Do long duration gamma ray bursts follow star formation?
Do long duration gamma ray bursts follow star formation?
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DOI：
10.1088/1475-7516/2007/07/003
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发表时间：
2007-01
影响因子：
6.4
通讯作者：
D. Guetta;T. Piran
中科院分区：
文献类型：
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作者：
D. Guetta;T. Piran
我们比较了从BATSE（突发和瞬态源实验）长爆发峰值流量分布推断的光度函数和速率与从斯威夫特峰值流量分布推断的光度函数和速率。我们发现，BATSE和雨燕峰通量可以用相同的光度函数拟合，并且这两个样本与遵循星星形成率的人口是相容的。估计的本地长伽玛暴速率（没有波束修正）变化了5倍，从0.05 Gpc−3 yr−1（对于有大部分高红移爆发的速率函数）到0.27 Gpc−3 yr−1（对于有许多本地爆发的速率函数）。然后我们将BeppoSax/HETE 2和Swift观测到的红移分布与光度函数的预测值进行了比较，发现BeppoSax/HETE 2和Swift观测到的红移分布之间的差异只能部分地由探测器的不同阈值来解释，这可能表明了强烈的选择效应。在尝试了不同形式的星星形成率（SFR）后，我们发现观测到的雨燕红移分布，观测到的高红移爆发比预期的要多，与简单地遵循当前SFR模型的GRB率不一致。我们表明，这可以解释GRB的演化超越SFR（更多的高红移爆发）。或者，如果光度函数演化，早期爆发更明亮，或者如果强选择效应影响红移的测定，也会出现这种情况。
We compare the luminosity function and rate inferred from the BATSE (Burst and Transient Source Experiment) long bursts peak flux distribution with those inferred from the Swift peak flux distribution. We find that the BATSE and the Swift peak fluxes can be fitted by the same luminosity function and the two samples are compatible with a population that follows the star formation rate. The estimated local long GRB rate (without beaming corrections) varies by a factor of five from 0.05 Gpc−3 yr−1 for a rate function that has a large fraction of high redshift bursts to 0.27 Gpc−3 yr−1 for a rate function that has many local ones. We then turn to comparing the BeppoSax/HETE2 and the Swift observed redshift distributions and compare them with the predictions of the luminosity function found. We find that the discrepancy between the BeppoSax/HETE2 and Swift observed redshift distributions is only partially explained by the different thresholds of the detectors and it may indicate strong selection effects. After trying different forms of the star formation rate (SFR) we find that the observed Swift redshift distribution, with more observed high redshift bursts than expected, is inconsistent with a GRB rate that simply follows current models for the SFR. We show that this can be explained by GRB evolution beyond the SFR (more high redshift bursts). Alternatively this can also arise if the luminosity function evolves and earlier bursts were more luminous or if strong selection effects affect the redshift determination.