Stars getting close enough to black holes(BHs)can be torn apart by strong tidal forces,producing electromagnetic flares.To date,more than 100 tidal disruption events(TDEs)have been observed,each involving invariably n...Stars getting close enough to black holes(BHs)can be torn apart by strong tidal forces,producing electromagnetic flares.To date,more than 100 tidal disruption events(TDEs)have been observed,each involving invariably normal gaseous stars whose debris falls onto the BH,sustaining the flares over years.White dwarfs(WDs),which are the most prevalent compact stars and a million times denser-and therefore tougher-than gaseous stars,can only be disrupted by intermediate-mass black holes(IMBHs)of 10^(2)–10^(5) solar masses.WD-TDEs are considered to generate more powerful and short-lived flares,but their evidence has been lacking.Here we report observations of a fast and luminous X-ray transient EP250702a detected by Einstein Probe.Its one-day-long X-ray peak as luminous as 10^(47−49) erg s^(−1) showed strong recurrent flares with hard spectra extending to several tens of MeV gamma-rays,as detected by Fermi/GBM and Konus-Wind,indicating relativistic jet emission.The jet's X-rays dropped sharply from 3×10^(49) erg s^(−1) to around 1044 erg s^(−1) within 20 days(10 days in the source rest frame).These characteristics are inconsistent with any previously known transient phenomena.We suggest that this fast-evolving event over the unprecedentedly short timescale arises likely from disruption of a WD by an IMBH.At late times,a soft component progressively dominates the X-ray spectrum,reaching a luminosity as high as 1044 erg s^(−1),which is consistent with being extreme super-Eddington emission from an accretion disk expected to form in an IMBH-WD TDE.WD-TDEs open a new window for investigating the elusive IMBHs and their surrounding stellar environments,and they are prime sources of gravitational waves in the band of space-based interferometers.展开更多
自2017年发射以来,慧眼硬X射线调制望远镜(Insight Hard X-ray Modulation Telescope,InsightHXMT)凭借着宽能段、大有效面积和高观测频率的优势,已经成为吸积X射线脉冲星研究领域中最重要的天文卫星之一.它在回旋吸收线和吸积物理研究...自2017年发射以来,慧眼硬X射线调制望远镜(Insight Hard X-ray Modulation Telescope,InsightHXMT)凭借着宽能段、大有效面积和高观测频率的优势,已经成为吸积X射线脉冲星研究领域中最重要的天文卫星之一.它在回旋吸收线和吸积物理研究中取得了重要进展,主要包括探测到高能回旋吸收线、揭示回旋线能量的演化和观测到辐射压主导的吸积盘.展开更多
文摘Stars getting close enough to black holes(BHs)can be torn apart by strong tidal forces,producing electromagnetic flares.To date,more than 100 tidal disruption events(TDEs)have been observed,each involving invariably normal gaseous stars whose debris falls onto the BH,sustaining the flares over years.White dwarfs(WDs),which are the most prevalent compact stars and a million times denser-and therefore tougher-than gaseous stars,can only be disrupted by intermediate-mass black holes(IMBHs)of 10^(2)–10^(5) solar masses.WD-TDEs are considered to generate more powerful and short-lived flares,but their evidence has been lacking.Here we report observations of a fast and luminous X-ray transient EP250702a detected by Einstein Probe.Its one-day-long X-ray peak as luminous as 10^(47−49) erg s^(−1) showed strong recurrent flares with hard spectra extending to several tens of MeV gamma-rays,as detected by Fermi/GBM and Konus-Wind,indicating relativistic jet emission.The jet's X-rays dropped sharply from 3×10^(49) erg s^(−1) to around 1044 erg s^(−1) within 20 days(10 days in the source rest frame).These characteristics are inconsistent with any previously known transient phenomena.We suggest that this fast-evolving event over the unprecedentedly short timescale arises likely from disruption of a WD by an IMBH.At late times,a soft component progressively dominates the X-ray spectrum,reaching a luminosity as high as 1044 erg s^(−1),which is consistent with being extreme super-Eddington emission from an accretion disk expected to form in an IMBH-WD TDE.WD-TDEs open a new window for investigating the elusive IMBHs and their surrounding stellar environments,and they are prime sources of gravitational waves in the band of space-based interferometers.
文摘自2017年发射以来,慧眼硬X射线调制望远镜(Insight Hard X-ray Modulation Telescope,InsightHXMT)凭借着宽能段、大有效面积和高观测频率的优势,已经成为吸积X射线脉冲星研究领域中最重要的天文卫星之一.它在回旋吸收线和吸积物理研究中取得了重要进展,主要包括探测到高能回旋吸收线、揭示回旋线能量的演化和观测到辐射压主导的吸积盘.
