The Variable Gamma-Ray Source 2CG 135+01

Tavani, M.; Kniffen, D. A.; Mattox, J. R.; Paredes, J. M.; Foster, Rosalind

doi:10.1086/311281

Cited by 73 publications

(82 citation statements)

References 24 publications

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“…Although there are no other objects of note (radio-loud active galactic nuclei, or pulsars) coinciding with the 3EG source (Hartman et al 1999), its positional uncertainty was not small enough to firmly associate the gamma-ray source with the binary. Variability in the EGRET light curve could be neither firmly established nor related to variability at other wavelengths (Tavani et al 1998;Nolan et al 2003). Recently, AGILE has reported detecting the source at the same flux level (Pittori et al 2009).…”

Section: Introductionmentioning

confidence: 98%

FERMI LAT OBSERVATIONS OF LS I +61°303: FIRST DETECTION OF AN ORBITAL MODULATION IN GeV GAMMA RAYS

Abdo¹,

Ackermann²,

Ajello³

et al. 2009

ApJ

136

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This Letter presents the first results from the observations of LS I +61 • 303 using Large Area Telescope data from the Fermi Gamma-Ray Space Telescope between 2008 August and 2009 March. Our results indicate variability that is consistent with the binary period, with the emission being modulated at 26.6 ± 0.5 days. This constitutes the first detection of orbital periodicity in high-energy gamma rays (20 MeV-100 GeV, HE). The light curve is characterized by a broad peak after periastron, as well as a smaller peak just before apastron. The spectrum is best represented by a power law with an exponential cutoff, yielding an overall flux above 100 MeV of 0.82 ± 0.03(stat) ± 0.07(syst) 10 −6 ph cm −2 s −1 , with a cutoff at 6.3 ± 1.1(stat) ± 0.4(syst) GeV and photon index Γ = 2.21 ± 0.04(stat) ± 0.06(syst). There is no significant spectral change with orbital phase. The phase of maximum emission, close to periastron, hints at inverse Compton scattering as the main radiation mechanism. However, previous very high-energy gamma ray (>100 GeV, VHE) observations by MAGIC and VERITAS show peak emission close to apastron. This and the energy cutoff seen with Fermi suggest that the link between HE and VHE gamma rays is nontrivial.

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Section: Introductionmentioning

confidence: 98%

FERMI LAT OBSERVATIONS OF LS I +61°303: FIRST DETECTION OF AN ORBITAL MODULATION IN GeV GAMMA RAYS

Abdo¹,

Ackermann²,

Ajello³

et al. 2009

ApJ

136

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“…A timing analysis carried out recently by Massi (2004) of pointed EGRET observations (Tavani et al 1998) (Fig. 6) This microquasar also seems to be a fast precessing system.…”

Section: Ls I +61 303 / 3eg J0241+6103mentioning

confidence: 83%

Microquasars as High-energy Gamma-ray Sources

Paredes

2005

Chin. J. Astron. Astrophys.

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Galactic microquasars are certainly one of the most recent additions to the field of high energy astrophysics and have attracted increasing interest over the last decade. However, the high energy part of the spectrum of microquasars is the most poorly known, mainly due the lack of sensitive instrumentation in the past. Microquasars are now primary targets for all of the observatories working in the X-ray and gamma-ray domains. They also appear as the possible counterparts for some of the unidentified sources of high-energy gamma-rays detected by the experiment EGRET on board the satellite COMPTON-GRO. This paper provides a general review of the main observational results obtained up to now as well as a summary of the scenarios for production of high-energy γ-rays at the present moment.

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“…The position is, on the contrary compatible with LS I +61 303 only 8 arcminutes away [19]. In 1998 Tavani and collaborators establish the possibility of variability of 2CG 135+01 on timescales of days [2]. Massi [5] examines the EGRET data as a function of the orbital phase and notices the clustering of high flux around the φ interval 0.2-0.5 estimated to be the periastron passage.…”

Section: Gamma-ray Emissionmentioning

confidence: 94%

The gamma-ray emitting microquasar LS I +61 303

Massi¹,

Ribó²,

Paredes³

et al. 2005

AIP Conference Proceedings

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Abstract. LS I +61 303 is one of the most studied X-ray binary systems because of its two peculiarities: On the one hand being the probable counterpart of the variable gamma ray source 2CG 135+01 [1, 2] and on the other hand being a periodic radio source [3]. The recent discovery of a radio emitting jet extending ca. 200 AU at both sides of a central core [4] in all evidence has shown the occurrence of accretion/ejection processes in this system. However, the radio outbursts do not occur at periastron passage, where the accretion is at its maximum, but several days later. In addition, when the gamma-ray emission of 2CG 135+01 is examined along the orbital phase of LS I +61 303 one sees that this emission seems to peak at periastron passage [5]. Here in detail we analyse the trend of the gamma-ray data versus orbital phase and discuss the delay between peaks at gamma-rays and in the radio band within the framework of a two-peak accretion/ejection model proposed by Taylor et al. [6] and further developed by Martí & Paredes [7].

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The Variable Gamma-Ray Source 2CG 135+01

Cited by 73 publications

References 24 publications

FERMI LAT OBSERVATIONS OF LS I +61°303: FIRST DETECTION OF AN ORBITAL MODULATION IN GeV GAMMA RAYS

FERMI LAT OBSERVATIONS OF LS I +61°303: FIRST DETECTION OF AN ORBITAL MODULATION IN GeV GAMMA RAYS

Microquasars as High-energy Gamma-ray Sources

The gamma-ray emitting microquasar LS I +61 303

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