2015A&A...578A..53C


Query : 2015A&A...578A..53C

2015A&A...578A..53C - Astronomy and Astrophysics, volume 578A, 53-53 (2015/6-1)

The Herschel Dwarf Galaxy Survey. I. Properties of the low-metallicity ISM from PACS spectroscopy.

CORMIER D., MADDEN S.C., LEBOUTEILLER V., ABEL N., HONY S., GALLIANO F., REMY-RUYER A., BIGIEL F., BAES M., BOSELLI A., CHEVANCE M., COORAY A., DE LOOZE I., DOUBLIER V., GALAMETZ M., HUGHES T., KARCZEWSKI O.L., LEE M.-Y., LU N. and SPINOGLIO L.

Abstract (from CDS):

The far-infrared (FIR) lines are important tracers of the cooling and physical conditions of the interstellar medium (ISM) and are rapidly becoming workhorse diagnostics for galaxies throughout the universe. There are clear indications of a different behavior of these lines at low metallicity that needs to be explored. Our goal is to explain the main differences and trends observed in the FIR line emission of dwarf galaxies compared to more metal-rich galaxies, and how this translates in ISM properties. We present Herschel/PACS spectroscopic observations of the [CII] 157µm, [OI] 63 and 145µm, [OIII] 88µm, [NII] 122 and 205µm, and [NIII] 57µm fine-structure cooling lines in a sample of 48 low-metallicity star-forming galaxies of the guaranteed time key program Dwarf Galaxy Survey. We correlate PACS line ratios and line-to-LTIR ratios with LTIR, LTIR/LB, metallicity, and FIR color, and interpret the observed trends in terms of ISM conditions and phase filling factors with Cloudy radiative transfer models. We find that the FIR lines together account for up to 3 percent of LTIR and that star-forming regions dominate the overall emission in dwarf galaxies. Compared to metal-rich galaxies, the ratios of [OIII]88/[NII]122 and [NIII]57/[NII]122 are high, indicative of hard radiation fields. In the photodissociation region (PDR), the [CII]157/[OI]63 ratio is slightly higher than in metal-rich galaxies, with a small increase with metallicity, and the [OI]145/[OI]63 ratio is generally lower than 0.1, demonstrating that optical depth effects should be small on the scales probed. The [OIII]88/[OI]63 ratio can be used as an indicator of the ionized gas/PDR filling factor, and is found to be ∼4 times higher in the dwarfs than in metal-rich galaxies. The high [CII]/LTIR, [OI]/LTIR, and [OIII]/LTIR ratios, which decrease with increasing LTIR and LTIR/LB, are interpreted as a combination of moderate far-UV fields and a low PDR covering factor. Harboring compact phases of a low filling factor and a large volume filling factor of diffuse gas, the ISM of low-metallicity dwarf galaxies has a more porous structure than that of metal-rich galaxies.

Abstract Copyright:

Journal keyword(s): galaxies: dwarf - infrared: ISM - photon-dominated region (PDR) - techniques: spectroscopic - radiative transfer - HII regions

VizieR on-line data: <Available at CDS (J/A+A/578/A53): table4a.dat table4b.dat list.dat dgs_atlas.pdf>

Simbad objects: 63

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Number of rows : 63
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 HS 0017+1055 G 00 20 21.0 +11 12 21           ~ 19 0
2 IC 10 G 00 20 25.50 +59 17 17.0   13.6 9.5     ~ 1101 1
3 ESO 350-38 AGN 00 36 52.489 -33 33 17.23   14.31 14.41 13.49   ~ 360 0
4 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10841 1
5 SDSS J005456.38+255307.8 G 00 54 56.387 +25 53 07.85           ~ 21 0
6 SNR B0057-72.2 SNR 00 59 27.40 -72 10 10.7   12.37 12.57     ~ 238 0
7 NGC 450 H2G 01 15 30.4565036568 -00 51 39.125259576   13.4   13.3 13.2 ~ 223 0
8 NGC 625 AGN 01 35 04.632 -41 26 10.32 12.37 11.78 11.25 11.03 11.5 ~ 279 2
9 UGCA 20 bCG 01 43 14.6 +19 58 51   16       ~ 54 0
10 Z 412-24 H2G 01 44 41.3 +04 53 26 15.07 15.50 15.16 14.86 14.58 ~ 93 0
11 NGC 1140 EmG 02 54 33.5271666624 -10 01 43.142143908 12.41 12.84 12.49 13.6 13.5 ~ 280 1
12 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6825 1
13 SBSG 0335-052 bCG 03 37 44.04 -05 02 38.5     16.65     ~ 462 1
14 NGC 1569 IG 04 30 49.186 +64 50 52.52 11.72 11.86 11.03     ~ 1228 3
15 NGC 1705 SBG 04 54 13.4661493464 -53 21 39.471592428 12.32 12.96 12.56 12.58 12.9 ~ 647 1
16 LHA 120-N 11I HII 04 55 50 -66 34.4           ~ 19 0
17 NGC 1763 As* 04 56 51.5 -66 24 25     9.40     ~ 162 3
18 HD 32340 Em* 04 57 16.253 -66 23 20.94   13.11 12.45 14.00   O3-O6V 77 0
19 NGC 1769 As* 04 57 44.5 -66 27 42           ~ 70 2
20 NGC 1741 IG 05 01 38.3 -04 15 25   13.7   13.02 13.6 ~ 259 0
21 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16978 1
22 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 841 0
23 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1955 1
24 LHA 120-N 158 HII 05 39 11.220 -69 30 13.65           ~ 84 0
25 LHA 120-N 159 HII 05 39 46.650 -69 45 39.94           ~ 273 2
26 LHA 120-N 160 EmO 05 39 47.9 -69 37 08           ~ 117 1
27 LHA 120-N 159S MoC 05 40 03.750 -69 51 01.62           ~ 43 0
28 UGCA 116 H2G 05 55 42.645 +03 23 32.23 10.74 11.68 11.46   11.82 ~ 530 0
29 SCHG 0618-402 H2G 06 20 03.8353 -40 16 42.997           ~ 26 0
30 NGC 2366 H2G 07 28 51.85 +69 12 31.1 12.25 11.86 11.39 11.33   ~ 753 0
31 LEDA 2790884 bCG 08 25 55.5166210656 +35 32 31.833368556   18.2       ~ 114 1
32 ESO 495-21 bCG 08 36 15.190 -26 24 33.66 12.04 11.93 11.45 11.09 12.3 ~ 556 3
33 UGC 4483 GiG 08 37 03.29 +69 46 29.2 15.70 15.46 14.98 14.89   ~ 292 0
34 Mrk 116 PaG 09 34 02.1 +55 14 25           ~ 1087 1
35 Mrk 33 IG 10 32 31.956 +54 24 03.53 13.29 13.66 13.13 12.71 12.27 ~ 356 1
36 NGC 3353 AGN 10 45 22.390 +55 57 37.36 12.90 13.25 12.79     ~ 349 1
37 Mrk 153 G 10 49 05.0478242832 +52 20 07.788652296   14.6       ~ 78 0
38 UGC 6456 bCG 11 28 00.43 +78 59 38.4   14.50       ~ 327 1
39 Mrk 1450 H2G 11 38 35.6552554896 +57 52 26.636623644   15.5       ~ 116 1
40 Mrk 1304 IG 11 42 12.253 +00 20 03.68   14.16 13.67 13.41 13.03 eS/lS 178 0
41 LEDA 37102 Sy1 11 51 33.3537570144 -02 22 21.893502576   17       ~ 161 0
42 LEDA 2815986 G 12 02 02.4750603336 +54 15 51.049196784   18.0       ~ 70 0
43 LEDA 39055 EmG 12 14 02.4588226248 +53 45 17.525587212   18       ~ 77 0
44 NGC 4228 SBG 12 15 39.174 +36 19 36.80 10.63 10.30 9.93 9.74   ~ 942 1
45 LEDA 39402 H2G 12 17 17.093 -28 02 32.67   17       ~ 134 0
46 LEDA 101471 EmG 12 24 36.7369432538 +37 24 35.833921444           ~ 33 0
47 Mrk 209 bCG 12 26 16.02 +48 29 36.6   15.3       ~ 334 0
48 NGC 4449 EmG 12 28 11.118 +44 05 36.81 10.11 9.98 9.64 9.45   ~ 1104 1
49 2MASX J12390403+3920437 H2G 12 39 04.0340323080 +39 20 43.370050560   18.7       ~ 25 0
50 LEDA 2790846 EmG 12 51 52.4 +49 03 25   18.0       ~ 52 0
51 NGC 4861 H2G 12 59 02.340 +34 51 33.98   12.90 12.32     ~ 375 2
52 LEDA 101484 EmG 13 06 24.193 +35 13 43.00           ~ 37 0
53 LEDA 169741 H2G 13 21 19.6991553744 +32 08 24.832025232   19.123       ~ 26 0
54 LEDA 46982 bCG 13 25 48.60 -11 36 38.0           ~ 82 0
55 LEDA 101493 EmG 13 33 08.394 +36 36 32.45   16.7       ~ 27 0
56 NGC 5253 AGN 13 39 55.990 -31 38 24.11 11.48 10.94 10.49 10.33 13.47 ~ 1345 4
57 MCG+07-29-060 QSO 14 17 01.716 +43 30 13.52   15.6       ~ 167 0
58 UGC 9497 H2G 14 44 12.8032800372 +42 37 43.773570223   16.0       ~ 76 0
59 NVSS J153412+571655 rG 15 34 13.3862564640 +57 17 07.282532472   15.8       ~ 72 1
60 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1536 0
61 Mrk 930 AGN 23 31 58.630 +28 56 50.51 14.27 15.04 14.63 14.56 14.46 ~ 135 0
62 AGC 332347 bCG 23 54 56.7 +27 49 59           ~ 17 0
63 NAME Local Group GrG ~ ~           ~ 8149 0

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2023.09.26-00:17:31

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