C.D.S. - SIMBAD4 rel 1.7 - 2021.03.07CET04:35:11

2004A&A...420..905G - Astronomy and Astrophysics, volume 420, 905-910 (2004/6-4)

XMM-Newton observations of the dwarf elliptical galaxy NGC 3226.


Abstract (from CDS):

We report on an XMM-Newton observation of the dwarf elliptical galaxy NGC 3226 performed in November 2000. The analysis of the 0.4-10keV spectrum of its nucleus is consistent with a power law continuum (Γ≃1.96) absorbed at low energies by neutral gas (with a hydrogen column density NH≃3-8x1021cm–2 and a covering fraction greater than 85%) and by weakly ionized gas (NW≃4-6x1021cm–2 with ξ≃1-7(erg/s)*cm). However, the study indicates that a bremstrahlung model absorbed by neutral material is a better description reminiscent of the X-ray emission from advection-dominated accretion flows (ADAFs). The temperature of the best fit bremstrahlung model (T≃108K) and the absence of short and mid time-scale variability suggests that the X-ray emission originates from regions relatively far from the nucleus as in convection-dominated accretion flows (CDAFs) or in the so-called ``wind'' models. By comparing the 2-10keV luminosity of the central object (LX=2.58x1040erg/s after correction from Galactic and intrinsic absorption) with radio flux measurements, we find a mass in the range (1.7-50)x107M for the accreting black hole, a value comparable with an independent estimate from the dispersion of radial velocities. We argue that the dwarf elliptical galaxy NGC 3226 may harbor a sub-Eddington, super-massive black hole in a radiative inefficient state which is distinct from the near-Eddington, thermally dominated black holes presumably found in quasars and luminous Seyfert galaxies.

Abstract Copyright:

Journal keyword(s): X-rays: individual: NGC 3226 - galaxies: nuclei - galaxies: elliptical and lenticular, cD - X-rays: galaxies

Simbad objects: 4

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Number of rows : 4

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 CXOU J102326.7+195407 X 10 23 26.7 +19 54 07           ~ 4 0
2 NGC 3226 GiP 10 23 27.0067240562 +19 53 54.682329315   14.32 13.33     ~ 399 1
3 NGC 3227 GiP 10 23 30.57 +19 51 54.3   12.61 11.79     ~ 1566 2
4 CXOU J102334.1+195347 X 10 23 34.1 +19 53 47           ~ 3 0

    Equat.    Gal    SGal    Ecl

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