J/A+A/655/A64 Galactic CO maps (Mertsch+, 2021)
Bayesian inference of three-dimensional gas maps: I. Galactic CO.
Mertsch P., Vittino A.
<Astron. Astrophys. 655, A64 (2021)>
=2021A&A...655A..64M 2021A&A...655A..64M (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Carbon monoxide ; Models
Keywords: Galaxy: structure - ISM: kinematics and dynamics - ISM: molecules -
methods: statistical
Abstract:
Carbon monoxide (CO) is the best tracer of Galactic molecular hydrogen
H2. Its lowest rotational emission lines are in the radio regime,
and thanks to Galactic rotation, emission at different distances is
Doppler shifted. For a given gas flow model, the observed spectra can
thus be deprojected along the line of sight to infer the gas
distribution. We used the CO-line survey of Dame et al.
(2001ApJ...547..792D 2001ApJ...547..792D) to reconstruct the three-dimensional density of
H2. We considered the deprojection as a Bayesian variational
inference problem. The posterior distribution of the gas densities
allowed us to estimate the mean and uncertainty of the reconstructed
density. Unlike most of the previous attempts, we took the
correlations of gas on a variety of scales into account, which allowed
us to correct for some of the well-known pathologies, such as
finger-of-god effects. The two gas flow models that we adopted
incorporate a Galactic bar that induces radial motions in the inner
few kiloparsecs and thus offers spectral resolution towards the
Galactic centre. We compared our gas maps with those of earlier
studies and characterise their statistical properties, for instance
the radial profile of the average surface mass density. We have made
our three-dimensional gas maps and their uncertainties available to
the community here and at https://dx.doi.org/10.5281/zenodo.5501196.
Description:
Here, we provide the mean and standard deviation of the gas density
(in cm-3) on a three-dimensional 512x512x16 grid, spanning
-16kpc<x<16kpc, 16kpc<y<16kpc and -0.5kpc<z<0.5kpc, both for the BEG03
and the SBM15 gas flow models. In addition, we also publish the mean
and standard deviation of the mass surface density (in M☉/pc2)
on a two-dimensional 512x512 grid, spanning -16kpc<x<16kpc and
16kpc<y<16kpc, again for both gas flow models.
Throughout, we have assumed an CO-to-H2 conversion factor
XCO=2*1020molecules/cm2(K.km/s)-1. Refer to the FITS headers for
more detailed information and see arXiv:2012.15770 for a detailed
description of the reconstruction as well as a comparison with earlier
studies.
When using the deprojected gas maps in your research work, please
refer to the CDS and the following publication P. Mertsch and A.
Vittino, "Bayesian inference of three-dimensional gas maps: I.
Galactic CO", arXiv:2012.15770.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 154 8 List of fits files
fits/* . 8 Individual fits files
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Nx Number of pixels along X-axis
5- 7 I3 --- Ny Number of pixels along Y-axis
9- 11 I3 --- Nz ? Number of slices
13- 20 F8.4 kpc bx Lower value of X position
22- 29 F8.4 kpc Bx Upper value of X position
31- 36 F6.4 kpc dx X position resolution
38- 45 F8.4 kpc by Lower value of Y position
47- 53 F7.4 kpc By Upper value of Y position
55- 60 F6.4 kpc dy Y position resolution
62- 69 F8.5 kpc bz ? Lower value of Z position
71- 77 F7.4 kpc Bz ? Upper value of Z position
79- 84 F6.4 kpc dz ? Z position resolution
86- 90 I5 Kibyte size Size of FITS file
92-103 A12 --- FileName Name of FITS file, in subdirectory fits
105-154 A50 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Philipp Mertsch, pmertsch(at)physik.rwth-aachen.de
(End) Patricia Vannier [CDS] 13-Sep-2021