2016ApJ...825...44I


Query : 2016ApJ...825...44I

2016ApJ...825...44I - Astrophys. J., 825, 44-44 (2016/July-1)

ALMA investigation of vibrationally excited HCN/HCO+/HNC emission lines in the AGN-Hosting ultraluminous infrared galaxy IRAS 20551-4250.

IMANISHI M., NAKANISHI K. and IZUMI T.

Abstract (from CDS):

We present the results of ALMA Cycle 2 observations of the ultraluminous infrared galaxy IRAS 20551-4250 at HCN/HCO+/HNC J=3-2 lines at both vibrational ground (v=0) and vibrationally excited (v2=1) levels. This galaxy contains a luminous buried active galactic nucleus (AGN), in addition to starburst activity, and our ALMA Cycle 0 data revealed a tentatively detected vibrationally excited HCN v2=1f J=4-3 emission line. In our ALMA Cycle 2 data, the HCN/HCO+/HNC J=3-2 emission lines at v=0 are clearly detected. The HCN and HNC v2=1f J=3-2 emission lines are also detected, but the HCO+ v2=1f J=3-2 emission line is not. Given the high energy level of v2=1 and the resulting difficulty of collisional excitation, we compared these results with those of the calculation of infrared radiative pumping, using the available infrared 5-35 µm spectrum. We found that all of the observational results were reproduced if the HCN abundance was significantly higher than that of HCO+ and HNC. The flux ratio and excitation temperature between v2=1f and v=0, after correction for possible line opacity, suggests that infrared radiative pumping affects rotational (J-level) excitation at v=0 at least for HCN and HNC. The HCN-to-HCO+ v=0 flux ratio is higher than those of starburst-dominated regions, and will increase even more when the derived high HCN opacity is corrected. The enhanced HCN-to-HCO+ flux ratio in this AGN-hosting galaxy can be explained by the high HCN-to-HCO+ abundance ratio and sufficient HCN excitation at up to J=4, rather than the significantly higher efficiency of infrared radiative pumping for HCN than HCO+.

Abstract Copyright: © 2016. The American Astronomical Society. All rights reserved.

Journal keyword(s): galaxies: active - galaxies: nuclei - galaxies: Seyfert - galaxies: starburst - quasars: general - submillimeter: galaxies

Simbad objects: 13

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Number of rows : 13
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 NGC 1614 AGN 04 34 00.027 -08 34 44.57   14.66 13.99     ~ 620 0
2 NAME Ori A MoC 05 38 -07.1           ~ 2774 0
3 NGC 4355 Sy2 12 26 54.628 -00 52 39.51   14.21 13.37     ~ 431 2
4 Mrk 231 Sy1 12 56 14.2340989340 +56 52 25.238555193   14.68 13.84     ~ 1843 3
5 IC 860 LIN 13 15 03.51 +24 37 07.8   14.8       ~ 188 0
6 Z 49-57 GiC 15 13 13.1 +07 13 32   15.5       ~ 216 1
7 APG 220A PoG 15 34 57.22 +23 30 11.4           ~ 47 1
8 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2758 4
9 6dFGS gJ172322.0-001701 LIN 17 23 21.943 -00 17 00.96   15.1       ~ 381 0
10 W 49a SFR 19 10 15.7 +09 06 05           ~ 267 2
11 QSO B2052-474 QSO 20 56 16.35981874 -47 14 47.6276461   18.29 19.1 18.07   ~ 278 1
12 ESO 286-19 LIN 20 58 26.8182983654 -42 38 59.418569678   14.79 14.79 14.20   ~ 256 0
13 NAME South America H2G 22 51 49.307 -17 52 23.96   16.97       ~ 295 3

    Equat.    Gal    SGal    Ecl

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2021.07.26-05:33:19

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