Issue |
A&A
Volume 460, Number 1, December II 2006
|
|
---|---|---|
Page(s) | 45 - 57 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20054756 | |
Published online | 12 September 2006 |
X-ray nature of the LINER nuclear sources
1
Instituto de Astrofísica de Andalucía, CSIC, Apartado Postal 3004, 18080 Granada, Spain e-mail: omaira@iaa.es
2
Instituto de Astronomía, UNAM, Apartado Postal 70-264, 04510 México D.F., México
Received:
22
December
2005
Accepted:
17
May
2006
We report the results from a homogeneous analysis
of the X-ray (Chandra ACIS) data available for a sample of 51
LINER galaxies selected from the catalogue by Carrillo et al. (1999, Rev. Mex. Astron. Astrofis., 35, 187)
and representative of the population of bright LINER sources. The
nuclear X-ray morphology has been classified by their
nuclear compactness in the hard band (4.5–8.0 keV) into 2 categories: active galactic nuclei (AGN) candidates (with a clearly identified
unresolved nuclear source) and starburst (SB) candidates (without a
clear nuclear source). Sixty percent of the total sample are classified as
AGNs, with a median luminosity of , which is an order of magnitude higher than for SB-like nuclei.
The spectral fitting allows us to conclude that most
of the objects need a non-negligible power-law contribution. When no
spectral fitting can be performed (data with a low signal-to-noise
ratio), the color–color diagrams allow us to roughly estimate physical
parameters, such as column density, temperature of the thermal model, or
spectral index for a power-law, and therefore to better constrain the
origin of the X-ray emission. The X-ray morphology, the
spectra, and the color–color diagrams together allow us to
conclude that a high percentage of LINER galaxies, at least ≈60%, could host AGN nuclei, although contributions from high-mass
X-ray binaries or ultra-luminous X-ray sources cannot be ruled out for
some galaxies.
Key words: galaxies: nuclei / X-rays: galaxies / galaxies: active
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.