figure 8 and 9. For three of them, only VLASS (IGR J19577+3339) or RACS (IGR
J08297-4250 and IGR J16005-4645) images are available, while for the radio
galaxy PKS 1413-36 both VLASS and RACS images could be retrieved. VLASS, with
a resolution of $\sim$2.5 arcsec and an average RMS of $\sim$0.120 mJy/beam,
is more sensitive to compact features ($<$1 arcmin), while RACS, at a
resolution of 25 arcsec and average RMS of $\sim$0.25 mJy/beam, is able to
recover extended emission up to $\sim$1 deg.

Figure 8: Left panel: VLASS image of source IGR J19577+3339, contours are
3$\times$RMS$\times$(1,2,4,8,16,32,64). Right panel: RACS image of source IGR
J08297-4250, contours are RMS$\times$(5,6,7,8,9,10). The angular resolution is
shown in the lower-left corner.

Figure 9: Left panel: VLASS image of source PKS 1413-36 with overlayed
contours from RACS, corresponding to
3$\times$RMS$\times$(1,2,4,8,16,32,64,128). Right panel: RACS image of source
IGR J160005-4645, contours are 3$\times$RMS$\times$(1,2,4,8,16,32,64,128,256).
The angular resolution is shown in the lower-left corner.