Decomposition of a cosmic gamma-ray burst into two non-correlated radiation components

Chernenko, A.; Mitrofanov, I.

doi:10.1093/mnras/274.2.361

Cited by 7 publications

(7 citation statements)

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“…Since the region where the gamma-rays are produced is larger and has a smaller magnetic field than in models where the gamma-rays are produced at the polar cap, there is not sufficient pair production to truncate the spectrum at 1 MeV. A recent report by Chernenko and Mitrofanov (1995) of evidence for two components in the spectrum of GB881024 is intriguing. The soft component dominates the spectrum for E < 250 keV; the hard component is dominant at higher energies.…”

Section: Discussionmentioning

confidence: 97%

“…Since the region where the gamma-rays are produced is larger and has a smaller magnetic field than in models where the gamma-rays are produced at the polar cap, there is not sufficient pair production to truncate the spectrum at 1 MeV. A recent report by Chernenko and Mitrofanov (1995) The cyclotron line interpretation of the observed spectral features strongly supports a galactic origin for at least some gamma-ray bursts. Recent reports of fading x-ray and optical counterparts apparently associated with GB970228 raise hopes that we will soon know the distance scale to the burst sources.…”

Section: Fenimorementioning

confidence: 91%

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Cyclotron Line Formation in a Radiation‐driven Outflow

Isenberg¹,

Lamb²,

Wang³

1998

ApJ

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We calculate the properties of gamma-ray burst spectral lines formed by resonant cyclotron scattering in a radiation-driven outflow. Most previous models of line formation in gamma-ray bursts are appropriate at the polar cap of a neutron star located no further than several hundred parsecs away.However, the BATSE brightness and sky distributions indicate that, if bursters are galactic, they are located in a corona at distances greater than 100 kpc.At these distances the burst luminosity exceeds the Eddington luminosity and the plasma in a polar line-forming region is ejected along the field lines. The variation of the magnetic field strength and plasma velocity with altitude in such an outflow would seem to prevent the formation of narrow features like those observed by Ginga and other instruments. However, this is not the case because the majority of scatters occur close to the stellar surface, at altitudes below z ≈ r h , where r h ∼ 10 5 cm is the size of the photon source. Consequently, the interpretation of the observed features as cyclotron lines does not rule out burst sources in a galactic corona.The outflow model predicts both absorption-like and single-peaked emissionlike features. The latter do not occur in models with static line-forming regions, but have been observed in gamma-ray bursts by the Konus and BATSE instruments.

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Section: Discussionmentioning

confidence: 97%

“…Since the region where the gamma-rays are produced is larger and has a smaller magnetic field than in models where the gamma-rays are produced at the polar cap, there is not sufficient pair production to truncate the spectrum at 1 MeV. A recent report by Chernenko and Mitrofanov (1995) The cyclotron line interpretation of the observed spectral features strongly supports a galactic origin for at least some gamma-ray bursts. Recent reports of fading x-ray and optical counterparts apparently associated with GB970228 raise hopes that we will soon know the distance scale to the burst sources.…”

Section: Fenimorementioning

confidence: 91%

Cyclotron Line Formation in a Radiation‐driven Outflow

Isenberg¹,

Lamb²,

Wang³

1998

ApJ

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“…If so, the cross section for the two photon process is further reduced by the bulk motion of the pairs. A recent report by Chernenko and Mitrofanov (1995) of evidence for two components in the spectrum of GB881024 is intriguing. The soft component dominates the spectrum for E < 250 keV; the hard component is dominant above this energy.…”

Section: Gamma-ray Burstersmentioning

confidence: 97%

Effects of the Geometry of the Line‐forming Region on the Properties of Cyclotron Resonant Scattering Lines

Isenberg

Lamb

Wang

1998

ApJ

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We use a Monte Carlo radiative transfer code to examine the dependence of the properties of cyclotron resonant scattering lines on the spatial geometry and the optical depth of the line-forming region. We focus most of our attention on a line-forming region that is a plane-parallel slab. We also consider a cylindrical line-forming region. In both cases, the line-forming region contains an electron-proton plasma at the equilibrium Compton temperature, T c , and is threaded with a uniform magnetic field with strength ∼ 10 12 gauss. We consider geometries in which the photon source illuminates the line-forming region from below, and in which the photon source is embedded in the line-forming region.The former may correspond to a line-forming region in the magnetosphere of a neutron star, illuminated from below; the latter to a line-forming region on or near the surface of a neutron star as in an accretion column.In the case of the plane-parallel slab line-forming region, we study the behavior of the resonant Compton temperature and the properties of the cyclotron scattering lines as a function of the column depth of the line-forming region and the orientation of the magnetic field. At small or moderate optical depths (N e ≪ 10 25 cm −2 [electron scattering optical depth τ T o ≪ 10]), the resonant Compton temperature ranges from T e /E B ≈ 0.2 when the magnetic field is perpendicular to the slab to T e /E B ≈ 0.4 when the field is parallel to the slab. At large optical depths (N e ∼ > 1.5 × 10 25 cm −2 [τ T o ∼ > 10]), the resonant Compton temperature is higher.At small or moderate optical depths (τ T o ≪ 10), the equivalent widths, W E , of the spectral lines depend on two effects. First, W E increases as the viewing angle with respect to the field decreases, due to Doppler broadening.Second, W E increases as the viewing angle with respect to the slab normal

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“…Owing to statistical uncertainties and inhomogeneities of current GRB samples, available data on possible scalings of bright and dim GRB durations, fluxes, and spectra fail to provide an unambiguous distinction between the cosmological and local (the Galactic) origin of GRBs. Some statistical investigations of different GRB distributions give support to cosmological location of GRBs (Norris et al 1994;Wijers & Paczyński 1994;Kolatt & Piran 1996), whereas others favor the local one (Gurevich et al 1993;Hakkila et al 1995;Chernenko & Mitrofanov 1995;Mitrofanov et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Gamma‐Ray Bursts from Evolved Galactic Nuclei

Dokuchaev¹,

Eroshenko²,

Ozernoy³

1998

ApJ

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A new cosmological scenario for the origin of gamma ray bursts (GRBs) is proposed. In our scenario, a highly evolved central core in the dense galactic nucleus is formed containing a subsystem of compact stellar remnants (CSRs), such as neutron stars and black holes. Those subsystems result from the dynamical evolution of dense central stellar clusters in the galactic nuclei through merging of stars, thereby forming (as has been realized by many authors) the short-living massive stars and then CSRs. We estimate the rate of random CSR collisions in the evolved galactic nuclei by taking into account, similar to Quinlan & Shapiro (1987), the dissipative encounters of CSRs, mainly due to radiative losses of gravitational waves, which results in the formation of intermediate short-living binaries, with further coalescence of the companions to produce GRBs. We also consider how the possible presence of a central supermassive black hole, formed in a highly evolved galactic nucleus, influences the CSR binary formation. This scenario does not postulate ad hoc a required number of tight binary neutron stars in the galaxies. Instead, it gives, for the most realistic parameters of the evolved nuclei, the expected rate of GRBs consistent with the observed one, thereby explaining the GRB appearance in a natural way of the dynamical evolution of galactic nuclei. In addition, this scenario provides an opportunity for a cosmological GRB recurrence, previously considered to be a distinctive feature of GRBs of a local origin only. We also discuss some other observational tests of the proposed scenario.

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Decomposition of a cosmic gamma-ray burst into two non-correlated radiation components

Cited by 7 publications

References 0 publications

Cyclotron Line Formation in a Radiation‐driven Outflow

Cyclotron Line Formation in a Radiation‐driven Outflow

Effects of the Geometry of the Line‐forming Region on the Properties of Cyclotron Resonant Scattering Lines

Gamma‐Ray Bursts from Evolved Galactic Nuclei

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