Query : 2001A&A...378..509J

2001A&A...378..509J - Astronomy and Astrophysics, volume 378, 509-521 (2001/11-1)

Neutron-capture and 2.22 MeV emission in the atmosphere of the secondary of an X-ray binary.


Abstract (from CDS):

We consider the production of 2.22MeV radiation resulting from the capture of neutrons in the atmosphere of the secondary in an X-ray binary system, where the neutrons are produced in the accretion disk around the compact primary star and radiated in all directions. We have considered several accretion disk models (ADAF, ADIOS, SLE, Uniform-Temperature) and a varity of parameters (accretion rate, mass of the compact object, mass, temperature and composition of the secondary star, distance between the two objects, etc.). The neutron rates are calculated by a network of nuclear reactions in the accretion disk, and this is handled by a reaction-rate formulation taking into account the structure equations given by each accretion model. The processes undergone by the neutrons in the atmosphere of the companion star are studied in great detail, including thermalization, elastic and inelastic scatterings, absorption, escape from the surface, decay, and capture by protons. The radiative transfer of the 2.22MeV photons is treated separately, taking into consideration the composition and density of the star's atmosphere. The final flux of the 2.22MeV radiation that can be detected from earth is calculated taking into account the distance to the source, the direction of observation with respect to the binary system frame, and the rotation of the source, as this can lead to an observable periodicity in the flux. We produce phasograms of the 2.22MeV intensity as well as spectra of the line, where rotational Doppler shift effects can lead to changes in the spectra that are measurable by INTEGRAL's spectrometer (SPI).

Abstract Copyright:

Journal keyword(s): X-rays: binaries - accretion, accretion disks - gamma-ray: theory - lines: profiles - nuclear reactions, nucleosynthesis, abundances

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 - 2024
1 V* GP Vel HXB 09 02 06.8608812864 -40 33 16.899168060 6.85 7.37 6.87 6.31 6.05 B0.5Ia 1487 0
2 V* HZ Her LXB 16 57 49.8110126616 +35 20 32.486555472 11.90 14.89 13.63 13.88   B3/6ep 2061 0
3 HD 226868 HXB 19 58 21.6757355952 +35 12 05.784512688 9.38 9.72 8.91 8.42   O9.7Iabpvar 4282 0
4 V* V1521 Cyg HXB 20 32 25.78 +40 57 27.9           WN4/5-6/7 1907 2

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