Issue |
A&A
Volume 450, Number 1, April IV 2006
|
|
---|---|---|
Page(s) | 117 - 128 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20054297 | |
Published online | 03 April 2006 |
X-ray luminosity function of faint point sources in the Milky Way
1
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85740 Garching bei München, Germany e-mail: sazonov@mpa-garching.mpg.de
2
Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117997 Moscow, Russia
Received:
3
October
2005
Accepted:
15
December
2005
We assessed the contribution to the X-ray (above 2 keV) luminosity
of the Milky Way by different classes of low-mass binary systems and
single stars. We began by using the RXTE Slew Survey of the sky at
to construct an X-ray luminosity function (XLF) of
nearby X-ray sources in the range
(where Lx is the
luminosity over 2–10 keV), occupied by coronally active binaries
(ABs) and cataclysmic variables (CVs). We then extended this XLF down to
using the Rosat All-Sky
Survey in soft X-rays and available information on the 0.1–10 keV
spectra of typical sources. We found that the local cumulative X-ray
(2–10 keV) emissivities (per unit stellar mass) of ABs and CVs are
1027 and
1027 erg s-1
, respectively. In addition to ABs and CVs representing old stellar populations, young stars locally emit
1027 erg s
. Finally to the XLF
of ABs and CVs we attached a high luminosity branch (up to ~1039 erg s-1) composed of neutron-star and black-hole low-mass X-ray binaries (LMXBs), derived in previous work. The
combined XLF covers ~12 orders of magnitude in luminosity. The
estimated combined contribution of ABs and CVs to the 2–10 keV
luminosity of the Milky Way is ~2
1038 erg s-1,
or ~3% of the integral luminosity of LMXBs averaged over nearby
galaxies. The XLF obtained in this work is used elsewhere to assess
the contribution of point sources to the Galactic ridge X-ray emission.
Key words: stars: luminosity function, mass function / Galaxy: structure / X-rays: binaries / X-rays: galaxies / X-rays: stars
© 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.