摘要:

We use a stellar binary population synthesis code to find the lifetimes and velocities of several types of possible GRB progenitors: double neutron stars, black holes and neutron stars, black holes and neutron stars, black holes and white dwarfs, and helium stars. Assuming that they are born in different types of galaxies, we compute their spatial distribution and compare it with the observed locations of GRB afterglows within their hosts. We discuss constraints on the compact object merger model of GRBs imposed by this comparison and find that the observations of afterglows and their host galaxies appear inconsistent with the GRB compact object merger model. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361616

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

GRBs have redshifts comparable to, perhaps even larger than those of quasars. Indeed, they are the most energetic explosions in the universe, with energies of orderM⊙c2.Their host galaxies are faint, but are actively forming stars at rates typical of galaxies in the early universe. The current paradigm associates GRBs with the formation of black holes in massive, rotating stars, or with the mergers of compact binaries. GRBs thus trace the cosmic star formation rate and may be the most easily detectable emission of the earliest generation of stars. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361617

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We show that, if many GRBs are indeed produced by the collapse of massive stars, GRBs and their afterglows provide a powerful probe of the very high redshift(z≳5)universe. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361618

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The lack of detection of a gravitational lens signature on gamma-ray bursts (GRBs) places limits on cosmological geometry and the mass fraction of compact objects in the universe. We report on two new searches we have done for macro- and millilensing of GRBs and their corresponding limits. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361619

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Swift is a first of its kind multiwavelength transient observatory for gamma-ray burst astronomy. It has the optimum capabilities for the next breakthroughs in determining the origin of gamma-ray bursts and their afterglows as well as using bursts to probe the early Universe. Swift will also perform the first sensitive hard X-ray survey of the sky. The mission is being developed by an international collaboration and consists of three instruments, the Burst Alert Telescope (BAT), the X-ray Telescope (XRT), and the Ultraviolet and Optical Telescope (UVOT). The BAT, a wide-field gamma-ray detector, will detect ∼1 gamma-ray burst per day with a sensitivity 5 times that of BATSE. The sensitive narrow-field XRT and UVOT will be autonomously slewed to the burst location in 20 to 70 seconds to determine 0.3–2.5 arcsec positions and perform optical, UV, and X-ray spectrophotometry. On-board measurements of redshift will also be done for hundreds of bursts. Swift will incorporate superb, low-cost instruments using existing flight-spare hardware and designs. Strong education/public outreach and follow-up programs will help to engage the public and astronomical community. Swift has been selected by NASA for development and launch in 2003. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361620

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The International Gamma-Ray Astrophysics Laboratory INTEGRAL is dedicated to the fine spectroscopy, accurate imaging, and arcminute location of celestial gamma-ray sources in the energy range 15 keV to 10 MeV. Simultaneous monitoring of the GRB site in X rays and in the optical V-band will be provided by two on-board monitors. Gamma-ray bursts will be discovered both during routine program observations as serendipitous sources in the large FOVs and as high-resolution time histories from the spectrometer anticoincidence system, forming part of the interplanetary network of GRB detectors. The observational capabilities of INTEGRAL further include the dissemination of INTEGRAL GRB alerts and associated data to the science community at large in order to facilitate rapid follow-up observations of GRB error boxes for counterpart searches, afterglow observations, and subsequent investigations. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361621

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

ESA’s INTEGRAL high-energy observatory is scheduled for launch in 2001. INTEGRAL carries two gamma-ray instruments, optimized respectively for spectroscopy and high-resolution imaging, complemented by an X-ray and an optical monitor. The high sensitivity of the INTEGRAL instruments will allow the detection and detailed studies of relatively faint gamma-ray bursts. The INTEGRAL Burst Alert System (IBAS) is implemented as a ground-based system, working on the near-real time telemetry stream. It is expected that the system will detect more than one GRB per month in the field of view of the main instruments. Positions with an accuracy of a few arc-minutes will be distributed to the community for follow-up observations within a few tens of seconds of the event. Furthermore, the system will upload commands to optimize the detection of an associated transient with the INTEGRAL optical monitor. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361622

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

MAXI is an X-ray all-sky monitor mission which will be deployed on the Japanese Experiment Module of the International Space Station in 2004. It is designed to monitor X-ray sources by scanning the entire sky every 90 minutes, and can detect X-ray sources of 3 mCrab in one day. Although its instantaneous field of view is limited to narrow fan beams, one can expect ∼5 GRBs to occur in the field of view and ∼25 afterglows to be detected per year. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361623

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We are designing MARGIE as a 100 day ULDB mission to: a) detect and localize gamma-ray bursts; and b) survey the hard X-ray sky. MARGIE will consist of one small field-of-view (FOV) and four large FOV coded mask modules mounted on a balloon gondola. The burst position will be calculated onboard and disseminated in near-real time, while information about every count will be telemetered to the ground for further analysis. In a 100-day mission we will localize ∼40 bursts with peak photon fluxes from 0.14 to ∼5 ph cm−2&hthinsp;s−1using 1 s integrations; the typical localization resolution will be better than ∼2 arcminutes. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361624

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The first prototypes of innovative very wide field X-ray telescopes of Lobster-Eye type confirm the feasibility to develop such instruments for flight in the near future. These devices are expected to allow very wide field (more than 1000 square degrees) monitoring of the sky in X-rays (up to 10 keV and perhaps even more) with high sensitivity. We discuss the recent status of the development of very wide field X-ray telescopes as well as related scientific questions including expected major contributions such as monitoring and study of X-ray afterglows of Gamma Ray Bursts. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361625

出版商:AIP    

年代:1900

数据来源: AIP