2012A&A...541A...4G


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.14CET06:08:43

2012A&A...541A...4G - Astronomy and Astrophysics, volume 541A, 4-4 (2012/5-1)

Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O, H218O, OH, 18OH, OI, HCN, and NH3.

GONZALEZ-ALFONSO E., FISCHER J., GRACIA-CARPIO J., STURM E., HAILEY-DUNSHEATH S., LUTZ D., POGLITSCH A., CONTURSI A., FEUCHTGRUBER H., VEILLEUX S., SPOON H.W.W., VERMA A., CHRISTOPHER N., DAVIES R., STERNBERG A., GENZEL R. and TACCONI L.

Abstract (from CDS):

Full range Herschel/PACS spectroscopy of the (ultra)luminous infrared galaxies NGC 4418 and Arp 220, observed as part of the SHINING key programme, reveals high excitation in H2O, OH, HCN, and NH3. In NGC 4418, absorption lines were detected with Elower>800K (H2O), 600K (OH), 1075K (HCN), and 600K (NH3), while in Arp 220 the excitation is somewhat lower. While outflow signatures in moderate excitation lines are seen in Arp 220 as have been seen in previous studies, in NGC 4418 the lines tracing its outer regions are redshifted relative to the nucleus, suggesting an inflow with {dot}(M)≲12M/yr. Both galaxies have compact and warm (Tdust>100K) nuclear continuum components, together with a more extended and colder component that is much more prominent and massive in Arp 220. A chemical dichotomy is found in both sources: on the one hand, the nuclear regions have high H2O abundances, ∼10–5, and high HCN/H2O and HCN/NH3 column density ratios of 0.1-0.4 and 2-5, respectively, indicating a chemistry typical of evolved hot cores where grain mantle evaporation has occurred. On the other hand, the high OH abundance, with OH/H2O ratios of ∼0.5, indicates the effects of X-rays and/or cosmic rays. The nuclear media have high surface brightnesses (>1013L/kpc2) and are estimated to be very thick (NH>1025cm–2). While NGC 4418 shows weak absorption in H218O and 18OH, with a 16O-to-18O ratio of > 250-500, the relatively strong absorption of the rare isotopologues in Arp 220 indicates 18O enhancement, with 16O-to-18O of 70-130. Further away from the nuclear regions, the H2O abundance decreases to ≲10–7 and the OH/H2O ratio is reversed relative to the nuclear region to 2.5-10. Despite the different scales and morphologies of NGC 4418, Arp 220, and Mrk 231, preliminary evidence is found for an evolutionary sequence from infall, hot-core like chemistry, and solar oxygen isotope ratio to high velocity outflow, disruption of the hot core chemistry and cumulative high mass stellar processing of 18O.

Abstract Copyright:

Journal keyword(s): galaxies: ISM - line: formation - ISM: kinematics and dynamics - infrared: galaxies - submillimeter: galaxies

Simbad objects: 11

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Number of rows : 11

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 ~ 2862 2
2 NAME W3 IRS 5 Y*O 02 25 40.54 +62 05 51.4           B1 322 0
3 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 1945 1
4 NAME Orion Core ? 05 35 14.5 -05 22 30           ~ 171 0
5 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 691 0
6 NGC 4355 Sy2 12 26 54.628 -00 52 39.51   14.21 13.37     ~ 387 2
7 MCG+00-32-013 GiP 12 27 04.526 -00 54 21.14   15.0   14.401   ~ 28 0
8 Mrk 231 Sy1 12 56 14.2340989340 +56 52 25.238555193   14.68 13.84     ~ 1738 3
9 NGC 5253 AGN 13 39 55.990 -31 38 24.11 11.48 10.94 10.49 10.33   ~ 1246 4
10 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2624 4
11 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1856 1

    Equat.    Gal    SGal    Ecl

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2019.11.14-06:08:43

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