2016A&A...592L...3K


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.11CEST21:18:43

2016A&A...592L...3K - Astronomy and Astrophysics, volume 592, L3-3 (2016/8-1)

ACA [CI] observations of the starburst galaxy NGC 253.

KRIPS M., MARTIN S., SAKAMOTO K., AALTO S., BISBAS T.G., BOLATTO A.D., DOWNES D., ECKART A., FERUGLIO C., GARCIA-BURILLO S., GEACH J., GREVE T.R., KONIG S., MATSUSHITA S., NERI R., OFFNER S., PECK A.B., VITI S. and WAGG J.

Abstract (from CDS):

Context. Carbon monoxide (CO) is widely used as a tracer of the molecular gas in almost all types of environments. However, several shortcomings of CO complicate usaging it as H2 tracer, such as its optical depth effects, the dependence of its abundance on metallicity, or its susceptibility to dissociation in highly irradiated regions. Neutral carbon emission has been proposed to overcome some of these shortcomings and hence to help revealing the limits of CO as a measure of the molecular gas.
Aims. We aim to study the general characteristics of the spatially and spectrally resolved carbon line emission in a variety of extragalactic sources and evaluate its potential as complementary H2 tracer to CO.
Methods. We used the Atacama Compact Array to map the [CI](3P1-3P0) line emission in the nearby starburst galaxy NGC 253 at unprecedented angular resolution (∼3''). This is the first well-resolved interferometric [CI] map of an extragalactic source.
Results. We have detected the [CI] line emission at high significance levels along the central disk of NGC 253 and its edges where expanding shells have previously been found in CO. Globally, the distribution of the [CI] line emission strongly resembles that of CO, confirming the results of previous Galactic surveys that [CI] traces the same molecular gas as CO. However, we also identify a significant increase of [CI] line emission with respect to CO in (some of) the outflow or shocked regions of NGC 253, namely the bipolar outflow emerging from the nucleus. A first-order estimate of the [CI] column densities indicates abundances of [CI] that are very similar to the abundance of CO in NGC 253. Interestingly, we find that the [CI] line is marginally optically thick within the disk.
Conclusions. The enhancement of the [CI]/CO line ratios (∼0.4-0.6) with respect to Galactic values (≤0.1), especially in the shocked regions of NGC 253, clearly indicates that mechanical perturbation such as shocks and the strong radiation fields in this starburst galaxy have a marked effect on the carbon excitation and/or abundance.

Abstract Copyright: © ESO, 2016

Journal keyword(s): galaxies: active - submillimeter: galaxies - galaxies: ISM - galaxies: starburst - galaxies: individual: NGC 253

Simbad objects: 5

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Number of rows : 5

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 QSO B0035-252 QSO 00 38 14.7354970 -24 59 02.235519   18.90   17.14   ~ 97 1
2 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 3022 2
3 NAME Galactic Center gam 17 45 39.60213 -29 00 22.0000           ~ 12174 0
4 3C 454.3 Bla 22 53 57.74798 +16 08 53.5611   16.57 16.10 15.22   ~ 2570 2
5 NAME Local Group GrG ~ ~           ~ 7259 0

    Equat.    Gal    SGal    Ecl

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2021.05.11-21:18:43

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