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arXiv 2409.01644astro-ph.HE
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伽马射线暴变率-光度关系的新结果

New results on the gamma-ray burst variability-luminosity relation

C. Guidorzi, R. Maccary, A. Tsvetkova, S. Kobayashi, L. Amati, L. Bazzanini, M. Bulla, A. E. Camisasca, L. Ferro, D. Frederiks, F. Frontera, A. Lysenko, M. Mais… 展开作者

C. Guidorzi, R. Maccary, A. Tsvetkova, S. Kobayashi, L. Amati, L. Bazzanini, M. Bulla, A. E. Camisasca, L. Ferro, D. Frederiks, F. Frontera, A. Lysenko, M. Maistrello, A. Ridnaia, D. Svinkin, M. Ulanov

AI总结:

利用约两百个长GRB样本检验变率-光度关联,发现其显著性减弱,并识别出高变率、低光度与短MVT组合可作为并合起源的指标。

摘要:

在伽马射线暴(GRB)余辉时代之初,人们发现了大约十几个当时具有红移测量的长暴的瞬时辐射的时间变率V与各向同性等效峰值光度Liso之间存在类似造父变星的关联。不久之后,该关联在约30个GRB的样本中得到了证实,尽管受到显著弥散的影响。与最小变率时标(MVT)不同,V衡量的是短至中等时标上的相对功率。我们旨在利用由Swift、Fermi和Konus/WIND探测到的约两百个具有光谱红移测量的长暴来检验该关联,这些暴的两个观测量均可被精确估计。对于所有选定的GRB,根据原始定义,使用Swift/BAT(Fermi/GBM)在15-150(8-900)keV能量通带内的64毫秒背景扣除光变曲线计算变率。峰值光度要么取自文献,要么通过建模由Konus/WIND或Fermi/GBM获取的宽带谱得出。该关联的统计显著性已减弱至<~2%,主要原因是出现了一些光滑且明亮的GRB,其特征是V相对较小。与大多数长暴不同,4个长时标并合候选体中有3个具有高V和低Liso。光度与由MVT测量的最短时标的关系比与由V测量的短至中等时标的关系更紧密。我们讨论了这些结果对内耗散模型的影响以及e±光球层的作用。我们识别出少数具有单一宽脉冲和低V的光滑GRB,它们可能具有外激波起源,这与大多数GRB相反。高变率(V>~0.1)、低光度(Liso<~10^51 erg s^-1)和短MVT(<~0.1 s)的组合可能是致密双星并合起源的良好指标。

英文摘要:

At the dawn of the gamma-ray burst (GRB) afterglow era, a Cepheid-like correlation was discovered between time variability V and isotropic-equivalent peak luminosity Liso of the prompt emission of about a dozen long GRBs with measured redshift available at that time. Soon afterwards, the correlation was confirmed against a sample of about 30 GRBs, despite being affected by significant scatter. Unlike the minimum variability timescale (MVT), V measures the relative power of short-to-intermediate timescales. We aim to test the correlation using about two hundred long GRBs with spectroscopically measured redshift, detected by Swift, Fermi, and Konus/WIND, for which both observables can be accurately estimated. For all the selected GRBs, variability was calculated according to the original definition using the 64-ms background-subtracted light curves of Swift/BAT (Fermi/GBM) in the 15-150 (8-900) keV energy passband. Peak luminosities were either taken from literature or derived from modelling broad-band spectra acquired with either Konus/WIND or Fermi/GBM. The statistical significance of the correlation has weakened to <~2%, mostly due to the appearance of a number of smooth and luminous GRBs characterised by a relatively small V. At odds with most long GRBs, 3 out of 4 long-duration merger candidates have high V and low Liso. Luminosity is more tightly connected with shortest timescales measured by MVT rather than short-to-intermediate ones, measured by V. We discuss the implications on internal dissipation models and the role of the e+- photosphere. We identified a few, smooth GRBs with a single broad pulse and low V, that might have an external shock origin, in contrast with most GRBs. The combination of high variability (V>~0.1), low luminosity (Liso<~10^51 erg s^-1) and short MVT (<~ 0.1 s) could be a good indicator for a compact binary merger origin.

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。

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