We calculate profiles of spectral lines from an extended outflow from the compact object (a black hole or a neutron star). We assume that the bulk velocity of the flow increases during a short phase of acceleration and then rapidly decreases forming a failed wind. We also study the wind which is only decelerating. We show that depending on the relative strength of the gravitational redshifting line profiles from such winds may be of several types: distorted P-Cygni (emission and blueshifted absorption); W-shaped (absorption-emission-absorption) and inverted P-Cygni (emission-redshifted absorption). The latter case is expected from accretion flows where the velocity is directed inwards; however, we show that inverted P-Cygni profile can be produced by the failed wind, provided the line is formed within several tens of Schwarzschild radii from the compact object.
Both observational and theoretical evidence point at outflows originating from accretion disks as fundamental ingredients of active galactic nuclei (AGN). These outflows can have more than one component, for example an unbound supersonic wind and a failed wind (FW). The latter is a prediction of the simulations of radiation-driven disk outflows which show that the former is accompanied by an inner failed component, where the flow struggles to escape from the strong gravitational pull of the supermassive black hole. This FW component could provide a physical framework to interpret various pheno…
It has been recently proposed that the broad line region in active galactic nuclei originates from dusty clouds driven from the accretion disk by radiation pressure, at a distance from the black hole where the disk is cooler than the dust sublimation temperature. We test this scenario by checking the consistency of independent broad line region and accretion disk reverberation measurements, for a sample of 11 well studied active galactic nuclei. We show that independent disk and broad line region reverberation mapping measurements are compatible with a universal disk temperature at the Hβ radi…
We report on Chandra gratings spectra of the stellar-mass black hole GRS 1915+105 obtained during a novel, highly obscured state. As the source entered this state, a dense, massive accretion disk wind was detected through strong absorption lines. Photionization modeling indicates that it must originate close to the central engine, orders of magnitude from the outer accretion disk. Strong, nearly sinusoidal flux variability in this phase yielded a key insight: the wind is blue-shifted when its column density is relatively low, but red-shifted as it approaches the Compton-thick threshold. At no …
We analyse behavior of stellar winds of evolved stars and the outcome of SN Ia explosions in the AGN driven relativistic bubble. We find that the expansion of wind shells is efficiently decelerated by the relativistic pressure; their bulk motion however is preserved so they cross the bubble together with the parent star. The wind material occupies a small fraction of bubble volume and does not affect substantially the expansion of SN remnants. The estimated maximal radius of a SN remnant in the bubble is 30-40 pc, if the envelope keeps its integrity and remains spherical. A fragmentation of SN…
Changing look active galactic nuclei (CLAGNs) show complex nature in their X-ray spectral shape and line of sight column density variation. The physical mechanisms responsible for these variations are unclear. Here, we study the spectral properties of a CLAGN, NGC\,1365 using combined {\it XMM-Newton} and {\it NuSTAR} observations to understand the CL behavior. The model fitted mass accretion rate varied between $0.003\pm 0.001$ and $0.009\pm0.002$ $\dot M_{\rm Edd}$ and the dynamic corona changed from $28\pm 3$ to $10\pm1$ $r_g$. We found that the variable absorption column density correlates…
Delving into the depths of NGC 3783 with XRISM VI. Evidence for a failed wind based on Fe xxv absorption line variability
Leiden University（莱顿大学）；SRON Netherlands Institute for Space Research（荷兰空间研究所）；University of Michigan（密歇根大学）；James Madison University（詹姆斯麦迪逊大学）；ESA European Space Research and Technology Centre (ESTEC)（欧洲空间研究与技术中心）；University of Teacher Education Fukuoka（福冈教育大学）；Technion（以色列理工学院）；Massachusetts Institute of Technology（麻省理工学院）；Tokyo University of Science（东京科学大学）
We present new Large Binocular Telescope, Hubble Space Telescope, and Spitzer Space Telescope data for the failed supernova candidate N6946-BH1. We also report an unsuccessful attempt to detect the candidate with Chandra. The ~300,000 Lsun red supergiant progenitor underwent an outburst in 2009 and has since disappeared in the optical. In the LBT data from May 2008 through October 2019, the upper limit on any increase in the R-band luminosity of the source is 2000 Lsun. HST and Spitzer observations show that the source continued to fade in the near-IR and mid-IR, fading by approximately a fact…
We show that for supergiants, net angular momentum is not a necessary condition for forming accretion discs during core-collapse. Even absent net rotation, convective motions in the outer parts of supergiants generate mean horizontal flows at a given radius with velocities of order 1 km/s; the direction of the mean flow will vary as a function of height through the convection zone. We confirm these analytic estimates using Cartesian Boussinesq convection simulations. These mean horizontal flows lead to a random angular momentum in supergiant convection zones that exceeds that of the last stabl…
We perform three-dimensional magnetohydrodynamic simulations of magnetospheric accretion in a T Tauri star to study the accretion and wind structures in the close vicinity of the star. The gas accreting onto the star consists of the gas from the magnetospheric boundary and the failed disk winds. The accreting gas is commonly found as a multi-column accretion, which is consistent with observations. A significant fraction of the angular momentum of the accreting flows is removed by the magnetic fields of conical disk winds and turbulent failed winds inside and near the magnetosphere. As a result…
High resolution X-ray spectroscopy of the warm absorber in the nearby X-ray bright Seyfert 1 galaxy, Mrk 1040 is presented. The observations were carried out in the 2013-2014 timeframe using the Chandra High Energy Transmission Grating with a total exposure of 200 ks. A multitude of absorption lines from Ne, Mg and Si are detected from a wide variety of ionization states. In particular, the detection of inner K-shell absorption lines from Ne, Mg and Si, from charge states ranging from F-like to Li-like ions, suggests the presence of a substantial amount of low ionization absorbing gas, illumin…
We report on a Chandra/HETG X-ray spectrum of the black hole candidate MAXI J1305-704. A rich absorption complex is detected in the Fe L band, including density-sensitive lines from Fe XX, XXI, and XXII. Spectral analysis over three bands with photoionization models generally requires a gas density of n > 1 E+17 cm^-3. Assuming a luminosity of L = 1 E+37 erg/s, fits to the 10-14 A band constrain the absorbing gas to lie within r = 3.9(7) E+3 km from the central engine, or about r = 520 +/- 90 (M/5 Msun) r_g, where r_g = GM/c^2. At this distance from the compact object, gas in Keplerian orbits …
The production of both gravitational waves and short gamma-ray bursts (sGRBs) is widely associated with the merger of compact objects. Several studies have modelled the evolution of the electromagnetic emission using the synchrotron emission produced by the deceleration of both a relativistic top-hat jet seen off-axis, and a wide-angle quasi-spherical outflow (both using numerical studies). In this study we present an analytical model of the synchrotron and synchrotron self-Compton (SSC) emission for an off-axis top-hat jet and a quasi-spherical outflow. We calculate the light curves obtained …
Features and applications of quasi-spherical settling accretion onto rotating magnetized neutron stars in high-mass X-ray binaries are discussed. The settling accretion occurs in wind-fed HMXBs when the plasma cooling time is longer than the free-fall time from the gravitational capture radius, which can take place in low-luminosity HMXBs with $L_x\lesssim 4\times 10^{36}$ erg/s. We briefly review the implications of the settling accretion, focusing on the SFXT phenomenon, which can be related to instability of the quasi-spherical convective shell above the neutron star magnetosphere due to ma…
We use numerical hydrodynamics simulations to study line driven winds launched from an accreting alpha-disc. Building on previous work where the driving radiation field is static, we compute a time-dependent radiation flux from the local, variable accretion rate of the disc. We find that prior to the establishment of a steady state in the disc, variations of ~ 15% in disc luminosity correlate with variations of ~ 2-3 in the mass flux of the wind. After a steady state is reached, when luminosity variations drop to ~ 3%, these correlations vanish as the variability in the mass flux is dominated …
UltraFast Outflows (UFO) are observed in some active galactic nuclei (AGN), with blueshifted and highly ionised Fe-K absorption features. AGN typically have a UV bright accretion flow, so UV line driving is an obvious candidate for launching these winds. However this mechanism requires material with UV opacity, in apparent conflict with the observed high ionisation state of the wind. In this paper we synthesise the X-ray energy spectra resulting from different lines of sight through a state of the art radiation hydrodynamics UV line driven disc wind simulation. We demonstrate that there are so…
Luminous Fast Blue Optical Transients as "Failed" Gravitational-wave Sources: Helium Core$-$Black Hole Mergers Following Delayed Dynamical Instability
Max Planck Institute for Astrophysics（马克斯·普朗克天体物理学研究所）；Columbia University（哥伦比亚大学）；Center for Computational Astrophysics, Flatiron Institute（Flatiron研究所计算天体物理中心）
We perform non-hydrodynamical 2.5D simulations to study the dynamics of material above accretion disk based on the disk radiation pressure acting on dust. We assume a super-accreting underlying disk with the accretion rate of 10 times the Eddington rate with central black hole mass ranging from $10^7$ up to $10^9 M_{\odot}$. Such high accretion rates are characteristic for extreme sources. We show that for high accretors radiatively dust-driving mechanism based on FRADO model always leads to a massive outflow from the disk surface, and the failed wind develops only at larger radii. The outflow…
We present optical spectroscopy obtained with the GTC, VLT and SALT telescopes during the decline of the 2016-2017 outburst of the black hole candidate GRS 1716-249 (Nova Oph 1993). Our 18-epoch data set spans 6 months and reveals that the observational properties of the main emission lines are very variable, even on time scales of a few hours. Several epochs are characterised by P-Cyg (as well as flat-top and asymmetric) profiles in the H$α$, H$β$ and He II ($λ$4686) emission lines, implying the presence of an accretion disc wind, which is likely hot and dense. The wind's terminal velocity ($…
The pulsar emission mechanism in the gamma-ray energy band is poorly understood. Currently, there are several models under discussion in the pulsar community. These models can be constrained by studying the collective properties of a sample of pulsars, which became possible with the large sample of gamma-ray pulsars discovered by the Fermi Large Area Telescope (Fermi-LAT). In this paper we develop a new experimental multi-wavelength technique to determine the beaming factor $\left( f_Ω\right)$ dependance on spin-down luminosity of a set of GeV pulsars. This technique requires three input param…
An accretion disk in an Active Galactic Nucleus (AGN) harbors and shields dust from external illumination: at the mid-plane of the disk around a $M_{\rm BH}=10^{7}M_{\odot}$ black hole, dust can exist at $0.1$pc from the black hole, compared to 0.5pc outside of the disk. We construct a physical model of a disk region approximately located between the radius of dust sublimation at the disk mid-plane and the radius at which dust sublimes at the disk surface. Our main conclusion is that for a wide range of model parameters such as local accretion rate and/or opacity, the accretion disk's own radi…
Runaway O- and early B-type stars passing throughout the interstellar medium at supersonic velocities and characterized by strong stellar winds may produce bow shocks that can serve as particle acceleration sites. Previous theoretical models predict the production of high energy photons by non-thermal radiative processes, but their efficiency is still debated. We aim to test and explain the possibility of emission from the bow shocks formed by runaway stars traveling through the interstellar medium by using previous theoretical models. We apply our model to AE Aurigae, the first reported star …
The great power offered by photoionization models of Active Galactic Nuclei (AGN) emission-line regions has long been mitigated by the fact that very little is known about the spectral energy distribution (SED) between the Lyman limit, where intervening absorption becomes a problem, and 0.3 keV, where soft x-ray observations become possible. The emission lines themselves can, to some degree, be used to probe the SED, but only in the broadest terms. This paper employs a new generation of theoretical SEDs which are internally self-consistent, energy-conserving, and tested against observations, t…
