EDP Sciences
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Volume 368, Number 1, March II 2001
Page(s) 44 - 51
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20000522

A&A 368, 44-51 (2001)
DOI: 10.1051/0004-6361:20000522

An X-ray and near-IR spectroscopic analysis of the ULIRG IRAS 05189-2524

P. Severgnini1, G. Risaliti1, A. Marconi2, R. Maiolino2 and M. Salvati2

1  Dipartimento di Astronomia, Università di Firenze, L.go E. Fermi 5, 50125 Firenze, Italy
2  Osservatorio Astrofisico di Arcetri, L.go E. Fermi 5, 50125 Firenze, Italy

(Received 8 November 2000 / Accepted 19 December 2000 )

We present new, quasi-simultaneous hard X-ray and near-IR spectra of the ultraluminous infrared galaxy IRAS 05189-2524, and discuss them together with archival and literature data. The 1.9 Seyfert nucleus is Compton-thin. The near-IR broad lines are seen in transmission, similarly to the X-rays, and the medium along the line of sight has an $A_V/N_{\rm H}$ ratio definitely lower than Galactic. The increase in obscuration observed at the latter epoch has $\Delta A_V/ \Delta N_{\rm H}$ also less than Galactic, supporting a correlation between the properties of the obscuring matter and its proximity to the center. The measured AV is compatible with the broad component of $\rm H\alpha$ being seen in transmission, as opposed to scattering, so that most of the observed polarization must be due to dichroism. The bolometric luminosity of the AGN, deduced from the X-ray and line luminosities, falls definitely short of accounting for the IR luminosity of the galaxy, consistent with its coolish infrared color.

Key words: galaxies: Seyfert -- galaxies: starburst -- infrared: galaxies -- X -- rays: galaxies -- galaxies: individual: IRAS 05189-2524

Offprint request: P. Severgnini, paolas@arcetri.astro.it

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