2016A&A...586A..89C


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.06CEST23:03:42

2016A&A...586A..89C - Astronomy and Astrophysics, volume 586A, 89-89 (2016/2-1)

Water masers in Compton-thick AGN. I. Detailed study of the new water megamaser in IRAS 15480-0344.

CASTANGIA P., TARCHI A., CACCIANIGA A., SEVERGNINI P. and DELLA CECA R.

Abstract (from CDS):

A relationship between the water maser detection rate and large nuclear column densities in AGN has often been cited in the literature. Indeed, detailed studies of luminous water masers, typically associated with the nuclear activity, allow us to investigate the innermost regions of AGN, with an impact on the still debated Unified Model for this class of objects. We have recently entertained a search for maser emission in a well-defined sample of Compton-thick AGN aimed at investigating, on firm statistical bases, the aforementioned relationship. While the survey is still ongoing, and is the subject of a forthcoming publication, a new luminous water maser has been detected in the lenticular (field) S0 galaxy IRAS 15480-0344, whose origin, associated with an accretion disc or a nuclear outflow/jet, needs to be assessed. Multi-epoch single-dish observations and VLBI measurements were performed to investigate the distribution, spatial extension, and variability of the maser emission in order to infer the main characteristics of the water megamaser. The new detection in IRAS 15480-0344 is reported: a megamaser with a total single-dish isotropic luminosity of ∼200L and a profile composed of two main features, a broad line with a full width to half maximum (FWHM) linewidth of ∼90km/s and a narrow (FWHM<1km/s) one. We performed a follow-up to the detection with the Very Long Baseline Array (VLBA) and confidently detected only the narrow component, which is coincident with the nuclear radio continuum emission detected with the Very Large Array at 8.4GHz. A weak narrow feature has also been detected in the velocity range of the broad feature and is located 15pc to the north-west with respect to the stronger component. Neither maser spot is associated with the compact radio continuum sources derived from the same VLBA dataset. The different line profiles and the spatial separation between the two features in the spectrum of IRAS 15480-0344 suggests a composite origin for the maser. The large linewidth and the strong spectral variability indicate that the broad component might originate from the interaction between a radio jet and ambient molecular clouds. Based on its small linewidth and the absence of high velocity features, instead, we favour an outflow origin for the narrow component. This scenario is consistent with the hypothesis of the presence of strong nuclear outflows recently invoked to explain the main characteristics of field S0 galaxies.

Abstract Copyright:

Journal keyword(s): masers - galaxies: active - galaxies: nuclei - galaxies: Seyfert - radio lines: galaxies - radio lines: ISM

Nomenclature: Table 3: [CTC2016] MN (Nos M1-M2). Table 4: [CTC2016] CN (Nos C1-C2).

Simbad objects: 18

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Number of rows : 18

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 SN 1986J SN* 02 22 31.33 +42 19 56.4   18.4 18.4     SNII 306 1
2 NGC 891 H2G 02 22 32.907 +42 20 53.95 11.08 10.81 9.93 7.86   ~ 1520 2
3 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 4089 2
4 NGC 1365 Sy1 03 33 36.458 -36 08 26.37 10.48 10.08 9.63 8.79 9.7 ~ 1523 2
5 ICRF J092703.0+390220 Sy1 09 27 03.0139516273 +39 02 20.847968628   17.17 17.00 16.486   ~ 932 1
6 NGC 3079 Sy2 10 01 57.80342 +55 40 47.2428 11.57 11.54 10.86     ~ 1247 3
7 M 106 Sy2 12 18 57.620 +47 18 13.39   9.14 8.41 8.11   ~ 2113 3
8 [CTC2016] M1 Mas 15 50 41.49695 -03 53 18.0217           ~ 1 0
9 [CTC2016] C2 Rad 15 50 41.49723 -03 53 18.0773           ~ 1 0
10 [CTC2016] C1 Rad 15 50 41.49736 -03 53 18.0572           ~ 1 0
11 [CTC2016] M2 Mas 15 50 41.49847 -03 53 18.0115           ~ 1 0
12 IRAS 15480-0344 Sy2 15 50 41.521 -03 53 17.58   16.20 15.1 14.83   ~ 81 0
13 [VV2006] J155530.8-032650 QSO 15 55 30.74815106 -03 26 49.5199764     20.7 19.9   ~ 21 1
14 QSO B1555+001 QSO 15 57 51.43397128 -00 01 50.4137075   20.10 19.72 18.75   ~ 164 1
15 3C 345 QSO 16 42 58.8100340220 +39 48 36.999540578   16.81 16.59 16.84   ~ 1552 2
16 7C 175844.60+384828.00 QSO 18 00 24.76536125 +38 48 30.6975330   17.8 17.8 17.04   ~ 130 1
17 W 49n HII 19 10 13.2 +09 06 12           ~ 411 3
18 IC 5063 Sy2 20 52 02.329 -57 04 07.60   12.92 13.60 11.30   ~ 543 1

    Equat.    Gal    SGal    Ecl

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2020.07.06-23:03:42

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