Detection of ultrahigh-energy radiation from Scorpius X-1: Ooty observations during 1984–1987

Tonwar, S. C.; Gopalakrishnan, N. V.; Gupta, S. K.; Rajeev, M. R.; Sreekantan, B. V.; Srivatsan, R.

doi:10.1103/physrevlett.67.2248

Cited by 7 publications

(5 citation statements)

References 7 publications

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“…Sco X-1 has been also claimed as a TeV-PeV γ-rays source in the 80-ties but with the low significance (e.g. Brazier et al 1990, Tonwar et al 1991. Also these results have not been confirmed by latter observations.…”

Section: Sco X-1mentioning

confidence: 91%

Optical depths for gamma-rays in the radiation field of a star heated by an external X-ray source in LMXBs

Bednarek

Pabich

2010

A&A

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The surface of a low mass star inside a compact low mass X-ray binary system (LMXB) can be heated by an external X-ray source apparently caused by the accretion of mass onto a companion compact object (a neutron star or a black hole). As a result, the surface temperature of the star can become significantly higher than it is in the normal state resulting from thermonuclear burning. We investigate whether high energy electrons and gamma-rays, injected within the binary system, can efficiently interact with this enhanced radiation field. To decide this, we calculate the optical depths of the gamma-ray photons in the radiation field of such an irradiated star as a function of the phase of the binary system. Based on these calculations, we conclude that compact low mass X-ray binary systems may also become sources of high energy gamma-rays since conditions for the interaction of electrons and γ-rays are quite similar to those found within high mass TeV γ-ray binaries such as LS 5039 and LSI 303 +61. However, because of differences in the soft radiation field, the expected γ-ray light curves can differ significantly between low mass and high mass X-ray binaries. As an example, we apply these calculations to two well known LMXBs Her X-1 and Sco X-1. It is concluded that electrons accelerated to high energies inside these binaries should collide with a sufficient number of soft photon targets from the companion star to achieve efficient γ-ray production.

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Section: Sco X-1mentioning

confidence: 91%

Optical depths for gamma-rays in the radiation field of a star heated by an external X-ray source in LMXBs

Bednarek

Pabich

2010

A&A

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“…[17] subsequently reported periodic emission from this object at energies -1017 eV. Finally, Tonwar et al [18] reported a burst of emission by Sco X-1 at energies -1014 eV. This observation was subsequently confirmed by Meyhandan et al [19].…”

Section: Introductionmentioning

confidence: 75%

“…J is from [36], WC from [37], 52 from this paper, B from [38], A from this paper, 0 1 and 0 2 from Ref. [18], A1 from [19], A2 from [14], and SU from [15].…”

Section: Measurement Of Uhe 7-ray Fluxes From Known Objectsmentioning

confidence: 99%

Search for point sources of ultrahigh energyγrays in the southern sky

et al. 1993

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“…Recent positive reports from long-running experiments include those of Rawat et al ( 1991 ) on Her X-l, Tonwar et al (1991) on Sco X-l, Tonwar et al (1992) on Cyg X-3, Meyhandan et al ( 1992) on LMC X-4, and Acharyu et al (1991) on the Crab. Because the detectors have rather poor angular resolution, evidence for source identification typically includes phasing with a previously known orbit or rotation period.…”

Section: Tev and Pev Sourcesmentioning

confidence: 99%

Astrophysics in 1992

Trimble

1993

PASP

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1992 was an astrophysically exciting year for most of us. E-mail lines buzzed with news of the COBE anisotropy, the Gallex solar-neutrino flux, a pulsar with two planets, and the remarkable isotropy of the gamma-ray burst sources seen by CGRO. Meanwhile, more routine work continued on problems like star formation that have been around for decades and seem unlikely to be fully resolved in this millenium. The overview of the year presented here attempts to strike some balance between the new discoveries and the less spectacular, but equally important, progress that comes from many people tackling a subject in different ways. Seven self-contained sections discuss the Sun, extra-solar-system planets, the search for brown dwarfs, triggered star formation, gamma-ray sources, the unified model of active galaxies, and large-scale lumpiness in the universe. Five sections of shorter items concern ( 1 ) the solar system and Milky Way, (2) discoveries of things long sought, (3) the converse, and (4) and ( 5) various kinds of corrections and updates.

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Detection of ultrahigh-energy radiation from Scorpius X-1: Ooty observations during 1984–1987

Cited by 7 publications

References 7 publications

Optical depths for gamma-rays in the radiation field of a star heated by an external X-ray source in LMXBs

Optical depths for gamma-rays in the radiation field of a star heated by an external X-ray source in LMXBs

Search for point sources of ultrahigh energyγrays in the southern sky

Astrophysics in 1992

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