2013A&A...550A.135A


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST01:35:20

2013A&A...550A.135A - Astronomy and Astrophysics, volume 550A, 135-135 (2013/2-1)

The thermal state of molecular clouds in the Galactic center: evidence for non-photon-driven heating.

AO Y., HENKEL C., MENTEN K.M., REQUENA-TORRES M.A., STANKE T., MAUERSBERGER R., AALTO S., MUEHLE S. and MANGUM J.

Abstract (from CDS):

We used the Atacama Pathfinder Experiment (APEX) 12m telescope to observe the JKAKc=303->202, 322->221, and 321->220 transitions of para-H2CO at 218 GHz simultaneously to determine kinetic temperatures of the dense gas in the central molecular zone (CMZ) of our Galaxy. The map extends over approximately 40'x8' (∼100x20 pc2) along the Galactic plane with a linear resolution of 1.2 pc. The strongest of the three lines, the H2CO (303->202) transition, is found to be widespread, and its emission shows a spatial distribution similar to ammonia. The relative abundance of para-H2CO is 0.5-1.2x10–9, which is consistent with results from lower frequency H2CO absorption lines. Derived gas kinetic temperatures for individual molecular clouds range from 50K to values in excess of 100K. While a systematic trend toward (decreasing) kinetic temperature versus (increasing) angular distance from the Galactic center (GC) is not found, the clouds with highest temperature (Tkin>100K) are all located near the nucleus. For the molecular gas outside the dense clouds, the average kinetic temperature is 65±10K. The high temperatures of molecular clouds on large scales in the GC region may be driven by turbulent energy dissipation and/or cosmic-rays instead of photons. Such a non-photon-driven thermal state of the molecular gas provides an excellent template for the more distant vigorous starbursts found in ultraluminous infrared galaxies (ULIRGs).

Abstract Copyright:

Journal keyword(s): Galaxy: center - ISM: clouds - ISM: molecules - radio lines: ISM

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 2929 2
2 M 42 HII 05 35 17.3 -05 23 28           ~ 3724 0
3 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5331 6
4 NAME Galactic Circumnuclear Disk PoG 17 45 40.0 -29 00 28           ~ 110 0
5 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 3446 3
6 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11533 0
7 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1909 1

    Equat.    Gal    SGal    Ecl

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2020.07.04-01:35:20

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