J/ApJ/897/89 1482 Gaussian clumps in the Central Molecular Zone (Li+, 2020)
A Mean Density of 112M☉/pc3 for Central Molecular Zone Clumps-Evidences
for Shear-enabled Pressure Equilibrium in the Galactic Center.
Li G.-X., Zhang C.-P.
<Astrophys. J., 897, 89 (2020)>
=2020ApJ...897...89L 2020ApJ...897...89L
ADC_Keywords: Milky Way; Galactic center; Interstellar medium;
Star Forming Region; Photometry, RI
Keywords: Galactic center ; Interstellar medium ; Star formation ;
Tidal interaction ; Gravitational collapse
Abstract:
We carry out a systematic study of the density structure of gas in the
Central Molecular Zone (CMZ) in the Galactic center by extracting
clumps from the APEX Telescope Large Area Survey of the Galaxy survey
at 870µm. We find that the clumps follow a scaling of
m=ρ0r3, which corresponds to a characteristic density of
nH2=1.6x103/cm3 (ρ0=112M☉/pc3) with a variation of
∼0.5dex, where we assumed a gas-to-dust mass ratio of 100. This
characteristic density can be interpreted as the result of thermal
pressure equilibrium between the molecular gas and the warm ambient
interstellar medium. Such an equilibrium can plausibly be established
since shear has approximately the same strength as self-gravity. Our
findings may explain the fact that star formation in the CMZ is highly
inefficient compared to the rest of the Milky Way disk. We also
identify a population of clumps whose densities are two orders of
magnitudes higher in the vicinity of the Sgr B2 region, which we
propose are produced by collisions between the clumps of lower
densities. For these collisions to occur, processes such as
compressive tides probably have created the appropriate condition by
assembling the clumps together.
Description:
In this paper, we study the density structure of the CMZ region using
data from the Atacama Pathfinder Experiment (APEX) Telescope Large
Area Survey of the Galaxy (ATLASGAL). ATLASGAL is a survey of the
inner Galaxy at 870µm performed by the APEX telescope. It has a
spatial resolution of around 19".
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 84 1482 Parameters of identified Gaussian clumps
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See also:
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008)
J/ApJ/721/137 : The Bolocam Galactic Plane Survey (BGPS) (Bally+, 2010)
J/ApJ/723/492 : Physical properties of GRS molecular clouds (Roman-Duval+,2010)
J/MNRAS/435/400 : ATLASGAL. Properties of compact HII regions (Urquhart+, 2013)
J/A+A/565/A75 : ATLASGAL: dust condensations in Galactic plane (Csengeri+,2014)
J/PASJ/67/90 : Central Molecular Zone in H13CO+ (Tsuboi+, 2015)
J/A+A/586/A50 : Central Molecular Zone H2CO temperature maps (Ginsburg+, 2016)
J/A+A/591/A149 : Hi-GAL. inner Milky Way: +68≥l≥70 (Molinari+, 2016)
J/A+A/598/A76 : Six infrared dark clouds multi-wavelength obs. (Zhang+, 2017)
J/A+A/619/A166 : SEDIGISM, kinematics of ATLASGAL filaments (Mattern+, 2018)
J/ApJS/236/49 : CO and 850um obs. of Planck Galactic cold clumps (Zhang+, 2018)
J/A+A/627/A85 : 8 massive proto-cluster clumps observations (Zhang+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Clumps [1/1482] Clumps number
6- 12 F7.4 deg GLON [-2.01/2] Clump Galactic Longitude
14- 20 F7.4 deg GLAT [-0.41/0.41] Clump Galactic Latitude
22- 26 F5.1 arcsec FWHM [19.3/117.8] Extracted clump size
28- 32 F5.2 pc Rad [0.45/2.74] Clump effective radius
34- 37 F4.1 K Tdust [15.2/36.2] Dust temperature
39- 41 F3.1 K e_Tdust [1.5/3.6] Uncertainty in Tdust
43- 48 F6.2 Jy/beam F870 [0.39/139.9] Peak 870um Flux Density
50- 55 F6.2 Jy S870 [0.54/405.4] Integrated 870um Flux
57- 61 F5.1 10+3Msun MH2 [0.1/116] Mass in molecular hydrogen (1)
63- 66 F4.1 10+3Msun e_MH2 [0.0/16.9] Uncertainty in MH2
68- 71 F4.1 10+23cm-2 NH2 [0.1/29] Molecular hydrogen column density (1)
73- 75 F3.1 10+23cm-2 e_NH2 [0.0/4.0] Uncertainty in nH2
77- 80 F4.1 10+4cm-3 n [0.1/51.9] Number density from S870um
82- 84 F3.1 10+4cm-3 e_n [0.0/7.2] Uncertainty in n
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Note (1): From S870um.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 28-Sep-2021