# The Shape of Dark Matter Haloes
IV. The Structure of Stellar Discs in Edge-on Galaxies

S. P. C. Peters1, G. de Geyter2, P. C. van der Kruit1 and K. C. Freeman3
1Kapteyn Astronomical Institute, University of Groningen, P.O.Box 800, 9700AV
Groningen, the Netherlands
2Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281-S9, 9000 Gent,
Belgium
3Research School of Astronomy and Astrophysics The Australian National
University, Cotter Road Weston Creek, ACT 2611,
Australia For more information, please contact P.C. van der Kruit at
<EMAIL_ADDRESS>
(Accepted 2015 month xx. Received 2015 Month xx; in original form 2015 Month
xx)

###### Abstract

We present optical and near-infrared archival observations of eight edge-on
galaxies. These observations are used to model the stellar content of each
galaxy using the FitSKIRT software package. Using FitSKIRT, we can self-
consistently model a galaxy in each band simultaneously while treating for
dust. This allows us to accurately measure both the scale length and scale
height of the stellar disc, plus the shape parameters of the bulge. By
combining this data with the previously reported integrated magnitudes of each
galaxy, we can infer their true luminosities. We have successfully modelled
seven out of the eight galaxies in our sample. We find that stellar discs can
be modelled correctly, but have not been able to model the stellar bulge
reliably. Our sample consists for the most part of slow rotating galaxies, and
we find that the average dust layer is much thicker than what is reported for
faster rotating galaxies.

###### keywords:

galaxies: haloes, galaxies: kinematics and dynamics, galaxies: photometry,
galaxies: spiral, galaxies: structure

††pagerange: The Shape of Dark Matter Haloes IV. The Structure of Stellar
Discs in Edge-on Galaxies–3††pubyear: 2015

##  1 Introduction

This is the fourth paper in a series of five where we try to constrain the
flattening of dark matter haloes from observations of the thickness and
velocity dispersion of the HI layer in edge-on late-type dwarf galaxies. For
this analysis we need to correct for the influence of the stellar disks on the
dynamics of the gas and therefore we provide in this paper fits to the light
distribution in the stellar disks of our sample galaxies.

Edge-on galaxies offer a unique perspective on the distribution of stars and
dust in galaxies. A major advantage of the edge-on view is the ability to
resolve the vertical distribution of both the stars and the dust, and this is
exactly the reason that in this series of papers we study edge-ons. A well-
known feature of edge-on spiral galaxies are truncations at the outer edge of
their stellar discs, as discovered in edge-on galaxies back in 1979 (van der
Kruit, 1979). Subsequent authors have confirmed the presence of truncations,
such as the study of 34 edge-on galaxies by Kregel et al. (2002a), who found
that at least 20 of these galaxies ($\sim\\!60\%$ of the sample) have
truncations. Not all galaxies are truncated. Some even appear to have an
upturn in their radial profiles (Erwin et al., 2008), although van der Kruit &
Freeman (2011) noted that many of these, e.g. NGC 3310, show signs of merging
or other distortions in the outer parts. Some galaxies extend out to many
scalelengths, such as NGC3́00 (Bland-Hawthorn et al., 2005). In this series op
papers we do not concern ourselves with the outer features, as we model the HI
only in the inner parts in order to set limits of the three-dimensional shape
of dark matter halos. In Paper V we determine out to which radius we feel our
data justify fitting for the shape of the dark matter halos; the actual radii
adopted for analysis vary from less than 1 out to typically 4 or 5
scalelengths, so we do not go out into these areas of extended stellar disks
or upturns. Also, if any of our systems would have a truncation, our analysis
is restricted to the areas within that truncation.

A major drawback to the edge-on perspective is the more complex geometry,
which implies that each position $x$ along the major axis is a superposition
of light emitted at a range of radii $R$. Various authors have therefore set
out to disentangle edge-on galaxies and extract their radial structure. One
approach to this is to deproject the edge-on image using the inverse Abel
transform (Binney & Tremaine, 1987). This method was first applied by Florido
et al. (2001, 2006) in a study of the mid-plane of edge-on galaxies in the
near infrared. Pohlen et al. (2007) extended the method to study both the
radial and vertical distribution of eleven edge-on galaxies. UGC 7321 was
studied in this way by O’Brien et al. (2010).

Dust can seriously hamper this type of deprojection, as there is no simple way
to incorporate its complex interplay of scattering, absorption and emission,
in the inverse Abel transform. An alternative strategy for deriving the radial
properties of the galaxy is to model the entire galaxy including the dust. By
using appropriate fitting algorithms, the model can be tweaked in various ways
until it matches the observations. Various authors applied this method to
edge-on galaxies, such as Xilouris et al. (1999) and Bianchi (2007).

FitSKIRT was developed by de Geyter et al. (2013) as an automatic fitting
extension for the SKIRT 3D-continuum Monte-Carlo radiative transfer code (Baes
& Dejonghe, 2001a, b; Baes et al., 2003, 2011). FitSKIRT makes use of the
GAlib genetic algorithm to fit a parameterised model of a galaxy (Wall, 1996).
In the so-called oligochromatic mode, the code can fit multiple bands
simultaneously. This mode was used by de Looze et al. (2012) to model edge-on
galaxy NGC 4565 from the UV to the mid-infrared in a self-consistent manner.
This method has been applied by de Geyter et al. (2014) to a set of twelve
edge-on galaxies selected from the CALIFA survey.

In the previous paper (number III in thsi series), we have modelled the HI
structure and kinematics of eight edge-on dwarf galaxies, as part of our
project to model their dark matter halo by inferring its properties from the
baryonic content. In the current paper, we continue this project by modelling
the stellar and dust components of these eight edge-on galaxies. We have
collected a large set of observations, which we present in Section 2. The
models and strategy by which we fit the data are presented in Section 3. The
fits to the data using FitSKIRT are presented in Section 4, after which we
discuss the results in Section 5 and conclude the paper in Section 6.

##  2 Data

FitSKIRT can model observations ranging from the UV to the infrared. The more
bands are available to it, the better the models can be constrained. In this
papers, we continue the analysis of the eight edge-on galaxies from the
previous papers in this series. See Table 2 in Paper I for an overview of the
sample. In order to get the largest dataset, a wide range of archives, both
online and off-line, has been explored. For most galaxies, a large set of
archived observations were found. Unfortunately, the signal-to-noise ratio in
many of these (survey) observations was insufficient, as the low surface
brightness nature of most of these galaxies necessitated longer exposure times
than were used. In total, we use data from ten telescopes in nine bands,
giving a minimum of three bands per galaxy, and a maximum of nine. A full
overview of the observations that we used is shown in Table 2 in the online
Appendix.

###  2.1 Data Reduction

FitSKIRT does not require the data to be calibrated, so we skipped that step
in the reduction. As our observations come from a wide range of telescopes,
each required its own, appropriate treatment.

2.3m ANU Advanced Technology Telescope

The 2.3m ANU Advanced Technology Telescope with the CASPIR near-IR camera,
located at Siding Spring observatory in Australia, was used to observe several
of the galaxies in the Kn- and H-bands. The data were archived on tape and was
originally intended for use in O’Brien et al. (2010). The CASPIR instrument
has dedicated software for reducing the data, which suffered from code-rot and
did not work correctly any more. With support from Peter McGrergor at the
Research School of Astronomy & Astrophysics in Canberra, Australia, along with
the manual and source code for CASPIR, we managed to reconstruct the required
workflow and re-implement this in Python.

During an observing run, various types of observations are being made: bias,
dark, flat, sky and object. First, we create the combined bias and this from
all other types of frames. CASPIR has a non-linear response and it was thus
required to linearise the flat, dark sky and object frames. The dark currents
were then removed from the sky, object and flat frames, after which the sky
and object frames were flat-fielded. The sky in the near infrared is bright
and varies rapidly. The main observations were therefore taken as one short
object frame followed by a sky frame. The sky frames before and after each
object frame were used to subtract the sky from a particular object frame. The
field-of-view of CASPIR only covers a fraction of a galaxy, so a dithering
pattern was used to cover the entire galaxy. The information on the exact
dithering pattern was unavailable and we thus resorted to manually calibrating
the coordinate system of each frame, using iraf. Each galaxy consisted of more
than 50 object frames. Afterwards we use the Montage tool-kit111Available at
montage.ipac.caltech.edu/. to automatically create a montage of all these
frames. This process automatically performs background rectification between
the various frames.

3.9m Anglo-Australian Telescope

The IRIS2 instrument on the 3.9m Anglo-Australian Telescope, located at Siding
Spring observatory in Australia, was used for various Ks- and H-band
observations. Observations were available on tape and were originally intended
for use in O’Brien et al. (2010). In contrast to the 2.3m ANU Advanced
Technology Telescope observations, the field-of-view is much larger and covers
the entire galaxy and the surrounding patch of sky. The IRIS2 instrument has
custom software, which automatically runs through the entire workflow and
returns the reduced science-ready frame.

ANU 40-inch Telescope

The Australian National University (ANU) 40-inch telescope, located at Siding
Spring Observatory in Australia, was used to observe several of our galaxies,
as intended for use in O’Brien et al. (2010). The data was archived on tapes.
The traditional IRAF workflow of bias and flat-fielding removal was performed
to reduce the data.

CTIO 0.9-meter Telescope

The R-band image for ESO115-G021 was taken using the 0.9-meter Telescope
located at the Cerro Tololo Inter-American Observatory (CTIO) in Chili. The
observation was taken as part of the Spitzer Local Volume Legacy project and
was provided science-ready online at the NASA/IPAC Extragalactic Database
(NED)222Available at ned.ipac.caltech.edu/..

Danish 1.54-meter Telescope

The Danish 1.54-m Telescope is located at the European Southern Observatory
(ESO) La Silla site in Chili. The R-band image for ESO 274-G001 was previously
published by Rossa & Dettmar (2003) and was available science-ready online via
NED.

ESO 1-meter Schmidt Telescope

The ESO-LV survey Lauberts & Valentijn (1988) digitised 606 blue and 606 red
ESO photographic survey plates. The data was available science-ready through
NED.

ESO La Silla Schmidt telescope

The ESO red-band survey has been digitised using the MAMA microdensitometer
and provided as science-ready data and available through a virtual-observatory
(VO) interface. These images were originally part of the ESO(B) Atlas, taken
with the ESO 1-m Schmidt telescope at La Silla, Chile (Lauberts, 1982).

Palomar 48-inch Schmidt Telescope

The 48-inch Schmidt telescope at Palomar Observatory in the United States was
used to create the Palomar Sky Survey (POSS). This survey was later digitised
into the Digitized Sky Survey (DSS). The data was provided science-ready
through a virtual-observatory interface.

Spitzer Space Telescope IRAC

The Spitzer Space Telescope archive had $3.6\,\mu$m observations of all our
galaxies and for several also $4.5\,\mu$m observations. The observations were
taken for a range of projects (Dale et al., 2009; Sorce et al., 2012;
Engelbracht et al., 2008; Sheth et al., 2010; Radburn-Smith et al., 2011;
MacLachlan et al., 2011). The Spitzer Heritage Archive333Available at
sha.ipac.caltech.edu/applications/Spitzer/SHA. provided direct online access
to the science-ready frames.

UK 48-inch Schmidt Telescope

The UK 48-inch Schmidt, located at Siding Spring in Australia, was used in an
all-sky survey. This was digitised into the DSS and was available science-
ready through a virtual-observatory interface.

###  2.2 Astrometric Calibration

The astrometric solution associated with the various observations would often
be in disagreement between bands, causing galaxies to be offset slightly
between bands. We therefore used the solve-field program, which is part of the
astrometry.net project, to fit a new astrometric calibration to all the
observations. The telescopes and cameras used in this study are of a large
variety and consequnetly not a single limiting magnitudes in the bands can be
given for our sample. In general, our photometry does not go as deep as the
Comerón et al. (2011) study of edge-on galaxies, but our interest is in the
brighter levels in order to constrain the light distribrutions for our
modelling.

###  2.3 Masking

To avoid flux contamination, it was required to mask all fore- and background
objects. For each galaxy, the band with the most prominent stars was selected.
We used the ds9 display tool to draw regions on each object, after which a
custom Python program set the pixels in these regions to a value of zero.
Pixels with a value of zero are ignored by FitSKIRT, and we thus do not need
to interpolate over them. We also used this program to draw a polygon around
each galaxy, beyond which the image was masked. In most cases there was only
little masking required. The galaxies closer to the galactic plane, however,
required far more extensive masking, with the total amount of masks drawn for
ESO 274-G001 well beyond a thousand. The region masks were copied to the other
bands using ds9. The files were then inspected and additional masking applied
where required.

###  2.4 Normalization

To avoid overly long computations, all images were rotated to align their
major axis with the horizontal image axis, and then shrunk down to a width of
$\sim 700$ pixels. We subtract the average background from the image. The
image was then divided by the total flux, such that the sum of the image
became one. This last step is required by FitSKIRT, as it prevents a
particularly bright band from dominating the fitting result.

Figure 1: Stellar decompositions for IC 2531. Each band consists of three
panels. Top panels show the observation. Middle panels show the best-fit
models. The lower panels show the difference maps. Colour scaling is equal
between the three panels. The scale of the images is in arcsec.

Figure 2: Stellar decompositions for the left side of IC 5052 (1/2). Each band
consists of three panels. Top panels show the observation. Middle panels show
the best-fit models. The lower panels show the difference maps. Colour scaling
is equal between the three panels. The scale of the images is in arcsec.

Figure 3: Stellar decompositions for the left side of IC 5052 (2/2). Each band
consists of three panels. Top panels show the observation. Middle panels show
the best-fit models. The lower panels show the difference maps. Colour scaling
is equal between the three panels. The scale of the images is in arcsec.

Figure 4: Stellar decompositions for the right side of IC 5052 (1/2). Each
band consists of three panels. Top panels show the observation. Middle panels
show the best-fit models. The lower panels show the difference maps. Colour
scaling is equal between the three panels. The scale of the images is in
arcsec.

Figure 5: Stellar decompositions for the right side of IC 5052 (2/2). Each
band consists of three panels. Top panels always show the observation. Middle
panels show the best-fit models. The lower panels show the difference maps.
Colour scaling is equal between the three panels. The scale of the images is
in arcsec.

Figure 6: Stellar decompositions for IC 5249 (1/2). Each band consists of
three panels. Top panels always show the observation. Middle panels show the
best-fit models. The lower panels show the difference maps. Colour scaling is
equal between the three panels. The scale of the images is in arcsec.

Figure 7: Stellar decompositions for IC 5249 (2/2). Each band consists of
three panels. Top panels always show the observation. Middle panels show the
best-fit models. The lower panels show the difference maps. Colour scaling is
equal between the three panels. The scale of the images is in arcsec.

Figure 8: Stellar decompositions for ESO 115-G021. Each band consists of three
panels. Top panels always show the observation. Middle panels show the best-
fit models. The lower panels show the difference maps. Colour scaling is equal
between the three panels. The scale of the images is in arcsec.

Figure 9: Stellar decompositions for ESO 138-G014. Each band consists of three
panels. Top panels always show the observation. Middle panels show the best-
fit models. The lower panels show the difference maps. Colour scaling is equal
between the three panels. The scale of the images is in arcsec.

Figure 10: Stellar decompositions for ESO 146-G014. Each band consists of
three panels. Top panels always show the observation. Middle panels show the
best-fit models. The lower panels show the difference maps. Colour scaling is
equal between the three panels. The scale of the images is in arcsec.

Figure 11: Stellar decompositions for ESO 274-G001. Each band consists of
three panels. Top panels always show the observation. Middle panels show the
best-fit models. The lower panels show the difference maps. Colour scaling is
equal between the three panels. The scale of the images is in arcsec.

Figure 12: Stellar decompositions for UGC 7321. Each band consists of three
panels. Top panels always show the observation. Middle panels show the best-
fit models. The lower panels show the difference maps. Colour scaling is equal
between the three panels. The scale of the images is in arcsec.

##  3 Data Fitting

The data will be modelled using FitSKIRT with the following components (de
Geyter et al., 2013). The disc of each galaxy is modelled as a double-
exponential disc. No truncation was included in the model, as this is
currently not supported by FitSKIRT. Truncations are known to occur near the
onset of the HI warp (van der Kruit, 2007) and this region is not of
interested for our goal of measuring the mid-plane hydrostatics (see also
Section 2 of Paper III). Developing a truncated model was discussed, but
considering the quality of the data, the current research questions and the
computational cost associated with additional free parameters, we have decided
not to develop such an option. The disc thus follows the luminosity
distribution

$j(R,z)=\frac{L_{\textrm{d},*}}{4\pi
h^{2}_{R,*}h_{z,*}}\exp{\left(-\frac{R}{h_{R,*}}\right)}\exp{\left(-\frac{|z|}{h_{z,*}}\right)}\,\,,$
(1)

with $L_{\textrm{d},*}$ the total disc luminosity, $h_{R,*}$ and $h_{z,*}$ the
disc scale length and scale height, and $R$ and $z$ as the radial and vertical
coordinates.

The assumption of a double-exponential model in our fits is a simplification
of reality. It is well-known that better fits are possible; van der Kruit
(1988) proposed a sech-function as a compromise between the isothermal sech2
distribution of van der Kruit & Searle (1981), which ignores the real
situation that there are most likely age groups of stars with different
velocity dispersions, and the mathematically convenient, but unphysical
exponential. We believe our fits are sufficiently satisfactory that any
further sophistication is not necessary, also in view of the fact that at low
$z$, where the exponential and the sech deviate most, dust extinction would
need to be fitted more realistically then the crude way we apply here, namely
also with a double exponential. Also the scaleheight of the stars may very
well change with galactocentric distance, as found by de Grijs & Peletier
(1997) and Narayan & Jog (2002). Again our fits work very well with a constant
scaleheight, and we therefore believe these are adequate for our purposes. We
return to this issue in section 5.2.

Our galaxies are close to edge-on and already van der Kruit & Searle (1981)
showed that small variation in invclination away from perfectly edge-on do not
affect the determined scale height. Nevertheless, we leave the inclination in
as a parameter (see below).

A bulge was also included, which follows the luminosity density (de Geyter et
al., 2013)

$\displaystyle j(R,z)$ $\displaystyle=$
$\displaystyle\frac{L_{\textrm{b},*}}{qR_{\textrm{e}}^{3}}S_{\textrm{n}}\left(\frac{m}{R_{\textrm{e}}}\right)\,\,,$
(2) $\displaystyle m$ $\displaystyle=$
$\displaystyle\sqrt{R^{2}+\frac{z^{2}}{q^{2}}}\,\,,$ (3)

with the total bulge luminosity $L_{\textrm{b},*}$, the effective radius
$R_{e}$, the Sérsic function

$S_{\textrm{n}}=I_{e}\exp-C\left[\left({R\over R_{e}}\right)^{1/n}-1\right]$

(with the proper normalization) and the flattening of the bulge $q$. In
general our photometry is not deep enough to look for thick disks and what we
fit as bulges may very well be the brighter parts of suchgcomponents.

The dust is also modelled as a double-exponential disc

$\rho_{\textrm{d}}(R,z)=\frac{M_{\textrm{d}}}{2\pi
h^{2}_{R,d}h_{z,d}}\exp{\left(-\frac{R}{h_{R,d}}\right)}\exp{\left(-\frac{|z|}{h_{z,d}}\right)}\,\,,$
(4)

with the dust density $\rho$, the total dust mass $M_{\textrm{d}}$, and the
dust scale length and scale height $h_{\textrm{R,d}}$ and $h_{\textrm{z,d}}$.
The galaxies in our sample are late-type dwarfs and we do not expect them to
have a lot of dust. We include dust in the results for completeness, but
stress that we are skeptical about the exact quantities returned by the
fitting. The inclination can vary between $86^{\circ}$ and $90^{\circ}$ to get
the best fit. However, with the absence of dust bands in most of our galaxies,
we cannot confirm the exact inclination.

Including the inclination $i$ and the exact central position, the model has a
total of 11 global free parameters, plus two additional free parameters per
band (the disc luminosity $L_{\textrm{d},*}$ and bulge-to-disc ratio $B/D$).
FitSKIRT fits the data using the GaLib genetic algorithm (Wall, 1996). We use
a population of 200 individuals and evolve the model for 100 iterations. We
run five fits for each galaxy. The Millipede Cluster of the University of
Groningen was used to perform all fits. A fit typically takes 30 hours.

Due to the random path that the light follows in the model, no two instances
of the model will be the same. As such, both the observation and the model
contain Poisson distributed noise. The objective function to measure the error
is therefore

$\displaystyle\chi^{2}$ $\displaystyle=$
$\displaystyle\sum_{j}^{N_{\textrm{pix}}}{\frac{\left(I_{\textrm{mod},j}-I_{\textrm{obj},j}\right)^{2}}{\sigma^{2}}}\,\,,$
(5) $\displaystyle=$
$\displaystyle\sum_{j}^{N_{\textrm{pix}}}{\frac{\left(I_{\textrm{mod},j}-I_{\textrm{obj},j}\right)^{2}}{|I_{\textrm{obj},j}|+I_{\textrm{mod},j}}}\,\,.$
(6)

The lowest $\chi^{2}$ value is adopted as the true value. The error in each
parameter is taken as the standard deviation from the five runs.

##  4 Results

The results for each galaxy are shown in Table 1. The quality of the
individual fits can be seen in Table 3 in the online Appendix. When available,
we also list the published integrated magnitude $L_{\textrm{band,*}}$. Where
needed, these have been corrected for Galactic foreground extinction using the
Schlafly & Finkbeiner (2011) re-calibration of the Schlegel et al. (1998)
infrared-based dust map, as calculated in NED. Before the disc luminosity
$L_{\textrm{d},*}$ produced in FitSKIRT can be used for further analysis, it
first needs to be calibrated. This can be done by multiplying it with
$10^{15}L_{\textrm{band,*}}$, where $L_{\textrm{band,*}}$ is the integrated
luminosity, expressed in W/m2, as measured without dust absorption.

###  4.1 IC 2531

Galaxy IC 2531 is the only Sb galaxy in our sample, and has the highest
maximum circular velocity at $v_{\textrm{max}}=260.5$ km/s (Table 1). This is
nearly twice the maximum circular velocity of the other galaxies in our
sample. The central brightness component has not been reproduced correctly.
This bulge is most likely peanut-shaped or boxy, which requires a different
bulge model than adopted here (Jarvis, 1986; de Souza & Dos Anjos, 1987). The
scale length is $h_{\textrm{R},*}=5077\pm 262$ pc and the scale height
$h_{\textrm{z},*}=613\pm 46$ pc. Kregel et al. (2002a) report a much longer
$h_{\textrm{R},*}=12511\pm 2643$ pc and $h_{\textrm{z},*}=658.5\pm 65.8$ pc.
The galaxy features a very prominent dust lane, which Kregels I-band model
does not treat for and so their scale length might be overestimated. Xilouris
et al. (1999) has also performed a fit to the galaxy that did include a
treatment for the dust. They report a K-band scale length of
$h_{\textrm{R},*}=5.04\pm 0.1$ kpc and a scale height of $0.45\pm 0.02$ kpc.
The dust is found to have a (K-band) scale length of $h_{\textrm{R},d}=8.00\pm
0.3$ kpc and a scale height of $h_{\textrm{z},d}=0.22\pm 0.03$ kpc, which is
similar to the $h_{\textrm{R},d}=7.0\pm 2.2$ kpc and $h_{\textrm{z},d}=0.3\pm
0.1$ kpc reported here.

###  4.2 IC 5052

Galaxy IC 5052 has proven hard to model, as the galaxy showed clear
asymmetries. We therefore opted to model both sides of the galaxy separately
(Figures 2, 3, 4 and 5). This forced us to fix the centre of the galaxy, which
has clearly hampered the results. From an inspection of the images, we
conclude that the left side better represents the galaxy, although the fit is
far from perfect. The scale length for the left side $h_{\textrm{R},*}$ is
$857\pm 68$ pc and the scale height $h_{\textrm{z},*}$ is $124\pm 80$ pc,
which makes this the galaxy with the shortest scale length in our sample.
Comerón et al. (2011) has also modelled this galaxy using a double disc
approach, and report a thick disc scale length of 470-530 pc and a thin disc
scale length of 140-170 pc. They note that the galaxy can also be modelled
successfully with a single disc. Overall, we find that the galaxy is very
clumpy in its light distribution, which cannot be fit properly by the models.
Our fitted scalelength differs considerably between the two sides, and both
are much larger than the determined value of Comerón et al. (2011). Our result
should be treated with much cuation. This galaxy proven to be too difficult to
model for our purposes and it has been deleted from our sample in Paper V,
where we do the final analysis.

###  4.3 IC 5249

The overall quality of the fit is very good. The scale length is
$h_{\textrm{R},*}=6828\pm 340$ pc, while the scale height is
$h_{\textrm{z},*}=242\pm 20$ pc. Similar results have also been found in
previous studies. Carignan (1983) analysed the galaxy in the B-band and
distinguished two components wityh scale lengths 18 kpc and 2.5 kpc. Wainscoat
(1986) confirmed these results using H, I and K-band data. The galaxy was also
analysed by Byun (1992) in the B, R and I (van der Kruit et al., 2001). Abe et
al. (1999) discovered a very sharp truncation at two scale lengths. We do not
find any indication of a second disc component as Carignan (1983), although
their second component might well have been the bulge we find here. This
galaxy is an example of a so-called superthin galaxy. van der Kruit et al.
(2001), who found a scale lenght of about 7 kpc attributed this to the
relatively long scale length combined with the low (face-on) surface
brightness.

###  4.4 ESO 115-G021

A large amount of masking was required for ESO 115-G021 (Figure 8). The dwarf
galaxy has been modelled successfully, although it is still clumpy. The
stellar disc scale length $h_{\textrm{R},*}$ is only $1108\pm 280$ pc, while
the scale height $h_{\textrm{z},*}$ is only $149$ parsec. The galaxy is very
faint and emits only $5.0\times 10^{7}$L⊙ in the R-band. In comparison to the
neutral hydrogen mass, the $M_{\textrm{HI}}/L_{\textrm{R}}$ is 12.5, the
highest in our sample.

###  4.5 ESO 138-G014

ESO 138-G014 also required extensive masking (Figure 9). Despite this, the
overall fit is good. With $h_{\textrm{R},*}=2288\pm 59$ pc and
$h_{\textrm{z},*}=217\pm 10$ pc, the stellar disc is twice as long as ESO
115-G021 and slightly thicker. Kregel et al. (2002a) previously modelled this
galaxy without dust and reported a larger disc with $h_{\textrm{R},*}=3779$ pc
and $h_{\textrm{z},*}=382\pm 10$ pc.

###  4.6 ESO 146-G014

ESO 146-G014 is a known low-surface brightness galaxy and is extremely metal
poor (Roennback & Bergvall, 1995; Morales-Luis et al., 2011). The galaxy is a
slow rotator $v_{\textrm{max}}=84.1$ km/s and is very patchy in nature, as can
be seen in Figure 10. Because of this, the fit is far from perfect. As can be
seen in all three bands, the galaxy has a very bright central region, but also
has a bright spot 50” east of the centre. The galaxy is also asymmetric, as
can be seen most clearly in the V-band image.

###  4.7 ESO 274-G001

Galaxy ESO 274-G001 is very close to the Galactic plane, with a Galactic
latitude of only $9.3^{\circ}$. The four bands therefore required an
exceptional amount of masking (Figure 11), but the fit was still successful.
The galaxy has a stellar disc scale length $h_{\textrm{R},*}$ of $1270\pm 59$
pc and a scale height $h_{\textrm{z},*}$ of $161\pm 2$ pc, which is very
similar to ESO 115-G021. The overall appearance is different from that galaxy,
as ESO 274-G001 has a far more flattened bulge. Similar to the ESO 115-G021
and ESO 146-G014, the galaxy is a slow rotator, with a maximum circular
velocity of $v_{\textrm{max}}=103.9$ km/s. Moreover, similar to those two
galaxies, ESO 274-G001 is patchy in nature. The galaxy has the highest
luminosity compared to its optically thin HI mass:
$M_{\textrm{HI}}/L_{\textrm{R}}=0.8$

###  4.8 UGC 7321

UGC 7321 has been modelled using five bands (Figure 12), the results of which
have the lowest combined $\chi^{2}$ error in this sample. The scale length has
been measured at $h_{\textrm{R},*}=2498\pm 349$ pc and the scale height at
$h_{\textrm{z},*}=187\pm 80$ pc. This is in agreement with O’Brien et al.
(2010), who applied the deprojection method and reported
$h_{\textrm{d},*}=2650$ pc and $h_{\textrm{z},*}=245$ pc. The scale-height was
reported as 140-150 pc by Matthews et al. (1999), who did not discern a bulge.
We emphasize that our fitted bulge may also correspond to the brighter parts
of a thick disk,

O’Brien et al. (2010) performed a rotation-curve decomposition on the galaxy
and found a mass to light $M_{*}/L_{r^{\prime}}$ upper limit of 1.05. This
implies a recent burst of star formation in the galaxy, which matches the
detection of a significant fraction of young stars in the disc (Matthews et
al., 1999). O’Brien et al. (2010) also performed a fit to the vertical
hydrostatics of the disc and found a good fit at $M_{*}/L_{R}$ of 0.2.

##  5 Discussion

###  5.1 Quality of the Fits

What can we conclude about the overall quality of the fits? Comparing to the
available literature, we see that IC 2531, IC 5249 and UGC 7321 are in
agreement with the results by others. The slower rotating galaxies, e.g. ESO
115-G021, ESO 146-G014 and ESO 274-G001 all have a clumpy nature, which makes
fitting harder. For IC 5052 and ESO 138-G014, the parameters reported by other
authors are different. As we noted before, IC 5052 gave us problems to model,
so our results could well be wrong. ESO 138-G014 also required extensive
masking. It is a low surface brightness galaxy, but the fit we have performed
still looks acceptable (see Figure 9). As such, we feel that the derived
stellar disc scale lengths and scale heights are reasonably accurate, with the
possible exception of IC 5052.

A similar endeavor as the work done in this paper has been previously
undertaken by de Geyter et al. (2014), who set out to model edge-on galaxies
in the Calar Alto Legacy Integral Field Area Survey (CALIFA), which showed a
clear dust band. In total they settled on a sample of 12 –mostly early-type–
galaxies for which they performed an oligochromatic fit to the $g^{\prime}$,
$r^{\prime}$, $i^{\prime}$ and $z^{\prime}$ bands. While their data is of
higher quality, their results are very similar to ours, and they “conclude
that in general most galaxies are modelled accurately, especially when keeping
in mind that the FitSKIRT models only consist of three basic components and
they were determined by an automated procedure over a large parameters space
without strong initial boundary conditions” (de Geyter et al., 2014).

| Stellar | Stellar | Dust | Dust | Dust | Bulge | Bulge |  | Sérsic |
---|---|---|---|---|---|---|---|---|---|---
Name | scale length | scale height | scale length | scale height | mass | Radius | flattening | Inclination | Index | QOF
| [pc] | [pc] | [pc] | [pc] | [$10^{7}$ M⊙] | [pc] |  | ∘ |  |
IC 2531 | $5077\pm 262$ | $613\pm 46$ | $6997\pm 2213$ | $311\pm 109$ | $4\pm 1.3$ | $5451\pm 1775$ | $0.78\pm 0.22$ | $88.7\pm 0.8$ | $5.6\pm 1.0$ | G
IC 5052 (left) | $857\pm 68$ | $124\pm 80$ | $1500\pm 3655$ | $600\pm 15$ | $0.5\pm 0.44$ | $1600\pm 518$ | $0.25\pm 0.02$ | $86.0\pm 1.7$ | $0.5\pm 0.2$ | M
IC 5052 (right) | $1617\pm 129$ | $781\pm 299$ | $6664\pm 2042$ | $523\pm 96$ | $0.01\pm 0.5$ | $2149\pm 45$ | $0.16\pm 0.05$ | $87.7\pm 1.0$ | $0.5\pm 0.0$ | B
IC 5249 | $6828\pm 340$ | $242\pm 20$ | $4380\pm 677$ | $372\pm 67$ | $0.88\pm 0.2$ | $4602\pm 183$ | $0.22\pm 0.01$ | $88.8\pm 0.9$ | $2.9\pm 0.2$ | G
ESO 115-G021 | $1108\pm 280$ | $149\pm 101$ | $10515\pm 2057$ | $432\pm 69$ | $2.4\pm 0.47$ | $3810\pm 1159$ | $0.35\pm 0.06$ | $86.0\pm 0.7$ | $2.6\pm 0.7$ | G
ESO 138-G014 | $2288\pm 59$ | $217\pm 10$ | $3074\pm 508$ | $509\pm 34$ | $1.5\pm 0.23$ | $5843\pm 611$ | $0.18\pm 0.01$ | $86.8\pm 0.3$ | $3.7\pm 0.3$ | G
ESO 146-G014 | $5356\pm 1384$ | $1000\pm 422$ | $7115\pm 1063$ | $525\pm 58$ | $2.3\pm 0.47$ | $3264\pm 1356$ | $0.09\pm 0.10$ | $86.0\pm 0.0$ | $0.9\pm 0.3$ | G
ESO 274-G001 | $1270\pm 59$ | $161\pm 2$ | $11374\pm 373$ | $472\pm 33$ | $2.9\pm 0.69$ | $4880\pm 551$ | $0.06\pm 0.02$ | $86.8\pm 0.2$ | $0.6\pm 0.1$ | G
UGC 7321 | $2498\pm 349$ | $187\pm 80$ | $8568\pm 1956$ | $600\pm 139$ | $6.2\pm 1.1$ | $2532\pm 1013$ | $0.10\pm 0.02$ | $90.0\pm 1.1$ | $1.9\pm 0.7$ | G

Table 1: The global properties of the stellar fits per galaxy. QOF is the
quality of the fit: Good, Moderate or Bad.

###  5.2 On the $z$-distribution

A key assumption in our model is the use of a double-exponential disk (see
Equation 1). This choice was made as a basis for the hydrostatic equilibrium
calculations in Paper V. Other functional forms for the vertical distribution
were available, but were rejected as the quality of the observations does not
allow us to distinguish accurately enough between the various forms.

To demonstrate this, we have present the vertical distribution of UGC 7321
along a slice of the galaxy in Figure 13. UGC 7321 was one of our most
succesful fits, and as such the profiles between the model and the observation
match sufficiently well. But even in this slice, there is difference in the
quality of the fit. The Wise2 fit has been very well reproduced. Yet the
R-band profile has been reproduced considerably less well, showing excess
light futher above and beyond the plane. The fits are influenced by the fact
that the program tries to compensate for the local structures and
contaminations (e.g. stray light due to field stars). More accurate and less
contaminated observations are required to accurately test which functional
form of the vertical distribution works best.

Figure 13: Profile of a vertical slice of UGC 7321. The profile was taken at a
distance of 28.4′′ from the center of the galaxy. Solid lines represent the
observation. Dashed lines the simulated galaxy. Zeropoint is uncalibrated.

###  5.3 Discs and Bulges

Let us now compare the global properties of the stellar discs. Focusing on the
seven good fits, the average stellar disc scale length in our sample is
$h_{R,*}=3.49\pm 2.24$ kpc, while the average scale height of the stellar disc
is $h_{z,*}=0.37\pm 0.32$ kpc. As a comparison de Geyter et al. (2014) report
$4.23\pm 1.23$ kpc and $0.51\pm 0.27$ kpc for their 12 edge-on sample. They
also calculate the mean values for the 34 edge-on galaxies in Kregel et al.
(2002b), reporting $4.73\pm 2.57$ kpc and scale height of $0.57\pm 0.25$ kpc.
That sample consists of Sa, Sb and Sc type galaxies, while ours consists of
mostly of Sd type galaxies (Table 2 of Paper I of this series). IC 5249
appears to be a unique galaxy in terms of scale length to scale height ratio.
If we remove it from the sample, the averages becomes even more distinct with
$h_{R,*}=2.93\pm 1.85$ kpc and $h_{z,*}=0.38\pm 0.28$ kpc. It is typically not
expected that the scale lengths for disc galaxies depend on Hubble
morphological types between Sa and Sc (de Jong, 1996; Graham & de Blok, 2001).
However, for Scd and Sd galaxies, it was demonstrated using face-on galaxies
that the scale length tends to be significantly shorter (Fathi et al., 2010)
and our results are within expectations, although the range we find is large,
the mean is still less than the values we just quoted for Sa to Sc galaxies.

If we now focus on the scale length over scale height ratio, we find an
average of $h_{R,*}/h_{z,*}=11.6\pm 7.76$. IC 5249 has the by far highest
value at 28.2, which makes it a ‘super thin’ disc. Removing this one galaxy,
the average ratio becomes $h_{R,*}/h_{z,*}=8.81\pm 2.78$. A very similar value
of $h_{R,*}/h_{z,*}=8.26\pm 3.44$ was reported by de Geyter et al. (2014) for
their own sample, and a value of $h_{R,*}/h_{z,*}=8.21\pm 2.36$ for the Kregel
et al. (2002b) sample. We conclude that our measurements are, with the
possible exception of IC 5249, in good agreement with their samples.

Looking at the bulges, we find a typical bulge effective radius of
$R_{e}=4.34\pm 1.19$ kpc. This is longer than reported by de Geyter et al.
(2014), who reports the value of $R_{e}=2.31\pm 1.59$ kpc. This was already
large compared to the 1000 galaxies sample of Gadotti (2009), who reported
$R_{e}=0.84\pm 0.36$ kpc. It was argued by de Geyter et al. (2014) that this
difference is due to the lack of dust attenuation correction in Gadotti
(2009), and due to the lack of a treatment of bars in their own work. The
Gadotti (2009) sample does not contain many Sd galaxies; there might be
different averages that apply for an Sd sample. However, given our results
from the previous section, we argue that it is more likely that our bulges are
not fitted very reliably. The average Sérsic index we find is $2.6\pm 1.7$,
which is consistent with the $2.37\pm 1.35$ reported by de Geyter et al.
(2014). As we poinbted out above, there is a real possibility that our bulge
components really are the brighter parts of a thick disk.

###  5.4 Dust

Most of the galaxies in our sample are slow rotators. The Sd type galaxies
have a maximum circular rotation of $v_{\textrm{max}}=131.9$ km/s. Only IC
2531 has a much higher rotation of $v_{\textrm{max}}=260.5$ km/s (Table 4 of
Paper I). Dalcanton et al. (2004) found that for galaxies rotating slower than
a circular velocity of $v_{\textrm{max}}\\!\sim\\!120$ km/s, no dust lane
forms. Instead, the dust settles in more clumpy structure. Inspecting the
images of the galaxies, we can confirm this distinction as well in our own
sample, although it is hard to distinguish for the discs just above 120 km/s.
The average dust scale length and scale height are $h_{R,d}=4.34\pm 1.19$ kpc
and $h_{z,d}=0.46\pm 0.01$ kpc, while the ratio between the two is on average
$h_{R,d}/h_{z,d}=10.1\pm 4.4$. A typical dust scale length and height of
$h_{R,d}=6.03\pm 2.92$ and $h_{z,d}=0.23\pm 0.10$ was reported by de Geyter et
al. (2014). For the scale height similar values of $h_{z,d}=0.23\pm 0.08$ kpc
and $h_{z,d}=0.25\pm 0.11$ were reported by Xilouris et al. (1999) and Bianchi
(2007). Our galaxies thus typically have a thicker dust layer than the samples
of these authors.

Dalcanton et al. (2004) argued that for discs rotating slower than a circular
velocity of $v_{\textrm{max}}\\!\sim\\!120$ km/s the dust would follow a
thicker distribution than the faster rotating sample. Indeed, most of our
galaxies are below or near a circular velocity of 120 km/s. Taking the three
galaxies with circular velocities above 130 km/s, we have an average scale
length to scale height ratio of $h_{R,d}/h_{z,d}=13.8\pm 3.3$, compared to
$h_{R,d}/h_{z,d}=7.4\pm 2.7$ for the other four. The sample of de Geyter et
al. (2014) has a mean ratio of $h_{R,d}/h_{z,d}=26.2$, which is much closer to
our fast rotating galaxy at $h_{R,d}/h_{z,d}=17.5$.

However, UGC 7321 with a maximum circular velocity of $v_{\textrm{max}}=128$
km/s has a very different ratio of $h_{R,d}/h_{z,d}=4.2$. This galaxy also has
the most dust mass of the sample, with $6.2\times 10^{7}$ M⊙, compared to the
average of $2.8\pm 1.82\times 10^{7}$ M⊙ for the entire sample. There is no
distinction in terms of dust mass to be made between the slow and quick
rotators.

The dust scale length to stellar scale length ratio is on average
$h_{R,d}/h_{R,*}=1.88\pm 1.37$ in our sample. This is compatible to the
$h_{R,d}/h_{R,*}=1.73\pm 0.83$ reported by de Geyter et al. (2014). Xilouris
et al. (1999) reports $h_{R,d}/h_{R,*}=1.36\pm 0.17$ and Bianchi (2007) finds
$h_{R,d}/h_{R,*}=1.53\pm 0.55$, both values are compatible with ours. The dust
scale height to stellar scale height ratio we report is
$h_{z,d}/h_{z,*}=1.99\pm 1.15$. Although compatible, this is much higher than
the value of $h_{z,d}/h_{z,*}=0.55\pm 0.22$ reported by de Geyter et al.
(2014), the $h_{z,d}/h_{z,*}=0.58\pm 0.13$ reported by Xilouris et al. (1999)
and the $h_{z,d}/h_{z,*}=0.52\pm 0.49$ reported by Bianchi (2007). We thus
find that the dust to stellar scale length ratio of our late-type galaxies
sample is compatible to more early-type samples; the dust to stellar scale
height ratio is far higher. The dust in our slow rotating galaxies sample
forms into a much thicker disc, as predicted by Dalcanton et al. (2004).

##  6 Conclusions

In this paper, we have attempted to fit the bulge and disc of eight edge-on
dwarf galaxies using FitSKIRT automatically. The quality of our fit varies,
mostly due to limited quality of the available data and the intrinsic low
luminosity of these galaxies. Despite this, we have successfully recovered the
stellar discs in seven out of eight of the galaxies in our sample. The results
for the bulges are less reliable, which is most likely due to a lack of an
accurate description for bars in the code. We have also successfully measured
the dust distribution in these seven galaxies. The average dust scale length
to stellar scale length is compatible with other samples, but our dust scale
height to stellar scale height ratio is far higher than in typical other
samples. The HI mass to light ratio $M_{\textrm{{HI}}}/L_{R}$ varies
drastically between the various galaxies. It is only 0.2 in ESO 274-G001, yet
12.5 in ESO 115-G021.

## Acknowledgments

SPCP is grateful to the Space Telescope Science Institute, Baltimore, USA, the
Research School for Astronomy and Astrophysics, Australian National
University, Canberra, Australia, and the Instituto de Astrofisica de Canarias,
La Laguna, Tenerife, Spain, for hospitality and support during short and
extended working visits in the course of his PhD thesis research. He thanks
Roelof de Jong and Ron Allen for help and support during an earlier period as
visiting student at Johns Hopkins University and the Physics and Astronomy
Department, Krieger School of Arts and Sciences for this appointment.

PCK thanks the directors of these same institutions and his local hosts Ron
Allen, Ken Freeman and Johan Knapen for hospitality and support during many
work visits over the years, of which most were directly or indirectly related
to the research presented in this series op papers.

Work visits by SPCP and PCK have been supported by an annual grant from the
Faculty of Mathematics and Natural Sciences of the University of Groningen to
PCK accompanying of his distinguished Jacobus C. Kapteyn professorhip and by
the Leids Kerkhoven-Bosscha Fonds. PCK’s work visits were also supported by an
annual grant from the Area of Exact Sciences of the Netherlands Organisation
for Scientific Research (NWO) in compensation for his membership of its Board.

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##  Appendix A Tabular material

The following pages show the details of the observations in Table 2 and the
$\chi^{2}$ quality of the fit for each filter band in Table 3.

Galaxy | Filter | Telescope | Observer/Project | Date
---|---|---|---|---
IC 2531 | I | ANU 40inch Telescope | J.C. O’Brien | 02-03-2002
| R | ESO La Silla | ESO(B) Atlas | 04-02-1986
|  $3.6\mu$m | Spitzer IRAC | B. Tully | 06-03-2013
IC 5052 | B | ESO 1m Schmidt | ESO-LV project |
| H | 3.9m Anglo-Australian Telescope | S. Ryder & C. Tinney | 27-07-2002
| I | ANU 40inch Telescope | J.C. O’Brien | 10-07-2002
| J | UK 48-inch Schmidt | Digitized Sky Survey | 14-09-1976
| R | ESO 1m Schmidt | ESO-LV project |
| V | ANU 40inch Telescope | J.C. O’Brien | 12-07-2002
|  $3.6\mu$m | Spitzer IRAC | R. de Jong | 18-09-2005
|  $4.5\mu$m | Spitzer IRAC | R. de Jong | 18-09-2005
IC 5249 | B | ESO 1m Schmidt | ESO-LV project |
| H | 3.9m Anglo-Australian Telescope | S. Ryder & C. Tinney | 28-07-2002
| I | ANU 40inch Telescope | J.C. O’Brien | 15-07-2002
| J | UK 48-inch Schmidt | Digitized Sky Survey | 30-07-1978
| Ks | 3.9m Anglo-Australian Telescope | S. Ryder & C. Tinney | 28-07-2002
| R | ANU 40inch Telescope | J.C. O’Brien | 11-07-2002
| V | ANU 40inch Telescope | J.C. O’Brien | 12-07-2002
|  $3.6\mu$m | Spitzer IRAC | K. Sheth | 31-07-2010
|  $4.5\mu$m | Spitzer IRAC | K. Sheth | 31-07-2010
ESO 115-G021 | I | ANU 40inch Telescope | J.C. O’Brien | 10-07-2002
| J | UK 48-inch Schmidt | Digitized Sky Survey | 09-09-1975
| R | CTIO 0.9 meter telescope | J. Funes | 14-09-2001
| V | ANU 40inch Telescope | J.C. O’Brien | 12-07-2002
|  $3.6\mu$m | Spitzer IRAC | R. Kennicutt | 12-09-2007
|  $4.5\mu$m | Spitzer IRAC | R. Kennicutt | 12-09-2007
ESO 138-G014 | B | ESO 1m Schmidt | ESO-LV project |
| H | 2.3m Advanced Technology Telescope | J.C. O’Brien | 16-07-2002
| I | ANU 40inch Telescope | J.C. O’Brien | 10-07-2002
| R | ESO 1m Schmidt | ESO-LV project |
| V | ANU 40inch Telescope | J.C. O’Brien | 12-07-2002
|  $3.6\mu$m | Spitzer IRAC | B. Tully | 09-05-2012
ESO 146-G014 | I | ANU 40inch Telescope | J.C. O’Brien | 10-07-2002
| Ks | 3.9m Anglo-Australian Telescope | S. Ryder & C. Tinney | 28-07-2002
|  $3.6\mu$m | Spitzer IRAC | G. Rieke | 31-10-2006
ESO 274-G001 | J | UK 48-inch Schmidt | Digitized Sky Survey | 14-03-1975
| R | Danish 1.54m | J. Rossa | 01-08-2000
| V | ANU 40inch Telescope | J.C. O’Brien | 12-07-2002
|  $3.6\mu$m | Spitzer IRAC | B. Tully | 10-05-2012
UGC 7321 | I | ANU 40inch Telescope | J.C. O’Brien | 04-03-2002
| J | Palomar 48-inch Schmidt | Digitized Sky Survey | 23-03-1990
| R | ANU 40inch Telescope | J.C. O’Brien | 11-07-2002
|  $3.6\mu$m | Spitzer IRAC | L. Matthews | 26-12-2005
|  $4.5\mu$m | Spitzer IRAC | L. Matthews | 26-12-2005
Table 2: Details of stellar observations

Galaxy | Band | Magnitude | $B/D$ |  $L_{\textrm{d}}$ [$\odot$] |  $L_{\textrm{b}}$ [$\odot$] |  $L_{\textrm{tot}}$ [$\odot$] | $M_{\textrm{HI}}/L_{\textrm{tot}}$ | $\chi^{2}$ | Source
---|---|---|---|---|---|---|---|---|---
IC 2531 | R | 12.5 | 0.01 | 3.49E+09 | 3.49E+07 | 3.52E+09 | 2.1 | 0.47 | Doyle et al. (2005)
| I | 11.9 | 0.07 | 2.97E+09 | 1.99E+08 | 3.17E+09 | 2.3 | 0.18 | Doyle et al. (2005)
| Wise1 |  |  |  |  |  |  | 0.07 |
IC 5052 (left) | B | 11.6 | 0.64 | 2.05E+09 | 1.31E+09 | 3.36E+09 | 0.3 | 0.26 | Doyle et al. (2005)
| H | 9.1 | 2.00 | 9.41E+08 | 1.88E+09 | 2.82E+09 | 0.3 | 0.20 | Jarrett et al. (2003)
| I | 11.4 | 2.00 | 2.23E+08 | 4.46E+08 | 6.69E+08 | 1.3 | 0.14 | Doyle et al. (2005)
| J | 9.7 | 2.00 | 7.70E+08 | 1.54E+09 | 2.31E+09 | 0.4 | 0.13 | Jarrett et al. (2003)
| R | 11.7 | 2.00 | 2.79E+08 | 5.58E+08 | 8.37E+08 | 1.1 | 0.10 | Doyle et al. (2005)
| V | 11.0 | 0.69 | 1.76E+09 | 1.22E+09 | 2.98E+09 | 0.3 | 0.14 | de Vaucouleurs et al. (1991)
| Wise1 |  |  |  |  |  |  | 0.12 |
| Wise2 |  |  |  |  |  |  | 0.16 |
IC 5052 (right) | B | 11.6 | 1.49 | 6.77E+08 | 1.01E+09 | 1.69E+09 | 0.5 | 0.14 | Doyle et al. (2005)
| H | 9.1 | 2.00 | 8.62E+08 | 1.72E+09 | 2.59E+09 | 0.3 | 0.17 | Jarrett et al. (2003)
| I | 11.4 | 1.62 | 1.92E+08 | 3.10E+08 | 5.02E+08 | 1.8 | 0.07 | Doyle et al. (2005)
| J | 9.7 | 2.00 | 6.74E+08 | 1.35E+09 | 2.02E+09 | 0.4 | 0.07 | Jarrett et al. (2003)
| R | 11.7 | 0.93 | 3.46E+08 | 3.21E+08 | 6.67E+08 | 1.3 | 0.08 | Doyle et al. (2005)
| V | 11.0 | 2.00 | 5.96E+08 | 1.19E+09 | 1.79E+09 | 0.5 | 0.06 | de Vaucouleurs et al. (1991)
| Wise1 |  |  |  |  |  |  | 0.07 |
| Wise2 |  |  |  |  |  |  | 0.06 |
IC 5249 | B | 13.9 | 0.26 | 2.33E+09 | 5.96E+08 | 2.93E+09 | 1.9 | 0.42 | Doyle et al. (2005)
| H | 12.3 | 0.85 | 6.40E+08 | 5.42E+08 | 1.18E+09 | 4.7 | 0.18 | Skrutskie et al. (2006)
| I | 13.7 | 0.46 | 5.26E+08 | 2.42E+08 | 7.68E+08 | 7.3 | 0.30 | Doyle et al. (2005)
| J | 13.1 | 0.10 | 7.60E+08 | 7.60E+07 | 8.36E+08 | 6.7 | 0.11 | Skrutskie et al. (2006)
| K | 12.6 | 0.86 | 5.67E+08 | 4.85E+08 | 1.05E+09 | 5.3 | 0.41 | Skrutskie et al. (2006)
| R | 13.9 | 0.72 | 5.37E+08 | 3.86E+08 | 9.23E+08 | 6.1 | 0.11 | Doyle et al. (2005)
| V |  |  |  |  |  |  | 0.06 |
| Wise1 |  |  |  |  |  |  | 0.15 |
| Wise2 |  |  |  |  |  |  | 0.19 |
ESO 115-G021 | I | 13.1 | 2.00 | 1.21E+07 | 2.42E+07 | 3.63E+07 | 17.1 | 0.11 | Doyle et al. (2005)
| J | 14.1 | 0.01 | 7.01E+06 | 7.01E+04 | 7.08E+06 | 87.6 | 0.13 | Jarrett et al. (2003)
| R | 13.1 | 0.54 | 3.21E+07 | 1.75E+07 | 4.96E+07 | 12.5 | 0.08 | Doyle et al. (2005)
| V | 12.6 | 0.58 | 8.89E+07 | 5.18E+07 | 1.41E+08 | 4.4 | 0.15 | de Vaucouleurs & Longo (1988)
| Wise1 | 10.5 | 1.08 | 1.03E+08 | 1.11E+08 | 2.14E+08 | 2.9 | 0.19 | Dale et al. (2009)
| Wise2 | 10.4 | 1.23 | 1.05E+08 | 1.30E+08 | 2.35E+08 | 2.6 | 0.35 | Dale et al. (2009)
ESO 138-G014 | B | 12.8 | 0.10 | 4.17E+09 | 4.04E+08 | 4.57E+09 | 0.6 | 0.32 | Doyle et al. (2005)
| H | 10.6 | 0.30 | 1.98E+09 | 5.88E+08 | 2.57E+09 | 1.1 | 0.43 | Jarrett et al. (2003)
| I | 12.4 | 2.00 | 3.81E+08 | 7.62E+08 | 1.14E+09 | 2.5 | 0.07 | Doyle et al. (2005)
| R | 12.7 | 0.01 | 1.40E+09 | 1.40E+07 | 1.41E+09 | 2.1 | 0.27 | Doyle et al. (2005)
| V |  |  |  |  |  |  | 0.08 |
| Wise1 |  |  |  |  |  |  | 0.14 |
ESO 146-G014 | I | 13.9 | 0.39 | 1.78E+08 | 6.87E+07 | 2.47E+08 | 7.7 | 0.14 | Doyle et al. (2005)
| K |  | 0.87 |  |  |  |  | 1.08 |
| V | 14.6 | 1.98 | 1.23E+08 | 2.43E+08 | 3.66E+08 | 5.2 | 0.17 | Zackrisson et al. (2006)
ESO 274-G001 | V | 10.1 | 0.56 | 9.91E+08 | 5.55E+08 | 1.55E+09 | 0.2 | 0.04 | de Vaucouleurs et al. (1991)
| J | 8.7 | 0.55 | 9.01E+08 | 4.96E+08 | 1.40E+09 | 0.2 | 0.08 | Jarrett et al. (2003)
| R | 10.9 | 0.73 | 2.42E+08 | 1.77E+08 | 4.19E+08 | 0.8 | 0.07 | Doyle et al. (2005)
| Wise1 |  |  |  |  |  |  | 0.13 |
UGC 7321 | R | 12.7 | 1.04 | 2.92E+08 | 3.05E+08 | 5.97E+08 | 1.6 | 0.05 | Taylor et al. (2005)
| I | 12.4 | 1.08 | 2.00E+08 | 2.16E+08 | 4.16E+08 | 2.4 | 0.04 | Makarova (1999)
| J | 11.5 | 0.01 | 5.00E+08 | 5.00E+06 | 5.05E+08 | 1.9 | 0.09 | Jarrett et al. (2003)
| Wise1 | 10.3 | 2.00 | 2.51E+08 | 5.02E+08 | 7.53E+08 | 1.3 | 0.02 | Dale et al. (2009)
| Wise2 | 10.3 | 2.00 | 2.57E+08 | 5.14E+08 | 7.71E+08 | 1.3 | 0.05 | Dale et al. (2009)

Table 3: For each filter band, the $\chi^{2}$ quality of the fit is shown. If
available, the literature brightness is shown together with its source. Where
this is available, the total brightness of the galaxy in that band is
calculated