Query : 2010A&A...514A..61B

2010A&A...514A..61B - Astronomy and Astrophysics, volume 514, A61-61 (2010/5-1)

Optical depths for gamma-rays in the radiation field of a star heated by an external X-ray source in LMXBs. Application to Hercules X-1 and Scorpius X-1.


Abstract (from CDS):

The surface of a low mass star inside a compact low mass X-ray binary system (LMXB) can be heated by an external X-ray source apparently caused by the accretion of mass onto a companion compact object (a neutron star or a black hole). As a result, the surface temperature of the star can become significantly higher than it is in the normal state resulting from thermonuclear burning. We investigate whether high energy electrons and gamma-rays, injected within the binary system, can efficiently interact with this enhanced radiation field. To decide this, we calculate the optical depths of the gamma-ray photons in the radiation field of such an irradiated star as a function of the phase of the binary system. Based on these calculations, we conclude that compact low mass X-ray binary systems may also become sources of high energy gamma-rays since conditions for the interaction of electrons and γ-rays are quite similar to those found within high mass TeV γ-ray binaries such as LS 5039 and LSI 303 +61. However, because of differences in the soft radiation field, the expected γ-ray light curves can differ significantly between low mass and high mass X-ray binaries. As an example, we apply these calculations to two well known LMXBs Her X-1 and Sco X-1. It is concluded that electrons accelerated to high energies inside these binaries should collide with a sufficient number of soft photon targets from the companion star to achieve efficient γ-ray production.

Abstract Copyright:

Journal keyword(s): binaries: close - gamma rays: general - radiation mechanisms: non-thermal

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 LS I +61 303 HXB 02 40 31.6644419688 +61 13 45.593918580 11.27 11.61 10.75 10.19 9.55 B0Ve 801 2
2 V* V818 Sco LXB 16 19 55.0692669024 -15 38 25.017666540 11.60 12.40 11.1     Oev 1570 0
3 V* HZ Her LXB 16 57 49.8110126616 +35 20 32.486555472 11.90 14.89 13.63 13.88   B3/6ep 1988 0
4 V* V479 Sct HXB 18 26 15.0561548880 -14 50 54.247274304 12.02 12.23 11.27 11.04   ON6V((f))z 530 2
5 SS 433 HXB 19 11 49.5647697480 +04 58 57.827127648   16.3 13.0     A7Ib: 2012 4
6 V* V1521 Cyg HXB 20 32 25.78 +40 57 27.9           WN4/5-6/7 1857 2

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