2008A&A...489L..21B


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.10CET15:06:55

2008A&A...489L..21B - Astronomy and Astrophysics, volume 489, L21-24 (2008/10-2)

The magnetic field and the location of the TeV emitter in Cygnus X-1 and LS 5039.

BOSCH-RAMON V., KHANGULYAN D. and AHARONIAN F.A.

Abstract (from CDS):

Cygnus X-1 and LS 5039 are two X-ray binaries observed at TeV energies. Both sources are compact systems, contain jet-like (radio) structures, and harbor very luminous O stars. A TeV signal has been found around the superior conjunction of the compact object in both objects, when the highest gamma-ray opacities are expected. We investigate the implications of finding TeV emission from Cygnus X-1 and LS 5039 around the superior conjunction, since this can give information on the system magnetic field and the location of the TeV emitter. Using the very high-energy spectra and fluxes observed around the superior conjunction in Cygnus X-1 and LS 5039, we compute the absorbed luminosity that is caused by pair creation in the stellar photon field for different emitter positions with respect to the star and the observer line of sight. The role of the magnetic field and electromagnetic cascading are discussed. For the case of inefficient electromagnetic cascading, the expected secondary synchrotron fluxes are compared with the observed ones at X-ray energies. We find that, in Cygnus X-1 and LS 5039, either the magnetic field in the star surroundings is much smaller than the one expected for O stars or the TeV emitter is located at a distance >1012cm from the compact object. Our results strongly suggest that the TeV emitters in Cygnus X-1 and LS 5039 are located at the borders of the binary system and well above the orbital plane. This would not agree with those models for which the emitter is well inside the system, like the innermost-jet region (Cygnus X-1 and LS 5039; microquasar scenario) or the region between the pulsar and the primary star (LS 5039; standard pulsar scenario).

Abstract Copyright:

Journal keyword(s): gamma rays: theory - X-rays: binaries - radiation mechanisms: non-thermal

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 * tet01 Ori C ** 05 35 16.46375 -05 23 22.8486 4.20 5.15 5.13 4.91 4.73 O7Vp 1257 1
2 HD 36879 * 05 35 40.5264637356 +21 24 11.723003025 6.97 7.69 7.58     O7V(n)((f))z 131 0
3 * zet Ori A ** 05 40 45.527 -01 56 33.26 0.50 1.77 1.88 1.84 2.04 O9.2IbvarNwk 641 0
4 HD 148937 SB* 16 33 52.3867163783 -48 06 40.476619334 6.49 7.12 6.71 7.61   O6f?p 349 4
5 HD 152408 s*b 16 54 58.50567 -41 09 03.0964 5.17 5.92 5.77 7.00   O8Iape 345 0
6 * 9 Sgr Em* 18 03 52.4455370104 -24 21 38.639393923 5.08 5.97 5.97 5.72 5.70 O4V((f))z 511 0
7 V* V479 Sct HXB 18 26 15.0561532140 -14 50 54.249464136 12.02 12.23 11.27 11.04   ON6V((f))z 484 2
8 HD 226868 HXB 19 58 21.6758193269 +35 12 05.782512305 9.38 9.72 8.91 8.42   O9.7Iabpvar 3851 0
9 HD 191612 SB* 20 09 28.6111448914 +35 44 01.287772714 7.40 8.07 7.80     O8fpe 208 0

    Equat.    Gal    SGal    Ecl

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2019.12.10-15:06:55

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