2006A&A...460..743A


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.22CEST12:26:04

2006A&A...460..743A - Astronomy and Astrophysics, volume 460, 743-749 (2006/12-4)

3.9 day orbital modulation in the TeV γ-ray flux and spectrum from the X-ray binary LS 5039.

AHARONIAN F., AKHPERJANIAN A.G., BAZER-BACHI A.R., BEILICKE M., BENBOW W., BERGE D., BERNLOEHR K., BOISSON C., BOLZ O., BORREL V., BRAUN I., BROWN A.M., BUEHLER R., BUESCHING I., CARRIGAN S., CHADWICK P.M., CHOUNET L.-M., CORNILS R., COSTAMANTE L., DEGRANGE B., DICKINSON H.J., DJANNATI-ATAIE A., DRURY L.O'C., DUBUS G., EGBERTS K., EMMANOULOPOULOS D., ESPIGAT P., FEINSTEIN F., FERRERO E., FIASSON A., FONTAINE G., FUNK SEB., FUNK S., FUESSLING M., GALLANT Y.A., GIEBELS B., GLICENSTEIN J.F., GORET P., HADJICHRISTIDIS C., HAUSER D., HAUSER M., HEINZELMANN G., HENRI G., HERMANN G., HINTON J.A., HOFFMANN A., HOFMANN W., HOLLERAN M., HORNS D., JACHOLKOWSKA A., DE JAGER O.C., KENDZIORRA E., KHELIFI B., KOMIN N., KONOPELKO A., KOSACK K., LATHAM I.J., LE GALLOU R., LEMIERE A., LEMOINE-GOUMARD M., LOHSE T., MARTIN J.M., MARTINEAU-HUYNH O., MARCOWITH A., MASTERSON C., MAURIN G., McCOMB T.J.L., MOULIN E., DE NAUROIS M., NEDBAL D., NOLAN S.J., NOUTSOS A., ORFORD K.J., OSBORNE J.L., OUCHRIF M., PANTER M., PELLETIER G., PITA S., PUEHLHOFER G., PUNCH M., RAUBENHEIMER B.C., RAUE M., RAYNER S.M., REIMER A., REIMER O., RIPKEN J., ROB L., ROLLAND L., ROWELL G., SAHAKIAN V., SANTANGELO A., SAUGE L., SCHLENKER S., SCHLICKEISER R., SCHROEDER R., SCHWANKE U., SCHWARZBURG S., SHALCHI A., SOL H., SPANGLER D., SPANIER F., STEENKAMP R., STEGMANN C., SUPERINA G., TAVERNET J.-P., TERRIER R., TLUCZYKONT M., VAN ELDIK C., VASILEIADIS G., VENTER C., VINCENT P., VOELK H.J., WAGNER S.J. and WARD M.

Abstract (from CDS):

LS 5039 is a High Mass X-ray Binary (HMXRB) comprising a compact object in an eccentric 3.9day orbit around a massive O6.5V star. Observations at energies above 0.1TeV (1011eV) by the High Energy Stereoscopic System (HESS) in 2004 revealed that LS 5039 is a source of Very High Energy (VHE) γ-rays and hence, is able to accelerate particles to multi-TeV energies. Deeper observations by HESS were carried out in 2005 in an effort to probe further the high energy astrophysics taking place. In particular, we have searched for orbital modulation of the VHE γ-ray flux, which if detected, would yield new information about the complex variation in γ-ray absorption and production within X-ray binary systems. Observations at energies above 0.1TeV (1011eV), were carried out with the High Energy Stereoscopic System (HESS) of Cherenkov Telescopes in 2005. A timing analysis was performed on the dataset employing the Lomb-Scargle and Normalised Rayleigh statistics, and orbital phase-resolved energy spectra were obtained. The timing analysis reveals a highly significant (post-trial chance probability <10–15) peak in the TeV emission periodogram at a frequency matching that of the 3.9day orbital motion of the compact object around the massive stellar companion. This is the first time in γ-ray astronomy that orbital modulation has been observed, and periodicity clearly established using ground-based γ-ray detectors. The γ-ray emission is largely confined to half of the orbit, peaking around the inferior conjunction epoch of the compact object. Around this epoch, there is also a hardening of the energy spectrum in the energy range between 0.2TeV and a few TeV. The γ-ray flux vs. orbital phase profile suggests the presence of γ-ray absorption via pair production, which would imply that a large fraction of the γ-ray production region is situated within ∼1AU of the compact object. This source size constraint can be compared to the collimated outflows or jets observed in LS 5039 resolved down to scales of a few AU. The spectral hardening is however not explained exclusively by the absorption effect, indicating that other effects are present, perhaps related to the γ-ray production mechanism(s). If the γ-ray emission arises from accelerated electrons, the hardening may arise from variations with phase in the maximum electron energies, the dominant radiative mechanism, and/or the angular dependence in the inverse-Compton scattering cross-section. Overall, these results provide new insights into the competing γ-ray absorption and production processes in X-ray binaries.

Abstract Copyright:

Journal keyword(s): gamma rays: observations - acceleration of particles - block hole physics - stars: binaries: close

Simbad objects: 4

goto Full paper

goto View the reference in ADS

Number of rows : 4

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 LS I +61 303 HXB 02 40 31.6641883136 +61 13 45.591138110 11.27 11.61 10.75 10.19 9.55 B0Ve 749 2
2 PSR J1826-1256 Psr 18 26 08.570 -12 56 33.53           ~ 94 1
3 PSR B1823-13 Psr 18 26 13.06 -13 34 48.1           ~ 343 1
4 V* V479 Sct HXB 18 26 15.0561532140 -14 50 54.249464136 12.02 12.23 11.27 11.04   ON6V((f))z 483 2

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2006A&A...460..743A and select 'bookmark this link' or equivalent in the popup menu


2019.10.22-12:26:04

© Université de Strasbourg/CNRS

    • Contact