2006A&A...448..457U


C.D.S. - SIMBAD4 rel 1.7 - 2019.07.22CEST15:16:01

2006A&A...448..457U - Astronomy and Astrophysics, volume 448, 457-470 (2006/3-3)

Large-scale molecular shocks in galaxies: the SiO interferometer map of IC 342.

USERO A., GARCIA-BURILLO S., MARTIN-PINTADO J., FUENTE A. and NERI R.

Abstract (from CDS):

We present the first high-resolution (5.6"x5.1") images of the emission of silicon monoxide (SiO) in the nucleus of the nearby spiral IC 342, obtained with the IRAM Plateau de Bure Interferometer (PdBI). Using a two-field mosaic, we have simultaneously mapped the emission of the SiO(v=0, J=2-1) and H13CO+(J=1-0) lines in a region of ∼0.9x1.3kpc2 (RAxDec) centered around the nucleus of IC 342. The bulk of the emission in the two lines comes from a ∼290pc spiral arm located to the North and a central component that forms the southern ridge of a r∼80pc nuclear ring that was identified in other interferometer maps of the galaxy. We detect continuum emission at 86.8 GHz in a ∼80-180pc central source. The continuum emission, dominated by thermal free-free bremsstrahlung, is mostly anticorrelated with the observed distribution of SiO clouds. The SiO-to-H13CO+ intensity ratio is seen to increase by an order of magnitude from the nuclear ring (∼0.3) to the spiral arm (∼3.3). Furthermore the gas kinematics show significant differences between SiO and H13CO+ over the spiral arm, where the linewidths of SiO are a factor of 2 larger than those of H13CO+. The average abundance of SiO in the inner r∼320pc of IC 342 is X(SiO)>2x10–10. This shows that shock chemistry is at work in the inner molecular gas reservoir of IC 342. To shed light on the nature of shocks in IC 342, we have compared the emission of SiO with another tracer of molecular shocks: the emission of methanol (CH3OH). We find that the significant difference of the abundance of SiO measured between the spiral arm (X(SiO) ∼ a few 10–9) and the nuclear ring (X(SiO)∼10–10) is not echoed by a comparable variation in the SiO-to-CH3OH intensity ratio. This implies that the typical shock velocities should be similar in the two regions. In contrast, the fraction of shocked molecular gas should be ∼5-7 times larger in the spiral arm (up to ∼10% of the available molecular gas mass over the arm region) compared to the nuclear ring. In the light of these results, we revise the validity of the various scenarios that have been proposed to explain the onset of shock chemistry in galaxies and study their applicability to the nucleus of IC 342. We conclude that the large-scale shocks revealed by the SiO map of IC 342 are mostly unrelated to star formation and arise instead in a pre-starburst phase. Shocks are driven by cloud-cloud collisions along the potential well of the IC 342 bar. The general implications for the current understanding of galaxy evolution are discussed.

Abstract Copyright:

Journal keyword(s): galaxies: individual: IC 342 - galaxies: starburst - galaxies: nuclei - ISM: molecules - molecular processes - radio lines: galaxies

Simbad objects: 27

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Number of rows : 27

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 LBN 119.83-06.05 MoC 00 28 43.5075 +56 41 56.868           ~ 63 0
2 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 2839 2
3 6C 022440+670742 QSO 02 28 50.05148948 +67 21 03.0293039   19.5   18.1   ~ 223 1
4 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 3952 2
5 [DRG92] E Cld 03 46 47.53 +68 05 43.5           ~ 10 0
6 [DRG92] B Cld 03 46 47.85 +68 05 46.5           ~ 13 0
7 IC 342 SBG 03 46 48.514 +68 05 45.98   10.5       ~ 1356 1
8 [DRG92] A Cld 03 46 48.55 +68 05 43.6           ~ 13 0
9 [DRG92] D Cld 03 46 48.94 +68 05 56.8           ~ 9 0
10 [DRG92] C Cld 03 46 49.16 +68 05 50.8           ~ 11 0
11 OMC 3 MoC 05 35 20.0 -05 01 00           ~ 211 1
12 OMC 2 MoC 05 35 27 -05 10.1           ~ 372 1
13 M 78 RNe 05 46 45.8 +00 04 45   8.0       ~ 331 0
14 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5183 6
15 NGC 4038 GiP 12 01 53.002 -18 52 03.32   10.91   9.74 11.0 ~ 1257 1
16 NAME Antennae IG 12 01 53.170 -18 52 37.92           ~ 1521 0
17 NGC 4039 GiP 12 01 53.8 -18 53 06   11.08   9.77   ~ 1119 1
18 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2597 4
19 3C 345 QSO 16 42 58.8100340220 +39 48 36.999540578   16.81 16.59 16.84   ~ 1525 2
20 NGC 6240 Sy2 16 52 58.861 +02 24 03.55   14.31 13.37     ~ 1428 2
21 NAME Sgr C MoC 17 44 36.3 -29 28 13           ~ 296 0
22 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 10860 0
23 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1830 1
24 EM* MWC 349 Em* 20 32 45.6328 +40 39 36.143   15.88 13.15 12.13   Bep 681 1
25 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 456 0
26 NAME NGC 7129 FIR 2 IR 21 44 01.5 +66 03 40           ~ 79 0
27 3C 454.3 QSO 22 53 57.74798 +16 08 53.5611   16.57 16.10 15.22   ~ 2422 2

    Equat.    Gal    SGal    Ecl

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2019.07.22-15:16:01

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