Thermal synchrotron radiation and gamma-ray burst spectra

George Pavlov, S. V. Golenetskii

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The standard classical expressions for the thermal synchrotron (TS) radiation from an optically thin thermal plasma are shown to be inapplicable at photon energies E≳kT since they neglect quantum effects. Quantum relationships are obtained for the TS spectral emissivity, opacity, and polarization. The quantum TS spectra are much softer at E≳kT than the classical ones. The TS radiation exhibits strong linear polarization in the classical domain, whereas the quantum effects reduce the polarization at high E. Expressions for the classical TS luminosity are obtained with quantum corrections which turn out to be significant for (B/Bc)(kT/mc2)≳10-2(Bc=4.41×1013 G). Fitting the gamma-ray burst (GRB) spectra by the classical TS law (see, e.g., Liang et al., 1983) is incorrect in cases where kT is less than the maximum detected photon energy. The continua of the GRB spectra in the range E∼20 keV-2 MeV (Mazets et al., 1981a; Andreev et al., 1983) can be fitted satisfactorily by the quantum TS spectra. The results of this fitting may suggest the existence of temperatures much higher (up to ∼10 MeV), and of magnetic fields much lower (down to ∼109 G) than those usually accepted. Under these conditions the thickness of the TS sources (∼103-104 cm) could be comparable with their transverse dimensions (in contrast to sources with ordinary temperatures and fields), if they lie within a few kpc. The quantum TS spectra are too soft to account for the hard components (up to tens of MeV) of the GRB spectra detected by the Solar Maximum Mission (Nolan et al., 1984), unless the temperatures are unreasonably high. A straightforward TS interpretation of the GRB spectra seems to be unrealistic. Most probably, the continuum radiation escapes from an optically thick, strongly magnetized, highly non-stationary, hot plasma near the surface of a neutron star.

Original languageEnglish (US)
Pages (from-to)341-354
Number of pages14
JournalAstrophysics and Space Science
Volume128
Issue number2
DOIs
StatePublished - Dec 1 1986

Fingerprint

gamma ray bursts
synchrotron radiation
synchrotrons
polarization
plasma
Solar Maximum Mission
continuums
radiation
emissivity
thermal plasmas
photons
high temperature plasmas
opacity
linear polarization
energy
neutron stars
escape
temperature
magnetic field
luminosity

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Pavlov, George ; Golenetskii, S. V. / Thermal synchrotron radiation and gamma-ray burst spectra. In: Astrophysics and Space Science. 1986 ; Vol. 128, No. 2. pp. 341-354.
@article{d378dd6269d448d98ea5ee687091401c,
title = "Thermal synchrotron radiation and gamma-ray burst spectra",
abstract = "The standard classical expressions for the thermal synchrotron (TS) radiation from an optically thin thermal plasma are shown to be inapplicable at photon energies E≳kT since they neglect quantum effects. Quantum relationships are obtained for the TS spectral emissivity, opacity, and polarization. The quantum TS spectra are much softer at E≳kT than the classical ones. The TS radiation exhibits strong linear polarization in the classical domain, whereas the quantum effects reduce the polarization at high E. Expressions for the classical TS luminosity are obtained with quantum corrections which turn out to be significant for (B/Bc)(kT/mc2)≳10-2(Bc=4.41×1013 G). Fitting the gamma-ray burst (GRB) spectra by the classical TS law (see, e.g., Liang et al., 1983) is incorrect in cases where kT is less than the maximum detected photon energy. The continua of the GRB spectra in the range E∼20 keV-2 MeV (Mazets et al., 1981a; Andreev et al., 1983) can be fitted satisfactorily by the quantum TS spectra. The results of this fitting may suggest the existence of temperatures much higher (up to ∼10 MeV), and of magnetic fields much lower (down to ∼109 G) than those usually accepted. Under these conditions the thickness of the TS sources (∼103-104 cm) could be comparable with their transverse dimensions (in contrast to sources with ordinary temperatures and fields), if they lie within a few kpc. The quantum TS spectra are too soft to account for the hard components (up to tens of MeV) of the GRB spectra detected by the Solar Maximum Mission (Nolan et al., 1984), unless the temperatures are unreasonably high. A straightforward TS interpretation of the GRB spectra seems to be unrealistic. Most probably, the continuum radiation escapes from an optically thick, strongly magnetized, highly non-stationary, hot plasma near the surface of a neutron star.",
author = "George Pavlov and Golenetskii, {S. V.}",
year = "1986",
month = "12",
day = "1",
doi = "10.1007/BF00644582",
language = "English (US)",
volume = "128",
pages = "341--354",
journal = "Astrophysics and Space Science",
issn = "0004-640X",
publisher = "Springer Netherlands",
number = "2",

}

Thermal synchrotron radiation and gamma-ray burst spectra. / Pavlov, George; Golenetskii, S. V.

In: Astrophysics and Space Science, Vol. 128, No. 2, 01.12.1986, p. 341-354.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Thermal synchrotron radiation and gamma-ray burst spectra

AU - Pavlov, George

AU - Golenetskii, S. V.

PY - 1986/12/1

Y1 - 1986/12/1

N2 - The standard classical expressions for the thermal synchrotron (TS) radiation from an optically thin thermal plasma are shown to be inapplicable at photon energies E≳kT since they neglect quantum effects. Quantum relationships are obtained for the TS spectral emissivity, opacity, and polarization. The quantum TS spectra are much softer at E≳kT than the classical ones. The TS radiation exhibits strong linear polarization in the classical domain, whereas the quantum effects reduce the polarization at high E. Expressions for the classical TS luminosity are obtained with quantum corrections which turn out to be significant for (B/Bc)(kT/mc2)≳10-2(Bc=4.41×1013 G). Fitting the gamma-ray burst (GRB) spectra by the classical TS law (see, e.g., Liang et al., 1983) is incorrect in cases where kT is less than the maximum detected photon energy. The continua of the GRB spectra in the range E∼20 keV-2 MeV (Mazets et al., 1981a; Andreev et al., 1983) can be fitted satisfactorily by the quantum TS spectra. The results of this fitting may suggest the existence of temperatures much higher (up to ∼10 MeV), and of magnetic fields much lower (down to ∼109 G) than those usually accepted. Under these conditions the thickness of the TS sources (∼103-104 cm) could be comparable with their transverse dimensions (in contrast to sources with ordinary temperatures and fields), if they lie within a few kpc. The quantum TS spectra are too soft to account for the hard components (up to tens of MeV) of the GRB spectra detected by the Solar Maximum Mission (Nolan et al., 1984), unless the temperatures are unreasonably high. A straightforward TS interpretation of the GRB spectra seems to be unrealistic. Most probably, the continuum radiation escapes from an optically thick, strongly magnetized, highly non-stationary, hot plasma near the surface of a neutron star.

AB - The standard classical expressions for the thermal synchrotron (TS) radiation from an optically thin thermal plasma are shown to be inapplicable at photon energies E≳kT since they neglect quantum effects. Quantum relationships are obtained for the TS spectral emissivity, opacity, and polarization. The quantum TS spectra are much softer at E≳kT than the classical ones. The TS radiation exhibits strong linear polarization in the classical domain, whereas the quantum effects reduce the polarization at high E. Expressions for the classical TS luminosity are obtained with quantum corrections which turn out to be significant for (B/Bc)(kT/mc2)≳10-2(Bc=4.41×1013 G). Fitting the gamma-ray burst (GRB) spectra by the classical TS law (see, e.g., Liang et al., 1983) is incorrect in cases where kT is less than the maximum detected photon energy. The continua of the GRB spectra in the range E∼20 keV-2 MeV (Mazets et al., 1981a; Andreev et al., 1983) can be fitted satisfactorily by the quantum TS spectra. The results of this fitting may suggest the existence of temperatures much higher (up to ∼10 MeV), and of magnetic fields much lower (down to ∼109 G) than those usually accepted. Under these conditions the thickness of the TS sources (∼103-104 cm) could be comparable with their transverse dimensions (in contrast to sources with ordinary temperatures and fields), if they lie within a few kpc. The quantum TS spectra are too soft to account for the hard components (up to tens of MeV) of the GRB spectra detected by the Solar Maximum Mission (Nolan et al., 1984), unless the temperatures are unreasonably high. A straightforward TS interpretation of the GRB spectra seems to be unrealistic. Most probably, the continuum radiation escapes from an optically thick, strongly magnetized, highly non-stationary, hot plasma near the surface of a neutron star.

UR - http://www.scopus.com/inward/record.url?scp=7544219953&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=7544219953&partnerID=8YFLogxK

U2 - 10.1007/BF00644582

DO - 10.1007/BF00644582

M3 - Article

VL - 128

SP - 341

EP - 354

JO - Astrophysics and Space Science

JF - Astrophysics and Space Science

SN - 0004-640X

IS - 2

ER -