J/MNRAS/459/2262 Maps of dust distribution in M31 bulge (Dong+, 2016)
High-resolution mapping of dust via extinction in the M31 bulge.
Dong H., Li Z. Y., Wang Q.D., Lauer T.R., Olsen K.A.G., Saha A.,
Dalcanton J.J., Groves B.A.
<Mon. Not. R. Astron. Soc. 459, 2262 (2016)>
=2016MNRAS.459.2262D 2016MNRAS.459.2262D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Interstellar medium ; Extinction ;
Molecular clouds ; Reddening
Keywords: dust, extinction - galaxies: bulges - galaxies: ISM
Abstract:
We map the dust distribution in the central 180" (∼680pc) region of
the M31 bulge, based on HST WFC3 and ACS observations in ten bands
from near-ultraviolet (2700Å) to near-infrared (1.5-micron). This
large wavelength coverage gives us great leverage to detect not only
dense dusty clumps, but also diffuse dusty molecular gas. We fit a
pixel-by-pixel spectral energy distributions to construct a
high-dynamic-range extinction map with unparalleled angular resolution
(∼0.5", i.e., ∼2pc) and sensitivity (the extinction uncertainty,
delta AV∼0.05). In particular, the data allow to directly fit the
fractions of starlight obscured by individual dusty clumps, and hence
their radial distances in the bulge. Most of these clumps seem to be
located in a thin plane, which is tilted with respect to the M31 disk
and appears face-on. We convert the extinction map into a dust mass
surface density map and compare it with that derived from the dust
emission as observed by Herschel. The dust masses in these two maps
are consistent with each other, except in the low-extinction regions,
where the mass inferred from the extinction tends to be
underestimated. Further, we use simulations to show that our method
can be used to measure the masses of dusty clumps in Virgo cluster
early-type galaxies to an accuracy within a factor of ∼2.
Description:
275w.fit, f336w.fit, f390m.fit, f547m.fit and f665n.fit are the
mosaics of HST WFC3/UVIS images at F275W (2704Å), F336W (3355Å),
F390M (3897Å), F547M (5447Å), F665N (6656Å).
f435w.fit, f475w.fit and f814w.fit are the mosaics of HST ACS/WFC
images at F435W (4319Å), F475W (4747Å) and F814W (8057Å).
f110w.fit and f160w.fit are the mosaics of HST WFC3/IR images at F110W
(1.15 micron) and F160W (1.54 micron).
Foreground Galactic extinction (E(B-V)=0.062, i.e. AV=0.17, Schlafly
& Finkbeiner 2011) has been corrected from the ten HST images above.
We have also downgraded the spatial resolution of these images to that
of the F160W, the poorest one. The pixel size of these images are
0.13". Their units are ergs/s/cm2/Å.
These images have also been adaptively smoothed to make sure that each
resolution element has at least 105solar mass.
extin.fit the extinction map (A_F547M) in units of magnitude.
frac.fit the map of the fraction of obscured starlight by the dusty
clumps.
The values are from 0 to 1.0 means that the dusty clumps re far
behind the M31 bulge and 1 means that the clumps are in front of the
M31 bulge pixind.fit the index image for the pixels suffers with
significant extinction in the UV band (such as, F336W, F390M and
F435W) (values = 1). For these pixels, the fractions of obscured
starlight in frac.fit are very reliable.
Objects:
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RA (2000) DE Designation(s)
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00 42 44.33 +41 16 07.5 M31 = NAME ANDROMEDA Nebula
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 87 13 List of fits images
fits/* . 13 Individual fits files
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 34 I5 Kibyte size Size of FITS file
36- 45 A10 --- FileName Name of FITS file, in subdirectory fits
47- 87 A41 --- Title Title of the FITS file
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Acknowledgements:
Hui Dong, dong.dhdxx(at)gmail.com
References:
Dong et al., 2014ApJ...785..136D 2014ApJ...785..136D
Dong et al., 2015MNRAS.451.4126D 2015MNRAS.451.4126D
(End) Hui Dong [IAA-CSIC, Spain], Patricia Vannier [CDS] 16-Apr-2016