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Notes for object NGC 3044

11 note(s) found in NED.


1. 2003ApJS..148..383M
Re:NGC 3044
A11. NGC 3044 Like NGC 2820, NGC 3044 is an SB(s)c galaxy seen
essentially edge-on (90deg). NGC 3044 was observed with the WHT/TTF and
at CTIO; the resulting H{alpha}, [N II], and H{alpha}+[N II] images are
presented in Figure 11. Most remarkable in the WHT image is the arc of
emission (with an EM ~20 pc cm^-6^) seen rising above the disk into the
southern halo. Located about 1 kpc west of the nucleus, the arc is over
1 kpc in diameter and extends ~1.5 kpc into the halo. This is most
likely an expanding super-bubble seen in projection. Another arc of
H{alpha} emission is detected ~7 kpc east of the nucleus with an EM of
20-35 pc cm^-6^. This feature extends ~1 kpc into the halo. A more
widespread layer of diffuse gas is also detected on both sides of the
galaxy, extending upward to a height of ~3 kpc.
The total H{alpha} luminosity /D^2^_25_ 10 x 10^37^ ergs s^-1^ kpc^-2^,
16% of which is attributed to extraplanar gas. The scale height of the
gas on the north side (4.7 kpc) is greater than that on the south side
(2.6 kpc; based on the CTIO observations). The ionized mass associated
with this extraplanar gas is 2.0 x 10^8^ M_{sun}_, higher than most
galaxies. The strong correlation between disk and north halo gas, but
the small 1 {sigma} deviation of the extraplanar emission from the
average vertical profile (based on the WHT observations), suggest that
the extensive extraplanar emission observed in the northern halo
originates from HII regions in the disk of the galaxy but is not
concentrated over them (although the H{alpha} intensity is somewhat
higher in these regions). The locations of the apparent bubbles
extending into the southern halo do not appear to correlate with the
H II regions in the disk of the galaxy, perhaps an indication that the H II
regions in this region have had time to disappear since the supernovae
events took place in the disk.
Rossa & Dettmar (2000) detect an extraplanar layer of DIG emission, but
while we detect eDIG up to a height of 3 kpc, they detect it only up to
a height of ~1 kpc. They also detect several plumes of emission. Rossa &
Dettmar also detect the extended arc structure south of the disk of the
galaxy. They measure an H{alpha} luminosity of 1.3 x 10^41^ ergs s^-1^,
slightly higher, but not significantly so, than ours. Collins et
al. (2000) also observed NGC 3044 and detected similar features
including an extensive extraplanar layer of DIG emission.
Mismatch in the central wavelengths of the H{alpha} and [N II] images
causes a radial gradient in the ratio map. Nevertheless, a slight
vertical gradient also appears to be present in [N II]/H{alpha}, in
agreement with the spectroscopic results of Otte & Dettmar (1999).

2. 2000ApJ...536..645C
Re:NGC 3044
The continuum image shown in Figure 2a shows a nearly edge-on disk with
a prominent dust lane appearing on the southern edge of the galaxy. The
image shows a possible asymmetric distribution of matter, as the
northwest side of the galaxy appears significantly brighter than the
southeast side.
This asymmetry is even more apparent in the H{alpha} image of Figure
2a, as the southeastern side shows very little emission, caused in part
by an oversubtracted continuum level. However, even if the continuum
subtraction were correct in this region, the asymmetry would still
exist. The asymmetry is not due to poor response of the filter to
emission on the southeast, receding side of the galaxy. Emission on both
the northwest (approaching) and southeast sides of the galaxy are within
the filter's peak response region. The image has very little [N II]
contamination, as the throughput of both lines is low. The diffuse
emission can be better seen in the overlays of Figure 10 where the image
has been smoothed to 2 ". The image shows extensive diffuse emission
concentrated mainly above the bulge of the galaxy, possibly tracing out
a central starburst. This region covers about 7 kpc of the disk around
the bulge and is detectable out to z = 4 kpc above and below the disk.
At z = 1 kpc, the brightness of the layer averages about
EM = 25 pc cm^-6^. At R = 1-2 kpc on the northwestern side, a prominent
shell extends to a height of about z = 1.5 kpc below the disk. The
filaments in the shell average around EM = 35 pc cm^-6^ and appear to
form a nearly closed loop, as seen in Figure 2b. However, the shell is
fairly clumped in appearance and may just be a collection of H II
regions below the midplane. Faint emission is present outside of the
central region as well, with the most extended filament, at R = 5 kpc on
the northwestern side, extending to about z = 4 kpc above the disk.

3. 2000ApJ...536..645C
Re:NGC 3044
The throughput of the [N II] lines is low: that of the [N II] 6548 A
line is <~ 40%, while the stronger [N II] 6583A line is ~10%. Thus, we
ignore [N II] emission in modeling the profiles. The Lee & Irwin (1997)
value of i = 85^deg^ is used for the model. We concentrate on modeling
the central region where a bright, smooth extraplanar layer of DIG
occurs.
A profile within this central region, at R = 0-2 kpc on the east side,
is shown in Figure 6a. For the model, we take R0 = 4 kpc, the radial
half-width of the extended layer. A range of parameters provide a good
fit to the profile, from _0_ = 0.007 cm^-6^ and H = 1050 pc
(the model shown) to _0_ = 0.004 cm^-6^ and H = 1500 pc.
The profile for R = 0-1.5 kpc on the west side is shown in Figure 6b.
This profile is also within the central region of extended emission;
thus, we again assume R0 = 4 kpc. A prominent shell extends off the disk
to the south (+z) side, seen as a prominent spike in the profile at
z = 1500 pc. Thus, we model only the north (-z) side, where parameters
ranging from _0_ = 0.006 cm^-6^ and H = 1200 pc to
_0_ = 0.009 cm^-6^ and H = 1000 pc (the model shown) fit the
profile well.

4. 2000ApJ...536..645C
Re:NGC 3044
NGC 3044 has been observed in H I by Lee & Irwin (1997), who detected
numerous neutral hydrogen spurs and supershells. Radio continuum
emission has been detected up to z = 8 kpc by Sorathia (1994). Lee &
Irwin report that H I and radio continuum emission, in many cases, do
appear to be well correlated. Figure 10 shows the H{alpha} image, with
H I column density and 20 cm radio continuum contour overlays. Beam
sizes of the H I and radio continuum maps are 21" x 20" and 19" x 16",
respectively. To enhance filamentary emission, the H{alpha} image has
been smoothed with a 2" Gaussian.
It is interesting that the H{alpha} and radio continuum halos have a
very similar structure in general. In fact, the H{alpha}-emitting disk
and radio continuum halo terminate at the same radial location, though
the H I disk continues to the east. This is consistent with a model
where cosmic rays in the upper halo have their source in the
supernova-rich H II region layer. In addition, a radio-bright region of
the disk, at R = 5 kpc west of center, likely marks a star-forming
region, as both an extraplanar DIG filament and an H I supershell
originate at this location.
The bright central region of extraplanar DIG can be correlated with H I
and radio continuum features. The southern spur of enhanced H I column
density appears associated with the central region of DIG, though they
are slightly offset. Within this area, the loop of H{alpha} emission,
better seen in Figure 2b, is in the proximity of a feature identified as
an expanding H I supershell. The H{alpha} loop is centered at a position
23" north and 4" east (or 1.8 kpc) of the center of the H I supershell.
There appears to be some overlap of these features, as the radius of the
H{alpha} loop is roughly 1 kpc, while the H I shell has a radius of 1.7
kpc (Lee & Irwin 1997). A spur of enhanced radio continuum emission
passes through this region as well. North of the disk, two H I spurs
occur above the central region of DIG, where a prominent radio continuum
spur also originates. The northern H I feature at R = 5 kpc west of
center, identified by Lee & Irwin as the most massive and energetic of
the H I supershells, is associated with a faint filament of DIG as well
as a radio continuum spur. In displaying correlations between the three
tracers, this feature, marked with an arrow in Figure 10, is the most
likely candidate for a chimney in this galaxy.

5. 2000ApJ...536..645C
Re:NGC 3044
Scale Heights of Extraplanar Features
In this section, we compare the vertical extent of H{alpha}, H I, and
20 cm radio continuum emission perpendicular to the major axes of
NGC 5775 and NGC 3044. Again, the low inclination of NGC 3556 prevents a
detailed analysis of emission scale height. For regions of interest,
vertical profiles covering the radial extent of the region are extracted
and averaged over that range. We concentrate on modeling areas where a
prominent extraplanar feature is apparent in all three tracers, though
we do model other regions as well. In comparing scale heights of a
certain feature, we attempt to obtain vertical profiles covering the
same radial range in all three tracers. In some cases, however, DIG and
radio continuum filaments are not perfectly aligned, resulting in
vertical profiles extracted from slightly different regions.
Our approach is similar to that used in the modeling of section 4. The
method considers a model with a single exponential in the z-direction,
of which the peak and scale height, H, can be varied. The model is
placed at the inclination quoted in Table 2, and a model profile is
generated, which we attempt to fit by eye to the data. For the H{alpha}
profiles, we attempt, as before, to fit the model to the data above the
H II region layer. DIB98 found that radio continuum emission profiles of
NGC 5775 can be fitted only by a superposition of a disk component of
small scale height and a halo component of greater extent. Thus, we
attempt to fit the 20 cm radio continuum emission profiles in regions
above where the disk component may contribute to the total emission.
Results of the modeling are listed in Table 3. Three of the profiles
taken from NGC 5775 are of features we have identified as possible
chimneys: the northeast filament, the southwest filament, and the
southeast filament. H{alpha}, 20 cm, and H I profiles of the northeast
filament are shown in Figure 12. The profiles taken from the regions
R = 0-2 (north) and R = 8-10 kpc (south), modeled previously in section
4, are areas where the DIG layer is relatively smooth in appearance. We
also model a region with a very prominent radio continuum filament,
extending to the west at R = 6 kpc north of center, where only low-level
extraplanar H{alpha} emission is detectable. Profiles of this region
are shown in Figure 13. Our models show that the DIG emission generally
has a greater scale height than radio continuum emission for the
prominent DIG filaments in NGC 5775. It is clear, however, that the
scale height of the radio continuum halo is greater in regions without
prominent DIG filaments. H I profiles taken from this galaxy seem to be
poorly fit by an exponential distribution. However, the rapid fall-off
of H I column density at high z does suggest that neutral hydrogen does
not extend as high as DIG filaments or radio continuum emission.
For NGC 3044, we model the west filament, as well as the widespread,
smooth layer of DIG above the central region of the galaxy. Profiles of
the west filament are shown in Figure 14. Our modeling shows DIG and H I
emission are of comparable scale height in NGC 3044 where extraplanar
DIG is present. Twenty cm scale heights could not be reliably determined
because of significant negative data values in that image, such as in
Figure 14b.

6. 2000AJ....119.1592I
Re:NGC 3044
NGC 3044 is an apparently isolated galaxy (Solomon & Sage 1988)
which shows an asymmetric H I distribution as well as kiloparsec-scale
neutral hydrogen arcs extending away from the major axis (Lee & Irwin
1997). Some of the H I features have the signature of expanding
(partial) shells. The implied input energies range up to about 10^56^
ergs, under the assumption of energy input via clustered supernovae and
stellar winds. The H I distribution on the northwest major axis is the
most disturbed, with the H I appearing truncated and not reaching
terminal velocity on this side.
Our radio continuum image shows complex structure which resembles
the H{alpha} + N [II] distribution as imaged by Lehnert & Heckman
(1995). The gap in the radio continuum emission about 14" (1.5 kpc) to
the northwest of center occurs roughly at an H{alpha} minimum, and there
is an H{alpha} peak in the region of the open-topped radio continuum
loop on the major axis about 20" (2 kpc) northwest of center. The
optical images show no evidence for extended emission-line gas along the
minor axis. The radio continuum extension to the north of the nucleus
may be related to a larger radio "spur" seen in lower resolution images
(Condon et al. 1990; Paper I; Colbert et al. 1996).
The radio continuum loop 20" to the northwest is elongated
perpendicular to the major axis with dimensions about 5.52" x 9.51"
(0.58 kpc x 1.0 kpc) in projection. If this loop were in the plane of
the galaxy, its long axis would correspond to roughly 14 kpc, using the
mean inclination of 86^deg^ (Paper I). Thus, we suspect that this loop
is oriented perpendicular to the plane and has been formed as a result
of activity in the vicinity of the hot stars that have formed the H II
regions below it. Since the loop is isolated, we have computed its flux
density, which is 2.9 +/- 0.1 mJy, corresponding to a radio power of
1.6 x 10^20^ W Hz^-1^. This is about the power of 37 median M82
supernova remnants or less than 2 maximum M82 supernova remnants.
Several H I extensions (e.g., features 2, 3, 7, and 8 of Lee & Irwin
1997) above and below the plane have been cataloged in the vicinity of
this loop, but it is not yet possible to tell if any are directly
associated with it.

7. 1996ApJ...467..551C
Re:NGC 3044
3.2.3. NGC 3044
In Figure 2c, we display contour maps of the radio emission from this galaxy.
As in the other starburst galaxies in our sample, much of the radio emission
from this galaxy comes from the disk component. The disk in NGC 3044 is highly
inclined, and it is easy to confirm the presence of a radio halo extending
above the disk (e.g., see our tapered image). This radio halo has been
previously noted by Hummel & van der Hulst (1989). The 1.5 GHz map from Condon
et al. (1990, reproduced in Fig. 2c) clearly shows emission from this radio
halo.

8. 1994CAG1..B...0000S
Re:NGC 3044
Scd(on edge)
CD-1460-S/Br
May 10/11, 1980
103aO + GG385
45 min
NGC 3044 is nearly edge on. It has neither
a central bulge nor luminous halo. A few
individual knots are either HII regions or
individual brightest stars. The magnitude of the
brightest of these is about B = 21.5. The largest
HII region resolves into a disk at about the 2"
level.
The redshift is v_o = 1206 km/s.

9. 1976RC2...C...0000d
Re:NGC 3044
Mass Determination and M/L:
Bull. A.A.S., 1, 186, 1969.

10. 1973UGC...C...0000N
Re:UGC 05311
SB(s)c? (de Vaucouleurs)

11. 1964RC1...C...0000d
Re:NGC 3044
No definite nucleus. Bright knotty center. Poorly resolved.


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