2010A&A...518L..43G


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.07CET03:55:53

2010A&A...518L..43G - Astronomy and Astrophysics, volume 518, L43-43 (2010/7-2)

Herschel observations of water vapour in Markarian 231.

GONZALEZ-ALFONSO E., FISCHER J., ISAAK K., RYKALA A., SAVINI G., SPAANS M., VAN DER WERF P., MEIJERINK R., ISRAEL F.P., LOENEN A.F., VLAHAKIS C., SMITH H.A., CHARMANDARIS V., AALTO S., HENKEL C., WEISS A., WALTER F., GREVE T.R., MARTIN-PINTADO J., NAYLOR D.A., SPINOGLIO L., VEILLEUX S., HARRIS A.I., ARMUS L., LORD S., MAZZARELLA J., XILOURIS E.M., SANDERS D.B., DASYRA K.M., WIEDNER M.C., KRAMER C., PAPADOPOULOS P.P., STACEY G.J., EVANS A.S. and GAO Y.

Abstract (from CDS):

The Ultra luminous infrared galaxy (ULIRG) Mrk231 reveals up to seven rotational lines of water (H2O) in emission, including a very high-lying (Eupper=640K) line detected at a 4σ level, within the Herschel/SPIRE wavelength range (190<λ(µm)<640), whereas PACS observations show one H2O line at 78µm in absorption, as found for other H2O lines previously detected by ISO. The absorption/emission dichotomy is caused by the pumping of the rotational levels by far-infrared radiation emitted by dust, and subsequent relaxation through lines at longer wavelengths, which allows us to estimate both the column density of H2O and the general characteristics of the underlying far-infrared continuum source. Radiative transfer models including excitation through both absorption of far-infrared radiation emitted by dust and collisions are used to calculate the equilibrium level populations of H2O and the corresponding line fluxes. The highest-lying H2O lines detected in emission, with levels at 300-640 K above the ground state, indicate that the source of far-infrared radiation responsible for the pumping is compact (radius=110-180pc) and warm (Tdust=85-95K), accounting for at least 45% of the bolometric luminosity. The high column density, N(H2O)∼5x1017cm–2, found in this nuclear component, is most probably the consequence of shocks/cosmic rays, an XDR chemistry, and/or an ``undepleted chemistry'' where grain mantles are evaporated. A more extended region, presumably the inner region of the 1-kpc disk observed in other molecular species, could contribute to the flux observed in low-lying H2O lines through dense hot cores, and/or shocks. The H2O 78µm line observed with PACS shows hints of a blue-shifted wing seen in absorption, possibly indicating the occurrence of H2O in the prominent outflow detected in OH (Fisher et al., 2010A&A...518L..41F). Additional PACS/HIFI observations of H2O lines are required to constrain the kinematics of the nuclear component, as well as the distribution of H2O relative to the warm dust.

Abstract Copyright:

Journal keyword(s): ISM: molecules - galaxies: ISM - galaxies: individual: Mrk 231 - line: formation - infrared: ISM - submillimeter: galaxies

Simbad objects: 3

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Number of rows : 3

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 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 743 0
2 Mrk 231 Sy1 12 56 14.2340989340 +56 52 25.238555193   14.68 13.84     ~ 1818 3
3 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1981 1

    Equat.    Gal    SGal    Ecl

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