scholarly journals XMM–Newton campaign on ultraluminous X-ray source NGC 1313 X-1: wind versus state variability

2020 ◽  
Vol 492 (4) ◽  
pp. 4646-4665 ◽  
Author(s):  
C Pinto ◽  
D J Walton ◽  
E Kara ◽  
M L Parker ◽  
R Soria ◽  
...  
Keyword(s):  
Accretion Rate ◽  
Compact Object ◽  
Accretion Disc ◽  
Emission Lines ◽  
Time Variability ◽  
Strong Emission ◽  
X Ray ◽  
First Time ◽  
Eddington Limit ◽  
Absorption Features

ABSTRACT Most ultraluminous X-ray sources (ULXs) are thought to be powered by neutron stars and black holes accreting beyond the Eddington limit. If the compact object is a black hole or a neutron star with a magnetic field ≲1012 G, the accretion disc is expected to thicken and launch powerful winds driven by radiation pressure. Evidence of such winds has been found in ULXs through the high-resolution spectrometers onboardXMM–Newton, but several unknowns remain, such as the geometry and launching mechanism of these winds. In order to better understand ULX winds and their link to the accretion regime, we have undertaken a major campaign with XMM–Newton to study the ULX NGC 1313 X-1, which is known to exhibit strong emission and absorption features from a mildly relativistic wind. The new observations show clear changes in the wind with a significantly weakened fast component (0.2c) and the rise of a new wind phase which is cooler and slower (0.06–0.08c). We also detect for the first time variability in the emission lines which indicates an origin within the accretion disc or in the wind. We describe the variability of the wind in the framework of variable super-Eddington accretion rate and discuss a possible geometry for the accretion disc.

scholarly journals An ionized accretion disc wind in Hercules X-1

2019 ◽  
Vol 491 (3) ◽  
pp. 3730-3750
Author(s):  
P Kosec ◽  
A C Fabian ◽  
C Pinto ◽  
D J Walton ◽  
S Dyda ◽  
...  
Keyword(s):  
Accretion Rate ◽  
Compact Object ◽  
Accretion Disc ◽  
Strong Correlations ◽  
X Ray ◽  
Outflow Rate ◽  
Mass Outflow ◽  
X Ray Binaries ◽  
Absorption Features ◽  
Reflection Grating

ABSTRACT Hercules X-1 is one of the best-studied highly magnetized neutron star X-ray binaries with a wealth of archival data. We present the discovery of an ionized wind in its X-ray spectrum when the source is in the high state. The wind detection is statistically significant in most of the XMM–Newton observations, with velocities ranging from 200 to 1000 km s−1. Observed features in the iron K band can be explained by both wind absorption and a forest of iron emission lines. However, we also detect nitrogen, oxygen, and neon absorption lines at the same systematic velocity in the high-resolution Reflection Grating Spectrometer grating spectra. The wind must be launched from the accretion disc, and could be the progenitor of the ultraviolet absorption features observed at comparable velocities, but the latter likely originate at significantly larger distances from the compact object. We find strong correlations between the ionization level of the outflowing material and the ionizing luminosity as well as the superorbital phase. If the luminosity is driving the correlation, the wind could be launched by a combination of Compton heating and radiation pressure. If instead the superorbital phase is the driver for the variations, the observations are likely scanning the wind at different heights above the warped accretion disc. If this is the case, we can estimate the wind mass outflow rate, corrected for the limited launching solid angle, to be roughly 70 per cent of the mass accretion rate.

scholarly journals Super-Eddington accretion discs with advection and outflows around magnetized neutron stars

2019 ◽  
Vol 626 ◽  
pp. A18 ◽  
Author(s):  
Anna Chashkina ◽  
Galina Lipunova ◽  
Pavel Abolmasov ◽  
Juri Poutanen
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Mass Loss ◽  
Accretion Rate ◽  
Accretion Disc ◽  
Accretion Discs ◽  
X Ray ◽  
Radial Profiles ◽  
X Ray Binaries ◽  
Eddington Limit

We present a model for a super-Eddington accretion disc around a magnetized neutron star taking into account advection of heat and the mass loss by the wind. The model is semi-analytical and predicts radial profiles of all the basic physical characteristics of the accretion disc. The magnetospheric radius is found as an eigenvalue of the problem. When the inner disc is in radiation-pressure-dominated regime but does not reach its local Eddington limit, advection is mild, and the radius of the magnetosphere depends weakly on the accretion rate. Once it approaches the local Eddington limit the disc becomes advection-dominated, and the scaling for the magnetospheric radius with the mass accretion rate is similar to the classical Alfvén relation. Allowing for the mass loss in a wind leads to an increase in the magnetospheric radius. Our model can be applied to a wide variety of magnetized neutron stars accreting close to or above their Eddington limits: ultra-luminous X-ray pulsars, Be/X-ray binaries in outbursts, and other systems. In the context of our model we discuss the observational properties of NGC 5907 X-1, the brightest ultra-luminous pulsar currently known, and NGC 300 ULX1, which is apparently a Be/X-ray binary experiencing a very bright super-Eddington outburst.

AGN1 vs AGN2 dichotomy as seen from the point of view of ionized outflows

2019 ◽  
Vol 15 (S356) ◽  
pp. 96-96
Author(s):  
Eleonora Sani
Keyword(s):  
Accretion Rate ◽  
Point Of View ◽  
Emission Lines ◽  
Black Hole Mass ◽  
X Ray ◽  
Bolometric Luminosity ◽  
Wide Range ◽  
Strong Contrast

AbstractI present a detailed study of ionized outflows in a large sample of 650 hard X-ray detected AGN. Taking advantage of the legacy value of the BAT AGN Spectroscopic Survey (BASS, DR1), we are able to reveal the faintest wings of the [OIII] emission lines associated with outflows. The sample allows us to derive the incidence of outflows covering a wide range of AGN bolometric luminosity and test how the outflow parameters are related with various AGN power tracers, such as black hole mass, Eddington ratio, luminosity. I’ll show how ionized outflows are more frequently found in type 1.9 and type 1 AGN (50% and 40%) with respect to the low fraction in type 2 AGN (20%). Within such a framework, I’ll demonstrate how type 2 AGN outflows are almost evenly balanced between blue- and red-shifted winds. This, in strong contrast with type 1 and type 1.9 AGN outflows which are almost exclusively blue-shifted. Finally, I’ll prove how the outflow occurrence is driven by the accretion rate, whereas the dependence of outflow properties with respect to the other AGN power tracers happens to be quite mild.

scholarly journals The Nature of the Compact Object in the Hard X-Ray Source 4U2206+54

2004 ◽  
Vol 194 ◽  
pp. 208-208
Author(s):  
J. M. Torrejón ◽  
I. Kreykenbohni ◽  
A. Orr ◽  
L. Titarchuk ◽  
I. Negueruela
Keyword(s):  
Neutron Star ◽  
Accretion Disk ◽  
Compact Object ◽  
High Energy ◽  
Energy Data ◽  
X Ray ◽  
Hot Plasma ◽  
Cyclotron Line ◽  
First Time

We present an analysis of archival RXTE and BeppoSAX data of the X-ray source 4U2206+54. For the first time, high energy data (≥ 30 keV) is analyzed. The data is well described by comptonization models in which seed photons with temperatures between 1.1 keV arid 1.5 keV are comptonized by a hot plasma at 50 keV thereby producing a hard tail which extends up to 100 keV. From luminosity arguments it is shown that the area of the soft photons source must be small (r ≈ 1 km) and that the presence of an accretion disk in this system is unlikely. Here we report on the possible existence of a cyclotron line around 30 keV . The presence of a neutron star in the system is strongly favored by the available data.

scholarly journals New ASCA Observations of two Anomalous X-ray Pulsars

2000 ◽  
Vol 177 ◽  
pp. 695-698 ◽  
Author(s):  
B. Paul ◽  
M. Kawasaki ◽  
T. Dotani ◽  
F. Nagase
Keyword(s):  
Accretion Rate ◽  
Accretion Disc ◽  
Spectral Shape ◽  
Energy Spectra ◽  
Pulse Profile ◽  
X Ray ◽  
Low Mass ◽  
Low X ◽  
Star Surface ◽  
Made In

AbstractNewASCAobservations of two anomalous X-ray pulsars (AXP) 4U 0142+61 and 1E 1048.1-5937, made in 1998, when compared to earlier observations in 1994 show remarkable stability in the intensity, spectral shape and pulse profile. The energy spectra consist of two components, a power-law and a blackbody emission from the neutron star surface. In IE 1048.1-5937, we have identified three epochs with different spin-down rates and discuss its implications for the magnetar hypothesis of the AXPs. We also note that the spin-down rate and its variations in IE 1048.1-5937 are much larger than what normally can be produced by an accretion disc with very low mass accretion rate corresponding to its low X-ray luminosity.

scholarly journals On producers of cosmic organic compounds: exploring the boron abundance in lithium-rich K giant stars

2017 ◽  
Vol 13 (S332) ◽  
pp. 237-241 ◽  
Author(s):  
N. A. Drake ◽  
R. de la Reza ◽  
V. V. Smith ◽  
K. Cunha
Keyword(s):  
Organic Compounds ◽  
Organic Material ◽  
Emission Lines ◽  
Low Mass Stars ◽  
Strong Emission ◽  
Giant Stars ◽  
First Approximation ◽  
Low Mass ◽  
Stellar Interiors ◽  
First Time

AbstractThe element boron belongs, together with lithium and beryllium, to a known trio of important elements for the study of evolutionary processes in low mass stars. Because B is the least fragile of this trio to be destroyed in the stellar interiors, it can be used to test if the Li enrichment is of planetary origin. Here, for the first time, boron lines are examined in the UV for four giants with different degrees of large Li enrichment by means of observations with the Hubble telescope. Two main results are found in our study. One is that to first approximation B abundances appear not to be in excess, invalidating the planet engulfment mechanism. The second one is that the two stars with very large Li abundances present emission lines indicating that quite strong active chromospheres are acting in these very Li-rich giants. These new results obtained from the UV complement our recent studies in the mid-IR (de la Rezaet al.2015) where strong emission-line features of organic material were found in the spectra of some Li-rich stars.

scholarly journals Phase-targeted X-ray diffraction

2016 ◽  
Vol 49 (5) ◽  
pp. 1561-1571 ◽  
Author(s):  
G. M. Hansford
Keyword(s):  
Rock Specimen ◽  
Low Cost ◽  
Emission Lines ◽  
Quartz Powder ◽  
X Ray Diffraction ◽  
Scattering Angle ◽  
X Ray ◽  
Diffraction Peaks ◽  
First Time ◽  
Xrd Method

A powder X-ray diffraction (XRD) method to enhance the signal of a specific crystalline phase within a mixture is presented for the first time. Specificity to the targeted phase relies on finding coincidences in the ratios of crystal d spacings and the ratios of elemental characteristic X-ray energies. Such coincidences can be exploited so that the two crystal planes diffract through the same scattering angle at two different X-ray energies. An energy-resolving detector placed at the appropriate scattering angle will detect a significantly enhanced signal at these energies if the target mineral or phase is present in the sample. When implemented using high scattering angles, for example 2θ > 150°, the method is tolerant to sample morphology and distance on the scale of ∼2 mm. The principle of the method is demonstrated experimentally using Pd Lα1 and Pd Lβ1 emission lines to enhance the diffraction signal of quartz. Both a pure quartz powder pellet and an unprepared mudstone rock specimen are used to test and develop the phase-targeted method. The technique is further demonstrated in the sensitive detection of retained austenite in steel samples using a combination of In Lβ1 and Ti Kβ emission lines. For both these examples it is also shown how the use of an attenuating foil, with an absorption edge close to and above the higher-energy characteristic X-ray line, can serve to isolate to some degree the coincidence signals from other fluorescence and diffraction peaks in the detected spectrum. The phase-targeted XRD technique is suitable for implementation using low-cost off-the-shelf components in a handheld or in-line instrument format.

scholarly journals Hyperaccretion

2006 ◽  
Vol 2 (S238) ◽  
pp. 31-36
Author(s):  
Andrew R. King
Keyword(s):  
Electron Scattering ◽  
Stellar Mass ◽  
Accretion Disc ◽  
Close Binaries ◽  
X Ray ◽  
Eddington Limit ◽  
Dusty Torus ◽  
Toroidal Geometry

AbstractAccretion at rates exceeding the Eddington limit is common in close binaries. I summarize the arguments leading to the conclusion that such stellar–mass systems appear as ultraluminous X-ray sources when viewed close the the inner accretion disc axis, and like SS433 when viewed from other angles.I show that AGN are unlikely to achieve electron–scattering Eddington ratios as high as ULXs, so there are few ULX analogues among quasars. However hyperaccretion of dusty matter is common among AGN. The resulting outflow naturally has a toroidal geometry, and may well be the origin of the dusty torus invoked in unified AGN schemes.

scholarly journals Models of ultraluminous X-ray transient sources

2020 ◽  
Vol 643 ◽  
pp. A171
Author(s):  
J.-M. Hameury ◽  
J.-P. Lasota
Keyword(s):  
Decay Time ◽  
Binary Systems ◽  
Compact Object ◽  
Accretion Disc ◽  
Accretion Discs ◽  
X Ray ◽  
Analytical Approximations ◽  
Accretion Rates ◽  
Transient Sources ◽  
Peak Luminosity

Context. It is now widely accepted that most ultraluminous X-ray sources (ULXs) are binary systems whose large (above 1039 erg s−1) apparent luminosities are explained by super-Eddington accretion onto a stellar-mass compact object. Many of the ULXs, especially those containing magnetized neutron stars, are highly variable; some exhibit transient behaviour. Large luminosities might imply large accretion discs that could be therefore prone to the thermal–viscous instability known to drive outbursts of dwarf novae and low-mass X-ray binary transient sources. Aims. The aim of this paper is to extend and generalize the X-ray transient disc-instability model to the case of large (outer radius larger than 1012 cm) accretion discs and apply it to the description of systems with super-Eddington accretion rates at outburst and, in some cases, super-Eddington mass transfer rates. Methods. We have used our disc-instability-model code to calculate the time evolution of the accretion disc and the outburst properties. Results. We show that, provided that self-irradiation of the accretion disc is efficient even when the accretion rate exceeds the Eddington value, possibly due to scattering back of the X-ray flux emitted by the central parts of the disc on the outer portions of the disc, heating fronts can reach the disc’s outer edge generating high accretion rates. We also provide analytical approximations for the observable properties of the outbursts. We have successfully reproduced the observed properties of galactic transients with large discs, such as V404 Cyg, as well as some ULXs such as M51 XT-1. Our model can reproduce the peak luminosity and decay time of ESO 243-39 HLX-1 outbursts if the accretor is a neutron star. Conclusions. Observational tests of our predicted relations between the outburst duration and decay time with peak luminosity would be most welcome.

scholarly journals Early Super Soft Source Spectra in RS Oph

2015 ◽  
Vol 2 (1) ◽  
pp. 222-225
Author(s):  
J.-U. Ness
Keyword(s):  
Neutral Hydrogen ◽  
Emission Lines ◽  
X Ray ◽  
Hydrogen Column Density ◽  
Recurrent Nova ◽  
Source Spectra ◽  
Short Time ◽  
First Time ◽  
Shell Ionization

Recent Swift X-ray monitoring campaigns of novae have revealed extreme levels of variability during the early super-softsource (SSS) phase. The first time this was observed was during the 2006 outburst of the recurrent nova RS Oph which was also extensively covered by grating observations with XMM-Newton and Chandra. I focus here on an XMM-Newton observation taken on day 26.1, just before Swift confirmed the start of the SSS phase, and a Chandra observation taken on day 39.7. The first observation probes the evolution of the shock emission produced by the collision of the nova ejecta with the stellar wind of the companion. The second observation contains bright SSS emission longwards of 15°A while at short wavelengths, the shock component can be seen to have hardly changed. On top of the SSS continuum, additional emission lines are clearly seen, and I show that they are much stronger than those seen on day 26.1, indicating line pumping caused by the SSS emission. The lightcurve on day 39.7 is highly variable on short time scales while the long-term Swift light curve was still variable. In 2007, we have shown that brightness variations are followed by hardness variations, lagging behind 1000 seconds. I show now that the hardness variations are owed to variations in the depth of the neutral hydrogen column density of order 25%, particularly affecting the oxygen K-shell ionization edge at 0.5 keV.

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