Photon emission in a cascade from relativistic protons initiated by residual thermal photons in gamma-ray bursts

被引:16
作者
Asano, K [1 ]
Takahara, F [1 ]
机构
[1] Osaka Univ, Dept Earth & Space Sci, Toyonaka, Osaka 5600043, Japan
关键词
gamma rays : bursts; non-thermal; radiation mechanisms : shock waves;
D O I
10.1093/pasj/55.2.433
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Gamma-ray bursts are generally considered to be the result of internal shocks generated in an inhomogeneous relativistic outflow that arises from a fireball. In such shocks, the Fermi acceleration of protons is naturally expected to be at least as efficient as that of electrons. We investigate the consequences of proton acceleration in the residual thermal photon field of a fireball, especially those on the emission spectra of photons. In contrast to most other studies, we do not invoke a direct electron acceleration in shock waves. We show that the residual radiation field of the fireball can ignite the photopion production and subsequent cascade, and that the photons emitted in this process further enhance the photon-initiated cascade. We find that Fermi-accelerated protons with greater than or similar to 10(13) eV efficiently bring their energy into pion production and subsequent photon emission. The particles cascading from the pions emit photons over a wide energy range. The photons emitted from electron-positron pairs distribute continuously from the GeV range down to the X-ray range, while muons can emit gamma-rays by synchrotron radiation with a break at around 1-10 MeV. We also discuss several radiation processes which may possibly produce a break feature in the MeV range, as observed in addition to muon synchrotron radiation.
引用
收藏
页码:433 / 444
页数:12
相关论文
共 29 条
[1]  
[Anonymous], APJ
[2]  
[Anonymous], APJ
[3]  
Berestetskii V.B., 1982, QUANTUM ELECTRODYNAM, P371
[4]   TIME-DEPENDENT MODELS OF MAGNETIZED PAIR PLASMAS [J].
COPPI, PS .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1992, 258 (04) :657-683
[5]   Efficiency and spectrum of internal gamma-ray burst shocks [J].
Guetta, D ;
Spada, M ;
Waxman, E .
ASTROPHYSICAL JOURNAL, 2001, 557 (01) :399-407
[6]   SPECTRAL AND VARIABILITY CONSTRAINTS ON COMPACT SOURCES [J].
GUILBERT, PW ;
FABIAN, AC ;
REES, MJ .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1983, 205 (02) :593-603
[7]   X-ray flashes and X-ray rich gamma ray bursts [J].
Heise, J ;
in 't Zand, J ;
Kippen, RM ;
Woods, PM .
GAMMA-RAY BURSTS IN THE AFTERGLOW ERA, 2001, :16-21
[8]   BATSE observations of fast X-ray transients detected by BeppoSAX-WFC [J].
Kippen, RM ;
Woods, PM ;
Heise, J ;
in't Zand, J ;
Preece, RD ;
Briggs, MS .
GAMMA-RAY BURSTS IN THE AFTERGLOW ERA, 2001, :22-25
[9]   Ultraefficient internal shocks [J].
Kobayashi, S ;
Sari, R .
ASTROPHYSICAL JOURNAL, 2001, 551 (02) :934-939
[10]   GAMMA-RAY BURST PRECURSOR ACTIVITY AS OBSERVED WITH BATSE [J].
KOSHUT, TM ;
KOUVELIOTOU, C ;
PACIESAS, WS ;
VANPARADIJS, J ;
PENDLETON, GN ;
BRIGGS, MS ;
FISHMAN, GJ ;
MEEGAN, CA .
ASTROPHYSICAL JOURNAL, 1995, 452 (01) :145-155