J/A+A/664/A174 Galactic interstellar dust Gaia-2MASS 3D maps (Vergely+, 2022)
Three-dimensional extinction maps:
Inverting inter-calibrated extinction catalogs.
Vergely J.L., Lallement R., Cox N.L.J.
<Astron. Astrophys. 664, A174 (2022)>
=2022A&A...664A.174V 2022A&A...664A.174V (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Extinction
Keywords: ISM: clouds - dust, extinction - ISM: structure -
local insterstellar matter
Abstract:
Three-dimensional (3D) maps of the extinction density in the Milky Way
can be built through the inversion of large catalogues of
distance-extinction pairs for individual target stars. Considerable
progress is currently achieved in this field through the Gaia mission.
Available catalogues are based on various types of photometric or
spectrophotometric information and on different techniques of
extinction estimations.
The spatial resolution of the maps that can be achieved increases with
the spatial density of the target stars, and, consequently, with the
combination of input catalogues containing different target lists.
However, this requires careful inter-calibration of the catalogues.
Our aim is to develop methods of inter-comparison and
inter-calibration of two different extinction catalogues.
The catalogue we used as reference for inter-calibration is a
spectrophotometric catalogue. It provides a more accurate extinction
than a purely photometric catalogue. In order to reduce the dimension
of the problem, a principal component analysis was performed in (G,
GB, GR, J, H, K) multi-colour space. The subspace constituted by the
two first components was split into cells in which we estimated the
deviations from the reference. The deviations were computed using all
targets from the reference catalogue that were located at a short
spatial distance of each secondary target. Corrections and filtering
were deduced for each cell in the multi-colour space.
We applied the inter-calibration to two very different extinction
datasets: on the one hand, extinctions based on both spectroscopy and
photometry, representing 6 million objects and serving as a reference,
and, on the other hand, a catalogue of 35 million extinctions based on
photometry of Gaia eDR3 and 2MASS. After calibration, the dispersion
of the extinction among neighbouring points in the second catalogue is
reduced, regardless of whether reference targets are present locally.
Weak structures are then more apparent. The extinction of high
Galactic latitude targets is significantly more tightly correlated
with the dust emission measured by Planck, a property acquired from
the first catalogue. A hierarchical inversion technique was applied to
the two merged inter-calibrated catalogues to produce 3D extinction
density maps corresponding to different volumes and maximum spatial
resolution. The maximum resolution is 10pc for a 3000pcx3000pcx800pc
volume around the Sun, and the maximum size of the maps is
10kpcx10kpcx800pc for a resolution of 50pc. The inclusion of the
spectroscopic survey data increases the dynamic range of the
extinction density, improves the accuracy of the maps, and allows the
mapping to be extended to greater distances to better constrain the
remarkable ∼2.5kpc wide dust-free region in the second quadrant in
particular, which now appears as a giant oval superbubble.
Description:
3D distribution of extinction density at 550nm in a 6kpc by 6kpc by
0.8kpc volume around the Sun. The map is in Cartesian coordinates
with the Sun at centre X,Y,Z=0,0,0. The X axis is directed to the
Galactic Centre, the Y axis is along the direction of rotation, and
the Z axis points to the Northern Galactic Pole. Distances X, Y, Z
units are parsecs. The extinction density is in nanomagnitude per
parsec.
Caution: read the article for assumptions during the inversion
(especially the resolution) and errors at large distances or beyond
very dense structures.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
cube_ext.dat 32 232226561 3D distribution of extinction density at 550nm
in a 6kpc by 6 kpc by 0.8kpc volume around
the Sun
list.dat 149 5 List of fits datacubes
fits/* . 5 Individual fits datacubes
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/350 : Gaia eDR3 (Gaia Collaboration, 2020)
J/A+A/661/A147 : Galactic interstellar dust GaiaDR2-2MASS 3D maps
(Lallement+, 2022)
Byte-by-byte Description of file: cube_ext.dat
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Bytes Format Units Label Explanations
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1- 6 I6 pc X X coordinate
8- 13 I6 pc Y Y coordinate
15- 20 I6 pc Z Z coordinate
22- 31 I10 nmag/pc Exti Extinction density nanomag per pc at (X,Y,Z)
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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- 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 pixels along Z-axis
13- 18 I6 Kibyte size Size of FITS file
20- 60 A41 --- FileName Name of FITS file, in subdirectory fits
62-149 A88 --- Title Title of the FITS file
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Acknowledgements:
Rosine Lallement, Rosine.Lallement(at)obspm.fr
(End) Patricia Vannier [CDS] 10-Aug-2022