Imerito 2008 用将来的EXIST观测低光度的暴

主要内容:


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.4044)

· References in the Article

·

· Translate This Page

Title:		Probing the low-luminosity GRB population with new generation satellite detectors
Authors:		Imerito, A.; Coward, D.; Burman, R.; Blair, D.
Publication:		eprint arXiv:0808.4044
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		6 pages, 4 figures, accepted by MNRAS
Bibliographic Code:		2008arXiv0808.4044I

Abstract

We compare the detection rates and redshift distributions of low-luminosity (LL) GRBs localized by Swift with those expected to be observed by the new generation satellite detectors on GLAST (now Fermi) and, in future, EXIST. Although the GLAST burst telescope will be less sensitive than Swift's in the 15--150 keV band, its large field-of-view implies that it will double Swift's detection rate of LL bursts. We show that Swift, GLAST and EXIST should detect about 1, 2 & 30 LL GRBs, respectively, over a 5-year operational period. The burst telescope on EXIST should detect LL GRBs at a rate of more than an order of magnitude greater than that of Swift's BAT. We show that the detection horizon for LL GRBs will be extended from $z \simeq 0.4$ for Swift to $z \simeq 1.1$ in the EXIST era. Also, the contribution of LL bursts to the observed GRB redshift distribution will contribute to an identifiable feature in the distribution at $z \simeq 1$.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Nishikawa 2008 相对论喷流的辐射

主要内容:


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3781)

· References in the Article

·

· Translate This Page

Title:		Radiation from relativistic jets
Authors:		Nishikawa, K. -I.; Mizuno, Y.; Hardee, P.; Sol, H.; Medvedev, M.; Zhang, B.; Nordlund, A.; Frederiksen, J. T.; Fishman, G. J.; Preece, R.
Publication:		eprint arXiv:0808.3781
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		8 pages,3 figures, accepted for the Proceedings of Science of the Workshop on Blazar Variability across the Electromagnetic Spectrum, April 22 to 25, 2008
Bibliographic Code:		2008arXiv0808.3781N

Abstract

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability create collisionless shocks, which are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The ``jitter'' radiation from deflected electrons in small-scale magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation, a case of diffusive synchrotron radiation, may be important to understand the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Daskin 2008 用超新星和伽玛暴的空间分布来限制他们的前身星质量

主要内容:
是在星系里的空间分布（而不是天球上的方位角）

精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3766)

· References in the Article

·

· Translate This Page

Title:		Using Spatial Distributions to Constrain Progenitors of Supernovae and Gamma Ray Bursts
Authors:		Raskin, Cody; Scannapieco, Evan; Rhoads, James; Della Valle, Massimo
Publication:		eprint arXiv:0808.3766
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		18 pages, 19 figures, ApJ, in press
Bibliographic Code:		2008arXiv0808.3766R

Abstract

We carry out a comprehensive theoretical examination of the relationship between the spatial distribution of optical transients and the properties of their progenitor stars. By constructing analytic models of star-forming galaxies and the evolution of stellar populations within them, we are able to place constraints on candidate progenitors for core-collapse supernovae (SNe), long-duration gamma ray bursts, and supernovae Ia. In particular we first construct models of spiral galaxies that reproduce observations of core-collapse SNe, and we use these models to constrain the minimum mass for SNe Ic progenitors to approximately 25 solar masses. Secondly, we lay out the parameters of a dwarf irregular galaxy model, which we use to show that the progenitors of long-duration gamma-ray bursts are likely to have masses above approximately 43 solar masses. Finally, we introduce a new method for constraining the time scale associated with SNe Ia and apply it to our spiral galaxy models to show how observations can better be analyzed to discriminate between the leading progenitor models for these objects.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Zhang 2008 曲率效应可能产生非幂律谱

主要内容:


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3793)

· References in the Article

·

· Translate This Page

Title:		Curvature Effect of a Non-Power-Law Spectrum and Spectral Evolution of GRB X-Ray Tails
Authors:		Zhang, Bin-Bin; Zhang, Bing; Liang, En-Wei; Wang, Xiang-Yu
Publication:		eprint arXiv:0808.3793
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		12 pages, 4 figures, 1 table
Bibliographic Code:		2008arXiv0808.3793Z

Abstract

The apparent spectral evolution observed in the steep decay phase of many GRB early afterglows raises a great concern of the high-latitude ``curvature effect'' interpretation of this phase. However, previous curvature effect models only invoked a simple power law spectrum upon the cessation of the prompt internal emission. We investigate a model that invokes the ``curvature effect'' of a more general non-power-law spectrum and test this model with the Swift/XRT data of some GRBs. By comparing the simulated lightcurves/spectra with the observed ones, we show that one can reproduce both the observed lightcurve and the apparent spectral evolution of several GRBs using a model invoking a cut-off power-law spectrum. GRB 050814 is presented as an example. This suggests that at least for some GRBs, the fast spectral evolution in the steep-decay phase can be explained by the curvature effect invoking a non-power-law spectrum.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Hu 2008 XRO 080109/SN 2008D的MHD+shock breakout模型

主要内容:


精彩摘抄:
We propose to attribute the "non-thermal spectrum" observed to be a superposition of different thermal spectra produced at different layers of the stellar envelope.

文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3905)

· References in the Article

·

· Translate This Page

Title:		Rebound Shock Breakouts of Exploding Massive Stars: A MHD Void Model
Authors:		Hu, Ren-Yu; Lou, Yu-Qing
Publication:		eprint arXiv:0808.3905
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		4 pages, 1 figure, to appear in the proceedings of Nanjing 2008 GRB Conference, Nanjing, China, 23-27 June 2008
Bibliographic Code:		2008arXiv0808.3905H

Abstract

With a self-similar magnetohydrodynamic (MHD) model of an exploding progenitor star and an outgoing rebound shock and with the thermal bremsstrahlung as the major radiation mechanism in X-ray bands, we reproduce the early X-ray light curve observed for the recent event of XRO 080109/SN 2008D association. The X-ray light curve consists of a fast rise, as the shock travels into the "visible layer" in the stellar envelope, and a subsequent power-law decay, as the plasma cools in a self-similar evolution. The observed spectral softening is naturally expected in our rebound MHD shock scenario. We propose to attribute the "non-thermal spectrum" observed to be a superposition of different thermal spectra produced at different layers of the stellar envelope.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Yujin 2008 Suzaku对SGR 1900+14和SGR 1806-20的观测

主要内容:
包含一些数据，主要是谱。

精彩摘抄:


文章信息:

arXiv:0808.3846 [ps, pdf, other]

Title: Suzaku Observations of SGR 1900+14 and SGR 1806-20

Authors: Yujin E. Nakagawa, Tatehiro Mihara, Atsumasa Yoshida, Kazutaka Yamaoka, Satoshi Sugita, Toshio Murakami, Daisuke Yonetoku, Motoko Suzuki, Motoki Nakajima, Makoto Tashiro, Kazuhiro Nakazawa

Comments: 8 pages, 3 figures, Accepted for publication in PASJ (Suzaku 3rd special issue)

Subjects: Astrophysics (astro-ph)

Spectral and timing studies of Suzaku ToO observations of two SGRs, 1900+14 and 1806-20, are presented. The X-ray quiescent emission spectra were well fitted by a two blackbody function or a blackbody plus a power law model. The non-thermal hard component discovered by INTEGRAL was detected by the PIN diodes and its spectrum was reproduced by the power law model reported by INTEGRAL. The XIS detected periodicity P = 5.1998+/-0.0002 s for SGR 1900+14 and P = 7.6022+/-0.0007 s for SGR 1806-20. The pulsed fraction was related to the burst activity for SGR 1900+14.

Hirschi 2008 早期宇宙的恒星演化

主要内容:
也就是第一代恒星。
大于60Msun的可能在红巨星支损失足够多的质量而形成伽玛暴。

精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3723)

· References in the Article

·

· Translate This Page

Title:		Stellar Evolution in the Early Universe
Authors:		Hirschi, R.; Frischknecht, U.; Thielemann, F. -K.; Pignatari, M.; Chiappini, C.; Ekstroem, S.; Meynet, G.; Maeder, A.
Publication:		eprint arXiv:0808.3723
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		8 pages, 4 figures, proceedings of IAU Symposium 255, "Low-Metallicity Star Formation: From the First stars to Dwarf Galaxies", L.K. Hunt, S. Madden & R. Schneider, eds
Bibliographic Code:		2008arXiv0808.3723H

Abstract

Massive stars played a key role in the early evolution of the Universe. They formed with the first halos and started the re-ionisation. It is therefore very important to understand their evolution. In this paper, we describe the strong impact of rotation induced mixing and mass loss at very low $Z$. The strong mixing leads to a significant production of primary nitrogen 14, carbon 13 and neon 22. Mass loss during the red supergiant stage allows the production of Wolf-Rayet stars, type Ib,c supernovae and possibly gamma-ray bursts (GRBs) down to almost Z=0 for stars more massive than 60 solar masses. Galactic chemical evolution models calculated with models of rotating stars better reproduce the early evolution of N/O, C/O and C12/C13. We calculated the weak s-process production induced by the primary neon 22 and obtain overproduction factors (relative to the initial composition, Z=1.e-6) between 100-1000 in the mass range 60-90.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

GRB feed

Loading...

GRB feed

Loading...

von Kienlin 2008 一个新的软伽玛重复暴 SGR 0501+4516

主要内容:
New Soft Gamma Repeater 0501+4516 (GRB 080822): GLAST Burst Monitor detection
还是被GLAST的GBM看到的. 开始还被当成了 GRB 080822

精彩摘抄:


文章信息:

TITLE:   GCN CIRCULAR
NUMBER:  8122
SUBJECT: New Soft Gamma Repeater 0501+4516 (GRB 080822): GLAST Burst Monitor detection
DATE:    08/08/23 10:01:50 GMT
FROM:    Andreas von Kienlin at MPE  

Andreas von Kienlin (MPE), N.P. Bhat (UAH), E. Bissaldi (MPE),
M.S. Briggs (UAH), V. Connaughton (UAH), R. Diehl (MPE),
G.J. Fishman (NASA/MSFC), L. Gibby (NASA/MSFC), J. Greiner (MPE),
A.S. Hoover (LANL), A.J. van der Horst (NASA/ORAU), R.M. Kippen (LANL),
C. Kouveliotou (NASA/MSFC), G.G. Lichti (MPE), C.A. Meegan (NASA/MSFC),
S. McBreen (MPE), W.S. Paciesas (UAH), R.D. Preece (UAH), H. Steinle (MPE),
M.S. Wallace (LANL), and C.A. Wilson-Hodge (NASA/MSFC)report:

"At 12:41:59  UT on 2008 Aug 22, the GLAST Burst Monitor (GBM) triggered
on the new Soft Gamma Repeater 0501+4516 (GRB 080822)
(GBM 080822.529 / trigger 241101720), reported by SWIFT
(Holland et al., GCN Circ. 8112, Barthelmy et al, GCN Circ. 8113
and GCN Circ. 8119).

The on-ground calculated location, using the GBM trigger data, is
RA = 86.2, Dec = +43.5 (J2000 degrees),(equivalent to J2000 05h 45m, +43d
30'),
with an uncertainty of 3.3 degrees (radius, 1-sigma containment, statistical

only). The true location error is 8.0 degrees for this soft, short event.

This event has a duration of about 80 ms. The spectrum in the
10 keV to 100 keV energy band is well fit by a power law function
with an index of -1.6 +/-0.1. The high temperature for an
optically thin thermal bremsstrahlung (OTTB) fit is: 71 +/-13 keV. 
These results are consistent with the trigger clearly being seen to 100 keV.

The spectral analysis results presented above are preliminary."

Ramiez-Ruiz 2008 伽玛暴余辉的动力学数值模拟

主要内容:


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3448)

· References in the Article

·

· Translate This Page

Title:		The Hydrodynamics of Gamma-Ray Burst Remnants
Authors:		Ramirez-Ruiz, Enrico; MacFadyen, Andrew I.
Publication:		eprint arXiv:0808.3448
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		10 pages, 12 figures, emulateapj style, submitted to ApJ
Bibliographic Code:		2008arXiv0808.3448R

Abstract

This paper reports on the results of a numerical investigation designed to address how the initially anisotropic appearance of a GRB remnant is modified by the character of the circumburst medium and by the possible presence of an accompanying supernova (SN). Axisymmetric hydrodynamical calculations of light, impulsive jets propagating in both uniform and inhomogeneous external media are presented, which show that the resulting dynamics of their remnants since the onset of the non-relativistic phase is different from the standard self-similar solutions. Because massive star progenitors are expected to have their close-in surroundings modified by the progenitor winds, we consider both free winds and shocked winds as possible external media for GRB remnant evolution. Abundant confirmation is provided here of the important notion that the morphology and visibility of GRB remnants are determined largely by their circumstellar environments. For this reason, their detectability is highly biased in favor of those with massive star progenitors; although, in this class of models, the beamed component may be difficult to identify because the GRB ejecta is eventually swept up by the accompanying SN. The number density of asymmetric GRB remnants in the local Universe could be, however, far larger if they expand in a tenuous interstellar medium, as expected for some short GRB progenitor models. In these sources, the late size of the observable, asymmetric remnant could extend over a wide, possibly resolvable angle and may be easier to constrain directly.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Cao 2008 各向同性坍缩星自相似解

主要内容:


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3523)

· References in the Article

·

· Translate This Page

Title:		Homologous Core Collapse in a Massive Star and Self-Similar Evolution of Rebound Shocks
Authors:		Cao, Yi; Lou, Yu-Qing
Publication:		eprint arXiv:0808.3523
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		4 pages. To appear in the proceedings of "2008 Nanjing GRB conference", Nanjing, 23-27 June 2008
Bibliographic Code:		2008arXiv0808.3523C

Abstract

During the gravitational core collapse of a massive progenitor star which may give rise to at least a class of gamma-ray bursts (GRBs) associated with supernovae, a stellar core rapidly passes through a short yet important phase of neutronization, producing a huge amount of energetic neutrinos and photons which contribute to the total pressure within the progenitor core. The collection of neutrinos, photons and gas materials together may be approximated as a fluid with a polytropic index $\gamma=4/3$ under the action of self-gravity. With a substantial generalization and using analytical and numerical methods (Lou & Cao 2008), we recently constructed and examined various self-similar solutions to describe collapses, rebound shocks and flows systematically in a $\gamma=4/3$ polytropic gas mixture with spherical symmetry, and compare our results with those of Goldreich & Weber (1980). It is also possible to construct central void solutions without or with shocks. Various features and characteristics of this nonlinear relativistically hot gas dynamics, including asymptotic and exact solutions, are presented. This more general polytropic model analysis provides the dynamic basis of understanding the evolution of rebound shocks in supernovae (SNs) and the results may be also utilized to benchmark hydrodynamic simulations.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

O'Brien 2008 X-射线余辉

主要内容:
小综述

精彩摘抄:
GRB 060729的光变
谱指数

文章信息:

· arXiv e-print (arXiv:0808.3492)

· References in the Article

·

· Translate This Page

Title:		X-Ray Afterglows
Authors:		O'Brien, Paul; Willingale, Richard
Publication:		eprint arXiv:0808.3492
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		6 pages, 6 figures. To appear in: 2008 Nanjing GRB Conference, AIP, Eds. Y.F. Huang, Z.G. Dai, B. Zhang
Bibliographic Code:		2008arXiv0808.3492O

Abstract

We summarise the X-ray temporal and spectral variability properties of GRBs as observed using the Swift satellite. Despite much individual complexity, the flux and spectral variability can be reasonably well described by a combination of two components - which we denote as the prompt and the afterglow. The first, prompt component consists of the burst and its initial decay while the second, afterglow component fits the X-ray plateau phase and subsequent decline observed in the majority of GRBs. When strong spectral variability occurs it is associated with the prompt component while the X-ray plateau and later emission shows little if any spectral variability. We briefly compare the observations with some of the proposed models. Any model for the early or late emission must explain the differences in both temporal and spectral behaviour.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Gehrels 2008 暴本身和余辉的流量统计

主要内容:
包含一些暴的数据，包括：


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3391)

· References in the Article

·

· Translate This Page

Title:		Correlations of Prompt and Afterglow Emission in Swift Long and Short Gamma Ray Bursts
Authors:		Gehrels, N.; Barthelmy, S. D.; Burrows, D. N.; Cannizzo, J. K.; Chincarini, G.; Fenimore, E.; Kouveliotou, C.; O'Brien, P.; Palmer, D. M.; Racusin, J.; Roming, P. W. A.; Sakamoto, T.; Tueller, J.; Wijers, R. A. M. J.; Zhang, B.
Publication:		eprint arXiv:0808.3391
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		13 pages, 3 figures, 4 tables; to appear in the Astrophysical Journal, Dec 20, 2008, v. 689, no. 2
Bibliographic Code:		2008arXiv0808.3391G

Abstract

Correlation studies of prompt and afterglow emissions from gamma-ray bursts (GRBs) between different spectral bands has been difficult to do in the past because few bursts had comprehensive and intercomparable afterglow measurements. In this paper we present a large and uniform data set for correlation analysis based on bursts detected by the Swift mission. For the first time, short and long bursts can be analyzed and compared. It is found for both classes that the optical, X-ray and gamma-ray emissions are linearly correlated, but with a large spread about the correlation line; stronger bursts tend to have brighter afterglows, and bursts with brighter X-ray afterglow tend to have brighter optical afterglow. Short bursts are, on average, weaker in both prompt and afterglow emissions. No short bursts are seen with extremely low optical to X-ray ratio as occurs for "dark" long bursts. Although statistics are still poor for short bursts, there is no evidence yet for a subgroup of short bursts with high extinction as there is for long bursts. Long bursts are detected in the dark category at the same fraction as for pre-Swift bursts. Interesting cases are discovered of long bursts that are detected in the optical, and yet have low enough optical to X-ray ratio to be classified as dark. For the prompt emission, short and long bursts have different average tracks on flux vs fluence plots. In Swift, GRB detections tend to be fluence limited for short bursts and flux limited for long events.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Kann 2008 光学余辉是否能用于区分I，II型暴

主要内容:


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3221)

· References in the Article

·

· Translate This Page

Title:		Can optical afterglows be used to discriminate between Type I and Type II GRBs?
Authors:		Kann, D. A.
Publication:		eprint arXiv:0808.3221
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		7 Pages, 2 figures, to be published in the "2008 Nanjing GRB Conference" conference proceedings, figures have been downsampled
Bibliographic Code:		2008arXiv0808.3221K

Abstract

The precise localization of short/hard (Type I) gamma-ray bursts (GRBs) in recent years has answered many questions but raised even more. I present some results of a systematic study of the optical afterglows of long/soft (Type II) and short/hard (Type I) GRBs, focusing on the optical luminosity as another puzzle piece in the classification of GRBs.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Kuznetsov 2008 伽玛暴和余辉的时间-光子能量关系

主要内容:


精彩摘抄:
就是能量越高，持续时间越短

文章信息:

· Find Similar Abstracts (with default settings below)

· Electronic On-line Article (HTML)

· arXiv e-print (arXiv:0808.3376)

· References in the Article

·

· Translate This Page

Title:		United classification of cosmic gamma-ray bursts and their counterparts
Authors:		Kuznetsov, Alexander
Publication:		eprint arXiv:0808.3376
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		Keywords Gamma rays: bursts; Astrophys Space Sci (2008) 314: 311-318; doi:10.1007/s10509-008-9770-2
Bibliographic Code:		2008arXiv0808.3376K

Abstract

United classification of gamma-ray bursts and their counterparts is established on the basis of measured characteristics: photon energy E and emission duration T. The founded interrelation between the mentioned characteristics of events consists in that, as the energy increases, the duration decreases (and vice versa). The given interrelation reflects the nature of the phenomenon and forms the E-T diagram, which represents a natural classification of all observed events in the energy range from 10E9 to 10E-6 eV and in the corresponding interval of durations from about 10E-2 up to 10E8 s. The proposed classification results in the consequences, which are principal for the theory and practical study of the phenomenon.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Petkov 2008 寻找原初黑洞蒸发形成的伽玛暴

主要内容:


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.3093)

· References in the Article

·

· Translate This Page

Title:		Searching for Very-High-Energy Gamma-Ray Bursts from Evaporating Primordial Black Holes
Authors:		Petkov, V. B.; Bugaev, E. V.; Klimai, P. A.; Andreev, M. V.; Volchenko, V. I.; Volchenko, G. V.; Gaponenko, A. N.; Guliev, Zh. Sh.; Dzaparova, I. M.; Smirnov, D. V.; Sergeev, A. V.; Chernyaev, A. B.; Yanin, A. F.
Publication:		eprint arXiv:0808.3093
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		6 pages, 6 figures; Astron.Lett.34:509-514,2008, Pisma Astron.Zh.34:563-569,2008; doi:10.1134/S106377370808001X
Bibliographic Code:		2008arXiv0808.3093P

Abstract

Temporal and energy characteristics of the very-high-energy gamma-ray bursts from evaporating primordial black holes have been calculated by assuming that the photospheric and chromospheric effects are negligible. The technique of searching for such bursts on shower arrays is described. We show that the burst time profile and the array dead time should be taken into account to interpret experimental data. Based on data from the Andyrchy array of the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences), we have obtained an upper limit on the number density of evaporating primordial black holes in a local region of space with a scale size of ~10^{-3} pc. Comparison with the results of previous experiments is made.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Savaglio 2008 低质量和低金属丰度的宿主星系

主要内容:


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.2917)

· References in the Article

·

· Translate This Page

Title:		Low-Mass and Metal-Poor Gamma-Ray Burst Host Galaxies
Authors:		Savaglio, Sandra
Publication:		eprint arXiv:0808.2917
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		Invited contribution, to appear in proceedings of IAU Symposium 255: "Low-Metal licity Star Formation: From the First Stars to Dwarf Galaxies", Rapallo June 2008, L.K. Hunt, S. Madden & R. Schneider, eds
Bibliographic Code:		2008arXiv0808.2917S

Abstract

Gamma-ray bursts (GRBs) are cosmologically distributed, very energetic and very transient sources detected in the gamma-ray domain. The identification of their x-ray and optical afterglows allowed so far the redshift measurement of 150 events, from z = 0.01 to z = 6.29. For about half of them, we have some knowledge of the properties of the parent galaxy. At high redshift (z > 2), absorption lines in the afterglow spectra give information on the cold interstellar medium in the host. At low redshift (z <> Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Liang 2008 42个暴来定宇宙学参数

主要内容:


精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0808.2655)

· References in the Article

·

· Translate This Page

Title:		Cosmology-Independent Distance Moduli of 42 Gamma-Ray Bursts between Redshift of 1.44 and 6.60
Authors:		Liang, Nan; Zhang, Shuang Nan
Publication:		eprint arXiv:0808.2655
Publication Date:		08/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		5 pages, 2 figures, 3 tables. To appear in the proceedings of "2008 Nanjing GRB conference", Nanjing, 23-27 June 2008
Bibliographic Code:		2008arXiv0808.2655L

Abstract

This report is an update and extension of our paper accepted for publication in ApJ (arXiv:0802.4262). Since objects at the same redshift should have the same luminosity distance and the distance moduli of type Ia supernovae (SNe Ia) obtained directly from observations are completely cosmology independent, we obtain the distance modulus of a gamma-ray burst (GRB) at a given redshift by interpolating or iterating from the Hubble diagram of SNe Ia. Then we calibrate five GRB relations without assuming a particular cosmological model, from different regression methods, and construct the GRB Hubble diagram to constrain cosmological parameters. Based upon these relations we list the cosmology-independent distance moduli of 42 GRBs between redshift of 1.44 and 6.60, with the 1-$\sigma$ uncertainties of 1-3%.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)