Issue |
A&A
Volume 431, Number 2, February IV 2005
|
|
---|---|---|
Page(s) | 597 - 614 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20041074 | |
Published online | 04 February 2005 |
High mass X-ray binaries in the LMC: Dependence on the stellar population age and the “propeller” effect
1
Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117997 Moscow, Russia e-mail: pav_sht@hea.iki.rssi.ru
2
Max-Planck-Institute für Astrophysik, Karl-Schwarzschild-Str. 1, 85740 Garching bei München, Germany
Received:
12
April
2004
Accepted:
18
October
2004
We study the population of compact X-ray sources in the Large Magellanic
Cloud using the archival data of the XMM-Newton observatory. The total
area of the survey is 3.8 square degrees with a limiting
sensitivity of ≈10-14 erg/s/cm2, corresponding to a
luminosity of ≈
erg/s at the LMC distance.
Out of ~460 point sources detected in the 2–8 keV energy band,
the vast majority are background CXB sources, observed
through the LMC. Based on the properties of the optical and near-infrared
counterparts of the detected sources we identified 9 likely HMXB
candidates and 19 sources, whose nature is uncertain, thus providing
lower and upper limits on the luminosity distribution of HMXBs
in the observed part of LMC.
When considered globally, the bright end of this distribution
is consistent within statistical and systematic uncertainties with
extrapolation of the universal luminosity function of HMXBs. However,
there seems to be fewer low luminosity sources,
,
than predicted. We consider the impact of the “propeller effect” on
the HMXB luminosity distribution and show that it can
qualitatively explain the observed deficit of low luminosity sources.
We found significant field-to-field variations in the number of
HMXBs across the LMC, which appear to be uncorrelated with the star
formation rates inferred by the FIR and
emission. We
suggest that these variations are caused by the dependence of the
HMXB number on the age of the underlying stellar
population. Using the existence of large coeval stellar aggregates in
the LMC, we constrain the number of HMXBs as a function of time
τ elapsed since the star formation event in the range of τ
from ~
Myr to ~
Myr.
Key words: X-rays: galaxies / X-rays: binaries / stars: neutron / galaxies: Magellanic Clouds
© ESO, 2005
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