arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2602.03032astro-ph.HE
收藏

距离如何影响GRB瞬时辐射测量

How Distance Affects GRB Prompt Emission Measurements

Astrophysics Science Division, NASA Goddard Space Flight Center(NASA戈达德太空飞行中心天体物理学科学部);University of Tampa(坦帕大学);Joint Space-Science Institute, University of Maryland(马里兰大学联合空间科学研究所);The Department of Physics, The George Washington University(乔治华盛顿大学物理系)

Michael J. Moss, Amy Y. Lien, S. Bradley Cenko, Sylvain Guiriec, Craig B. Markwardt

AI总结:

研究探讨了Gamma-Ray Burst (GRB)瞬时辐射测量如何受到源距离增加的影响,通过模拟高红移GRB的观测结果,发现低信噪比导致的背景主导效应使测量的持续时间低估,且高红移GRB的平均持续时间和能量变化与'冰山尖端'效应一致。

摘要:

我们研究了Gamma-Ray Burst (GRB)瞬时辐射测量如何受到源距离增加的影响。我们选取了26个红移z<1的明亮GRB,由Swift卫星上的 Burst Alert Telescope (BAT)观测,并模拟了如果GRB位于更高红移时BAT会观测到的结果。我们使用贝叶斯块方法测量了模拟的伽马射线信号的持续时间,并计算了封装的流量和峰值流量。正如预期的那样,我们发现几乎所有模拟高红移GRB的持续时间(流量)测量值都比其真实持续时间(能量)短,这是因为低信噪比的辐射完全被背景主导,即所谓的'冰山尖端'效应。这种效应强烈依赖于源光曲线的轮廓和强度。由于GRB光曲线的特殊性,测量的持续时间随红移变化没有共同的行为。我们将我们的合成高红移(即z>3)GRB与72个观测到的高红移爆发样本进行了比较,发现这两个样本并不与来自同一潜在种群不一致。我们得出结论:(i)由Swift/BAT观测的高红移GRB的瞬时辐射持续时间(流量)最可能是低估,有时低估幅度为几十倍(约2倍);(ii)随着红移增加,平均GRB瞬时辐射持续时间和流量的变化与'冰山尖端'效应一致。

英文摘要:

We investigated how Gamma-Ray Burst (GRB) prompt emission measurements are affected by increasing distance to the source. We selected a sample of 26 bright GRBs with measured redshifts $z<1$ observed by the Burst Alert Telescope (BAT) on board the Neil Gehrels Swift Observatory (Swift) and simulated what BAT would have observed if the GRBs were at larger redshifts. We measured the durations of the simulated gamma-ray signals using a Bayesian block approach and calculated the enclosed fluences and peak fluxes. As expected, we found that almost all durations (fluences) measured for simulated high-$z$ GRBs were shorter (less) than their true durations (energies) due to low signal-to-noise ratio emission becoming completely dominated by background, i.e., the ``tip-of-the-iceberg'' effect. This effect strongly depends on the profile and intensity of the source light curve. Due to the uniqueness of GRB light curves, there is no common behavior in the evolution of measured durations with redshift. We compared our synthetic high-$z$ (i.e., $z>3$) GRBs to a sample of 72 observed high-$z$ bursts and found that the two samples were not inconsistent with being drawn from the same underlying population. We conclude that: (i) prompt emission durations (fluences) of high-$z$ GRBs observed by Swift/BAT are most likely underestimations, sometimes by factors of $\sim$several tens ($\sim2$), and (ii) changes in the average GRB prompt emission duration and fluence with increasing redshift are consistent with the tip-of-the-iceberg effect.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑