Status Report

The X-ray-faint Emission of the Supermassive Nuclear Black Hole of IC1459

By SpaceRef Editor
January 16, 2003
Filed under , ,

Astrophysics, abstract

From: Martin Elvis <>
Date: Wed, 15 Jan 2003 17:26:25 GMT (102kb)

The X-ray-faint Emission of the Supermassive Nuclear Black Hole of

G. Fabbiano (1),
M. Elvis (1),
S. Markoff (2),
A. Siemiginowska (1),
S. Pellegrini (3),
A. Zezas (1),
F. Nicastro (1),
G. Trinchieri (4),
J. McDowell (1) ((1) Harvard-Smithsonian Center for Astrophysics, (2) Center for Space Research, MIT, (3) Universita’ di Bologna, Italy, (4) Osservatorio di Brera, Milano, Italy)

Comments: 33 pages including 7 figures (1 full color, 2 with colored lines) and
5 tables. Astrophysical Journal, in press

Chandra observations of the supermassive black hole in the nucleus of IC1459
show a weak [L_X=8×10(40)erg s(-1), 0.3-8keV], unabsorbed nuclear X-ray source,
with a slope Gamma=1.88+/-0.09, and no strong Fe-K line at 6.4keV (EW$<382 eV).
This describes a normal AGN X-ray spectrum, but lies at 3×10(-7) below the
Eddington limit. The SED of the IC1459 nucleus is extremely radio loud compared
to normal radio-loud quasars. The nucleus is surrounded by hot ISM (kT~0.5-0.6
keV) with an average density of 0.3cm(-3), within the central ~180 pc radius,
which is comparable to the gravitational capture radius, r_A~140 pc. We
estimate that for a standard AGN efficiency of 10%, the Bondi accretion would
correspond to a luminosity of ~6×10(44)erg s(-1), nearly four orders of
magnitude higher than L_X. ADAF solutions can explain the X-ray spectrum, but
not the high radio/X-ray ratio. A jet model fits the radio-100micron and X-ray
spectra well. The total power in this jet is ~10% of L(Bondi), implying that
accretion close to the Bondi rate is needed.

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