Gamma Ray Bursts

Since their discovery was first announced in 1973, gamma-ray bursts (GRBs) have been among the most fascination objects in the universe.

Author: Gilbert Vedrenne

Publisher: Springer Science & Business Media

ISBN: 354039088X

Category: Science

Page: 580

View: 942

Since their discovery was first announced in 1973, gamma-ray bursts (GRBs) have been among the most fascination objects in the universe. While the initial mystery has gone, the fascination continues, sustained by the close connection linking GRBs with some of the most fundamental topics in modern astrophysics and cosmology. Both authors have been active in GRB observations for over two decades and have produced an outstanding account on both the history and the perspectives of GRB research.

Gamma Ray Bursts 30 Years of Discovery

In the last thirty years, gamma-ray bursts have grown from an oddity to a central position in astrophysics.

Author: E.E. Fenimore

Publisher: Amer Inst of Physics

ISBN:

Category: Science

Page: 812

View: 489

In the last thirty years, gamma-ray bursts have grown from an oddity to a central position in astrophysics. Not only are they the largest explosions since the big bang, capable of flooding most of the universe with gamma-rays, but their brilliance serves as a backlight that can illuminate the cosmos far deeper into the early universe than any other object. Their unpredictability has forced researchers to use extreme measures to observe them: completely autonomous satellites and robotic ground-based telescopes. Their bizarre physical properties have pushed us to develop new theories of astrophysical explosions. Topics include: global properties of GRBs; X-ray flashes; ultra-high energy gamma-rays, neutrinos, gravity waves; prompt emission and early afterglows; relativistic jets and polarization; GRB030329; GRB progenitors; GRB connection to supernovae; dark versus bright GRBs; late afterglows; GRBs and cosmology; general observations; general theory; analysis and observation techniques; present satellites; Swift satellite; future satellites; and robotic observing systems.


Toward an Understanding of the Progenitors of Gamma Ray Bursts

This is naturally explained by bursts which originate from the collapse of massive stars ``collapsars'').

Author: Joshua S. Bloom

Publisher: Universal-Publishers

ISBN: 1581121695

Category: Science

Page: 200

View: 884

The various possibilities for the origin ("progenitors") of gamma-ray bursts (GRBs) manifest in differing observable properties. Through deep spectroscopic and high-resolution imaging observations of some GRB hosts, I demonstrate that well-localized long-duration GRBs are connected with otherwise normal star-forming galaxies at moderate redshifts of order unity. Using high-mass binary stellar population synthesis models, I quantify the expected spatial extent around galaxies of coalescing neutron stars, one of the leading contenders for GRB progenitors. I then test this scenario by examining the offset distribution of GRBs about their apparent hosts making extensive use of ground-based optical data from Keck and Palomar and space-based imaging from the Hubble Space Telescope. The offset distribution appears to be inconsistent with the coalescing neutron star binary hypothesis (and, similarly, black-hole--neutron star coalescences); instead, the distribution is statistically consistent with a population of progenitors that closely traces the ultra-violet light of galaxies. This is naturally explained by bursts which originate from the collapse of massive stars ``collapsars''). This claim is further supported by the unambiguous detections of intermediate-time (approximately three weeks after the bursts) emission ``bumps'' which appear substantially more red than the afterglows themselves. I claim that these bumps could originate from supernovae that occur at approximately the same time as the associated GRB; if true, GRB 980326 and GRB 011121 provide strong observational evidence connecting cosmological GRBs to high-redshift supernovae and implicate massive stars as the progenitors of at least some long-duration GRBs.

Gamma Ray Bursts

This book reflects the current state of the growing field of gamma-ray burst research and the remarkable progress brought about by recent multiwavelength observations.

Author: R. Marc Kippen

Publisher: American Institute of Physics

ISBN: 9781563969478

Category: Science

Page: 936

View: 991

This book reflects the current state of the growing field of gamma-ray burst research and the remarkable progress brought about by recent multiwavelength observations. A full range of topics related to modern burst research is covered, including new observational results, ongoing archival analyses, theoretical modeling, and current/future instrumentation.



High Velocity Neutron Stars and Gamma Ray Bursts

Reproduced from typescripts. No subject index. Annotation c. by Book News, Inc., Portland, Or.

Author: Richard E. Rothschild

Publisher: Amer Inst of Physics

ISBN:

Category: Science

Page: 282

View: 610

Annotation When two sets of observations suggested the exciting possibility that all gamma-ray bursts might be related to a population of high-velocity neutron stars, perhaps inhabiting an extended halo of the galaxy, a conference was soon called by wives and colleagues so that researchers could talk to each other about it. The 48 papers cover radio observations and origins of high- velocity neutron stars, observations and theories of soft gamma- ray repeaters, classical gamma-ray burst observations, repetition and spectroscopy, and classical gamma-ray burst theories. Reproduced from typescripts. No subject index. Annotation c. by Book News, Inc., Portland, Or.

Systematical Uncertainties in the Measurement of a Gamma ray Burst s Isotropic Equivalent Energy

In this work I focus on a few particular analytical choices that any analyst can make differently from the next, leading to inconsistent Eiso values measured for the same GRB event.

Author: Kimberly Zoldak

Publisher:

ISBN:

Category:

Page: 712

View: 406

Gamma-ray Bursts (GRBs) are the most energetic and luminous explosions in the Universe since the Big Bang, enabling them to be observed out to extremely large redshifts (z9̃). Consequently, this makes them a promising cosmological standard candle candidate. Unfortunately, however, they have proven to be quite challenging to standardize. The GRB community has worked tirelessly at this task, and to date, has put forth several luminosity-distance relations, some more propitious than others. The most prevailing problem with these relations is in their sizable amount of scatter, likely due to measurement inconsistencies and errors in the variables they employ. This arises when the results from many independent analysts are combined, which cumulates their individual choices in methods and methodologies. In this dissertation I examine the systematical uncertainties associated with the calculation of a GRB's isotropical equivalent energy, Eiso. This energetic is attributed to the total energy that is released by a GRB's central engine in the form of X-rays and gamma-rays, before becoming reprocessed down-jet into radiation spanning the entire electromagnetic spectrum. Not only does Eiso have physical implications for GRBs, but it is employed by two of the most widely recognizable luminosity-distance relations: the Amati and the Ghirlanda relations. Our greatest concern with Eiso is that, historically, it has not been measured with a high level of consistency, which may be leading to significant scatter and bias for these two relations. Whenever a relation's variables suffer from significant measurement errors, the relations themselves also accrue these errors, thereby increasing their scatter and decreasing their reliability. In this dissertation I present the most comprehensive exploration into the systematical uncertainties of Eiso that has ever been done. In this work I focus on a few particular analytical choices that any analyst can make differently from the next, leading to inconsistent Eiso values measured for the same GRB event. I act as two independent analysts by altering a single analytical choice between the two analyses that are performed on the same subset of GRBs. This provides us with a measure of uncertainty that is associated with each particular analytical choice. In addition to quantifying uncertainties, I examine and discuss the minutiae of the spectral modeling parameters that are used to characterize a GRB's fluence spectrum and thus its Eiso. To achieve our goals, I employed Fermi Gamma-ray Space Telescope GRB data for a sample of events with redshifts measured from ground-based follow-up optical/NIR spectroscopy. To ensure that data preparation uncertainties remained minimal, we performed all of our own data reductions, fluence spectral modeling, and Eiso calculations for this work, rather than adopting values from the literature.

Gamma Ray Burst

This was a technical symposium for astrophysicists working on gamma-ray bursts. It included discussions on the latest theoretical and experimental research on this topic, as well as plans for the next generation of orbiting instrumentation.

Author: Charles Meegan

Publisher: American Institute of Physics

ISBN:

Category: Science

Page: 537

View: 777

Alabama, 20-23 October 2008