恒星形成星系中与短硬GRB 070724 A相关的放射性能量发射的极限
Limits on Radioactive-Powered Emission Associated With a Short-Hard GRB 070724A in a Star-Forming Galaxy
摘要：
我们目前的结果的一个广泛的观测活动的短时间，硬谱伽马射线暴（GRB）070724 A，旨在检测放射性供电的排放，可能遵循一个二进制合并或涉及紧凑的对象崩溃。我们的多波段观测跨越了这个所谓的Li-Paczynski迷你超新星可能活跃的时间范围，从GRB触发的3小时内开始，并代表了对这种发射的一些最深入和最全面的搜索。我们没有发现这种活动的证据，并对核密度物质迅速减压时可能形成的放射性核素的丰度和寿命加以限制。此外，我们的极限比任何先前检测到的与其他GRB相关的宽线Ic型超新星（SN）的峰值幅度要暗得多，有效地排除了与此事件相关的长GRB状SN。考虑到宿主星系的红移（z=0.456），GRB 070724 A代表了一个小的，但不断增长的数量，目前存在的公司物理/restframe数量的短硬GRB之一。GRB 070724 A的宿主是一个中等恒星形成的星系，具有较老的恒星星族组成和相对较高的金属丰度，为12+log（O/H）_KD 02 =9.1。我们没有发现大量的灭绝沿视线，可以掩盖SN爆炸的存在，并估计一个小概率的机会与推定的主机对齐的显着证据。我们讨论了我们的衍生约束如何适应不断发展的图片短硬伽玛暴，他们的潜在的祖先，和主机环境中，他们被认为是生产。
英文摘要：
We present results of an extensive observing campaign of the short duration, hard spectrum gamma-ray burst (GRB) 070724A, aimed at detecting the radioactively-powered emission that might follow from a binary merger or collapse involving compact objects. Our multi-band observations span the range in time over which this so-called Li-Paczynski mini-supernova could be active, beginning within 3 hours of the GRB trigger, and represent some of the deepest and most comprehensive searches for such emission. We find no evidence for such activity and place limits on the abundances and the lifetimes of the possible radioactive nuclides that could form in the rapid decompression of nuclear-density matter. Furthermore, our limits are significantly fainter than the peak magnitude of any previously detected broad-lined Type Ic supernova (SN) associated with other GRBs, effectively ruling out a long GRB-like SN for with this event. Given the unambiguous redshift of the host galaxy (z=0.456), GRB 070724A represents one of a small, but growing, number of short-hard GRBs for which firm physical/restframe quantities currently exist. The host of GRB 070724A is a moderately star-forming galaxy with an older stellar population component and a relatively high metallicity of 12+log(O/H)_KD02=9.1. We find no significant evidence for large amounts of extinction along the line of sight that could mask the presence of a SN explosion and estimate a small probability for chance alignment with the putative host. We discuss how our derived constraints fit into the evolving picture of short-hard GRBs, their potential progenitors, and the host environments in which they are thought to be produced.
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