STUDY OF THE SPECTRAL AND TEMPORAL CHARACTERISTICS OF X-RAY EMISSION OF THE GAMMA-RAY BINARY LS 5039 WITH<i>SUZAKU</i>

Takahashi, Tadayuki; Kishishita, Tetsuichi; Uchiyama, Y.; Tanaka, Takaaki; Yamaoka, K.; Khangulyan, D.; Aharonian, F.; Bosch‐Ramon, V.; Hinton, J. A.

doi:10.1088/0004-637x/697/1/592

Cited by 103 publications

(214 citation statements)

References 40 publications

Supporting

Mentioning

169

Contrasting

Unclassified

Order By: Relevance

“…This source, also shown in Fig. 1, is found at 5.22 from 1FGL J1227.9-4852 and at 4.12 from the XSS J1227 optical 2 The broad-band 0.2-100 keV fluxes of LS I+61 • 303, LS 5039 and Cyg X-3 are taken from Chernyakova et al (2009), Takahashi et al (2009 and Hjalmarsdotter et al (2009), respectively. 3 http://www.heasarc.gsfc.nasa.gov/W3Browse/all/radio.…”

Section: Discussionmentioning

confidence: 66%

The intriguing nature of the high-energy gamma ray source XSS J12270-4859

Martino¹,

Falanga²,

Bonnet‐Bidaud

et al. 2010

A&A

125

View full text Add to dashboard Cite

Context. The nature of the hard X-ray source XSS J12270-4859 is still unclear. It was claimed to be a possible magnetic cataclysmic variable of the Intermediate Polar type from its optical spectrum and a possible 860 s X-ray periodicity in RXTE data. However, recent observations do not support the latter variability, leaving this X-ray source still unclassified. Aims. To investigate its nature we present a broad-band X-ray and gamma ray study of this source based on a recent XMM-Newton observation and archival INTEGRAL and RXTE data. Using the Fermi/LAT 1-year point source catalogue, we tentatively associate XSS J12270-4859 with 1FGL J1227.9-4852, a source of high-energy gamma rays with emission up to 10 GeV. We further complement the study with UV photometry from XMM-Newton and ground-based optical and near-IR photometry. Methods. We have analysed both timing and spectral properties in the gamma rays, X-rays, UV and optical/near-IR bands of XSS J12270-4859. Results. The X-ray emission is highly variable, showing flares and intensity dips. The flares consist of flare-dip pairs. Flares are detected in both X-rays and the UV range, while the subsequent dips are present only in the X-ray band. Further aperiodic dipping behaviour is observed during X-ray quiescence, but not in the UV. The broad-band 0.2-100 keV X-ray/soft gamma ray spectrum is featureless and well described by a power law model with Γ = 1.7. The high-energy spectrum from 100 MeV to 10 GeV is represented by a power law index of 2.45. The luminosity ratio between 0.1-100 GeV and 0.2-100 keV is ∼0.8, indicating that the GeV emission is a significant component of the total energy output. Furthermore, the X-ray spectrum does not greatly change during flares, quiescence and the dips seen in quiescence. The X-ray spectrum however hardens during the post-flare dips, where a partial covering absorber is also required to fit the spectrum. Optical photometry acquired at different epochs reveals a period of 4.32 hr that could be ascribed to the binary orbital period. Near-IR, possibly ellipsoidal, variations are detected. Large amplitude variability on shorter (tens mins) timescales is found to be non-periodic. Conclusions. The observed variability at all wavelengths together with the spectral characteristics strongly favour a low-mass atypical low-luminosity X-ray binary and are against a magnetic cataclysmic variable nature. The association with a Fermi/LAT high-energy gamma ray source further strengths this interpretation.

show abstract

Section: Discussionmentioning

confidence: 66%

The intriguing nature of the high-energy gamma ray source XSS J12270-4859

Martino¹,

Falanga²,

Bonnet‐Bidaud

et al. 2010

A&A

125

View full text Add to dashboard Cite

show abstract

“…Takahashi et al (2009) argued that the X-ray spectrum necessarily implies dominant adiabatic cooling of an E −2 electron distribution (this is sufficient but not necessary: as discussed above, Klein-Nishina cooling also keeps the distribution hard). The X-ray and VHE observations were then be fitted by adjusting the adiabatic timescale t ad with orbital phase.…”

Section: Variations In Parameters?mentioning

confidence: 99%

“…There is no obvious reason why t ad should peak at this phase. Takahashi et al (2009) expect the variation in t ad to reflect variations in the size of the emitting zone, itself modulated by the external pressure of the wind. The relevant phases are those of apastron (low pressure) and periastron (high pressure), but not inferior conjunction which is an observerdependent phase unrelated to wind pressure.…”

Section: Variations In Parameters?mentioning

confidence: 99%

Relativistic Doppler-boosted emission in gamma-ray binaries

Dubus¹,

Cerutti²,

Henri³

2010

A&A

104

View full text Add to dashboard Cite

Context. Gamma-ray binaries could be compact pulsar wind nebulae formed when a young pulsar orbits a massive star. The pulsar wind is contained by the stellar wind of the O or Be companion, creating a relativistic comet-like structure accompanying the pulsar along its orbit. Aims. The X-ray and the very high energy (>100 GeV, VHE) gamma-ray emission from the binary LS 5039 are modulated on the orbital period of the system. Maximum and minimum flux occur at the conjunctions of the orbit, suggesting that the explanation is linked to the orbital geometry. The VHE modulation has been proposed to be due to the combined effect of Compton scattering and pair production on stellar photons, both of which depend on orbital phase. The X-ray modulation could be due to relativistic Doppler boosting in the comet tail where both the X-ray and VHE photons would be emitted. Methods. Relativistic aberrations change the seed stellar photon flux in the comoving frame so Doppler boosting affects synchrotron and inverse Compton emission differently. The dependence with orbital phase of relativistic Doppler-boosted (isotropic) synchrotron and (anisotropic) inverse Compton emission is calculated, assuming that the flow is oriented radially away from the star (LS 5039) or tangentially to the orbit (LS I +61 • 303, PSR B1259-63).Results. Doppler boosting of the synchrotron emission in LS 5039 produces a lightcurve whose shape corresponds to the X-ray modulation. The observations imply an outflow velocity of 0.15-0.33c consistent with the expected flow speed at the pulsar wind termination shock. In LS I +61 • 303, the calculated Doppler boosted emission peaks in phase with the observed VHE and X-ray maximum. Conclusions. Doppler boosting is not negligible in gamma-ray binaries, even for mildly relativistic speeds. The boosted modulation reproduces the X-ray modulation in LS 5039 and could also provide an explanation for the puzzling phasing of the VHE peak in LS I +61 • 303.

show abstract

“…at energies above 100 MeV by Fermi/LAT (Abdo et al, 2009;Hadasch et al, 2012), at hard X-rays (25 -200 keV) by INTEGRAL (Hoffmann et al, 2009) and at X-ray energies (1 -10 keV) by e.g. Suzaku (Takahashi et al, 2009). The microquasar is significantly detected at these energies, including the orbital modulation of its flux and energy spectrum.…”

Section: Introductionmentioning

confidence: 99%

LS 5039 – the counterpart of the unidentified MeV source GRO J1823-12

Collmar

Zhang

2014

A&A

View full text Add to dashboard Cite

Context. The COMPTEL experiment on CGRO observed the γ-ray sky at energies from 0.75 MeV to 30 MeV between April 1991 and June 2000. COMPTEL detected many γ-ray sources, among them an unidentified one labeled GRO J1823-12. It is located near l/b=17.5 • /-0.5 • and positionally consistent with the prominent γ-ray binary LS 5039. Aims. LS 5039 was established as a γ-ray source at TeV energies by HESS and at GeV energies by Fermi/LAT during recent years, whose γ-ray radiation is modulated along its binary orbit. Given this new information we reanalysed the COMPTEL data of GRO J1823-12 including an orbital resolved analysis. Methods. We applied the standard methods, proper event selections and data binning with subsequent maximum-likelihood deconvolution, to analyse the COMPTEL data. In addition we developed a tool to select and bin the COMPTEL data in a phase-resolved manner. We present the orbit-averaged as well as orbit-resolved MeV analyses, lightcurves and spectra, and put them into multifrequency context. Results. The COMPTEL data show a significant MeV source, which is positionally consistent with LS 5039, however also with other closeby Fermi/LAT sources. The orbit-resolved analysis provides strong evidence, at about the 3σ level, that the MeV flux of GRO J1823-12 is modulated along the binary orbit of about 3.9 days of LS 5039. We show that at MeV energies the source is brighter at the orbital part around the inferior conjuction than at the part of the superior conjunction, being in phase with X-rays and TeV γ-rays, however being in anti-phase with GeV γ-rays. The high-energy SED (X-rays to TeV γ-rays) shows the high-energy emission maximum of LS 5039 at MeV energies. Conclusions. We conclude that the COMPTEL source GRO J1823-12 is the counterpart of the microquasar LS 5039, at least for the majority of its MeV emission. The COMPTEL fluxes, put into multifrequency perspective, provide new constraints on the modelling of the high-energy emission pattern of the γ-ray binary LS 5039.

show abstract

STUDY OF THE SPECTRAL AND TEMPORAL CHARACTERISTICS OF X-RAY EMISSION OF THE GAMMA-RAY BINARY LS 5039 WITHSUZAKU

Cited by 103 publications

References 40 publications

The intriguing nature of the high-energy gamma ray source XSS J12270-4859

The intriguing nature of the high-energy gamma ray source XSS J12270-4859

Relativistic Doppler-boosted emission in gamma-ray binaries

LS 5039 – the counterpart of the unidentified MeV source GRO J1823-12

Contact Info

Product

Resources

About