scholarly journals ROLE OF THE 3.6M DOT TO INVESTIGATE CONNECTIONS BETWEEN LONG-GRBS AND CORE-COLLAPSE SNE

2021 ◽  
Vol 53 ◽  
pp. 127-133
Author(s):  
A. Kumar ◽  
S. B. Pandey ◽  
R. Gupta ◽  
A. Aryan ◽  
A. J. Castro-Tirado ◽  
...  
Keyword(s):  
Time Domain ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Global Network ◽  
Core Collapse ◽  
Robotic Telescopes ◽  
The Time Domain ◽  
Time Critical ◽  
Near Future

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 In this study, we present an analysis of unpublished R-band data of GRB 171205A/SN 2017iuk spanning between ~12 to 105 days since burst, that observed using the 3.6m DOT with 4K × 4K CCD Imager.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.

Gamma-ray bursts: the time domain

1995 ◽  
Vol 231 (1-2) ◽  
pp. 95-102 ◽  
Author(s):  
Jay P. Norris
Keyword(s):  
Time Domain ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
The Time Domain

scholarly journals Characteristic Variability Time Scales of Long Gamma-Ray Bursts

2003 ◽  
Vol 214 ◽  
pp. 339-340
Author(s):  
Rongfeng Shen ◽  
Liming Song
Keyword(s):  
Power Density ◽  
Time Scales ◽  
Time Domain ◽  
Time Scale ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Time Dilation ◽  
Dilation Effect ◽  
The Time Domain ◽  
Intrinsic Characteristic

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.

scholarly journals DIVISION IV / WORKING GROUP MASSIVE STARS

2008 ◽  
Vol 4 (T27A) ◽  
pp. 236-239
Author(s):  
Stanley P. Owocki ◽  
Paul A. Crowther ◽  
Alexander W. Fullerton ◽  
Gloria Koenigsberger ◽  
Norbert Langer ◽  
...  
Keyword(s):  
Working Group ◽  
Gamma Ray ◽  
Massive Stars ◽  
Gamma Ray Bursts ◽  
Core Collapse ◽  
Hot Stars ◽  
First Stars ◽  
Ob Stars ◽  
Red Supergiants

Our Working Group studies massive, luminous stars, with historical focus on early-type (OB) stars, but extending in recent years to include massive red supergiants that evolve from hot stars. There is also emphasis on the role of massive stars in other branches of astrophysics, particularly regarding starburst galaxies, the first stars, core-collapse gamma-ray bursts, and formation of massive stars.

scholarly journals Lightweight Unmanned Aerial System for Time-Domain Electromagnetic Prospecting—The Next Stage in Applied UAV-Geophysics

2021 ◽  
Vol 11 (5) ◽  
pp. 2060 ◽  
Author(s):  
Alexander Parshin ◽  
Ayur Bashkeev ◽  
Yuriy Davidenko ◽  
Marina Persova ◽  
Sergey Iakovlev ◽  
...  
Keyword(s):  
Time Domain ◽  
Gamma Ray ◽  
Pulse Generator ◽  
Measuring System ◽  
Electromagnetic Sounding ◽  
Mountainous Regions ◽  
Time Domain Electromagnetic ◽  
Unmanned System ◽  
Classical Triad ◽  
The Time Domain

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.

scholarly journals Luminous supernovae associated with ultra-long gamma-ray bursts from hydrogen-free progenitors extended by pulsational pair-instability

2020 ◽  
Vol 641 ◽  
pp. L10
Author(s):  
Takashi J. Moriya ◽  
Pablo Marchant ◽  
Sergei I. Blinnikov
Keyword(s):  
Light Curve ◽  
Energy Input ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Core Collapse ◽  
Decay Energy ◽  
Slow Cooling ◽  
Gamma Ray Burst ◽  
The Core ◽  
Optical Light Curve

We show that the luminous supernovae associated with ultra-long gamma-ray bursts can be related to the slow cooling from the explosions of hydrogen-free progenitors that are extended by pulsational pair-instability. We have recently shown that some rapidly-rotating hydrogen-free gamma-ray burst progenitors that experience pulsational pair-instability can keep an extended structure caused by pulsational pair-instability until the core collapse. These types of progenitors have large radii exceeding 10 R⊙ and they sometimes reach beyond 1000 R⊙ at the time of the core collapse. They are, therefore, promising progenitors of ultra-long gamma-ray bursts. Here, we perform light-curve modeling of the explosions of one extended hydrogen-free progenitor with a radius of 1962 R⊙. The progenitor mass is 50 M⊙ and 5 M⊙ exists in the extended envelope. We use the one-dimensional radiation hydrodynamics code STELLA in which the explosions are initiated artificially by setting given explosion energy and 56Ni mass. Thanks to the large progenitor radius, the ejecta experience slow cooling after the shock breakout and they become rapidly evolving (≲10 days), luminous (≳1043 erg s−1) supernovae in the optical even without energy input from the 56Ni nuclear decay when the explosion energy is more than 1052 erg. The 56Ni decay energy input can affect the light curves after the optical light-curve peak and make the light-curve decay slowly when the 56Ni mass is around 1 M⊙. They also have a fast photospheric velocity above 10 000 km s−1 and a hot photospheric temperature above 10 000 K at around the peak luminosity. We find that the rapid rise and luminous peak found in the optical light curve of SN 2011kl, which is associated with the ultra-long gamma-ray burst GRB 111209A, can be explained as the cooling phase of the extended progenitor. The subsequent slow light-curve decline can be related to the 56Ni decay energy input. The ultra-long gamma-ray burst progenitors we proposed recently can explain both the ultra-long gamma-ray burst duration and the accompanying supernova properties. When the gamma-ray burst jet is off-axis or choked, the luminous supernovae could be observed as fast blue optical transients without accompanying gamma-ray bursts.

scholarly journals EXPLORING THE TRANSIENT SKY WITH THE FLY'S EYE CAMERA SYSTEM

2019 ◽  
Vol 51 ◽  
pp. 116-123
Author(s):  
L. Mészáros ◽  
A. Pál ◽  
G. Csépány ◽  
K. Vida ◽  
L. Kriskovics ◽  
...  
Keyword(s):  
Time Domain ◽  
Degrees Of Freedom ◽  
Gamma Ray ◽  
Parallel Robots ◽  
Camera System ◽  
Transient Event ◽  
Astrophysical Objects ◽  
Robotic Telescopes ◽  
Fast Transients ◽  
6 Degrees Of Freedom

To study astrophysical transit phenomena we follow an alternative strategy for getting high-cadence observations of the field. This can be achieved with our new Fly’s Eye Camera System that monitors the entire sky above 30◦ horizontal altitude. With this instrument one can observe all phenomena brighter than ∼ 15m in Sloan r-band (u’, g’,i’ and z’ filters are also available). If we stack together a few hour of images we canobserve ∼ 17 m faint sources. This small-sized instrument is designed for time-domain astronomy with its 150 sec cadence. Due to the hexapod-based motion control, the instrument can be installed anywhere without any modifications, it can accomplish sky tracking automatically. These parallel robots have 6 degrees of freedom (DoF), but since any kind of rotation can be done by using only 3 DoF, the tracking with hexapods is independent from the geographical coordinates. Even polar alignment is not required, because Fly’s Eye can calibrate itself based on its own observed data. The system is optimal for time-domain astronomy: detecting novae, supernovae, optical afterglows of gamma-ray bursts and other bright, fast transients, and, from the observation database such data can be obtained - even from before the discovery of the transient event. In the future when the direction of the gravitational waves will be defined precisely we will be able to detect their first multiwaveband counterparts. In addition the Fly’s Eye will support the “Transient Astrophysical Objects” project which will use two new 80 cm robotic telescopes for follow-up observations of transients.

scholarly journals Stellar Core Collapse and Exotic Matter

2011 ◽  
Vol 7 (S279) ◽  
pp. 367-368
Author(s):  
Ken'ichiro Nakazato ◽  
Kohsuke Sumiyoshi
Keyword(s):  
Black Hole ◽  
Degrees Of Freedom ◽  
Gamma Ray ◽  
Dense Matter ◽  
Gamma Ray Bursts ◽  
Core Collapse ◽  
Hole Formation ◽  
Stellar Core ◽  
Black Hole Formation ◽  
Hydrodynamical Simulations

AbstractSome supernovae and gamma-ray bursts are thought to accompany a black hole formation. In the process of a black hole formation, a central core becomes hot and dense enough for hyperons and quarks to appear. In this study, we perform neutrino-radiation hydrodynamical simulations of a stellar core collapse and black hole formation taking into account such exotic components. In our computation, general relativity is fully considered under spherical symmetry. As a result, we find that the additional degrees of freedom soften the equation of state of matter and promote the black hole formation. Furthermore, their effects are detectable as a neutrino signal. We believe that the properties of hot and dense matter at extreme conditions are essential for the studies on the astrophysical black hole formation. This study will be hopefully a first step toward a physics of the central engine of gamma-ray bursts.

VARIABILITY PROPERTIES OF SWIFT-BAT GAMMA-RAY BURSTS

2011 ◽  
Vol 20 (10) ◽  
pp. 1969-1973 ◽  
Author(s):  
RAFFAELLA MARGUTTI ◽  
CRISTIANO GUIDORZI ◽  
GUIDO CHINCARINI
Keyword(s):  
Energy Range ◽  
Time Scales ◽  
Time Scale ◽  
Rest Frame ◽  
Gamma Ray ◽  
Timing Analysis ◽  
Gamma Ray Bursts ◽  
Cosmological Time ◽  
The Time Domain ◽  
Prompt Emission

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.

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