Research press release



Astronomy: Waking sleeping giants



今回、Erin Karaたちは、X線反響マッピングという手法を用いて、すでに2011年に検出されていた潮汐破壊事象である可能性の高い事象(いわゆる‘Swift J1644+57’)のX線データを再解析し、鉄の光子からのX線エコー(X線反響)の観測について報告している。このX線反響を解析したところ、X線反響が降着流の内側部分に由来しており、反射気体が光の速さの半分の速さで流出していることが明らかになった。


A normally dormant supermassive black hole (SMBH) tearing apart a nearby star is reported in a paper published online in Nature this week. The study analyses X-ray data collected as the star experienced this ‘tidal disruption event’ and accreted onto the SMBH, and opens up a new way of studying gravity effects in normally dormant black holes and, possibly, measuring their spin.

Although our current understanding of space-time around SMBHs is based on actively accreting black holes, 90 per cent of SMBHs are dormant. Tidal disruption events offer an opportunity to study this large population of normally dormant SMBHs.

Erin Kara and colleagues reanalyse previously available X-ray data for a likely tidal disruption event that was detected in 2011, the so-called ‘Swift J1644+57’, using a technique known as X-ray reverberation mapping. They report observations of X-ray echoes, or reverberations, from iron photons. Analysis of these reverberations reveals that they are from the inner part of an accretion flow, with the reflecting gas flowing outwards at up to half the speed of light.

Although the authors do not estimate the spin of the black hole, they propose that, with future improvements in the modelling of such flows, it will be possible to measure black hole spin not only in the 10 per cent of persistently accreting black holes, but also in the 90 per cent of dormant black holes in the Universe.

doi: 10.1038/nature18007|英語の原文

「Nature 関連誌注目のハイライト」は、ネイチャー広報部門が報道関係者向けに作成したリリースを翻訳したものです。より正確かつ詳細な情報が必要な場合には、必ず原著論文をご覧ください。


メールマガジンリストの「Nature 関連誌今週のハイライト」にチェックをいれていただきますと、毎週最新のNature 関連誌のハイライトを皆様にお届けいたします。