THE LOCATIONS OF SHORT GAMMA-RAY BURSTS AS EVIDENCE FOR COMPACT OBJECT BINARY PROGENITORS
THE LOCATIONS OF SHORT GAMMA-RAY BURSTS AS EVIDENCE FOR COMPACT OBJECT BINARY PROGENITORS
复制标题
DOI：
10.1088/0004-637x/776/1/18
复制
发表时间：
2013-07
期刊：
影响因子：
--
通讯作者：
W. Fong;E. Berger
中科院分区：
文献类型：
--
作者：
W. Fong;E. Berger
我们详细研究了哈勃太空望远镜对22个短伽马射线暴(GRB)宿主星系和亚星系环境的静止框架UV/光学观测。利用HST的高角度分辨率和深度，我们表征了宿主星系的形态，测量了精确的投影物理和宿主中心之间的归一化偏移，并计算了相对于其宿主光分布(静止帧UV和光学)的爆发的位置。我们计算了短伽玛暴的中位数物理偏移量为4.5kpc，大约是长伽玛暴的3.5kpc，发现≈25%的短伽玛暴具有≳10kpc的偏移量。与它们的宿主大小相比，偏移量的中位数是1.5半光半径(Re)，大约是长伽玛暴、核心塌缩超新星和Ia型超新星的1.5倍。此外，≈20%的短伽玛暴具有≳5RE的偏移量，只有25%的≈位于1RE以内。我们进一步发现，短伽玛暴严重低估了其宿主静止框架的光学和紫外光，其中≈爆发的30%-45%位于其宿主星系中没有可探测到的恒星光的区域，≈55%位于没有紫外光的区域。因此，短伽玛暴不会出现在恒星形成区域，甚至恒星质量区域。这表明，短伽玛暴的祖先系统必须从它们的出生地迁移到它们最终的爆炸地点，这是致密天体双星系统中KICK的特征。利用全样本的偏移量，我们估计了≈20-140kM S−1的初生踢踢速度。这些独立的证据提供了迄今为止最强有力的支持，即短伽玛暴是致密天体双星(NS-NS/NS-BH)合并的结果。
We present a detailed investigation of Hubble Space Telescope rest-frame UV/optical observations of 22 short gamma-ray burst (GRB) host galaxies and sub-galactic environments. Utilizing the high angular resolution and depth of HST we characterize the host galaxy morphologies, measure precise projected physical and host-normalized offsets between the bursts and host centers, and calculate the locations of the bursts with respect to their host light distributions (rest-frame UV and optical). We calculate a median short GRB projected physical offset of 4.5 kpc, about 3.5 times larger than that for long GRBs, and find that ≈25% of short GRBs have offsets of ≳ 10 kpc. When compared to their host sizes, the median offset is 1.5 half-light radii (re), about 1.5 times larger than the values for long GRBs, core-collapse supernovae, and Type Ia supernovae. In addition, ≈20% of short GRBs having offsets of ≳ 5re, and only ≈25% are located within 1re. We further find that short GRBs severely under-represent their hosts' rest-frame optical and UV light, with ≈30%–45% of the bursts located in regions of their host galaxies that have no detectable stellar light, and ≈55% in the regions with no UV light. Therefore, short GRBs do not occur in regions of star formation or even stellar mass. This demonstrates that the progenitor systems of short GRBs must migrate from their birth sites to their eventual explosion sites, a signature of kicks in compact object binary systems. Utilizing the full sample of offsets, we estimate natal kick velocities of ≈20–140 km s−1. These independent lines of evidence provide the strongest support to date that short GRBs result from the merger of compact object binaries (NS–NS/NS–BH).