Gamma-ray burst measurements at low fluxes

1981 ◽  
Vol 301 (1462) ◽  
pp. 661-663
Keyword(s):  
Power Law ◽  
Gamma Ray ◽  
The Other ◽  
Source Distribution ◽  
Gamma Ray Burst ◽  
Thick Disc ◽  
Other Hand ◽  
Source Models ◽  
Arrival Directions

Recent measurements of the number of cosmic y-ray bursts per year at small flux levels continue to show significant deviations from the N (> S ) S -3/2 power law for the rate N ( > S ) at size S which would apply to a uniform source distribution. In particular Fishman et al. (1978) and Agrawal et al. (1979) find flux limits two orders of magnitude lower than those expected when the Vela (Strong & Klebesadel 1974) data are extrapolated by the S -3/2 -law to flux levels 5 x 10 -8 erg cm -2 . Spherical halo, monoluminosity source distributions discussed by Jennings & White (1980) have failed to satisfy these data although they are consistent with triangulation results obtained by spacecraft networks on a few individual burst arrival directions (Hurley 1980). On the other hand, thick disc source models seem to satisfy the observed lg N -lg S distribution.

scholarly journals Comparison of gamma ray effects on EPROMs and E2PROMs

2009 ◽  
Vol 24 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Milos Vujisic ◽  
Koviljka Stankovic ◽  
Aleksandra Vasic
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Radiation Hardness ◽  
The Other ◽  
Other Hand ◽  
Read Only Memory ◽  
Ray Effects

This paper compares the reliability of standard commercial Erasable Programmable Read Only Memory (EPROM) and Electrically Erasable Programmable Read Only Memory (E2PROM) components exposed to gamma rays. The results obtained for CMOS-based EPROM (NM27C010) and E2PROM (NM93CS46) components provide the evidence that EPROMs have greater radiation hardness than E2PROMs. Moreover, the changes in EPROMs are reversible, and after erasure and reprogramming all EPROM components restore their functionality. On the other hand, changes in E2PROMs are irreversible. The obtained results are analyzed and interpreted on the basis of gamma ray interaction with the CMOS structure.

scholarly journals LUMINOSITIES OF RADIO PULSARS

2013 ◽  
Vol 22 (10) ◽  
pp. 1330021 ◽  
Author(s):  
MANJARI BAGCHI
Keyword(s):  
Power Law ◽  
Globular Clusters ◽  
Galactic Disk ◽  
Intrinsic Property ◽  
Magnetospheric Plasma ◽  
The Other ◽  
Radio Pulsars ◽  
Beam Geometry ◽  
Other Hand ◽  
Open Questions

Luminosity is an intrinsic property of radio pulsars related to the properties of the magnetospheric plasma and the beam geometry, and inversely proportional to the observing frequency. In traditional models, luminosity has been considered as a function of the spin parameters of pulsars. On the other hand, parameter independent models like power law and lognormal have been also used to fit the observed luminosities. Some of the older studies on pulsar luminosities neglected observational biases, but all of the recent studies tried to model observational effects as accurately as possible. Luminosities of pulsars in globular clusters (GCs) and in the Galactic disk have been studied separately. Older studies concluded that these two categories of pulsars have different luminosity distributions, but the most recent study concluded that those are the same. This paper reviews all significant works on pulsar luminosities and discusses open questions.

scholarly journals GRB 190114C: from prompt to afterglow?

2019 ◽  
Vol 626 ◽  
pp. A12 ◽  
Author(s):  
M. E. Ravasio ◽  
G. Oganesyan ◽  
O. S. Salafia ◽  
G. Ghirlanda ◽  
G. Ghisellini ◽  
...  
Keyword(s):  
Energy Range ◽  
Power Law ◽  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
Onset Time ◽  
Lorentz Factor ◽  
Spectral Energy ◽  
Large Area ◽  
Spectral Evolution ◽  
Gamma Ray Burst

GRB 190114C is the first gamma-ray burst detected at very high energies (VHE, i.e., > 300 GeV) by the MAGIC Cherenkov telescope. The analysis of the emission detected by the Fermi satellite at lower energies, in the 10 keV–100 GeV energy range, up to ∼50 s (i.e., before the MAGIC detection) can hold valuable information. We analyze the spectral evolution of the emission of GRB 190114C as detected by the Fermi Gamma-Ray Burst Monitor (GBM) in the 10 keV–40 MeV energy range up to ∼60 s. The first 4 s of the burst feature a typical prompt emission spectrum, which can be fit by a smoothly broken power-law function with typical parameters. Starting on ∼4 s post-trigger, we find an additional nonthermal component that can be fit by a power law. This component rises and decays quickly. The 10 keV–40 MeV flux of the power-law component peaks at ∼6 s; it reaches a value of 1.7 × 10−5 erg cm−2 s−1. The time of the peak coincides with the emission peak detected by the Large Area Telescope (LAT) on board Fermi. The power-law spectral slope that we find in the GBM data is remarkably similar to that of the LAT spectrum, and the GBM+LAT spectral energy distribution seems to be consistent with a single component. This suggests that the LAT emission and the power-law component that we find in the GBM data belong to the same emission component, which we interpret as due to the afterglow of the burst. The onset time allows us to estimate that the initial jet bulk Lorentz factor Γ0 is about 500, depending on the assumed circum-burst density.

scholarly journals A Bayesian Fermi-GBM short GRB spectral catalogue

2019 ◽  
Vol 490 (1) ◽  
pp. 927-946 ◽  
Author(s):  
J Michael Burgess ◽  
Jochen Greiner ◽  
Damien Bégué ◽  
Franceso Berlato
Keyword(s):  
Light Curve ◽  
Gravitational Wave ◽  
Power Law ◽  
Gamma Ray ◽  
Posterior Distributions ◽  
Time Resolved ◽  
Gamma Ray Burst ◽  
Posterior Predictive Checks ◽  
Peak Flux ◽  
Reduced Data

ABSTRACT Inspired by the confirmed detection of a short gamma-ray burst (GRB) in association with a gravitational wave signal, we present the first Bayesian Fermi-Gamma-ray Burst Monitor (GBM) short GRB spectral catalogue. Both peak flux and time-resolved spectral results are presented. Data are analysed with the proper Poisson likelihood allowing us to provide statistically reliable results even for spectra with few counts. All fits are validated with posterior predictive checks. We find that nearly all spectra can be modelled with a cut-off power law. Additionally, we release the full posterior distributions and reduced data from our sample. Following our previous study, we introduce three variability classes based on the observed light-curve structure.

scholarly journals Luminosity Distribution of Gamma-ray Burst Optical Afterglows

2012 ◽  
Vol 8 (S290) ◽  
pp. 335-336
Author(s):  
X. G. Wang ◽  
E. W. Liang ◽  
L. Li ◽  
J. J. Wei ◽  
B. Zhang
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Power Law ◽  
Luminosity Function ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Gamma Ray Burst

AbstractWe derive the optical afterglow luminosity distributions at different epoches for gamma-ray bursts (GRBs) from a sample of 146 GRBs that have a well-sampled optical afterglow lightcurve, then explore the luminosity function of GRB optical afterglows using the Monte Carlo simulation. We show that an intrinsic broken power-law luminosity function can well reproduced the observed magnitude distributions.

scholarly journals A test of the power-law relationship between gamma-ray burst pulse-width ratio and energy expected in fireballs and uniform jets

2006 ◽  
Vol 368 (3) ◽  
pp. 1351-1358 ◽  
Author(s):  
Z.-Y. Peng ◽  
Y.-P. Qin ◽  
B.-B. Zhang ◽  
R.-J. Lu ◽  
L.-W. Jia ◽  
...  
Keyword(s):  
Power Law ◽  
Pulse Width ◽  
Gamma Ray ◽  
Width Ratio ◽  
Gamma Ray Burst ◽  
Burst Pulse

scholarly journals Chandra observations of black widow pulsars

2012 ◽  
Vol 8 (S291) ◽  
pp. 389-391 ◽  
Author(s):  
P. Gentile ◽  
M. McLaughlin ◽  
M. Roberts ◽  
F. Camilo ◽  
J. Hessels ◽  
...  
Keyword(s):  
Power Law ◽  
Gamma Ray ◽  
The Other ◽  
Emission Characteristic ◽  
Black Widow ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Significant Variability ◽  
Binary Orbit

AbstractWe describe the first X-ray observations of binary millisecond pulsars PSR J0023+0923, J1810+1744, J2215+5135, and J2256−1024. All are Fermi gamma-ray sources and three are ‘black-widow’ pulsars, with companions of mass < 0.1 M⊙. Data were taken using the Chandra X-Ray Observatory and covered a full binary orbit for each pulsar. PSRs J2215+5135 and J2256−1024, show significant orbital variability and X-ray flux minima coinciding with eclipses seen at radio wavelengths. This is consistent with intrabinary shock emission characteristic of black-widow pulsars. The other two pulsars, PSRs J0023+0923 and J1810+1744, do not demonstrate significant variability, but are fainter than the other two sources. Spectral fits yield power-law indices that range from 1.4 to 2.3 and blackbody temperatures in the hundreds of eV. The spectrum for PSR J2215+5135 shows a significant hard X-ray component (41% of counts are above 2 keV), which is additional evidence for the presence of intrabinary shock emission.

scholarly journals FERMIOBSERVATIONS OF GRB 090510: A SHORT-HARD GAMMA-RAY BURST WITH AN ADDITIONAL, HARD POWER-LAW COMPONENT FROM 10 keV TO GeV ENERGIES

2010 ◽  
Vol 716 (2) ◽  
pp. 1178-1190 ◽  
Author(s):  
M. Ackermann ◽  
K. Asano ◽  
W. B. Atwood ◽  
M. Axelsson ◽  
L. Baldini ◽  
...  
Keyword(s):  
Power Law ◽  
Gamma Ray ◽  
Gamma Ray Burst ◽  
Hard Power
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