Gamma-ray bursts: the time domain

1995 ◽  
Vol 231 (1-2) ◽  
pp. 95-102 ◽  
Author(s):  
Jay P. Norris
Author(s):  
A. Kumar ◽  
S. B. Pandey ◽  
R. Gupta ◽  
A. Aryan ◽  
A. J. Castro-Tirado ◽  
...  

Newly installed 3.6m DOT at Nainital (Uttarakhand) is a novel facility for the time domain astronomy. Because of the longitudinal advantage of India, it could be used to study new transients reported by a global network of robotic telescopes. Observations with the 4K × 4K CCD Imager at the axial port of the 3.6m DOT will be very helpful in the near future towards understanding the different physical aspects of time-critical events, e.g., Gamma-ray bursts (GRBs), Supernovae, Gravitational wave candidates, etc. Using the Imager with broadband filters (Bessel UBVRI and SDSS ugriz), ~6.5' × 6.5' images could be obtained to attempt various science goals in synergy with other multi-band facilities. In this study, we present an analysis of unpublished R-band data of GRB 171205A/SN 2017iuk spanning between ~12 to 105 days since burst, that observed using the 3.6m DOT with 4K × 4K CCD Imager. In the R-band light curve, a bump appears to start from ~3 days, which shows the peak at ~15 days after the burst, clearly indicates photometric evidence of association of SN with GRB 171205A.


2003 ◽  
Vol 214 ◽  
pp. 339-340
Author(s):  
Rongfeng Shen ◽  
Liming Song

We determine the characteristic variability time scales for 410 bright long GRBs by locating the maximums of their Power Density Spectra (PDSs) defined and calculated in the time domain. The averaged characteristic variability time scale decreases with peak fluxe. This is consistent with the time dilation effect expected by cosmological origin of GRBs. The occurrence distribution of the characteristic variability time scale shows bimodality, which might be interpreted as that the long GRB sample is composed of two sub-classes with different intrinsic characteristic variability time scales.


2021 ◽  
Vol 11 (5) ◽  
pp. 2060 ◽  
Author(s):  
Alexander Parshin ◽  
Ayur Bashkeev ◽  
Yuriy Davidenko ◽  
Marina Persova ◽  
Sergey Iakovlev ◽  
...  

Nowadays in solving geological problems, the technologies of UAV-geophysics, primarily magnetic and gamma surveys, are being increasingly used. However, for the formation of the classical triad of airborne geophysics methods in the UAV version, there was not enough technology for UAV-electromagnetic sounding, which would allow studying the geological environment at depths of tens and hundreds of meters with high detail. This article describes apparently the first technology of UAV-electromagnetic sounding in the time domain (TDEM, TEM), implemented as an unmanned system based on a light multi-rotor UAV. A measuring system with an inductive sensor—an analogue of a 20 × 20 or 50 × 50 m receiving loop is towed by a UAV, and a galvanically grounded power transmitter is on the ground and connected to a pulse generator. The survey is carried out along a network of parallel lines at low altitude with a terrain draping at a speed of 7–8 m/s, the maximum distance of the UAV’s departure from the transmitter line can reach several kilometers, thus the created technology is optimal for performing detailed areal electromagnetic soundings in areas of several square kilometers. The results of the use of the unmanned system (UAS) in real conditions of the mountainous regions of Eastern Siberia are presented. Based on the obtained data, the sensitivity of the system was simulated and it was shown that the developed technology allows one to collect informative data and create geophysical sections and maps of electrical resistivity in various geological situations. According to the authors, the emergence of UAV-TEM systems in the near future will significantly affect the practice of geophysical work, as it was earlier with UAV-magnetic prospecting and gamma-ray survey.


2011 ◽  
Vol 20 (10) ◽  
pp. 1969-1973 ◽  
Author(s):  
RAFFAELLA MARGUTTI ◽  
CRISTIANO GUIDORZI ◽  
GUIDO CHINCARINI

We study the variability properties of the prompt emission of Gamma-Ray Bursts in the gamma-ray energy range. We use the power spectrum analysis in the time domain as developed by [Margutti, in preparation]; this technique is suitable to study the rms variations at different time scales. The timing analysis of 252 Swift light-curves in the 15–150 keV energy range reveals the existence of different variability classes. Moreover, after accounting for the cosmological time dilation, the distribution of the GRB characteristic variability time scales is found to cluster around 0.6–1 s we identify this time scale as a characteristic variability time scale of long GRBs in the source rest frame.


Author(s):  
Simon Vaughan

Progress in astronomy comes from interpreting the signals encoded in the light received from distant objects: the distribution of light over the sky (images), over photon wavelength (spectrum), over polarization angle and over time (usually called light curves by astronomers). In the time domain, we see transient events such as supernovae, gamma-ray bursts and other powerful explosions; we see periodic phenomena such as the orbits of planets around nearby stars, radio pulsars and pulsations of stars in nearby galaxies; and we see persistent aperiodic variations (‘noise’) from powerful systems such as accreting black holes. I review just a few of the recent and future challenges in the burgeoning area of time domain astrophysics, with particular attention to persistently variable sources, the recovery of reliable noise power spectra from sparsely sampled time series, higher order properties of accreting black holes, and time delays and correlations in multi-variate time series.


Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 28 ◽  
Author(s):  
Frank Rieger

The last few years have seen gamma-ray astronomy maturing and advancing in the field of time-domain astronomy, utilizing source variability on timescales over many orders of magnitudes, from a decade down to a few minutes and shorter, depending on the source. This review focuses on some of the key science issues and conceptual developments concerning the timing characteristics of active galactic nuclei (AGN) at gamma-ray energies. It highlights the relevance of adequate statistical tools and illustrates that the developments in the gamma-ray domain bear the potential to fundamentally deepen our understanding of the nature of the emitting source and the link between accretion dynamics, black hole physics, and jet ejection.


2019 ◽  
Vol 213 ◽  
pp. 02105 ◽  
Author(s):  
Marcin Zych ◽  
Robert Hanus ◽  
Marek Jaszczur ◽  
Anna Golijanek-Jędrzejczyk ◽  
Dariusz Świsulski ◽  
...  

The article presents the analysis of signals from a radiometric system consisting of two scintillation probes and two gamma radiation sealed sources. Calculations and interpretation were carried out for the bubble flow of the water-air mixture in the horizontal pipeline. The analysis of the obtained signals was done in time and frequency domain. In the frequency domain, a range of usable frequencies was identified, which were associated with changes in gamma-ray intensity recorded in the time domain. The gas phase velocity, void fraction and statistical parameters of the signal were also calculated.


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