Meli 2009 质子加速产生的超高能宇宙射线

主要内容:
一个模型

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Title:		Ultra high energy cosmic rays: subluminal and superluminal shocks
Authors:		Meli, A.; Becker, J. K.; Quenby, J. J
Publication:		eprint arXiv:0905.4466
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		4 pages, 4 figures, paper contribution for the International Cosmic Ray Conference 2009, Lodz Poland
Bibliographic Code:		2009arXiv0905.4466M

Abstract

Diffusive shock acceleration is invoked to explain non-thermal particle acceleration in Supernova Remnants, Active Galactic Nuclei (AGN) Jets, Gamma ray Bursts (GRBs) and various large scale cosmic structures. The importance of achieving the highest observed particle energies by such a mechanism in a given astrophysical situation is a recurring theme. In this work, shock acceleration in relativistic shocks is discussed, mostly focusing on a numerical study concerning proton acceleration efficiency by subluminal and superluminal shocks, emphasising on the dependence of the scattering model, bulk Lorentz factor and the angle between the magnetic field and the shock flow. We developed a diffuse cosmic ray model based on the study of different shock boost factors, which shows that spectra from AGN fit current observations of ultra high energy cosmic rays, above 5.7 x 10^10 GeV, much better than GRBs, indicating that AGN are the primary candidates to explain the UHECR flux. Recent Fermi observations of GRB090816c indicate very flat spectra which are expected within our model predictions and support evidence that GRB particle spectra can be flat, when the shock Lorentz factor is of order ~1000.

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Barkov 2009 数值模拟磁化冕吸积到旋转黑洞

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Title:		Accretion of a massive magnetized torus on a rotating black hole
Authors:		Barkov, Maxim V.; Baushev, Anton N.
Publication:		eprint arXiv:0905.4440
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		11 pages, 9 figures, submitted to MNRAS
Bibliographic Code:		2009arXiv0905.4440B

Abstract

We present numerical simulations of the axisymmetric accretion of a massive magnetized plasma torus on a rotating black hole. We use a realistic equation of state, which takes into account neutrino cooling and energy loss due to nucleus dissociations. We simulated various magnetic field configurations and torus models, both optically thick and thin for neutrinos. It is shown that the neutrino cooling does not significantly change either the structure of the accretion flow or the total energy release of the system. The calculations evidence heating of the wind surrounding the collapsar by the shock waves generated at the jet-wind border. This mechanism can give rise to a hot corona around the binary system like SS433. Angular momentum of the accreting matter defines the time scale of the accretion. Due to the absence of the magnetic dynamo in our calculations, the initial strength and topology of the magnetic field determines magnetization of the black hole, jet formation properties and the total energy yield. We estimated the total energy transformed to jets as $1.3\times 10^{52}$ {ergs} which was sufficient to explain hypernova explosions like GRB 980425 or GRB 030329.

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Moscibrodzka 2009 在磁化吸积中气体压的作用

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Title:		Magnetized Accretion Flows: Effects of Gas Pressure
Authors:		Moscibrodzka, Monika; Proga, Daniel
Publication:		eprint arXiv:0905.3920
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Galaxy Astrophysics
Comment:		17 pages, 7 figures, accepted for publication in MNRAS
Bibliographic Code:		2009arXiv0905.3920M

Abstract

We study how axisymmetric magnetohydrodynamical (MHD) accretion flows depend on gamma adiabatic index in the polytropic equation of state. This work is an extension of Moscibrodzka & Proga (2008), where we investigated the gamma dependence of 2-D Bondi-like accretion flows in the hydrodynamical (HD) limit. Our main goal is to study if simulations for various gamma can give us insights into to the problem of various modes of accretion observed in several types of accretion systems such as black hole binaries (BHB), active galactic nuclei (AGN), and gamma-ray bursts (GRBs). We find that for gamma >~ 4/3, the fast rotating flow forms a thick torus that is supported by rotation and gas pressure. As shown before for gamma=5/3, such a torus produces a strong, persistent bipolar outflow that can significantly reduce the polar funnel accretion of a slowly rotating flow. For low gamma, close to 1, the torus is thin and is supported by rotation. The thin torus produces an unsteady outflow which is too weak to propagate throughout the polar funnel inflow. Compared to their HD counterparts, the MHD simulations show that the magnetized torus can produce an outflow and does not exhibit regular oscillations. Generally, our simulations demonstrate how the torus thickness affects the outflow production. They also support the notion that the geometrical thickness of the torus correlates with the power of the torus outflow. Our results, applied to observations, suggest that the torus ability to radiatively cool and become thin can correspond to a suppression of a jet as observed in the BHB during a transition from a hard/low to soft/high spectral state and a transition from a quiescent to hard/low state in AGN.

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Moscibrodzka ，莫妮卡

Tejos 2009 伽玛暴余辉中的MgII吸收线

主要内容:
貌似镁线比想像的强

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Title:		Casting light on the 'anomalous' statistics of Mg II toward Gamma-Ray Burst afterglows: the incidence of weak systems
Authors:		Tejos, Nicolas; Lopez, Sebastian; Prochaska, J. Xavier; Bloom, Joshua S.; Chen, Hsiao-Wen; Dessauges-Zavadsky, Miroslava; Maureira, Maria J.
Publication:		eprint arXiv:0905.3768
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		17 pages, 3 tables, 3 figures, submitted to the ApJ
Bibliographic Code:		2009arXiv0905.3768T

Abstract

We revisit echelle spectra (spectral resolution R ~ 40000) of 8 Gamma-Ray Burst afterglows to obtain the incidence (dN/dz) of weak intervening Mg II systems at a mean redshift of = 1.5. We show that dN/dz of systems having restframe equivalent widths 0.07 A <> 1 A, where dN/dz toward GRBs has been found to be larger than toward QSOs by a factor of ~ 4. We confirm the overdensity albeit at a factor of ~ 3 only. This suggests that any explanation for the GRB/QSO discrepancy, be it intrinsic to the absorbers or a selection effect, should be inherent only to the galaxies that host strong absorbers in the line-of-sight to GRBs. We argue that, of all scenarios that have been proposed, lensing amplification is the one that could explain the strong Mg II enhancement while allowing for no significant enhancement in the weak absorbers.

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Samushia 2009 用伽玛暴限制暗能量

主要内容:
也是弄个不依赖于宇宙学参数的距离, 然后拟合参数.

但是伽玛暴比较远, 对应于宇宙早期, 那时候暗能量不重要, 不是对限制限制暗物质更有效些么?

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Title:		Constraining dark energy with gamma-ray bursts
Authors:		Samushia, Lado; Ratra, Bharat
Publication:		eprint arXiv:0905.3836
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		24 pages, 7 figures
Bibliographic Code:		2009arXiv0905.3836S

Abstract

We use the cosmology-independent gamma-ray burst (GRB) distances of Y. Wang (2008) to constrain dark energy cosmological model parameters. Current GRB data alone can not tightly constrain cosmological parameters and allow for a wide range of dark energy models. When used jointly with current Type Ia supernovae data and baryon acoustic peak measurements, the GRB data favor slightly lower values of nonrelativistic matter energy density. We show that with a future factor of 2 reduction in the GRB distance errors, GRBs can give very tight constraints on cosmological parameters.

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van Putten 2009 超高能辐射来自科尔黑洞的旋转能

主要内容:
文章号称解释这些高能粒子的辐射机制的, 但貌似没讲如何产生的这些高能粒子, 而只是说他们的能量来源于黑洞旋转能.

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Title:		Nonthermal transient phenomena around rotating black holes
Authors:		van Putten, Maurice H. P. M.
Publication:		eprint arXiv:0905.3367
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		Invited review, in Orleans School On The Sciences Of The Universe: Mass Motion (Springer-Verlag), to appear
Bibliographic Code:		2009arXiv0905.3367V

Abstract

Ultra-high energy cosmic rays (UHECRs) and gamma-ray bursts (GRBs) are the most exceptional nonthermal transient events, that appear to be associated with black holes. Here, we describe radiation mechanisms induced by turbulent flows around rapidly rotating black holes: high-energy emissions from a relativistic capillary effect along the black hole spin-axis and low-energy emissions by catalytic conversion of spin-energy. High-energy emissions arise, concurrently, in photons and, upstream of an outgoing Alfv\'en front, in ionic contaminants by linear acceleration. The latter develop into ultra-high energy cosmic rays (UHECRs) about the Greisen-Zatsepin-Kuzmin (GZK) threshold in low-luminosity, intermittent active galactic nuclei. These may include Seyfert galaxies and Cen A suggested by detections of UHECRs by the Pierre Auger Observatory and, for the latter, also of Very High Energy (VHE) gamma-rays by the High Energy Stereoscopic System (HESS). Nearly complete spin-down of stellar mass black holes is common to collapsars and mergers of neutron stars with another neutron star or companion black hole. Thus, long GRBs from rotating black holes explain events with and without supernovae and a diversity in their X-ray afterglows. Their intrinsic exponential decay is remarkably consistent with the average of 600 light curves of long GRBs, whose total output agrees with observed peak and true energies in gamma-rays. We conclude that long GRBs are spin-powered. Gravitational radiation from turbulent flows in SgrA* might be of interest to the planned Laser Interferometric Space Antenna (LISA) and, for stellar mass black holes in GRBs, should be detectable by LIGO-Virgo. Long GRBs from naked inner engines produced in mergers produce long-duration radio-burst that may be seen in all-sky surveys by the Low Frequency Array (LOFAR).

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Bogomazov 2009 磁星, 伽玛暴和双中子星

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Title:		Magnetars, Gamma-ray Bursts, and Very Close Binaries
Authors:		Bogomazov, A. I.; Popov, S. B.
Publication:		eprint arXiv:0905.3238
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Comment:		16 pages, 4 figures; Astronomy Reports, volume 53, no. 4, pp. 325-333 (2009)
Bibliographic Code:		2009arXiv0905.3238B

Abstract

We consider the possible existence of a common channel of evolution of binary systems, which results in a gamma-ray burst during the formation of a black hole or the birth of a magnetar during the formation of a neutron star. We assume that the rapid rotation of the core of a collapsing star can be explained by tidal synchronization in a very close binary. The calculated rate of formation of rapidly rotating neutron stars is qualitatively consistent with estimates of the formation rate of magnetars. However, our analysis of the binarity of newly-born compact objects with short rotational periods indicates that the fraction of binaries among them substantially exceeds the observational estimates. To bring this fraction into agreement with the statistics for magnetars, the additional velocity acquired by a magnetar during its formation must be primarily perpendicular to the orbital plane before the supernova explosion, and be large.

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Jenkins 2009 各星系的元素柱密度

主要内容:
166页的ApJ文章, 很强大.

主要内容大致是给出了ISM中各种元素如Mg,Cr等的柱密度. 而星系又有很多..., 所以可以列出很大一个表.

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Title:		A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
Authors:		Jenkins, Edward B.
Publication:		eprint arXiv:0905.3173
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - Galaxy Astrophysics
Comment:		166 pages, 21 figures, pages 116-166 contain detailed tabulations that may not be of interest to most readers. Accepted for publication in the Astrophysical Journal
Bibliographic Code:		2009arXiv0905.3173J

Abstract

A study of gas-phase element abundances reported in the literature for 17 different elements sampled over 243 sight lines in the local part of our Galaxy reveals that the depletions into solid form (dust grains) are extremely well characterized by trends that employ only three kinds of parameters. One is an index that describes the overall level of depletion applicable to the gas in any particular sight line, and the other two represent linear coefficients that describe how to derive each element's depletion from this sight-line parameter. The information from this study reveals the relative proportions of different elements that are incorporated into dust at different stages of grain growth. An extremely simple scheme is proposed for deriving the dust contents and metallicities of absorption-line systems that are seen in the spectra of distant quasars or the optical afterglows of gamma-ray bursts. Contrary to presently accepted thinking, the elements sulfur and krypton appear to show measurable changes in their depletions as the general levels of depletions of other elements increase, although more data are needed to ascertain whether or not these findings truly compelling. Nitrogen appears to show no such increase. The incorporation of oxygen into solid form in the densest gas regions far exceeds the amounts that can take the form of silicates or metallic oxides; this conclusion is based on differential measurements of depletion and thus is unaffected by uncertainties in the solar abundance reference scale.

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Schmidt 2009 伽玛暴的光度函数

主要内容:
用了E_p--V/V_max (variability)的统计关系, 然后得到E_p-L_iso的关系.

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From pictures

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Title:		Gamma-Ray Burst Luminosity Functions Based On a Newly Discovered Correlation Between Peak Spectral Energy and V/V_max
Authors:		Schmidt, Maarten
Publication:		eprint arXiv:0905.2968
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		32 pages, 13 figures, to be published in the Astrophysical Journal
Bibliographic Code:		2009arXiv0905.2968S

Abstract

We have discovered a correlation between the observed peak spectral energy E_pk,obs and the average Euclidean value of V/V_max of gamma-ray bursts (GRBs). We present the evidence for the correlation in the GUSBAD catalog and use it to derive the luminosity function of GRBs without using any redshifts. The procedure involves dividing GUSBAD GRBs in five spectral classes based on their E_pk,obs. The overall luminosity function is derived assuming that each of the spectral classes contributes a gaussian luminosity function. Their central luminosity is derived from the average observed Euclidean V/V_max. We explore various forms for the GRB rate function GR(z) in predicting redshift distributions of GRBs detected by Swift. We find that GR(z) peaks at a higher redshift than the typical star formation history currently favored in the literature. We consider two examples of GR(z) that successfully predict the observed redshift distribution of Swift GRBs. With the luminosity functions in hand, we convert the E_pk,obs-V/V_max correlation into an E_pk,obs-L_iso correlation and a rest frame E_pk-L_iso correlation. In comparing the E_pk-L_iso correlation with a published correlation based on GRBs with known E_pk,obs and redshifts, we discuss the effect of Malmquist bias.

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Kumar 2009 以GRB 080916C为例, 说高能谱可能来自于外激波的同步辐射

主要内容:
而prompt阶段的软伽玛射线和外激波的同步辐射的叠加导致了看到的Band 谱拟合.

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From pictures

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Title:		On the generation of high energy photons detected by the Fermi Satellite from gamma-ray bursts
Authors:		Kumar, Pawan; Barniol Duran, Rodolfo
Publication:		eprint arXiv:0905.2417
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		11 pages, 2 figures
Bibliographic Code:		2009arXiv0905.2417K

Abstract

Observations of gamma-ray bursts by the Fermi satellite, capable of detecting photons in a very broad energy band: 8keV to >300GeV, have opened a new window for the study of these enigmatic explosions. It is widely assumed that photons of energy larger than 100 MeV are produced by the same source that generated lower energy photons -- at least whenever the shape of the spectrum is a Band function. We report here a surprising discovery -- the Fermi data for a bright burst, GRB 080916C, unambiguously shows that the high energy photons (>= 100MeV) were generated in the external shock via the synchrotron process, and the lower energy photons had a distinctly different source. The magnetic field in the region where high energy photons were produced (and also the late time afterglow emission region) is found to be consistent with shock compressed magnetic field of the circum-stellar medium. This result sheds light on the important question of the origin of magnetic fields required for gamma-ray burst afterglows. The external shock model for high energy radiation makes a firm prediction that can be tested with existing and future observations.

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Granot 2009 一些Fermi高能的观测特征和080916C

主要内容:
写了一点大家正在关心一些关于高能的哪些热点问题: 可能的辐射机制有哪些, 延迟的辐射机制, 对罗仑兹因子的限制.

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Title:		GRB Theory in the Fermi Era
Authors:		Granot, Jonathan; Fermi LAT, for the; GBM collaborations
Publication:		eprint arXiv:0905.2206
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		8 pages, 1 figure with 3 panels - Invited talk, submitted to Proceedings of 44th Recontres de Moriond - "Very High Energy Phenomena in the Universe", La Thuile (Val d'Aosta, Italy) February 1 - 8, 2009
Bibliographic Code:		2009arXiv0905.2206G

Abstract

Before the launch of the Fermi Gamma-ray Space Telescope there were only a handful of gamma-ray bursts (GRBs) detected at high energies (above 100 MeV), while several different suggestions have been made for possible high-energy emission sites and mechanisms. Here I briefly review some of the theoretical expectations for high-energy emission from GRBs, outline some of the hopes for improving our understanding of GRB physics through Fermi observations of the prompt GRB emission or the early afterglow (first few hours after the GRB), and summarize what we have learned so far from the existing Fermi GRB observations (over its first half-year of operation). Highlights include the first detection of > GeV emission from a short GRB, as well as detailed temporal and spectral information for the first GRB with > GeV emission and a measured redshift, that has the highest measured apparent (isotropic equivalent) radiated energy output (for any GRB), the largest lower limit on the bulk Lorentz factor of the emitting region, and constrains possible Lorentz invariance violation by placing a robust lower limit on the quantum gravity mass.

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Nomoto 2009 第一代星和Ib型超新星的联系

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Title:		First Stars Type Ib Supernovae Connection
Authors:		Nomoto, Ken'ichi; Tanaka, Masaomi; Kamiya, Yasuomi; Tominaga, Nozomu; Maeda, Keiichi
Publication:		Low-Metallicity Star Formation: From the First Stars to Dwarf Galaxies, Proceedings of the International Astronomical Union, IAU Symposium, Volume 255, p. 182-188
Publication Date:		12/2008
Origin:		CUP
Keywords:		Galaxy: halo, gamma rays: bursts, nuclear reactions, nucleosynthesis, abundances, stars: abundances, stars: Population II, supernovae: general
Abstract Copyright:		(c) 2008: Copyright © International Astronomical Union 2008
DOI:		10.1017/S1743921308024794
Bibliographic Code:		2008IAUS..255..182N

Abstract

The very peculiar abundance patterns observed in extremely metal-poor (EMP) stars can not be explained by conventional normal supernova nucleosynthesis but can be well-reproduced by nucleosynthesis in hyper-energetic and hyper-aspherical explosions, i.e., Hypernovae (HNe). Previously, such HNe have been observed only as Type Ic supernovae. Here, we examine the properties of recent Type Ib supernovae (SNe Ib). In particular, SN Ib 2008D associated with the luminous X-ray transient 080109 is found to be a more energetic explosion than normal core-collapse supernovae. We estimate that the progenitor's main sequence mass is M_MS = 20 ‑ 25M_ȯ with an explosion of kinetic energy of E_K ~ 6.0 × 10⁵¹ erg. These properties are intermediate between those of normal SNe and hypernovae associated with gamma-ray bursts. Therefore, such energetic SNe Ib could also make an important contribution to the chemical enrichment in the early Universe.

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Harikae 2009 狭义相对论下的慢旋转坍缩星MHD模拟

主要内容:
存在一个critical角动量, 低于那个值, 就不能形成吸积盘, 物质都直接掉到黑洞(这时候不是也有能量释放的吗?).

不过这个模拟还是存在能量没观测要求那么多的问题.

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Title:		Long-Term Evolution of Slowly Rotating Collapsar in Special Relativistic Magnetohydrodynamics
Authors:		Harikae, Seiji.; Takiwaki, Tomoya.; Kotake, Kei.
Publication:		eprint arXiv:0905.2006
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		44 pages with 17 figures
Bibliographic Code:		2009arXiv0905.2006H

Abstract

We present our numerical results of two-dimensional magnetohydrodynamic (MHD) simulations of the collapse of rotating massive stars in light of the collapsar model of gamma-ray bursts (GRBs). Pushed by recent evolution calculations of GRB progenitors, we focus on lower angular momentum of the central core than the ones taken mostly in previous studies. By performing special relativistic simulations including both realistic equation of state and neutrino coolings, we follow a unprecedentedly long-term evolution of the slowly rotating collapsars up to $\sim$ 10 s, accompanied by the formation of jets and accretion disks. Our results show that for the GRB progenitors to function as collapsars, there is a critical initial angular momentum, below which matter is quickly swallowed to the central objects, no accretion disks and no MHD outflows are formed. When larger than the criteria, we find the launch of the MHD jets in the following two ways. For models with stronger initial magnetic fields, the magnetic pressure amplified inside the accretion disk can drive the MHD outflows, which makes the strong magnetic explosions like a 'magnetic tower' (type II). For the models with weaker initial magnetic fields, the magnetic tower stalls first and the subsequent MHD outflows are produced by some eventual inflows of the accreting material from the equator to the polar regions (type I). Regardless of type I or II, the jets can attain only mildly relativistic speeds with the explosion energy less than $10^{49} \erg$, which could possibly be related to the X-ray flashes. Due to high opacity for neutrinos inside the disk, we find that the luminosities of $\nu_e$ and $\bar{\nu}_e$ become almost comparable, which is advantageous for making the energy deposition rate larger.

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Kocevski 2009 伽玛暴宿主星系的质量分布

主要内容:
看伽玛暴是否和恒星形成一致.

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Title:		Modeling The GRB Host Galaxy Mass Distribution: Are GRBs Unbiased Tracers of Star Formation?
Authors:		Kocevski, Daniel; West, Andrew A.; Modjaz, Maryam
Publication:		eprint arXiv:0905.1953
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		11 pages, 9 figures, submitted to ApJ on Feb 5th, 2009
Bibliographic Code:		2009arXiv0905.1953K

Abstract

We model the mass distribution of long gamma-ray burst (GRB) host galaxies given recent results suggesting that GRBs occur in low metallicity environments. By utilizing measurements of the redshift evolution of the mass-metallicity (M-Z) relationship for galaxies, along with a sharp host metallicity cut-off suggested by Modjaz and collaborators, we estimate an upper limit on the stellar mass of a galaxy that can efficiently produce a GRB as a function of redshift. By employing consistent abundance indicators, we find that sub-solar metallicity cut-offs effectively limit GRBs to low stellar mass spirals and dwarf galaxies at low redshift. At higher redshifts, as the average metallicity of galaxies in the Universe falls, the mass range of galaxies capable of hosting a GRB broadens, with an upper bound approaching the mass of even the largest spiral galaxies. We compare these predicted limits to the growing number of published GRB host masses and find that extremely low metallicity cut-offs of 0.1 to 0.5 solar are effectively ruled out by a large number of intermediate mass galaxies at low redshift. A mass function that includes a smooth decrease in the efficiency of producing GRBs in galaxies of metallicity above 12+log(O/H)_(KK04) ~ 8.7 can, however, accommodate a majority of the measured host galaxy masses. We find that at z ~ 1, the peak in the observed GRB host mass distribution is inconsistent with the expected peak in the mass of galaxies harboring most of the star formation. This suggests that GRBs are metallicity biased tracers of star formation at low and intermediate redshifts, although our model predicts that this bias should disappear at higher redshifts due to the evolving metallicity content of the universe.

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