这是两篇论文中的第二篇,研究了斯皮策红外光谱仪(IRS)对霍姆伯格II号超铝X射线源(ULX)的观测。在这里,我们进行详细的光电离建模的红外线。我们的分析表明,[O IV] 25.89 $μ$ m发射线的亮度和形态是由软X射线和远紫外线(FUV)辐射的双系统的吸积盘的光致电离和不一致的窄光束。我们表明,发射星云是物质的视线方向和东方的约束,并可能辐射约束到西方。需要超过10 $^{40}$ erg s $^{-1}$的热光度来产生测量的[O IV]通量。我们使用建模和以前发表的研究得出结论,冲击可能贡献很小,如果在所有,在Holmberg II ULX观察到的高电离线通量。此外,我们发现伴星的光谱类型对[O IV]发射的预测强度有着令人惊讶的强烈影响。这一发现可以解释某些含有黑洞双星的星暴系统中[O IV]的起源。
英文摘要:
This is the second of two papers examining Spitzer Infrared Spectrograph (IRS) observations of the ultraluminous X-ray source (ULX) in Holmberg II. Here we perform detailed photoionization modeling of the infrared lines. Our analysis suggests that the luminosity and morphology of the [O IV] 25.89 $μ$m emission line is consistent with photoionization by the soft X-ray and far ultraviolet (FUV) radiation from the accretion disk of the binary system and inconsistent with narrow beaming. We show that the emission nebula is matter-bounded both in the line of sight direction and to the east, and probably radiation-bounded to the west. A bolometric luminosity in excess of 10$^{40}$ erg s$^{-1}$ would be needed to produce the measured [O IV] flux. We use modeling and previously published studies to conclude that shocks likely contribute very little, if at all, to the high-ionization line fluxes observed in the Holmberg II ULX. Additionally, we find that the spectral type of the companion star has a surprisingly strong effect on the predicted strength of the [O IV] emission. This finding could explain the origin of [O IV] in some starburst systems containing black hole binaries.
Unveiling recurrent jets of the ULX Holmberg II X-1: evidence for a massive stellar-mass black hole?
我们报告发现一个明显的三重射电结构隐藏在超亮X射线源Holmberg II X-1的射电泡内。的形态是一致的准直射流结构,观察到发射光学薄的同步辐射。中心部分有一个陡峭的无线电频谱,并且比外部部分更亮,表明重新开始的无线电活动。我们估计最小时间平均喷流功率为2 x 10^{39} erg/s,与时间平均各向同性X射线光度至少为4 x 10^{39} erg/s相关。我们的研究结果表明,Holmberg II X-1是由一个M_BH \geq 25 M_sun的黑洞提供动力的,推测该黑洞以高爱丁顿速率吸积,并伴有间歇性的射电活动。
The evolution of a jet ejection of the ultraluminous X-ray source Holmberg II X-1
利用欧洲VLBI观测网(EVN)、Karl G. Jansky甚大阵列(VLA),以及钱德拉和斯威夫特X射线望远镜。X射线数据显示出明显的硬谱,其稳定的X射线光度彼此相隔4个月。在高分辨率EVN射电观测中,我们探测到了一个毫角秒尺度的扩展源。该源发出非热,可能光学薄同步辐射和其形态是一致的喷射喷射。9-GHz的VLA数据显示了Holmberg II X-1的一个角秒尺度的三重结构,类似于在较低频率下看到的结构。然而,我们发现中央喷射在1.5年内至少消退了7.3倍。我们估计的动力学年龄的喷射要高于2.1年。我们表明,这种快速冷却可以用简单的绝热膨胀损失来解释。Holmberg II X-1的这些性质意味着ULX射电泡可能是由喷出物而不是自吸收的致密喷流膨胀的。
X-ray spectral cut-off and the lack of hard X-ray emission from two ultraluminous X-ray sources M81 X-6 and Holmberg IX X-1
利用Suzaku和XMM-Newton观测数据,对两个超亮X射线源(ULX)M81 X-6和Holmberg IX X-1进行了宽带X射线谱研究。我们进行联合宽带光谱分析的领域中最亮的源,即两个ULX和活动星系核(AGN)在M81,并证明了X射线光谱的ULX截止能量超过约3 keV,在朱雀HXD/PIN带的高能量的贡献可以忽略不计。在10- 30 keV波段,M81 X-6和Holmberg IX X-1的亮度上限分别为3.5e38ergs/s和1.2e39ergs/s。这些极限比M81 X-6的6.8e39ergs/s和Holmberg IX X-1的1.9e40 ergs/s的辐射热光度(0.1-30 keV)低一个数量级以上。我们的研究结果证实了早期的迹象推断,从明亮的ULX的XMM-牛顿观测光谱截止,并表明,没有一个额外的高能量幂律分量显着贡献的X射线发射。这两个ULX的光谱形式与银河系黑洞X射线双星(BHB)或活动星系核(AGN)的光谱形式有很大不同。这意味着ULX既不是恒星质量BHB的简单放大版本,也不是AGN的缩小版本。
Swift observations of the ultraluminous X-ray source Holmberg IX X-1
Holmberg IX X-1是一个著名的超亮X射线源,其X射线亮度约为1 e40 erg/s。斯威夫特的X射线望远镜定期监测该源。自2009年4月以来,该源一直处于扩展的低光度状态。我们利用在不同光度状态下的共加光谱来研究源的光谱行为。简单的幂律和多色盘黑体模型可以排除。然而,最好的整体拟合是由具有冷黑体和暖盘黑体的双热模型提供的。这表明Holmberg IX X-1可能是一个10个太阳质量的黑洞,在比爱丁顿极限高7倍的地方吸积,或者是一个100个太阳质量的最大旋转黑洞,在爱丁顿极限处吸积,我们正在观察吸积盘的内部区域和致密物体的流出物。
X-ray spectral variability in the ultraluminous X-ray source Holmberg IX X-1
我们使用XMM-牛顿和雨燕数据来研究超铝X射线源(ULX),Holmberg IX X-1的光谱变化。光源的光度变化3-4倍,引起相应的光谱变化,这些变化是显著的,但微妙的,并且不能很好地通过简单的硬度比来跟踪。相反,我们共同添加的雨燕数据的强度箱,并做全光谱拟合光盘加上热康普顿模型。所有的数据都很好地拟合了一个低温,光学厚Comptonising日冕,和可变性可以大致的特点是降低温度和增加光学深度的源变得更亮,如预期的那样,如果日冕是逐渐质量加载的材料吹离超爱丁顿内盘。在具有类似光谱的其他ULX中观察到这种可变性行为,但与在具有更软光谱的ULX中观察到的趋势相反。这支持了ULX中存在两种不同的物理机制的想法,其中光谱从由盘状日冕主导到由风主导。
NuSTAR, XMM-Newton and Suzaku Observations of the Ultraluminous X-ray Source Holmberg II X-1
我们提出了第一个宽带0.3-25.0 kev的X射线观测明亮的超亮X射线源(ULX)Holmberg II X-1,由NuSTAR,XMM-Newton和朱雀在2013年9月。NuSTAR的数据提供了Holmberg II X-1在10 keV以上的首次观测,并揭示了一个非常陡峭的高能光谱,类似于NuSTAR迄今为止观测到的其他ULX。这些观测结果进一步表明,ULX表现出的光谱状态通常不会出现在银河系黑洞双星。与其它源的比较表明Holmberg II X-1的吸积率很高,甚至可能超过了Eddington吸积率,软X射线谱(E<10 keV)似乎由两个类黑体发射分量主导,其中较热的一个可能与一个吸积盘有关。然而,所有简单的磁盘模型低于预测的NuSTAR数据以上~10 keV,并需要一个额外的发射组件在最高的能量探测,这意味着NuSTAR数据不下降与维恩光谱。我们调查这样一个额外的高能量的发射组件的物理起源,并赞成的情况下,多余的康普顿散射产生的热电晕的电子与一些属性类似的非常高的状态中看到的银河双星。从这些历元中推断出观测到的0.3-25.0 keV宽波段光度为Lx =(8.1+/-0.1 e39 erg/s,这是Holmberg II X-1的典型特征,大部分通量(约90%)在10 keV以下发射。
Spitzer IRAC observations of IR excess in Holmberg IX X-1: A circumbinary disk or a variable jet?
我们介绍了斯皮策红外线阵列相机(IRAC)的光度观测的超发光X射线源(ULX,X-1)在霍尔姆堡IX。我们构建了一个光谱能量分布(SED)Holmberg IX X-1的基础上公布的光学,紫外和X射线数据结合红外数据从这个分析。我们用磁盘和恒星模型模拟了X射线和光学数据,但是我们发现ULX SED中有一个明显的IR过量,这不能用任何这些模型的拟合或外推来解释。相反,进一步的分析表明,红外过量的结果要么从尘埃排放,可能从一个环双星盘或从一个可变的喷流。
We present C and X-band radio observations of the famous utraluminous X-ray source (ULX) Holmberg IX X-1, previously discovered to be associated with an optical emission line nebula several hundred pc in extent. Our recent infrared study of the ULX suggested that a jet could be responsible for the infrared excess detected at the ULX position. The new radio observations, performed using the Karl G. Jansky Very Large Array (VLA) in B-configuration, reveal the presence of a radio counterpart to the nebula with a spectral slope of -0.56 similar to other ULXs. Importantly, we find no evidence for a…
The X-ray spectral evolution of the ultraluminous X-ray source Holmberg IX X-1
本文对Swift、XMM-Newton和NuSTAR天文台观测到的Holmberg IX X-1原型超亮X射线源(ULX)的X射线谱进行了新的分析。这颗ULX是一个持久的光源,典型的光度约为10^40 erg s^-1,在8年的时间里变化了4 ~ 5倍。我们发现,它的光谱往往演变从相对平坦的或两个组件的光谱中的中等能量带(1-6千电子伏),在较低的光度,光谱是明显弯曲和盘状在最高的光度,与峰值能量在弯曲的光谱往往随着光度的增加而减少。我们认为,ULX的光谱演化可以解释的超级爱丁顿吸积模型,在这种情况下,我们认为ULX的疏散漏斗沿其旋转轴,其大规模的辐射驱动风的范围内。光谱的变化,然后起源于增强的几何光束的吸积率增加,风漏斗变窄,导致从超临界流的中心区域的散射通量比各向同性的热发射风更快地变亮,因此弯曲的硬光谱分量占主导地位,在最高的光度。风也使漏斗边缘的光子向下康普顿散射,导致光谱的峰值能量降低。我们还证实,Holmberg IX X-1显示光谱简并与光度,并建议所观察到的差异自然解释的建议风几何的黑洞旋转轴的进动。
A long-term X-ray monitoring of the ultraluminous X-ray source NGC 5408 X-1 with Swift reveals the presence of dips but no orbital period
NGC 5408 X-1是一个经过充分研究的超亮X射线源(ULX),多年来一直被认为发射出超过恒星质量黑洞爱丁顿极限的X射线。在本文中,我们报告了最广泛的X射线监测的ULX,使用超过四年的观测斯威夫特卫星。我们发现Strohmayer(2009)报告的115天周期在几个周期后就消失了,证实了Foster等人(2010)的怀疑,即周期很可能是超轨道的,而不是系统的轨道周期。我们还报告了一个明确的浸渍行为的来源,可能与(超)轨道现象。所有这些特征都让人想起银河系的X射线双星,并加强了它们与ULX的联系。对倾角进行更深入的观测可以帮助解决对ULX光谱成分解释的模糊性。
X-ray Outflows and Super-Eddington Accretion in the Ultraluminous X-ray Source Holmberg IX X-1
对X射线连续谱发射和通量变化的研究还没有最终揭示在分布的高亮度端(Lx > 1 e40 erg/s)的超亮X射线源(ULX)的性质。这些都是特别感兴趣的,因为光度需要超级爱丁顿吸积到一个质量约10 Msun的黑洞,或更多的标准吸积到一个中等质量的黑洞。超级爱丁顿吸积模型预测了强烈的外流风,使原子吸收线成为极端ULX性质的关键诊断。为了寻找这样的功能,我们已经进行了长期的,500公里的观测活动Holmberg IX X-1与朱雀。这是迄今为止,对于明亮的孤立ULX,铁K带通中最敏感的数据集,但我们在发射或吸收中没有发现统计上显著的原子特征;任何未检测到的窄特征必须具有小于15-20 eV的等效宽度,置信度为99%。如果观察到的质量流入和流出速率之间的趋势延伸到超爱丁顿区域,这些极限远低于预期的>150 eV的线,并且事实上排除了在各种次爱丁顿黑洞中从盘风观察到的线强度。因此,我们不能通过任何实质性的物质柱来观察Holmberg IX X-1的中心区域,排除了球形超爱丁顿吸积模型。如果Holmberg IX X-1是一个超爱丁顿源,任何相关的外流必须具有各向异性的几何形状。最后,铁元素的缺乏表明这颗伴星不可能产生强风,而霍姆伯格IX X-1必须主要通过罗氏瓣溢出吸积。
The magnetic field of ultraluminous X-ray (ULX) pulsars is the key parameter to understand the nature and accretion physics. However, the typical magnetic field values in these ULX pulsars are still under debate. We used six different torque models to study the magnetic fields of ULX pulsars, to see how derived magnetic fields change with different models, and to determine which models are more suitable for ULX pulsars. We took the currently available period, period derivative, and flux data of 7 confirmed ULX pulsars, M82 X-2, ULX NGC 7793 P13, ULX NGC 5907, NGC 300 ULX1, NGC 1313 X-2, M51 UL…
The recent discovery of periodic pulsations from several members of the ultraluminous X-ray source (ULX) family in nearby galaxies as well as in our own galaxy unveiled the nature of the accreting compact object. Neutron stars rather than black holes are currently believed to power a substantial number of ULXs whether or not pulsations are observed. The detection of cyclotron absorption lines in the X-ray spectrum of a ULX provides an alternative way to identify the compact object as a neutron star. Among the non-pulsating ULXs, the presence of a cyclotron resonance scattering feature (CRSF) i…
The accreting compact objects in most of ultraluminous X-ray sources (ULXs) are likely to be neutron stars rather than black holes as suggested by the recent detection of periodic pulsations from some of these sources located in neighboring galaxies and one ULX that has hitherto been discovered in our own galaxy. As a member of the ULX family, NGC 300 ULX1 is a new pulsating ULX (PULX) spinning up at substantially high rates compared with other PULXs. In this paper, the strength of the magnetic field on the surface of the neutron star is inferred from the energy of the cyclotron absorption lin…
Variability is a powerful tool to investigate properties of X-ray binaries (XRB), in particular for Ultraluminous X-ray sources (ULXs) that are mainly detected in the X-ray band. For most ULXs the nature of the accretor is unknown, although a few ULXs have been confirmed to be accreting at super-Eddington rates onto a neutron star (NS). Monitoring these sources is particularly useful both to detect transients and to derive periodicities, linked to orbital and super-orbital modulations. Here we present the results of our monitoring campaign of the galaxy NGC 925, performed with the Neil Gehrels…
We have identified three ultraluminous X-ray sources (ULXs) hosted by globular clusters (GCs) within NGC 1316's stellar system. These discoveries bring the total number of known ULXs in GCs up to 20. We find that the X-ray spectra of the three new sources do not deviate from the established pattern of spectral behaviour of the other known GC ULXs. The consistency of the X-ray spectral behaviour for these sources points to multiple paths of formation and evolution mechanisms for these rare and unique sources. Using the now larger sample of GC ULXs, we compare the optical properties of the entir…
The study of ultraluminous X-ray sources (ULXs) has changed dramatically over the last decade. In this review we first describe the most important observations of ULXs in various wavebands, and across multiple scales in space and time. We discuss recent progress and current unanswered questions. We consider the range of current theories of ULX properties in the light of this observational progress. Applying these models to neutron-star ULXs offers particularly stringent tests, as this is the unique case where the mass of the accretor is effectively fixed.
The origin of the variable X-ray emission in the $(0.3-30)\,$keV energy range of ultraluminous X-ray sources (ULXs) remains unclear, making it difficult to constrain the mass of the central compact object. X-ray luminosities of bright ULXs can be explained with sub-critical accretion ($L<L_{\rm Edd}$) on to an intermediate-mass BH, with the alternative being super-critical accretion on to a stellar-mass BH. Broadband X-ray emission in the former scenario can be explained using the canonical disk plus Comptonizing corona model, whereas in the latter scenario radiation pressure driven massive wi…
Recent observational and theoretical results have suggested that some of ultraluminous X-ray (ULX) sources may contain neutron star (NS) accretors. However, the formation channel and properties of donor stars of NS ULXs remain uncertain. By adopting the non-conservative and rotation-dependent mass transfer model in the primordial binary evolution, we investigate the way to form pulsar ULXs like observed pulsar ULXs in a systematic way. Our simulation results indicate that pulsar ULXs with Be stars and intermediate or/and high mass donors match observed apparent luminosities, orbital periods an…
We report the discovery of possible periodic X-ray dips in a pulsating ultraluminous X-ray source, M51 ULX-7, with the archival Changra observations. With ~20 days of monitoring in the superorbital descending state, we discovered three dips with separations of ~2 and ~8 days via the Bayesian block technique. A phase-dispersion minimization and a $χ^2$ test suggest that the dip is likely recurrent with a period of ~2 days, consistent with the orbital period of M51 ULX-7. We interpret the dip as an obscuring of the emission from the pulsar by the vertical structure on the stream-disk interaction…
We present the results of high-quality XMM-NEWTON observations of a ULX in the galaxy NGC 4190. The detection of spectral cutoff in NGC 4190 ULX1 spectra rules out the interpretation of the ULX to be in a standard low/hard canonical accretion state. We report that the high quality EPIC spectra can be better described by broad thermal component, such as a slim disk. In addition we found long term spectral and flux variability in the source using several XMM-NEWTON and Swift data. A clear anti-correlation between flux and power-law photon index is found which further confirms the unusual spectra…
Most ultraluminous X-ray sources (ULXs) are believed to be stellar mass black holes or neutron stars accreting beyond the Eddington limit. Determining the nature of the compact object and the accretion mode from broadband spectroscopy is currently a challenge, but the observed timing properties provide insight into the compact object and details of the geometry and accretion processes. Here we report a timing analysis for an 800 ks XMM-Newton campaign on the supersoft ultraluminous X-ray source, NGC 247 ULX-1. Deep and frequent dips occur in the X-ray light curve, with the amplitude increasing…
Evidence for candidate X-ray pulsations from the ultraluminous X-ray source NGC 7456 ULX-1
School of Astronomy and Space Science, Nanjing University(南京大学天文与空间科学学院);Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education(南京大学现代天文与天体物理教育部重点实验室)
Ultraluminous X-ray bursts (hereafter ULXBs) are ultraluminous X-ray flares with a fast rise ($\sim$ one minute) and a slow decay ($\sim$ an hour), which are commonly observed in extragalactic globular clusters. Most ULXBs are observational one-off bursts, whereas five flares from the same source in NGC 5128 were discovered by Irwin et al. (2016). In this Letter, we propose a neutron star (NS)-white dwarf (WD) binary model with super-Eddington accretion rates to explain the repeating behavior of the ULXB source in NGC 5128. With an eccentric orbit, the mass transfer occurs at the periastron wh…
Puzzling accretion onto a black hole in the ultraluminous X-ray source M101 ULX-1
对于亮度超过$10^{39}$ erg s $^{-1}$的超亮X射线源(ULX),有两种解释。它们可能是中等质量的黑洞(大于100- 1000,太阳质量,$M_\odot$),以次最大(次爱丁顿)速率辐射,就像银河系黑洞X射线双星一样,但具有更大,更冷的吸积盘。或者,它们可能是以艾丁顿或超艾丁顿速率辐射的恒星质量黑洞。在被发现时,M101 ULX-1的光度为$3\times10^{39}$ erg s $^{-1}$,超软的热盘光谱具有异常低的温度-不受热电子日冕激发的光子的影响-更符合吸积中等质量黑洞的预期外观。在这里,我们报告的光学光谱监测M101 ULX-1。我们证实了先前的建议,该系统包含一个沃尔夫-拉叶星,并揭示了轨道周期为8.2天。这个黑洞的最小质量为$5M_\odot$,更可能是$20-30M_\odot$,但我们认为它不太可能是一个中等质量的黑洞。因此,它在高Eddinton比率下异常柔软的光谱违反了对恒星质量黑洞吸积的预期。吸积必须发生在被捕获的恒星风中,迄今为止,人们一直认为恒星风的效率很低,无法为超亮源提供动力。
Ultraluminous X-ray sources (ULXs) are a class of accreting compact objects with X-ray luminosities above 10$^{39}$ erg s$^{-1}$. The average number of ULXs per galaxy is still not well constrained, especially given the uncertainty on the fraction of ULX transients. Here, we report the identification of a new transient ULX in the galaxy NGC 55 (which we label as ULX-2), thanks to recent XMM-Newton and the Neil Gehrels Swift Observatory observations. This object was previously classified as a transient X-ray source with a luminosity around a few 10$^{38}$ erg s$^{-1}$ in a 2010 XMM-Newton obser…
Multi-wavelength spectroscopic analysis of the ULX Holmberg II X-1 and its nebula suggests the presence of a heavy black hole accreting from a B-type donor
本研究首次对ULX Holmberg II X-1进行多波段光谱分析,发现其光学/紫外辐射来自B型超巨星伴星,而非吸积盘,并推断系统包含约66倍太阳质量的黑洞,可能为引力波源前身。