Colliding Stellar Winds Structure and X-ray Emission

Science.gov (United States)

Pittard, J. M.; Dawson, B.

2018-04-01

We investigate the structure and X-ray emission from the colliding stellar winds in massive star binaries. We find that the opening angle of the contact discontinuity (CD) is overestimated by several formulae in the literature at very small values of the wind momentum ratio, η. We find also that the shocks in the primary (dominant) and secondary winds flare by ≈20° compared to the CD, and that the entire secondary wind is shocked when η ≲ 0.02. Analytical expressions for the opening angles of the shocks, and the fraction of each wind that is shocked, are provided. We find that the X-ray luminosity Lx∝η, and that the spectrum softens slightly as η decreases.

Formation and Evolution of X-ray Binaries

Science.gov (United States)

Shao, Y.

2017-07-01

-donor mass plane increases with the increasing neutron star mass. This may help to explain why some millisecond pulsars with orbital periods longer than ˜ 60 d seem to have less massive white dwarfs than expected. Alternatively, some of these wide binary pulsars may be formed through mass transfer driven by planet/brown dwarf-involved common envelope evolution; (2) Some of the pulsars in compact binaries might have evolved from intermediate-mass X-ray binaries with an anomalous magnetic braking; (3) The equilibrium spin periods of neutron stars in low-mass X-ray binaries are in general shorter than the observed spin periods of binary pulsars by more than one order of magnitude, suggesting that either the simple equilibrium spin model does not apply, or there are other mechanisms/processes spinning down the neutron stars. In Chapter 4, angular momentum loss mechanisms in the cataclysmic variables below the period gap are presented. By considering several kinds of consequential angular momentum loss mechanisms, we find that neither isotropic wind from the white dwarf nor outflow from the L1 point can explain the extra angular momentum loss rate, while an ouflow from the L2 point or a circumbinary disk can effectively extract the angular momentum provided that ˜ 15%-45% of the transferred mass is lost from the binary. A more promising mechanism is a circumbinary disk exerting a gravitational torque on the binary. In this case the mass loss fraction can be as low as ≲ 10-3. In Chapter 5 we present a study on the population of ultraluminous X-ray sources with an accreting neutron star. Most ULXs are believed to be X-ray binary systems, but previous observational and theoretical studies tend to prefer a black hole rather than a neutron star accretor. The recent discovery of 1.37 s pulsations from the ULX M82 X-2 has established its nature as a magnetized neutron star. In this chapter we model the formation history of neutron star ULXs in an M82- or Milky Way-like galaxy, by

Monte Carlo simulations of the detailed iron absorption line profiles from thermal winds in X-ray binaries

Science.gov (United States)

Tomaru, Ryota; Done, Chris; Odaka, Hirokazu; Watanabe, Shin; Takahashi, Tadayuki

2018-05-01

Blueshifted absorption lines from highly ionized iron are seen in some high inclination X-ray binary systems, indicating the presence of an equatorial disc wind. This launch mechanism is under debate, but thermal driving should be ubiquitous. X-ray irradiation from the central source heats disc surface, forming a wind from the outer disc where the local escape velocity is lower than the sound speed. The mass-loss rate from each part of the disc is determined by the luminosity and spectral shape of the central source. We use these together with an assumed density and velocity structure of the wind to predict the column density and ionization state, then combine this with a Monte Carlo radiation transfer to predict the detailed shape of the absorption (and emission) line profiles. We test this on the persistent wind seen in the bright neutron star binary GX 13+1, with luminosity L/LEdd ˜ 0.5. We approximately include the effect of radiation pressure because of high luminosity, and compute line features. We compare these to the highest resolution data, the Chandra third-order grating spectra, which we show here for the first time. This is the first physical model for the wind in this system, and it succeeds in reproducing many of the features seen in the data, showing that the wind in GX13+1 is most likely a thermal-radiation driven wind. This approach, combined with better streamline structures derived from full radiation hydrodynamic simulations, will allow future calorimeter data to explore the detail wind structure.

Formation and Evolution of X-ray Binaries

Science.gov (United States)

Fragkos, Anastasios

X-ray binaries - mass-transferring binary stellar systems with compact object accretors - are unique astrophysical laboratories. They carry information about many complex physical processes such as star formation, compact object formation, and evolution of interacting binaries. My thesis work involves the study of the formation and evolution of Galactic and extra-galacticX-ray binaries using both detailed and realistic simulation tools, and population synthesis techniques. I applied an innovative analysis method that allows the reconstruction of the full evolutionary history of known black hole X-ray binaries back to the time of compact object formation. This analysis takes into account all the available observationally determined properties of a system, and models in detail four of its evolutionary evolutionary phases: mass transfer through the ongoing X-ray phase, tidal evolution before the onset of Roche-lobe overflow, motion through the Galactic potential after the formation of the black hole, and binary orbital dynamics at the time of core collapse. Motivated by deep extra-galactic Chandra survey observations, I worked on population synthesis models of low-mass X-ray binaries in the two elliptical galaxies NGC3379 and NGC4278. These simulations were targeted at understanding the origin of the shape and normalization of the observed X-ray luminosity functions. In a follow up study, I proposed a physically motivated prescription for the modeling of transient neutron star low-mass X-ray binary properties, such as duty cycle, outburst duration and recurrence time. This prescription enabled the direct comparison of transient low-mass X-ray binary population synthesis models to the Chandra X-ray survey of the two ellipticals NGC3379 and NGC4278. Finally, I worked on population synthesismodels of black holeX-ray binaries in the MilkyWay. This work was motivated by recent developments in observational techniques for the measurement of black hole spin magnitudes in

The Physics of Wind-Fed Accretion

International Nuclear Information System (INIS)

Mauche, Christopher W.; Liedahl, Duane A.; Akiyama, Shizuka; Plewa, Tomasz

2008-01-01

We provide a brief review of the physical processes behind the radiative driving of the winds of OB stars and the Bondi-Hoyle-Lyttleton capture and accretion of a fraction of the stellar wind by a compact object, typically a neutron star, in detached high-mass X-ray binaries (HMXBs). In addition, we describe a program to develop global models of the radiatively-driven photoionized winds and accretion flows of HMXBs, with particular attention to the prototypical system Vela X-l. The models combine XSTAR photoionization calculations, HULLAC emission models appropriate to X-ray photoionized plasmas, improved models of the radiative driving of photoionized winds, FLASH time-dependent adaptive-mesh hydrodynamics calculations, and Monte Carlo radiation transport. We present two- and three-dimensional maps of the density, temperature, velocity, ionization parameter, and emissivity distributions of representative X-ray emission lines, as well as synthetic global Monte Carlo X-ray spectra. Such models help to better constrain the properties of the winds of HMXBs, which bear on such fundamental questions as the long-term evolution of these binaries and the chemical enrichment of the interstellar medium.

X-RAY EMISSION FROM THE DOUBLE-BINARY OB-STAR SYSTEM QZ CAR (HD 93206)

International Nuclear Information System (INIS)

Parkin, E. R.; Naze, Y.; Rauw, G.; Broos, P. S.; Townsley, L. K.; Pittard, J. M.; Moffat, A. F. J.; Oskinova, L. M.; Waldron, W. L.

2011-01-01

X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The respective orbits of systems A (O9.7 I+b2 v, P A = 21 days) and B (O8 III+o9 v, P B = 6 days) are reasonably well sampled by the observations, allowing the origin of the X-ray emission to be examined in detail. The X-ray spectra can be well fitted by an attenuated three-temperature thermal plasma model, characterized by cool, moderate, and hot plasma components at kT ≅ 0.2, 0.7, and 2 keV, respectively, and a circumstellar absorption of ≅0.2 x 10 22 cm -2 . Although the hot plasma component could be indicating the presence of wind-wind collision shocks in the system, the model fluxes calculated from spectral fits, with an average value of ≅7 x 10 -13 erg s -1 cm -2 , do not show a clear correlation with the orbits of the two constituent binaries. A semi-analytical model of QZ Car reveals that a stable momentum balance may not be established in either system A or B. Yet, despite this, system B is expected to produce an observed X-ray flux well in excess of the observations. If one considers the wind of the O8 III star to be disrupted by mass transfer, the model and observations are in far better agreement, which lends support to the previous suggestion of mass transfer in the O8 III + o9 v binary. We conclude that the X-ray emission from QZ Car can be reasonably well accounted for by a combination of contributions mainly from the single stars and the mutual wind-wind collision between systems A and B.

Optical and X-ray studies of Compact X-ray Binaries in NGC 5904

Science.gov (United States)

Bhalotia, Vanshree; Beck-Winchatz, Bernhard

2018-06-01

Due to their high stellar densities, globular cluster systems trigger various dynamical interactions, such as the formation of compact X-ray binaries. Stellar collisional frequencies have been correlated to the number of X-ray sources detected in various clusters and we hope to measure this correlation for NGC 5904. Optical fluxes of sources from archival HST images of NGC 5904 have been measured using a DOLPHOT PSF photometry in the UV, optical and near-infrared. We developed a data analysis pipeline to process the fluxes of tens of thousands of objects using awk, python and DOLPHOT. We plot color magnitude diagrams in different photometric bands in order to identify outliers that could be X-ray binaries, since they do not evolve the same way as singular stars. Aligning previously measured astrometric data for X-ray sources in NGC 5904 from Chandra with archival astrometric data from HST will filter out the outlier objects that are not X-ray producing, and provide a sample of compact binary systems that are responsible for X-ray emission in NGC 5904. Furthermore, previously measured X-ray fluxes of NGC 5904 from Chandra have also been used to measure the X-ray to optical flux ratio and identify the types of compact X-ray binaries responsible for the X-ray emissions in NGC 5904. We gratefully acknowledge the support from the Illinois Space Grant Consortium.

X rays from radio binaries

International Nuclear Information System (INIS)

Apparao, K.M.V.

1977-01-01

Reference is made to the radio binary systems CC Cas, AR Lac, β Per (Algol), β Lyr, b Per and Cyg X-1. It is stated that a thermal interpretation of the radiation from Algol requires a much larger x-ray flux than the observed value of 3.8 x 10 -11 erg/cm 2 /sec/keV in the 2 to 6 keV energy range. Observations of some non-thermal flares, together with the small size of the radio source in Algol, indicate that the radio emission is non-thermal in nature. The radio emission is interpreted as synchrotron radiation and it is suggested that the observed x-ray emission is due to inverse Compton scattering of the light of the primary star by the radio electrons. The x-ray emission from other radio binaries is also calculated using this model. The energy for the radio electrons can arise from annihilation of magnetic lines connecting the binary stars, twisted by the rotation of the stars. (U.K.)

EVOLUTION OF INTERMEDIATE-MASS X-RAY BINARIES DRIVEN BY THE MAGNETIC BRAKING OF AP/BP STARS. I. ULTRACOMPACT X-RAY BINARIES

Energy Technology Data Exchange (ETDEWEB)

Chen, Wen-Cong [School of Physics and Electrical Information, Shangqiu Normal University, Shangqiu 476000 (China); Podsiadlowski, Philipp, E-mail: chenwc@pku.edu.cn [Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom)

2016-10-20

It is generally believed that ultracompact X-ray binaries (UCXBs) evolved from binaries consisting of a neutron star accreting from a low-mass white dwarf (WD) or helium star where mass transfer is driven by gravitational radiation. However, the standard WD evolutionary channel cannot produce the relatively long-period (40–60 minutes) UCXBs with a high time-averaged mass-transfer rate. In this work, we explore an alternative evolutionary route toward UCXBs, where the companions evolve from intermediate-mass Ap/Bp stars with an anomalously strong magnetic field (100–10,000 G). Including the magnetic braking caused by the coupling between the magnetic field and an irradiation-driven wind induced by the X-ray flux from the accreting component, we show that intermediate-mass X-ray binaries (IMXBs) can evolve into UCXBs. Using the MESA code, we have calculated evolutionary sequences for a large number of IMXBs. The simulated results indicate that, for a small wind-driving efficiency f = 10{sup −5}, the anomalous magnetic braking can drive IMXBs to an ultra-short period of 11 minutes. Comparing our simulated results with the observed parameters of 15 identified UCXBs, the anomalous magnetic braking evolutionary channel can account for the formation of seven and eight sources with f = 10{sup −3}, and 10{sup −5}, respectively. In particular, a relatively large value of f can fit three of the long-period, persistent sources with a high mass-transfer rate. Though the proportion of Ap/Bp stars in intermediate-mass stars is only 5%, the lifetime of the UCXB phase is ≳2 Gyr, producing a relatively high number of observable systems, making this an alternative evolutionary channel for the formation of UCXBs.

X1908+075: An X-Ray Binary with a 4.4 Day Period

Science.gov (United States)

Wen, Linqing; Remillard, Ronald A.; Bradt, Hale V.

2000-04-01

X1908+075 is an optically unidentified and highly absorbed X-ray source that appeared in early surveys such as Uhuru, OSO 7, Ariel 5, HEAO-1, and the EXOSAT Galactic Plane Survey. These surveys measured a source intensity in the range 2-12 mcrab at 2-10 keV, and the position was localized to ~0.5d. We use the Rossi X-Ray Timing Explorer (RXTE) All-Sky Monitor (ASM) to confirm our expectation that a particular Einstein/IPC detection (1E 1908.4+0730) provides the correct position for X1908+075. The analysis of the coded mask shadows from the ASM for the position of 1E 1908.4+0730 yields a persistent intensity ~8 mcrab (1.5-12 keV) over a 3 yr interval beginning in 1996 February. Furthermore, we detect a period of 4.400+/-0.001 days with a false-alarm probability less than 10-7. The folded light curve is roughly sinusoidal, with an amplitude that is 26% of the mean flux. The X-ray period may be attributed to the scattering and absorption of X-rays through a stellar wind combined with the orbital motion in a binary system. We suggest that X1908+075 is an X-ray binary with a high-mass companion star.

The Swift Supergiant Fast X-ray Transient Project

Science.gov (United States)

Romano, P.; Barthelmy, S.; Bozzo, E.; Burrows, D.; Ducci, L.; Esposito, P.; Evans, P.; Kennea, J.; Krimm, H.; Vercellone, S.

2017-10-01

We present the Swift Supergiant Fast X-ray Transients project, a systematic study of SFXTs and classical supergiant X-ray binaries (SGXBs) through efficient long-term monitoring of 17 sources including SFXTs and classical SGXBs across more than 4 orders of magnitude in X-ray luminosity on timescales from hundred seconds to years. We derived dynamic ranges, duty cycles, and luminosity distributions to highlight systematic differences that help discriminate between different theoretical models proposed to explain the differences between the wind accretion processes in SFXTs and classical SGXBs. Our follow-ups of the SFXT outbursts provide a steady advancement in the comprehension of the mechanisms triggering the high X-ray level emission of these sources. In particular, the observations of the outburst of the SFXT prototype IGR J17544-2619, when the source reached a peak X-ray luminosity of 3×10^{38} erg s^{-1}, challenged for the first time the maximum theoretical luminosity achievable by a wind-fed neutron star high mass X-ray binary. We propose that this giant outburst was due to the formation of a transient accretion disc around the compact object. We also created a catalogue of over 1000 BAT flares which we use to predict the observability and perspectives with future missions.

CARINA OB STARS: X-RAY SIGNATURES OF WIND SHOCKS AND MAGNETIC FIELDS

International Nuclear Information System (INIS)

Gagne, Marc; Fehon, Garrett; Savoy, Michael R.; Cohen, David H.; Townsley, Leisa K.; Broos, Patrick S.; Povich, Matthew S.; Corcoran, Michael F.; Walborn, Nolan R.; Remage Evans, Nancy; Moffat, Anthony F. J.; Naze, Yael; Oskinova, Lida M.

2011-01-01

The Chandra Carina Complex contains 200 known O- and B-type stars. The Chandra survey detected 68 of the 70 O stars and 61 of 127 known B0-B3 stars. We have assembled a publicly available optical/X-ray database to identify OB stars that depart from the canonical L X /L bol relation or whose average X-ray temperatures exceed 1 keV. Among the single O stars with high kT we identify two candidate magnetically confined wind shock sources: Tr16-22, O8.5 V, and LS 1865, O8.5 V((f)). The O4 III(fc) star HD 93250 exhibits strong, hard, variable X-rays, suggesting that it may be a massive binary with a period of >30 days. The visual O2 If* binary HD 93129A shows soft 0.6 keV and hard 1.9 keV emission components, suggesting embedded wind shocks close to the O2 If* Aa primary and colliding wind shocks between Aa and Ab. Of the 11 known O-type spectroscopic binaries, the long orbital-period systems HD 93343, HD 93403, and QZ Car have higher shock temperatures than short-period systems such as HD 93205 and FO 15. Although the X-rays from most B stars may be produced in the coronae of unseen, low-mass pre-main-sequence companions, a dozen B stars with high L X cannot be explained by a distribution of unseen companions. One of these, SS73 24 in the Treasure Chest cluster, is a new candidate Herbig Be star.

UNDERSTANDING THE UNUSUAL X-RAY EMISSION PROPERTIES OF THE MASSIVE, CLOSE BINARY WR 20a: A HIGH ENERGY WINDOW INTO THE STELLAR WIND INITIATION REGION

International Nuclear Information System (INIS)

Montes, Gabriela; Ramirez-Ruiz, Enrico; De Colle, Fabio; Strickler, Rachel

2013-01-01

The problem of explaining the X-ray emission properties of the massive, close binary WR 20a is discussed. Located near the cluster core of Westerlund 2, WR 20a is composed of two nearly identical Wolf-Rayet stars of 82 and 83 solar masses orbiting with a period of only 3.7 days. Although Chandra observations were taken during the secondary optical eclipse, the X-ray light curve shows no signs of a flux decrement. In fact, WR 20a appears slightly more X-ray luminous and softer during the optical eclipse, opposite to what has been observed in other binary systems. To aid in our interpretation of the data, we compare with the results of hydrodynamical simulations using the adaptive mesh refinement code Mezcal which includes radiative cooling and a radiative acceleration force term. It is shown that the X-ray emission can be successfully explained in models where the wind-wind collision interface in this system occurs while the outflowing material is still being accelerated. Consequently, WR 20a serves as a critical test-case for how radiatively driven stellar winds are initiated and how they interact. Our models not only procure a robust description of current Chandra data, which cover the orbital phases between 0.3 and 0.6, but also provide detailed predictions over the entire orbit

Understanding the Unusual X-Ray Emission Properties of the Massive, Close Binary WR 20a: A High Energy Window into the Stellar Wind Initiation Region

Science.gov (United States)

Montes, Gabriela; Ramirez-Ruiz, Enrico; De Colle, Fabio; Strickler, Rachel

2013-11-01

The problem of explaining the X-ray emission properties of the massive, close binary WR 20a is discussed. Located near the cluster core of Westerlund 2, WR 20a is composed of two nearly identical Wolf-Rayet stars of 82 and 83 solar masses orbiting with a period of only 3.7 days. Although Chandra observations were taken during the secondary optical eclipse, the X-ray light curve shows no signs of a flux decrement. In fact, WR 20a appears slightly more X-ray luminous and softer during the optical eclipse, opposite to what has been observed in other binary systems. To aid in our interpretation of the data, we compare with the results of hydrodynamical simulations using the adaptive mesh refinement code Mezcal which includes radiative cooling and a radiative acceleration force term. It is shown that the X-ray emission can be successfully explained in models where the wind-wind collision interface in this system occurs while the outflowing material is still being accelerated. Consequently, WR 20a serves as a critical test-case for how radiatively driven stellar winds are initiated and how they interact. Our models not only procure a robust description of current Chandra data, which cover the orbital phases between 0.3 and 0.6, but also provide detailed predictions over the entire orbit.

UNDERSTANDING THE UNUSUAL X-RAY EMISSION PROPERTIES OF THE MASSIVE, CLOSE BINARY WR 20a: A HIGH ENERGY WINDOW INTO THE STELLAR WIND INITIATION REGION

Energy Technology Data Exchange (ETDEWEB)

Montes, Gabriela; Ramirez-Ruiz, Enrico; De Colle, Fabio; Strickler, Rachel [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2013-11-10

The problem of explaining the X-ray emission properties of the massive, close binary WR 20a is discussed. Located near the cluster core of Westerlund 2, WR 20a is composed of two nearly identical Wolf-Rayet stars of 82 and 83 solar masses orbiting with a period of only 3.7 days. Although Chandra observations were taken during the secondary optical eclipse, the X-ray light curve shows no signs of a flux decrement. In fact, WR 20a appears slightly more X-ray luminous and softer during the optical eclipse, opposite to what has been observed in other binary systems. To aid in our interpretation of the data, we compare with the results of hydrodynamical simulations using the adaptive mesh refinement code Mezcal which includes radiative cooling and a radiative acceleration force term. It is shown that the X-ray emission can be successfully explained in models where the wind-wind collision interface in this system occurs while the outflowing material is still being accelerated. Consequently, WR 20a serves as a critical test-case for how radiatively driven stellar winds are initiated and how they interact. Our models not only procure a robust description of current Chandra data, which cover the orbital phases between 0.3 and 0.6, but also provide detailed predictions over the entire orbit.

Spectral and Timing Nature of the Symbiotic X-Ray Binary 4U 1954+319: The Slowest Rotating Neutron Star in AN X-Ray Binary System

Science.gov (United States)

Enoto, Teruaki; Sasano, Makoto; Yamada, Shin'Ya; Tamagawa, Toru; Makishima, Kazuo; Pottschmidt, Katja; Marcu, Diana; Corbet, Robin H. D.; Fuerst, Felix; Wilms, Jorn

2014-01-01

The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its approx. 5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (is approx. 7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-K alpha line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (approx. 60%-80%), and the location in the Corbet diagram favor high B-field (approx. greater than 10(exp12) G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10(exp33)-10(exp35) erg s(exp-1)), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a approx. 10(exp13) G NS, this scheme can explain the approx. 5.4 hr equilibrium rotation without employing the magnetar-like field (approx. 10(exp16) G) required in the disk accretion case. The timescales of multiple irregular flares (approx. 50 s) can also be attributed to the free-fall time from the Alfv´en shell for a approx. 10(exp13) G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

HIGH-RESOLUTION X-RAY SPECTROSCOPY REVEALS THE SPECIAL NATURE OF WOLF-RAYET STAR WINDS

Energy Technology Data Exchange (ETDEWEB)

Oskinova, L. M.; Hamann, W.-R. [Institute for Physics and Astronomy, University Potsdam, 14476 Potsdam (Germany); Gayley, K. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52245 (United States); Huenemoerder, D. P. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139 (United States); Ignace, R. [Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37663 (United States); Pollock, A. M. T., E-mail: lida@astro.physik.uni-potsdam.de [European Space Agency XMM-Newton Science Operations Centre, European Space Astronomy Centre, Apartado 78, Villanueva de la Canada, 28691 Madrid (Spain)

2012-03-10

We present the first high-resolution X-ray spectrum of a putatively single Wolf-Rayet (WR) star. 400 ks observations of WR 6 by the XMM-Newton telescope resulted in a superb quality high-resolution X-ray spectrum. Spectral analysis reveals that the X-rays originate far out in the stellar wind, more than 30 stellar radii from the photosphere, and thus outside the wind acceleration zone where the line-driving instability (LDI) could create shocks. The X-ray emitting plasma reaches temperatures up to 50 MK and is embedded within the unshocked, 'cool' stellar wind as revealed by characteristic spectral signatures. We detect a fluorescent Fe line at Almost-Equal-To 6.4 keV. The presence of fluorescence is consistent with a two-component medium, where the cool wind is permeated with the hot X-ray emitting plasma. The wind must have a very porous structure to allow the observed amount of X-rays to escape. We find that neither the LDI nor any alternative binary scenario can explain the data. We suggest a scenario where X-rays are produced when the fast wind rams into slow 'sticky clumps' that resist acceleration. Our new data show that the X-rays in single WR star are generated by some special mechanism different from the one operating in the O-star winds.

Optical spectroscopy of the Be/X-ray binary V850 Centauri/GX 304-1 during faint X-ray periodical activity

Science.gov (United States)

Malacaria, C.; Kollatschny, W.; Whelan, E.; Santangelo, A.; Klochkov, D.; McBride, V.; Ducci, L.

2017-07-01

Context. Be/X-ray binaries (BeXRBs) are the most populous class of high-mass X-ray binaries. Their X-ray duty cycle is tightly related to the optical companion wind activity, which in turn can be studied through dedicated optical spectroscopic observations. Aims: We study optical spectral features of the Be circumstellar disk to test their long-term variability and their relation with the X-ray activity. Special attention has been given to the Hα emission line, one of the best tracers of the disk conditions. Methods: We obtained optical broadband medium resolution spectra from a dedicated campaign with the Anglo-Australian Telescope and the Southern African Large Telescope in 2014-2015. Data span over one entire binary orbit, and cover both X-ray quiescent and moderately active periods. We used Balmer emission lines to follow the evolution of the circumstellar disk. Results: We observe prominent spectral features, like double-peaked Hα and Hβ emission lines. The HαV/R ratio significantly changes over a timescale of about one year. Our observations are consistent with a system observed at a large inclination angle (I ≳ 60°). The derived circumstellar disk size shows that the disk evolves from a configuration that prevents accretion onto the neutron star, to one that allows only moderate accretion. This is in agreement with the contemporary observed X-ray activity. Our results are interpreted within the context of inefficient tidal truncation of the circumstellar disk, as expected for this source's binary configuration. We derived the Hβ-emitting region size, which is equal to about half of the corresponding Hα-emitting disk, and constrain the luminosity class of V850 Cen as III-V, consistent with the previously proposed class.

ON NEUTRAL ABSORPTION AND SPECTRAL EVOLUTION IN X-RAY BINARIES

International Nuclear Information System (INIS)

Miller, J. M.; Cackett, E. M.; Reis, R. C.

2009-01-01

Current X-ray observatories make it possible to follow the evolution of transient and variable X-ray binaries across a broad range in luminosity and source behavior. In such studies, it can be unclear whether evolution in the low-energy portion of the spectrum should be attributed to evolution in the source, or instead to evolution in neutral photoelectric absorption. Dispersive spectrometers make it possible to address this problem. We have analyzed a small but diverse set of X-ray binaries observed with the Chandra High Energy Transmission Grating Spectrometer across a range in luminosity and different spectral states. The column density in individual photoelectric absorption edges remains constant with luminosity, both within and across source spectral states. This finding suggests that absorption in the interstellar medium strongly dominates the neutral column density observed in spectra of X-ray binaries. Consequently, evolution in the low-energy spectrum of X-ray binaries should properly be attributed to evolution in the source spectrum. We discuss our results in the context of X-ray binary spectroscopy with current and future X-ray missions.

What Can Simbol-X Do for Gamma-ray Binaries?

Science.gov (United States)

Cerutti, B.; Dubus, G.; Henri, G.; Hill, A. B.; Szostek, A.

2009-05-01

Gamma-ray binaries have been uncovered as a new class of Galactic objects in the very high energy sky (>100 GeV). The three systems known today have hard X-ray spectra (photon index ~1.5), extended radio emission and a high luminosity in gamma-rays. Recent monitoring campaigns of LSI +61°303 in X-rays have confirmed variability in these systems and revealed a spectral hardening with increasing flux. In a generic one-zone leptonic model, the cooling of relativistic electrons accounts for the main spectral and temporal features observed at high energy. Persistent hard X-ray emission is expected to extend well beyond 10 keV. We explain how Simbol-X will constrain the existing models in connection with Fermi Space Telescope measurements. Because of its unprecedented sensitivity in hard X-rays, Simbol-X will also play a role in the discovery of new gamma-ray binaries, giving new insights into the evolution of compact binaries.

What Can Simbol-X Do for Gamma-ray Binaries?

International Nuclear Information System (INIS)

Cerutti, B.; Dubus, G.; Henri, G.; Hill, A. B.; Szostek, A.

2009-01-01

Gamma-ray binaries have been uncovered as a new class of Galactic objects in the very high energy sky (>100 GeV). The three systems known today have hard X-ray spectra (photon index ∼1.5), extended radio emission and a high luminosity in gamma-rays. Recent monitoring campaigns of LSI +61 deg. 303 in X-rays have confirmed variability in these systems and revealed a spectral hardening with increasing flux. In a generic one-zone leptonic model, the cooling of relativistic electrons accounts for the main spectral and temporal features observed at high energy. Persistent hard X-ray emission is expected to extend well beyond 10 keV. We explain how Simbol-X will constrain the existing models in connection with Fermi Space Telescope measurements. Because of its unprecedented sensitivity in hard X-rays, Simbol-X will also play a role in the discovery of new gamma-ray binaries, giving new insights into the evolution of compact binaries.

INTERFERENCE AS AN ORIGIN OF THE PEAKED NOISE IN ACCRETING X-RAY BINARIES

Energy Technology Data Exchange (ETDEWEB)

Veledina, Alexandra, E-mail: alexandra.veledina@gmail.com [Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)

2016-12-01

We propose a physical model for the peaked noise in the X-ray power density spectra of accreting X-ray binaries. We interpret its appearance as an interference of two Comptonization continua: one coming from the upscattering of seed photons from the cold thin disk and the other fed by the synchrotron emission of the hot flow. Variations of both X-ray components are caused by fluctuations in mass accretion rate, but there is a delay between them corresponding to the propagation timescale from the disk Comptonization radius to the region of synchrotron Comptonization. If the disk and synchrotron Comptonization are correlated, the humps in the power spectra are harmonically related and the dips between them appear at frequencies related as odd numbers 1:3:5. If they are anti-correlated, the humps are related as 1:3:5, but the dips are harmonically related. Similar structures are expected to be observed in accreting neutron star binaries and supermassive black holes. The delay can be easily recovered from the frequency of peaked noise and further used to constrain the combination of the viscosity parameter and disk height-to-radius ratio α ( H / R ){sup 2} of the accretion flow. We model multi-peak power spectra of black hole X-ray binaries GX 339–4 and XTE J1748–288 to constrain these parameters.

Optical studies of massive X-ray binaries

International Nuclear Information System (INIS)

Zuiderwijk, E.J.

1979-01-01

Photometric and spectroscopic studies of several optical counterparts of massive X-ray binaries are presented. Subjects of study were the binary systems:HD77581/4U0900-40 (Vela X-1), HD153919/4U1700-37, Wray 977/4U1223-62 and Sk160/4U0115-74 (=SMC X-1). (Auth.)

Do some x-ray stars have white dwarf companions

Science.gov (United States)

Mccollum, Bruce

1995-01-01

Some Be stars which are intermittent X-ray sources may have white dwarf companions rather than neutron stars. It is not possible to prove or rule out the existence of Be + WD systems using X-ray or optical data. However, the presence of a white dwarf could be established by the detection of its EUV continuum shortward of the Be star's continuum turnover at 100 A. Either the detection or the nondetection of Be + WD systems would have implications for models of Be star variability, models of Be binary system formation and evolution, and models of wind-fed accretion.

An X-ray and optical study of the ultracompact X-ray binary A 1246-58

NARCIS (Netherlands)

in 't Zand, J.J.M.; Bassa, C.G.; Jonker, P.G.; Keek, L.; Verbunt, F.W.M.; Méndez, M.; Markwardt, C.B.

2008-01-01

Results are discussed of an X-ray and optical observation campaign of the low-mass X-ray binary A 1246-58 performed with instruments on Satellite per Astronomia X ("BeppoSAX"), the Rossi X-ray Timing Explorer (RXTE), the X-ray Multi-mirror Mission ("XMM-Newton"), the Swift mission, and the Very

Optical observations of binary X-ray sources

International Nuclear Information System (INIS)

Boynton, P.E.

1975-01-01

The contribution to the recent progress in astronomy made by optical observations is pointed out. The optical properties of X-ray sources help to establish the physical nature of these objects. The current observational evidence on the binary X-ray sources HZ Her/Her X-1 and HDE 226868/Cyg X-1 is reported. (P.J.S.)

The hypersoft state of Cygnus X-3. A key to jet quenching in X-ray binaries?

Science.gov (United States)

Koljonen, K. I. I.; Maccarone, T.; McCollough, M. L.; Gurwell, M.; Trushkin, S. A.; Pooley, G. G.; Piano, G.; Tavani, M.

2018-04-01

Context. Cygnus X-3 is a unique microquasar in the Galaxy hosting a Wolf-Rayet companion orbiting a compact object that most likely is a low-mass black hole. The unique source properties are likely due to the interaction of the compact object with the heavy stellar wind of the companion. Aim. In this paper, we concentrate on a very specific period of time prior to the massive outbursts observed from the source. During this period, Cygnus X-3 is in a so-called hypersoft state, in which the radio and hard X-ray fluxes are found to be at their lowest values (or non-detected), the soft X-ray flux is at its highest values, and sporadic γ-ray emission is observed. We use multiwavelength observations to study the nature of the hypersoft state. Methods: We observed Cygnus X-3 during the hypersoft state with Swift and NuSTAR in X-rays and SMA, AMI-LA, and RATAN-600 in the radio. We also considered X-ray monitoring data from MAXI and γ-ray monitoring data from AGILE and Fermi. Results: We found that the spectra and timing properties of the multiwavelength observations can be explained by a scenario in which the jet production is turned off or highly diminished in the hypersoft state and the missing jet pressure allows the wind to refill the region close to the black hole. The results provide proof of actual jet quenching in soft states of X-ray binaries.

Symbiotic Stars in X-rays

Science.gov (United States)

Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.

2014-01-01

hard X-ray emission from the innermost accretion region. Since we have identified the elusive accretion component in the emission from a sample of symbiotic stars, our results have implications for the understanding of wind-fed mass transfer in wide binaries, and the accretion rate in one class of candidate progenitors of type Ia supernovae.

X-ray binaries, part 1

International Nuclear Information System (INIS)

Hammerschlag-Hensberge, G.C.M.J.

1977-01-01

Optical observations of X-ray binaries and their interpretation are described. A number of early-type stars which are identified as companions of X-ray sources are photometrically and spectroscopically observed. The spectra were obtained with the coude spectrograph attached to the 1.5 m telescope of the European Southern Observatory, La Silla, Chile. Registrations of the spectra were made with the Faul-Coradi microphotometer of the Observatory at Utrecht. To study radial velocity variations, the positions of the spectral lines were measured with the Grant comparator of the University of Groningen

NuSTAR Hard X-Ray Observation of the Gamma-Ray Binary Candidate HESS J1832–093

DEFF Research Database (Denmark)

Mori, Kaya; Gotthelf, E. V.; Hailey, Charles J.

2017-01-01

−093, is detected up to ~30 keV and is well-described by an absorbed power-law model with a best-fit photon index . A re-analysis of archival Chandra and XMM-Newton data finds that the long-term X-ray flux increase of XMMU J183245−0921539 is (90% C.L.), much less than previously reported. A search for a pulsar spin...... of XMMU J183245−0921539 are most consistent with a non-accreting binary generating synchrotron X-rays from particle acceleration in the shock formed as a result of the pulsar and stellar wind collision. We also report on three nearby hard X-ray sources, one of which may be associated with diffuse emission...

Distortion of absorption-line velocity curves due to x-ray heating in x-ray binaries

International Nuclear Information System (INIS)

Milgrom, M.

1976-01-01

The effects of X-ray heating on the measured absorption line velocities, in X-ray binaries with low X-rays to optical luminosities ratio are considered. These effects may be appreciable even for such binaries where the effect of X-ray heating on the light-curve is negligible. The effects are studied qualitatively and suggest possible ways to partially eliminate the systematic errors introduced by them. The individual systems Cyg x-1 and SMC x-1 are treated and the results of numerical calculations are presented for them. For Cyg x-1 it is found that the effect is detectable during the X-ray 'high' state in all regions of the spectrum. During the 'low' state it may be important in the red region of the spectrum. The results for the case in which soft X-ray fluxes (E < or approximately .4 keV, suggested by theoretical models) are present are also given. For SMC x-1 a strong effect for Hα, Hβ, Hγ had been found. This effect may be responsible for the observed variable velocity curve. We also find for SMC x-1 that the average X-ray intensity falling on the primary must be considerably smaller than what is derived from the detected flux, or else the effect is too large. (author)

Observations and numerical studies of gamma-ray emission in colliding-wind binaries

International Nuclear Information System (INIS)

Reitberger, K.

2014-01-01

Massive stars in binary systems have long been regarded as potential sources of high-energy gamma rays. The emission is thought to arise in the region where the stellar winds collide, thereby producing accelerated particles which subsequently emit gamma rays.This scenario is supported by observations with the Fermi Large Area Telescope presented in this thesis. To address the underlying emission mechanisms in a quantitative way, numerical simulations that incorporate hydrodynamics, the acceleration of charged particles as well as the subsequent gamma-ray emission were found to be needed.This thesis presents the analysis of a high-energy gamma-ray source and its identification with the particle-accelerating colliding-wind binary system Eta Carinae. In order to go beyond the present understanding of such objects, this work provides detailed description of a new 3D-hydrodynamical model, which incorporates the line-driven acceleration of the winds, gravity, orbital motion and the radiative cooling of the shocked plasma, as well as the diffusive shock acceleration of charged particles in the wind collision region. In a subsequent step we simulate and study the resulting gamma-ray emission via relativistic bremsstrahlung, anisotropic inverse Compton radiation and neutral pion decay. (author) [de

Physics of accretion and ejection processes: a multi-wavelengths study of galactic X-ray binaries

International Nuclear Information System (INIS)

Prat, Lionel

2010-01-01

This manuscript is dedicated to the study of the accretion and ejection processes in X-ray Binaries, using radio and X-ray observations as well as numerical simulations. The links and interplay between the accretion disc, the corona and the compact jet. In an introductory part, I first describe the main observational and theoretical properties of the X-ray binaries. I especially emphasize the aspects required to understand the work reported in this manuscript. I also describe the main X-ray and radio observatories used during this work. Then, the first part of this manuscript is dedicated to the accretion processes in X-ray Binaries. I use high energy observations to study one High Mass X-ray Binary (IGR J19140+0951) and two Low-Mass X-ray Binaries (XTE J1818-245 and H1743-322). In the case of IGR Jl9140+0951, observations show that the luminosity generated by the accretion processes can deeply alter the stellar wind. In the case of the two Low Mass X-ray Binaries, I estimate several important parameters of the Systems using the behavior of their accretion discs. The second part is dedicated to the interplay between the accretion disc and the other components of the Systems, namely the corona and the compact jet. Using simultaneous X-ray and radio observations, I show that the corona undergo a strong evolution prior to a discrete ejection of matter, in the case of several binary Systems. In the case of GRS 1915+105, evolution of the corona and detection of a discrete ejection appear within a few seconds, while for other sources it takes a few hours. I study also the link between the accretion disc and the compact jet using a correlation between radio and X-ray flux: depending on the System, the link between the accretion energy brought by the accretion disc and the luminosity of the jet is different, indicating that different physical processes are at work. Finally, the third part is dedicated to numerical simulations of the accretion disc, in the case where an

X-ray reflection in oxygen-rich accretion discs of ultracompact X-ray binaries

DEFF Research Database (Denmark)

Madej, O. K.; Garcia, Jeronimo; Jonker, P. G.

2014-01-01

We present spectroscopic X-ray data of two candidate ultracompact X-ray binaries (UCXBs): 4U 0614+091 and 4U 1543-624. We confirm the presence of a broad O viii Ly alpha reflection line (at a parts per thousand 18 angstrom) using XMM-Newton and Chandra observations obtained in 2012 and 2013. The ...

Mass accretion rate fluctuations in black hole X-ray binaries

NARCIS (Netherlands)

Rapisarda, S.

2017-01-01

This thesis is about the first systematic and quantitative application of propagating mass accretion rate fluctuations models to black hole X-ray binaries. Black hole X-ray binaries are systems consisting of a solar mass star orbiting around a stellar mass black hole. Eventually, the black hole

Stellar X-Ray Polarimetry

Science.gov (United States)

Swank, J.

2011-01-01

Most of the stellar end-state black holes, pulsars, and white dwarfs that are X-ray sources should have polarized X-ray fluxes. The degree will depend on the relative contributions of the unresolved structures. Fluxes from accretion disks and accretion disk corona may be polarized by scattering. Beams and jets may have contributions of polarized emission in strong magnetic fields. The Gravity and Extreme Magnetism Small Explorer (GEMS) will study the effects on polarization of strong gravity of black holes and strong magnetism of neutron stars. Some part of the flux from compact stars accreting from companion stars has been reflected from the companion, its wind, or accretion streams. Polarization of this component is a potential tool for studying the structure of the gas in these binary systems. Polarization due to scattering can also be present in X-ray emission from white dwarf binaries and binary normal stars such as RS CVn stars and colliding wind sources like Eta Car. Normal late type stars may have polarized flux from coronal flares. But X-ray polarization sensitivity is not at the level needed for single early type stars.

Ultracompact X-ray binary stars

NARCIS (Netherlands)

Haaften, L.M. van

2013-01-01

Ultracompact X-ray binary stars usually consist of a neutron star and a white dwarf, two stars bound together by their strong gravity and orbiting each other very rapidly, completing one orbit in less than one hour. Neutron stars are extremely compact remnants of the collapsed cores of massive stars

Roche-Lobe overflow in X-ray binaries, ch. 2

International Nuclear Information System (INIS)

Savonije, G.J.

1977-01-01

It is examined whether Roche-lobe overflow can be the main mechanism of mass transfer that powers the low-mass as well as the massive X-ray binaries. Detailed numerical computations of the initial phase of Roche-lobe overflow were performed in order to determine the precise time development of the mass transfer from normal stars with masses ranging from 1.5 M(sun) up to 20 M(sun) to compact companions with masses of 1 and 1.5 M(sun). The binary code includes a simplified hydrodynamical treatment of Roche-lobe overflow. For massive primaries this hydrodynamical treatment appears to result in much longer X-ray lifetimes than obtained in previous investigations. The calculations also include effects of slow, non-synchronous rotation of the contact star and loss of mass and angular momentum from the binary system. For Her X-1 and Cen X-3 X-ray lifetimes of the order of 10 5 and 10 4 yrs are predicted, respectively

CLASSIFYING X-RAY BINARIES: A PROBABILISTIC APPROACH

International Nuclear Information System (INIS)

Gopalan, Giri; Bornn, Luke; Vrtilek, Saeqa Dil

2015-01-01

In X-ray binary star systems consisting of a compact object that accretes material from an orbiting secondary star, there is no straightforward means to decide whether the compact object is a black hole or a neutron star. To assist in this process, we develop a Bayesian statistical model that makes use of the fact that X-ray binary systems appear to cluster based on their compact object type when viewed from a three-dimensional coordinate system derived from X-ray spectral data where the first coordinate is the ratio of counts in the mid- to low-energy band (color 1), the second coordinate is the ratio of counts in the high- to low-energy band (color 2), and the third coordinate is the sum of counts in all three bands. We use this model to estimate the probabilities of an X-ray binary system containing a black hole, non-pulsing neutron star, or pulsing neutron star. In particular, we utilize a latent variable model in which the latent variables follow a Gaussian process prior distribution, and hence we are able to induce the spatial correlation which we believe exists between systems of the same type. The utility of this approach is demonstrated by the accurate prediction of system types using Rossi X-ray Timing Explorer All Sky Monitor data, but it is not flawless. In particular, non-pulsing neutron systems containing “bursters” that are close to the boundary demarcating systems containing black holes tend to be classified as black hole systems. As a byproduct of our analyses, we provide the astronomer with the public R code which can be used to predict the compact object type of XRBs given training data

ON THE APPARENT LACK OF Be X-RAY BINARIES WITH BLACK HOLES

International Nuclear Information System (INIS)

Belczynski, Krzysztof; Ziolkowski, Janusz

2009-01-01

In our Galaxy there are 64 Be X-ray binaries known to date. Out of these, 42 host a neutron star (NS), and for the remainder the nature of the companion is unknown. None, so far, are known to host a black hole (BH). There seems to be no apparent mechanism that would prevent formation or detection of Be stars with BHs. This disparity is referred to as a missing Be-BH X-ray binary problem. We point out that current evolutionary scenarios that lead to the formation of Be X-ray binaries predict that the ratio of binaries with NSs to the ones with BHs is rather high, F NStoBH ∼ 10-50, with the more likely formation models providing the values at the high end. The ratio is a natural outcome of (1) the stellar initial mass function that produces more NSs than BHs and (2) common envelope evolution (i.e., a major mechanism involved in the formation of interacting binaries) that naturally selects progenitors of Be X-ray binaries with NSs (binaries with comparable mass components have more likely survival probabilities) over ones with BHs (which are much more likely to be common envelope mergers). A comparison of this ratio (i.e., F NStoBH ∼ 30) with the number of confirmed Be-NS X-ray binaries (42) indicates that the expected number of Be-BH X-ray binaries is of the order of only ∼0-2. This is entirely consistent with the observed Galactic sample.

Non-thermal Processes in Colliding-wind Massive Binaries: the Contribution of Simbol-X to a Multiwavelength Investigation

Science.gov (United States)

De Becker, Michaël; Blomme, Ronny; Micela, Giusi; Pittard, Julian M.; Rauw, Gregor; Romero, Gustavo E.; Sana, Hugues; Stevens, Ian R.

2009-05-01

Several colliding-wind massive binaries are known to be non-thermal emitters in the radio domain. This constitutes strong evidence for the fact that an efficient particle acceleration process is at work in these objects. The acceleration mechanism is most probably the Diffusive Shock Acceleration (DSA) process in the presence of strong hydrodynamic shocks due to the colliding-winds. In order to investigate the physics of this particle acceleration, we initiated a multiwavelength campaign covering a large part of the electromagnetic spectrum. In this context, the detailed study of the hard X-ray emission from these sources in the SIMBOL-X bandpass constitutes a crucial element in order to probe this still poorly known topic of astrophysics. It should be noted that colliding-wind massive binaries should be considered as very valuable targets for the investigation of particle acceleration in a similar way as supernova remnants, but in a different region of the parameter space.

Catalogue of high-mass X-ray binaries in the Galaxy (4th edition)

NARCIS (Netherlands)

Liu, Q.Z.; van Paradijs, J.; van den Heuvel, E.P.J.

2006-01-01

We present a new edition of the catalogue of high-mass X-ray binaries in the Galaxy. The catalogue contains source name(s), coordinates, finding chart, X-ray luminosity, system parameters, and stellar parameters of the components and other characteristic properties of 114 high-mass X-ray binaries,

News on the X-ray emission from hot subdwarf stars

Directory of Open Access Journals (Sweden)

Palombara Nicola La

2017-12-01

Full Text Available In latest years, the high sensitivity of the instruments on-board the XMM-Newton and Chandra satellites allowed us to explore the properties of the X-ray emission from hot subdwarf stars. The small but growing sample of X-ray detected hot subdwarfs includes binary systems, in which the X-ray emission is due to wind accretion onto a compact companion (white dwarf or neutron star, as well as isolated sdO stars, in which X-rays are probably due to shock instabilities in the wind. X-ray observations of these low-mass stars provide information which can be useful for our understanding of the weak winds of this type of stars and can lead to the discovery of particularly interesting binary systems. Here we report the most recent results we have recently obtained in this research area.

FORMATION OF BLACK HOLE X-RAY BINARIES IN GLOBULAR CLUSTERS

International Nuclear Information System (INIS)

Ivanova, N.; Heinke, C. O.; Woods, T. E.; Chaichenets, S.; Fregeau, J.; Lombardi, J. C.

2010-01-01

Inspired by the recent identification in extragalactic globular clusters of the first candidate black hole-white dwarf (BH-WD) X-ray binaries, where the compact accretors may be stellar-mass black holes (BHs), we explore how such binaries could be formed in a dynamical environment. We provide analyses of the formation rates via well-known formation channels like binary exchange and physical collisions and propose that the only possibility of forming BH-WD binaries is via coupling these usual formation channels with subsequent hardening and/or triple formation. In particular, we find that the most important mechanism for the creation of a BH-WD X-ray binary from an initially dynamically formed BH-WD binary is mass transfer induced in a triple system via the Kozai mechanism. Furthermore, we find that BH-WD binaries that evolve into X-ray sources can be formed by exchanges of a BH into a WD-WD binary or possibly by collisions of a BH and a giant star. If BHs undergo significant evaporation from the cluster or form a completely detached subcluster of BHs, then we cannot match the observationally inferred production rates even using the most optimistic estimates of formation rates. To explain the observations with stellar-mass BH-WD binaries, at least 1% of all formed BHs, or presumably 10% of the BHs present in the core now, must be involved in interactions with the rest of the core stellar population.

Herschel OBSERVATIONS OF DUST AROUND THE HIGH-MASS X-RAY BINARY GX 301-2

Energy Technology Data Exchange (ETDEWEB)

Servillat, M. [Laboratoire Univers et Théories (CNRS/INSU, Observatoire de Paris, Université Paris Diderot), 5 place Jules Janssen, F-92190 Meudon (France); Coleiro, A.; Chaty, S. [Laboratoire AIM (CEA/Irfu/SAp, CNRS/INSU, Universit Paris Diderot), CEA Saclay, Bat. 709, F-91191 Gif-sur-Yvette (France); Rahoui, F. [Harvard University, Department of Astronomy, 60 Garden Street, Cambridge, MA 02138 (United States); Zurita Heras, J. A., E-mail: mathieu.servillat@obspm.fr [AstroParticule et Cosmologie (Université Paris Diderot, CNRS/IN2P3, CEA/DSM, Observatoire de Paris, Sorbonne Paris Cité), 10 rue Alice Domon et Léonie Duquet, F-75205 Paris Cedex 13 (France)

2014-12-20

We aim at characterizing the structure of the gas and dust around the high-mass X-ray binary GX 301-2, a highly obscured X-ray binary hosting a hypergiant (HG) star and a neutron star, in order to better constrain its evolution. We used Herschel PACS to observe GX 301-2 in the far infrared and completed the spectral energy distribution of the source using published data or catalogs from the optical to the radio range (0.4 to 4 × 10{sup 4} μm). GX 301-2 is detected for the first time at 70 and 100 μm. We fitted different models of circumstellar (CS) environments to the data. All tested models are statistically acceptable, and consistent with an HG star at ∼3 kpc. We found that the addition of a free-free emission component from the strong stellar wind is required and could dominate the far-infrared flux. Through comparisons with similar systems and discussion on the estimated model parameters, we favor a disk-like CS environment of ∼8 AU that would enshroud the binary system. The temperature goes down to ∼200 K at the edge of the disk, allowing for dust formation. This disk is probably a rimmed viscous disk with an inner rim at the temperature of the dust sublimation temperature (∼1500 K). The similarities between the HG GX 301-2, B[e] supergiants, and the highly obscured X-ray binaries (particularly IGR J16318-4848) are strengthened. GX 301-2 might represent a transition stage in the evolution of massive stars in binary systems, connecting supergiant B[e] systems to luminous blue variables.

Time variability of X-ray binaries: observations with INTEGRAL. Modeling

International Nuclear Information System (INIS)

Cabanac, Clement

2007-01-01

The exact origin of the observed X and Gamma ray variability in X-ray binaries is still an open debate in high energy astrophysics. Among others, these objects are showing aperiodic and quasi-periodic luminosity variations on timescales as small as the millisecond. This erratic behavior must put constraints on the proposed emission processes occurring in the vicinity of the neutrons star or the stellar mass black-hole held by these objects. We propose here to study their behavior following 3 different ways: first we examine the evolution of a particular X-ray source discovered by INTEGRAL, IGR J19140+0951. Using timing and spectral data given by different instruments, we show that the source type is plausibly consistent with a High Mass X-ray Binary hosting a neutrons star. Subsequently, we propose a new method dedicated to the study of timing data coming from coded mask aperture instruments. Using it on INTEGRAL/ISGRI real data, we detect the presence of periodic and quasi-periodic features in some pulsars and micro-quasars at energies as high as a hundred keV. Finally, we suggest a model designed to describe the low frequency variability of X-ray binaries in their hardest state. This model is based on thermal comptonization of soft photons by a warm corona in which a pressure wave is propagating in cylindrical geometry. By computing both numerical simulations and analytical solution, we show that this model should be suitable to describe some of the typical features observed in X-ray binaries power spectra in their hard state and their evolution such as aperiodic noise and low frequency quasi-periodic oscillations. (author) [fr

The Ultracompact Nature of the Black Hole Candidate X-Ray Binary 47 Tuc X9

Science.gov (United States)

Bahramian, Arash; Heinke, Craig O.; Tudor, Vlad; Miller-Jones, James C. A.; Bogdanov, Slavko; Maccarone, Thomas J.; Knigge, Christian; Sivakoff, Gregory R.; Chomiuk, Laura; Strader, J.;

CHANDRA CHARACTERIZATION OF X-RAY EMISSION IN THE YOUNG F-STAR BINARY SYSTEM HD 113766

International Nuclear Information System (INIS)

Lisse, C. M.; Christian, D. J.; Wolk, S. J.; Günther, H. M.; Chen, C. H.; Grady, C. A.

2017-01-01

Using Chandra , we have obtained imaging X-ray spectroscopy of the 10–16 Myr old F-star binary HD 113766. We individually resolve the 1.″4 separation binary components for the first time in the X-ray and find a total 0.3–2.0 keV luminosity of 2.2 × 10 29 erg s −1 , consistent with previous RASS estimates. We find emission from the easternmost, infrared-bright, dusty member HD 113766A to be only ∼10% that of the western, infrared-faint member HD 113766B. There is no evidence for a 3rd late-type stellar or substellar member of HD 113766 with L x  > 6 × 10 25 erg s −1 within 2′ of the binary pair. The ratio of the two stars’ X-ray luminosity is consistent with their assignments as F2V and F6V by Pecaut et al. The emission is soft for both stars, kT Apec  = 0.30–0.50 keV, suggesting X-rays produced by stellar rotation and/or convection in young dynamos, but not accretion or outflow shocks, which we rule out. A possible 2.8 ± 0.15 (2 σ ) hr modulation in the HD 113766B X-ray emission is seen, but at very low confidence and of unknown provenance. Stellar wind drag models corresponding to L x  ∼ 2 × 10 29 erg s −1 argue for a 1 mm dust particle lifetime around HD 113766B of only ∼90,0000 years, suggesting that dust around HD 113766B is quickly removed, whereas 1 mm sized dust around HD 113766A can survive for >1.5 × 10 6 years. At 10 28 –10 29 erg s −1 X-ray luminosity, astrobiologically important effects, like dust warming and X-ray photolytic organic synthesis, are likely for any circumstellar material in the HD 113766 systems.

Astronomy and astrophysics of galactic X-ray binaries: from the nature of the X-ray sources to the physics of accretion processes

International Nuclear Information System (INIS)

Rodriguez, Jerome

2010-01-01

In this HDR (Accreditation to supervise research) report, the author proposes an overview of his research works in the field of accretion of X-ray binaries. After a presentation of X-ray binaries, neutron stars and black holes, micro-quasars, and of the main issues regarding X-ray binaries, the author presents and comments his activities in X-ray astronomy and gamma-ray astronomy (the INTEGRAL observatory, the discovery of new sources of X and gamma radiation, studies of new sources at different wavelengths). The second part addresses the understanding of source accretion: phenomenological studies in astronomy, relationships between accretion and ejection. The third part presents and comments several studies of the physics of phenomena related to matter accretion and ejection. (author) [fr

OSO-8 observing schedule for x-ray binaries

International Nuclear Information System (INIS)

Thomas, R.J.

1976-01-01

Six different instruments on OSO-8 have observed several binary x-ray sources between energies of 0.13 keV and 1 MeV at various times since June 21, 1975. The schedule for these observations is given, as well as the present plan for such future observations through July 1976. Included is the OSO-8 observing schedule for the transient x-ray source A0620-00

Low-mass X-ray binary evolution and the origin of millisecond pulsars

Science.gov (United States)

Frank, Juhan; King, Andrew R.; Lasota, Jean-Pierre

1992-01-01

The evolution of low-mass X-ray binaries (LMXBs) is considered. It is shown that X-ray irradiation of the companion stars causes these systems to undergo episodes of rapid mass transfer followed by detached phases. The systems are visible as bright X-ray binaries only for a short part of each cycle, so that their space density must be considerably larger than previously estimated. This removes the difficulty in regarding LMXBs as the progenitors of low-mass binary pulsars. The low-accretion-rate phase of the cycle with the soft X-ray transients is identified. It is shown that 3 hr is likely to be the minimum orbital period for LMXBs with main-sequence companions and it is suggested that the evolutionary endpoint for many LMXBs may be systems which are the sites of gamma-ray bursts.

Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni During Quiescence

DEFF Research Database (Denmark)

Rana, Vikram; Loh, Alan; Corbel, Stephane

2016-01-01

We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broadband (0...

A SEARCH FOR X-RAY EMISSION FROM COLLIDING MAGNETOSPHERES IN YOUNG ECCENTRIC STELLAR BINARIES

Energy Technology Data Exchange (ETDEWEB)

Getman, Konstantin V.; Broos, Patrick S. [Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802 (United States); Kóspál, Ágnes [Konkoly Observatory, Research Center for Astronomy and Earth Sciences, Hungarian Academy of Sciences, P.O. Box 67, 1525 Budapest (Hungary); Salter, Demerese M. [Department of Astronomy and Laboratory for Millimeter-Wave Astronomy, University of Maryland, College Park, MD 20742 (United States); Garmire, Gordon P. [Huntingdon Institute for X-ray Astronomy, LLC, 10677 Franks Road, Huntingdon, PA 16652 (United States)

2016-12-01

Among young binary stars whose magnetospheres are expected to collide, only two systems have been observed near periastron in the X-ray band: the low-mass DQ Tau and the older and more massive HD 152404. Both exhibit elevated levels of X-ray emission at periastron. Our goal is to determine whether colliding magnetospheres in young high-eccentricity binaries commonly produce elevated average levels of X-ray activity. This work is based on Chandra snapshots of multiple periastron and non-periastron passages in four nearby young eccentric binaries (Parenago 523, RX J1622.7-2325 Nw, UZ Tau E, and HD 152404). We find that for the merged sample of all four binaries the current X-ray data show an increasing average X-ray flux near periastron (at a ∼2.5-sigma level). Further comparison of these data with the X-ray properties of hundreds of young stars in the Orion Nebula Cluster, produced by the Chandra Orion Ultradeep Project (COUP), indicates that the X-ray emission from the merged sample of our binaries cannot be explained within the framework of the COUP-like X-ray activity. However, due to the inhomogeneities of the merged binary sample and the relatively low statistical significance of the detected flux increase, these findings are regarded as tentative only. More data are needed to prove that the flux increase is real and is related to the processes of colliding magnetospheres.

Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

Science.gov (United States)

Madau, Piero; Fragos, Tassos

2017-05-01

We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior to and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z ≲ 4. Together with an updated empirical determination of the cosmic history of star formation, recent modeling of the stellar mass-metallicity relation, and a scheme for absorption by the IGM that accounts for the presence of ionized H II bubbles during the epoch of reionization, our detailed calculations provide refined predictions of the X-ray volume emissivity and filtered radiation background from “normal” galaxies at z ≳ 6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. Because of the energy dependence of photoabsorption, soft X-ray photons are produced by local sources, while more energetic radiation arrives unattenuated from larger cosmological volumes. While the filtering of X-ray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct He I photoionizations are the main source of IGM heating, and the temperature of the largely neutral medium in between H II cavities increases above the temperature of the cosmic microwave background (CMB) only at z ≲ 10, when the volume filling factor of H II bubbles is already ≳0.1. Therefore, in this scenario, it is only at relatively late epochs that neutral intergalactic hydrogen

Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

Energy Technology Data Exchange (ETDEWEB)

Madau, Piero [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Fragos, Tassos [Geneva Observatory, University of Geneva, Chemin des Maillettes 51, 1290 Sauverny (Switzerland)

2017-05-01

We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior to and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z ≲ 4. Together with an updated empirical determination of the cosmic history of star formation, recent modeling of the stellar mass–metallicity relation, and a scheme for absorption by the IGM that accounts for the presence of ionized H ii bubbles during the epoch of reionization, our detailed calculations provide refined predictions of the X-ray volume emissivity and filtered radiation background from “normal” galaxies at z ≳ 6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. Because of the energy dependence of photoabsorption, soft X-ray photons are produced by local sources, while more energetic radiation arrives unattenuated from larger cosmological volumes. While the filtering of X-ray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct He i photoionizations are the main source of IGM heating, and the temperature of the largely neutral medium in between H ii cavities increases above the temperature of the cosmic microwave background (CMB) only at z ≲ 10, when the volume filling factor of H ii bubbles is already ≳0.1. Therefore, in this scenario, it is only at relatively late epochs that neutral intergalactic

High-energy gamma-ray emission in compact binaries

International Nuclear Information System (INIS)

Cerutti, Benoit

2010-01-01

Four gamma-ray sources have been associated with binary systems in our Galaxy: the micro-quasar Cygnus X-3 and the gamma-ray binaries LS I +61 degrees 303, LS 5039 and PSR B1259-63. These systems are composed of a massive companion star and a compact object of unknown nature, except in PSR B1259-63 where there is a young pulsar. I propose a comprehensive theoretical model for the high-energy gamma-ray emission and variability in gamma-ray emitting binaries. In this model, the high-energy radiation is produced by inverse Compton scattering of stellar photons on ultra-relativistic electron-positron pairs injected by a young pulsar in gamma-ray binaries and in a relativistic jet in micro-quasars. Considering anisotropic inverse Compton scattering, pair production and pair cascade emission, the TeV gamma-ray emission is well explained in LS 5039. Nevertheless, this model cannot account for the gamma-ray emission in LS I +61 degrees 303 and PSR B1259-63. Other processes should dominate in these complex systems. In Cygnus X-3, the gamma-ray radiation is convincingly reproduced by Doppler-boosted Compton emission of pairs in a relativistic jet. Gamma-ray binaries and micro-quasars provide a novel environment for the study of pulsar winds and relativistic jets at very small spatial scales. (author)

Low Mass X-ray Binary 4U1705-44 Exiting an Extended High X-ray State

Science.gov (United States)

Phillipson, Rebecca; Boyd, Patricia T.; Smale, Alan P.

2017-09-01

The neutron-star low-mass X-ray binary 4U1705-44, which exhibited high amplitude long-term X-ray variability on the order of hundreds of days during the 16-year continuous monitoring by the RXTE ASM (1995-2012), entered an anomalously long high state in July 2012 as observed by MAXI (2009-present).

A self-regulating braking mechanism in black-hole X-ray binaries

International Nuclear Information System (INIS)

Meyer, F.; Meyer-Hofmeister, E.

2001-01-01

The outbursts of black hole X-ray transients can be understood as caused by a limit cycle instability in the accretion disk, similar to dwarf nova outbursts. For adequately low mass overflow rates from the companion star long outburst recurrence times are expected. Buth the fact that we find predominantly long recurrence times or that only one X-ray nova outburst was detected at all poses a problem. The question arises whether any braking mechanism could act in a way that long recurrence times are favoured. We suggest that a circumbinary disk exists and brakes the orbital motion of the binary stars by tidal interaction. The irradiation during an outburst leads to mass loss by winds from the circumbinary disk, relieving the braking force until the removed matter is refilled by diffusion from outer parts. We show that this reduction of braking will self-adjust the mass transfer to the marginal rate that gives long recurrence times. (orig.)

Observational studies of X-ray binary systems

International Nuclear Information System (INIS)

Klis, M. van der.

1983-01-01

The subject of Chapter 1 is theoretical. The other chapters, Ch. 2 to 6, contain original observational data and efforts towards their interpretation. Of these, Ch. 3, 4 and 5 deal with massive X-ray binaries, Ch. 6 with low-mass systems and Ch. 2 with Cygnus X-3, which we have not yet been able to assign to any of these two classes. The X-ray observations described were made with the COS-B satellite. Work based on UV and optical observations is described in Ch. 5. The UV observations were made with the IUE satellite, the optical observations at several ground-based observatories. (Auth.)

Smearing of mass accretion rate variation by viscous processes in accretion disks in compact binary systems

Science.gov (United States)

Ghosh, A.; Chakrabarti, Sandip K.

2016-09-01

Variation of mass supply rate from the companion can be smeared out by viscous processes inside an accretion disk. Hence, by the time the flow reaches the inner edge, the variation in X-rays need not reflect the true variation of the mass supply rate at the outer edge. However, if the viscosity fluctuates around a mean value, one would expect the viscous time scale t_{{visc}} also to spread around a mean value. In high mass X-ray binaries, which are thought to be primarily wind-fed, the size of the viscous Keplerian disk is smaller and thus such a spread could be lower as compared to the low mass X-ray binaries which are primarily fed by Roche lobe overflow. If there is an increasing or decreasing trend in viscosity, the interval between enhanced emission would be modified systematically. In the absence of a detailed knowledge about the variation of mass supply rates at the outer edge, we study ideal circumstances where modulation must take place exactly in orbital time scales, such as when there is an ellipticity in the orbit. We study a few compact binaries using long term All Sky monitor (ASM) data (1.5-12 keV) of Rossi X-ray Timing Explorer (RXTE) and all sky survey data (15-50 keV) of Swift satellites by different methods to look for such smearing effects and to infer what these results can tell us about the viscous processes inside the respective disks. We employ three different methods to seek imprints of periodicity on the X-ray variation and found that in all the cases, the location of the peak in the power density spectra is consistent with the orbital frequencies. Interestingly, in high mass X-ray binaries the peaks are sharp with high rms values, consistent with a small Keplerian disk in a wind fed system. However, in low mass X-ray binaries with larger Keplerian disk component, the peaks are spreaded out with much lower rms values. X-ray reflections, or superhump phenomena which may also cause such X-ray modulations would not be affected by the size of

CHANDRA CHARACTERIZATION OF X-RAY EMISSION IN THE YOUNG F-STAR BINARY SYSTEM HD 113766

Energy Technology Data Exchange (ETDEWEB)

Lisse, C. M. [Planetary Exploration Branch, Space Exploration Sector, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Christian, D. J. [Department of Physics and Astronomy, California State University Northridge, 18111 Nordhoff Street, Northridge, CA 91330 (United States); Wolk, S. J. [Chandra X-ray Center, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Günther, H. M. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, NE83-569, Cambridge, MA 02139 (United States); Chen, C. H. [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Grady, C. A., E-mail: carey.lisse@jhuapl.edu, E-mail: damian.christian@csun.edu, E-mail: swolk@cfa.harvard.edu, E-mail: hgunther@mit.edu, E-mail: cchen@stsci.edu, E-mail: carol.a.grady@nasa.gov [Eureka Scientific and Goddard Space Flight Center, Code 667, NASA-GSFC, Greenbelt, MD 20771 (United States)

2017-02-01

Using Chandra , we have obtained imaging X-ray spectroscopy of the 10–16 Myr old F-star binary HD 113766. We individually resolve the 1.″4 separation binary components for the first time in the X-ray and find a total 0.3–2.0 keV luminosity of 2.2 × 10{sup 29} erg s{sup −1}, consistent with previous RASS estimates. We find emission from the easternmost, infrared-bright, dusty member HD 113766A to be only ∼10% that of the western, infrared-faint member HD 113766B. There is no evidence for a 3rd late-type stellar or substellar member of HD 113766 with L {sub x} > 6 × 10{sup 25} erg s{sup −1} within 2′ of the binary pair. The ratio of the two stars’ X-ray luminosity is consistent with their assignments as F2V and F6V by Pecaut et al. The emission is soft for both stars, kT {sub Apec} = 0.30–0.50 keV, suggesting X-rays produced by stellar rotation and/or convection in young dynamos, but not accretion or outflow shocks, which we rule out. A possible 2.8 ± 0.15 (2 σ ) hr modulation in the HD 113766B X-ray emission is seen, but at very low confidence and of unknown provenance. Stellar wind drag models corresponding to L {sub x} ∼ 2 × 10{sup 29} erg s{sup −1} argue for a 1 mm dust particle lifetime around HD 113766B of only ∼90,0000 years, suggesting that dust around HD 113766B is quickly removed, whereas 1 mm sized dust around HD 113766A can survive for >1.5 × 10{sup 6} years. At 10{sup 28}–10{sup 29} erg s{sup −1} X-ray luminosity, astrobiologically important effects, like dust warming and X-ray photolytic organic synthesis, are likely for any circumstellar material in the HD 113766 systems.

A ROTSE-I/ROSAT Survey of X-ray Emission from Contact Binary Stars

Science.gov (United States)

Geske, M.; McKay, T.

2005-05-01

Using public data from the ROSAT All Sky Survey (RASS) and the ROTSE-I Sky Patrols, the incidence of strong x-ray emissions from contact binary systems was examined. The RASS data was matched to an expanded catalog of contact binary systems from the ROTSE-I data, using a 35 arc second radius. X-ray luminosities for matching objects were then determined. This information was then used to evaluate the total x-ray emissions from all such objects, in order to determine their contribution to the galactic x-ray background.

Different X-ray spectral evolution for black hole X-ray binaries in dual tracks of radio-X-ray correlation

International Nuclear Information System (INIS)

Cao, Xiao-Feng; Wu, Qingwen; Dong, Ai-Jun

2014-01-01

Recently, an 'outlier' track of radio-X-ray correlation was found, which is much steeper than the former universal correlation, where dual tracks were speculated to be triggered by different accretion processes. In this work, we test this issue by exploring hard X-ray spectral evolution in four black-hole X-ray binaries with multiple, quasi-simultaneous radio and X-ray observations. First, we find that hard X-ray photon indices, Γ, are negatively and positively correlated with X-ray fluxes when the X-ray flux, F 3-9 keV , is below and above a critical flux, F X, crit , which are consistent with predictions of the advection-dominated accretion flow and the disk-corona model, respectively. Second, and most importantly, we find that the radio-X-ray correlations are also clearly different when the X-ray fluxes are higher and lower than the critical flux as defined by X-ray spectral evolution. The data points with F 3-9 keV ≳ F X, crit have a steeper radio-X-ray correlation (F X ∝F R b and b ∼ 1.1-1.4), which roughly forms the ''outlier'' track. However, the data points with anti-correlation of Γ – F 3-9 keV either stay in the universal track with b ∼ 0.61 or stay in the transition track (from the universal to 'outlier' tracks or vice versa). Therefore, our results support that the universal and ''outlier'' tracks of radio-X-ray correlations are regulated by radiatively inefficient and radiatively efficient accretion model, respectively.

Effects of radiation pressure on the equipotential surfaces in X-ray binaries

Science.gov (United States)

Kondo, Y.; Mccluskey, G. E., Jr.; Gulden, S. L.

1976-01-01

Equipotential surfaces incorporating the effect of radiation pressure were computed for the X-ray binaries Cen X-3, Cyg X-1 = HDE 226868, Vela XR-1 = 3U 0900-40 = HD 77581, and 3U 1700-37 = HD 153919. The topology of the equipotential surfaces is significantly affected by radiation pressure. In particular, the so-called critical Roche (Jacobian) lobes, the traditional figure 8's, do not exist. The effects of these results on modeling X-ray binaries are discussed.

Effects of radiation pressure on the equipotential surfaces in x-ray binaries

International Nuclear Information System (INIS)

Kondo, Y.; McCluskey, G.E. Jr.; Gulden, S.L.

1976-01-01

Equipotential surfaces incorporating the effect of radiation pressure were computed for the x-ray binaries Cen X-3, Cyg X-1 = HDE 226868, Vela XR-1 = 3U 0900-40 = HD 77581, and 3U 1700-37 = HD 153919. The topology of the equipotential surfaces is significantly affected by radiation pressure. In particular, the so-called critical Roche (Jacobian) lobes, the traditional figure 8's, do not exist. The effects of these results on modeling x-ray binaries are discussed

On the origin of highly ionized X-ray absorbers detected in the galactic X-ray binaries

International Nuclear Information System (INIS)

Luo, Yang; Fang, Taotao

2014-01-01

X-ray observations of the Galactic X-ray binaries (XRBs) revealed numerous highly ionized metal absorption lines. However, it is unclear whether such lines are produced by the hot interstellar medium (ISM) or the circumstellar medium intrinsic to the binaries. Here we present a Chandra X-ray absorption line study of 28 observations of 12 XRBs, with a focus on the Ne IX and Fe XVII lines. We report the first detections of these lines in a significant amount of observations. We do not find a significant dependence of the line equivalent width on the distance of the XRBs, but we do see a weak dependence on the source X-ray luminosity. We also find 2 out of 12 selected targets show strong temporal variation of the Ne IX absorbers. While the line ratio between the two ion species suggests a temperature consistent with the previous predictions of the ISM, comparing with two theoretical models of the ISM shows the observed column densities are significantly higher than predictions. On the other hand, photoionization by the XRBs provides a reasonably good fit to the data. Our findings suggest that a significant fraction of these X-ray absorbers may originate in the hot gas intrinsic to the XRBs, and that the ISM makes small, if not negligible, contribution. We briefly discuss the implications to the study of the Milky Way hot gas content.

HST spectrum and timing of the ultracompact X-ray binary candidate 47 Tuc X9

Science.gov (United States)

Tudor, V.; Miller-Jones, J. C. A.; Knigge, C.; Maccarone, T. J.; Tauris, T. M.; Bahramian, A.; Chomiuk, L.; Heinke, C. O.; Sivakoff, G. R.; Strader, J.; Plotkin, R. M.; Soria, R.; Albrow, M. D.; Anderson, G. E.; van den Berg, M.; Bernardini, F.; Bogdanov, S.; Britt, C. T.; Russell, D. M.; Zurek, D. R.

2018-05-01

To confirm the nature of the donor star in the ultracompact X-ray binary candidate 47 Tuc X9, we obtained optical spectra (3000-10 000 Å) with the Hubble Space Telescope / Space Telescope Imaging Spectrograph. We find no strong emission or absorption features in the spectrum of X9. In particular, we place 3σ upper limits on the H α and He II λ4686 emission line equivalent widths - EWH α ≲ 14 Å and -EW_{He {II}} ≲ 9 Å, respectively. This is much lower than seen for typical X-ray binaries at a similar X-ray luminosity (which, for L_2-10 keV ≈ 10^{33}-10^{34} erg s-1 is typically - EWH α ˜ 50 Å). This supports our previous suggestion, by Bahramian et al., of an H-poor donor in X9. We perform timing analysis on archival far-ultraviolet, V- and I-band data to search for periodicities. In the optical bands, we recover the 7-d superorbital period initially discovered in X-rays, but we do not recover the orbital period. In the far-ultraviolet, we find evidence for a 27.2 min period (shorter than the 28.2 min period seen in X-rays). We find that either a neutron star or black hole could explain the observed properties of X9. We also perform binary evolution calculations, showing that the formation of an initial black hole/ He-star binary early in the life of a globular cluster could evolve into a present-day system such as X9 (should the compact object in this system indeed be a black hole) via mass-transfer driven by gravitational wave radiation.

Discovery of radio emission from the symbiotic X-ray binary system GX 1+4

Science.gov (United States)

van den Eijnden, J.; Degenaar, N.; Russell, T. D.; Miller-Jones, J. C. A.; Wijnands, R.; Miller, J. M.; King, A. L.; Rupen, M. P.

2018-02-01

We report the discovery of radio emission from the accreting X-ray pulsar and symbiotic X-ray binary GX 1+4 with the Karl G. Jansky Very Large Array. This is the first radio detection of such a system, wherein a strongly magnetized neutron star accretes from the stellar wind of an M-type giant companion. We measure a 9 GHz radio flux density of 105.3 ± 7.3 μJy, but cannot place meaningful constraints on the spectral index due to a limited frequency range. We consider several emission mechanisms that could be responsible for the observed radio source. We conclude that the observed properties are consistent with shocks in the interaction of the accretion flow with the magnetosphere, a synchrotron-emitting jet, or a propeller-driven outflow. The stellar wind from the companion is unlikely to be the origin of the radio emission. If the detected radio emission originates from a jet, it would show that strong magnetic fields (≥1012 G) do not necessarily suppress jet formation.

Mass loss from OB supergiants in x-ray binary systems

International Nuclear Information System (INIS)

Alme, M.L.; Wilson, J.R.

1975-01-01

A study of the atmospheres of OB supergiants in x-ray binary systems indicates that when the stellar surface is close enough to the saddle in the gravitational potential to provide a mass transfer rate adequate to power a compact x-ray source, large-amplitude variations in the rate of mass flow occur. 9 references

X-ray and Optical Explorations of Spiders

Science.gov (United States)

Roberts, M.; Al Noori, H.; Torres, R.; Russell, D.; Mclaughlin, M.; Gentile, P.

2017-10-01

Black widows and redbacks are binary systems consisting of a millisecond pulsar in a close binary with a companion which is having matter driven off of its surface by the pulsar wind. X-rays due to an intrabinary shock have been observed from many of these systems, as well as orbital variations in the optical emission from the companion due to heating and tidal distortion. We have been systematically studying these systems in radio, optical and X-rays. Here we will present an overview of X-ray and optical studies of these systems, including new XMM-Newton data obtained from several of these systems, along with new optical photometry.

Chandra reveals a black hole X-ray binary within the ultraluminous supernova remnant MF 16

Science.gov (United States)

Roberts, T. P.; Colbert, E. J. M.

2003-06-01

We present evidence, based on Chandra ACIS-S observations of the nearby spiral galaxy NGC 6946, that the extraordinary X-ray luminosity of the MF 16 supernova remnant actually arises in a black hole X-ray binary. This conclusion is drawn from the point-like nature of the X-ray source, its X-ray spectrum closely resembling the spectrum of other ultraluminous X-ray sources thought to be black hole X-ray binary systems, and the detection of rapid hard X-ray variability from the source. We briefly discuss the nature of the hard X-ray variability, and the origin of the extreme radio and optical luminosity of MF 16 in light of this identification.

THE CHANDRA X-RAY SURVEY OF PLANETARY NEBULAE (CHANPLANS): PROBING BINARITY, MAGNETIC FIELDS, AND WIND COLLISIONS

Energy Technology Data Exchange (ETDEWEB)

Kastner, J. H.; Montez, R. Jr.; Rapson, V. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Balick, B. [Department of Astronomy, University of Washington, Seattle, WA (United States); Frew, D. J.; De Marco, O.; Parker, Q. A. [Department of Physics and Astronomy and Macquarie Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney, NSW 2109 (Australia); Miszalski, B. [South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa); Sahai, R. [Jet Propulsion Laboratory, California Institute of Technology, MS 183-900, Pasadena, CA 91109 (United States); Blackman, E.; Frank, A. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Chu, Y.-H. [Department of Astronomy, University of Illinois, Champagne-Urbana, IL (United States); Guerrero, M. A. [Instituto de Astrofisica de Astronomia, Glorieta de la Astronomia s/n, Granada 18008 (Spain); Lopez, J. A. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Campus Ensenada, Apdo. Postal 22860, Ensenada, B. C. (Mexico); Zijlstra, A. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Behar, E. [Department of Physics, Technion (Israel); Bujarrabal, V. [Observatorio Astronomico Nacional, Apartado 112, E-28803, Alcala de Henares (Spain); Corradi, R. L. M. [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain); Nordhaus, J. [Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623 (United States); Sandin, C., E-mail: jhk@cis.rit.edu, E-mail: soker@physics.technion.ac.il, E-mail: eva.villaver@uam.es [Leibniz Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); and others

2012-08-15

We present an overview of the initial results from the Chandra Planetary Nebula Survey (CHANPLANS), the first systematic (volume-limited) Chandra X-Ray Observatory survey of planetary nebulae (PNe) in the solar neighborhood. The first phase of CHANPLANS targeted 21 mostly high-excitation PNe within {approx}1.5 kpc of Earth, yielding four detections of diffuse X-ray emission and nine detections of X-ray-luminous point sources at the central stars (CSPNe) of these objects. Combining these results with those obtained from Chandra archival data for all (14) other PNe within {approx}1.5 kpc that have been observed to date, we find an overall X-ray detection rate of {approx}70% for the 35 sample objects. Roughly 50% of the PNe observed by Chandra harbor X-ray-luminous CSPNe, while soft, diffuse X-ray emission tracing shocks-in most cases, 'hot bubbles'-formed by energetic wind collisions is detected in {approx}30%; five objects display both diffuse and point-like emission components. The presence (or absence) of X-ray sources appears correlated with PN density structure, in that molecule-poor, elliptical nebulae are more likely to display X-ray emission (either point-like or diffuse) than molecule-rich, bipolar, or Ring-like nebulae. All but one of the point-like CSPNe X-ray sources display X-ray spectra that are harder than expected from hot ({approx}100 kK) central stars emitting as simple blackbodies; the lone apparent exception is the central star of the Dumbbell nebula, NGC 6853. These hard X-ray excesses may suggest a high frequency of binary companions to CSPNe. Other potential explanations include self-shocking winds or PN mass fallback. Most PNe detected as diffuse X-ray sources are elliptical nebulae that display a nested shell/halo structure and bright ansae; the diffuse X-ray emission regions are confined within inner, sharp-rimmed shells. All sample PNe that display diffuse X-ray emission have inner shell dynamical ages {approx}< 5 Multiplication

A Comparison Between Spectral Properties of ULXs and Luminous X-ray Binaries

Science.gov (United States)

Berghea, C. T.; Colbert, E. J. M.; Roberts, T. P.

2004-05-01

What is special about the 1039 erg s-1 limit that is used to define the ULX class? We investigate this question by analyzing Chandra X-ray spectra of 71 X-ray bright point sources from nearby galaxies. Fifty-one of these sources are ULXs (LX(0.3-8.0 keV) ≥ 1039 erg s-1), and 20 sources (our comparison sample) are less-luminous X-ray binaries with LX(0.3-8.0 keV) = 1038-39 erg s-1. Our sample objects were selected from the Chandra archive to have ≥1000 counts and thus represent the highest quality spectra in the Chandra archives for extragalactic X-ray binaries and ULXs. We fit the spectra with one-component models (e.g., cold absorption with power-law, or cold absorption with multi-colored disk blackbody) and two-component models (e.g. absorption with both a power-law and a multi colored disk blackbody). A crude measure of the spectral states of the sources are determined observationally by calibrating the strength of the disk (blackbody) and coronal (power-law) components. These results are then use to determine if spectral properties of the ULXs are statistically distinct from those of the comparison objects, which are assumed to be ``normal'' black-hole X-ray binaries.

Simulating the X-ray luminosity of Be X-ray binaries: the case for black holes versus neutron stars

Science.gov (United States)

Brown, R. O.; Ho, W. C. G.; Coe, M. J.; Okazaki, A. T.

2018-04-01

There are over 100 Be stars that are known to have neutron star companions but only one such system with a black hole. Previous theoretical work suggests this is not due to their formation but due to differences in X-ray luminosity. It has also been proposed that the truncation of the Be star's circumstellar disc is dependent on the mass of the compact object. Hence, Be star discs in black hole binaries are smaller. Since accretion onto the compact object from the Be star's disc is what powers the X-ray luminosity, a smaller disc in black hole systems leads to a lower luminosity. In this paper, simulations are performed with a range of eccentricities and compact object mass. The disc's size and density are shown to be dependent on both quantities. Mass capture and, in turn, X-ray luminosity are heavily dependent on the size and density of the disc. Be/black hole binaries are expected to be up to ˜10 times fainter than Be/neutron star binaries when both systems have the same eccentricity and can be 100 times fainter when comparing systems with different eccentricity.

Chandra Discovers the X-ray Signature of a Powerful Wind from a Galactic Microquasar

Science.gov (United States)

2000-11-01

NASA's Chandra X-ray Observatory has detected, for the first time in X rays, a stellar fingerprint known as a P Cygni profile--the distinctive spectral signature of a powerful wind produced by an object in space. The discovery reveals a 4.5-million-mile-per-hour wind coming from a highly compact pair of stars in our galaxy, report researchers from Penn State and the Massachusetts Institute of Technology in a paper they will present on 8 November 2000 during a meeting of the High-Energy Astrophysics Division of the American Astronomical Society in Honolulu, Hawaii. The paper also has been accepted for publication in The Astrophysical Journal Letters. "To our knowledge, these are the first P Cygni profiles reported in X rays," say researchers Niel Brandt, assistant professor of astronomy and astrophysics at Penn State, and Norbert S. Schulz, research scientist at the Massachusetts Institute of Technology. The team made the discovery during their first observation of a binary-star system with the Chandra X-ray Observatory, which was launched into space in July 1999. The system, known as Circinus X-1, is located about 20,000 light years from Earth in the constellation Circinus near the Southern Cross. It contains a super-dense neutron star in orbit around a normal fusion-burning star like our Sun. Although Circinus X-1 was discovered in 1971, many properties of this system remain mysterious because Circinus X-1 lies in the galactic plane where obscuring dust and gas have blocked its effective study in many wavelengths. The P Cygni spectral profile, previously detected primarily at ultraviolet and optical wavelengths but never before in X rays, is the textbook tool astronomers rely on for probing stellar winds. The profile looks like the outline of a roller coaster, with one really big hill and valley in the middle, on a data plot with velocity on one axis and the flow rate of photons per second on the other. It is named after the famous star P Cygni, in which such

The X-Ray Luminosity Functions of Field Low-Mass X-Ray Binaries in Early-Type Galaxies: Evidence for a Stellar Age Dependence

Science.gov (United States)

Lehmer, B. D.; Berkeley, M.; Zezas, A.; Alexander, D. M.; Basu-Zych, A.; Bauer, F. E.; Brandt, W. N.; Fragos, T.; Hornschemeier, A. E.; Kalogera, V.;

Discovery of two eclipsing X-ray binaries in M 51

Science.gov (United States)

Wang, Song; Soria, Roberto; Urquhart, Ryan; Liu, Jifeng

2018-04-01

We discovered eclipses and dips in two luminous (and highly variable) X-ray sources in M 51. One (CXOM51 J132943.3+471135) is an ultraluminous supersoft source, with a thermal spectrum at a temperature of about 0.1 keV and characteristic blackbody radius of about 104 km. The other (CXOM51 J132946.1+471042) has a two-component spectrum with additional thermal-plasma emission; it approached an X-ray luminosity of 1039erg s-1 during outbursts in 2005 and 2012. From the timing of three eclipses in a series of Chandra observations, we determine the binary period (52.75 ± 0.63 hr) and eclipse fraction (22% ± 0.1%) of CXOM51 J132946.1+471042. We also identify a blue optical counterpart in archival Hubble Space Telescope images, consistent with a massive donor star (mass of ˜20-35M⊙). By combining the X-ray lightcurve parameters with the optical constraints on the donor star, we show that the mass ratio in the system must be M_2/M_1 ≳ 18, and therefore the compact object is most likely a neutron star (exceeding its Eddington limit in outburst). The general significance of our result is that we illustrate one method (applicable to high-inclination sources) of identifying luminous neutron star X-ray binaries, in the absence of X-ray pulsations or phase-resolved optical spectroscopy. Finally, we discuss the different X-ray spectral appearance expected from super-Eddington neutron stars and black holes at high viewing angles.

On the Weak-Wind Problem in Massive Stars: X-Ray Spectra Reveal a Massive Hot Wind in mu Columbae

Science.gov (United States)

Huenemoerder, David P.; Oskinova, Lidia M.; Ignace, Richard; Waldron, Wayne L.; Todt, Helge; Hamaguchi, Kenji; Kitamoto, Shunji

2012-01-01

Mu Columbae is a prototypical weak-wind O star for which we have obtained a high-resolution X-ray spectrum with the Chandra LETG/ACIS instrument and a low-resolution spectrum with Suzaku. This allows us, for the first time, to investigate the role of X-rays on the wind structure in a bona fide weak-wind system and to determine whether there actually is a massive hot wind. The X-ray emission measure indicates that the outflow is an order of magnitude greater than that derived from UV lines and is commensurate with the nominal wind-luminosity relationship for O stars. Therefore, the "weak-wind problem"--identified from cool wind UV/optical spectra--is largely resolved by accounting for the hot wind seen in X-rays. From X-ray line profiles, Doppler shifts, and relative strengths, we find that this weak-wind star is typical of other late O dwarfs. The X-ray spectra do not suggest a magnetically confined plasma-the spectrum is soft and lines are broadened; Suzaku spectra confirm the lack of emission above 2 keV. Nor do the relative line shifts and widths suggest any wind decoupling by ions. The He-like triplets indicate that the bulk of the X-ray emission is formed rather close to the star, within five stellar radii. Our results challenge the idea that some OB stars are "weak-wind" stars that deviate from the standard wind-luminosity relationship. The wind is not weak, but it is hot and its bulk is only detectable in X-rays.

X-ray Binaries in the Central Region of M31

Science.gov (United States)

Trudolyubov, Sergey P.; Priedhorsky, W. C.; Cordova, F. A.

2006-09-01

We present the results of the systematic survey of X-ray sources in the central region of M31 using the data of XMM-Newton observations. The spectral properties and variability of 124 bright X-ray sources were studied in detail. We found that more than 80% of sources observed in two or more observations show significant variability on the time scales of days to years. At least 50% of the sources in our sample are spectrally variable. The fraction of variable sources in our survey is much higher than previously reported from Chandra survey of M31, and is remarkably close to the fraction of variable sources found in M31 globular cluster X-ray source population. We present spectral distribution of M31 X-ray sources, based on the spectral fitting with a power law model. The distribution of spectral photon index has two main peaks at 1.8 and 2.3, and shows clear evolution with source luminosity. Based on the similarity of the properties of M31 X-ray sources and their Galactic counterparts, we expect most of X-ray sources in our sample to be accreting binary systems with neutron star and black hole primaries. Combining the results of X-ray analysis (X-ray spectra, hardness-luminosity diagrams and variability) with available data at other wavelengths, we explore the possibility of distinguishing between bright neutron star and black hole binary systems, and identify 7% and 25% of sources in our sample as a probable black hole and neutron star candidates. Finally, we compare the M31 X-ray source population to the source populations of normal galaxies of different morphological type. Support for this work was provided through NASA Grant NAG5-12390. Part of this work was done during a summer workshop ``Revealing Black Holes'' at the Aspen Center for Physics, S. T. is grateful to the Center for their hospitality.

GBM Observations of Be X-Ray Binary Outbursts

Science.gov (United States)

Wilson-Hodge, Colleen A.; Finger, M. H.; Jenke, P. A.

2014-01-01

Since 2008 we have been monitoring accreting pulsars using the Gamma ray Burst Monitor (GBM) on Fermi. This monitoring program includes daily blind full sky searches for previously unknown or previously quiescent pulsars and source specific analysis to track the frequency evolution of all detected pulsars. To date we have detected outbursts from 23 transient accreting pulsars, including 21 confirmed or likely Be/X-ray binaries. I will describe our techniques and highlight results for selected pulsars.

GAMMA-RAY SIGNAL FROM THE PULSAR WIND IN THE BINARY PULSAR SYSTEM PSR B1259-63/LS 2883

Energy Technology Data Exchange (ETDEWEB)

Khangulyan, Dmitry [Institute of Space and Astronautical Science/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Aharonian, Felix A. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Bogovalov, Sergey V. [National Research Nuclear University-MEPHI, Kashirskoe Shosse 31, Moscow 115409 (Russian Federation); Ribo, Marc, E-mail: khangul@astro.isas.jaxa.jp, E-mail: felix.aharonian@dias.ie, E-mail: svbogovalov@mephi.ru, E-mail: mribo@am.ub.es [Departament d' Astronomia i Meteorologia, Institut de Ciences del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E-08028 Barcelona (Spain)

2011-12-01

Binary pulsar systems emit potentially detectable components of gamma-ray emission due to Comptonization of the optical radiation of the companion star by relativistic electrons of the pulsar wind, both before and after termination of the wind. The recent optical observations of binary pulsar system PSR B1259-63/LS 2883 revealed radiation properties of the companion star which differ significantly from previous measurements. In this paper, we study the implications of these observations for the interaction rate of the unshocked pulsar wind with the stellar photons and the related consequences for fluxes of high energy and very high energy (VHE) gamma rays. We show that the signal should be strong enough to be detected with Fermi close to the periastron passage, unless the pulsar wind is strongly anisotropic or the Lorentz factor of the wind is smaller than 10{sup 3} or larger than 10{sup 5}. The higher luminosity of the optical star also has two important implications: (1) attenuation of gamma rays due to photon-photon pair production and (2) Compton drag of the unshocked wind. While the first effect has an impact on the light curve of VHE gamma rays, the second effect may significantly decrease the energy available for particle acceleration after termination of the wind.

X-RAY PROPERTIES OF YOUNG EARLY-TYPE GALAXIES. I. X-RAY LUMINOSITY FUNCTION OF LOW-MASS X-RAY BINARIES

International Nuclear Information System (INIS)

Kim, Dong-Woo; Fabbiano, Giuseppina

2010-01-01

We have compared the combined X-ray luminosity function (XLF) of low-mass X-ray binaries (LMXBs) detected in Chandra observations of young, post-merger elliptical galaxies with that of typical old elliptical galaxies. We find that the XLF of the 'young' sample does not present the prominent high-luminosity break at L X > 5 x 10 38 erg s -1 found in the old elliptical galaxy XLF. The 'young' and 'old' XLFs differ with a 3σ statistical significance (with a probability less than 0.2% that they derive from the same underlying parent distribution). Young elliptical galaxies host a larger fraction of luminous LMXBs (L X > 5 x 10 38 erg s -1 ) than old elliptical galaxies and the XLF of the young galaxy sample is intermediate between that of typical old elliptical galaxies and that of star-forming galaxies. This observational evidence may be related to the last major/minor mergers and the associated star formation.

A model of two-stream non-radial accretion for binary X-ray pulsars

International Nuclear Information System (INIS)

Lipunov, V.M.

1982-01-01

The general case of non-radial accretion is assumed to occur in real binary systems containing X-ray pulsars. The structure and the stability of the magnetosphere, the interaction between the magnetosphere and accreted matter, as well as evolution of neutron star in close binary system are examined within the framework of the two-stream model of nonradial accretion onto a magnetized neutron star. Observable parameters of X-ray pulsars are explained in terms of the model considered. (orig.)

Massive stars and X-ray pulsars

International Nuclear Information System (INIS)

Henrichs, H.

1982-01-01

This thesis is a collection of 7 separate articles entitled: long term changes in ultraviolet lines in γ CAS, UV observations of γ CAS: intermittent mass-loss enhancement, episodic mass loss in γ CAS and in other early-type stars, spin-up and spin-down of accreting neutron stars, an excentric close binary model for the X Persei system, has a 97 minute periodicity in 4U 1700-37/HD 153919 really been discovered, and, mass loss and stellar wind in massive X-ray binaries. (Articles 1, 2, 5, 6 and 7 have been previously published). The first three articles are concerned with the irregular mass loss in massive stars. The fourth critically reviews thoughts since 1972 on the origin of the changes in periodicity shown by X-ray pulsars. The last articles indicate the relation between massive stars and X-ray pulsars. (C.F.)

Maximum mass ratio of AM CVn-type binary systems and maximum white dwarf mass in ultra-compact X-ray binaries

Directory of Open Access Journals (Sweden)

Arbutina Bojan

2011-01-01

Full Text Available AM CVn-type stars and ultra-compact X-ray binaries are extremely interesting semi-detached close binary systems in which the Roche lobe filling component is a white dwarf transferring mass to another white dwarf, neutron star or a black hole. Earlier theoretical considerations show that there is a maximum mass ratio of AM CVn-type binary systems (qmax ≈ 2/3 below which the mass transfer is stable. In this paper we derive slightly different value for qmax and more interestingly, by applying the same procedure, we find the maximum expected white dwarf mass in ultra-compact X-ray binaries.

The Emerging Population of Pulsar Wind Nebulae in Hard X-rays

Science.gov (United States)

Mattana, F.; Götz, D.; Terrier, R.; Renaud, M.; Falanga, M.

2009-05-01

The hard X-ray synchrotron emission from Pulsar Wind Nebulae probes energetic particles, closely related to the pulsar injection power at the present time. INTEGRAL has disclosed the yet poorly known population of hard X-ray pulsar/PWN systems. We summarize the properties of the class, with emphasys on the first hard X-ray bow-shock (CTB 80 powered by PSR B1951+32), and highlight some prospects for the study of Pulsar Wind Nebulae with the Simbol-X mission.

SELF-REGULATED SHOCKS IN MASSIVE STAR BINARY SYSTEMS

International Nuclear Information System (INIS)

Parkin, E. R.; Sim, S. A.

2013-01-01

In an early-type, massive star binary system, X-ray bright shocks result from the powerful collision of stellar winds driven by radiation pressure on spectral line transitions. We examine the influence of the X-rays from the wind-wind collision shocks on the radiative driving of the stellar winds using steady-state models that include a parameterized line force with X-ray ionization dependence. Our primary result is that X-ray radiation from the shocks inhibits wind acceleration and can lead to a lower pre-shock velocity, and a correspondingly lower shocked plasma temperature, yet the intrinsic X-ray luminosity of the shocks, L X , remains largely unaltered, with the exception of a modest increase at small binary separations. Due to the feedback loop between the ionizing X-rays from the shocks and the wind driving, we term this scenario as self-regulated shocks. This effect is found to greatly increase the range of binary separations at which a wind-photosphere collision is likely to occur in systems where the momenta of the two winds are significantly different. Furthermore, the excessive levels of X-ray ionization close to the shocks completely suppress the line force, and we suggest that this may render radiative braking less effective. Comparisons of model results against observations reveal reasonable agreement in terms of log (L X /L bol ). The inclusion of self-regulated shocks improves the match for kT values in roughly equal wind momenta systems, but there is a systematic offset for systems with unequal wind momenta (if considered to be a wind-photosphere collision).

Searching for Exoplanets around X-Ray Binaries with Accreting White Dwarfs, Neutron Stars, and Black Holes

Science.gov (United States)

Imara, Nia; Di Stefano, Rosanne

2018-05-01

We recommend that the search for exoplanets around binary stars be extended to include X-ray binaries (XRBs) in which the accretor is a white dwarf, neutron star, or black hole. We present a novel idea for detecting planets bound to such mass transfer binaries, proposing that the X-ray light curves of these binaries be inspected for signatures of transiting planets. X-ray transits may be the only way to detect planets around some systems, while providing a complementary approach to optical and/or radio observations in others. Any planets associated with XRBs must be in stable orbits. We consider the range of allowable separations and find that orbital periods can be hours or longer, while transit durations extend upward from about a minute for Earth-radius planets, to hours for Jupiter-radius planets. The search for planets around XRBs could begin at once with existing X-ray observations of these systems. If and when a planet is detected around an X-ray binary, the size and mass of the planet may be readily measured, and it may also be possible to study the transmission and absorption of X-rays through its atmosphere. Finally, a noteworthy application of our proposal is that the same technique could be used to search for signals from extraterrestrial intelligence. If an advanced exocivilization placed a Dyson sphere or similar structure in orbit around the accretor of an XRB in order to capture energy, such an artificial structure might cause detectable transits in the X-ray light curve.

A 3D dynamical model of the colliding winds in binary systems

Science.gov (United States)

Parkin, E. R.; Pittard, J. M.

2008-08-01

We present a three-dimensional (3D) dynamical model of the orbital-induced curvature of the wind-wind collision region in binary star systems. Momentum balance equations are used to determine the position and shape of the contact discontinuity between the stars, while further downstream the gas is assumed to behave ballistically. An Archimedean spiral structure is formed by the motion of the stars, with clear resemblance to high-resolution images of the so-called `pinwheel nebulae'. A key advantage of this approach over grid or smoothed particle hydrodynamic models is its significantly reduced computational cost, while it also allows the study of the structure obtained in an eccentric orbit. The model is relevant to symbiotic systems and γ-ray binaries, as well as systems with O-type and Wolf-Rayet stars. As an example application, we simulate the X-ray emission from hypothetical O+O and WR+O star binaries, and describe a method of ray tracing through the 3D spiral structure to account for absorption by the circumstellar material in the system. Such calculations may be easily adapted to study observations at wavelengths ranging from the radio to γ-ray.

X-RAY STUDIES OF THE BLACK WIDOW PULSAR PSR B1957+20

International Nuclear Information System (INIS)

Huang, R. H. H.; Kong, A. K. H.; Takata, J.; Cheng, K. S.; Hui, C. Y.; Lin, L. C. C.

2012-01-01

We report on Chandra observations of the black widow pulsar, PSR B1957+20. Evidence for a binary-phase dependence of the X-ray emission from the pulsar is found with a deep observation. The binary-phase-resolved spectral analysis reveals non-thermal X-ray emission of PSR B1957+20, confirming the results of previous studies. This suggests that the X-rays are mostly due to intra-binary shock emission, which is strongest when the pulsar wind interacts with the ablated material from the companion star. The geometry of the peak emission is determined in our study. The marginal softening of the spectrum of the non-thermal X-ray tail may indicate that particles injected at the termination shock are dominated by synchrotron cooling.

X-Ray Timing Analysis of Cyg X-3 Using AstroSat/LAXPC: Detection of Milli-hertz Quasi-periodic Oscillations during the Flaring Hard X-Ray State

Energy Technology Data Exchange (ETDEWEB)

Pahari, Mayukh; Misra, Ranjeev [Inter-University Center for Astronomy and Astrophysics, Ganeshkhind, Pune 411007 (India); Antia, H M; Yadav, J S; Chauhan, Jai Verdhan; Chitnis, V R; Dedhia, Dhiraj; Katoch, Tilak; Madhwani, P; Shah, Parag [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Agrawal, P C [UM-DAE Center of Excellence for Basic Sciences, University of Mumbai, Kalina, Mumbai 400098 (India); Manchanda, R K [University of Mumbai, Kalina, Mumbai 400098 (India); Paul, B, E-mail: mayukh@iucaa.in [Department of Astronomy and Astrophysics, Raman Research Institute, Bengaluru 560080 (India)

2017-11-01

We present here results from the X-ray timing and spectral analysis of the X-ray binary Cyg X-3 using observations from the Large Area X-ray proportional Counter on board AstroSat . Consecutive light curves observed over a period of one year show the binary orbital period of 17253.56 ± 0.19 s. Another low-amplitude, slow periodicity of the order of 35.8 ± 1.4 days is observed, which may be due to the orbital precession as suggested earlier by Molteni et al. During the rising binary phase, power density spectra from different observations during the flaring hard X-ray state show quasi-periodic oscillations (QPOs) at ∼5–8 mHz, ∼12–14 mHz, and ∼18–24 mHz frequencies at the minimum confidence of 99%. However, during the consecutive binary decay phase, no QPO is detected up to 2 σ significance. Energy-dependent time-lag spectra show soft lag (soft photons lag hard photons) at the mHz QPO frequency and the fractional rms of the QPO increases with the photon energy. During the binary motion, the observation of mHz QPOs during the rising phase of the flaring hard state may be linked to the increase in the supply of the accreting material in the disk and corona via stellar wind from the companion star. During the decay phase, the compact source moves in the outer wind region causing the decrease in supply of material for accretion. This may cause weakening of the mHz QPOs below the detection limit. This is also consistent with the preliminary analysis of the orbital phase-resolved energy spectra presented in this paper.

ORBITAL VARIATION OF THE X-RAY EMISSION FROM THE DOUBLE NEUTRON STAR BINARY J1537+1155

International Nuclear Information System (INIS)

Durant, Martin; Kargaltsev, Oleg; Volkov, Igor; Pavlov, George G.

2011-01-01

We observed the double neutron star binary (DNSB) containing PSR J1537+1155 (also known as B1534+12) with the Chandra X-Ray Observatory. This is one of the two DNSBs detected in X-rays and the only one where a hint of variability with orbital phase was found (in the previous Chandra observation). Our follow-up observation supports the earlier result: the distribution of photon arrival times with orbital phase again shows a deficit around apastron. The significance of the deficit in the combined data set exceeds 99%. Such an orbital light curve suggests that the X-ray emission is seen only when neutron star (NS) B passes through the equatorial pulsar wind of NS A. We describe statistical tests that we used to determine the significance of the deficit, and conclusions that can be drawn from its existence, such as interaction of the pulsar wind with the NS companion. We also provide better constrained spectral model parameters obtained from the joint spectral fits to the data from both observations. A power law successfully fits the data, with best-fit photon index Γ = 3.1 ± 0.4 and unabsorbed flux f = (3.2 ± 0.8) × 10 –15 erg s –1 cm –2 (0.3-8 keV range).

SELF-REGULATED SHOCKS IN MASSIVE STAR BINARY SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Parkin, E. R.; Sim, S. A., E-mail: parkin@mso.anu.edu.au, E-mail: s.sim@qub.ac.uk [Research School of Astronomy and Astrophysics, Australian National University, ACT 2611 (Australia)

2013-04-20

In an early-type, massive star binary system, X-ray bright shocks result from the powerful collision of stellar winds driven by radiation pressure on spectral line transitions. We examine the influence of the X-rays from the wind-wind collision shocks on the radiative driving of the stellar winds using steady-state models that include a parameterized line force with X-ray ionization dependence. Our primary result is that X-ray radiation from the shocks inhibits wind acceleration and can lead to a lower pre-shock velocity, and a correspondingly lower shocked plasma temperature, yet the intrinsic X-ray luminosity of the shocks, L{sub X}, remains largely unaltered, with the exception of a modest increase at small binary separations. Due to the feedback loop between the ionizing X-rays from the shocks and the wind driving, we term this scenario as self-regulated shocks. This effect is found to greatly increase the range of binary separations at which a wind-photosphere collision is likely to occur in systems where the momenta of the two winds are significantly different. Furthermore, the excessive levels of X-ray ionization close to the shocks completely suppress the line force, and we suggest that this may render radiative braking less effective. Comparisons of model results against observations reveal reasonable agreement in terms of log (L{sub X}/L{sub bol}). The inclusion of self-regulated shocks improves the match for kT values in roughly equal wind momenta systems, but there is a systematic offset for systems with unequal wind momenta (if considered to be a wind-photosphere collision).

Wind accretion and formation of disk structures in symbiotic binary systems

Science.gov (United States)

de Val-Borro, M.; Karovska, M.; Sasselov, D. D.; Stone, J. M.

2015-05-01

We investigate gravitationally focused wind accretion in binary systems consisting of an evolved star with a gaseous envelope and a compact accreting companion. We study the mass accretion and formation of an accretion disk around the secondary caused by the strong wind from the primary late-type component using global 2D and 3D hydrodynamic numerical simulations. In particular, the dependence of the mass accretion rate on the mass loss rate, wind temperature and orbital parameters of the system is considered. For a typical slow and massive wind from an evolved star the mass transfer through a focused wind results in rapid infall onto the secondary. A stream flow is created between the stars with accretion rates of a 2--10% percent of the mass loss from the primary. This mechanism could be an important method for explaining periodic modulations in the accretion rates for a broad range of interacting binary systems and fueling of a large population of X-ray binary systems. We test the plausibility of these accretion flows indicated by the simulations by comparing with observations of the symbiotic variable system CH Cyg.

More surprises from the violent gamma-ray binary LS 2883 /B1259-63.

Science.gov (United States)

Kargaltsev, Oleg; Hare, Jeremy; Pavlov, George G.

2018-01-01

We report the results of a Chandra X-ray Observatory (CXO) monitoring campaign of the high-mass gamma-ray binary LS 2883, which hosts the young pulsar B1259-63. The monitoring now covers two binary cycles (6.8 years) and allows us to conclude that ejections of high-velocity X-ray emitting material are common for this binary. In the first cycle we observed an extended feature which detached and moved away from the binary. The observed changes in position were consistent with a steady motion with v=(0.07+/-0.01)c and a slight hint of acceleration. Tracing the motion back in time suggested that the X-ray emitting matter was ejected close to periastron passage. In the last orbital cycle, accelerated motion (reaching (0.13+/-0.02)c) is strongly preferred over a steady motion (the latter would imply that the ejected material was launched ~400 days after the periastron passage). The moving feature is also more luminous, compared to the previous binary cycle, larger in its apparent extent, and exhibits a puzzling morphology. We will show the CXO movies from both binary cycles and discuss physical interpretation of the resolved outflow dynamics in this remarkable system, which provides unique insight into the properties of the pulsar and stellar winds and their interaction.

Unusual Black Hole Binary LMC X-3: A Transient High-Mass X-Ray Binary That Is Almost Always On?

Science.gov (United States)

Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A.

2017-01-01

We have analyzed a rich, multimission, multiwavelength data set from the black hole X-ray binary (BHXB) LMC X-3, covering a new anomalous low state (ALS), during which the source flux falls to an unprecedentedly low and barely detectable level, and a more normal low state. Simultaneous X-ray and UV/optical monitoring data from Swift are combined with pointed observations from the Rossi X-ray Timing Explorer (RXTE) and X-ray Multi- Mirror Mission (XMM-Newton) and light curves from the Monitor of All-Sky X-ray Image (MAXI) instrument to compare the source characteristics during the ALS with those seen during the normal low state. An XMM-Newton spectrum obtained during the ALS can be modeled using an absorbed power law with Gamma = 1.41‚+/- 0.65 and a luminosity of 7.97 x 10(exp 33) erg/s (0.6-5 keV). The Swift X-ray and UV light curves indicate an X-ray lag of approx. 8 days as LMC X-3 abruptly exits the ALS, suggesting that changes in the mass accretion rate from the donor drive the X-ray lag. The normal low state displays an asymmetric profile in which the exit occurs more quickly than the entry, with minimum X-ray flux a factor of approx. 4300 brighter than during the ALS. The UV brightness of LMC X-3 in the ALS is also fainter and less variable than during normal low states. The existence of repeated ALSs in LMC X-3, as well as a comparison with other BHXBs, implies that it is very close to the transient/persistent X-ray source dividing line. We conclude that LMC X-3 is a transient source that is almost always "on."

Suzaku observation of the eclipsing high mass X-ray binary pulsar XTE J1855-026

Science.gov (United States)

Devasia, Jincy; Paul, Biswajit

2018-02-01

We report results from analysis performed on an eclipsing supergiant high mass X-ray binary pulsar XTE J1855-026 observed with the X-ray Imaging Spectrometer (XIS) on-board Suzaku Observatory in April 2015. Suzaku observed this source for a total effective exposure of ˜ 87 ks just before an eclipse. Pulsations are clearly observed and the pulse profiles of XTE J1855-026 did not show significant energy dependence during this observation consistent with previous reports. The time averaged energy spectrum of XTE J1855-026 in the 1.0-10.5 keV energy range can be well fitted with a partial covering power law model modified with interstellar absorption along with a black-body component for soft excess and a gaussian for iron fluorescence line emision. The hardness ratio evolution during this observation indicated significant absorption of soft X-rays in some segments of the observation. For better understanding of the reason behind this, we performed time-resolved spectroscopy in the 2.5-10.5 keV energy band which revealed significant variations in the spectral parameters, especially the hydrogen column density and iron line equivalent width with flux. The correlated variations in the spectral parameters indicate towards the presence of clumps in the stellar wind of the companion star accounting for the absorption of low energy X-rays in some time segments.

Wind-driven angular momentum loss in binary systems. I - Ballistic case

Science.gov (United States)

Brookshaw, Leigh; Tavani, Marco

1993-01-01

We study numerically the average loss of specific angular momentum from binary systems due to mass outflow from one of the two stars for a variety of initial injection geometries and wind velocities. We present results of ballistic calculations in three dimensions for initial mass ratios q of the mass-losing star to primary star in the range q between 10 exp -5 and 10. We consider injection surfaces close to the Roche lobe equipotential surface of the mass-losing star, and also cases with the mass-losing star underfilling its Roche lobe. We obtain that the orbital period is expected to have a negative time derivative for wind-driven secular evolution of binaries with q greater than about 3 and with the mass-losing star near filling its Roche lobe. We also study the effect of the presence of an absorbing surface approximating an accretion disk on the average final value of the specific angular momentum loss. We find that the effect of an accretion disk is to increase the wind-driven angular momentum loss. Our results are relevant for evolutionary models of high-mass binaries and low-mass X-ray binaries.

Modelling the effect of absorption from the interstellar medium on transient black hole X-ray binaries

Science.gov (United States)

Eckersall, A. J.; Vaughan, S.; Wynn, G. A.

2017-10-01

All observations of Galactic X-ray binaries are affected by absorption from gas and dust in the interstellar medium (ISM) which imprints narrow (line) and broad (photoelectric edges) features on the continuum emission spectrum of the binary. Any spectral model used to fit data from a Galactic X-ray binary must therefore take account of these features; when the absorption is strong (as for most Galactic sources) it becomes important to accurately model the ISM absorption in order to obtain unbiased estimates of the parameters of the (emission) spectrum of the binary system. In this paper, we present analysis of some of the best spectroscopic data from the XMM-Newton RGS instrument using the most up-to-date photoabsorption model of the gaseous ISM ISMabs. We calculate column densities for H, O, Ne and Fe for seven transient black hole X-ray binary systems. We find that the hydrogen column densities in particular can vary greatly from those presented elsewhere in the literature. We assess the impact of using inaccurate column densities and older X-ray absorption models on spectral analysis using simulated data. We find that poor treatment of absorption can lead to large biases in inferred disc properties and that an independent analysis of absorption parameters can be used to alleviate such issues.

Neutron Stars in X-ray Binaries and their Environments

Indian Academy of Sciences (India)

Biswajit Paul

2017-09-07

Sep 7, 2017 ... Various recent studies of reprocessing of X-rays in the accretion disk surface .... accretion rate is considered to be the only variable fac- tor that determines ... stellar wind, and any intervening interstellar mate- rial. Reprocessed ...

Polarimetric observations of the innermost regions of relativistic jets in X-ray binaries

Directory of Open Access Journals (Sweden)

Russell D.M.

2013-12-01

Full Text Available Synchrotron emission from the relativistic jets launched close to black holes and neutron stars can be highly linearly polarized, depending on the configuration of the magnetic field. In X-ray binaries, optically thin synchrotron emission from the compact jets resides at infrared–optical wavelengths. The polarimetric signature of the jets is detected in the infrared and is highly variable in some X-ray binaries. This reveals the magnetic geometry in the compact jet, in a region close enough to the black hole that it is influenced by its strong gravity. In some cases the magnetic field is turbulent and variable near the jet base. In Cyg X–1, the origin of the γ-ray, X-ray and some of the infrared polarization is likely the optically thin synchrotron power law from the inner regions of the jet. In order to reproduce the polarization properties, the magnetic field in this region must be highly ordered, in contrast to other sources.

Long-term activity of two ultra-compact X-ray binaries

Czech Academy of Sciences Publication Activity Database

Šimon, Vojtěch

2004-01-01

Roč. 132, - (2004), s. 656-659 ISSN 0920-5632. [BeppoSAX Conference /2./. Amsterdam, 05.05.2003-08.05.2003] Institutional research plan: CEZ:AV0Z1003909 Keywords : neutron stars * X-rays * close binaries Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.944, year: 2004

OBSERVATIONS OF THE HIGH-MASS X-RAY BINARY A 0535+26 IN QUIESCENCE

International Nuclear Information System (INIS)

Rothschild, Richard; Markowitz, Alex; Hemphill, Paul; Caballero, Isabel; Pottschmidt, Katja; Kühnel, Matthias; Wilms, Jörn; Fürst, Felix; Doroshenko, Victor; Camero-Arranz, Ascension

2013-01-01

We have analyzed three observations of the high-mass X-ray binary A 0535+26 performed by the Rossi X-Ray Timing Explorer (RXTE) three, five, and six months after the last outburst in 2011 February. We detect pulsations only in the second observation. The 3-20 keV spectra can be fit equally well with either an absorbed power law or absorbed thermal bremsstrahlung model. Reanalysis of two earlier RXTE observations made 4 yr after the 1994 outburst, original BeppoSAX observations 2 yr later, reanalysis of four EXOSAT observations made 2 yr after the last 1984 outburst, and a recent XMM-Newton observation in 2012 reveal a stacked, quiescent flux level decreasing from ∼2 to –11 erg cm –2 s –1 over 6.5 yr after outburst. The detection of pulsations during half of the quiescent observations would imply that accretion onto the magnetic poles of the neutron star continues despite the fact that the circumstellar disk may no longer be present. The accretion could come from material built up at the corotation radius or from an isotropic stellar wind.

OBSERVATIONS OF THE HIGH-MASS X-RAY BINARY A 0535+26 IN QUIESCENCE

Energy Technology Data Exchange (ETDEWEB)

Rothschild, Richard; Markowitz, Alex; Hemphill, Paul [University of California, San Diego, Center for Astrophysics and Space Sciences, 9500 Gilman Dr., La Jolla, CA 92093-0424 (United States); Caballero, Isabel [CEA Saclay, DSM/IRFU/SAp -UMR AIM (7158) CNRS/CEA/Universite P. Diderot, Orme des Merisiers, Bat. 709, F-91191 Gif-sur-Yvette (France); Pottschmidt, Katja [CRESST, UMBC, and NASA GSFC, Code 661, Greenbelt, MD 20771 (United States); Kuehnel, Matthias; Wilms, Joern [Dr. Karl-Remeis-Sternwarte and ECAP, Sternwartstr. 7, D-96049 Bamberg (Germany); Fuerst, Felix [Space Radiation Lab, MC 290-17 Cahill, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125 (United States); Doroshenko, Victor [Institut fuer Astronomie und Astrophysik, Universitaet Tuebingen, Sand 1, D-72076 Tuebingen (Germany); Camero-Arranz, Ascension, E-mail: rrothschild@ucsd.edu [Institut de Ciencies de l' Espai, (IEEC-CSIC), Campus UAB, Fac. de Ciencies, Torre C5, parell, 2a planta, E-08193 Barcelona (Spain)

2013-06-10

We have analyzed three observations of the high-mass X-ray binary A 0535+26 performed by the Rossi X-Ray Timing Explorer (RXTE) three, five, and six months after the last outburst in 2011 February. We detect pulsations only in the second observation. The 3-20 keV spectra can be fit equally well with either an absorbed power law or absorbed thermal bremsstrahlung model. Reanalysis of two earlier RXTE observations made 4 yr after the 1994 outburst, original BeppoSAX observations 2 yr later, reanalysis of four EXOSAT observations made 2 yr after the last 1984 outburst, and a recent XMM-Newton observation in 2012 reveal a stacked, quiescent flux level decreasing from {approx}2 to <1 Multiplication-Sign 10{sup -11} erg cm{sup -2} s{sup -1} over 6.5 yr after outburst. The detection of pulsations during half of the quiescent observations would imply that accretion onto the magnetic poles of the neutron star continues despite the fact that the circumstellar disk may no longer be present. The accretion could come from material built up at the corotation radius or from an isotropic stellar wind.

Hard state neutron star and black hole X-ray binaries in the radio:X-ray luminosity plane

Science.gov (United States)

Gallo, Elena; Degenaar, Nathalie; van den Eijnden, Jakob

2018-05-01

Motivated by the large body of literature around the phenomenological properties of accreting black hole (BH) and neutron star (NS) X-ray binaries in the radio:X-ray luminosity plane, we carry out a comparative regression analysis on 36 BHs and 41 NSs in hard X-ray states, with data over 7 dex in X-ray luminosity for both. The BHs follow a radio to X-ray (logarithmic) luminosity relation with slope β = 0.59 ± 0.02, consistent with the NSs' slope (β =0.44^{+0.05}_{-0.04}) within 2.5σ. The best-fitting intercept for the BHs significantly exceeds that for the NSs, cementing BHs as more radio loud, by a factor ˜22. This discrepancy can not be fully accounted for by the mass or bolometric correction gap, nor by the NS boundary layer contribution to the X-rays, and is likely to reflect physical differences in the accretion flow efficiency, or the jet powering mechanism. Once importance sampling is implemented to account for the different luminosity distributions, the slopes of the non-pulsating and pulsating NS subsamples are formally inconsistent (>3σ), unless the transitional millisecond pulsars (whose incoherent radio emission mechanism is not firmly established) are excluded from the analysis. We confirm the lack of a robust partitioning of the BH data set into separate luminosity tracks.

A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy

Science.gov (United States)

Hailey, Charles J.; Mori, Kaya; Bauer, Franz E.; Berkowitz, Michael E.; Hong, Jaesub; Hord, Benjamin J.

2018-04-01

The existence of a ‘density cusp’—a localized increase in number—of stellar-mass black holes near a supermassive black hole is a fundamental prediction of galactic stellar dynamics. The best place to detect such a cusp is in the Galactic Centre, where the nearest supermassive black hole, Sagittarius A*, resides. As many as 20,000 black holes are predicted to settle into the central parsec of the Galaxy as a result of dynamical friction; however, so far no density cusp of black holes has been detected. Low-mass X-ray binary systems that contain a stellar-mass black hole are natural tracers of isolated black holes. Here we report observations of a dozen quiescent X-ray binaries in a density cusp within one parsec of Sagittarius A*. The lower-energy emission spectra that we observed in these binaries is distinct from the higher-energy spectra associated with the population of accreting white dwarfs that dominates the central eight parsecs of the Galaxy. The properties of these X-ray binaries, in particular their spatial distribution and luminosity function, suggest the existence of hundreds of binary systems in the central parsec of the Galaxy and many more isolated black holes. We cannot rule out a contribution to the observed emission from a population (of up to about one-half the number of X-ray binaries) of rotationally powered, millisecond pulsars. The spatial distribution of the binary systems is a relic of their formation history, either in the stellar disk around Sagittarius A* (ref. 7) or through in-fall from globular clusters, and constrains the number density of sources in the modelling of gravitational waves from massive stellar remnants, such as neutron stars and black holes.

The peculiar galactic center neutron star X-ray binary XMM J174457-2850.3

Energy Technology Data Exchange (ETDEWEB)

Degenaar, N.; Reynolds, M. T.; Miller, J. M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Wijnands, R. [Anton Pannekoek Institute of Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Altamirano, D. [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Kennea, J. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Gehrels, N. [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Haggard, D. [CIERA, Physics and Astronomy Department, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Ponti, G., E-mail: degenaar@umich.edu [Max Planck Institute fur Extraterrestriche Physik, D-85748 Garching (Germany)

2014-09-10

The recent discovery of a millisecond radio pulsar experiencing an accretion outburst similar to those seen in low mass X-ray binaries, has opened up a new opportunity to investigate the evolutionary link between these two different neutron star manifestations. The remarkable X-ray variability and hard X-ray spectrum of this object can potentially serve as a template to search for other X-ray binary/radio pulsar transitional objects. Here we demonstrate that the transient X-ray source XMM J174457-2850.3 near the Galactic center displays similar X-ray properties. We report on the detection of an energetic thermonuclear burst with an estimated duration of ≅2 hr and a radiated energy output of ≅ 5 × 10{sup 40} erg, which unambiguously demonstrates that the source harbors an accreting neutron star. It has a quiescent X-ray luminosity of L {sub X} ≅ 5 × 10{sup 32}(D/6.5 kpc){sup 2} erg s{sup –1} and exhibits occasional accretion outbursts during which it brightens to L {sub X} ≅ 10{sup 35}-10{sup 36}(D/6.5 kpc){sup 2} erg s{sup –1} for a few weeks (2-10 keV). However, the source often lingers in between outburst and quiescence at L {sub X} ≅ 10{sup 33}-10{sup 34}(D/6.5 kpc){sup 2} erg s{sup –1}. This peculiar X-ray flux behavior and its relatively hard X-ray spectrum, a power law with an index of Γ ≅ 1.4, could possibly be explained in terms of the interaction between the accretion flow and the magnetic field of the neutron star.

Non-conservative mass exchange and origin of X-ray close binaries

International Nuclear Information System (INIS)

Sugimoto, D.; Miyaji, S.

1980-01-01

There are two distinct types of XCBS. The Type I XCBS consists of an X-ray star and an early type star more massive than about 12 solar masses. On the contrary, the Type II XCBS consists of an X-ray star and a star less massive than about 2 solar masses. The aim of the present paper lies in interpreting the origin of these types of XCBS on the bases of the conditions for the formation of a neutron star and of mass exchange in close binary systems. (Auth.)

The X-ray Variability of Eta Car, 1996-2010

Science.gov (United States)

Corcoran, Michael F.; Hamaguchi, K.; Gull, T.; Owocki, S.; Pittard, J.

2010-01-01

X-ray photometry in the 2-10 keY band of the the supermassive binary star Eta Car has been measured with the Rossi X-ray Timing Explorer from 1996-2010. The ingress to X-ray minimum is consistent with a period of 2024 days. The 2009 X-ray minimum began on January 162009 and showed an unexpectedly abrupt recovery starting after 12 Feb 2009. The X-ray colors become harder about half-way through all three minima and continue until flux recovery. The behavior of the fluxes and X-ray colors for the most recent X-ray minimum, along with Chandra high resolution grating spectra at key phases suggests a significant change in the inner wind of Eta Car, a possible indicator that the star is entering a new unstable phase of mass loss.

Close binary star type x-ray star and its mechanism of radiation

Energy Technology Data Exchange (ETDEWEB)

Hoshi, R [Rikkyo Univ., Tokyo (Japan). Dept. of Physics

1975-09-01

Recent progress of the study of an X-ray star is described. In 1970, the periodical emission of pulsed X-rays from Cen X-3 and Her X-1 was observed. An optically corresponding celestial object for the Cen X-3 was reported in 1973, and the mass of Cen X-3 was revised. The optical object was named after Krzeminsky. From the observed variation of luminosity, it is said that the Krzeminsky's star is deformed. This fact gave new data on the mass of the Cen X-3, and the mass is several times as large as the previously estimated value. The behavior of the Her X-1 shows four kinds of clear time variation, and indicates the characteristics of an X-ray star. The Her X-1 is an X-ray pulser the same as Cen X-3, and is a close binary star. The opposite star is known as HZ-Her, and shows weaker luminosity than the intensity of X-ray from the Her X-1. Thirty-five day period was seen in the intensity variation of X-ray. The mechanism of X-ray pulsing can be explained by material flow into a neutron star. The energy spectrum from Her X-1 is different from that from the Cen X-3. Another X-ray star, Cyg X-1, is considered to be a black hole from its X-ray spectrum.

X-Ray and Optical Observations of the Unique Binary System HD 49798/RX J0648.0-4418

Science.gov (United States)

Mereghetti, S.; La Palombara, N.; Tiengo, A.; Pizzolato, F.; Esposito, P.; Woudt, P. A.; Israel, G. L.; Stella, L.

2011-08-01

We report the results of XMM-Newton observations of HD 49798/RX J0648.0-4418, the only known X-ray binary consisting of a hot sub-dwarf and a white dwarf. The white dwarf rotates very rapidly (P = 13.2 s) and has a dynamically measured mass of 1.28 ± 0.05 M sun. Its X-ray emission consists of a strongly pulsed, soft component, well fit by a blackbody with kT BB ~ 40 eV, accounting for most of the luminosity, and a fainter hard power-law component (photon index ~1.6). A luminosity of ~1032 erg s-1 is produced by accretion onto the white dwarf of the helium-rich matter from the wind of the companion, which is one of the few hot sub-dwarfs showing evidence of mass loss. A search for optical pulsations at the South African Astronomical Observatory 1.9 m telescope gave negative results. X-rays were also detected during the white dwarf eclipse. This emission, with luminosity 2 × 1030 erg s-1, can be attributed to HD 49798 and represents the first detection of a hot sub-dwarf star in the X-ray band. HD 49798/RX J0648.0-4418 is a post-common-envelope binary which most likely originated from a pair of stars with masses ~8-10 M sun. After the current He-burning phase, HD 49798 will expand and reach the Roche lobe, causing a higher accretion rate onto the white dwarf which can reach the Chandrasekhar limit. Considering the fast spin of the white dwarf, this could lead to the formation of a millisecond pulsar. Alternatively, this system could be a Type Ia supernova progenitor with the appealing characteristic of a short time delay, being the descendent of relatively massive stars.

Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni During Quiescence

Science.gov (United States)

Rana, Vikram; Loh, Alan; Corbel, Stephane; Tomsick, John A.; Chakrabarty, Deepto; Walton, Dominic J.; Barret, Didier; Boggs, Steven E.; Christensen, Finn E.; Craig, William;

THE CONTRIBUTION OF X-RAY BINARIES TO THE EVOLUTION OF LATE-TYPE GALAXIES: EVOLUTIONARY POPULATION SYNTHESIS SIMULATIONS

International Nuclear Information System (INIS)

Zuo Zhaoyu; Li Xiangdong

2011-01-01

X-ray studies of normal late-type galaxies have shown that non-nuclear X-ray emission is typically dominated by X-ray binaries and provides a useful measure of star formation activity. We have modeled the X-ray evolution of late-type galaxies over the ∼14 Gyr of cosmic history, with an evolutionary population synthesis code developed by Hurley et al. Our calculations reveal a decrease in the X-ray luminosity-to-mass ratio L X /M with time, in agreement with observations. We show that this decrease is a natural consequence of stellar and binary evolution and the mass accumulating process in galaxies. The X-ray-to-optical luminosity ratio L X /L B is found to be fairly constant (around ∼10 30 erg s -1 L -1 B,sun ) and insensitive to the star formation history in the galaxies. The nearly constant value of L X /L B is in conflict with the observed increase in L X /L B from z = 0 to 1.4. The discrepancy may be caused by intense obscured star formation activity that leads to a nonlinear relationship between X-ray and B-band emission.

Soft X-ray production by photon scattering in pulsating binary neutron star sources

International Nuclear Information System (INIS)

Bussard, R.W.; Meszaros, P.; Alexander, S.

1985-01-01

A new mechanism is proposed as a source of soft (less than 1 keV) radiation in binary pulsating X-ray sources, in the form of photon scattering which leaves the electron in an excited Landau level. In a plasma with parameters typical of such sources, the low-energy X-ray emissivity of this mechanism far exceeds that of bremsstrahlung. This copious source of soft photons is quite adequate to provide the seed photons needed to explain the power-law hard X-ray spectrum by inverse Comptonization on the hot electrons at the base of the accretion column. 13 references

Rotation of the Mass Donors in High-mass X-ray Binaries and Symbiotic Stars

Directory of Open Access Journals (Sweden)

K. Stoyanov

2015-02-01

Full Text Available Our aim is to investigate the tidal interaction in High-mass X-ray Binaries and Symbiotic stars in order to determine in which objects the rotation of the mass donors is synchronized or pseudosynchronized with the orbital motion of the compact companion. We find that the Be/X-ray binaries are not synchronized and the orbital periods of the systems are greater than the rotational periods of the mass donors. The giant and supergiant High-mass X-ray binaries and symbiotic stars are close to synchronization. We compare the rotation of mass donors in symbiotics with the projected rotational velocities of field giants and find that the M giants in S-type symbiotics rotate on average 1.5 times faster than the field M giants. We find that the projected rotational velocity of the red giant in symbiotic star MWC 560 is v sin i= 8.2±1.5 km.s−1, and estimate its rotational period to be Prot<>/sub = 144 - 306 days. Using the theoretical predictions of tidal interaction and pseudosynchronization, we estimate the orbital eccentricity e = 0.68 − 0.82.

Radio emission from the X-ray pulsar Her X-1: a jet launched by a strong magnetic field neutron star?

Science.gov (United States)

van den Eijnden, J.; Degenaar, N.; Russell, T. D.; Miller-Jones, J. C. A.; Wijnands, R.; Miller, J. M.; King, A. L.; Rupen, M. P.

2018-01-01

Her X-1 is an accreting neutron star (NS) in an intermediate-mass X-ray binary. Like low-mass X-ray binaries (LMXBs), it accretes via Roche lobe overflow, but similar to many high-mass X-ray binaries containing a NS; Her X-1 has a strong magnetic field and slow spin. Here, we present the discovery of radio emission from Her X-1 with the Very Large Array. During the radio observation, the central X-ray source was partially obscured by a warped disc. We measure a radio flux density of 38.7 ± 4.8 μJy at 9 GHz but cannot constrain the spectral shape. We discuss possible origins of the radio emission, and conclude that coherent emission, a stellar wind, shocks and a propeller outflow are all unlikely explanations. A jet, as seen in LMXBs, is consistent with the observed radio properties. We consider the implications of the presence of a jet in Her X-1 on jet formation mechanisms and on the launching of jets by NSs with strong magnetic fields.

Detection of Reflection Features in the Neutron Star Low-mass X-Ray Binary Serpens X-1 with NICER

DEFF Research Database (Denmark)

Ludlam, R. M.; Miller, J. M.; Arzoumanian, Z.

2018-01-01

We present Neutron Star Interior Composition Explorer (NICER) observations of the neutron star (NS) low-mass X-ray binary Serpens X-1 during the early mission phase in 2017. With the high spectral sensitivity and low-energy X-ray passband of NICER, we are able to detect the Fe L line complex in a...

Energy Feedback from X-ray Binaries in the Early Universe

Science.gov (United States)

Fragos, T.; Lehmer, B..; Naoz, S.; Zezas, A.; Basu-Zych, A.

2013-01-01

X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z (redshift) approximately equal to 20) until today.We estimate that X-ray emission from XRBs dominates over AGN at z (redshift) greater than or approximately equal to 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by approximately 4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of approximately 300 Myr (million years) and then decreases gradually at later times, showing little variation for mean stellar ages 3 Gyr (Giga years, or billion years). Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations.

The NuSTAR Hard X-Ray Survey of the Norma Arm Region

Energy Technology Data Exchange (ETDEWEB)

Fornasini, Francesca M. [Astronomy Department, University of California, 601 Campbell Hall, Berkeley, CA 94720 (United States); Tomsick, John A.; Chiu, Jeng-Lun; Clavel, Maïca; Krivonos, Roman A.; Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720 (United States); Hong, JaeSub [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gotthelf, Eric V.; Hailey, Charles J.; Mori, Kaya [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Bauer, Franz; Corral-Santana, Jesús [Instituto de Astrofísica and Centro de Astroingeniería, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Rahoui, Farid [European Southern Observatory, K. Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Bodaghee, Arash [Georgia College, 231 W. Hancock Street, Milledgeville, GA 31061 (United States); Alexander, David M. [Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, DH1 3LE (United Kingdom); Barret, Didier [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); CNRS, Institut de Recherche en Astrophysique et Planétologie, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France); Christensen, Finn E., E-mail: f.fornasini@berkeley.edu [DTU Space—National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); and others

2017-04-01

We present a catalog of hard X-ray sources in a square-degree region surveyed by the Nuclear Spectroscopic Telescope Array ( NuSTAR ) in the direction of the Norma spiral arm. This survey has a total exposure time of 1.7 Ms, and the typical and maximum exposure depths are 50 ks and 1 Ms, respectively. In the area of deepest coverage, sensitivity limits of 5 × 10{sup −14} and 4 × 10{sup −14} erg s{sup −1} cm{sup −2} in the 3–10 and 10–20 keV bands, respectively, are reached. Twenty-eight sources are firmly detected, and 10 are detected with low significance; 8 of the 38 sources are expected to be active galactic nuclei. The three brightest sources were previously identified as a low-mass X-ray binary, high-mass X-ray binary, and pulsar wind nebula. Based on their X-ray properties and multiwavelength counterparts, we identify the likely nature of the other sources as two colliding wind binaries, three pulsar wind nebulae, a black hole binary, and a plurality of cataclysmic variables (CVs). The CV candidates in the Norma region have plasma temperatures of ≈10–20 keV, consistent with the Galactic ridge X-ray emission spectrum but lower than the temperatures of CVs near the Galactic center. This temperature difference may indicate that the Norma region has a lower fraction of intermediate polars relative to other types of CVs compared to the Galactic center. The NuSTAR log N –log S distribution in the 10–20 keV band is consistent with the distribution measured by Chandra at 2–10 keV if the average source spectrum is assumed to be a thermal model with kT  ≈ 15 keV, as observed for the CV candidates.

AN X-RAY AND OPTICAL LIGHT CURVE MODEL OF THE ECLIPSING SYMBIOTIC BINARY SMC3

International Nuclear Information System (INIS)

Kato, Mariko; Hachisu, Izumi; Mikołajewska, Joanna

2013-01-01

Some binary evolution scenarios for Type Ia supernovae (SNe Ia) include long-period binaries that evolve to symbiotic supersoft X-ray sources in their late stage of evolution. However, symbiotic stars with steady hydrogen burning on the white dwarf's (WD) surface are very rare, and the X-ray characteristics are not well known. SMC3 is one such rare example and a key object for understanding the evolution of symbiotic stars to SNe Ia. SMC3 is an eclipsing symbiotic binary, consisting of a massive WD and red giant (RG), with an orbital period of 4.5 years in the Small Magellanic Cloud. The long-term V light curve variations are reproduced as orbital variations in the irradiated RG, whose atmosphere fills its Roche lobe, thus supporting the idea that the RG supplies matter to the WD at rates high enough to maintain steady hydrogen burning on the WD. We also present an eclipse model in which an X-ray-emitting region around the WD is almost totally occulted by the RG swelling over the Roche lobe on the trailing side, although it is always partly obscured by a long spiral tail of neutral hydrogen surrounding the binary in the orbital plane.

What Can We Learn About Black-Hole Formation from Black-Hole X-ray Binaries?

NARCIS (Netherlands)

Nelemans, G.A.

2007-01-01

I discuss the effect of the formation of a black hole on a (close) binary and show some of the current constraints that the observed properties of black hole X-ray binaries put on the formation of black holes. In particular, I discuss the evidence for and against asymmetric kicks imparted on the

PROBING WOLF–RAYET WINDS: CHANDRA/HETG X-RAY SPECTRA OF WR 6

Energy Technology Data Exchange (ETDEWEB)

Huenemoerder, David P.; Schulz, N. S. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139 (United States); Gayley, K. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Hamann, W.-R.; Oskinova, L.; Shenar, T. [Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, D-14476 Potsdam (Germany); Ignace, R. [Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37614 (United States); Nichols, J. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS 34, Cambridge, MA 02138 (United States); Pollock, A. M. T., E-mail: dph@space.mit.edu, E-mail: ken.gayley@gmail.com, E-mail: wrh@astro.physik.uni-potsdam.de, E-mail: lida@astro.physik.uni-potsdam.de, E-mail: shtomer@astro.physik.uni-potsdam.de, E-mail: ignace@mail.etsu.edu, E-mail: jnichols@cfa.harvard.edu [European Space Agency, ESAC, Apartado 78, E-28691 Villanueva de la Cañada (Spain)

2015-12-10

With a deep Chandra/HETGS exposure of WR 6, we have resolved emission lines whose profiles show that the X-rays originate from a uniformly expanding spherical wind of high X-ray-continuum optical depth. The presence of strong helium-like forbidden lines places the source of X-ray emission at tens to hundreds of stellar radii from the photosphere. Variability was present in X-rays and simultaneous optical photometry, but neither were correlated with the known period of the system or with each other. An enhanced abundance of sodium revealed nuclear-processed material, a quantity related to the evolutionary state of the star. The characterization of the extent and nature of the hot plasma in WR 6 will help to pave the way to a more fundamental theoretical understanding of the winds and evolution of massive stars.

X-ray emission from hot subdwarfs with compact companions

Directory of Open Access Journals (Sweden)

Esposito P.

2013-03-01

Full Text Available We review the X-ray observations of hot subdwarf stars. While no X-ray emission has been detected yet from binaries containing B-type subdwarfs, interesting results have been obtained in the case of the two luminous O-type subdwarfs HD 49798 and BD + 37° 442. Both of them are members of binary systems in which the X-ray luminosity is powered by accretion onto a compact object: a rapidly spinning (13.2 s and massive (1.28  M⊙ white dwarf in the case of HD 49798 and most likely a neutron star, spinning at 19.2 s, in the case of BD + 37° 442. Their study can shed light on the poorly known processes taking place during common envelope evolutionary phases and on the properties of wind mass loss from hot subdwarfs.

Formation of Black Hole X-Ray Binaries with Non-degenerate Donors in Globular Clusters

Energy Technology Data Exchange (ETDEWEB)

Ivanova, Natalia; Rocha, Cassio A. da; Van, Kenny X.; Nandez, Jose L. A., E-mail: nata.ivanova@ualberta.ca [Department of Physics, University of Alberta, Edmonton, AB T6G 2E7 (Canada)

2017-07-10

In this Letter, we propose a formation channel for low-mass X-ray binaries with black hole accretors and non-degenerate donors via grazing tidal encounters with subgiants. We estimate that in a typically dense globular cluster with a core density of 10{sup 5} stars pc{sup −3}, the formation rates are about one binary per Gyr per 50–100 retained black holes. The donors—stripped subgiants—will be strongly underluminous when compared to subgiant or giant branch stars of the same colors. The products of tidal stripping are underluminous by at least one magnitude for several hundred million years when compared to normal stars of the same color, and differ from underluminous red stars that could be produced by non-catastrophic mass transfer in an ordinary binary. The dynamically formed binaries become quiescent LMXBs, with lifetimes of about a Gyr. The expected number of X-ray binaries is one per 50–200 retained black holes, while the expected number of strongly underluminous subsubgiant is about half this. The presence of strongly underluminous stars in a GC may be indicative of the presence of black holes.

Formation of Black Hole X-Ray Binaries with Non-degenerate Donors in Globular Clusters

International Nuclear Information System (INIS)

Ivanova, Natalia; Rocha, Cassio A. da; Van, Kenny X.; Nandez, Jose L. A.

2017-01-01

In this Letter, we propose a formation channel for low-mass X-ray binaries with black hole accretors and non-degenerate donors via grazing tidal encounters with subgiants. We estimate that in a typically dense globular cluster with a core density of 10 5 stars pc −3 , the formation rates are about one binary per Gyr per 50–100 retained black holes. The donors—stripped subgiants—will be strongly underluminous when compared to subgiant or giant branch stars of the same colors. The products of tidal stripping are underluminous by at least one magnitude for several hundred million years when compared to normal stars of the same color, and differ from underluminous red stars that could be produced by non-catastrophic mass transfer in an ordinary binary. The dynamically formed binaries become quiescent LMXBs, with lifetimes of about a Gyr. The expected number of X-ray binaries is one per 50–200 retained black holes, while the expected number of strongly underluminous subsubgiant is about half this. The presence of strongly underluminous stars in a GC may be indicative of the presence of black holes.

An x-ray nebula associated with the millisecond pulsar B1957+20.

Science.gov (United States)

Stappers, B W; Gaensler, B M; Kaspi, V M; van der Klis, M; Lewin, W H G

2003-02-28

We have detected an x-ray nebula around the binary millisecond pulsar B1957+20. A narrow tail, corresponding to the shocked pulsar wind, is seen interior to the known Halpha bow shock and proves the long-held assumption that the rotational energy of millisecond pulsars is dissipated through relativistic winds. Unresolved x-ray emission likely represents the shock where the winds of the pulsar and its companion collide. This emission indicates that the efficiency with which relativistic particles are accelerated in the postshock flow is similar to that for young pulsars, despite the shock proximity and much weaker surface magnetic field of this millisecond pulsar.

Variable millimetre radiation from the colliding-wind binary Cygnus OB2 #8A

Science.gov (United States)

Blomme, R.; Fenech, D. M.; Prinja, R. K.; Pittard, J. M.; Morford, J. C.

2017-12-01

Context. Massive binaries have stellar winds that collide. In the colliding-wind region, various physically interesting processes occur, leading to enhanced X-ray emission, non-thermal radio emission, as well as non-thermal X-rays and gamma-rays. Non-thermal radio emission (due to synchrotron radiation) has so far been observed at centimetre wavelengths. At millimetre wavelengths, the stellar winds and the colliding-wind region emit more thermal free-free radiation, and it is expected that any non-thermal contribution will be difficult or impossible to detect. Aims: We aim to determine if the material in the colliding-wind region contributes substantially to the observed millimetre fluxes of a colliding-wind binary. We also try to distinguish the synchrotron emission from the free-free emission. Methods: We monitored the massive binary Cyg OB2 #8A at 3 mm with the NOrthern Extended Millimeter Array (NOEMA) interferometer of the Institut de Radioastronomie Millimétrique (IRAM). The data were collected in 14 separate observing runs (in 2014 and 2016), and provide good coverage of the orbital period. Results: The observed millimetre fluxes range between 1.1 and 2.3 mJy, and show phase-locked variability, clearly indicating that a large part of the emission is due to the colliding-wind region. A simple synchrotron model gives fluxes with the correct order of magnitude, but with a maximum that is phase-shifted with respect to the observations. Qualitatively this phase shift can be explained by our neglect of orbital motion on the shape of the colliding-wind region. A model using only free-free emission results in only a slightly worse explanation of the observations. Additionally, on the map of our observations we also detect the O6.5 III star Cyg OB2 #8B, for which we determine a 3 mm flux of 0.21 ± 0.033 mJy. Conclusions: The question of whether synchrotron radiation or free-free emission dominates the millimetre fluxes of Cyg OB2 #8A remains open. More detailed

X-ray diagnostic device with an X-ray image amplifier, whose output image is fed into a movie camera, as well as a brightness control

Energy Technology Data Exchange (ETDEWEB)

Lutz, H

1978-02-09

The X-ray relief appearing behind a patient is immediately or with amplificating foils converted into a latent film image. By using a X-ray image amplifier the X-ray relief is then converted into a reduced and brighter optical image and fed into a photographic or movie camera and shot. To avoid a reduction in the image quality by quantum noise and a too large patient and physician dose a brightness control is provided for the X-ray diagnostic device. The control only dims as far as a brightness per image is produced that avoids quantum noise. On the other side it opens more by strongly beam absorbing patients or a smaller imaging ratio of the X-ray image amplifier to obtain a desired irradiation.

The disc-jet coupling in the neutron star X-ray binary 4U 1728-34

NARCIS (Netherlands)

Tudose, Valeriu; Tzioumis, Anastasios; Belloni, Tomaso; Altamirano, Diego; Linares, Manuel; Mendez, Mariano; Hiemstra, Beike

2010-01-01

The present radio proposal is part of a multi-wavelength campaign focused on the study of the accretion/ejection process in the neutron star X-ray binary system 4U 1728-34. Our intention is to study the behaviour of the inner part of the accretion disc as inferred from the X-ray observations of the

Si K EDGE STRUCTURE AND VARIABILITY IN GALACTIC X-RAY BINARIES

Energy Technology Data Exchange (ETDEWEB)

Schulz, Norbert S.; Corrales, Lia; Canizares, Claude R. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2016-08-10

We survey the Si K edge structure in various absorbed Galactic low-mass X-ray binaries (LMXBs) to study states of silicon in the inter- and circum-stellar medium. The bulk of these LMXBs lie toward the Galactic bulge region and all have column densities above 10{sup 22} cm{sup −2}. The observations were performed using the Chandra High Energy Transmission Grating Spectrometer. The Si K edge in all sources appears at an energy value of 1844 ± 0.001 eV. The edge exhibits significant substructure that can be described by a near edge absorption feature at 1849 ± 0.002 eV and a far edge absorption feature at 1865 ± 0.002 eV. Both of these absorption features appear variable with equivalent widths up to several mÅ. We can describe the edge structure using several components: multiple edge functions, near edge absorption excesses from silicates in dust form, signatures from X-ray scattering optical depths, and a variable warm absorber from ionized atomic silicon. The measured optical depths of the edges indicate much higher values than expected from atomic silicon cross sections and interstellar medium abundances, and they appear consistent with predictions from silicate X-ray absorption and scattering. A comparison with models also indicates a preference for larger dust grain sizes. In many cases, we identify Si xiii resonance absorption and determine ionization parameters between log ξ = 1.8 and 2.8 and turbulent velocities between 300 and 1000 km s{sup −1}. This places the warm absorber in close vicinity of the X-ray binaries. In some data, we observe a weak edge at 1.840 keV, potentially from a lesser contribution of neutral atomic silicon.

MAGNETOHYDRODYNAMIC ACCRETION DISK WINDS AS X-RAY ABSORBERS IN ACTIVE GALACTIC NUCLEI

International Nuclear Information System (INIS)

Fukumura, Keigo; Kazanas, Demosthenes; Behar, Ehud; Contopoulos, Ioannis

2010-01-01

We present the two-dimensional ionization structure of self-similar magnetohydrodynamic winds off accretion disks around and irradiated by a central X-ray point source. On the basis of earlier observational clues and theoretical arguments, we focus our attention on a subset of these winds, namely those with radial density dependence n(r) ∝ 1/r (r is the spherical radial coordinate). We employ the photoionization code XSTAR to compute the ionic abundances of a large number of ions of different elements and then compile their line-of-sight (LOS) absorption columns. We focus our attention on the distribution of the column density of the various ions as a function of the ionization parameter ξ (or equivalently r) and the angle θ. Particular attention is paid to the absorption measure distribution (AMD), namely their hydrogen-equivalent column per logarithmic ξ interval, dN H /dlog ξ, which provides a measure of the winds' radial density profiles. For the chosen density profile n(r) ∝ 1/r, the AMD is found to be independent of ξ, in good agreement with its behavior inferred from the X-ray spectra of several active galactic nuclei (AGNs). For the specific wind structure and X-ray spectrum, we also compute detailed absorption line profiles for a number of ions to obtain their LOS velocities, v ∼ 100-300 km s -1 (at log ξ ∼ 2-3) for Fe XVII and v ∼ 1000-4000 km s -1 (at log ξ ∼ 4-5) for Fe XXV, in good agreement with the observation. Our models describe the X-ray absorption properties of these winds with only two parameters, namely the mass-accretion rate m-dot and the LOS angle θ. The probability of obscuration of the X-ray ionizing source in these winds decreases with increasing m-dot and increases steeply with the LOS inclination angle θ. As such, we concur with previous authors that these wind configurations, viewed globally, incorporate all the requisite properties of the parsec scale 'torii' invoked in AGN unification schemes. We indicate that a

X-ray emission and the winds of cataclysmic variables

International Nuclear Information System (INIS)

Cordova, F.A.

1985-01-01

X-ray and ultraviolet observations of cataclysmic variable stars reveal a variety of exotic behavior - pulsations, winds, and episodic outbursts - are these related, what do they tell us about the nature of the outburst, about the environment of the accreting white dwarf. The author summarizes the observed changes in the x-ray and uv continuum and spectral features through the outbursts of the dwarf novae. The author then discusses how the modeling of these data have refined our ideas about the location and nature of the emissions, and the source of the outbursts. The author shows how comparisons of the x-ray and uv properties of cataclysmic variables with similar phenomena in other astronomical systems - the solar corona, OB stars, and Be stars - suggest ways in which the x-ray and uv emissions in CVs may be related, and point to further, specific observations that would elucidate our understanding of the behavior and role of the white dwarf in the outburst. 26 references

Modeling X-ray Absorbers in AGNs with MHD-Driven Accretion-Disk Winds

Science.gov (United States)

Fukumura, Keigo; Kazanas, D.; Shrader, C. R.; Tombesi, F.; Contopoulos, J.; Behar, E.

2013-04-01

We have proposed a systematic view of the observed X-ray absorbers, namely warm absorbers (WAs) in soft X-ray and highly-ionized ultra-fast outflows (UFOs), in the context of magnetically-driven accretion-disk wind models. While potentially complicated by variability and thermal instability in these energetic outflows, in this simplistic model we have calculated 2D kinematic field as well as density and ionization structure of the wind with density profile of 1/r corresponding to a constant column distribution per decade of ionization parameter. In particular we show semi-analytically that the inner layer of the disk-wind manifests itself as the strongly-ionized fast outflows while the outer layer is identified as the moderately-ionized absorbers. The computed characteristics of these two apparently distinct absorbers are consistent with X-ray data (i.e. a factor of ~100 difference in column and ionization parameters as well as low wind velocity vs. near-relativistic flow). With the predicted contour curves for these wind parameters one can constrain allowed regions for the presence of WAs and UFOs.The model further implies that the UFO's gas pressure is comparable to that of the observed radio jet in 3C111 suggesting that the magnetized disk-wind with density profile of 1/r is a viable agent to help sustain such a self-collimated jet at small radii.

X-ray diagnostic device with an X-ray image amplifier, whose output image is fed into a movie camera, as well as a brightness control

International Nuclear Information System (INIS)

Lutz, H.

1978-01-01

The X-ray relief appearing behind a patient is immediately or with amplificating foils converted into a latent film image. By using a X-ray image amplifier the X-ray relief is then converted into a reduced and brighter optical image and fed into a photographic or movie camera and shot. To avoid a reduction in the image quality by quantum noise and a too large patient and physician dose a brightness control is provided for the X-ray diagnostic device. The control only dims as far as a brightness per image is produced that avoids quantum noise. On the other side it opens more by strongly beam absorbing patients or a smaller imaging ratio of the X-ray image amplifier to obtain a desired irradiation. (DG) [de

Line features in the X-ray spectrum of the crab pulsar

International Nuclear Information System (INIS)

Hasinger, G.; Pietsch, W.; Reppin, C.; Truemper, J.; Voges, W.; Kendziorra, E.; Staubert, R.

1982-01-01

Beside the well-known synchrotron behaviour of the Crab pulsar, there may be another source of high energy emission due to a hot plasma. The similarities between this component and common accretion-fed X-ray binaries are the frame in which the present balloon observation of the Crab pulsar will be discussed. (orig./WL)

Wide Field-of-View Soft X-Ray Imaging for Solar Wind-Magnetosphere Interactions

Science.gov (United States)

Walsh, B. M.; Collier, M. R.; Kuntz, K. D.; Porter, F. S.; Sibeck, D. G.; Snowden, S. L.; Carter, J. A.; Collado-Vega, Y.; Connor, H. K.; Cravens, T. E.;

On the Symbiotic X-Ray Binary Nature of the Star CGCS 5926

Directory of Open Access Journals (Sweden)

Masetti N.

2012-06-01

Full Text Available We report on multiwavelength (from X-ray to optical follow up observations of a carbon star CGCS 5926, motivated by the fact that it is positionally coincident with a faint X-ray source of the ROSAT catalog, thus suggesting its possible symbiotic X-ray binary (SyXB nature. Our optical spectroscopy confirms that this is a carbon star of type C(6,2. This allows us to infer for CGCS 5926 a distance of ~5 kpc. BVRCIC photometry of the star shows variability of ~0.3 mag with a periodicity of 151 days, which we interpret as due to radial pulsations. the source is not detected with the Swift satellite in X-rays down to a 0.3-10 keV luminosity of ~3 × 1032 erg s−1. This nondetection is apparently in contrast with the ROSAT data; however, the present information does not rule out that CGCS 5926 can be a SyXB. This will be settled by more sensitive observations at high energies.

Contrasting Behaviour from Two Be/X-ray Binary Pulsars: Insights into Differing Neutron Star Accretion Modes

Science.gov (United States)

Townsend, L. J.; Drave, S. P.; Hill, A. B.; Coe, M. J.; Corbet, R. H. D.; Bird, A. J.

2013-01-01

In this paper we present the identification of two periodic X-ray signals coming from the direction of the Small Magellanic Cloud (SMC). On detection with the Rossi X-ray Timing Explorer (RXTE), the 175.4 s and 85.4 s pulsations were considered to originate from new Be/X-ray binary (BeXRB) pulsars with unknown locations. Using rapid follow-up INTEGRAL and XMM-Newton observations, we show the first pulsar (designated SXP175) to be coincident with a candidate high-mass X-ray binary (HMXB) in the northern bar region of the SMC undergoing a small Type II outburst. The orbital period (87d) and spectral class (B0-B0.5IIIe) of this system are determined and presented here for the first time. The second pulsar is shown not to be new at all, but is consistent with being SXP91.1 - a pulsar discovered at the very beginning of the 13 year long RXTE key monitoring programme of the SMC. Whilst it is theoretically possible for accreting neutron stars to change spin period so dramatically over such a short time, the X-ray and optical data available for this source suggest this spin-up is continuous during long phases of X-ray quiescence, where accretion driven spin-up of the neutron star should be minimal.

Timing and Spectral Studies of the Peculiar X-ray Binary Circinus X-1

Energy Technology Data Exchange (ETDEWEB)

Saz Parkinson, Pablo M.

2003-08-26

Circinus X-1 (Cir X-1) is an X-ray binary displaying an array of phenomena which makes it unique in our Galaxy. Despite several decades of observation, controversy surrounds even the most basic facts about this system. It is generally classified as a Neutron Star (NS) Low Mass X-ray Binary (LMXB),though this classification is based primarily on the observation of Type I X-ray Bursts by EXOSAT in 1985. It is believed to be in a very eccentric {approx} 16.5 day orbit, displaying periodic outbursts in the radio and other frequency bands (including optical and IR) which reinforce the notion that this is in fact the orbital period. Cir X-1 lies in the plane of the Galaxy, where optical identification of the companion is made difficult due to dust obscuration. The companion is thought to be a low mass star, though a high mass companion has not currently been ruled out. In this work, the author analyzes recent observations of Cir X-1 made with the Unconventional Stellar Aspect (USA) experiment, as well as archival observations of Cir X-1 made by a variety of instruments, from as early as 1969. The fast (< 1 s) timing properties of Cir X-1 are studied by performing FFT analyses of the USA data. Quasi-Periodic Oscillations (QPOs) in the 1-50 Hz range are found and discussed in the context of recent correlations which question the leading models invoked for their generation. The energy dependence of the QPOs (rms increasing with energy) argues against them being generated in the disk and favors models in which the QPOs are related to a higher energy Comptonizing component. The power spectrum of Cir X-1 in its soft state is compared to that of Cygnus X-1 (Cyg X-1), the prototypical black hole candidate. Using scaling arguments the author argues that the mass of Cir X-1 could exceed significantly the canonical 1.4 M{circle_dot} mass of a neutron star, possibly partly explaining why this object appears so different to other neutron stars. The spectral evolution of Cir X-1 is

On the rarity of X-ray binaries with Wolf-Rayet donors

Energy Technology Data Exchange (ETDEWEB)

Linden, T. [Univ. of California, Santa Cruz, CA (United States); Fermi National Accelerator Lab., Batavia, IL (United States); Valsecchi, F. [Northwestern Univ., Evanston, IL (United States); Kalogera, V. [Northwestern Univ., Evanston, IL (United States)

2012-03-14

The paucity of High mass X-Ray binaries (HMXB) consisting of a neutron star (NS) accretor and Wolf-Rayet (WR) donor has long been at odds with expectations from population synthesis studies indicating that these systems should survive as the evolved offspring of the observed HMXB population. This tension is particularly troubling in light of recent observations uncovering a preponderance of HMXBs containing loosely bound Be donors which would be expected to naturally evolve into WR-HMXBs. Reconciling the unexpectedly large population of Be-HMXBs with the lack of observed WR-HMXB sources thus serves to isolate the dynamics of CE physics from other binary evolution parameters. We find that binary mergers during CE events must be common in order to resolve tension between these observed populations. Furthermore, future observations which better constrain the background population of loosely bound O/B-NS binaries are likely to place significant constraints on the efficiency of CE removal.

IGR J19294+1816: a new Be-X-ray binary revealed through infrared spectroscopy

Science.gov (United States)

Rodes-Roca, J. J.; Bernabeu, G.; Magazzù, A.; Torrejón, J. M.; Solano, E.

2018-05-01

The aim of this work is to characterize the counterpart to the INTErnational Gamma-Ray Astrophysics Laboratory high-mass X-ray binary candidate IGR J19294+1816 so as to establish its true nature. We obtained H-band spectra of the selected counterpart acquired with the Near Infrared Camera and Spectrograph instrument mounted on the Telescopio Nazionale Galileo 3.5-m telescope which represents the first infrared spectrum ever taken of this source. We complement the spectral analysis with infrared photometry from UKIDSS, 2MASS, WISE, and NEOWISE data bases. We classify the mass donor as a Be star. Subsequently, we compute its distance by properly taking into account the contamination produced by the circumstellar envelope. The findings indicate that IGR J19294+1816 is a transient source with a B1Ve donor at a distance of d = 11 ± 1 kpc, and luminosities of the order of 1036-37 erg s-1, displaying the typical behaviour of a Be-X-ray binary.

The Giant Flares of the Microquasar Cygnus X-3: X-Rays States and Jets

Directory of Open Access Journals (Sweden)

Sergei Trushkin

2017-11-01

Full Text Available We report on two giant radio flares of the X-ray binary microquasar Cyg X-3, consisting of a Wolf–Rayet star and probably a black hole. The first flare occurred on 13 September 2016, 2000 days after a previous giant flare in February 2011, as the RATAN-600 radio telescope daily monitoring showed. After 200 days on 1 April 2017, we detected a second giant flare. Both flares are characterized by the increase of the fluxes by almost 2000-times (from 5–10 to 17,000 mJy at 4–11 GHz during 2–7 days, indicating relativistic bulk motions from the central region of the accretion disk around a black hole. The flaring light curves and spectral evolution of the synchrotron radiation indicate the formation of two relativistic collimated jets from the binaries. Both flares occurred when the source went from hypersoft X-ray states to soft ones, i.e. hard fluxes (Swift/BAT 15–50 keV data dropped to zero, the soft X-ray fluxes (MAXI 2–10 keV data staying high, and then later, the binary came back to a hard state. Both similar giant flares indicated the unchanged mechanism of the jets’ formation in Cyg X-3, probably in conditions of strong stellar wind and powerful accretion onto a black hole.

X-ray states of redback millisecond pulsars

Energy Technology Data Exchange (ETDEWEB)

Linares, M. [Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain)

2014-11-01

Compact binary millisecond pulsars with main-sequence donors, often referred to as 'redbacks', constitute the long-sought link between low-mass X-ray binaries and millisecond radio pulsars and offer a unique probe of the interaction between pulsar winds and accretion flows. We present a systematic study of eight nearby redbacks, using more than 100 observations obtained with Swift's X-ray Telescope. We distinguish between three main states: pulsar, disk, and outburst states. We find X-ray mode switching in the disk state of PSR J1023+0038 and XSS J12270-4859, similar to what was found in the other redback that showed evidence for accretion: rapid, recurrent changes in X-ray luminosity (0.5-10 keV, L {sub X}), between (6-9) × 10{sup 32} erg s{sup –1} (disk-passive state) and (3-5) × 10{sup 33} erg s{sup –1} (disk-active state). This strongly suggests that mode switching—which has not been observed in quiescent low-mass X-ray binaries—is universal among redback millisecond pulsars in the disk state. We briefly explore the implications for accretion disk truncation and find that the inferred magnetospheric radius in the disk state of PSR J1023+0038 and XSS J12270-4859 lies outside the light cylinder. Finally, we note that all three redbacks that have developed accretion disks have relatively high L {sub X} in the pulsar state (>10{sup 32} erg s{sup –1}).

WATCHDOG: A COMPREHENSIVE ALL-SKY DATABASE OF GALACTIC BLACK HOLE X-RAY BINARIES

International Nuclear Information System (INIS)

Tetarenko, B. E.; Sivakoff, G. R.; Heinke, C. O.; Gladstone, J. C.

2016-01-01

With the advent of more sensitive all-sky instruments, the transient universe is being probed in greater depth than ever before. Taking advantage of available resources, we have established a comprehensive database of black hole (and black hole candidate) X-ray binary (BHXB) activity between 1996 and 2015 as revealed by all-sky instruments, scanning surveys, and select narrow-field X-ray instruments on board the INTErnational Gamma-Ray Astrophysics Laboratory, Monitor of All-Sky X-ray Image, Rossi X-ray Timing Explorer, and Swift telescopes; the Whole-sky Alberta Time-resolved Comprehensive black-Hole Database Of the Galaxy or WATCHDOG. Over the past two decades, we have detected 132 transient outbursts, tracked and classified behavior occurring in 47 transient and 10 persistently accreting BHs, and performed a statistical study on a number of outburst properties across the Galactic population. We find that outbursts undergone by BHXBs that do not reach the thermally dominant accretion state make up a substantial fraction (∼40%) of the Galactic transient BHXB outburst sample over the past ∼20 years. Our findings suggest that this “hard-only” behavior, observed in transient and persistently accreting BHXBs, is neither a rare nor recent phenomenon and may be indicative of an underlying physical process, relatively common among binary BHs, involving the mass-transfer rate onto the BH remaining at a low level rather than increasing as the outburst evolves. We discuss how the larger number of these “hard-only” outbursts and detected outbursts in general have significant implications for both the luminosity function and mass-transfer history of the Galactic BHXB population

Two methods for studying the X-ray variability

NARCIS (Netherlands)

Yan, Shu-Ping; Ji, Li; Méndez, Mariano; Wang, Na; Liu, Siming; Li, Xiang-Dong

2016-01-01

The X-ray aperiodic variability and quasi-periodic oscillation (QPO) are the important tools to study the structure of the accretion flow of X-ray binaries. However, the origin of the complex X-ray variability from X-ray binaries remains yet unsolved. We proposed two methods for studying the X-ray

X-ray sky

International Nuclear Information System (INIS)

Gruen, M.; Koubsky, P.

1977-01-01

The history is described of the discoveries of X-ray sources in the sky. The individual X-ray detectors are described in more detail, i.e., gas counters, scintillation detectors, semiconductor detectors, and the principles of X-ray spectrometry and of radiation collimation aimed at increased resolution are discussed. Currently, over 200 celestial X-ray sources are known. Some were identified as nebulae, in some pulsations were found or the source was identified as a binary star. X-ray bursts of novae were also observed. The X-ray radiation is briefly mentioned of spherical star clusters and of extragalactic X-ray sources. (Oy)

Ultraviolet, X-ray, and infrared observations of HDE 226868 equals Cygnus X-1

Science.gov (United States)

Treves, A.; Chiappetti, L.; Tanzi, E. G.; Tarenghi, M.; Gursky, H.; Dupree, A. K.; Hartmann, L. W.; Raymond, J.; Davis, R. J.; Black, J.

1980-01-01

During April, May, and July of 1978, HDE 226868, the optical counterpart of Cygnus X-1, was repeatedly observed in the ultraviolet with the IUE satellite. Some X-ray and infrared observations have been made during the same period. The general shape of the spectrum is that expected from a late O supergiant. Strong absorption features are apparent in the ultraviolet, some of which have been identified. The equivalent widths of the most prominent lines appear to be modulated with the orbital phase. This modulation is discussed in terms of the ionization contours calculated by Hatchett and McCray, for a binary X-ray source in the stellar wind of the companion.

BROADBAND X-RAY PROPERTIES OF THE GAMMA-RAY BINARY 1FGL J1018.6–5856

International Nuclear Information System (INIS)

An, Hongjun; Bellm, Eric; Fuerst, Felix; Harrison, Fiona A.; Bhalerao, Varun; Boggs, Steven E.; Craig, William W.; Tomsick, John A.; Christensen, Finn E.; Hailey, Charles J.; Kaspi, Victoria M.; Natalucci, Lorenzo; Stern, Daniel; Zhang, William W.

2015-01-01

We report on NuSTAR, XMM-Newton, and Swift observations of the gamma-ray binary 1FGL J1018.6–5856. We measure the orbital period to be 16.544 ± 0.008 days using Swift data spanning 1900 days. The orbital period is different from the 2011 gamma-ray measurement which was used in the previous X-ray study of An et al. using ∼400 days of Swift data, but is consistent with a new gamma-ray solution reported in 2014. The light curve folded on the new period is qualitatively similar to that reported previously, having a spike at phase 0 and broad sinusoidal modulation. The X-ray flux enhancement at phase 0 occurs more regularly in time than was previously suggested. A spiky structure at this phase seems to be a persistent feature, although there is some variability. Furthermore, we find that the source flux clearly correlates with the spectral hardness throughout all orbital phases, and that the broadband X-ray spectra measured with NuSTAR, XMM-Newton, and Swift are well fit with an unbroken power-law model. This spectrum suggests that the system may not be accretion-powered

Hitomi X-ray Observation of the Pulsar Wind Nebula G21.5$-$0.9

OpenAIRE

Hitomi Collaboration; Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; Allen, Steven W.; Angelini, Lorella; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W.; Blandford, Roger; Brenneman, Laura W.; Brown, Gregory V.; Bulbul, Esra

2018-01-01

We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5$-$0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8-80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager (SXI) and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the...

Low-mass X-ray binaries from black hole retaining globular clusters

Science.gov (United States)

Giesler, Matthew; Clausen, Drew; Ott, Christian D.

2018-06-01

Recent studies suggest that globular clusters (GCs) may retain a substantial population of stellar-mass black holes (BHs), in contrast to the long-held belief of a few to zero BHs. We model the population of BH low-mass X-ray binaries (BH-LMXBs), an ideal observable proxy for elusive single BHs, produced from a representative group of Milky Way GCs with variable BH populations. We simulate the formation of BH binaries in GCs through exchange interactions between binary and single stars in the company of tens to hundreds of BHs. Additionally, we consider the impact of the BH population on the rate of compact binaries undergoing gravitational wave driven mergers. The characteristics of the BH-LMXB population and binary properties are sensitive to the GCs structural parameters as well as its unobservable BH population. We find that GCs retaining ˜1000 BHs produce a galactic population of ˜150 ejected BH-LMXBs, whereas GCs retaining only ˜20 BHs produce zero ejected BH-LMXBs. Moreover, we explore the possibility that some of the presently known BH-LMXBs might have originated in GCs and identify five candidate systems.

Low-mass X-ray binaries from black-hole retaining globular clusters

Science.gov (United States)

Giesler, Matthew; Clausen, Drew; Ott, Christian D.

2018-03-01

Recent studies suggest that globular clusters (GCs) may retain a substantial population of stellar-mass black holes (BHs), in contrast to the long-held belief of a few to zero BHs. We model the population of BH low-mass X-ray binaries (BH-LMXBs), an ideal observable proxy for elusive single BHs, produced from a representative group of Milky Way GCs with variable BH populations. We simulate the formation of BH-binaries in GCs through exchange interactions between binary and single stars in the company of tens to hundreds of BHs. Additionally, we consider the impact of the BH population on the rate of compact binaries undergoing gravitational wave driven mergers. The characteristics of the BH-LMXB population and binary properties are sensitive to the GCs structural parameters as well as its unobservable BH population. We find that GCs retaining ˜1000 BHs produce a galactic population of ˜150 ejected BH-LMXBs whereas GCs retaining only ˜20 BHs produce zero ejected BH-LMXBs. Moreover, we explore the possibility that some of the presently known BH-LMXBs might have originated in GCs and identify five candidate systems.

Revelations of X-ray spectral analysis of the enigmatic black hole binary GRS 1915+105

Science.gov (United States)

Peris, Charith; Remillard, Ronald A.; Steiner, James; Vrtilek, Saeqa Dil; Varniere, Peggy; Rodriguez, Jerome; Pooley, Guy

2016-01-01

Of the black hole binaries discovered thus far, GRS 1915+105 stands out as an exceptional source primarily due to its wild X-ray variability, the diversity of which has not been replicated in any other stellar-mass black hole. Although extreme variability is commonplace in its light-curve, about half of the observations of GRS1915+105 show fairly steady X-ray intensity. We report on the X-ray spectral behavior within these steady observations. Our work is based on a vast RXTE/PCA data set obtained on GRS 1915+105 during the course of its entire mission and 10 years of radio data from the Ryle Telescope, which overlap the X-ray data. We find that the steady observations within the X-ray data set naturally separate into two regions in a color-color diagram, which we refer to as steady-soft and steady-hard. GRS 1915+105 displays significant curvature in the Comptonization component within the PCA band pass suggesting significantly heating from a hot disk present in all states. A new Comptonization model 'simplcut' was developed in order to model this curvature to best effect. A majority of the steady-soft observations display a roughly constant inner radius; remarkably reminiscent of canonical soft state black hole binaries. In contrast, the steady-hard observations display a growing disk truncation that is correlated to the mass accretion rate through the disk, which suggests a magnetically truncated disk. A comparison of X-ray model parameters to the canonical state definitions show that almost all steady-soft observations match the criteria of either thermal or steep power law state, while the thermal state observations dominate the constant radius branch. A large portion (80%) of the steady-hard observations matches the hard state criteria when the disk fraction constraint is neglected. These results suggest that within the complexity of this source is a simpler underlying basis of states, which map to those observed in canonical black hole binaries. When

The 4U 0115+63: Another energetic gamma ray binary pulsar

Science.gov (United States)

Chadwick, P. M.; Dipper, N. A.; Dowthwaite, J. C.; Kirkman, I. W.; Mccomb, T. J. L.; Orford, K. J.; Turver, K. E.

1985-01-01

Following the discovery of Her X-1 as a source of pulsed 1000 Gev X-rays, a search for emission from an X-ray binary containing a pulsar with similar values of period, period derivative and luminosity was successful. The sporadic X-ray binary 4U 0115-63 has been observed, with probability 2.5 x 10 to the minus 6 power ergs/s to emit 1000 GeV gamma-rays with a time averaged energy flux of 6 to 10 to the 35th power.

IGR J17544-2619 IN DEPTH WITH SUZAKU: DIRECT EVIDENCE FOR CLUMPY WINDS IN A SUPERGIANT FAST X-RAY TRANSIENT

International Nuclear Information System (INIS)

Rampy, Rachel A.; Smith, David M.; Negueruela, Ignacio

2009-01-01

We present direct evidence for dense clumps of matter in the companion wind in a Supergiant Fast X-ray Transient (SFXT) binary. This is seen as a brief period of enhanced absorption during one of the bright, fast flares that distinguish these systems. The object under study was IGR J17544-2619, and a total of 236 ks of data were accumulated with the Japanese satellite Suzaku. The activity in this period spans a dynamic range of almost 10 4 in luminosity and gives a detailed look at SFXT behavior.

Evolution of tidal capture X-ray binaries - 4U 2127+12 (M15) to 4U 1820-30 (NGC 6624)

International Nuclear Information System (INIS)

Bailyn, C.D.; Grindlay, J.E.

1987-01-01

A new evolutionary scenario for X-ray binaries in globular clusters, which begins with a tidal capture of a main-sequence star by a neutron star and ends with a white dwarf-neutron star system, is presented. For tidal captures of main-sequence stars into orbits too wide to begin mass transfer immediately, the subsequent evolution of the secondary can lead to a common envelope binary similar to what the 9 hr X-ray binary 4U 2127+12 in M15 is suspected to be. If the common envelope is thick enough, it may cause the neutron star and the white dwarf core of the secondary to spiral in, producing a detached white dwarf-neutron star system. Subsequently, gravitational radiation losses may evolve this into the configuration seen in the 11 minute X-ray binary 4U 1820-30 in NGC 6624. This model appears more likely on statistical grounds than formation by collision of a neutron star and a red giant. In some circumstances, the latter process may result in unstable mass transfer, which would result in coalescence rather than a binary system like 4U 1820-30. 34 references

Light curve and pulse profile of the x-ray pulsar Vela X-1

International Nuclear Information System (INIS)

Nagase, Fumiaki; Hayakawa, Satio; Makino, Fumiyoshi; Sato, Naohisa; Makishima, Kazuo.

1983-01-01

The following properties of the X-ray binary pulsar Vela X-1 are presented by reference to its observations in March 1980. The light curve shows a high state and a low state in the first and second halves of an orbital period, respectively, but they may rather be defined as a soft state and hard state, respectively, since the intensity above 9 keV does not appreciably change between these two states. The energy spectra in these states indicate the presence of circumstellar absorption. The pulse profiles at high (9-22 keV) and low (1-9 keV) energies are different, indicating the absorption by cold matter which is probably in the accretion column. The absorber which is responsible for the soft and hard states is attributed to the stellar wind whose flow pattern is consistent with that obtained from optical absorption spectra. The orbital period is obtained by a combined analysis of X-ray data since 1972. No appreciable change of the period gives a constraint on the dynamical behavior of the binary system. (author)

Attempt to explain black hole spin in X-ray binaries by new physics

International Nuclear Information System (INIS)

Bambi, Cosimo

2015-01-01

It is widely believed that the spin of black holes in X-ray binaries is mainly natal. A significant spin-up from accretion is not possible. If the secondary has a low mass, the black hole spin cannot change too much even if the black hole swallows the whole stellar companion. If the secondary has a high mass, its lifetime is too short to transfer the necessary amount of matter and spin the black hole up. However, while black holes formed from the collapse of a massive star with solarmetallicity are expected to have low birth spin, current spin measurements show that some black holes in X-ray binaries are rotating very rapidly. Here we show that, if these objects are not the Kerr black holes of general relativity, the accretion of a small amount of matter (∝2 M s un) can make them look like very fast-rotating Kerr black holes. Such a possibility is not in contradiction with any observation and it can explain current spin measurements in a very simple way. (orig.)

Constraining the inclination of the Low-Mass X-ray Binary Cen X-4

Science.gov (United States)

Hammerstein, Erica K.; Cackett, Edward M.; Reynolds, Mark T.; Miller, Jon M.

2018-05-01

We present the results of ellipsoidal light curve modeling of the low mass X-ray binary Cen X-4 in order to constrain the inclination of the system and mass of the neutron star. Near-IR photometric monitoring was performed in May 2008 over a period of three nights at Magellan using PANIC. We obtain J, H and K lightcurves of Cen X-4 using differential photometry. An ellipsoidal modeling code was used to fit the phase folded light curves. The lightcurve fit which makes the least assumptions about the properties of the binary system yields an inclination of 34.9^{+4.9}_{-3.6} degrees (1σ), which is consistent with previous determinations of the system's inclination but with improved statistical uncertainties. When combined with the mass function and mass ratio, this inclination yields a neutron star mass of 1.51^{+0.40}_{-0.55} M⊙. This model allows accretion disk parameters to be free in the fitting process. Fits that do not allow for an accretion disk component in the near-IR flux gives a systematically lower inclination between approximately 33 and 34 degrees, leading to a higher mass neutron star between approximately 1.7 M⊙ and 1.8 M⊙. We discuss the implications of other assumptions made during the modeling process as well as numerous free parameters and their effects on the resulting inclination.

The 2017 Periastron Passage of PSR B1259-63 in Gamma-rays and X-rays

Science.gov (United States)

Wood, Kent S.; Johnson, Tyrel; Ray, Paul S.; Kerr, Matthew T.; Chernyakova, Masha; Fermi LAT Collaboration

2018-01-01

PSR B1259‑ 63 is a 48-ms radio pulsar in a highly eccentric 3.4-yr orbit with a Be star LS 2883. While the pulsed emission has been detected only in radio, un-pulsed radio, X-ray and gamma-ray emission are regularly observed from the binary system around the periastron. It is likely that the collision of the pulsar wind with the anisotropic wind of the Be star plays a crucial role in the generation of the observed non-thermal emission. The spectral energy distribution observed near periastron peaks in GeV gamma-rays, reaching maximum flux several weeks past periastron. In September 2017 it is being observed for a third periastron passage by the Fermi satellite. Here we present first results of the 2017 multi-wavelength campaign. The 2017 observations are compared to the two previous cycles, and used to test current models. Until recently there was no similar source known in the Galaxy but now a near-twin to it, PSR J2032+4127 , (Pspin=143 ms, Porbit ~50 yr, detectable radio to gamma rays) has been found, and is also undergoing periastron passage in Nov 2017. Gamma-ray and X-ray phenomena in the two sources are compared and discussed. These objects may represent a transitional phase, with possible later phases being accreting pulsars, and eventually perhaps NS-BH or NS-NS binary systems. Portions of this research performed at the US Naval Research Laboratory are sponsored by NASA DPR S-15633-Y.

DEM L241, A SUPERNOVA REMNANT CONTAINING A HIGH-MASS X-RAY BINARY

International Nuclear Information System (INIS)

Seward, F. D.; Charles, P. A.; Foster, D. L.; Dickel, J. R.; Romero, P. S.; Edwards, Z. I.; Perry, M.; Williams, R. M.

2012-01-01

A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a high-mass X-ray binary with an orbital period likely to be of the order of tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass >25 M ☉

DEM L241, A SUPERNOVA REMNANT CONTAINING A HIGH-MASS X-RAY BINARY

Energy Technology Data Exchange (ETDEWEB)

Seward, F. D. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Charles, P. A. [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Foster, D. L. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town (South Africa); Dickel, J. R.; Romero, P. S. [Department of Physics and Astronomy, University of New Mexico, 1919 Lomas Boulevard NE, Albuquerque, NM 87131 (United States); Edwards, Z. I.; Perry, M.; Williams, R. M. [Department of Earth and Space Sciences, Columbus State University, Coca Cola Space Science Center, 701 Front Avenue, Columbus, GA 31901 (United States)

2012-11-10

A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a high-mass X-ray binary with an orbital period likely to be of the order of tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass >25 M {sub Sun}.

The donor star of the X-ray pulsar X1908+075

Science.gov (United States)

Martínez-Núñez, S.; Sander, A.; Gímenez-García, A.; Gónzalez-Galán, A.; Torrejón, J. M.; Gónzalez-Fernández, C.; Hamann, W.-R.

2015-06-01

High-mass X-ray binaries consist of a massive donor star and a compact object. While several of those systems have been well studied in X-rays, little is known for most of the donor stars as they are often heavily obscured in the optical and ultraviolet regime. There is an opportunity to observe them at infrared wavelengths, however. The goal of this study is to obtain the stellar and wind parameters of the donor star in the X1908+075 high-mass X-ray binary system with a stellar atmosphere model to check whether previous studies from X-ray observations and spectral morphology lead to a sufficient description of the donor star. We obtained H- and K-band spectra of X1908+075 and analysed them with the Potsdam Wolf-Rayet (PoWR) model atmosphere code. For the first time, we calculated a stellar atmosphere model for the donor star, whose main parameters are: Mspec = 15 ± 6 M⊙, T∗ = 23-3+6 kK, log geff = 3.0 ± 0.2 and log L/L⊙ = 4.81 ± 0.25. The obtained parameters point towards an early B-type (B0-B3) star, probably in a supergiant phase. Moreover we determined a more accurate distance to the system of 4.85 ± 0.50 kpc than the previously reported value. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.Appendix A is available in electronic form at http://www.aanda.org

Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

Science.gov (United States)

Cantrell, Andrew Glenn

We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves

The disc-jet coupling in the neutron star X-ray binary 4U 1728-34

Science.gov (United States)

Tudose, Valeriu; Tzioumis, Anastasios; Belloni, Tomaso; Altamirano, Diego; Linares, Manuel; Mendez, Mariano; Hiemstra, Beike

2010-10-01

The present radio proposal is part of a multi-wavelength campaign focused on the study of the accretion/ejection process in the neutron star X-ray binary system 4U 1728-34. Our intention is to study the behaviour of the inner part of the accretion disc as inferred from the X-ray observations of the Fe emission line and the kHz quasi-periodic oscillations, and to link it to the properties of the radio jet. To achieve this goal we request 5 × 11h of observing time with ATCA, scheduled at regular intervals in the period 2010 August 27- October 13, the visibility window of the granted X-ray observations with RXTE (PI: Mendez) and Suzaku (PI: Linares).

Formation, evolution and environment of high-mass X-ray binaries

International Nuclear Information System (INIS)

Coleiro, Alexis

2013-01-01

High-Mass X-ray Binaries are interacting binary systems composed of a compact object orbiting an O/B massive star. These objects are deeply studied with the aim of understanding accretion and ejection processes around compact objects. Recent studies claim that most of the Galactic massive stars do not live alone and suffer from mass transfer during their life. Therefore, understanding the HMXB evolution and their interaction with the close environment allows to better understand not only the evolution of massive binary stars, possible progenitors of gamma-ray bursts and gravitational waves emitters during their coalescence, but also to correctly characterize the faraway galaxies. How do these sources evolve? Where are they located in the Galaxy? What are their principal properties? What is the influence of their environment? What is their impact on the interstellar medium? This thesis aims at shedding some light on these questions, by adopting two complementary approaches: a statistical study of the Galactic population of HMXB and on another hand a multi-wavelength study of individual sources. The first part of this thesis introduces the main characteristics of massive stars. Their evolution and the observational features are described. We also present the main observational and theoretical properties of HMXB together with the multi-wavelength approach used in this work. With the aim of better understanding the stellar evolution and the connections between compact objects and supernovae or gamma-ray bursts, it is of major interest to understand where these compact objects are born. Thus, the second part details the statistical study carried out on the Galactic HMXB population. Thanks to a uniform approach based on spectral energy distribution fitting, we determine, for the first time, the distance of 46 HMXB into the Milky Way with an accurate uncertainties estimation. Then, we present the distribution of these sources in the Galaxy and we show that a correlation

Discovery of Psr J1227-4853: A Transition from a Low-mass X-Ray Binary to a Redback Millisecond Pulsar

NARCIS (Netherlands)

Roy, J.; Ray, P.S.; Bhattacharyya, B.; Stappers, B.; Chengalur, J.N.; Deneva, J.; Camilo, F.; Johnson, T.J.; Wolff, M.; Hessels, J.W.T.; Bassa, C.G.; Keane, E.F.; Ferrara, E.C.; Harding, A.K.; Wood, K.S.

2015-01-01

XSS J12270−4859 is an X-ray binary associated with the Fermi Large Area Telescope gamma-ray source 1FGL J1227.9−4852. In 2012 December, this source underwent a transition where the X-ray and optical luminosity dropped and the spectral signatures of an accretion disk disappeared. We report the

TIMING OBSERVATIONS OF PSR J1023+0038 DURING A LOW-MASS X-RAY BINARY STATE

Energy Technology Data Exchange (ETDEWEB)

Jaodand, Amruta; Archibald, Anne M.; Hessels, Jason W. T.; Bassa, Cees; Deller, Adam T. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); D’Angelo, Caroline R.; Patruno, Alessandro [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

2016-10-20

Transitional millisecond pulsars (tMSPs) switch, on roughly multi-year timescales, between rotation-powered radio millisecond pulsar (RMSP) and accretion-powered low-mass X-ray binary (LMXB) states. The tMSPs have raised several questions related to the nature of accretion flow in their LMXB state and the mechanism that causes the state switch. The discovery of coherent X-ray pulsations from PSR J1023+0038 (while in the LMXB state) provides us with the first opportunity to perform timing observations and to compare the neutron star’s spin variation during this state to the measured spin-down in the RMSP state. Whereas the X-ray pulsations in the LMXB state likely indicate that some material is accreting onto the neutron star’s magnetic polar caps, radio continuum observations indicate the presence of an outflow. The fraction of the inflowing material being ejected is not clear, but it may be much larger than that reaching the neutron star’s surface. Timing observations can measure the total torque on the neutron star. We have phase-connected nine XMM-Newton observations of PSR J1023+0038 over the last 2.5 years of the LMXB state to establish a precise measurement of spin evolution. We find that the average spin-down rate as an LMXB is 26.8 ± 0.4% faster than the rate (−2.39 × 10{sup −15} Hz s{sup −1}) determined during the RMSP state. This shows that negative angular momentum contributions (dipolar magnetic braking, and outflow) exceed positive ones (accreted material), and suggests that the pulsar wind continues to operate at a largely unmodified level. We discuss implications of this tight observational constraint in the context of possible accretion models.

High-energy emissions from the gamma-ray binary LS 5039

Energy Technology Data Exchange (ETDEWEB)

Takata, J.; Leung, Gene C. K.; Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Tam, P. H. T.; Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Hui, C. Y., E-mail: takata@hku.hk, E-mail: gene930@connect.hku.hk, E-mail: hrspksc@hku.hk [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

2014-07-20

We study mechanisms of multi-wavelength emissions (X-ray, GeV, and TeV gamma-rays) from the gamma-ray binary LS 5039. This paper is composed of two parts. In the first part, we report on results of observational analysis using 4 yr data of the Fermi Large Area Telescope. Due to the improvement of instrumental response function and increase of the statistics, the observational uncertainties of the spectrum in the ∼100-300 MeV bands and >10 GeV bands are significantly improved. The present data analysis suggests that the 0.1-100 GeV emissions from LS 5039 contain three different components: (1) the first component contributes to <1 GeV emissions around superior conjunction, (2) the second component dominates in the 1-10 GeV energy bands, and (3) the third component is compatible with the lower-energy tail of the TeV emissions. In the second part, we develop an emission model to explain the properties of the phase-resolved emissions in multi-wavelength observations. Assuming that LS 5039 includes a pulsar, we argue that emissions from both the magnetospheric outer gap and the inverse-Compton scattering process of cold-relativistic pulsar wind contribute to the observed GeV emissions. We assume that the pulsar is wrapped by two kinds of termination shock: Shock-I due to the interaction between the pulsar wind and the stellar wind and Shock-II due to the effect of the orbital motion. We propose that the X-rays are produced by the synchrotron radiation at the Shock-I region and the TeV gamma-rays are produced by the inverse-Compton scattering process at the Shock-II region.

COMMON PATTERNS IN THE EVOLUTION BETWEEN THE LUMINOUS NEUTRON STAR LOW-MASS X-RAY BINARY SUBCLASSES

International Nuclear Information System (INIS)

Fridriksson, Joel K.; Homan, Jeroen; Remillard, Ronald A.

2015-01-01

The X-ray transient XTE J1701–462 was the first source observed to evolve through all known subclasses of low-magnetic-field neutron star low-mass X-ray binaries (NS-LMXBs), as a result of large changes in its mass accretion rate. To investigate to what extent similar evolution is seen in other NS-LMXBs we have performed a detailed study of the color–color and hardness–intensity diagrams (CDs and HIDs) of Cyg X-2, Cir X-1, and GX 13+1—three luminous X-ray binaries, containing weakly magnetized neutron stars, known to exhibit strong secular changes in their CD/HID tracks. Using the full set of Rossi X-ray Timing Explorer Proportional Counter Array data collected for the sources over the 16 year duration of the mission, we show that Cyg X-2 and Cir X-1 display CD/HID evolution with close similarities to XTE J1701–462. Although GX 13+1 shows behavior that is in some ways unique, it also exhibits similarities to XTE J1701–462, and we conclude that its overall CD/HID properties strongly indicate that it should be classified as a Z source, rather than as an atoll source. We conjecture that the secular evolution of Cyg X-2, Cir X-1, and GX 13+1—illustrated by sequences of CD/HID tracks we construct—arises from changes in the mass accretion rate. Our results strengthen previous suggestions that within single sources Cyg-like Z source behavior takes place at higher luminosities and mass accretion rates than Sco-like Z behavior, and lend support to the notion that the mass accretion rate is the primary physical parameter distinguishing the various NS-LMXB subclasses

COMMON PATTERNS IN THE EVOLUTION BETWEEN THE LUMINOUS NEUTRON STAR LOW-MASS X-RAY BINARY SUBCLASSES

Energy Technology Data Exchange (ETDEWEB)

Fridriksson, Joel K. [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Homan, Jeroen; Remillard, Ronald A., E-mail: J.K.Fridriksson@uva.nl [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

2015-08-10

The X-ray transient XTE J1701–462 was the first source observed to evolve through all known subclasses of low-magnetic-field neutron star low-mass X-ray binaries (NS-LMXBs), as a result of large changes in its mass accretion rate. To investigate to what extent similar evolution is seen in other NS-LMXBs we have performed a detailed study of the color–color and hardness–intensity diagrams (CDs and HIDs) of Cyg X-2, Cir X-1, and GX 13+1—three luminous X-ray binaries, containing weakly magnetized neutron stars, known to exhibit strong secular changes in their CD/HID tracks. Using the full set of Rossi X-ray Timing Explorer Proportional Counter Array data collected for the sources over the 16 year duration of the mission, we show that Cyg X-2 and Cir X-1 display CD/HID evolution with close similarities to XTE J1701–462. Although GX 13+1 shows behavior that is in some ways unique, it also exhibits similarities to XTE J1701–462, and we conclude that its overall CD/HID properties strongly indicate that it should be classified as a Z source, rather than as an atoll source. We conjecture that the secular evolution of Cyg X-2, Cir X-1, and GX 13+1—illustrated by sequences of CD/HID tracks we construct—arises from changes in the mass accretion rate. Our results strengthen previous suggestions that within single sources Cyg-like Z source behavior takes place at higher luminosities and mass accretion rates than Sco-like Z behavior, and lend support to the notion that the mass accretion rate is the primary physical parameter distinguishing the various NS-LMXB subclasses.

Quasi-periodic oscillations and noise in low-mass X-ray binaries

International Nuclear Information System (INIS)

Van der Klis, M.

1989-01-01

The phenomenology of quasi-periodic oscillations (QPOs) and noise in low-mass X-ray binaries (LMXBs) is discussed. Signal analysis aspects of QPO and noise are addressed along with the relationship between LMXBs and millisecond radio pulsars. The history and prehistory of QPOs and noise in LMXBs are examined. Universal noise components and normal and flaring branch QPOs in Z sources are described and the phenomenology of Z sources is discussed. Bright LMXBs known as atoll sources are considered, as are nonpersistently bright LMXBs accreting pulsars and black hole candidates. 162 refs

SS433: the second Wolf-Rayet X-ray binary ?

OpenAIRE

Fuchs, Yael; Koch-Miramond, Lydie; Abraham, Peter

2002-01-01

We present mid-infrared spectrophotometric observations of SS433 with ISOPHOT. The HeI+HeII lines in both spectra of SS433 and of the Wolf-Rayet star WR147, a wind-colliding WN8+BO5 binary system, closely match. The 2.5-12 micron continuum radiation is due to an expanding wind free-free emission in an intermediate case between optically thick and optically thin regimes. The inferred mass loss rate evaluation gives ~10^{-4} Msun/yr. Our results are consistent with a Wolf-Rayet-like companion t...

Novel X-ray telescopes for wide-field X-ray monitoring

International Nuclear Information System (INIS)

Hudec, R.; Inneman, A.; Pina, L.; Sveda, L.

2005-01-01

We report on fully innovative very wide-field of view X-ray telescopes with high sensitivity as well as large field of view. The prototypes are very promising, allowing the proposals for space projects with very wide-field Lobster-eye X-ray optics to be considered. The novel telescopes will monitor the sky with unprecedented sensitivity and angular resolution of order of 1 arcmin. They are expected to contribute essentially to study and to understand various astrophysical objects such as AGN, SNe, Gamma-ray bursts (GRBs), X-ray flashes (XRFs), galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc. The Lobster optics based X-ray All Sky Monitor is capable to detect around 20 GRBs and 8 XRFs yearly and this will surely significantly contribute to the related science

Optical and X-ray luminosities of expanding nebulae around ultraluminous X-ray sources

Science.gov (United States)

Siwek, Magdalena; Sądowski, Aleksander; Narayan, Ramesh; Roberts, Timothy P.; Soria, Roberto

2017-09-01

We have performed a set of simulations of expanding, spherically symmetric nebulae inflated by winds from accreting black holes in ultraluminous X-ray sources (ULXs). We implemented a realistic cooling function to account for free-free and bound-free cooling. For all model parameters we considered, the forward shock in the interstellar medium becomes radiative at a radius ˜100 pc. The emission is primarily in optical and UV, and the radiative luminosity is about 50 per cent of the total kinetic luminosity of the wind. In contrast, the reverse shock in the wind is adiabatic so long as the terminal outflow velocity of the wind vw ≳ 0.003c. The shocked wind in these models radiates in X-rays, but with a luminosity of only ˜1035 erg s-1. For wind velocities vw ≲ 0.001c, the shocked wind becomes radiative, but it is no longer hot enough to produce X-rays. Instead it emits in optical and UV, and the radiative luminosity is comparable to 100 per cent of the wind kinetic luminosity. We suggest that measuring the optical luminosities and putting limits on the X-ray and radio emission from shock-ionized ULX bubbles may help in estimating the mass outflow rate of the central accretion disc and the velocity of the outflow.

Young and Old X-ray Binary and IXO Populations in Spiral and Elliptical Galaxies

Science.gov (United States)

Colbert, E.; Heckman, T.; Ptak, A.; Strickland, D.; Weaver, K.

2003-03-01

We have analyzed Chandra ACIS observations of 32 nearby spiral and elliptical galaxies and present the results of 1441 X-ray point sources, which are presumed to be mostly X-ray binaries (XRBs) and Intermediate-luminosity X-ray Objects (IXOs, a.k.a. ULXs). The X-ray luminosity functions (XLFs) of the point sources show that the slope of the elliptical galaxy XLFs are significantly steeper than the spiral galaxy XLFs, indicating grossly different types of point sources, or different stages in their evolution. Since the spiral galaxy XLF is so shallow, the most luminous points sources (usually the IXOs) dominate the total X-ray point source luminosity LXP. We show that the galaxy total B-band and K-band light (proxies for the stellar mass) are well correlated with LXP for both spirals and ellipticals, but the FIR and UV emission is only correlated for the spirals. We deconvolve LXP into two components, one that is proportional to the galaxy stellar mass (pop II), and another that is proportional to the galaxy SFR (pop I). We also note that IXOs (and nearly all of the other point sources) in both spirals and ellipticals have X-ray colors that are most consistent with power-law slopes of Gamma ˜ 1.5--3.0, which is inconsistent with high-mass XRBS (HMXBs). Thus, HMXBs are not important contributors to LXP. We have also found that IXOs in spiral galaxies may have a slightly harder X-ray spectrum than those in elliptical galaxies. The implications of these findings will be discussed.

RXTE detects X-ray bursts from Circinus X-1

NARCIS (Netherlands)

Linares, M.; Soleri, P.; Watts, A.; Altamirano, D.; Armas-Padilla, M.; Cavecchi, Y.; Degenaar, N.; Kalamkar, M.; Kaur, R.; van der Klis, M.; Patruno, A.; Wijnands, R.; Yang, Y.; Casella, P.; Rea, N.

After the recent report of X-ray re-brightening (ATel #2608), RXTE has observed the peculiar neutron star X-ray binary Cir X-1 eleven times during the last two weeks (May 11-25, 2010). We report the detection of nine X-ray bursts in RXTE-PCA data, 25 years after the first -and the only previous-

A LUMINOUS GAMMA-RAY BINARY IN THE LARGE MAGELLANIC CLOUD

Energy Technology Data Exchange (ETDEWEB)

Corbet, R. H. D. [University of Maryland, Baltimore County, and X-ray Astrophysics Laboratory, Code 662 NASA Goddard Space Flight Center, Greenbelt Rd., MD 20771 (United States); Chomiuk, L.; Strader, J. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Coe, M. J. [University of Southampton, School of Physics and Astronomy, Southampton SO17 1BJ (United Kingdom); Coley, J. B. [NASA Postdoctoral Program, and Astroparticle Physics Laboratory, Code 661 NASA Goddard Space Flight Center, Greenbelt Rd., MD 20771 (United States); Dubus, G. [Institut de Planétologie et d’Astrophysique de Grenoble, Univ. Grenoble Alpes, CNRS, F-38000 Grenoble (France); Edwards, P. G.; Stevens, J. [Commonwealth Scientific and Industrial Research Organisation Astronomy and Space Science, P.O. Box 76, Epping, New South Wales 1710 (Australia); Martin, P. [Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, F-31028 Toulouse cedex 4 (France); McBride, V. A.; Townsend, L. J. [Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa); Udalski, A. [Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland)

2016-10-01

Gamma-ray binaries consist of a neutron star or a black hole interacting with a normal star to produce gamma-ray emission that dominates the radiative output of the system. Only a handful of such systems have been previously discovered, all within our Galaxy. Here, we report the discovery of a luminous gamma-ray binary in the Large Magellanic Cloud, found with the Fermi Large Area Telescope (LAT), from a search for periodic modulation in all sources in the third Fermi LAT catalog. This is the first such system to be found outside the Milky Way. The system has an orbital period of 10.3 days, and is associated with a massive O5III star located in the supernova remnant DEM L241, previously identified as the candidate high-mass X-ray binary (HMXB) CXOU J053600.0–673507. X-ray and radio emission are also modulated on the 10.3 day period, but are in anti-phase with the gamma-ray modulation. Optical radial velocity measurements suggest that the system contains a neutron star. The source is significantly more luminous than similar sources in the Milky Way, at radio, optical, X-ray, and gamma-ray wavelengths. The detection of this extra-galactic system, but no new Galactic systems, raises the possibility that the predicted number of gamma-ray binaries in our Galaxy has been overestimated, and that HMXBs may be born containing relatively slowly rotating neutron stars.

X-ray emission due to interaction of SN1987A ejecta with its progenitor's stellar-wind matter

International Nuclear Information System (INIS)

Masai, Kuniaki.

1990-06-01

The progenitor of the supernova 1987A, Sk-69 202 probably had lost a considerable amount of mass in its stellar wind in the past evolutionary track through a red supergiant to a blue supergiant. In about 10 years, the expanding ejecta of SN1987A will catch up to collide with the wind matter ejected in the red supergiant phase. Shocks due to the collision will heat up the ejecta and the wind matter to cause an enhancement of thermal X-ray emission lasting for several decades. We predict the X-ray light curve and the spectrum as well as the epoch of the enhancement intending to encourage future X-ray observations, which will give a clue for the study of such peculiar stellar evolution with a blueward transition as Sk-69 202. (author)

Intense soft x-rays from RS Ophiuchi during the 1985 outburst

International Nuclear Information System (INIS)

Mason, K.O.; Cordova, F.A.; Bode, M.F.; Barr, P.

1985-01-01

Intense soft x-ray emission with a characteristic temperature of a few million degrees has been detected from the recurrent nova RS Oph approximately two months after its January 1985 optical outburst. This is the first detection of x-rays from such a system at outburst. The x-radiation is interpreted as emission from circumstellar gas that is shock heated by the passage of the blast wave from the nova explosion. The rapid decline of the x-ray flux between about 60 and 90 days after the outburst probably occurs because the blast wave has reached the edge of the volume filled, between outbursts, by the stellar wind of the red giant component of the binary system. Residual x-ray emission detected from RS Oph 250 days after the outburst is interpreted as coming from the surface of a white dwarf, at a temperature of approx.300,000K, where thermonuclear burning is persisting. 7 refs., 3 figs

Phase-Resolved Spectroscopy of the Low-Mass X-ray Binary V801 Ara

Science.gov (United States)

Brauer, Kaley; Vrtilek, Saeqa Dil; Peris, Charith; McCollough, Michael

2018-06-01

We present phase-resolved optical spectra of the low mass X-ray binary system V801 Ara. The spectra, obtained in 2014 with IMACS on the Magellan/Baade telescope at Las Campanas Observatory, cover the full binary orbit of 3.8 hours. They contain strong emission features allowing us to map the emission of Hα, Hβ, He II λ4686, and the Bowen blend at λ4640. The radial velocity curves of the Bowen blend shows significantly stronger modulation at the orbital period than Hα as expected for the former originating on the secondary with the latter consistent with emission dominated by the disk. Our tomograms of Hα and Hβ are the most detailed studies of these lines for V801 to date and they clearly detect the accretion disk. The Hβ emission extends to higher velocities than Hα, suggesting emission from closer to the neutron star and differentiating temperature variance in the accretion disk for the first time. The center of the accretion disk appears offset from the center-of-mass of the neutron star as has been seen in several other X-ray binaries. This is often interpreted to imply disk eccentricity. Our tomograms do not show strong evidence for a hot spot at the point where the accretion stream hits the disk. This could imply a reduced accretion rate or could be due to the spot being drowned out by bright accretion flow around it. There is enhanced emission further along the disk, however, which implies gas stream interaction downstream of the hot spot.

A fast search strategy for gravitational waves from low-mass x-ray binaries

International Nuclear Information System (INIS)

Messenger, C; Woan, G

2007-01-01

We present a new type of search strategy designed specifically to find continuously emitting gravitational wave sources in known binary systems. A component of this strategy is based on the incoherent summation of frequency-modulated binary signal sidebands, a method previously employed in the detection of electromagnetic pulsar signals from radio observations. The search pipeline can be divided into three stages: the first is a wide bandwidth, F-statistic search demodulated for sky position. This is followed by a fast second stage in which areas in frequency space are identified as signal candidates through the frequency domain convolution of the F-statistic with an approximate signal template. For this second stage only precise information on the orbit period and approximate information on the orbital semi-major axis are required a priori. For the final stage we propose a fully coherent Markov chain Monte Carlo based follow-up search on the frequency subspace defined by the candidates identified by the second stage. This search is particularly suited to the low-mass x-ray binaries, for which orbital period and sky position are typically well known and additional orbital parameters and neutron star spin frequency are not. We note that for the accreting x-ray millisecond pulsars, for which spin frequency and orbital parameters are well known, the second stage can be omitted and the fully coherent search stage can be performed. We describe the search pipeline with respect to its application to a simplified phase model and derive the corresponding sensitivity of the search

Marriage of x-ray and optical astronomy

International Nuclear Information System (INIS)

McClintock, J.E.

1975-01-01

An historical discussion of the relation of x-ray and optical astronomy is given including distances within our galaxy, the optical identification of x-ray sources, the binary x-ray stars, neutron stars and black holes, a program in x-ray astronomy, and future missions

Classification of X-ray sources in the direction of M31

Science.gov (United States)

Vasilopoulos, G.; Hatzidimitriou, D.; Pietsch, W.

2012-01-01

M31 is our nearest spiral galaxy, at a distance of 780 kpc. Identification of X-ray sources in nearby galaxies is important for interpreting the properties of more distant ones, mainly because we can classify nearby sources using both X-ray and optical data, while more distant ones via X-rays alone. The XMM-Newton Large Project for M31 has produced an abundant sample of about 1900 X-ray sources in the direction of M31. Most of them remain elusive, giving us little signs of their origin. Our goal is to classify these sources using criteria based on properties of already identified ones. In particular we construct candidate lists of high mass X-ray binaries, low mass X-ray binaries, X-ray binaries correlated with globular clusters and AGN based on their X-ray emission and the properties of their optical counterparts, if any. Our main methodology consists of identifying particular loci of X-ray sources on X-ray hardness ratio diagrams and the color magnitude diagrams of their optical counterparts. Finally, we examined the X-ray luminosity function of the X-ray binaries populations.

THE RADIATIVE X-RAY AND GAMMA-RAY EFFICIENCIES OF ROTATION-POWERED PULSARS

International Nuclear Information System (INIS)

Vink, Jacco; Bamba, Aya; Yamazaki, Ryo

2011-01-01

We present a statistical analysis of the X-ray luminosity of rotation-powered pulsars and their surrounding nebulae using the sample of Kargaltsev and Pavlov, and we complement this with an analysis of the γ-ray emission of Fermi-detected pulsars. We report a strong trend in the efficiency with which spin-down power is converted to X-ray and γ-ray emission with characteristic age: young pulsars and their surrounding nebulae are efficient X-ray emitters, whereas in contrast old pulsars are efficient γ-ray emitters. We divided the X-ray sample in a young (τ c 4 yr) and old sample and used linear regression to search for correlations between the logarithm of the X-ray and γ-ray luminosities and the logarithms of the periods and period derivatives. The X-ray emission from young pulsars and their nebulae are both consistent with L X ∝ P-dot 3 /P 6 . For old pulsars and their nebulae the X-ray luminosity is consistent with a more or less constant efficiency η≡L X / E-dot rot ∼8x10 -5 . For the γ-ray luminosity we confirm that L γ ∝ √E-dot rot . We discuss these findings in the context of pair production inside pulsar magnetospheres and the striped wind model. We suggest that the striped wind model may explain the similarity between the X-ray properties of the pulsar wind nebulae and the pulsars themselves, which according to the striped wind model may both find their origin outside the light cylinder, in the pulsar wind zone.

TRACING THE REVERBERATION LAG IN THE HARD STATE OF BLACK HOLE X-RAY BINARIES

International Nuclear Information System (INIS)

De Marco, B.; Ponti, G.; Nandra, K.; Muñoz-Darias, T.

2015-01-01

We report results obtained from a systematic analysis of X-ray lags in a sample of black hole X-ray binaries, with the aim of assessing the presence of reverberation lags and studying their evolution during outburst. We used XMM-Newton and simultaneous Rossi X-ray Timing Explorer (RXTE) observations to obtain broadband energy coverage of both the disk and the hard X-ray Comptonization components. In most cases the detection of reverberation lags is hampered by low levels of variability-power signal-to-noise ratio (typically when the source is in a soft state) and/or short exposure times. The most detailed study was possible for GX 339-4 in the hard state, which allowed us to characterize the evolution of X-ray lags as a function of luminosity in a single source. Over all the sampled frequencies (∼0.05–9 Hz), we observe the hard lags intrinsic to the power-law component, already well known from previous RXTE studies. The XMM-Newton soft X-ray response allows us to detail the disk variability. At low frequencies (long timescales) the disk component always leads the power-law component. On the other hand, a soft reverberation lag (ascribable to thermal reprocessing) is always detected at high frequencies (short timescales). The intrinsic amplitude of the reverberation lag decreases as the source luminosity and the disk fraction increase. This suggests that the distance between the X-ray source and the region of the optically thick disk where reprocessing occurs gradually decreases as GX 339-4 rises in luminosity through the hard state, possibly as a consequence of reduced disk truncation

Fermi-LAT upper limits on gamma-ray emission from colliding wind binaries

International Nuclear Information System (INIS)

Werner, Michael; Reimer, O.; Reimer, A.

2013-01-01

Here, colliding wind binaries (CWBs) are thought to give rise to a plethora of physical processes including acceleration and interaction of relativistic particles. Observation of synchrotron radiation in the radio band confirms there is a relativistic electron population in CWBs. Accordingly, CWBs have been suspected sources of high-energy γ-ray emission since the COS-B era. Theoretical models exist that characterize the underlying physical processes leading to particle acceleration and quantitatively predict the non-thermal energy emission observable at Earth. Furthermore, we strive to find evidence of γ-ray emission from a sample of seven CWB systems: WR 11, WR 70, WR 125, WR 137, WR 140, WR 146, and WR 147. Theoretical modelling identified these systems as the most favourable candidates for emitting γ-rays. We make a comparison with existing γ-ray flux predictions and investigate possible constraints. We used 24 months of data from the Large Area Telescope (LAT) on-board the Fermi Gamma Ray Space Telescope to perform a dedicated likelihood analysis of CWBs in the LAT energy range. As a result, we find no evidence of γ-ray emission from any of the studied CWB systems and determine corresponding flux upper limits. For some CWBs the interplay of orbital and stellar parameters renders the Fermi-LAT data not sensitive enough to constrain the parameter space of the emission models. In the cases of WR140 and WR147, the Fermi-LAT upper limits appear to rule out some model predictions entirely and constrain theoretical models over a significant parameter space. A comparison of our findings to the CWB η Car is made.

DISCOVERY OF X-RAY EMISSION FROM THE FIRST Be/BLACK HOLE SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Munar-Adrover, P.; Paredes, J. M.; Ribó, M. [Departament d' Astronomia i Meteorologia, Institut de Ciències del Cosmos, Universitat de Barcelona, IEEC-UB, Martí i Franquès 1, E-08028 Barcelona (Spain); Iwasawa, K. [ICREA, Institut de Ciències del Cosmos, Universitat de Barcelona, IEEC-UB, Martí i Franquès 1, E-08028 Barcelona (Spain); Zabalza, V. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Casares, J. [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain)

2014-05-10

MWC 656 (=HD 215227) was recently discovered to be the first binary system composed of a Be star and a black hole (BH). We observed it with XMM-Newton, and detected a faint X-ray source compatible with the position of the optical star, thus proving it to be the first Be/BH X-ray binary. The spectrum analysis requires a model fit with two components, a blackbody plus a power law, with k{sub B}T=0.07{sub −0.03}{sup +0.04} keV and a photon index Γ = 1.0 ± 0.8, respectively. The non-thermal component dominates above ≅0.8 keV. The obtained total flux is F(0.3-5.5 keV)=(4.6{sub −1.1}{sup +1.3})×10{sup −14} erg cm{sup –2} s{sup –1}. At a distance of 2.6 ± 0.6 kpc the total flux translates into a luminosity L {sub X} = (3.7 ± 1.7) × 10{sup 31} erg s{sup –1}. Considering the estimated range of BH masses to be 3.8-6.9 M {sub ☉}, this luminosity represents (6.7 ± 4.4) × 10{sup –8} L {sub Edd}, which is typical of stellar-mass BHs in quiescence. We discuss the origin of the two spectral components: the thermal component is associated with the hot wind of the Be star, whereas the power-law component is associated with emission from the vicinity of the BH. We also find that the position of MWC 656 in the radio versus X-ray luminosity diagram may be consistent with the radio/X-ray correlation observed in BH low-mass X-ray binaries. This suggests that this correlation might also be valid for BH high-mass X-ray binaries (HMXBs) with X-ray luminosities down to ∼10{sup –8} L {sub Edd}. MWC 656 will allow the accretion processes and the accretion/ejection coupling at very low luminosities for BH HMXBs to be studied.

Broad-band monitoring tracing the evolution of the jet and disc in the black hole candidate X-ray binary MAXI J1659-152

NARCIS (Netherlands)

van der Horst, A.J.; Curran, P.A.; Miller-Jonis, J.C.A.; Linford, J.D.; Gorosabel, J.; Russell, D.M.; De Ugarte Postigo, A.; Lundgren, A.A.; Taylor, G.B.; Maitra, D.; Guziy, S.; Belloni, T.M.; Kouveliotou, C.; Jonker, P.G.; Kamble, A.; Paragi, Z.; Homan, J.; Kuulkers, E.; Granot, J.; Altamirano, D.; Buxton, M.M.; Castro-Tirado, A.; Fender, R.P.; Garret, M.A.; Gehrels, N.; Hartmann, D.H.; Kennea, J.A.; Krimm, H.A.; Mangano, V.; Ramirez-Ruiz, E.; Romano, P.; Wijers, R.A.M.J.; Wijnands, R.; Yang, Y.J.

2013-01-01

MAXI J1659−152 was discovered on 2010 September 25 as a new X-ray transient, initially identified as a gamma-ray burst, but was later shown to be a new X-ray binary with a black hole as the most likely compact object. Dips in the X-ray light curves have revealed that MAXI J1659−152 is the shortest

Revising the Local Bubble Model due to Solar Wind Charge Exchange X-ray Emission

Science.gov (United States)

Shelton, Robin L.

2009-03-01

The hot Local Bubble surrounding the solar neighborhood has been primarily studied through observations of its soft X-ray emission. The measurements were obtained by attributing all of the observed local soft X-rays to the bubble. However, mounting evidence shows that the heliosphere also produces diffuse X-rays. The source is solar wind ions that have received an electron from another atom. The presence of this alternate explanation for locally produced diffuse X-rays calls into question the existence and character of the Local Bubble. This article addresses these questions. It reviews the literature on solar wind charge exchange (SWCX) X-ray production, finding that SWCX accounts for roughly half of the observed local 1/4 keV X-rays found at low latitudes. This article also makes predictions for the heliospheric O VI column density and intensity, finding them to be smaller than the observational error bars. Evidence for the continued belief that the Local Bubble contains hot gas includes the remaining local 1/4 keV intensity, the observed local O VI column density, and the need to fill the local region with some sort of plasma. If the true Local Bubble is half as bright as previously thought, then its electron density and thermal pressure are 1/sqrt{2} as great as previously thought, and its energy requirements and emission measure are 1/2 as great as previously thought. These adjustments can be accommodated easily, and, in fact, bring the Local Bubble’s pressure more in line with that of the adjacent material. Suggestions for future work are made.

X-ray astronomy

International Nuclear Information System (INIS)

Culhane, J.L.; Sanford, P.W.

1981-01-01

X-ray astronomy has been established as a powerful means of observing matter in its most extreme form. The energy liberated by sources discovered in our Galaxy has confirmed that collapsed stars of great density, and with intense gravitational fields, can be studied by making observations in the X-ray part of the electromagnetic spectrum. The astronomical objects which emit detectable X-rays include our own Sun and extend to quasars at the edge of the Universe. This book describes the history, techniques and results obtained in the first twenty-five years of exploration. Space rockets and satellites are essential for carrying the instruments above the Earth's atmosphere where it becomes possible to view the X-rays from stars and nebulae. The subject is covered in chapters, entitled: the birth of X-ray astronomy; the nature of X-radiation; X-rays from the Sun; solar-flare X-rays; X-rays from beyond the solar system; supernovae and their remnants; X-rays from binary stars; white dwarfs and neutron stars; black holes; X-rays from galaxies and quasars; clusters of galaxies; the observatories of the future. (author)

Revealing fatigue damage evolution in unidirectional composites for wind turbine blades using x-ray computed tomography

DEFF Research Database (Denmark)

Mikkelsen, Lars Pilgaard

’. Thereby, it will be possible to lower the cost of energy for wind energy based electricity. In the presented work, a lab-source x-ray computed tomography equipment (Zeiss Xradia 520 Versa) has been used in connection with ex-situ fatigue testing of uni-directional composites in order to identify fibre...... to other comparable x-ray studies) have been used in order to ensure a representative test volume during the ex-situ fatigue testing. Using the ability of the x-ray computed tomography to zoom into regions of interest, non-destructive, the fatigue damage evolution in a repeating ex-situ fatigue loaded test...... improving the fatigue resistance of non-crimp fabric used in the wind turbine industry can be made....

Mass estimates from optical-light curves for binary X-ray sources

International Nuclear Information System (INIS)

Avni, Y.

1978-01-01

The small amplitude variations with orbital phase of the optical light from X-ray binaries are caused by the changing geometrical aspect of the primary as seen by a fixed observer. The shape and the amplitude of the light curve depends on the stellar masses and on the orbital elements. The light curve can, therefore, be used to determine, or set limits on, the parameters of the binary system. A self-consistent procedure for the calculation of the light curve can be formulated if the primary is formulated if the primary is uniformly rotating at an angular velocity equal to the angular velocity of its orbital revolution in a circular orbit, and if the primary is in a hydrostatic and radiative equilibrium in the co-rotating frame. When the primary is further approximated to be centrally condensed, the above set of assumptions is called the standard picture. The standard picture is described, its validity discussed and its application to various systems reviewed. (C.F.)

X-ray bursters and the X-ray sources of the galactic bulge

International Nuclear Information System (INIS)

Lewin, W.H.G.; Joss, P.C.; Massachusetts Inst. of Tech., Cambridge; Massachusetts Inst. of Tech., Cambridge

1981-01-01

In this article we shall discuss the observed X-ray, optical, infrared and radio properties of the galactic bulge sources, with an emphasis on those that produce type I X-ray bursts. There is persuasive evidence that these burst sources and many other galactic bulge sources are neutron stars in low-mass, close-binary stellar systems. (orig./WL)

100y DASCH Search for historical outbursts of Black Hole Low Mass X-ray Binaries

Science.gov (United States)

Grindlay, Jonathan E.; Miller, George; Gomez, Sebastian

2018-01-01

Black Hole Low mass X-ray binaries (BH-LMXBs) are all transients, although several (e.g. GRS1915+109 and GX339-4) are quasi-persistent. All of the now 22 dynamically confirmed BH-LMXBs were discovered by their luminous outbursts, reaching Lx ~10^37 ergs/s, with outburst durations of typically ~1-3 months. These systems then (with few exceptions) return to a deep quiescent state, with Lx reduced by factors ~10^5-6 and hard X-ray spectra. The X-ray outbursts are accompanied by optical outbursts (if not absorbed by Galactic extinction) with ~6-9 magnitude increases and similar lightcurve shapes and durations as the X-ray (discovery) outburst. Prior to this work, only 3 BH-LMXBs have had historical (before the X-ray discovery) outbursts found in the archival data: A0620-00, the first BH-LMXB to be so identified, V404 Cyg (discoverd as "Nova Cyg" in 1938 and regarded as a classical nova), and V4641-Sgr which was given its variable star name when first noted in 1975. We report on the historical outbursts now discovered from the DASCH (Digital Access to a Sky Century @ Harvard) data from scanning and digitizing the now ~210,000 glass plates in the northern Galactic Hemisphere. This was one of the primary motivations for the DASCH project: to use the detection (or lack threof) of historic outbursts to measure or constrain the Duty Cycle of the accreting black holes in these systems. This, in turn, allows the total population of BH-LMXBs to be estimated and compared with that for the very similar systems containing neutron stars as the accretor (NS-LMXBs). Whereas the ratio of BHs/NSs from stellar evolution and IMFs is expected to be <<1, the DASCH results on half the sky point to an excess of BH-LMXBs. This must constrain the formation process for these systems, of importance for understanding both BH formation and compact binary evolution.

Swift-XRT detects X-ray burst from Circinus X-1

NARCIS (Netherlands)

Linares, M.; Soleri, P.; Altamirano, D.; Armas-Padilla, M.; Cavecchi, Y.; Degenaar, N.; Kalamkar, M.; Kaur, R.; van der Klis, M.; Patruno, A.; Watts, A.; Wijnands, R.; Yang, Y.; Casella, P.; Rea, N.; Chakrabarty, D.; Homan, J.

Following the recent re-brightening (ATel #2608) and RXTE-PCA detection of X-ray bursts from the peculiar X-ray binary Cir X-1 between May 15 and 25 (ATel #2643), we obtained a series of Swift-XRT observations of the field (see also ATel #2650). Swift-XRT detected an X-ray burst on 2010-05-28 at

A Self-consistent Model for a Full Cycle of Recurrent Novae—Wind Mass-loss Rate and X-Ray Luminosity

Energy Technology Data Exchange (ETDEWEB)

Kato, Mariko [Department of Astronomy, Keio University, Hiyoshi, Yokohama 223-8521 (Japan); Saio, Hideyuki [Astronomical Institute, Graduate School of Science, Tohoku University, Sendai, 980-8578 (Japan); Hachisu, Izumi, E-mail: mariko.kato@hc.st.keio.ac.jp [Department of Earth Science and Astronomy, College of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902 (Japan)

2017-04-01

An unexpectedly slow evolution in the pre-optical-maximum phase was suggested in the very short recurrence period of nova M31N 2008-12a. To obtain reasonable nova light curves we have improved our calculation method by consistently combining optically thick wind solutions of hydrogen-rich envelopes with white dwarf (WD) structures calculated by a Henyey-type evolution code. The wind mass-loss rate is properly determined with high accuracy. We have calculated light curve models for 1.2 M {sub ⊙} and 1.38 M {sub ⊙} WDs with mass accretion rates corresponding to recurrence periods of 10 yr and 1 yr, respectively. The outburst lasts 590/29 days, in which the pre-optical-maximum phase is 82/16 days, for 1.2/1.38 M {sub ⊙}, respectively. Optically thick winds start at the end of the X-ray flash and cease at the beginning of the supersoft X-ray phase. We also present supersoft X-ray light curves including a prompt X-ray flash and later supersoft X-ray phase.

The 5 Hour Pulse Period and Broadband Spectrum of the Symbiotic X-Ray Binary 3A 1954+319

Science.gov (United States)

Marcu, Diana M.; Fuerst, Felix; Pottschmidt, Katja; Grinberg, Victoria; Miller, Sebstian; Wilms, Joern; Postnov, Konstantin A.; Corbet, Robin H. D.; Markwardt, Craig B.; Cadolle Bel, Marion

2011-01-01

We present an analysis of the highly variable accreting X-ray pulsar 3A 1954+319 using 2005-2009 monitoring data obtained with INTEGRAL and Swift. This considerably extends the pulse period history and covers flaring episodes in 2005 and 2008. In 2006 the source was identified as one of only a few known symbiotic X-ray binaries, Le" systems composed of a neutron star accreting from the inhomogeneous medium around an M-giant star. The extremely long pulse period of approximately 5.3 h is directly visible in the 2008 INTEGRAL-ISGRI outburst light curve. The pulse profile is double peaked and not significantly energy dependent. During the outburst a strong spin-up of -1.8 x 10(exp -4) h h(exp -1) occurred. Between 2005 and 2008 a long term spin-down trend of 2.1 x 10(exp -5) h h(exp -1) was observed for the first time for this source. The 3-80 keV pulse peak spectrum of 3A 1954+319 during the 2008 flare could be well described by a thermal Comptonization model. We interpret the results within the framework of a recently developed quasi-spherical accretion model for symbiotic X-ray binaries.

TRACING THE LOWEST PROPELLER LINE IN MAGELLANIC HIGH-MASS X-RAY BINARIES

Energy Technology Data Exchange (ETDEWEB)

Christodoulou, Dimitris M.; Laycock, Silas G. T.; Yang, Jun; Fingerman, Samuel, E-mail: dimitris_christodoulou@uml.edu, E-mail: silas_laycock@uml.edu, E-mail: jun_yang@uml.edu, E-mail: fingerman.samuel@gmail.com [Lowell Center for Space Science and Technology, 600 Suffolk Street, Lowell, MA 01854 (United States)

2016-09-20

We have combined the published observations of high-mass X-ray binary (HMXB) pulsars in the Magellanic Clouds with a new processing of the complete archival data sets from the XMM-Newton and Chandra observatories in an attempt to trace the lowest propeller line below which accretion to polar caps is inhibited by the centrifugal force and the pulsations from the most weakly magnetized pulsars cease. Previously published data reveal that some of the faster-spinning pulsars with spin periods of P {sub S} < 12 s, detected at relatively low X-ray luminosities L {sub X} , appear to define such a line in the P {sub S} – L {sub X} diagram, characterized by a magnetic moment of μ = 3 × 10{sup 29} G cm{sup 3}. This value implies the presence of surface magnetic fields of B ≥ 3 × 10{sup 11} G in the compact objects of this class. Only a few quiescent HMXBs are found below the propeller line: LXP4.40 and SXP4.78, for which XMM-Newton and Chandra null detections respectively placed firm upper limits on their X-ray fluxes in deep quiescence; and A0538-66, for which many sub-Eddington detections have never measured any pulsations. On the other hand, the data from the XMM-Newton and Chandra archives show clearly that, during routine observation cycles, several sources have been detected below the propeller line in extremely faint, nonpulsating states that can be understood as the result of weak magnetospheric emission when accretion to the poles is centrifugally stalled or severely diminished. We also pay attention to the anomalous X-ray pulsar CXOU J010043.1-721134 that was reported in HMXB surveys. Its pulsations and locations near and above the propeller line indicate that this pulsar could be accreting from a fossil disk.

Infrared, radio, and x-ray observations of Cygnus X-3

International Nuclear Information System (INIS)

Becklin, E.E.; Hawkins, F.J.; Mason, K.O.; Matthews, K.; Neugebauer, G.; Packman, D.; Sanford, P.W.; Schupler, B.; Stark, A.; Wynn-Williams, C.G.

1974-01-01

The x-ray source Cygnus X-3 has been interpreted as being a binary system on the basis of extensive x-ray observations of periodic variability. At radio wavelengths, the source displays erratic outbursts. Cyg x-3 has not been detected visually but at infrared wavelengths periodic variations in phase with the x-ray variations have been reported. Infrared, x-ray and radio observations of Cyg X-3 made during 1973 through 1973 October are presented. (U.S.)

Rossi X-Ray Timing Explorer Observations of the First Transient Z Source XTE J1701-462: Shedding New Light on Mass Accretion in Luminous Neutron Star X-Ray Binaries

Science.gov (United States)

Homan, Jeroen; van der Klis, Michiel; Wijnands, Rudy; Belloni, Tomaso; Fender, Rob; Klein-Wolt, Marc; Casella, Piergiorgio; Méndez, Mariano; Gallo, Elena; Lewin, Walter H. G.; Gehrels, Neil

2007-02-01

We report on the first 10 weeks of RXTE observations of the X-ray transient XTE J1701-462 and conclude that it had all the characteristics of the neutron star Z sources, i.e., the brightest persistent neutron star low-mass X-ray binaries. These include the typical Z-shaped tracks traced out in X-ray color diagrams and the variability components detected in the power spectra, such as kHz QPOs and normal and horizontal branch oscillations. XTE J1701-462 is the first transient Z source and provides unique insights into mass accretion rate (m˙) and luminosity dependencies in neutron star X-ray binaries. As its overall luminosity decreased, we observed a switch between two types of Z source behavior, with the branches of the Z track changing their shape and/or orientation. We interpret this as an extreme case of the more moderate long-term changes seen in the persistent Z sources and suggest that they result from changes in m˙. We also suggest that the Cyg-like Z sources (Cyg X-2, GX 5-1, and GX 340+0) are substantially more luminous (>50%) than the Sco-like Z sources (Sco X-1, GX 17+2, and GX 349+2). Adopting a possible explanation for the behavior of kHz QPOs, which involves a prompt as well as a filtered response to changes in m˙, we further propose that changes in m˙ can explain both movement along the Z track and changes in the shape of the Z track. We discuss some consequences of this and consider the possibility that the branches of the Z will smoothly evolve into the branches observed in X-ray color diagrams of the less luminous atoll sources, although not in a way that was previously suggested.

The Radiative X-ray and Gamma-ray Efficiencies of Rotation-powered Pulsars

Science.gov (United States)

Vink, Jacco; Bamba, Aya; Yamazaki, Ryo

2011-02-01

We present a statistical analysis of the X-ray luminosity of rotation-powered pulsars and their surrounding nebulae using the sample of Kargaltsev & Pavlov, and we complement this with an analysis of the γ-ray emission of Fermi-detected pulsars. We report a strong trend in the efficiency with which spin-down power is converted to X-ray and γ-ray emission with characteristic age: young pulsars and their surrounding nebulae are efficient X-ray emitters, whereas in contrast old pulsars are efficient γ-ray emitters. We divided the X-ray sample in a young (τ c < 1.7 × 104 yr) and old sample and used linear regression to search for correlations between the logarithm of the X-ray and γ-ray luminosities and the logarithms of the periods and period derivatives. The X-ray emission from young pulsars and their nebulae are both consistent with L_X ∝ \\dot{P}^3/P^6. For old pulsars and their nebulae the X-ray luminosity is consistent with a more or less constant efficiency η ≡ L_X/\\dot{E}_{rot} ≈ 8× 10^{-5}. For the γ-ray luminosity we confirm that L_γ ∝ √{\\dot{E}_{rot}}. We discuss these findings in the context of pair production inside pulsar magnetospheres and the striped wind model. We suggest that the striped wind model may explain the similarity between the X-ray properties of the pulsar wind nebulae and the pulsars themselves, which according to the striped wind model may both find their origin outside the light cylinder, in the pulsar wind zone.

Enhanced X-ray yields in PIXE analysis of some binary metal fluorides

International Nuclear Information System (INIS)

Peisach, M.; Pineda, C.A.; Pillay, A.E.

1993-01-01

Enhanced X-ray yields from the metal components of homogeneous thick targets of binary metal fluorides were observed during PIXE irradiations with protons, deuterons and 3 He ions. The absence of these effects in the pure metals and in the corresponding metal oxides, nitrides and borides suggests that the fluoride component in such compounds plays a key role in producing the enhancement. Coulomb excitation of the extremely low-lying levels of the fluorine nucleus is discussed as a possible mechanism for the improved yields via secondary excitation. (orig.)

Probing the Mysteries of the X-Ray Binary 4U 1210-64 with ASM, MAXI and Suzaku

Science.gov (United States)

Coley, Joel B.; Corbet, R.; Mukai, K.; Pottschmidt, K.

2013-01-01

Optical and X-ray observations of 4U 1210-64 (1ES 1210-646) suggest that the source is a High Mass X-ray Binary (HMXB) probably powered by the Be mechanism. Data acquired by the RXTE All Sky Monitor (ASM), the ISS Monitor of All-sky X-ray Image (MAXI) and Suzaku provide a detailed temporal and spectral description of this poorly understood source. Long-term data produced by ASM and MAXI indicate that the source shows two distinct high and low states. A 6.7-day orbital period of the system was found in folded light curves produced by both ASM and MAXI. A two day Suzaku observation in Dec. 2010 took place during a transition from the minimum to the maximum of the folded light curve. The two day Suzaku observation reveals large variations in flux indicative of strong orbit to orbit variability. Flares in the Suzaku light curve can reach nearly 1.4 times the mean count rate. From a spectral analysis of the Suzaku data, emission lines in the Fe K alpha region were detected at 6.4 keV, 6.7 keV and 6.97 keV interpreted as FeI, FeXXV and FeXXVI. In addition, emission lines were observed at approximately 1.0 and 2.6 keV, corresponding to NeX and SXVI respectively. Thermal bremsstrahlung or power law models both modified by interstellar and partially covering absorption provide a good fit to the continuum data. This source is intriguing for these reasons: i) No pulse period was observed; ii) 6.7 day orbital period is much less than typical orbital periods seen in Be/X-ray Binaries; iii) The optical companion is a B5V--an unusual spectral class for an HMXB; iv) There are extended high and low X-ray states.

X-ray heating and the optical light curve of HZ Herculis

International Nuclear Information System (INIS)

Perrenod, S.C.; Shields, G.A.

1975-01-01

We discuss theoretically the optical light curve of HZ Her, the binary companion of the pulsed X-ray source Her X-1. Using model stellar atmospheres, we construct light curves that are in agreement with UBV photometry of HZ Her except for the sharpness of the minimum. Unlike previous authors, we find that heating of the photosphere of HZ Her by the observed X-ray flux is sufficient to explain the amplitude of the light variations in each color, if the X-ray emission persists at HZ Her throughout the 35-day ON-OFF CYCLE. We rule out a corona surrounding HZ Her as the source of the extra light near minimum, and we also rule out a model wherein the extra light is caused by a stellar wind that electron-scatters optical light emitted by the photosphere of the hot side of the star

O Star Wind Mass-Loss Rates and Shock Physics from X-ray Line Profiles in Archival XMM RGS Data

Science.gov (United States)

Cohen, David

O stars are characterized by their dense, supersonic stellar winds. These winds are the site of X-ray emission from shock-heated plasma. By analyzing high-resolution X-ray spectra of these O stars, we can learn about the wind-shock heating and X-ray production mechanism. But in addition, the X-rays can also be used to measure the mass-loss rate of the stellar wind, which is a key observational quantity whose value affects stellar evolution and energy, momentum, and mass input to the Galactic interstellar medium. We make this X-ray based mass-loss measurement by analyzing the profile shapes of the X-ray emission lines observed at high resolution with the Chandra and XMM-Newton grating spectrometers. One advantage of our method is that it is insensitive to small-scale clumping that affects density-squared diagnostics. We are applying this analysis technique to O stars in the Chandra archive, and are finding mass-loss rates lower than those traditionally assumed for these O stars, and in line with more recent independent determinations that do account for clumping. By extending this analysis to the XMM RGS data archive, we will make significant contributions to the understanding of both X-ray production in O stars and to addressing the issue of the actual mass-loss rates of O stars. The XMM RGS data archive provides several extensions and advantages over the smaller Chandra HETGS archive: (1) there are roughly twice as many O and early B stars in the XMM archive; (2) the longer wavelength response of the RGS provides access to diagnostically important lines of nitrogen and carbon; (3) the very long, multiple exposures of zeta Pup provide the opportunity to study this canonical O supergiant's X-ray spectrum in unprecedented detail, including looking at the time variability of X-ray line profiles. Our research team has developed a sophisticated empirical line profile model as well as a computational infrastructure for fitting the model to high-resolution X-ray spectra

An Optical and Infrared Time-domain Study of the Supergiant Fast X-Ray Transient Candidate IC 10 X-2

Science.gov (United States)

Kwan, Stephanie; Lau, Ryan M.; Jencson, Jacob; Kasliwal, Mansi M.; Boyer, Martha L.; Ofek, Eran; Masci, Frank; Laher, Russ

2018-03-01

We present an optical and infrared (IR) study of IC 10 X-2, a high-mass X-ray binary in the galaxy IC 10. Previous optical and X-ray studies suggest that X-2 is a Supergiant Fast X-ray Transient: a large-amplitude (factor of ∼100), short-duration (hours to weeks) X-ray outburst on 2010 May 21. We analyze R- and g-band light curves of X-2 from the intermediate Palomar Transient Factory taken between 2013 July 15 and 2017 February 14 that show high-amplitude (≳1 mag), short-duration (≲8 days) flares and dips (≳0.5 mag). Near-IR spectroscopy of X-2 from Palomar/TripleSpec show He I, Paschen-γ, and Paschen-β emission lines with similar shapes and amplitudes as those of luminous blue variables (LBVs) and LBV candidates (LBVc). Mid-IR colors and magnitudes from Spitzer/Infrared Array Camera photometry of X-2 resemble those of known LBV/LBVcs. We suggest that the stellar companion in X-2 is an LBV/LBVc and discuss possible origins of the optical flares. Dips in the optical light curve are indicative of eclipses from optically thick clumps formed in the winds of the stellar counterpart. Given the constraints on the flare duration (0.02–0.8 days) and the time between flares (15.1 ± 7.8 days), we estimate the clump volume filling factor in the stellar winds, f V , to be 0.01interpret the origin of the optical flares as the accretion of clumps formed in the winds of an LBV/LBVc onto the compact object.

THE UNUSUAL X-RAY BINARIES OF THE GLOBULAR CLUSTER NGC 6652

International Nuclear Information System (INIS)

Coomber, G.; Heinke, C. O.; Cohn, H. N.; Lugger, P. M.; Grindlay, J. E.

2011-01-01

Our 5 ks Chandra ACIS-S observation of the globular cluster NGC 6652 detected seven X-ray sources, three of which were previously unidentified. This cluster hosts a well-known bright low-mass X-ray binary, source A (or XB 1832-330). Source B shows unusual rapid flaring variability, with an average L X (0.5-10 keV) ∼2 x 10 34 erg s -1 , but with minutes-long flares up to L X = 9 x 10 34 erg s -1 . Its spectrum can be fit by an absorbed power law of photon index Γ ∼ 1.24 and hardens as the count rate decreases. This suggests that part or all of the variation might be due to obscuration by the rim of a highly inclined accretion disk. Sources C and D, with L X ∼ 10 33 erg s -1 , have soft and unusual spectra. Source C requires a very soft component, with a spectrum peaking at 0.5 keV, which might be the hot polar cap of a magnetically accreting polar cataclysmic variable. Source D shows a soft spectrum (fit by a power law of photon index ∼2.3) with marginal evidence for an emission line around 1 keV; its nature is unclear. The faint new sources E, F, and G have luminosities of 1-2 x 10 32 erg s -1 , if associated with the cluster (which is likely). E and F have relatively hard spectra (consistent with power laws with photon index ∼1.5). G lacks soft photons, suggesting absorption with N H > 10 22 cm -2 .

A NuSTAR observation of the reflection spectrum of the low-mass X-ray binary 4U 1728-34

DEFF Research Database (Denmark)

Sleator, Clio C.; Tomsick, John A.; King, Ashley L.

2016-01-01

We report on a simultaneous NuSTAR and Swift observation of the neutron star low-mass X-ray binary 4U 1728-34. We identified and removed four Type I X-ray bursts during the observation in order to study the persistent emission. The continuum spectrum is hard and described well by a blackbody with...

X-Ray and Near-Infrared Spectroscopy of Dim X-Ray Point Sources Constituting the Galactic Ridge X-Ray Emission

Directory of Open Access Journals (Sweden)

Kumiko Morihana

2014-12-01

Full Text Available We present the results of X-ray and Near-Infrared observations of the Galactic Ridge X-ray Emission (GRXE. We extracted 2,002 X-ray point sources in the Chandra Bulge Field (l =0°.113, b = 1°.424 down to ~10-14.8 ergscm-2s-1 in 2-8 keV band with the longest observation (900 ks of the GRXE. Based on X-ray brightness and hardness, we classied the X-ray point sources into three groups: A (hard, B (soft and broad spectrum, and C (soft and peaked spectrum. In order to know populations of the X-ray point sources, we carried out NIR imaging and spectroscopy observation. We identied 11% of X-ray point sources with NIR and extracted NIR spectra for some of them. Based on X-ray and NIR properties, we concluded that non-thermal sources in the group A are mostly active galactic nuclei and the thermal sources are mostly white dwarf binaries such as cataclysmic variables (CVs and Pre-CVs. We concluded that the group B and C sources are X-ray active stars in flare and quiescence, respectively.

X ray spectra of X Per. [oso-8 observations

Science.gov (United States)

Becker, R. H.; Boldt, E. A.; Holt, S. S.; Pravdo, S. H.; Robinson-Saba, J.; Serlemitsos, P. J.; Swank, J. H.

1978-01-01

The cosmic X-ray spectroscopy experiment on OSO-8 observed X Per for twenty days during two observations in Feb. 1976 and Feb. 1977. The spectrum of X Per varies in phase with its 13.9 min period, hardening significantly at X-ray minimum. Unlike other X-ray binary pulsar spectra, X Per's spectra do not exhibit iron line emission or strong absorption features. The data show no evidence for a 22 hour periodicity in the X-ray intensity of X Per. These results indicate that the X-ray emission from X Per may be originating from a neutron star in a low density region far from the optically identified Be star.

NEW X-RAY DETECTIONS OF WNL STARS

International Nuclear Information System (INIS)

Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel; Schmutz, Werner; Sokal, Kimberly R.

2012-01-01

Previous studies have demonstrated that putatively single nitrogen-type Wolf-Rayet stars (WN stars) without known companions are X-ray sources. However, almost all WN star X-ray detections so far have been of earlier WN2-WN6 spectral subtypes. Later WN7-WN9 subtypes (also known as WNL stars) have proved more difficult to detect, an important exception being WR 79a (WN9ha). We present here new X-ray detections of the WNL stars WR 16 (WN8h) and WR 78 (WN7h). These new results, when combined with previous detections, demonstrate that X-ray emission is present in WN stars across the full range of spectral types, including later WNL stars. The two WN8 stars observed to date (WR 16 and WR 40) show unusually low X-ray luminosities (L x ) compared to other WN stars, and it is noteworthy that they also have the lowest terminal wind speeds (v ∞ ). Existing X-ray detections of about a dozen WN stars reveal a trend of increasing L x with wind luminosity L wind = (1/2)M-dot v 2 ∞ , suggesting that wind kinetic energy may play a key role in establishing X-ray luminosity levels in WN stars.

NEW X-RAY DETECTIONS OF WNL STARS

Energy Technology Data Exchange (ETDEWEB)

Skinner, Stephen L. [Center for Astrophysics and Space Astronomy (CASA), University of Colorado, Boulder, CO 80309-0389 (United States); Zhekov, Svetozar A. [Space and Solar-Terrestrial Research Institute, Moskovska str. 6, Sofia-1000 (Bulgaria); Guedel, Manuel [Department of Astronomy, University of Vienna, Tuerkenschanzstr. 17, A-1180 Vienna (Austria); Schmutz, Werner [Physikalisch-Meteorologisches Observatorium Davos (PMOD), Dorfstrasse 33, CH-7260 Davos Dorf (Switzerland); Sokal, Kimberly R., E-mail: Stephen.Skinner@colorado.edu [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)

2012-05-15

Previous studies have demonstrated that putatively single nitrogen-type Wolf-Rayet stars (WN stars) without known companions are X-ray sources. However, almost all WN star X-ray detections so far have been of earlier WN2-WN6 spectral subtypes. Later WN7-WN9 subtypes (also known as WNL stars) have proved more difficult to detect, an important exception being WR 79a (WN9ha). We present here new X-ray detections of the WNL stars WR 16 (WN8h) and WR 78 (WN7h). These new results, when combined with previous detections, demonstrate that X-ray emission is present in WN stars across the full range of spectral types, including later WNL stars. The two WN8 stars observed to date (WR 16 and WR 40) show unusually low X-ray luminosities (L{sub x} ) compared to other WN stars, and it is noteworthy that they also have the lowest terminal wind speeds (v{sub {infinity}}). Existing X-ray detections of about a dozen WN stars reveal a trend of increasing L{sub x} with wind luminosity L{sub wind} = (1/2)M-dot v{sup 2}{sub {infinity}}, suggesting that wind kinetic energy may play a key role in establishing X-ray luminosity levels in WN stars.

The high-energy X-ray spectrum of Centaurus XR-3 observed from OSO 8

Science.gov (United States)

Dolan, J. F.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Orwig, L. E.

1984-01-01

Observations of the X-ray binary Cen XR-3 in the 20-120 keV energy range by means of OSO 8's high energy X-ray spectrometer, during July 16-19, 1975, and July 5-14 and 28-29, 1978, indicate that the source was in a high luminosity state during 1975 and a low luminosity one in 1978. While mean orbital light curves appear similar in shape in both years, orbit-to-orbit intensity variations are noted. Spectral, luminosity, and the 4.84 sec modulation are characterized. Cen XR-3 may be a system in which mass transfer by Roche lobe overflow, and by accretion from a stellar wind, are both effective in the production of observable X-ray radiation.

NuSTAR Hard X-Ray Survey of the Galactic Center Region. II. X-Ray Point Sources

DEFF Research Database (Denmark)

Hong, JaeSub; Mori, Kaya; Hailey, Charles J.

2016-01-01

persistent luminous X-ray binaries (XBs) and the likely run-away pulsar called the Cannonball. New source-detection significance maps reveal a cluster of hard (>10 keV) X-ray sources near the Sgr. A diffuse complex with no clear soft X-ray counterparts. The severe extinction observed in the Chandra spectra...

X-ray Emission from the Guitar Nebula

OpenAIRE

Romani, Roger W.; Cordes, James M.; Yadigaroglu, I. -A.

1997-01-01

We have detected weak soft X-ray emission from the Pulsar Wind Nebula trailing the high velocity star PSR 2224+65 (the `Guitar Nebula'). This X-ray flux gives evidence of \\gamma~10^7 eV particles in the pulsar wind and constrains the properties of the post-shock flow. The X-ray emission is most easily understood if the shocked pulsar wind is partly confined in the nebula and if magnetic fields in this zone can grow to near equipartition values.

X-Ray Emission from the Guitar Nebula

Science.gov (United States)

Romani, Roger W.; Cordes, James M.; Yadigaroglu, I.-A.

1997-01-01

We have detected weak soft X-ray emission from the pulsar wind nebula trailing the high-velocity star PSR 2224+65 (the "Guitar Nebula"). This X-ray flux gives evidence of gamma approximately 10(exp 7) eV particles in the pulsar wind and constrains the properties of the postshock flow. The X-ray emission is most easily understood if the shocked pulsar wind is partly confined in the nebula and if magnetic fields in this zone can grow to near-equipartition values.

Wind-embedded shocks in FASTWIND: X-ray emission and K-shell absorption

Science.gov (United States)

Carneiro, L. P.; Puls, J.; Sundqvist, J. O.; Hoffmann, T. L.

2017-11-01

EUV and X-ray radiation emitted from wind-embedded shocks can affect the ionization balance in the outer atmospheres of massive stars, and can also be the mechanism responsible for producing highly ionized atoms detected in the wind UV spectra. To investigate these processes, we implemented the emission from wind-embedded shocks and related physics into our atmosphere/spectrum synthesis code FASTWIND. We also account for the high energy absorption of the cool wind, by adding important K-shell opacities. Various tests justfying our approach have been described by Carneiro+(2016, A&A 590, A88). In particular, we studied the impact of X-ray emission on the ionization balance of important elements. In almost all the cases, the lower ionization stages (O iv, N iv, P v) are depleted and the higher stages (N v, O v, O vi) become enhanced. Moreover, also He lines (in particular He ii 1640 and He ii 4686) can be affected as well. Finally, we carried out an extensive discussion of the high-energy mass absorption coefficient, κν, regarding its spatial variation and dependence on T eff. We found that (i) the approximation of a radially constant κν can be justified for r >= 1.2R * and λ <= 18 Å, and also for many models at longer wavelengths. (ii) In order to estimate the actual value of this quantity, however, the He ii background needs to be considered from detailed modeling.

Exploring subluminous X-ray binaries

NARCIS (Netherlands)

Degenaar, N.D.

2010-01-01

Halfway the twentieth century, technological developments made it possible to carry detection instruments outside the absorbing layers of the Earth’s atmosphere onboard rockets and satellites. This opened up the opportunity to detect the emission from celestial objects at X-ray wavelengths, thereby

On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange

Science.gov (United States)

Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.;

X-rays as a probe of the Universe

Indian Academy of Sciences (India)

Table of contents. X-rays as a probe of the Universe · Probing the Universe ….. Flux = sT4 umax = 1011 T (in Kelvin) · History of x-ray astronomy · X-ray Production · X-ray spectra · Celestial sphere as seen by UHURU (1970) · Slide 8 · X-rays from accreting binary systems · Slide 10 · Neutron stars: Black Hole: · Primary X-ray ...

INTEGRAL finds renewed X-ray activity of the Neutron star X-ray transient SAX J1750.8-2900

DEFF Research Database (Denmark)

Sanchez-Fernandez, Celia; Chenevez, Jérôme; Kuulkers, Erik

2015-01-01

INTEGRAL Galactic bulge monitoring observations (ATel #438) on UT 13 September 2015 18:50-22:32 reveal renewed X-ray activity from the low-mass X-ray binary transient and Type I X-ray burster SAX J1750.8-2900 (IAU Circ. #6597). The last outburst from this source was reported in 2011 (ATels #3170,...

A First Estimate of the X-Ray Binary Frequency as a Function of Star Cluster Mass in a Single Galactic System

Science.gov (United States)

Clark, D. M.; Eikenberry, S. S.; Brandl, B. R.; Wilson, J. C.; Carson, J. C.; Henderson, C. P.; Hayward, T. L.; Barry, D. J.; Ptak, A. F.; Colbert, E. J. M.

2008-05-01

We use the previously identified 15 infrared star cluster counterparts to X-ray point sources in the interacting galaxies NGC 4038/4039 (the Antennae) to study the relationship between total cluster mass and X-ray binary number. This significant population of X-Ray/IR associations allows us to perform, for the first time, a statistical study of X-ray point sources and their environments. We define a quantity, η, relating the fraction of X-ray sources per unit mass as a function of cluster mass in the Antennae. We compute cluster mass by fitting spectral evolutionary models to Ks luminosity. Considering that this method depends on cluster age, we use four different age distributions to explore the effects of cluster age on the value of η and find it varies by less than a factor of 4. We find a mean value of η for these different distributions of η = 1.7 × 10-8 M-1⊙ with ση = 1.2 × 10-8 M-1⊙. Performing a χ2 test, we demonstrate η could exhibit a positive slope, but that it depends on the assumed distribution in cluster ages. While the estimated uncertainties in η are factors of a few, we believe this is the first estimate made of this quantity to "order of magnitude" accuracy. We also compare our findings to theoretical models of open and globular cluster evolution, incorporating the X-ray binary fraction per cluster.

Light Curve and SED Modeling of the Gamma-Ray Binary 1FGL J1018.6–5856: Constraints on the Orbital Geometry and Relativistic Flow

Energy Technology Data Exchange (ETDEWEB)

An, Hongjun; Romani, Roger W., E-mail: hjan@chungbuk.ac.kr [Department of Physics/KIPAC, Stanford University, Stanford, CA 94305-4060 (United States)

2017-04-01

We present broadband spectral energy distributions and light curves of the gamma-ray binary 1FGL J1018.6−5856 measured in the X-ray and the gamma-ray bands. We find that the orbital modulation in the low-energy gamma-ray band is similar to that in the X-ray band, suggesting a common spectral component. However, above a GeV the orbital light curve changes significantly. We suggest that the GeV band contains significant flux from a pulsar magnetosphere, while the X-ray to TeV light curves are dominated by synchrotron and Compton emission from an intrabinary shock (IBS). We find that a simple one-zone model is inadequate to explain the IBS emission, but that beamed Synchrotron-self Compton radiation from adiabatically accelerated plasma in the shocked pulsar wind can reproduce the complex multiband light curves, including the variable X-ray spike coincident with the gamma-ray maximum. The model requires an inclination of ∼50° and an orbital eccentricity of ∼0.35, consistent with the limited constraints from existing optical observations. This picture motivates searches for pulsations from the energetic young pulsar powering the wind shock.

Chandra Observations of the Eclipsing Wolf-Rayet Binary CQ CepOver a Full Orbital Cycle

Science.gov (United States)

Skinner, Steve L.; Guedel, Manuel; Schmutz, Werner; Zhekov, Svetozar

2018-06-01

We present results of Chandra X-ray observations and simultaneous optical light curves of the short-period (1.64 d) eclipsing WN6+O9 binary system CQ Cep obtained in 2013 and 2017 covering a full binary orbit. Our primary objective was to compare the observed X-ray properties with colliding wind shock theory, which predicts that the hottest shock plasma (T > 20 MK) will form on or near the line-of-centers between the stars. Thus, X-ray variability is expected during eclipses when the hottest plasma is occulted. The X-ray spectrum is strikingly similar to apparently single WN6 stars such as WR 134 and spectral lines reveal plasma over a broad range of temperatures T ~ 4 - 40 MK. Both primary and secondary optical eclipses were clearly detected and provide an accurate orbital period determination (P = 1.6412 d). The X-ray emission remained remarkably steady throughout the orbit and statistical tests give a low probability of variability. The lack of significant X-ray variabililty during eclipses indicates that the X-ray emission is not confined along the line-of-centers but is extended on larger spatial scales, contrary to colliding wind predictions.

Handbook of X-Ray Astronomy

Science.gov (United States)

Arnaud, Keith A. (Editor); Smith, Randall K.; Siemiginowska, Aneta

2011-01-01

X-ray astronomy was born in the aftermath of World War II as military rockets were repurposed to lift radiation detectors above the atmosphere for a few minutes at a time. These early flights detected and studied X-ray emission from the Solar corona. The first sources beyond the Solar System were detected during a rocket flight in 1962 by a team headed by Riccardo Giaccom at American Science and Engineering, a company founded by physicists from MIT. The rocket used Geiger counters with a system designed to reduce non-X-ray backgrounds and collimators limiting the region of sky seen by the counters. As the rocket spun, the field of view (FOV) happened to pass over what was later found to be the brightest non-Solar X-ray source; later designated See X-1. It also detected a uniform background glow which could not be resolved into individual sources. A follow-up campaign using X-ray detectors with better spatial resolution and optical telescopes identified See X-1 as an interacting binary with a compact (neutron star) primary. This success led to further suborbital rocket flights by a number of groups. More X-ray binaries were discovered, as well as X-ray emission from supernova remnants, the radio galaxies M87 and Cygnus-A, and the Coma cluster. Detectors were improved and Geiger counters were replaced by proportional counters, which provided information about energy spectra of the sources. A constant challenge was determining precise positions of sources as only collimators were available.

X-ray astronomy

International Nuclear Information System (INIS)

Giacconi, R.; Setti, G.

1980-01-01

This book contains the lectures, and the most important seminars held at the NATO meeting on X-Ray astronomy in Erice, July 1979. The meeting was an opportune forum to discuss the results of the first 8-months of operation of the X-ray satellite, HEAO-2 (Einstein Observatory) which was launched at the end of 1978. Besides surveying these results, the meeting covered extragalactic astronomy, including the relevant observations obtained in other portions of the electromagnetic spectrum (ultra-violet, optical, infrared and radio). The discussion on galactic X-ray sources essentially covered classical binaries, globular clusters and bursters and its significance to extragalactic sources and to high energy astrophysics was borne in mind. (orig.)

Numerical Simulations of Wind Accretion in Symbiotic Binaries

Science.gov (United States)

de Val-Borro, M.; Karovska, M.; Sasselov, D.

2009-08-01

About half of the binary systems are close enough to each other for mass to be exchanged between them at some point in their evolution, yet the accretion mechanism in wind accreting binaries is not well understood. We study the dynamical effects of gravitational focusing by a binary companion on winds from late-type stars. In particular, we investigate the mass transfer and formation of accretion disks around the secondary in detached systems consisting of an asymptotic giant branch (AGB) mass-losing star and an accreting companion. The presence of mass outflows is studied as a function of mass-loss rate, wind temperature, and binary orbital parameters. A two-dimensional hydrodynamical model is used to study the stability of mass transfer in wind accreting symbiotic binary systems. In our simulations we use an adiabatic equation of state and a modified version of the isothermal approximation, where the temperature depends on the distance from the mass losing star and its companion. The code uses a block-structured adaptive mesh refinement method that allows us to have high resolution at the position of the secondary and resolve the formation of bow shocks and accretion disks. We explore the accretion flow between the components and formation of accretion disks for a range of orbital separations and wind parameters. Our results show the formation of stream flow between the stars and accretion disks of various sizes for certain orbital configurations. For a typical slow and massive wind from an AGB star the flow pattern is similar to a Roche lobe overflow with accretion rates of 10% of the mass loss from the primary. Stable disks with exponentially decreasing density profiles and masses of the order 10-4 solar masses are formed when wind acceleration occurs at several stellar radii. The disks are geometrically thin with eccentric streamlines and close to Keplerian velocity profiles. The formation of tidal streams and accretion disks is found to be weakly dependent on

NUMERICAL SIMULATIONS OF WIND ACCRETION IN SYMBIOTIC BINARIES

International Nuclear Information System (INIS)

De Val-Borro, M.; Karovska, M.; Sasselov, D.

2009-01-01

About half of the binary systems are close enough to each other for mass to be exchanged between them at some point in their evolution, yet the accretion mechanism in wind accreting binaries is not well understood. We study the dynamical effects of gravitational focusing by a binary companion on winds from late-type stars. In particular, we investigate the mass transfer and formation of accretion disks around the secondary in detached systems consisting of an asymptotic giant branch (AGB) mass-losing star and an accreting companion. The presence of mass outflows is studied as a function of mass-loss rate, wind temperature, and binary orbital parameters. A two-dimensional hydrodynamical model is used to study the stability of mass transfer in wind accreting symbiotic binary systems. In our simulations we use an adiabatic equation of state and a modified version of the isothermal approximation, where the temperature depends on the distance from the mass losing star and its companion. The code uses a block-structured adaptive mesh refinement method that allows us to have high resolution at the position of the secondary and resolve the formation of bow shocks and accretion disks. We explore the accretion flow between the components and formation of accretion disks for a range of orbital separations and wind parameters. Our results show the formation of stream flow between the stars and accretion disks of various sizes for certain orbital configurations. For a typical slow and massive wind from an AGB star the flow pattern is similar to a Roche lobe overflow with accretion rates of 10% of the mass loss from the primary. Stable disks with exponentially decreasing density profiles and masses of the order 10 -4 solar masses are formed when wind acceleration occurs at several stellar radii. The disks are geometrically thin with eccentric streamlines and close to Keplerian velocity profiles. The formation of tidal streams and accretion disks is found to be weakly dependent

Phase lags of quasi-periodic oscillations across source states in the low-mass X-ray binary 4U 1636-53

Science.gov (United States)

de Avellar, Marcio G. B.

2017-06-01

The majority of attempts to explain the origin and phenomenology of the quasi-periodic oscillations (QPOs) detected in low-mass X-ray binaries invoke dynamical models, and it was just in recent years that renewed attention has been given on how radiative processes occurring in these extreme environments gives rise to the variability features observed in the X-ray light curves of these systems. The study of the dependence of the phase lags upon the energy and frequency of the QPOs is a step towards this end. The methodology we developed here allowed us to study for the first time these dependencies for all QPOs detected in the range of 1 to 1300 Hz in the low-mass X-ray binary 4U 1636-53 as the source changes its state during its cycle in the colour-colour diagram. Our results suggest that within the context of models of up-scattering Comptonization, the phase lags dependencies upon frequency and energy can be used to extract size scales and physical conditions of the medium that produces the lags.

Astrophysical parameters and orbital solution of the peculiar X-ray transient IGR J00370+6122

Science.gov (United States)

González-Galán, A.; Negueruela, I.; Castro, N.; Simón-Díaz, S.; Lorenzo, J.; Vilardell, F.

2014-06-01

Context. BD + 60° 73 is the optical counterpart of the X-ray source IGR J00370+6122, a probable accretion-powered X-ray pulsar. The X-ray light curve of this binary system shows clear periodicity at 15.7 d, which has been interpreted as repeated outbursts around the periastron of an eccentric orbit. Aims: We aim to characterise the binary system IGR J00370+6122 by deriving its orbital and physical parameters. Methods: We obtained high-resolution spectra of BD + 60° 73 at different epochs. We used the fastwind code to generate a stellar atmosphere model to fit the observed spectrum and obtain physical magnitudes. The synthetic spectrum was used as a template for cross-correlation with the observed spectra to measure radial velocities. The radial velocity curve provided an orbital solution for the system. We also analysed the RXTE/ASM and Swift/BAT light curves to confirm the stability of the periodicity. Results: BD + 60° 73 is a BN0.7 Ib low-luminosity supergiant located at a distance ~3.1 kpc, in the Cas OB4 association. We derive Teff = 24 000 K and log gc = 3.0, and chemical abundances consistent with a moderately high level of evolution. The spectroscopic and evolutionary masses are consistent at the 1-σ level with a mass M∗ ≈ 15 M⊙. The recurrence time of the X-ray flares is the orbital period of the system. The neutron star is in a high-eccentricity (e = 0.56 ± 0.07) orbit, and the X-ray emission is strongly peaked around orbital phase φ = 0.2, though the observations are consistent with some level of X-ray activity happening at all orbital phases. Conclusions: The X-ray behaviour of IGR J00370+6122 is reminiscent of "intermediate" supergiant X-ray transients, though its peak luminosity is rather low. The orbit is somewhat wider than those of classical persistent supergiant X-ray binaries, which when combined with the low luminosity of the mass donor, explains the low X-ray luminosity. IGR J00370+6122 will very likely evolve towards a persistent

NuSTAR OBSERVATIONS AND BROADBAND SPECTRAL ENERGY DISTRIBUTION MODELING OF THE MILLISECOND PULSAR BINARY PSR J1023+0038

Energy Technology Data Exchange (ETDEWEB)

Li, K. L.; Kong, A. K. H.; Tam, P. H. T.; Jin, Ruolan [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Takata, J.; Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Hui, C. Y., E-mail: lilirayhk@gmail.com, E-mail: akong@phys.nthu.edu.tw, E-mail: takata@hku.hk [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

2014-12-20

We report the first hard X-ray (3-79 keV) observations of the millisecond pulsar (MSP) binary PSR J1023+0038 using NuSTAR. This system has been shown transiting between a low-mass X-ray binary (LMXB) state and a rotation-powered MSP state. The NuSTAR observations were taken in both LMXB state and rotation-powered state. The source is clearly seen in both states up to ∼79 keV. During the LMXB state, the 3-79 keV flux is about a factor of 10 higher than in the rotation-powered state. The hard X-rays show clear orbital modulation during the X-ray faint rotation-powered state but the X-ray orbital period is not detected in the X-ray bright LMXB state. In addition, the X-ray spectrum changes from a flat power-law spectrum during the rotation-powered state to a steeper power-law spectrum in the LMXB state. We suggest that the hard X-rays are due to the intrabinary shock from the interaction between the pulsar wind and the injected material from the low-mass companion star. During the rotation-powered MSP state, the X-ray orbital modulation is due to Doppler boosting of the shocked pulsar wind. At the LMXB state, the evaporating matter of the accretion disk due to the gamma-ray irradiation from the pulsar stops almost all the pulsar wind, resulting in the disappearance of the X-ray orbital modulation.

JEM-X observations of the Be/X-ray binary EXO 2030+375

DEFF Research Database (Denmark)

Nunez, S.M.; Reig, P.; Blay, P.

2003-01-01

We have used data from the Joint European Monitor (JEM-X) to perform an X-ray spectral and timing analysis of the 42-s transient pulsar EXO 2030+375 during an X-ray outburst. X-ray pulsations are clearly detected with an average pulse period of 41.66+/-0.05 s and an average pulse fraction of 60...

Laboratory measurements of 50-300 eV X rays from collisions of cometary interest: Ne and S L X rays, Fe M X rays and others

International Nuclear Information System (INIS)

Verzani, C.J.; Miller, K.; Wrigley, A.; Kessel, Q.; Smith, W.W.; Smith, S.J.; Hossain, S.; Chutjian, A.

2007-01-01

Laboratory measurements simulating the impact of certain solar wind ions on CO have been made. Preliminary analysis of the X rays in the 50-300 eV energy range produced by these collisions suggests that a dominant role is played by electron capture and subsequent relaxation of the electron to the n = 2 levels of solar wind ions such as Ne and S. In particular our data show that X rays from Ne play a role that is at least as significant as that of the more dominant solar wind ion O 6+ in this X-ray energy range. It may be assumed that Mg and Si may also play an important role; however, these ions were not included in the present experiment

New Worlds / New Horizons Science with an X-ray Astrophysics Probe

Science.gov (United States)

Smith, Randall K.; Bookbinder, Jay A.; Hornschemeier, Ann E.; Bandler, Simon; Brandt, W. N.; Hughes, John P.; McCammon, Dan; Matsumoto, Hironori; Mushotzky, Richard; Osten, Rachel A.;

X-ray observation of the shocked red supergiant wind of Cassiopeia A

International Nuclear Information System (INIS)

Lee, Jae-Joon; Park, Sangwook; Hughes, John P.; Slane, Patrick O.

2014-01-01

Cas A is a Galactic supernova remnant whose supernova explosion is observed to be of Type IIb from spectroscopy of its light echo. Having its SN type known, observational constraints on the mass-loss history of Cas A's progenitor can provide crucial information on the final fate of massive stars. In this paper, we study X-ray characteristics of the shocked ambient gas in Cas A using the 1 Ms observation carried out with the Chandra X-Ray Observatory and try to constrain the mass-loss history of the progenitor star. We identify thermal emission from the shocked ambient gas along the outer boundary of the remnant. Comparison of measured radial variations of spectroscopic parameters of the shocked ambient gas to the self-similar solutions of Chevalier show that Cas A is expanding into a circumstellar wind rather than into a uniform medium. We estimate a wind density n H ∼ 0.9 ± 0.3 cm –3 at the current outer radius of the remnant (∼3 pc), which we interpret as a dense slow wind from a red supergiant (RSG) star. Our results suggest that the progenitor star of Cas A had an initial mass around 16 M ☉ , and its mass before the explosion was about 5 M ☉ , with uncertainties of several tens of percent. Furthermore, the results suggest that, among the mass lost from the progenitor star (∼11 M ☉ ), a significant amount (more than 6 M ☉ ) could have been via its RSG wind.

GLOBULAR CLUSTER FORMATION EFFICIENCIES FROM BLACK HOLE X-RAY BINARY FEEDBACK

Energy Technology Data Exchange (ETDEWEB)

Justham, Stephen [The Key Laboratory of Optical Astronomy, National Astronomical Observatories, The Chinese Academy of Sciences, Datun Road, Beijing 100012 (China); Peng, Eric W. [Department of Astronomy, Peking University, Beijing 100871 (China); Schawinski, Kevin, E-mail: sjustham@nao.cas.cn [Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich (Switzerland)

2015-08-10

We investigate a scenario in which feedback from black hole X-ray binaries (BHXBs) sometimes begins inside young star clusters before strong supernova (SN) feedback. Those BHXBs could reduce the gas fraction inside embedded young clusters while maintaining virial equilibrium, which may help globular clusters (GCs) to stay bound when SN-driven gas ejection subsequently occurs. Adopting a simple toy model with parameters guided by BHXB population models, we produce GC formation efficiencies consistent with empirically inferred values. The metallicity dependence of BHXB formation could naturally explain why GC formation efficiency is higher at lower metallicity. For reasonable assumptions about that metallicity dependence, our toy model can produce a GC metallicity bimodality in some galaxies without a bimodality in the field-star metallicity distribution.

Radiation parameters of the X-ray binary A 0535+26=HDE 245770 from the polarization and photometric data

International Nuclear Information System (INIS)

Larionov, V.M.

1987-01-01

An analysis of Shakhovskay et al's observations of the X-ray binary A 0535+26=HDE 245770 made it possible to distinguish in its radiation the two components connected with the visible star (O9 III) and the accretion disc around the neutron star. The interstellar polarization parameters are in accordance with Serkowski's formula and the observations of the field stars. The IR and optical variability can be explained in terms of variable accretion disc radiation. The intrinsic polarization parameters obtained can be used to predict, in the model proposed, the directions of the polarization vectors in the IR and X-ray bands

The optical polarization of X-ray binaries

International Nuclear Information System (INIS)

Dolan, J.F.

1977-01-01

Polarimetric observations of close binaries may reveal the presence of a black-hole secondary. The Einstein photometric effect will introduce a characteristic, time-varying signature upon the interstellar polarization. For several reasons, it is concluded that the short time-scale variability in the polarization in HDE 226868 is caused by Rayleigh scattering from gas streams known to exist in the system. X Persei may have a variable polarization consistent with the predicted effectics and (Auth)

A likely candidate of type Ia supernova progenitors: the X-ray pulsating companion of the hot subdwarf HD 49798

International Nuclear Information System (INIS)

Wang Bo; Han Zhanwen

2010-01-01

HD 49798 is a hydrogen depleted subdwarf O6 star and has an X-ray pulsating companion (RX J0648.0-4418). The X-ray pulsating companion is a massive white dwarf. Employing Eggleton's stellar evolution code with the optically thick wind assumption, we find that the hot subdwarf HD 49798 and its X-ray pulsating companion could produce a type Ia supernova (SN Ia) in future evolution. This implies that the binary system is a likely candidate of an SN Ia progenitor. We also discuss the possibilities of some other WD + He star systems (e.g. V445 Pup and KPD 1930+2752) for producing SNe Ia. (research papers)

Gemini/GNIRS infrared spectroscopy of the Wolf-Rayet stellar wind in Cygnus X-3

Science.gov (United States)

Koljonen, K. I. I.; Maccarone, T. J.

2017-12-01

The microquasar Cygnus X-3 was observed several times with the Gemini North Infrared Spectrograph while the source was in the hard X-ray state. We describe the observed 1.0-2.4 μm spectra as arising from the stellar wind of the companion star and suggest its classification as a WN 4-6 Wolf-Rayet star. We attribute the orbital variations of the emission line profiles to the variations in the ionization structure of the stellar wind caused by the intense X-ray emission from the compact object. The strong variability observed in the line profiles will affect the mass function determination. We are unable to reproduce earlier results, from which the mass function for the Wolf-Rayet star was derived. Instead, we suggest that the system parameters are difficult to obtain from the infrared spectra. We find that the near-infrared continuum and the line spectra can be represented with non-LTE Wolf-Rayet atmosphere models if taking into account the effects arising from the peculiar ionization structure of the stellar wind in an approximative manner. From the representative models we infer the properties of the Wolf-Rayet star and discuss possible mass ranges for the binary components.

AN EXTENDED AND MORE SENSITIVE SEARCH FOR PERIODICITIES IN ROSSI X-RAY TIMING EXPLORER/ALL-SKY MONITOR X-RAY LIGHT CURVES

International Nuclear Information System (INIS)

Levine, Alan M.; Bradt, Hale V.; Chakrabarty, Deepto; Corbet, Robin H. D.; Harris, Robert J.

2011-01-01

We present the results of a systematic search in ∼14 years of Rossi X-ray Timing Explorer All-Sky Monitor (ASM) data for evidence of periodicities. Two variations of the commonly used Fourier analysis search method have been employed to significantly improve upon the sensitivity achieved by Wen et al. in 2006, who also searched for periodicities in ASM data. In addition, the present search is comprehensive in terms of sources studied and frequency range covered, and has yielded the detection of the signatures of the orbital periods of eight low-mass X-ray binary systems and of ten high-mass X-ray binaries not listed in the tables of Wen et al. Orbital periods, epochs, signal amplitudes, modulation fractions, and folded light curves are given for each of these systems. Seven of the orbital periods are the most precise reported to date. In the course of this work, the 18.545 day orbital period of IGR J18483-0311 was co-discovered, and the first detections in X-rays were made of the ∼3.9 day orbital period of LMC X-1 and the ∼3.79 hr orbital period of 4U 1636-536. The results inform future searches for orbital and other periodicities in X-ray binaries.

X-ray and extreme ultraviolet emission from comets

Science.gov (United States)

Lisse, C. M.; Cravens, T. E.; Dennerl, K.

The discovery of high energy X-ray emission in 1996 from C/1996 B2 (Hyakutake) has created a surprising new class of X-ray emitting objects. The original discovery (Lisse et al., 1996) and subsequent detection of X-rays from 17 other comets (Table 1) have shown that the very soft (E < 1 keV) emission is due to an interaction between the solar wind and the comet's atmosphere, and that X-ray emission is a fundamental property of comets. Theoretical and observational work has demonstrated that charge exchange collisions of highly charged solar wind ions with cometary neutral species is the best explanation for the emission. Now a rapidly changing and expanding field, the study of cometary X-ray emission appears to be able to lead us to a better understanding of a number of physical phenomena: the nature of the cometary coma, other sources of X-ray emission in the solar system, the structure of the solar wind in the heliosphere, and the source of the local soft X-ray background.

Phase lags of quasi-periodic oscillations across source states in the low-mass X-ray binary 4U 1636–53

International Nuclear Information System (INIS)

De Avellar, Marcio G B

2017-01-01

The majority of attempts to explain the origin and phenomenology of the quasi-periodic oscillations (QPOs) detected in low-mass X-ray binaries invoke dynamical models, and it was just in recent years that renewed attention has been given on how radiative processes occurring in these extreme environments gives rise to the variability features observed in the X-ray light curves of these systems. The study of the dependence of the phase lags upon the energy and frequency of the QPOs is a step towards this end. The methodology we developed here allowed us to study for the first time these dependencies for all QPOs detected in the range of 1 to 1300 Hz in the low-mass X-ray binary 4U 1636–53 as the source changes its state during its cycle in the colour-colour diagram. Our results suggest that within the context of models of up-scattering Comptonization, the phase lags dependencies upon frequency and energy can be used to extract size scales and physical conditions of the medium that produces the lags. (paper)

Topics in High-Energy Astrophysics: X-ray Time Lags and Gamma-ray Flares

Science.gov (United States)

Kroon, John J.

2016-03-01

The Universe is host to a wide variety of high-energy processes that convert gravitational potential energy or rest-mass energy into non-thermal radiation such as bremsstrahlung and synchrotron. Prevailing models of X-ray emission from accreting Black Hole Binaries (BHBs) struggle to simultaneously fit the quiescent X-ray spectrum and the transients which result in the phenomenon known as X-ray time lags. And similarly, classical models of diffusive shock acceleration in pulsar wind nebulae fail to explain the extreme particle acceleration in very short timescales as is inferred from recent gamma-ray flares from the Crab nebula. In this dissertation, I develop new exact analytic models to shed light on these intriguing processes. I take a fresh look at the formation of X-ray time lags in compact sources using a new mathematical approach in which I obtain the exact Green's function solution. The resulting Green's function allows one to explore a variety of injection scenarios, including both monochromatic and broadband (bremsstrahlung) seed photon injection. I obtain the exact solution for the dependence of the time lags on the Fourier frequency, for both homogeneous and inhomogeneous clouds. The model can successfully reproduce both the observed time lags and the quiescent X-ray spectrum using a single set of coronal parameters. I show that the implied coronal radii in the new model are significantly smaller than those obtained in the Monte Carlo simulations, hence greatly reducing the coronal heating problem. Recent bright gamma-ray flares from the Crab nebula observed by AGILE and Fermi reaching GeV energies and lasting several days challenge the contemporary model for particle acceleration in pulsar wind nebulae, specifically the diffusive shock acceleration model. Simulations indicate electron/positron pairs in the Crab nebula pulsar wind must be accelerated up to PeV energies in the presence of ambient magnetic fields with strength B ~100 microG. No

Future X-ray Polarimetry of Relativistic Accelerators: Pulsar Wind Nebulae and Supernova Remnants

Directory of Open Access Journals (Sweden)

Niccolò Bucciantini

2018-03-01

Full Text Available Supernova remnants (SNRs and pulsar wind nebulae (PWNs are among the most significant sources of non-thermal X-rays in the sky, and the best means by which relativistic plasma dynamics and particle acceleration can be investigated. Being strong synchrotron emitters, they are ideal candidates for X-ray polarimetry, and indeed the Crab nebula is up to present the only object where X-ray polarization has been detected with a high level of significance. Future polarimetric measures will likely provide us with crucial information on the level of turbulence that is expected at particle acceleration sites, together with the spatial and temporal coherence of magnetic field geometry, enabling us to set stronger constraints on our acceleration models. PWNs will also allow us to estimate the level of internal dissipation. I will briefly review the current knowledge on the polarization signatures in SNRs and PWNs, and I will illustrate what we can hope to achieve with future missions such as IXPE/XIPE.

CHANDRA X-RAY AND HUBBLE SPACE TELESCOPE IMAGING OF OPTICALLY SELECTED KILOPARSEC-SCALE BINARY ACTIVE GALACTIC NUCLEI. II. HOST GALAXY MORPHOLOGY AND AGN ACTIVITY

International Nuclear Information System (INIS)

Shangguan, Jinyi; Ho, Luis C.; Liu, Xin; Shen, Yue; Peng, Chien Y.; Greene, Jenny E.; Strauss, Michael A.

2016-01-01

Binary active galactic nuclei (AGNs) provide clues to how gas-rich mergers trigger and fuel AGNs and how supermassive black hole (SMBH) pairs evolve in a gas-rich environment. While significant effort has been invested in their identification, the detailed properties of binary AGNs and their host galaxies are still poorly constrained. In a companion paper, we examined the nature of ionizing sources in the double nuclei of four kiloparsec-scale binary AGNs with redshifts between 0.1 and 0.2. Here, we present their host galaxy morphology based on F336W ( U -band) and F105W ( Y -band) images taken by the Wide Field Camera 3 on board the Hubble Space Telescope . Our targets have double-peaked narrow emission lines and were confirmed to host binary AGNs with follow-up observations. We find that kiloparsec-scale binary AGNs occur in galaxy mergers with diverse morphological types. There are three major mergers with intermediate morphologies and a minor merger with a dominant disk component. We estimate the masses of the SMBHs from their host bulge stellar masses and obtain Eddington ratios for each AGN. Compared with a representative control sample drawn at the same redshift and stellar mass, the AGN luminosities and Eddington ratios of our binary AGNs are similar to those of single AGNs. The U − Y color maps indicate that clumpy star-forming regions could significantly affect the X-ray detection of binary AGNs, e.g., the hardness ratio. Considering the weak X-ray emission in AGNs triggered in merger systems, we suggest that samples of X-ray-selected AGNs may be biased against gas-rich mergers.

Excitation of Neutron Star f-mode in Low Mass X-ray Binaries

International Nuclear Information System (INIS)

Araujo, J C N de; Miranda, O D; Aguiar, O D

2006-01-01

Neutron Stars (NSs) present a host of pulsation modes. Only a few of them, however, is of relevance from the gravitational wave (GW) point of view. Among the various possible modes the pulsation energy is mostly stored in the f-mode in which the fluid parameters undergo the largest changes. An important question is how the pulsation modes are excited in NSs. Here we consider the excitation of the f-mode in the accreting NSs belonging to Low Mass X-ray Binaries (LMXBs), which may well be a recurrent source of GWs, since the NSs are continuously receiving matter from their companion stars. We also discuss the detectability of the GWs for the scenario considered here

Improvements in or relating to pulsed X-ray units

International Nuclear Information System (INIS)

Bichenkov, E.I.; Klypin, V.V.; Palchikov, E.I.

1983-01-01

A pulsed X-ray unit comprises a pulsed X-ray tube connected to a discharge capacitor. The discharge capacitor comprises two coaxially arranged cylinders. One cylinder of the discharge capacitor is connected to the X-ray tube and to the high-voltage end of the secondary winding of the pulsed transformer which is shaped as a truncated cone, and is arranged internally of this winding coaxially therewith. The other cylinder of the discharge capacitor is also connected to the X-ray tube and to the low-voltage end of the secondary winding of the pulsed transformer, and is arranged intermediate this winding and the primary winding of the pulsed transformer which is shaped as a hollow cylinder, and connected to the charging device. The cylinders of the discharge capacitor have ports made therein for the passage therethrough of the magnetic flux produced by the windings of the pulsed transformer. (author)

A CHANDRA PERSPECTIVE ON GALAXY-WIDE X-RAY BINARY EMISSION AND ITS CORRELATION WITH STAR FORMATION RATE AND STELLAR MASS: NEW RESULTS FROM LUMINOUS INFRARED GALAXIES

International Nuclear Information System (INIS)

Lehmer, B. D.; Jenkins, L. P.; Alexander, D. M.; Goulding, A. D.; Roberts, T. P.; Bauer, F. E.; Brandt, W. N.; Ptak, A.

2010-01-01

We present new Chandra observations that complete a sample of seventeen (17) luminous infrared galaxies (LIRGs) with D H ∼ 20 cm -2 . The LIRGs in our sample have total infrared (8-1000 μm) luminosities in the range of L IR ∼ (1-8) x 10 11 L sun . The high-resolution imaging and X-ray spectral information from our Chandra observations allow us to measure separately X-ray contributions from active galactic nuclei and normal galaxy processes (e.g., X-ray binaries and hot gas). We utilized total infrared plus UV luminosities to estimate star formation rates (SFRs) and K-band luminosities and optical colors to estimate stellar masses (M * ) for the sample. Under the assumption that the galaxy-wide 2-10 keV luminosity (L gal HX ) traces the combined emission from high-mass X-ray binaries (HMXBs) and low-mass X-ray binaries, and that the power output from these components is linearly correlated with SFR and M * , respectively, we constrain the relation L gal HX = αM * + βSFR. To achieve this, we construct a Chandra-based data set composed of our new LIRG sample combined with additional samples of less actively star-forming normal galaxies and more powerful LIRGs and ultraluminous infrared galaxies (ULIRGs) from the literature. Using these data, we measure best-fit values of α = (9.05 ± 0.37) x 10 28 erg s -1 M -1 sun and β = (1.62 ± 0.22) x 10 39 erg s -1 (M sun yr -1 ) -1 . This scaling provides a more physically meaningful estimate of L gal HX , with ∼0.1-0.2 dex less scatter, than a direct linear scaling with SFR. Our results suggest that HMXBs dominate the galaxy-wide X-ray emission for galaxies with SFR/M * ∼>5.9 x 10 -11 yr -1 , a factor of ∼2.9 times lower than previous estimates. We find that several of the most powerful LIRGs and ULIRGs, with SFR/M * ∼> 10 -9 yr -1 , appear to be X-ray underluminous with respect to our best-fit relation. We argue that these galaxies are likely to contain X-ray binaries residing in compact star-forming regions

Charge exchange laboratory studies relevant to solar-wind-induced cometary and planetary X-ray emission

Science.gov (United States)

Eissa, Farhat

The discovery of cometary X-ray emission for the first time in 1996, from comet Hyukatake using the Röntgen satellite (ROSAT) [Lisse, C. M. et al., 1996] was a highly surprising event. Since then, X-ray and extreme ultra violet (X-EUV) emission has been observed from a number of comets [Lisse, C. M. et al., 2001]. The production of such radiation is strongly believed to be the result of the charge exchange collisions of the minor heavy highly charged solar wind (SW) ions with cometary neutrals. This study reports the first state-selective He- like X-ray spectra resulting from single-electron capture (SEC) in charge exchange collisions of O 7+ and Ne 9+ with He and CO targets at a collision velocity of 800 km/s. The ions and velocity are typical of solar wind ions while the molecular and atomic targets are typical of cometary (CO) and interstellar (He) neutrals. The spectra have been obtained by means of simultaneous cold-target recoil ion momentum spectroscopic (COLTRIMS) and X-ray spectroscopic measurements that involved the triple-coincident detection of X- rays, scattered projectile, and target recoil ions. The spectra test the ability of theories to account for the relative population of triplet and singlet states in He-like product ions following SEC. The O 7+ +He spectra are compared with theoretical spectra based on quantal molecular-orbital close- coupling (QMOCC) and multi-channel Landau-Zener (MCLZ) calculations. In addition, all spectra have been used to extract angular momentum distributions based on the traditional 3:1 triplet-to-singlet ratio assumption for the populated states. The QMOCC and MCLZ calculations and the experimental results, however, suggest significant departures from this assumption. The extracted l - distributions are state-of-the-art at this time for modeling purposes due to the high differentiation power of the experimental procedure.

ROSAT Energy Spectra of Low-Mass X-Ray Binaries

Science.gov (United States)

Schulz, N. S.

1999-01-01

The 0.1-2.4 keV bandpass of the ROSAT Position Sensitive Proportional Counter (PSPC) offers an opportunity to study the very soft X-ray continuum of bright low-mass X-ray binaries (LMXBs). In 46 pointed observations, 23 LMXBs were observed with count rates between 0.4 and 165.4 counts s-1. The survey identified a total of 29 different luminosity levels, which are compared with observations and identified spectral states from other missions. The atoll source 4U 1705-44 was observed near Eddington luminosities in an unusually high intensity state. Spectral analysis provided a measure of the interstellar column density for all 49 observations. The sensitivity of spectral fits depends strongly on column density. Fits to highly absorbed spectra are merely insensitive toward any particular spectral model. Sources with column densities well below 1022 cm-2 are best fitted by power laws, while the blackbody model gives clearly worse fits to the data. Most single-component fits from sources with low column densities, however, are not acceptable at all. The inclusion of a blackbody component in eight sources can improve the fits significantly. The obtained emission radii of less than 5 km suggest emission from the neutron star surface. In 10 sources acceptable fits can only be achieved by including soft-line components. With a spectral resolution of the PSPC of 320-450 eV, between 0.6 and 1.2 keV unresolved broad-line features were detected around 0.65, 0.85, and 1.0 keV. The line fluxes range within 10-11 and 10-12 ergs cm-2 s-1, with equivalent widths between 24 and 210 eV. In LMC X-2, 2S 0918-549, and 4U 1254-690, line emission is indicated for the first time. The soft emission observed in 4U 0614+091 compares with recent ASCA results, with a new feature indicated at 1.31 keV. The deduced line fluxes in 4U 1820-30 and Cyg X-2 showed variability of a factor of 2 within timescales of 1-2 days. Average fluxes of line components in 4U 1820-30 varied by the same factor over a

Hard X-ray balloon observations of compact galactic and extragalactic X-ray sources

International Nuclear Information System (INIS)

Staubert, R.; Kendziorra, E.; Pietsch, W.; Proctor, R.J.; Reppin, C.; Steinle, H.; Truemper, J.; Voges, W.

1981-01-01

A balloon program in hard X-ray astronomy (20-200 keV) is jointly pursued by the Astronomisches Institut der Universitaet Tuebingen (AIT) and the Max Planck-Institut fuer Extraterrestrische Physik in Garching (MPE). Since 1973 nine succussful balloon flights have been performed from Texas and Australia. Here results on Centaurus A and on several galactic binary X-ray sources are summarized. In particular the high energy photon spectrum of Hercules X-1 and the evidence for the cyclotron line feature which was discovered by us in 1976 is reviewed. (orig.)

REFINED NEUTRON STAR MASS DETERMINATIONS FOR SIX ECLIPSING X-RAY PULSAR BINARIES

International Nuclear Information System (INIS)

Rawls, Meredith L.; Orosz, Jerome A.; McClintock, Jeffrey E.; Torres, Manuel A. P.; Bailyn, Charles D.; Buxton, Michelle M.

2011-01-01

We present an improved method for determining the mass of neutron stars in eclipsing X-ray pulsar binaries and apply the method to six systems, namely, Vela X-1, 4U 1538-52, SMC X-1, LMC X-4, Cen X-3, and Her X-1. In previous studies to determine neutron star mass, the X-ray eclipse duration has been approximated analytically by assuming that the companion star is spherical with an effective Roche lobe radius. We use a numerical code based on Roche geometry with various optimizers to analyze the published data for these systems, which we supplement with new spectroscopic and photometric data for 4U 1538-52. This allows us to model the eclipse duration more accurately and thus calculate an improved value for the neutron star mass. The derived neutron star mass also depends on the assumed Roche lobe filling factor β of the companion star, where β = 1 indicates a completely filled Roche lobe. In previous work a range of β between 0.9 and 1.0 was usually adopted. We use optical ellipsoidal light-curve data to constrain β. We find neutron star masses of 1.77 ± 0.08 M sun for Vela X-1, 0.87 ± 0.07 M sun for 4U 1538-52 (eccentric orbit), 1.00 ± 0.10 M sun for 4U 1538-52 (circular orbit), 1.04 ± 0.09 M sun for SMC X-1, 1.29 ± 0.05 M sun for LMC X-4, 1.49 ± 0.08 M sun for Cen X-3, and 1.07 ± 0.36 M sun for Her X-1. We discuss the limits of the approximations that were used to derive the earlier mass determinations, and we comment on the implications our new masses have for observationally refining the upper and lower bounds of the neutron star mass distribution.

Applications for X-ray detectors in astrophysics

International Nuclear Information System (INIS)

Remillard, R.A.

2003-01-01

Full text: Position-sensitive X-Ray detectors continue to playa central role in high-energy astrophysics. The current science goals are reviewed with emphasis on requirements in terms of camera performance. Wide-field imaging techniques, including coded mask cameras, are an essential part of space programs because of the transient nature of high-priority targets, e.g. eruptions from black-hole binaries and cosmic explosions such as gamma ray bursts. Pointing X-ray telescopes are being planned with a wide range of photon energies and with collection designs that include both mirrors and coded masks. Requirements for high spectral resolution and high time resolution are driven by diverse types of X-ray sources such as msec pulsars, quasars with emission-line profiles shaped by general relativity, and X-ray binaries that exhibit quasi-periodic oscillations in the range of 40-1300 Hz. Many laboratories and universities are involved in space-qualification of new detector technologies, e.g. CZT cameras, X-ray calorimeters, new types of CCDs, and GEM detectors. Even X-ray interferometry is on the horizon of NASA's science roadmap. The difficulties in advancing new technologies for space science applications require careful coordinations between industry and science groups in order to solve science problems while minimizing risk

Optical eclipses and precessional effects in the X-ray binary system HD 77581=4U 0900-40

International Nuclear Information System (INIS)

Khruzina, T.S.; Cherepashchuk, A.M.

1982-01-01

The longperiod (P=93.3sup(d)) variability of the amplitude and shape of the optical light curves of the X-ray binary HD 77581 has been discovered from the analysis of all published photometric data. The 93.3-day period is presumably the period of the forced precession of the rotational axis of the optical star. It is shown that the system HD 77581 appears to be an eclipsing binary in the optical range with the amplitude of the ellipsoidal variability approximately 0sup(m).04 and the depth of the eclipse reaching approximately 0sup(m).04. The eclipses are caused by the gaseous streams and the accreting structure, the orientation of which in the binary system is varying with the precession period of the optical star. The estimates of the parameters of the system are obtained. It is shown that the parameter of the Roche Lobe filling for the optical star is μ < 1. The mass of the neutron star is Msub(x)=(1.6+-0.3) Msub(Sun), where Msub(Sun) is the solar mass. The forced precession of the optical star is connected with the non-perpendicularity of its rotational axis to the orbit plane of the binary system. This non-perpendicularity may be a result of supernova explosion in a close binary system

Galaxies in the X-ray Band

Science.gov (United States)

Hornschemeier, Ann

2008-01-01

This talk will provide a brief review of progress on X-ray emission from normal (non-AGN) galaxy populations, including important constraints on the evolution of accreting binary populations over important cosmological timescales. We will also look to the future, anticipating constraints from near-term imaging hard X-ray missions such as NuSTAR, Simbol-X and NeXT and then the longer-term prospects for studying galaxies with the Generation-X mission.

Interacting binaries

International Nuclear Information System (INIS)

Eggleton, P.P.; Pringle, J.E.

1985-01-01

This volume contains 15 review articles in the field of binary stars. The subjects reviewed span considerably, from the shortest period of interacting binaries to the longest, symbiotic stars. Also included are articles on Algols, X-ray binaries and Wolf-Rayet stars (single and binary). Contents: Preface. List of Participants. Activity of Contact Binary Systems. Wolf-Rayet Stars and Binarity. Symbiotic Stars. Massive X-ray Binaries. Stars that go Hump in the Night: The SU UMa Stars. Interacting Binaries - Summing Up

A TEST OF THE NATURE OF THE FE K LINE IN THE NEUTRON STAR LOW-MASS X-RAY BINARY SERPENS X-1

Energy Technology Data Exchange (ETDEWEB)

Chiang, Chia-Ying; Cackett, Edward M. [Department of Physics and Astronomy, Wayne State University, 666 W. Hancock, Detroit, MI 48202 (United States); Miller, Jon M. [Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI48109-1046 (United States); Barret, Didier [Universite de Toulouse, UPS-OMP, Toulouse (France); Fabian, Andy C.; Parker, Michael L. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); D’Aì, Antonino [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, via U. La Malfa 153, I-90146 Palermo (Italy); Bhattacharyya, Sudip [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Burderi, Luciano [Dipartimento di Fisica, Università degli Studi di Cagliari, SP Monserrato-Sestu, KM 0.7, I-09042 Monserrato (Italy); Salvo, Tiziana Di; Iaria, Rosario [Dipartimento di Fisica e Chimica, Universitá di Palermo, via Archirafi 36, I-90123 Palermo (Italy); Egron, Elise [INAF-Osservatorio Astronomico di Cagliari, via della Scienza 5, I-09047 Selargius (Italy); Homan, Jeroen [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue 37-582D, Cambridge, MA 02139 (United States); Lin, Dacheng [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Miller, M. Coleman, E-mail: ft8320@wayne.edu [Department of Astronomy and Joint Space-Science Institute, University of Maryland, College Park, MD 20742-2421 (United States)

2016-04-20

Broad Fe K emission lines have been widely observed in the X-ray spectra of black hole systems as well as in neutron star systems. The intrinsically narrow Fe K fluorescent line is generally believed to be part of the reflection spectrum originating in an illuminated accretion disk which is broadened by strong relativistic effects. However, the nature of the lines in neutron star low-mass X-ray binaries (LMXBs) has been a matter of debate. We therefore obtained the longest, high-resolution X-ray spectrum of a neutron star LMXB to date with a 300 ks Chandra High Energy Transmission Grating Spectrometer (HETGS) observation of Serpens X-1. The observation was taken under the “continuous clocking” mode, and thus was free of photon pile-up effects. We carry out a systematic analysis and find that the blurred reflection model fits the Fe line of Serpens X-1 significantly better than a broad Gaussian component does, implying that the relativistic reflection scenario is much preferred. Chandra HETGS also provides a highest spectral resolution view of the Fe K region and we find no strong evidence for additional narrow lines.

Correlated Radial Velocity and X-Ray Variations in HD 154791/4U 1700+24

Science.gov (United States)

Galloway, Duncan K.; Sokoloski, J. L.; Kenyon, Scott J.

2002-12-01

We present evidence for approximately 400 day variations in the radial velocity of HD 154791 (V934 Her), the suggested optical counterpart of 4U 1700+24. The variations are correlated with the previously reported ~400 day variations in the X-ray flux of 4U 1700+24, which supports the association of these two objects, as well as the identification of this system as the second known X-ray binary in which a neutron star accretes from the wind of a red giant. The HD 154791 radial velocity variations can be fitted with an eccentric orbit with period 404+/-3 days, amplitude K=0.75+/-0.12kms-1, and eccentricity e=0.26+/-0.15. There are also indications of variations on longer timescales >~2000 days. We have reexamined all available All-Sky Monitor (ASM) data following an unusually large X-ray outburst in 1997-1998 and confirm that the 1 day averaged 2-10 keV X-ray flux from 4U 1700+24 is modulated with a period of 400+/-20 days. The mean profile of the persistent X-ray variations was approximately sinusoidal, with an amplitude of 0.108+/-0.012 ASM counts s-1 (corresponding to 31% rms). The epoch of X-ray maximum was approximately 40 days after the time of periastron, according to the eccentric orbital fit. If the 400 day oscillations from HD 154791/4U 1700+24 are due to orbital motion, then the system parameters are probably close to those of the only other neutron star symbiotic-like binary, GX 1+4. We discuss the similarities and differences between these two systems.

Superorbital Period in the high mass X-ray binary 2S 0114+650

Science.gov (United States)

Farrell, S.; Sood, R.; O'Neill, P.

2004-05-01

We report the identification of a superorbital period in the high mass X-ray binary 2S 0114+650. RXTE ASM observations of this object from 1996 Jan 5 to 2003 May 26 show the presence of a modulation at a period of 30.7 +/- 0.2 days. This period is detected using a Lomb-Scargle periodogram, and has a false-alarm probability of 5E-12. Epoch folding of the data gives an ephemeris of JD 2450079.4 (+/- 0.7) +30.7 (+/- 0.2)N, where N is the cycle number, with phase zero defined as the modulation minimum, and a full amplitude of 60 +/- 20%.

Active Galactic Nucleus Obscuration from Winds: From Dusty Infrared-Driven to Warm and X-Ray Photoionized

Science.gov (United States)

Dorodnitsyn, Anton V.; Kallman, Timothy R.

2012-01-01

We present calculations of active galactic nucleus winds at approx.parsec scales along with the associated obscuration. We take into account the pressure of infrared radiation on dust grains and the interaction of X-rays from a central black hole with hot and cold plasma. Infrared radiation (IR) is incorporated in radiation-hydrodynamic simulations adopting the flux-limited diffusion approximation. We find that in the range of X-ray luminosities L = 0.05-0.6 L(sub Edd), the Compton-thick part of the flow (aka torus) has an opening angle of approximately 72deg - 75deg regardless of the luminosity. At L > or approx. 0.1, the outflowing dusty wind provides the obscuration with IR pressure playing a major role. The global flow consists of two phases: the cold flow at inclinations (theta) > or approx.70deg and a hot, ionized wind of lower density at lower inclinations. The dynamical pressure of the hot wind is important in shaping the denser IR-supported flow. At luminosities < or = 0.1 L(sub Edd) episodes of outflow are followed by extended periods when the wind switches to slow accretion. Key words: acceleration of particles . galaxies: active . hydrodynamics . methods: numerical Online-only material: color figures

The environment of the wind-wind collision region of η Carinae

Science.gov (United States)

Panagiotou, C.; Walter, R.

2018-02-01

Context. η Carinae is a colliding wind binary hosting two of the most massive stars and featuring the strongest wind collision mechanical luminosity. The wind collision region of this system is detected in X-rays and γ-rays and offers a unique laboratory for the study of particle acceleration and wind magneto-hydrodynamics. Aim. Our main goal is to use X-ray observations of η Carinae around periastron to constrain the wind collision zone geometry and understand the reasons for its variability. Methods: We analysed 10 Nuclear Spectroscopic Telescope Array (NuSTAR) observations, which were obtained around the 2014 periastron. The NuSTAR array monitored the source from 3 to 30 keV, which allowed us to grasp the continuum and absorption parameters with very good accuracy. We were able to identify several physical components and probe their variability. Results: The X-ray flux varied in a similar way as observed during previous periastrons and largely as expected if generated in the wind collision region. The flux detected within 10 days of periastron is lower than expected, suggesting a partial disruption of the central region of the wind collision zone. The Fe Kα line is likely broadened by the electrons heated along the complex shock fronts. The variability of its equivalent width indicates that the fluorescence region has a complex geometry and that the source obscuration varies quickly with the line of sight.

X-ray Outburst in Mira A

OpenAIRE

Karovska, M.; Schlegel, E.; Hack, W.; Wood, B.

2005-01-01

We report here the Chandra ACIS-S detection of a bright soft X-ray transient in the Mira AB interacting symbiotic-like binary. We resolved the system for the first time in the X-rays. Using Chandra and HST images we determined that the unprecedented outburst is likely associated with the cool AGB star (Mira A), the prototype of Mira-type variables. X-rays have never before been detected from an AGB star, and the recent activity signals that the system is undergoing dramatic changes. The total...

Super-Eddington Accretion in the Ultraluminous X-Ray Source NGC 1313 X-2: An Ephemeral Feast

Science.gov (United States)

Weng, Shan-Shan; Zhang, Shuang-Nan; Zhao, Hai-Hui

2014-01-01

We investigate the X-ray spectrum, variability, and the surrounding ionized bubble of NGC 1313 X-2 to explore the physics of super-Eddington accretion. Beyond the Eddington luminosity, the accretion disk of NGC 1313 X-2 is truncated at a large radius (~50 times the innermost stable circular orbit), and displays the similar evolution track with both luminous Galactic black-hole and neutron star X-ray binaries (XRBs). In super-critical accretion, the speed of radiatively driven outflows from the inner disk is mildly relativistic. Such ultra-fast outflows would be overionized and might produce weak Fe K absorption lines, which may be detected by the coming X-ray mission Astro-H. If NGC 1313 X-2 is a massive stellar XRB, the high luminosity indicates that an ephemeral feast is held in the source. That is, the source must be accreting at a hyper-Eddington mass rate to give the super-Eddington emission over ~104-105 yr. The expansion of the surrounding bubble nebula with a velocity of ~100 km s-1 might indicate that it has existed over ~106 yr and is inflated by the radiatively driven outflows from the transient with a duty cycle of activity of ~ a few percent. Alternatively, if the surrounding bubble nebula is produced by line-driven winds, less energy is required than the radiatively driven outflow scenario, and the radius of the Strömgren radius agrees with the nebula size. Our results are in favor of the line-driven winds scenario, which can avoid the conflict between the short accretion age and the apparently much longer bubble age inferred from the expansion velocity in the nebula.

Formation of Low-Mass X-Ray Binaries. II. Common Envelope Evolution of Primordial Binaries with Extreme Mass Ratios

Science.gov (United States)

Kalogera, Vassiliki; Webbink, Ronald F.

1998-01-01

We study the formation of low-mass X-ray binaries (LMXBs) through helium star supernovae in binary systems that have each emerged from a common envelope phase. LMXB progenitors must satisfy a large number of evolutionary and structural constraints, including survival through common envelope evolution, through the post-common envelope phase, where the precursor of the neutron star becomes a Wolf-Rayet star, and survival through the supernova event. Furthermore, the binaries that survive the explosion must reach interaction within a Hubble time and must satisfy stability criteria for mass transfer. These constraints, imposed under the assumption of a symmetric supernova explosion, prohibit the formation of short-period LMXBs transferring mass at sub-Eddington rates through any channel in which the intermediate progenitor of the neutron star is not completely degenerate. Barring accretion-induced collapse, the existence of such systems therefore requires that natal kicks be imparted to neutron stars. We use an analytical method to synthesize the distribution of nascent LMXBs over donor masses and orbital periods and evaluate their birthrate and systemic velocity dispersion. Within the limitations imposed by observational incompleteness and selection effects, and our neglect of secular evolution in the LMXB state, we compare our results with observations. However, our principal objective is to evaluate how basic model parameters (common envelope ejection efficiency, rms kick velocity, primordial mass ratio distribution) influence these results. We conclude that the characteristics of newborn LMXBs are primarily determined by age and stability constraints and the efficiency of magnetic braking and are largely independent of the primordial binary population and the evolutionary history of LMXB progenitors (except for extreme values of the average kick magnitude or of the common envelope ejection efficiency). Theoretical estimates of total LMXB birthrates are not credible

Analysis by X-Ray images of wind blandes waste incorporated in Portland cement

International Nuclear Information System (INIS)

Marques, M.A.

2011-01-01

The wind blandes wastes can be reused in the incorporation in Portland cement, to be used in non-structural constructions. This work shows X-rays images to assessment the space distribution of the wastes in the cement and to evaluate the use of this methodology. Cylindrical specimens were produced according to ABNT NBR 5738 standards. The mass relation of sand, pebbles and cement was 3:2:1 and 10%, 20% and 50% of waste was incorporated in cement specimens. Frontal and upper projections were obtained in X-Rays images. The images showed that the distribution of the waste is homogeneous, consistent with what was intended in this type of incorporation, which can provide uniformity in test results of compressive strength. (author)

VARIABLE O VI AND N V EMISSION FROM THE X-RAY BINARY LMC X-3: HEATING OF THE BLACK HOLE COMPANION

International Nuclear Information System (INIS)

Song Limin; Tripp, Todd M.; Wang, Q. Daniel; Yao Yangsen; Cui Wei; Xue Yongquan; Orosz, Jerome A.; Steeghs, Danny; Steiner, James F.; Torres, Manuel A. P.; McClintock, Jeffrey E.

2010-01-01

Based on high-resolution ultraviolet spectroscopy obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Cosmic Origins Spectrograph, we present new detections of O VI and N V emission from the black hole X-ray binary (XRB) system LMC X-3. We also update the ephemeris of the XRB using recent radial velocity measurements obtained with the echelle spectrograph on the Magellan-Clay telescope. We observe significant velocity variability of the UV emission, and we find that the O VI and N V emission velocities follow the optical velocity curve of the XRB. Moreover, the O VI and N V intensities regularly decrease between binary phase = 0.5 and 1.0, which suggests that the source of the UV emission is increasingly occulted as the B star in the XRB moves from superior to inferior conjunction. These trends suggest that illumination of the B star atmosphere by the intense X-ray emission from the accreting black hole creates a hot spot on one side of the B star, and this hot spot is the origin of the O VI and N V emission. However, the velocity semiamplitude of the ultraviolet emission, K UV ∼ 180 km s -1 , is lower than the optical semiamplitude; this difference could be due to rotation of the B star. Comparison of the FUSE observations taken in 2001 November and 2004 April shows a significant change in the O VI emission characteristics: in the 2001 data, the O VI region shows both broad and narrow emission features, while in 2004 only the narrow O VI emission is clearly present. Rossi X-ray Timing Explorer data show that the XRB was in a high/soft state in the 2001 November epoch but was in a transitional state in 2004 April, so the shape of the X-ray spectrum might change the properties of the region illuminated on the B star and thus change the broad versus narrow characteristics of the UV emission. If our hypothesis about the origin of the highly ionized emission is correct, then careful analysis of the emission occultation could, in principle

SWIFT X-RAY TELESCOPE STUDY OF THE BLACK HOLE BINARY MAXI J1659–152: VARIABILITY FROM A TWO COMPONENT ACCRETION FLOW

Energy Technology Data Exchange (ETDEWEB)

Kalamkar, M.; Klis, M. van der; Heil, L. [Astronomical Institute, “Anton Pannekoek,” University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands); Homan, J., E-mail: maithili@oa-roma.inaf.it [MIT Kavli Institute for Astrophysics and Space Research, 70 Vassar Street, Cambridge, MA 02139 (United States)

2015-08-01

We present an energy dependent X-ray variability study of the 2010 outburst of the black hole X-ray binary MAXI J1659–152 with the Swift X-ray Telescope (XRT). The broadband noise components and the quasi-periodic oscillations (QPO) observed in the power spectra show a strong and varied energy dependence. Combining Swift XRT data with data from the Rossi X-ray Timing Explorer, we report, for the first time, an rms spectrum (fractional rms amplitude as a function of energy) of these components in the 0.5–30 keV energy range. We find that the strength of the low-frequency component (<0.1 Hz) decreases with energy, contrary to the higher frequency components (>0.1 Hz) whose strengths increase with energy. In the context of the propagating fluctuations model for X-ray variability, we suggest that the low-frequency component originates in the accretion disk (which dominates emission below ∼2 keV) and the higher frequency components are formed in the hot flow (which dominates emission above ∼2 keV). As the properties of the QPO suggest that it may have a different driving mechanism, we investigate the Lense–Thirring precession of the hot flow as a candidate model. We also report on the QPO coherence evolution for the first time in the energy band below 2 keV. While there are strong indications that the QPO is less coherent at energies below 2 keV than above 2 keV, the coherence increases with intensity similar to what is observed at energies above 2 keV in other black hole X-ray binaries.

Stellar and solar X-ray polarimetry

Energy Technology Data Exchange (ETDEWEB)

Novick, R [Columbia Univ., New York (USA)

1975-12-01

The scientific motivation for X-ray polarimetry is discussed with particular emphasis on the information that might be obtained on the binary X-ray pulsars in addition to a number of other classes of objects including solar flares. Detailed discussions are given for Thomson-scattering and Bragg-crystal polarimeters with numerical estimates for the sensitivity of various existing and proposed instruments.

A CHANDRA OBSERVATION OF THE ECLIPSING WOLF-RAYET BINARY CQ Cep

Energy Technology Data Exchange (ETDEWEB)

Skinner, Stephen L. [CASA, Univ. of Colorado, Boulder, CO 80309-0389 (United States); Zhekov, Svetozar A. [Space Research and Technology Institute, Akad. G. Bonchev Str., Sofia, 1113 (Bulgaria); Güdel, Manuel [Dept. of Astrophysics, Univ. of Vienna, Türkenschanzstr. 17, A-1180 Vienna (Austria); Schmutz, Werner, E-mail: stephen.skinner@colorado.edu, E-mail: szhekov@space.bas.bg, E-mail: manuel.guedel@univie.ac.at, E-mail: werner.schmutz@pmodwrc.ch [Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC), Dorfstrasse 33, CH-7260 Davos Dorf (Switzerland)

2015-02-01

The short-period (1.64 d) near-contact eclipsing WN6+O9 binary system CQ Cep provides an ideal laboratory for testing the predictions of X-ray colliding wind shock theory at close separation where the winds may not have reached terminal speeds before colliding. We present results of a Chandra X-ray observation of CQ Cep spanning ∼1 day during which a simultaneous Chandra optical light curve was acquired. Our primary objective was to compare the observed X-ray properties with colliding wind shock theory, which predicts that the hottest shock plasma (T ≳ 20 MK) will form on or near the line-of-centers between the stars. The X-ray spectrum is strikingly similar to apparently single WN6 stars such as WR 134 and spectral lines reveal plasma over a broad range of temperatures T ∼ 4-40 MK. A deep optical eclipse was seen as the O star passed in front of the Wolf-Rayet star and we determine an orbital period P {sub orb} = 1.6412400 d. Somewhat surprisingly, no significant X-ray variability was detected. This implies that the hottest X-ray plasma is not confined to the region between the stars, at odds with the colliding wind picture and suggesting that other X-ray production mechanisms may be at work. Hydrodynamic simulations that account for such effects as radiative cooling and orbital motion will be needed to determine if the new Chandra results can be reconciled with the colliding wind picture.

X-ray tube transformer

International Nuclear Information System (INIS)

1980-01-01

An X-ray generator is described which comprises a transmission line transformer including an electrical conductor with a cavity and a second electrical conductor including helical windings disposed along a longitudinal axis within the cavity of the first conductor. The windings have a pitch which varies per unit length along the axis. There is dielectric material in the cavity for insulation and to couple electromagnetically the two conductors in response to an electric current flowing through the conductors, which have an impedance between them; this varies with distance along the axis of the helix of the second conductor. An X-ray tube is disposed along the longitudinal axis within the cavity, for radiating X-rays. The invention increases the voltage of applied voltage pulses at the remote tube-head with a transformer formed by using a spiral delay line geometry to give a tapered-impedance coaxial high voltage multiplier for pulse voltage operation. This transformer is smaller and lighter than previous designs for the same high peak voltage and power ratings. This is important because the penetration capabilities of Flash X-ray equipment increase with voltage, particularly in heavy materials such as steel. (U.K.)

High-energy Emissions from the Pulsar/Be Binary System PSR J2032+4127/MT91 213

Energy Technology Data Exchange (ETDEWEB)

Takata, J. [School of physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Tam, P. H. T. [Institute of Astronomy and Space Science, Sun Yat-Sen University, Guangzhou 510275 (China); Ng, C. W.; Cheng, K. S. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Li, K. L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-2320 (United States); Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Hui, C. Y., E-mail: takata@hust.edu.cn [Department of Astronomy and Space Science, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2017-02-20

PSR J2032+4127 is a radio-loud gamma-ray-emitting pulsar; it is orbiting around a high-mass Be type star with a very long orbital period of 25–50 years, and is approaching periastron, which will occur in late 2017/early 2018. This system comprises a young pulsar and a Be type star, which is similar to the so-called gamma-ray binary PSR B1259–63/LS2883. It is expected therefore that PSR J2032+4127 shows an enhancement of high-energy emission caused by the interaction between the pulsar wind and Be wind/disk around periastron. Ho et al. recently reported a rapid increase in the X-ray flux from this system. In this paper, we also confirm a rapid increase in the X-ray flux along the orbit, while the GeV flux shows no significant change. We discuss the high-energy emissions from the shock caused by the pulsar wind and stellar wind interaction and examine the properties of the pulsar wind in this binary system. We argue that the rate of increase of the X-ray flux observed by Swift indicates (1) a variation of the momentum ratio of the two-wind interaction region along the orbit, or (2) an evolution of the magnetization parameter of the pulsar wind with the radial distance from the pulsar. We also discuss the pulsar wind/Be disk interaction at the periastron passage, and propose the possibility of formation of an accretion disk around the pulsar. We model high-energy emissions through the inverse-Compton scattering process of the cold-relativistic pulsar wind off soft photons from the accretion disk.

The Causal Connection Between Disc and Power-Law Variability in Hard State Black Hole X-Ray Binaries

Science.gov (United States)

Uttley, P.; Wilkinson, T.; Cassatella, P.; Wilms, J.; Pottschimdt, K.; Hanke, M.; Boeck, M.

2010-01-01

We use the XMM-Newton EPIC-pn instrument in timing mode to extend spectral time-lag studies of hard state black hole X-ray binaries into the soft X-ray band. \\Ve show that variations of the disc blackbody emission substantially lead variations in the power-law emission, by tenths of a second on variability time-scales of seconds or longer. The large lags cannot be explained by Compton scattering but are consistent with time-delays due to viscous propagation of mass accretion fluctuations in the disc. However, on time-scales less than a second the disc lags the power-law variations by a few ms, consistent with the disc variations being dominated by X-ray heating by the power-law, with the short lag corresponding to the light-travel time between the power-law emitting region and the disc. Our results indicate that instabilities in the accretion disc are responsible for continuum variability on time-scales of seconds or longer and probably also on shorter time-scales.

A Hard X-Ray Power-Law Spectral Cutoff in Centaurus X-4

DEFF Research Database (Denmark)

Chakrabarty, Deepto; Tomsick, John A.; Grefenstette, Brian W.

2015-01-01

The low-mass X-ray binary Cen X-4 is the brightest and closest (<1.2 kpc) quiescent neutron star transient. Previous 0.5-10 keV X-ray observations of Cen X-4 in quiescence identified two spectral components: soft thermal emission from the neutron star atmosphere and a hard power-law tail of unkno...... behavior with PSR J1023+0038, IGR J18245-2452, and XSS J12270-4859, which have shown transitions between LMXB and radio pulsar modes at a similar X-ray luminosity....

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

Science.gov (United States)

Sibeck, David G.; Allen, R.; Aryan, H.; Bodewits, D.; Brandt, P.; Branduardi-Raymont, G.; Brown, G.; Carter, J. A.; Collado-Vega, Y. M.; Collier, M. R.; Connor, H. K.; Cravens, T. E.; Ezoe, Y.; Fok, M.-C.; Galeazzi, M.; Gutynska, O.; Holmström, M.; Hsieh, S.-Y.; Ishikawa, K.; Koutroumpa, D.; Kuntz, K. D.; Leutenegger, M.; Miyoshi, Y.; Porter, F. S.; Purucker, M. E.; Read, A. M.; Raeder, J.; Robertson, I. P.; Samsonov, A. A.; Sembay, S.; Snowden, S. L.; Thomas, N. E.; von Steiger, R.; Walsh, B. M.; Wing, S.

2018-06-01

Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle observations, guided by the predictions of both local and global numerical simulations, and placed in context by observations from far and extreme ultraviolet (FUV, EUV), hard X-ray, and energetic neutral atom imagers (ENA). Each proposed interaction mechanism (e.g., steady or transient magnetic reconnection, local or global magnetic reconnection, ion pick-up, or the Kelvin-Helmholtz instability) generates diagnostic plasma density structures. The significance of each mechanism to the overall interaction (as measured in terms of atmospheric/ionospheric loss at comets, Venus, and Mars or global magnetospheric/ionospheric convection at Earth) remains to be determined but can be evaluated on the basis of how often the density signatures that it generates are observed as a function of solar wind conditions. This paper reviews efforts to image the diagnostic plasma density structures in the soft (low energy, 0.1-2.0 keV) X-rays produced when high charge state solar wind ions exchange electrons with the exospheric neutrals surrounding solar system obstacles. The introduction notes that theory, local, and global simulations predict the characteristics of plasma boundaries such the bow shock and magnetopause (including location, density gradient, and motion) and regions such as the magnetosheath (including density and width) as a function of location, solar wind conditions, and the particular mechanism operating. In situ measurements confirm the existence of time- and spatial-dependent plasma density structures like the bow shock, magnetosheath, and magnetopause/ionopause at Venus, Mars, comets, and the Earth. However, in situ

Rapid X-Ray Variations of the Geminga Pulsar Wind Nebula

Energy Technology Data Exchange (ETDEWEB)

Hui, C. Y.; Lee, Jongsu [Department of Astronomy and Space Science, Chungnam National University, Daejeon 34134 (Korea, Republic of); Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Tam, P. H. T. [School of Physics and Astronomy, Sun Yat-Sen University, Guangzhou 510275 (China); Takata, J. [Institute of Particle Physics and Astronomy, Huazhong University of Science and Technology, Wuhan (China); Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Ryu, Dongsu, E-mail: cyhui@cnu.ac.kr [Department of Physics, UNIST, Ulsan 44919 (Korea, Republic of)

2017-09-10

A recent study by Posselt et al. reported the deepest X-ray investigation of the Geminga pulsar wind nebula (PWN) by using Chandra X-ray Observatory . In comparison with previous studies of this system, a number of new findings have been reported, and we found that these suggest the possible variabilities in various components of this PWN. This motivates us to carry out a dedicated search for the morphological and spectral variations of this complex nebula. We have discovered variabilities on timescales from a few days to a few months from different components of the nebula. The fastest change occurred in the circumstellar environment at a rate of 80% of the speed of light. One of the most spectacular results is the wiggling of a half light-year long tail as an extension of the jet, which is significantly bent by the ram pressure. The jet wiggling occurred at a rate of about 20% of the speed of light. This twisted structure could possibly be a result of a propagating torsional Alfv́en wave. We have also found evidence of spectral hardening along this tail for a period of about nine months.

A ROSAT Survey of Contact Binary Stars

Science.gov (United States)

Geske, M. T.; Gettel, S. J.; McKay, T. A.

2006-01-01

Contact binary stars are common variable stars that are all believed to emit relatively large fluxes of X-rays. In this work we combine a large new sample of contact binary stars derived from the ROTSE-I telescope with X-ray data from the ROSAT All Sky Survey (RASS) to estimate the X-ray volume emissivity of contact binary stars in the Galaxy. We obtained X-ray fluxes for 140 contact binaries from the RASS, as well as two additional stars observed by the XMM-Newton observatory. From these data we confirm the emission of X-rays from all contact binary systems, with typical luminosities of approximately 1.0×1030 ergs s-1. Combining calculated luminosities with an estimated contact binary space density, we find that contact binaries do not have strong enough X-ray emission to account for a significant portion of the Galactic X-ray background.

Spectral and temporal properties of the X-ray pulsar SMC X-1 at hard X-rays

Science.gov (United States)

Kunz, M.; Gruber, D. E.; Kendziorra, E .; Kretschmar, P.; Maisack, M.; Mony, B.; Staubert, R.; Doebereiner, S.; Englhauser, J.; Pietsch, W.

1993-01-01

The binary X-ray pulsar SMC X- 1 has been observed at hard X-rays with the High Energy X-Ray Experiment (HEXE) on nine occasions between Nov. 1987 and March 1989. A thin thermal bremsstrahlung fit to the phase averaged spectrum yields a plasma temperature (14.4 +/- 1.3) keV and a luminosity above (1.1 +/- 0.1) x 10 exp 38 erg/s in the 20-80 keV band. Pulse period values have been established for three observations, confirming the remarkably stable spin-up trend of SMC X-1. In one of the three observations the pulse profile was seen to deviate from a dominant double pulsation, while at the same time the pulsed fraction was unusually large. For one observation we determined for the first time the pulsed fraction in narrow energy bands. It increases with photon energy from about 20 percent up to over 60 percent in the energy range from 20 to 80 keV.

Detection of Reflection Features in the Neutron Star Low-mass X-Ray Binary Serpens X-1 with NICER

Science.gov (United States)

Ludlam, R. M.; Miller, J. M.; Arzoumanian, Z.; Bult, P. M.; Cackett, E. M.; Chakrabarty, D.; Enoto, T.; Fabian, A. C.; Gendreau, K. C.; Guillot, S.; Homan, J.; Jaisawal, G. K.; Keek, L.; La Marr, B.; Malacaria, C.; Markwardt, C. B.; Steiner, J. F.; Strohmayer, T. E.

2018-05-01

We present Neutron Star Interior Composition Explorer (NICER) observations of the neutron star (NS) low-mass X-ray binary Serpens X-1 during the early mission phase in 2017. With the high spectral sensitivity and low-energy X-ray passband of NICER, we are able to detect the Fe L line complex in addition to the signature broad, asymmetric Fe K line. We confirm the presence of these lines by comparing the NICER data to archival observations with XMM-Newton/Reflection Grating Spectrometer (RGS) and NuSTAR. Both features originate close to the innermost stable circular orbit (ISCO). When modeling the lines with the relativistic line model RELLINE, we find that the Fe L blend requires an inner disk radius of {1.4}-0.1+0.2 R ISCO and Fe K is at {1.03}-0.03+0.13 R ISCO (errors quoted at 90%). This corresponds to a position of {17.3}-1.2+2.5 km and {12.7}-0.4+1.6 km for a canonical NS mass ({M}NS}=1.4 {M}ȯ ) and dimensionless spin value of a = 0. Additionally, we employ a new version of the RELXILL model tailored for NSs and determine that these features arise from a dense disk and supersolar Fe abundance.

Search for Thermal X-ray Features from the Crab nebula with Hitomi Soft X-ray Spectrometer

Science.gov (United States)

Tsujimoto, M.; Mori, K.; Lee, S.; Yamaguchi, H.; Tominaga, N.; Moriya, T.; Sato, T.; Bamba, A.

2017-10-01

The Crab nebula originates from a core-collapse SN in 1054. It has an anomalously low observed ejecta mass for a Fe-core collapse SN. Intensive searches were made for an undetected massive shell to solve this discrepancy. An alternative idea is that the SN1054 is an electron-capture (EC) explosion with a lower explosion energy than Fe-core collapse SNe. In the X-rays, imaging searches were performed for the plasma emission from the shell in the Crab outskirts. However, the extreme brightness hampers access to its vicinity. We used spectroscopic technique using the X-ray micro-calorimeter onboard Hitomi. We searched for the emission or absorption features by the thermal plasma and set a new limit. We re-evaluated the existing data to claim that the X-ray plasma mass is wind). We found that the observed mass limit can be compatible with both SN models if the environment has a low density of wind density parameter for the wind environment.

M31 GLOBULAR CLUSTER STRUCTURES AND THE PRESENCE OF X-RAY BINARIES

International Nuclear Information System (INIS)

Agar, J. R. R.; Barmby, P.

2013-01-01

The Andromeda galaxy, M31, has several times the number of globular clusters found in the Milky Way. It contains a correspondingly larger number of low-mass X-ray binaries (LMXBs) associated with globular clusters, and as such can be used to investigate the cluster properties that lead to X-ray binary formation. The best tracer of the spatial structure of M31 globulars is the high-resolution imaging available from the Hubble Space Telescope (HST), and we have used HST data to derive structural parameters for 29 LMXB-hosting M31 globular clusters. These measurements are combined with structural parameters from the literature for a total of 41 (of 50 known) LMXB clusters and a comparison sample of 65 non-LMXB clusters. Structural parameters measured in blue bandpasses are found to be slightly different (smaller core radii and higher concentrations) than those measured in red bandpasses; this difference is enhanced in LMXB clusters and could be related to stellar population differences. Clusters with LMXBs show higher collision rates for their mass compared to clusters without LMXBs, and collision rates estimated at the core radius show larger offsets than rates estimated at the half-light radius. These results are consistent with the dynamical formation scenario for LMXBs. A logistic regression analysis finds that, as expected, the probability of a cluster hosting an LMXB increases with increasing collision rate and proximity to the galaxy center. The same analysis finds that probability of a cluster hosting an LMXB decreases with increasing cluster mass at a fixed collision rate, although we caution that this could be due to sample selection effects. Metallicity is found to be a less important predictor of LMXB probability than collision rate, mass, or distance, even though LMXB clusters have a higher metallicity on average. This may be due to the interaction of location and metallicity: a sample of M31 LMXBs with a greater range in galactocentric distance would

CHANDRA ACIS SURVEY OF X-RAY POINT SOURCES IN NEARBY GALAXIES. II. X-RAY LUMINOSITY FUNCTIONS AND ULTRALUMINOUS X-RAY SOURCES

Energy Technology Data Exchange (ETDEWEB)

Wang, Song; Qiu, Yanli; Liu, Jifeng [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Bregman, Joel N., E-mail: songw@bao.ac.cn, E-mail: jfliu@bao.ac.cn [University of Michigan, Ann Arbor, MI 48109 (United States)

2016-09-20

Based on the recently completed Chandra /ACIS survey of X-ray point sources in nearby galaxies, we study the X-ray luminosity functions (XLFs) for X-ray point sources in different types of galaxies and the statistical properties of ultraluminous X-ray sources (ULXs). Uniform procedures are developed to compute the detection threshold, to estimate the foreground/background contamination, and to calculate the XLFs for individual galaxies and groups of galaxies, resulting in an XLF library of 343 galaxies of different types. With the large number of surveyed galaxies, we have studied the XLFs and ULX properties across different host galaxy types, and confirm with good statistics that the XLF slope flattens from lenticular ( α ∼ 1.50 ± 0.07) to elliptical (∼1.21 ± 0.02), to spirals (∼0.80 ± 0.02), to peculiars (∼0.55 ± 0.30), and to irregulars (∼0.26 ± 0.10). The XLF break dividing the neutron star and black hole binaries is also confirmed, albeit at quite different break luminosities for different types of galaxies. A radial dependency is found for ellipticals, with a flatter XLF slope for sources located between D {sub 25} and 2 D {sub 25}, suggesting the XLF slopes in the outer region of early-type galaxies are dominated by low-mass X-ray binaries in globular clusters. This study shows that the ULX rate in early-type galaxies is 0.24 ± 0.05 ULXs per surveyed galaxy, on a 5 σ confidence level. The XLF for ULXs in late-type galaxies extends smoothly until it drops abruptly around 4 × 10{sup 40} erg s{sup −1}, and this break may suggest a mild boundary between the stellar black hole population possibly including 30 M {sub ⊙} black holes with super-Eddington radiation and intermediate mass black holes.

The X-Ray Evolution of the Symbiotic Star V407 Cygni During Its 2010 Outburst

Science.gov (United States)

Mukai, K.; Nelson, T.; Chomiuk, L.; Donato, D.; Sokoloski, J.

2011-01-01

We present a summary of Swift and Suzaku X-ray observations of the 2010 nova outburst of the symbiotic star, V407 Cyg. The Suzaku spectrum obtained on day 30 indicates the presence of the supersoft component from the white dwarf surface, as well as optically thin component from the shock between the nova ejecta and the Mira wind. The Swift observations then allow us to track the evolution of both components from day 4 to day 150. Most notable is the sudden brightening of the optically think component around day 20. We identify this as the time when the blast wave reached the immediate vicinity of the photosphere of the Mira. We have developed a simplified model of the blast wave-wind interaction that can reproduce the gross features of the X-ray evolution of V407 Cyg. If the model is correct, the binary separation is likely to be large and the mass loss rate of the Mira is likely to be relatively low.

Atmospheric NLTE models for the spectroscopic analysis of blue stars with winds. III. X-ray emission from wind-embedded shocks

Science.gov (United States)

Carneiro, L. P.; Puls, J.; Sundqvist, J. O.; Hoffmann, T. L.

2016-05-01

Context. Extreme ultraviolet (EUV) and X-ray radiation emitted from wind-embedded shocks in hot, massive stars can affect the ionization balance in their outer atmospheres and can be the mechanism responsible for producing highly ionized atomic species detected in stellar wind UV spectra. Aims: To allow for these processes in the context of spectral analysis, we have implemented the emission from wind-embedded shocks and related physics into our unified, NLTE model atmosphere/spectrum synthesis code FASTWIND. Methods: The shock structure and corresponding emission is calculated as a function of user-supplied parameters (volume filling factor, radial stratification of shock strength, and radial onset of emission). We account for a temperature and density stratification inside the postshock cooling zones, calculated for radiative and adiabatic cooling in the inner and outer wind, respectively. The high-energy absorption of the cool wind is considered by adding important K-shell opacities, and corresponding Auger ionization rates have been included in the NLTE network. To test our implementation and to check the resulting effects, we calculated a comprehensive model grid with a variety of X-ray emission parameters. Results: We tested and verified our implementation carefully against corresponding results from various alternative model atmosphere codes, and studied the effects from shock emission for important ions from He, C, N, O, Si, and P. Surprisingly, dielectronic recombination turned out to play an essential role for the ionization balance of O iv/O v (particularly in dwarfs with Teff~ 45 000 K). Finally, we investigated the frequency dependence and radial behavior of the mass absorption coefficient, κν(r), which is important in the context of X-ray line formation in massive star winds. Conclusions: In almost all of the cases considered, direct ionization is of major influence because of the enhanced EUV radiation field, and Auger ionization only affects N vi

Design and Tests of the Hard X-ray Polarimeter X-Calibur

Directory of Open Access Journals (Sweden)

M. Beilicke

2014-12-01

Full Text Available X-ray polarimetry promises to give qualitatively new information bout high-energy astrophysical sources, such as binary black hole  systems, micro-quasars, active galactic nuclei, and gamma-ray bursts. We designed, built and tested ahard X-ray polarimeter, X-Calibur, to be used in the focal plane of the InFOCuS grazing incidence hard X-ray telescope.X-Calibur combines a low-Z Compton scatterer with a CZT detector assembly to measure the polarization of 20−60 keV X-rays making use of the fact that polarized photons Compton scatter preferentially perpendicular to the electric field orientation; in principal, a similar space-borne experiment could be operated in the 5−100 keV regime. X-Calibur achieves a high detection efficiency of order unity.

LOBSTER - New Space X-Ray telescopes

International Nuclear Information System (INIS)

Hudec, R.; Pina, L.; Simon, V.; Sveda, L.; Inneman, A.; Semencova, V.; Skulinova, M.

2007-01-01

We discuss the technological and scientific aspects of fully innovative very wide-field X-ray telescopes with high sensitivity. The prototypes of Lobster telescopes designed, developed and tested are very promising, allowing the proposals for space projects with very wide-field Lobster Eye X-ray optics to be considered for the first time. The novel telescopes will monitor the sky with unprecedented sensitivity and angular resolution of order of 1 arcmin. They are expected to contribute essentially to study of various astrophysical objects such as AGN, SNe, Gamma-ray bursts (GRBs), X-ray flashes (XRFs), galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc. For example, the Lobster optics based X-ray All Sky Monitor is capable to detect around 20 GRBs and 8 XRFs yearly and this will surely significantly contribute to the related science

Disk Disruptions and X-ray Intensity Excursions in Cyg X-2, LMC X-3 and Cyg X-3

Science.gov (United States)

Boyd, P. T.; Smale, A. P.

2001-05-01

The RXTE All Sky Monitor soft X-ray light curves of many X-ray binaries show long-term intensity variations (a.k.a "superorbital periodicities") that have been ascribed to precession of a warped, tilted accretion disk around the X-ray source. We have found that the excursion times between X-ray minima in Cyg X-2 can be characterized as a series of integer multiples of the 9.8 binary orbital period, (as opposed to the previously reported stable 77.7 day single periodicity, or a single modulation whose period changes slowly with time). While the data set is too short for a proper statistical analysis, it is clear that the length of any given intensity excursion cannot be used to predict the next (integer) excursion length in the series. In the black hole candidate system LMC X-3, the excursion times are shown to be related to each other by rational fractions. We find that the long term light curve of the unusual galactic X-ray jet source Cyg X-3 can also be described as a series of intensity excursions related to each other by integer multiples of a fundamental underlying clock. In the latter cases, the clock is apparently not related to the known binary periods. A unified physical model, involving both an inclined accretion disk and a fixed-probability disk disruption mechanism is presented, and compared with three-body scattering results. Each time the disk passes through the orbital plane it experiences a fixed probability P that it will disrupt. This model has testable predictions---the distribution of integers should resemble that of an atomic process with a characteristic half life. Further analysis can support or refute the model, and shed light on what system parameters effectively set the value of P.

Formation of the black-hole binary M33 X-7 through mass exchange in a tight massive system.

Science.gov (United States)

Valsecchi, Francesca; Glebbeek, Evert; Farr, Will M; Fragos, Tassos; Willems, Bart; Orosz, Jerome A; Liu, Jifeng; Kalogera, Vassiliki

2010-11-04

The X-ray source M33 X-7 in the nearby galaxy Messier 33 is among the most massive X-ray binary stellar systems known, hosting a rapidly spinning, 15.65M(⊙) black hole orbiting an underluminous, 70M(⊙) main-sequence companion in a slightly eccentric 3.45-day orbit (M(⊙), solar mass). Although post-main-sequence mass transfer explains the masses and tight orbit, it leaves unexplained the observed X-ray luminosity, the star's underluminosity, the black hole's spin and the orbital eccentricity. A common envelope phase, or rotational mixing, could explain the orbit, but the former would lead to a merger and the latter to an overluminous companion. A merger would also ensue if mass transfer to the black hole were invoked for its spin-up. Here we report simulations of evolutionary tracks which reveal that if M33 X-7 started as a primary body of 85M(⊙)-99M(⊙) and a secondary body of 28M(⊙)-32M(⊙), in a 2.8-3.1-d orbit, its observed properties can be consistently explained. In this model, the main-sequence primary transfers part of its envelope to the secondary and loses the rest in a wind; it ends its life as a ∼16M(⊙) helium star with an iron-nickel core that collapses to a black hole (with or without an accompanying supernova). The release of binding energy, and possibly collapse asymmetries, 'kick' the nascent black hole into an eccentric orbit. Wind accretion explains the X-ray luminosity, and the black-hole spin can be natal.

Radiation parameters of the x-ray binary A 0535 + 26 = HDE 245770 based on polarization and photometric data

International Nuclear Information System (INIS)

Larionov, V.M.

1988-01-01

Analysis of the observations of Shakhovskaya et al. has led to the identification in the radiation of the x-ray binary system A 0535 + 26 = HDE 245770 of two components associated with an optical 09 III star and an accretion disk around a neutron star. The parameters of the interstellar polarization agree with Serkowski's formula and the observations of neighboring stars. The variability of the brightness of the system observed in the optical and infrared ranges can be explained by changes in the contribution of the accretion disk to the total emission of the system. The values obtained for the parameters of the intrinsic polarization, interpreted in the framework of the proposed model, suggest directions of the polarization vectors in the infrared and x-ray range

Super-eddington accretion in the ultraluminous x-ray source NGC 1313 X-2: An ephemeral feast

Energy Technology Data Exchange (ETDEWEB)

Weng, Shan-Shan [Department of Physics, Xiangtan University, Xiangtan 411105 (China); Zhang, Shuang-Nan; Zhao, Hai-Hui, E-mail: wengss@ihep.ac.cn, E-mail: zhangsn@ihep.ac.cn, E-mail: zhaohh@ihep.ac.cn [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2014-01-10

We investigate the X-ray spectrum, variability, and the surrounding ionized bubble of NGC 1313 X-2 to explore the physics of super-Eddington accretion. Beyond the Eddington luminosity, the accretion disk of NGC 1313 X-2 is truncated at a large radius (∼50 times the innermost stable circular orbit), and displays the similar evolution track with both luminous Galactic black-hole and neutron star X-ray binaries (XRBs). In super-critical accretion, the speed of radiatively driven outflows from the inner disk is mildly relativistic. Such ultra-fast outflows would be overionized and might produce weak Fe K absorption lines, which may be detected by the coming X-ray mission Astro-H. If NGC 1313 X-2 is a massive stellar XRB, the high luminosity indicates that an ephemeral feast is held in the source. That is, the source must be accreting at a hyper-Eddington mass rate to give the super-Eddington emission over ∼10{sup 4}-10{sup 5} yr. The expansion of the surrounding bubble nebula with a velocity of ∼100 km s{sup –1} might indicate that it has existed over ∼10{sup 6} yr and is inflated by the radiatively driven outflows from the transient with a duty cycle of activity of ∼ a few percent. Alternatively, if the surrounding bubble nebula is produced by line-driven winds, less energy is required than the radiatively driven outflow scenario, and the radius of the Strömgren radius agrees with the nebula size. Our results are in favor of the line-driven winds scenario, which can avoid the conflict between the short accretion age and the apparently much longer bubble age inferred from the expansion velocity in the nebula.

Super-eddington accretion in the ultraluminous x-ray source NGC 1313 X-2: An ephemeral feast

International Nuclear Information System (INIS)

Weng, Shan-Shan; Zhang, Shuang-Nan; Zhao, Hai-Hui

2014-01-01

We investigate the X-ray spectrum, variability, and the surrounding ionized bubble of NGC 1313 X-2 to explore the physics of super-Eddington accretion. Beyond the Eddington luminosity, the accretion disk of NGC 1313 X-2 is truncated at a large radius (∼50 times the innermost stable circular orbit), and displays the similar evolution track with both luminous Galactic black-hole and neutron star X-ray binaries (XRBs). In super-critical accretion, the speed of radiatively driven outflows from the inner disk is mildly relativistic. Such ultra-fast outflows would be overionized and might produce weak Fe K absorption lines, which may be detected by the coming X-ray mission Astro-H. If NGC 1313 X-2 is a massive stellar XRB, the high luminosity indicates that an ephemeral feast is held in the source. That is, the source must be accreting at a hyper-Eddington mass rate to give the super-Eddington emission over ∼10 4 -10 5 yr. The expansion of the surrounding bubble nebula with a velocity of ∼100 km s –1 might indicate that it has existed over ∼10 6 yr and is inflated by the radiatively driven outflows from the transient with a duty cycle of activity of ∼ a few percent. Alternatively, if the surrounding bubble nebula is produced by line-driven winds, less energy is required than the radiatively driven outflow scenario, and the radius of the Strömgren radius agrees with the nebula size. Our results are in favor of the line-driven winds scenario, which can avoid the conflict between the short accretion age and the apparently much longer bubble age inferred from the expansion velocity in the nebula.

INVERSE COMPTON X-RAY EMISSION FROM SUPERNOVAE WITH COMPACT PROGENITORS: APPLICATION TO SN2011fe

International Nuclear Information System (INIS)

Margutti, R.; Soderberg, A. M.; Chomiuk, L.; Milisavljevic, D.; Foley, R. J.; Slane, P.; Moe, M.; Chevalier, R.; Hurley, K.; Hughes, J. P.; Fransson, C.; Barthelmy, S.; Cummings, J.; Boynton, W.; Enos, H.; Fellows, C.; Briggs, M.; Connaughton, V.; Costa, E.; Del Monte, E.

2012-01-01

We present a generalized analytic formalism for the inverse Compton X-ray emission from hydrogen-poor supernovae and apply this framework to SN 2011fe using Swift X-Ray Telescope (XRT), UVOT, and Chandra observations. We characterize the optical properties of SN 2011fe in the Swift bands and find them to be broadly consistent with a 'normal' SN Ia, however, no X-ray source is detected by either XRT or Chandra. We constrain the progenitor system mass-loss rate M-dot -9 M ☉ yr -1 (3σ c.l.) for wind velocity v w = 100 km s –1 . Our result rules out symbiotic binary progenitors for SN 2011fe and argues against Roche lobe overflowing subgiants and main-sequence secondary stars if ∼> 1% of the transferred mass is lost at the Lagrangian points. Regardless of the density profile, the X-ray non-detections are suggestive of a clean environment (n CSM –3 ) for 2 × 10 15 ∼ 16 cm around the progenitor site. This is either consistent with the bulk of material being confined within the binary system or with a significant delay between mass loss and supernova explosion. We furthermore combine X-ray and radio limits from Chomiuk et al. to constrain the post-shock energy density in magnetic fields. Finally, we searched for the shock breakout pulse using gamma-ray observations from the Interplanetary Network and find no compelling evidence for a supernova-associated burst. Based on the compact radius of the progenitor star we estimate that the shock breakout pulse was likely not detectable by current satellites.

A study of the cross-correlation and time lag in black hole X-ray binary XTE J1859+226

Science.gov (United States)

Pei, Songpeng; Ding, Guoqiang; Li, Zhibing; Lei, Yajuan; Yuen, Rai; Qu, Jinlu

2017-07-01

With Rossi X-ray Timing Explorer (RXTE) data, we systematically study the cross-correlation and time lag in all spectral states of black hole X-ray binary (BHXB) XTE J1859+226 in detail during its entire 1999-2000 outburst that lasted for 166 days. Anti-correlations and positive correlations and their respective soft and hard X-ray lags are only detected in the first 100 days of the outburst when the luminosity is high. This suggests that the cross-correlations may be related to high luminosity. Positive correlations are detected in every state of XTE J1859+226, viz., hard state, hard-intermediate state (HIMS), soft-intermediate state (SIMS) and soft state. However, anti-correlations are only detected in HIMS and SIMS, anti-correlated hard lags are only detected in SIMS, while anti-correlated soft lags are detected in both HIMS and SIMS. Moreover, the ratio of the observations with anti-correlated soft lags to hard lags detected in XTE J1859+226 is significantly different from that in neutron star low-mass X-ray binaries (NS LMXBs). So far, anti-correlations are never detected in the soft state of BHXBs but detected in every branch or state of NS LMXBs. This may be due to the origin of soft seed photons in BHXBs is confined to the accretion disk and, for NS LMXBs, from both accretion disk and the surface of the NS. We notice that the timescale of anti-correlated time lags detected in XTE J1859+226 is similar with that of other BHXBs and NS LMXBs. We suggest that anti-correlated soft lag detected in BHXB may result from fluctuation in the accretion disk as well as NS LMXB.

Modulated High-Energy Gamma-Ray Emission from the Micro-quasar Cygnus X-3

International Nuclear Information System (INIS)

Abdo, A.A.; Cheung, C.C.; Dermer, C.D.; Grove, J.E.; Johnson, W.N.; Lovellette, M.N.; Makeev, A.; Ray, P.S.; Strickman, M.S.; Wood, K.S.; Abdo, A.A.; Cheung, C.C.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R.D.; Bloom, E.D.; Borgland, A.W.; Cameron, R.A.; Chiang, J.; Claus, R.; Digel, S.W.; Silva, E.D.E.; Drell, P.S.; Dubois, R.; Focke, W.B.; Glanzman, T.; Godfrey, G.; Hayashida, M.; Johannesson, G.; Johnson, A.S.; Kamae, T.; Kocian, M.L.; Lande, J.; Madejski, G.M.; Michelson, P.F.; Mitthumsiri, W.; Monzani, M.E.; Moskalenko, I.V.; Murgia, S.; Nolan, P.L.; Paneque, D.; Reimer, A.; Reimer, O.; Rochester, L.S.; Romani, R.W.; Tanaka, T.; Thayer, J.B.; Tramacere, A.; Uchiyama, Y.; Usher, T.L.; Waite, A.P.; Wang, P.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R.D.; Bloom, E.D.; Borgland, A.W.; Cameron, R.A.; Chiang, J.; Claus, R.; Digel, S.W.; Silva, E.D.E.; Drell, P.S.; Dubois, R.; Focke, W.B.; Glanzman, T.; Godfrey, G.; Hayashida, M.; Johannesson, G.; Johnson, A.S.; Kamae, T.; Kocian, M.L.; Lande, J.; Madejski, G.M.; Michelson, P.F.; Mitthumsiri, W.; Monzani, M.E.; Moskalenko, I.V.; Murgia, S.; Nolan, P.L.; Paneque, D.; Reimer, A.; Reimer, O.; Rochester, L.S.; Romani, R.W.; Tanaka, T.; Thayer, J.B.; Tramacere, A.; Uchiyama, Y.; Usher, T.L.; Waite, A.P.; Wang, P.; Axelsson, M.; Hjalmarsdotter, L.; Axelsson, M.; Conrad, J.; Hjalmarsdotter, L.; Jackson, M.S.; Meurer, C.; Ryde, F.; Ylinen, T.; Baldini, L.; Bellazzini, R.; Brez, A.; Kuss, M.; Latronico, L.; Omodei, N.; Pesce-Rollins, M.; Razzano, M.; Sgro, C.; Ballet, J.; Casandjian, J.M.; Chaty, S.; Corbel, S.; Grenier, I.A.; Koerding, E.; Rodriguez, J.; Starck, J.L.; Tibaldo, L.

2009-01-01

Micro-quasars are accreting black holes or neutron stars in binary systems with associated relativistic jets. Despite their frequent outburst activity, they have never been unambiguously detected emitting high-energy gamma rays. The Fermi Large Area Telescope (LAT) has detected a variable high-energy source coinciding with the position of the x-ray binary and micro-quasar Cygnus X-3. Its identification with Cygnus X-3 is secured by the detection of its orbital period in gamma rays, as well as the correlation of the LAT flux with radio emission from the relativistic jets of Cygnus X-3. The gamma-ray emission probably originates from within the binary system, opening new areas in which to study the formation of relativistic jets. (authors)

DISCOVERY OF AN ULTRACOMPACT GAMMA-RAY MILLISECOND PULSAR BINARY CANDIDATE

Energy Technology Data Exchange (ETDEWEB)

Kong, Albert K. H.; Jin, Ruolan; Yen, T.-C.; Tam, P. H. T.; Lin, L. C. C. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Hu, C.-P. [Graduate Institute of Astronomy, National Central University, Jhongli 32001, Taiwan (China); Hui, C. Y.; Park, S. M. [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Takata, J.; Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Kim, C. L., E-mail: akong@phys.nthu.edu.tw [Department of Physics and Astronomy, Seoul National University (Korea, Republic of)

2014-10-20

We report multi-wavelength observations of the unidentified Fermi object 2FGL J1653.6-0159. With the help of high-resolution X-ray observations, we have identified an X-ray and optical counterpart to 2FGL J1653.6-0159. The source exhibits a periodic modulation of 75 minutes in the optical and possibly also in the X-ray. We suggest that 2FGL J1653.6-0159 is a compact binary system with an orbital period of 75 minutes. Combining the gamma-ray and X-ray properties, 2FGL J1653.6-0159 is potentially a black-widow-/redback-type gamma-ray millisecond pulsar (MSP). The optical and X-ray light curve profiles show that the companion is mildly heated by the high-energy emission and that the X-rays are from intrabinary shock. Although no radio pulsation has yet been detected, we estimated that the spin period of the MSP is ∼ 2 ms based on a theoretical model. If pulsation can be confirmed in the future, 2FGL J1653.6-0159 will become the first ultracompact rotation-powered MSP.

Scientists Find X Rays from Stellar Winds That May Play Significant Role in Galactic Evolution

Science.gov (United States)

2001-09-01

Colorful star-forming regions that have captivated stargazers since the advent of the telescope 400 years ago contain gas thousands of times more energetic than previously recognized, powered by colliding stellar winds. This multimillion-degree gas radiated as X rays is one of the long-sought sources of energy and elements in the Milky Way galaxy's interstellar medium. A team led by Leisa Townsley, a senior research associate in astronomy and astrophysics at Penn State University, uncovered this wind phenomenon in the Rosette Nebula, a stellar nursery. With the Chandra X-ray Observatory, the team found that the most massive stars in the nebula produce winds that slam into each other, create violent shocks, and infuse the region with 6-million-degree gas. The findings are presented in Washington, D.C., today at a conference entitled "Two Years of Science with Chandra." "A ghostly glow of diffuse X-ray emission pervades the Rosette Nebula and perhaps many other similar star-forming regions throughout the Galaxy," said Townsley. "We now have a new view of the engine lighting the beautiful Rosette Nebula and new evidence for how the interstellar medium may be energized." Townsley and her colleagues created a striking X-ray panorama of the Rosette Molecular Cloud from four images with Chandra's Advanced CCD Imaging Spectrometer. This is a swath of the sky nearly 100 light years across sprayed with hundreds of X-ray-emitting young stars. In one corner of the Rosette Molecular Cloud lies the Rosette Nebula, called an "H II region" because the hydrogen gas there has been stripped of its electrons due to the strong ultraviolet radiation from its young stars. This region, about 5,000 light years away in the constellation Monoceros, the Unicorn, has long been a favorite among amateur astronomers. The wispy, colorful display is visible with small telescopes. The Chandra survey reveals, for the first time, 6-million-degree gas at the center of the Rosette Nebula, occupying a

X-RAY EMISSION FROM MAGNETIC MASSIVE STARS

International Nuclear Information System (INIS)

Nazé, Yaël; Petit, Véronique; Rinbrand, Melanie; Owocki, Stan; Cohen, David; Ud-Doula, Asif; Wade, Gregg A.

2014-01-01

Magnetically confined winds of early-type stars are expected to be sources of bright and hard X-rays. To clarify the systematics of the observed X-ray properties, we have analyzed a large series of Chandra and XMM-Newton observations, corresponding to all available exposures of known massive magnetic stars (over 100 exposures covering ∼60% of stars compiled in the catalog of Petit et al.). We show that the X-ray luminosity is strongly correlated with the stellar wind mass-loss rate, with a power-law form that is slightly steeper than linear for the majority of the less luminous, lower- M-dot B stars and flattens for the more luminous, higher- M-dot O stars. As the winds are radiatively driven, these scalings can be equivalently written as relations with the bolometric luminosity. The observed X-ray luminosities, and their trend with mass-loss rates, are well reproduced by new MHD models, although a few overluminous stars (mostly rapidly rotating objects) exist. No relation is found between other X-ray properties (plasma temperature, absorption) and stellar or magnetic parameters, contrary to expectations (e.g., higher temperature for stronger mass-loss rate). This suggests that the main driver for the plasma properties is different from the main determinant of the X-ray luminosity. Finally, variations of the X-ray hardnesses and luminosities, in phase with the stellar rotation period, are detected for some objects and they suggest that some temperature stratification exists in massive stars' magnetospheres

Chandra-SDSS Normal and Star-Forming Galaxies. I. X-Ray Source Properties of Galaxies Detected by the Chandra X-Ray Observatory in SDSS DR2

Science.gov (United States)

Hornschemeier, A. E.; Heckman, T. M.; Ptak, A. F.; Tremonti, C. A.; Colbert, E. J. M.

2005-01-01

We have cross-correlated X-ray catalogs derived from archival Chandra X-Ray Observatory ACIS observations with a Sloan Digital Sky Survey Data Release 2 (DR2) galaxy catalog to form a sample of 42 serendipitously X-ray-detected galaxies over the redshift interval 0.03X-ray-studied samples of normal galaxies and those in the deepest X-ray surveys. Our chief purpose is to compare optical spectroscopic diagnostics of activity (both star formation and accretion) with X-ray properties of galaxies. Our work supports a normalization value of the X-ray-star formation rate correlation consistent with the lower values published in the literature. The difference is in the allocation of X-ray emission to high-mass X-ray binaries relative to other components, such as hot gas, low-mass X-ray binaries, and/or active galactic nuclei (AGNs). We are able to quantify a few pitfalls in the use of lower resolution, lower signal-to-noise ratio optical spectroscopy to identify X-ray sources (as has necessarily been employed for many X-ray surveys). Notably, we find a few AGNs that likely would have been misidentified as non-AGN sources in higher redshift studies. However, we do not find any X-ray-hard, highly X-ray-luminous galaxies lacking optical spectroscopic diagnostics of AGN activity. Such sources are members of the ``X-ray-bright, optically normal galaxy'' (XBONG) class of AGNs.

Effects of coronal regions on the x-ray flux and ionization conditions in the winds of ob supergiants and of stars

International Nuclear Information System (INIS)

Cassinelli, J.P.; Olson, G.L.

1979-01-01

The anomalously strong O VI and N V lines in O stars and the C IV lines in B supergiants may be due to Auger ionization by X-rays from a thin coronal zone at the base of the cool stellar winds. We determine the size of a corona that is necessary to produce the overall ionization conditions in zeta Pup as has been deduced by Olson from line profile analysis. In the ionization balance calculations we account for diffuse radiation field in the wind and for the large optical depths in the He II continuum due to radiative and Auger ionization edges of abundant elements. The X-ray flux transmitted through the wind is calculated and compared with upper limits derived for upper limits derived for zeta Pup observations from ANS and Uhuru satellites. It is found that a coronal zone with a temperature of 5x10 6 K and a volume emission measure of 10 58 cm -3 can produce the required ionization in a wind having a temperature of 30,000--35,000 K. The emergent X-ray flux bears little resemblance to the coronal emissivity because of the opacity of the wind. The X-ray flux nearly reaches the upper limits derived from the ANS observations and, at several energy bands, should be detectable by the HEAO B satellite. A simplified analysis of the Auger ionization process is developed and applied to other Of and OB supergiants. We find that the model can explain the presence of C IV and Si IV in supergaints with effective temperatures as low as 12,000 K and can explain the appearance of O VI and N V lines in early type supergiants as late as BO.5 and B2, respectively

Hitomi X-ray observation of the pulsar wind nebula G21.5-0.9

Science.gov (United States)

Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; Allen, Steven W.; Angelini, Lorella; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W.; Blandford, Roger; Brenneman, Laura W.; Brown, Gregory V.; Bulbul, Esra; Cackett, Edward M.; Chernyakova, Maria; Chiao, Meng P.; Coppi, Paolo S.; Costantini, Elisa; de Plaa, Jelle; de Vries, Cor P.; den Herder, Jan-Willem; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Enoto, Teruaki; Ezoe, Yuichiro; Fabian, Andrew C.; Ferrigno, Carlo; Foster, Adam R.; Fujimoto, Ryuichi; Fukazawa, Yasushi; Furuzawa, Akihiro; Galeazzi, Massimiliano; Gallo, Luigi C.; Gandhi, Poshak; Giustini, Margherita; Goldwurm, Andrea; Gu, Liyi; Guainazzi, Matteo; Haba, Yoshito; Hagino, Kouichi; Hamaguchi, Kenji; Harrus, Ilana M.; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hayashida, Kiyoshi; Hiraga, Junko S.; Hornschemeier, Ann; Hoshino, Akio; Hughes, John P.; Ichinohe, Yuto; Iizuka, Ryo; Inoue, Hajime; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Iwai, Masachika; Kaastra, Jelle; Kallman, Tim; Kamae, Tsuneyoshi; Kataoka, Jun; Katsuda, Satoru; Kawai, Nobuyuki; Kelley, Richard L.; Kilbourne, Caroline A.; Kitaguchi, Takao; Kitamoto, Shunji; Kitayama, Tetsu; Kohmura, Takayoshi; Kokubun, Motohide; Koyama, Katsuji; Koyama, Shu; Kretschmar, Peter; Krimm, Hans A.; Kubota, Aya; Kunieda, Hideyo; Laurent, Philippe; Lee, Shiu-Hang; Leutenegger, Maurice A.; Limousin, Olivier; Loewenstein, Michael; Long, Knox S.; Lumb, David; Madejski, Greg; Maeda, Yoshitomo; Maier, Daniel; Makishima, Kazuo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian R.; Mehdipour, Missagh; Miller, Eric D.; Miller, Jon M.; Mineshige, Shin; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mizuno, Tsunefumi; Mori, Hideyuki; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard F.; Nakagawa, Takao; Nakajima, Hiroshi; Nakamori, Takeshi; Nakashima, Shinya; Nakazawa, Kazuhiro; Nobukawa, Kumiko K.; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ohashi, Takaya; Ohno, Masanori; Okajima, Takashi; Ota, Naomi; Ozaki, Masanobu; Paerels, Frits; Paltani, Stéphane; Petre, Robert; Pinto, Ciro; Porter, Frederick S.; Pottschmidt, Katja; Reynolds, Christopher S.; Safi-Harb, Samar; Saito, Shinya; Sakai, Kazuhiro; Sasaki, Toru; Sato, Goro; Sato, Kosuke; Sato, Rie; Sawada, Makoto; Schartel, Norbert; Serlemtsos, Peter J.; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall K.; Soong, Yang; Stawarz, Łukasz; Sugawara, Yasuharu; Sugita, Satoshi; Szymkowiak, Andrew; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shin'ichiro; Takei, Yoh; Tamagawa, Toru; Tamura, Takayuki; Tanaka, Takaaki; Tanaka, Yasuo; Tanaka, Yasuyuki T.; Tashiro, Makoto S.; Tawara, Yuzuru; Terada, Yukikatsu; Terashima, Yuichi; Tombesi, Francesco; Tomida, Hiroshi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi Go; Uchida, Hiroyuki; Uchiyama, Hideki; Uchiyama, Yasunobu; Ueda, Shutaro; Ueda, Yoshihiro; Uno, Shin'ichiro; Urry, C. Megan; Ursino, Eugenio; Watanabe, Shin; Werner, Norbert; Wilkins, Dan R.; Williams, Brian J.; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko Y.; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yatsu, Yoichi; Yonetoku, Daisuke; Zhuravleva, Irina; Zoghbi, Abderahmen; Sato, Toshiki; Nakaniwa, Nozomu; Murakami, Hiroaki; Guest, Benson

2018-04-01

We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5-0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8-80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager, and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the PWN itself, we find that the Hitomi spectra can be fitted with a broken power law with photon indices of Γ1 = 1.74 ± 0.02 and Γ2 = 2.14 ± 0.01 below and above the break at 7.1 ± 0.3 keV, which is significantly lower than the NuSTAR result (˜9.0 keV). The spectral break cannot be reproduced by time-dependent particle injection one-zone spectral energy distribution models, which strongly indicates that a more complex emission model is needed, as suggested by recent theoretical models. We also search for narrow emission or absorption lines with the SXS, and perform a timing analysis of PSR J1833-1034 with the HXI and the Soft Gamma-ray Detector. No significant pulsation is found from the pulsar. However, unexpectedly, narrow absorption line features are detected in the SXS data at 4.2345 keV and 9.296 keV with a significance of 3.65 σ. While the origin of these features is not understood, their mere detection opens up a new field of research and was only possible with the high resolution, sensitivity, and ability to measure extended sources provided by an X-ray microcalorimeter.

Variable X-ray sky with Lobster Eye Telescopes

International Nuclear Information System (INIS)

Hudec, R.; Pina, L.; Inneman, A.; Sveda, L.

2004-01-01

The variable X-ray sky requires wide-field monitoring with high sensitivity. We refer on novel X-ray telescopes with high sensitivity as well as large field of view. The results are very promising, allowing the proposals for space projects with very wide-field Lobster-eye X-ray optics to be considered. The novel telescopes will monitor the sky with unprecedented sensitivity and angular resolution of order of 1 arcmin. They are expected to contribute essentially to study and to understand various astrophysical objects such as AGN, SNe, GRBs, X-ray flashes, galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc

Planetary X-ray studies: past, present and future

Science.gov (United States)

Branduardi-Raymont, Graziella

2016-07-01

Our solar system is a fascinating physics laboratory and X-ray observations are now firmly established as a powerful diagnostic tool of the multiple processes taking place in it. The science that X-rays reveal encompasses solar, space plasma and planetary physics, and the response of bodies in the solar system to the impact of the Sun's activity. This talk will review what we know from past observations and what we expect to learn in the short, medium and long term. Observations with Chandra and XMM-Newton have demonstrated that the origin of Jupiter's bright soft X-ray aurorae lies in the Charge eXchange (CX) process, likely to involve the interaction with atmospheric neutrals of local magnetospheric ions, as well as those carried in the solar wind. At higher energies electron bremsstrahlung is thought to be the X-ray emitting mechanism, while the whole planetary disk acts as a mirror for the solar X-ray flux via Thomson and fluorescent scattering. This 'X-ray mirror' phenomenon is all that is observed from Saturn's disk, which otherwise lacks X-ray auroral features. The Earth's X-ray aurora is bright and variable and mostly due to electron bremsstrahlung and line emission from atmospheric species. Un-magnetised planets, Venus and Mars, do not show X-ray aurorae but display the interesting combination of mirroring the solar X-ray flux and producing X-rays by Solar Wind Charge eXchange (SWCX) in their exospheres. These processes respond to different solar stimulation (photons and solar wind plasma respectively) hence their relative contributions are seen to vary according to the Sun's output. Present and future of planetary X-ray studies are very bright. We are preparing for the arrival of the Juno mission at Jupiter this summer and for coordinated observations with Chandra and XMM-Newton on the approach and later during Juno's orbital phase. These will allow direct correlation of the local plasma conditions with the X-ray emissions and the establishment of the

X-ray Measurements of Black Hole X-ray Binary Source GRS 1915+ ...

Indian Academy of Sciences (India)

tribpo

March 30th, 1997 during a quiescent phase of the source. .... The field of view ... tagged with a 25µsec resolution and transmitted to ground on a 40 Kbit PCM/FM ... only composite model fits for the soft and hard X ray band are used and the ...

X-ray emission from comets

International Nuclear Information System (INIS)

Dennerl, Konrad

1999-01-01

When comet Hyakutake (C/1996 B2) encountered Earth in March 1996 at a minimum distance of only 15 million kilometers (40 times the distance of the moon), x-ray and extreme ultraviolet emission was discovered for the first time from a comet. The observations were performed with the astronomy satellites ROSAT and EUVE. A systematic search for x-rays from comets in archival data, obtained during the ROSAT all-sky survey in 1990/91, resulted in the discovery of x-ray emission from four additional comets. They were detected at seven occasions in total, when they were optically 300 to 30 000 times fainter than Hyakutake. These findings indicated that comets represent a new class of celestial x-ray sources. Subsequent detections of x-ray emission from additional comets with the satellites ROSAT, EUVE, and BeppoSAX confirmed this conclusion. The x-ray observations have obviously revealed the presence of a process in comets which had escaped attention until recently. This process is most likely charge exchange between highly charged heavy ions in the solar wind and cometary neutrals. The solar wind, a stream of particles continuously emitted from the sun with ≅ 400 km s -1 , consists predominantly of protons, electrons, and alpha particles, but contains also a small fraction (≅0.1%) of highly charged heavier ions, such as C 6+ ,O 6+ ,Ne 8+ ,Si 9+ ,Fe 11+ . When these ions capture electrons from the cometary gas, they attain highly excited states and radiate a large fraction of their excitation energy in the extreme ultraviolet and x-ray part of the spectrum. Charge exchange reproduces the intensity, the morphology and the spectrum of the observed x-ray emission from comets very well

The First Simultaneous X-Ray/Radio Detection of the First Be/BH System MWC 656

Energy Technology Data Exchange (ETDEWEB)

Ribó, M.; Paredes, J. M.; Marcote, B.; Moldón, J.; Paredes-Fortuny, X. [Departament de Física Quàntica i Astrofísica, Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, IEEC-UB, Martí i Franquès 1, E08028 Barcelona (Spain); Munar-Adrover, P. [INAF/IAPS-Roma, I-00133 Roma (Italy); Iwasawa, K. [ICREA, Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, IEEC-UB, Martí i Franquès 1, E-08028 Barcelona (Spain); Casares, J. [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Migliari, S. [European Space Astronomy Centre, Apartado/P.O. Box 78, Villanueva de la Canada, E-28691 Madrid (Spain)

2017-02-01

MWC 656 is the first known Be/black hole (BH) binary system. Be/BH binaries are important in the context of binary system evolution and sources of detectable gravitational waves because they are possible precursors of coalescing neutron star/BH binaries. X-ray observations conducted in 2013 revealed that MWC 656 is a quiescent high-mass X-ray binary (HMXB), opening the possibility to explore X-ray/radio correlations and the accretion/ejection coupling down to low luminosities for BH HMXBs. Here we report on a deep joint Chandra /VLA observation of MWC 656 (and contemporaneous optical data) conducted in 2015 July that has allowed us to unambiguously identify the X-ray counterpart of the source. The X-ray spectrum can be fitted with a power law with Γ ∼ 2, providing a flux of ≃4 × 10{sup −15} erg cm{sup −2} s{sup −1} in the 0.5–8 keV energy range and a luminosity of L {sub X} ≃ 3 × 10{sup 30} erg s{sup −1} at a 2.6 kpc distance. For a 5 M{sub ⊙} BH this translates into ≃5 × 10{sup −9} L {sub Edd}. These results imply that MWC 656 is about 7 times fainter in X-rays than it was two years before and reaches the faintest X-ray luminosities ever detected in stellar-mass BHs. The radio data provide a detection with a peak flux density of 3.5 ± 1.1 μ Jy beam{sup −1}. The obtained X-ray/radio luminosities for this quiescent BH HMXB are fully compatible with those of the X-ray/radio correlations derived from quiescent BH low-mass X-ray binaries. These results show that the accretion/ejection coupling in stellar-mass BHs is independent of the nature of the donor star.

On the Spatially Resolved Star Formation History in M51. II. X-Ray Binary Population Evolution

Science.gov (United States)

Lehmer, B. D.; Eufrasio, R. T.; Markwardt, L.; Zezas, A.; Basu-Zych, A.; Fragos, T.; Hornschemeier, A. E.; Ptak, A.; Tzanavaris, P.; Yukita, M.

2017-12-01

We present a new technique for empirically calibrating how the X-ray luminosity function (XLF) of X-ray binary (XRB) populations evolves following a star formation event. We first utilize detailed stellar population synthesis modeling of far-UV-to-far-IR photometry of the nearby face-on spiral galaxy M51 to construct maps of the star formation histories (SFHs) on subgalactic (≈400 pc) scales. Next, we use the ≈850 ks cumulative Chandra exposure of M51 to identify and isolate 2-7 keV detected point sources within the galaxy, and we use our SFH maps to recover the local properties of the stellar populations in which each X-ray source is located. We then divide the galaxy into various subregions based on their SFH properties (e.g., star formation rate (SFR) per stellar mass ({M}\\star ) and mass-weighted stellar age) and group the X-ray point sources according to the characteristics of the regions in which they are found. Finally, we construct and fit a parameterized XLF model that quantifies how the XLF shape and normalization evolves as a function of the XRB population age Our best-fit model indicates that the XRB XLF per unit stellar mass declines in normalization, by ˜3-3.5 dex, and steepens in slope from ≈10 Myr to ≈10 Gyr. We find that our technique recovers results from past studies of how XRB XLFs and XRB luminosity scaling relations vary with age and provides a self-consistent picture for how XRB XLFs evolve with age.

MOXE: An X-ray all-sky monitor for Soviet Spectrum-X-Gamma Mission

Science.gov (United States)

Priedhorsky, W.; Fenimore, E. E.; Moss, C. E.; Kelley, R. L.; Holt, S. S.

1989-01-01

A Monitoring Monitoring X-Ray Equipment (MOXE) is being developed for the Soviet Spectrum-X-Gamma Mission. MOXE is an X-ray all-sky monitor based on array of pinhole cameras, to be provided via a collaboration between Goddard Space Flight Center and Los Alamos National Laboratory. The objectives are to alert other observers on Spectrum-X-Gamma and other platforms of interesting transient activity, and to synoptically monitor the X-ray sky and study long-term changes in X-ray binaries. MOXE will be sensitive to sources as faint as 2 milliCrab (5 sigma) in 1 day, and cover the 2 to 20 KeV band.

Where is the X-ray emission coming from in RT Cru Symbiotic System?

Science.gov (United States)

Karovska, Margarita

2014-11-01

RT Cru is a member of a new sub-class of symbiotic interacting binaries with copious hard X-ray emission. It consists of a high-mass WD (>1.3 Ms) accreting from the wind of an M giant, and it is an important system to study in order to constrain precursor conditions for asymmetric PN and SN Ia. The Chandra HRC-I observation (Dec 2012), and an overlapping Swift observation, detected intermittent soft X-ray flaring, and we find evidence for a significant soft component in the spectrum. The flaring could be a consequence of clumped absorption columns moving in and out of the line of sight, or the variations could be due to changes at the accretion boundary layer. Further observations are needed to determine the origin of the soft emission and its relation to the hard emission.

Einstein X-ray observations of M101

International Nuclear Information System (INIS)

Trinchieri, G.; Fabbiano, G.; Romaine, S.

1990-01-01

The Einstein X-ray observations of the face-on spiral galaxy M101 are presented. The global X-ray luminosity L(x) of M101 is about 1.2 x 10 to the 40th ergs/s for D = 7.2 Mpc, consistent with the expected X-ray luminosity of normal spiral galaxies of its optical magnitude. The X-ray emission is mostly due to very luminous individual sources, with L(x) greater than 10 to the 38th ergs/s each, most likely very massive accreting binary systems. The data suggest a deficiency of sources in the luminosity range of L(x) from about 10 to the 37th to about 10 to the 38th ergs/s, which would indicate that the luminosity distribution of the X-ray sources in M101 might be different from that of M31 or M33. 35 refs

Einstein X-ray observations of M101

Science.gov (United States)

Trinchieri, G.; Fabbiano, G.; Romaine, S.

1990-01-01

The Einstein X-ray observations of the face-on spiral galaxy M101 are presented. The global X-ray luminosity L(x) of M101 is about 1.2 x 10 to the 40th ergs/s for D = 7.2 Mpc, consistent with the expected X-ray luminosity of normal spiral galaxies of its optical magnitude. The X-ray emission is mostly due to very luminous individual sources, with L(x) greater than 10 to the 38th ergs/s each, most likely very massive accreting binary systems. The data suggest a deficiency of sources in the luminosity range of L(x) from about 10 to the 37th to about 10 to the 38th ergs/s, which would indicate that the luminosity distribution of the X-ray sources in M101 might be different from that of M31 or M33.

Spinning-Up: the Case of the Symbiotic X-Ray Binary 3A 1954+319

Science.gov (United States)

Fuerst, F.; Marcu, D. M.; Pottschmidt, K.; Grinberg, V.; Wilms, J.; CadolleBel, M.

2011-01-01

We present a timing and spectral analysis of the variable X-ray source 3A 1954+319. Our analysis is mainly based on an outburst serendipitously observed during INTEGRAL Key Program observations of the Cygnus region in 2008 fall and on the Swift/BAT longterm light curve. Previous observations, though sparse, have identified the source to be one of only nine known symbiotic X-ray binaries, i.e., systems composed of an accreting neutron star orbiting in a highly inhomogeneous medium around an M-giant companion. The spectrum of3A 1954+319 above > 20 keV can be best described by a broken power law model. The extremely long pulse period of approx.5.3 hours is clearly visible in the INTEGRAL/ISGRI light curve and confirmed through an epoch folding period search. Furthermore, the light curve allows us to determine a very strong spin up of -2 x 10(exp -4) h/h during the outburst. This spin up is confirmed by the pulse period evolution calculated from Swift/BAT data. The Swift/BAT data also show a long spin-down trend prior to the 2008 outburst, which is confirmed in archival INTEGRAL/ISGRI data. We discuss possible accretion models and geometries allowing for the transfer of such large amounts of angular momentum and investigate the harder spectrum of this outburst compared to previously published results.

X-Ray Emission from an Asymmetric Blast Wave and a Massive White Dwarf in the Gamma Ray Emitting Nova V407 CYG

Science.gov (United States)

Nelson, Thomas; Donato, Davide; Mukai, Koji; Sokoloski, Jennifer; Chomiuk, Laura

2012-01-01

Classical nova events in symbiotic stars, although rare, offer a unique opportunity to probe the interaction between ejecta and a dense environment in stellar explosions. In this work, we use X-ray data obtained with Swift and Suzaku during the recent classical nova outburst in V407 Cyg to explore such an interaction. We find evidence of both equilibrium and non-equilibrium ionization plasmas at the time of peak X-ray brightness, indicating a strong asymmetry in the density of the emitting region. Comparing a simple model to the data, we find that the X-ray evolution is broadly consistent with nova ejecta driving a forward shock into the dense wind of the Mira companion. We detect a highly absorbed soft X-ray component in the spectrum during the first 50 days of the outburst that is consistent with supersoft emission from the nuclear burning white dwarf. The high temperature and short turn off time of this emission component, in addition to the observed breaks in the optical and UV lightcurves, indicate that the white dwarf in the binary is extremely massive. Finally, we explore the connections between the X-ray and GeV-ray evolution, and propose that the gamma ray turn-off is due to the stalling of the forward shock as the ejecta reach the red giant surface.

A soft X-ray image of the Moon

International Nuclear Information System (INIS)

Schmitt, J.H.M.M.; Aschenbach, B.; Hasinger, G.; Pfeffermann, E.; Predehl, P.; Truemper, J.; Snowden, S.L.; Wisconsin Univ., Madison, WI

1991-01-01

A soft X-ray image of the Moon obtained by the Roentgen Observatory Satellite ROSAT clearly shows a sunlit crescent, demonstrating that the Moon's X-ray luminosity arises from backscattering of solar X-rays. The Moon's optically dark side is also X-ray dark, and casts a distinct shadow on the diffuse cosmic X-ray background. Unexpectedly, the dark side seems to emit X-rays at a level about one per cent that of the bright side; this emission very probably results from energetic solar-wind electrons striking the Moon's surface. (author)

Some observational aspects of compact galactic X-ray sources

International Nuclear Information System (INIS)

Heise, J.

1982-01-01

This thesis contains the following observations of compact galactic X-ray sources: i) the X-ray experiments onboard the Astronomical Netherlands Satellite ANS, ii) a rocket-borne ultra soft X-ray experiment and iii) the Objective Grating Spectrometer onboard the EINSTEIN observatory. In Chapter I the various types of compact galactic X-ray sources are reviewed and put into the perspective of earlier and following observations. In Chapter II the author presents some of the observations of high luminosity X-ray sources, made with ANS, including the detection of soft X-rays from the compact X-ray binary Hercules X-1 and the ''return to the high state'' of the black hole candidate Cygnus X-1. Chapter III deals with transient X-ray phenomena. Results on low luminosity galactic X-ray sources are collected in Chapter IV. (Auth.)

Doubly Fed Induction Generator Wind Turbines with Fuzzy Controller: A Survey

Directory of Open Access Journals (Sweden)

J. S. Sathiyanarayanan

2014-01-01

Full Text Available Wind energy is one of the extraordinary sources of renewable energy due to its clean character and free availability. With the increasing wind power penetration, the wind farms are directly influencing the power systems. The majority of wind farms are using variable speed wind turbines equipped with doubly fed induction generators (DFIG due to their advantages over other wind turbine generators (WTGs. Therefore, the analysis of wind power dynamics with the DFIG wind turbines has become a very important research issue, especially during transient faults. This paper presents fuzzy logic control of doubly fed induction generator (DFIG wind turbine in a sample power system. Fuzzy logic controller is applied to rotor side converter for active power control and voltage regulation of wind turbine.

Doubly fed induction generator wind turbines with fuzzy controller: a survey.

Science.gov (United States)

Sathiyanarayanan, J S; Kumar, A Senthil

2014-01-01

Wind energy is one of the extraordinary sources of renewable energy due to its clean character and free availability. With the increasing wind power penetration, the wind farms are directly influencing the power systems. The majority of wind farms are using variable speed wind turbines equipped with doubly fed induction generators (DFIG) due to their advantages over other wind turbine generators (WTGs). Therefore, the analysis of wind power dynamics with the DFIG wind turbines has become a very important research issue, especially during transient faults. This paper presents fuzzy logic control of doubly fed induction generator (DFIG) wind turbine in a sample power system. Fuzzy logic controller is applied to rotor side converter for active power control and voltage regulation of wind turbine.

Observation of hard X-rays line emission from Her X-1

Energy Technology Data Exchange (ETDEWEB)

Polcaro, V.F.; Bazzano, A.; la Padula, C.; Ubertini, P.; Vialetto, G.; Manchanda, R.K.; Damle, S.V.

1982-04-01

We present the results of a hard X-ray measurement of the binary source Her X-1, carried out with a balloon borne X-ray telescope consisting of two Multiwire Proportional Counters, having 900 cm/sup 2/ sensitive area each and spectral resolution of 15% and 24% FWHM respectively at 60 keV. The source was observed during the 'Mid-on' state. Our data confirm the previously reported high energy emission line overimposed on the low energy thermal spectrum.

Partial Accretion in the Propeller Stage of Low-mass X-Ray Binary Aql X–1

International Nuclear Information System (INIS)

Güngör, C.; Ekşi, K. Y.; Göğüş, E.; Güver, T.

2017-01-01

Aql X–1 is one of the most prolific low-mass X-ray binary transients (LMXBTs) showing outbursts almost annually. We present the results of our spectral analyses of Rossi X-Ray Timing Explorer /proportional counter-array observations of the 2000 and 2011 outbursts. We investigate the spectral changes related to the changing disk-magnetosphere interaction modes of Aql X–1. The X-ray light curves of the outbursts of LMXBTs typically show phases of fast rise and exponential decay. The decay phase shows a “knee” where the flux goes from the slow-decay to the rapid-decay stage. We assume that the rapid decay corresponds to a weak propeller stage at which a fraction of the inflowing matter in the disk accretes onto the star. We introduce a novel method for inferring, from the light curve, the fraction of the inflowing matter in the disk that accretes onto the neutron star depending on the fastness parameter. We determine the fastness parameter range within which the transition from the accretion to the partial propeller stage is realized. This fastness parameter range is a measure of the scale height of the disk in units of the inner disk radius. We applied the method to a sample of outbursts of Aql X–1 with different maximum flux and duration times. We show that different outbursts with different maximum luminosity and duration follow a similar path in the parameter space of accreted/inflowing mass flux fraction versus fastness parameter.

Partial Accretion in the Propeller Stage of Low-mass X-Ray Binary Aql X–1

Energy Technology Data Exchange (ETDEWEB)

Güngör, C.; Ekşi, K. Y. [İstanbul Technical University, Faculty of Science and Letters, Physics Engineering Department, 34469, İstanbul (Turkey); Göğüş, E. [Sabancı University, Faculty of Engineering and Natural Science, Orhanlı—Tuzla, 34956, İstanbul (Turkey); Güver, T., E-mail: gungorcan@itu.edu.tr [İstanbul University, Science Faculty, Department of Astronomy and Space Sciences, Beyazıt, 34119, İstanbul (Turkey)

2017-10-10

Aql X–1 is one of the most prolific low-mass X-ray binary transients (LMXBTs) showing outbursts almost annually. We present the results of our spectral analyses of Rossi X-Ray Timing Explorer /proportional counter-array observations of the 2000 and 2011 outbursts. We investigate the spectral changes related to the changing disk-magnetosphere interaction modes of Aql X–1. The X-ray light curves of the outbursts of LMXBTs typically show phases of fast rise and exponential decay. The decay phase shows a “knee” where the flux goes from the slow-decay to the rapid-decay stage. We assume that the rapid decay corresponds to a weak propeller stage at which a fraction of the inflowing matter in the disk accretes onto the star. We introduce a novel method for inferring, from the light curve, the fraction of the inflowing matter in the disk that accretes onto the neutron star depending on the fastness parameter. We determine the fastness parameter range within which the transition from the accretion to the partial propeller stage is realized. This fastness parameter range is a measure of the scale height of the disk in units of the inner disk radius. We applied the method to a sample of outbursts of Aql X–1 with different maximum flux and duration times. We show that different outbursts with different maximum luminosity and duration follow a similar path in the parameter space of accreted/inflowing mass flux fraction versus fastness parameter.

Observations of EUV and X-ray Emission from Comets

Science.gov (United States)

Lisse, C.

The unexpected discovery of x-ray emission from Comet Hyakutake in March 1996 (Lisse et al. 1996) produced a number of questions about the physical mechanism producing the radiation. The original detection and subsequent observations have shown that the very soft (best fit thermal bremsstrahlung model kT0.2 keV) emission is due to an interaction between the solar wind and the comet's atmosphere. Using the results from the more than 15 comets detected to date in x-rays, I report here on the latest results on cometary x-ray emission, including new results from Chandra, and show that charge exchange between highly ionized minor ions in the solar wind and neutral gases in the cometary coma is the most likely operative mechanism. I then use this result to study a number of problems of astrophysical interest: the nature of the cometary coma, other possible sources of x-ray emission in the solar system, the structure of the solar wind in the heliosphere, and the source of the local x-ray background.

Crowbar System in Doubly Fed Induction Wind Generators

Directory of Open Access Journals (Sweden)

Maurício B. C. Salles

2010-04-01

Full Text Available In the last 15 years, the use of doubly fed induction machines in modern variable-speed wind turbines has increased rapidly. This development has been driven by the cost reduction as well as the low-loss generation of Insulated Gate Bipolar Transistors (IGBT. According to new grid code requirements, wind turbines must remain connected to the grid during grid disturbances. Moreover, they must also contribute to voltage support during and after grid faults. The crowbar system is essential to avoid the disconnection of the doubly fed induction wind generators from the network during faults. The insertion of the crowbar in the rotor circuits for a short period of time enables a more efficient terminal voltage control. As a general rule, the activation and the deactivation of the crowbar system is based only on the DC-link voltage level of the back-to-back converters. In this context, the authors discuss the critical rotor speed to analyze the instability of doubly fed induction generators during grid faults.

XMM-Newton Detection of Hard X-Ray Emission in the Nitrogen-Type Wolf-Rayet Star WR 110

Science.gov (United States)

Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel; Schmutz, Werner

2002-06-01

We have used the excellent sensitivity of XMM-Newton to obtain the first high-quality X-ray spectrum of a Wolf-Rayet (W-R) star that is not known to be a member of a binary system. Our target, the nitrogen-type star WR 110 (HD 165688), was also observed and detected with the Very Large Array at four different frequencies. The radio flux density increases with frequency according to a power law Sν~ν+0.64+/-0.10, in very good agreement with the behavior expected for free-free wind emission. The radio data give an ionized mass-loss rate M=4.9×10-5 Msolar yr-1 for an assumed spherical constant-velocity wind. The undispersed CCD X-ray spectra reveal strong emission lines from He-like ions of Mg, Si, and S. The emission measure distribution shows a dominant contribution from cool plasma with a characteristic temperature kTcool~0.5 keV (~6 MK). Little or no excess absorption of this cool component above the value expected from the visual extinction is present. We conclude that the bulk of the cool plasma detected by XMM-Newton lies at hundreds of stellar radii or more if the wind is approximately spherical and homogeneous, but it could lie closer to the star if the wind is clumped. If the cool plasma is due to instability-driven wind shocks, then typical shock velocities are vs~340-550 km s-1 and the average filling factor of X-ray-emitting gas in the wind is no larger than f~10-6. A surprising result is the unambiguous detection of a hard X-ray component that is clearly seen in the hard-band images and the spectra. This hard component accounts for about half of the observed flux and can be acceptably fitted by a hot, optically thin thermal plasma or a power-law model. If the emission is thermal, then a temperature kThot>=3 keV is derived. Such high temperatures are not predicted by current instability-driven wind shock models, and a different mechanism is thus required to explain the hard X-rays. We examine several possible mechanisms and show that the hard emission

Identifying Bright X-Ray Beasts

Science.gov (United States)

Kohler, Susanna

2017-10-01

Ultraluminous X-ray sources (ULXs) are astronomical sources of X-rays that, while dimmer than active galactic nuclei, are nonetheless brighter than any known stellar process. What are these beasts and why do they shine so brightly?Exceeding the LimitFirst discovered in the 1980s, ULXs are rare sources that have nonetheless been found in all types of galaxies. Though the bright X-ray radiation seems likely to be coming from compact objects accreting gas, theres a problem with this theory: ULXs outshine the Eddington luminosity for stellar-mass compact objects. This means that a stellar-mass object couldnt emit this much radiation isotropically without blowing itself apart.There are two alternative explanations commonly proposed for ULXs:Rather than being accreting stellar-mass compact objects, they are accreting intermediate-mass black holes. A hypothetical black hole of 100 solar masses or more would have a much higher Eddington luminosity than a stellar-mass black hole, making the luminosities that we observe from ULXs feasible.An example of one of the common routes the authors find for a binary system to become a ULX. In this case, the binary begins as two main sequence stars. As one star evolves off the main sequence, the binary undergoes a common envelope phase and a stage of mass transfer. The star ends its life as a supernova, and the resulting neutron star then accretes matter from the main sequence star as a ULX. [Wiktorowicz et al. 2017]They are ordinary X-ray binaries (a stellar-mass compact object accreting matter from a companion star), but they are undergoing a short phase of extreme accretion. During this time, their emission is beamed into jets, making them appear brighter than the Eddington luminosity.Clues from a New DiscoveryA few years ago, a new discovery shed some light on ULXs: M82 X-2, a pulsing ULX. Two more pulsing ULXs have been discovered since then, demonstrating that at least some ULXs contain pulsars i.e., neutron stars as the

Impact of Cosmic-Ray Transport on Galactic Winds

Science.gov (United States)

Farber, R.; Ruszkowski, M.; Yang, H.-Y. K.; Zweibel, E. G.

2018-04-01

The role of cosmic rays generated by supernovae and young stars has very recently begun to receive significant attention in studies of galaxy formation and evolution due to the realization that cosmic rays can efficiently accelerate galactic winds. Microscopic cosmic-ray transport processes are fundamental for determining the efficiency of cosmic-ray wind driving. Previous studies modeled cosmic-ray transport either via a constant diffusion coefficient or via streaming proportional to the Alfvén speed. However, in predominantly cold, neutral gas, cosmic rays can propagate faster than in the ionized medium, and the effective transport can be substantially larger; i.e., cosmic rays can decouple from the gas. We perform three-dimensional magnetohydrodynamical simulations of patches of galactic disks including the effects of cosmic rays. Our simulations include the decoupling of cosmic rays in the cold, neutral interstellar medium. We find that, compared to the ordinary diffusive cosmic-ray transport case, accounting for the decoupling leads to significantly different wind properties, such as the gas density and temperature, significantly broader spatial distribution of cosmic rays, and higher wind speed. These results have implications for X-ray, γ-ray, and radio emission, and for the magnetization and pollution of the circumgalactic medium by cosmic rays.

Time-dependent search for neutrino emission from X-ray binaries with the ANTARES telescope

Energy Technology Data Exchange (ETDEWEB)

Albert, A. [GRPHE—Université de Haute Alsace—Institut universitaire de technologie de Colmar, 34 rue du Grillenbreit, BP 50568, Colmar, 68008 France (France); André, M. [Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposició, Vilanova i la Geltrú, Barcelona, 08800 Spain (Spain); Anton, G. [Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, Erlangen, 91058 Germany (Germany); Ardid, M. [Institut d' Investigació per a la Gestió Integrada de les Zones Costaneres (IGIC), Universitat Politècnica de València, C/ Paranimf 1, Gandia, 46730 Spain (Spain); Aubert, J.-J. [Aix-Marseille Université, CNRS/IN2P3, CPPM UMR 7346, Marseille, 13288 France (France); Avgitas, T.; Baret, B. [APC, Université Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, Paris, 75205 France (France); Barrios-Martí, J., E-mail: antares.spokesperson@in2p3.fr [IFIC—Instituto de Física Corpuscular (CSIC—Universitat de València), c/ Catedrático José Beltrán, 2, Paterna, Valencia, E-46980 Spain (Spain); and others

2017-04-01

ANTARES is currently the largest neutrino telescope operating in the Northern Hemisphere, aiming at the detection of high-energy neutrinos from astrophysical sources. Neutrino telescopes constantly monitor at least one complete hemisphere of the sky, and are thus well-suited to detect neutrinos produced in transient astrophysical sources. A time-dependent search has been applied to a list of 33 X-ray binaries undergoing high flaring activities in satellite data (RXTE/ASM, MAXI and Swift/BAT) and during hardness transition states in the 2008–2012 period. The background originating from interactions of charged cosmic rays in the Earth's atmosphere is drastically reduced by requiring a directional and temporal coincidence with astrophysical phenomena. The results of this search are presented together with comparisons between the neutrino flux upper limits and the neutrino flux predictions from astrophysical models. The neutrino flux upper limits resulting from this search limit the jet parameter space for some astrophysical models.

Discovery of the third transient X-ray binary in the galactic globular cluster Terzan 5

Energy Technology Data Exchange (ETDEWEB)

Bahramian, Arash; Heinke, Craig O.; Sivakoff, Gregory R.; Gladstone, Jeanette C. [Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB T6G 2E1 (Canada); Altamirano, Diego; Wijnands, Rudy [Astronomical Institute " Anton Pannekoek," University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Homan, Jeroen [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States); Linares, Manuel [Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain); Pooley, David [Department of Physics, Sam Houston State University, Huntsville, TX 77341 (United States); Degenaar, Nathalie, E-mail: bahramia@ualberta.ca [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)

2014-01-10

We report and study the outburst of a new transient X-ray binary (XRB) in Terzan 5, the third detected in this globular cluster, Swift J174805.3-244637 or Terzan 5 X-3. We find clear spectral hardening in Swift/XRT data during the outburst rise to the hard state, thanks to our early coverage (starting at L{sub X} ∼ 4 × 10{sup 34} erg s{sup –1}) of the outburst. This hardening appears to be due to the decline in relative strength of a soft thermal component from the surface of the neutron star (NS) during the rise. We identify a Type I X-ray burst in Swift/XRT data with a long (16 s) decay time, indicative of hydrogen burning on the surface of the NS. We use Swift/BAT, MAXI/GSC, Chandra/ACIS, and Swift/XRT data to study the spectral changes during the outburst, identifying a clear hard-to-soft state transition. We use a Chandra/ACIS observation during outburst to identify the transient's position. Seven archival Chandra/ACIS observations show evidence for variations in Terzan 5 X-3's nonthermal component but not the thermal component during quiescence. The inferred long-term time-averaged mass accretion rate, from the quiescent thermal luminosity, suggests that if this outburst is typical and only slow cooling processes are active in the NS core, such outbursts should recur every ∼10 yr.

First light - II. Emission line extinction, population III stars, and X-ray binaries

Science.gov (United States)

Barrow, Kirk S. S.; Wise, John H.; Aykutalp, Aycin; O'Shea, Brian W.; Norman, Michael L.; Xu, Hao

2018-02-01

We produce synthetic spectra and observations for metal-free stellar populations and high-mass X-ray binaries in the Renaissance Simulations at a redshift of 15. We extend our methodology from the first paper in the series by modelling the production and extinction of emission lines throughout a dusty and metal-enriched interstellar and circum-galactic media extracted from the simulation, using a Monte Carlo calculation. To capture the impact of high-energy photons, we include all frequencies from hard X-ray to far-infrared with enough frequency resolution to discern line emission and absorption profiles. The most common lines in our sample in order of their rate of occurrence are Ly α, the C IV λλ1548, 1551 doublet, H α, and the Ca II λλλ8498, 8542, 8662 triplet. The best scenario for a direct observation of a metal-free stellar population is a merger between two Population III Galaxies. In mergers between metal-enriched and metal-free stellar populations, some characteristics may be inferred indirectly. Single Population III galaxies are too dim to be observed photometrically at z = 15. Ly α emission is discernible by JWST as an increase in J200w - J277w colour off the intrinsic stellar tracks. Observations of metal-free stars will be difficult, though not impossible, with the next generation of space telescopes.

Black hole and neutron star soft X-ray transients: a hard X-ray view of their outbursts

International Nuclear Information System (INIS)

Yu, W.

2004-01-01

The RXTE public observations of the outbursts of black hole soft X-ray transients XTE J1550-564, XTE J1859+226, 4U 1630-47, XTE J1118+480, XTE J1650-500, and the neutron star soft X-ray transients 4U 1608-52, Aquila X-1, including a variable 'persistent' neutron star low mass X-ray binary 4U 1705-44, are summarized in this paper. The hard X-ray view of those outbursts, which is quite different from that of the soft X-ray band, suggests that there are several types of outbursts which result in different hard X-ray outburst profile - the outburst profiles are energy dependent. One type is the low/hard state outbursts, the other type is the outburst showing transitions from the low/hard state to the high/soft state, or to the intermediate or to the very high state. The later has an initial low/hard state, introducing the phenomena that the hard X-ray precedes the soft X-ray in the outburst rise. Such outbursts in XTE J1550-564, Aql X-1 and 4U 1705-44 support a two-accretion-flow model which involves one Keplerian disk flow and one sub-Keplerian flow for the initial outburst rise

Measuring the Dust Grains and Distance to X Persei Via Its X-ray Halo

Science.gov (United States)

Smith, Randall

2006-09-01

We propose to observe the X-ray halo of the high mass X-ray binary pulsar X Per to measure interstellar dust grains along the line of sight (LOS) and to determine the distance to X Per. The X-ray halo is formed by scattering from grains along the LOS, which for X Per appear to be concentrated in one molecular cloud. Unlike many other X-ray halo observations, this low-absorption high-latitude sightline is well-characterized from absorption spectroscopy done with HST, Copernicus, and FUSE. This halo observation will measure the distance to the cloud and the dust size distribution in it. We will also be able to determine the distance to X Per by measuring the time delayed pulses in the X-ray halo.

On the spin period distribution in Be/X-ray binaries

Energy Technology Data Exchange (ETDEWEB)

Cheng, Z.-Q.; Shao, Y.; Li, X.-D., E-mail: lixd@nju.edu.cn [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

2014-05-10

There is a remarkable correlation between the spin periods of the accreting neutron stars (NSs) in Be/X-ray binaries (BeXBs) and their orbital periods. Recently, Knigge et al. showed that the distribution of the spin periods contains two distinct subpopulations peaked at ∼10 s and ∼200 s, respectively, and suggested that they may be related to two types of supernovae for the formation of the NSs, i.e., core-collapse and electron-capture supernovae. Here we propose that the bimodal spin period distribution is likely to be ascribed to different accretion modes of the NSs in BeXBs. When the NS tends to capture material from the warped, outer part of the Be star disk and experiences giant outbursts, a radiatively cooling dominated disk is formed around the NS, which spins up the NS and is responsible for the short-period subpopulation. In BeXBs that are dominated by normal outbursts or are persistent, the accretion flow is advection-dominated or quasi-spherical. The spin-up process is accordingly inefficient, leading to longer periods of the neuron stars. The potential relation between the subpopulations and the supernova mechanism is also discussed.

Simulating three-dimensional nonthermal high-energy photon emission in colliding-wind binaries

Energy Technology Data Exchange (ETDEWEB)

Reitberger, K.; Kissmann, R.; Reimer, A.; Reimer, O., E-mail: klaus.reitberger@uibk.ac.at [Institut für Astro- und Teilchenphysik and Institut für Theoretische Physik, Leopold-Franzens-Universität Innsbruck, A-6020 Innsbruck (Austria)

2014-07-01

Massive stars in binary systems have long been regarded as potential sources of high-energy γ rays. The emission is principally thought to arise in the region where the stellar winds collide and accelerate relativistic particles which subsequently emit γ rays. On the basis of a three-dimensional distribution function of high-energy particles in the wind collision region—as obtained by a numerical hydrodynamics and particle transport model—we present the computation of the three-dimensional nonthermal photon emission for a given line of sight. Anisotropic inverse Compton emission is modeled using the target radiation field of both stars. Photons from relativistic bremsstrahlung and neutral pion decay are computed on the basis of local wind plasma densities. We also consider photon-photon opacity effects due to the dense radiation fields of the stars. Results are shown for different stellar separations of a given binary system comprising of a B star and a Wolf-Rayet star. The influence of orbital orientation with respect to the line of sight is also studied by using different orbital viewing angles. For the chosen electron-proton injection ratio of 10{sup –2}, we present the ensuing photon emission in terms of two-dimensional projections maps, spectral energy distributions, and integrated photon flux values in various energy bands. Here, we find a transition from hadron-dominated to lepton-dominated high-energy emission with increasing stellar separations. In addition, we confirm findings from previous analytic modeling that the spectral energy distribution varies significantly with orbital orientation.

The X-Ray Evolution of the Symbiotic Star V407 Cyg During its 2010 Outburst

Directory of Open Access Journals (Sweden)

Mukai K.

2012-06-01

Full Text Available We present a summary of Swift and Suzaku X-ray observations of the 2010 nova outburst of the symbiotic star, V407 Cyg. the Suzaku spectrum obtained on day 30 indicates the presence of the supersoft component from the white dwarf surface, as well as optically thin component from the shock between the nova ejecta and the Mira wind. the Swift observations then allow us to track the evolution of both components from day 4 to day 150. Most notable is the sudden brightening of the optically thin component around day 20. We identify this as the time when the blast wave reached the immediate vicinity of the photosphere of the Mira. We have developed a simpe model of the blast wave - wind interaction that can reproduce the gross features of the X-ray evolution of V407 Cyg. If the model is correct, the binary separation is likely to be larger than previously suggested and the mass-loss rate of the Mira is likely to be relatively low.

A Catalog of Candidate Intermediate-Luminosity X-Ray Objects

Science.gov (United States)

Colbert, E. J. M.; Ptak, A. F.

2002-11-01

ROSAT, and now Chandra, X-ray images allow studies of extranuclear X-ray point sources in galaxies other than our own. X-ray observations of normal galaxies with ROSAT and Chandra have revealed that off-nuclear, compact, intermediate-luminosity (LX[2-10keV]>=1039.0 ergs s-1) X-ray objects (IXOs, a.k.a. ULXs [ultraluminous X-ray sources]) are quite common. Here we present a catalog and finding charts for 87 IXOs in 54 galaxies, derived from all of the ROSAT HRI imaging data for galaxies with cz<=5000 km s-1 from the Third Reference Catalog of Bright Galaxies. We have defined the cutoff LX for IXOs so that it is well above the Eddington luminosity of a 1.4 Msolar black hole (1038.3 ergs s-1), so as not to confuse IXOs with ``normal'' black hole X-ray binaries. This catalog is intended to provide a baseline for follow-up work with Chandra and XMM-Newton, and with space- and ground-based survey work at wavelengths other than X-ray. We demonstrate that elliptical galaxies with IXOs have a larger number of IXOs per galaxy than nonelliptical galaxies with IXOs and note that they are not likely to be merely high-mass X-ray binaries with beamed X-ray emission, as may be the case for IXOs in starburst galaxies. Approximately half of the IXOs with multiple observations show X-ray variability, and many (19) of the IXOs have faint optical counterparts in DSS optical B-band images. Follow-up observations of these objects should be helpful in identifying their nature.

Maximum Wind Power Tracking of Doubly Fed Wind Turbine System Based on Adaptive Gain Second-Order Sliding Mode

Directory of Open Access Journals (Sweden)

Hongchang Sun

2018-01-01

Full Text Available This paper proposes an adaptive gain second-order sliding mode control strategy to track optimal electromagnetic torque and regulate reactive power of doubly fed wind turbine system. Firstly, wind turbine aerodynamic characteristics and doubly fed induction generator (DFIG modeling are presented. Then, electromagnetic torque error and reactive power error are chosen as sliding variables, and fixed gain super-twisting sliding mode control scheme is designed. Considering that uncertainty upper bound is unknown and is hard to be estimated in actual doubly fed wind turbine system, a gain scheduled law is proposed to compel control parameters variation according to uncertainty upper bound real-time. Adaptive gain second-order sliding mode rotor voltage control method is constructed in detail and finite time stability of doubly fed wind turbine control system is strictly proved. The superiority and robustness of the proposed control scheme are finally evaluated on a 1.5 MW DFIG wind turbine system.

X-ray visualization of a mosquito's head

International Nuclear Information System (INIS)

Kikuchi, Kenji; Mochizuki, Osamu

2007-01-01

A technology to visualize an internal anatomy of living animals has developed for a medical diagnostics and biology by using Synchrotron x-ray produced in a Photon Factory. A dynamic motion of organ, muscles and respiratory of small insects is difficult to observe by using conventional x-ray imaging because of luck of special and temporal resolution. We visualized motions of pumps located in a mosquito's head through a Phase-contrast X-ray imaging technique by using a synchrotron X-ray. Isovue370 was fed with a 10% dilute glucose solution to visualize a flow. We found that the phase difference between the motions of an oral cavity pump and pharynx pump was 180 degrees. (author)

Next generation x-ray all-sky monitor

International Nuclear Information System (INIS)

Priedhorsky, W. C.; Peele, A. G.; Nugent, K. A.

1997-01-01

We set forth a conceptual design for x-ray all-sky monitor based on lobster-eye wide-field telescopes. This instrument, suitable for a small satellite, would monitor the flux of objects as faint as 2x10 -15 W/m 2 (0.5-2.4 keV) on a daily basis with a signal-to-noise of 5. Sources would be located to 1-2 arc-minutes. Detailed simulations show that crosstalk from the cruciform lobster images would not significantly compromise performance. At this sensitivity limit, we could monitor not just x-ray binaries but fainter classes of x-ray sources. Hundreds of active galactic nuclei, coronal sources, and cataclysmic variables could be tracked on a daily basis. Large numbers of fast transients should be visible, including gamma-ray bursts and the soft x-ray breakout of nearby type II supernovae. Long-term x-ray measurements will advance our understanding of the geometries and perhaps masses of AGN, and coronal energy sources in stars

DISCOVERY OF PSR J1227−4853: A TRANSITION FROM A LOW-MASS X-RAY BINARY TO A REDBACK MILLISECOND PULSAR

Energy Technology Data Exchange (ETDEWEB)

Roy, Jayanta; Bhattacharyya, Bhaswati; Stappers, Ben [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, M13 9PL (United Kingdom); Ray, Paul S.; Wolff, Michael; Wood, Kent S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Chengalur, Jayaram N. [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411 007 (India); Deneva, Julia [NRC Research Associate, resident at Naval Research Laboratory, Washington, DC 20375-5352 (United States); Camilo, Fernando [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Johnson, Tyrel J. [College of Science, George Mason University, Fairfax, VA 22030, USA, resident at Naval Research Laboratory, Washington, DC 20375 (United States); Hessels, Jason W. T.; Bassa, Cees G. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Keane, Evan F. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Mail H30, P.O. Box 218, VIC 3122 (Australia); Ferrara, Elizabeth C.; Harding, Alice K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2015-02-10

XSS J12270−4859 is an X-ray binary associated with the Fermi Large Area Telescope gamma-ray source 1FGL J1227.9−4852. In 2012 December, this source underwent a transition where the X-ray and optical luminosity dropped and the spectral signatures of an accretion disk disappeared. We report the discovery of a 1.69 millisecond pulsar (MSP), PSR J1227−4853, at a dispersion measure of 43.4 pc cm{sup −3} associated with this source, using the Giant Metrewave Radio Telescope (GMRT) at 607 MHz. This demonstrates that, post-transition, the system hosts an active radio MSP. This is the third system after PSR J1023+0038 and PSR J1824−2452I showing evidence of state switching between radio MSP and low-mass X-ray binary states. We report timing observations of PSR J1227−4853 with the GMRT and Parkes, which give a precise determination of the rotational and orbital parameters of the system. The companion mass measurement of 0.17–0.46 M{sub ⊙} suggests that this is a redback system. PSR J1227−4853 is eclipsed for about 40% of its orbit at 607 MHz with additional short-duration eclipses at all orbital phases. We also find that the pulsar is very energetic, with a spin-down luminosity of ∼10{sup 35} erg s{sup −1}. We report simultaneous imaging and timing observations with the GMRT, which suggests that eclipses are caused by absorption rather than dispersion smearing or scattering.

A study of the reactivity of elemental Cr/Se/Te thin multilayers using X-ray reflectometry, in situ X-ray diffraction and X-ray absorption spectroscopy

International Nuclear Information System (INIS)

Behrens, Malte; Tomforde, Jan; May, Enno; Kiebach, Ragnar; Bensch, Wolfgang; Haeussler, Dietrich; Jaeger, Wolfgang

2006-01-01

The reactivity of [Cr/Se/Te] multilayers under annealing was investigated using X-ray reflectometry, in situ X-ray diffraction, X-ray absorption fine structure (XAFS) measurements and transmission electron microscopy. For all samples, interdiffusion was complete at temperatures between 100 and 300 deg. C, depending on the repeating tri-layer thickness. A crystalline phase nucleated approximately 20 deg. C above the temperature where interdiffusion was finished. The first crystalline phase in a binary Cr/Te sample was layered CrTe 3 nucleating at 230 deg. C. In ternary samples (Se:Te=0.6-1.2), the low-temperature nucleation of such a layered CrQ 3 (Q=Se, Te) phase is suppressed and instead the phase Cr 2 Q 3 nucleates first. Interestingly, this phase decomposes around 500 deg. C into layered CrQ 3 . In contrast, binary Cr/Se samples form stable amorphous alloys after interdiffusion and Cr 3 Se 4 nucleates around 500 deg. C as the only crystalline phase. Evaluation of the XAFS data of annealed samples yield Se-Cr distances of 2.568(1) and 2.552(1) A for Cr 2 Q 3 and CrQ 3 , respectively. In the latter sample, higher coordination shells around Se are seen accounting for the Se-Te contacts in the structure. - Graphical abstract: The first step of the reaction of elemental Cr/Te/Se-multilayers is the interdiffusion of the elements as evidenced by the decay of the modulation peaks in the low-angle region of the X-ray diffraction patterns. The subsequent growth of Bragg peaks at higher scattering angles indicates crystallization of chromium chalcogenide Cr 2 Te 3- x Se x

Binary population synthesis study of the supersoft X-ray phase of single degenerate type Ia supernova progenitors

International Nuclear Information System (INIS)

Meng Xiangcun; Yang Wuming

2011-01-01

In the single degenerate (SD) scenario for type Ia supernovae (SNe Ia), a mass-accreting white dwarf is expected to experience a supersoft X-ray source (SSS) phase. However, some recent observations showed that the expected number of mass-accreting WDs is much lower than that predicted from theory, regardless of whether they are in spiral or elliptical galaxies. In this paper, we performed a binary population synthesis study on the relative duration of the SSS phase to their whole mass-increasing phase of WDs leading to SNe Ia. We found that for about 40% of the progenitor systems, the relative duration is shorter than 2% and the evolution of the mean relative duration shows that it is always smaller than 5%, both for young and old SNe Ia. In addition, before the SNe Ia explosions, more than 55% of the progenitor systems were experiencing a dwarf novae phase and no more than 10% were staying in the SSS phase. These results are consistent with the recent observations and imply that both in early- and late-type galaxies, only a small fraction of mass-accreting WDs resulting in SNe Ia contributes to the supersoft X-ray flux. So, although our results are not directly related to the X-ray output of the SN Ia progenitor, the low supersoft X-ray luminosity observed in early type galaxies may not be able to exclude the validity of the SD model. On the contrary, it is evidence to support the SD scenario.

Dissecting Diffuse X-ray Emission in 30 Doradus with T-ReX

Science.gov (United States)

Townsley, Leisa K.; Broos, Patrick

2017-08-01

30 Doradus (the Tarantula Nebula) offers us a microscope on starburst astrophysics, having endured 25 Myrs of the birth and death of the most massive stars known. Across 30 Dor's 250-pc extent, stellar winds and supernovae have carved its ISM into an amazing display of arcs, pillars, and bubbles. For over 40 years, we have also known that 30 Dor is a bright X-ray emitter, so its familiar stars and cold ISM structures suffer irradiation by multi-million-degree plasmas. The 2-Ms Chandra X-ray Visionary Project ``The Tarantula -- Revealed by X-rays'' (T-ReX) exploits Chandra's fine spatial resolution and the ACIS-I field of view to study ISM interfaces on 1--10 pc scales across the entire 30 Dor complex. Here we give preliminary results from ongoing analyses of these data, focusing on the diffuse X-ray emission. Massive star winds and cavity supernovae over the millenia have contributed to a broad mix of X-ray-emitting plasmas and absorbing columns, showing that 30 Dor's hot ISM is just as complex and confusing as that seen at colder temperatures.

Revealing the nature of the ULX and X-ray population of the spiral galaxy NGC 4088

Energy Technology Data Exchange (ETDEWEB)

Mezcua, M. [Instituto de Astrofísica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Fabbiano, G. [Harvard-Smithsonian Center for Astrophysics (CfA), 60 Garden Street, Cambridge, MA 02138 (United States); Gladstone, J. C. [Department of Physics, University of Alberta, 11322-89 Avenue, Edmonton, Alberta T6G 2G7 (Canada); Farrell, S. A. [Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006 (Australia); Soria, R., E-mail: mmezcua@iac.es [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia)

2014-04-20

We present the first Chandra and Swift X-ray study of the spiral galaxy NGC 4088 and its ultraluminous X-ray source (ULX N4088-X1). We also report very long baseline interferometry (VLBI) observations at 1.6 and 5 GHz performed quasi-simultaneously with the Swift and Chandra observations, respectively. Fifteen X-ray sources are detected by Chandra within the D25 ellipse of NGC 4088, from which we derive the X-ray luminosity function (XLF) of this galaxy. We find the XLF is very similar to those of star-forming galaxies and estimate a star-formation rate of 4.5 M {sub ☉} yr{sup –1}. The Chandra detection of the ULX yields its most accurate X-ray position, which is spatially coincident with compact radio emission at 1.6 GHz. The ULX Chandra X-ray luminosity, L {sub 0.2-10.0} {sub keV} = 3.4 × 10{sup 39} erg s{sup –1}, indicates that N4088-X1 could be located at the high-luminosity end of the high-mass X-ray binary (HMXB) population of NGC 4088. The estimates of the black hole (BH) mass and ratio of radio to X-ray luminosity of N4088-X1 rule out a supermassive BH nature. The Swift X-ray spectrum of N4088-X1 is best described by a thermal Comptonization model and presents a statistically significant high-energy cutoff. We conclude that N4088-X1 is most likely a stellar remnant BH in an HMXB, probably fed by Roche lobe overflow, residing in a super-Eddington ultraluminous state. The 1.6 GHz VLBI source is consistent with radio emission from possible ballistic jet ejections in this state.

A CHANGE IN THE QUIESCENT X-RAY SPECTRUM OF THE NEUTRON STAR LOW-MASS X-RAY BINARY MXB 1659-29

Energy Technology Data Exchange (ETDEWEB)

Cackett, E. M. [Department of Physics and Astronomy, Wayne State University, 666 W. Hancock Street, Detroit, MI 48201 (United States); Brown, E. F. [Department of Physics and Astronomy, National Superconducting Cyclotron Laboratory, and the Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States); Cumming, A. [Department of Physics, McGill University, 3600 rue University, Montreal, QC H3A 2T8 (Canada); Degenaar, N.; Miller, J. M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Fridriksson, J. K.; Wijnands, R. [Astronomical Institute ' ' Anton Pannekoek' ' , University of Amsterdam, Science Park 904, 1098-XH Amsterdam (Netherlands); Homan, J., E-mail: ecackett@wayne.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States)

2013-09-10

The quasi-persistent neutron star low-mass X-ray binary MXB 1659-29 went into quiescence in 2001, and we have followed its quiescent X-ray evolution since. Observations over the first 4 yr showed a rapid drop in flux and temperature of the neutron star atmosphere, interpreted as cooling of the neutron star crust which had been heated during the 2.5 yr outburst. However, observations taken approximately 1400 and 2400 days into quiescence were consistent with each other, suggesting the crust had reached thermal equilibrium with the core. Here we present a new Chandra observation of MXB 1659-29 taken 11 yr into quiescence and 4 yr since the last Chandra observation. This new observation shows an unexpected factor of {approx}3 drop in count rate and change in spectral shape since the last observation, which cannot be explained simply by continued cooling. Two possible scenarios are that either the neutron star temperature has remained unchanged and there has been an increase in the column density, or, alternatively the neutron star temperature has dropped precipitously and the spectrum is now dominated by a power-law component. The first scenario may be possible given that MXB 1659-29 is a near edge-on system, and an increase in column density could be due to build-up of material in, and a thickening of, a truncated accretion disk during quiescence. But, a large change in disk height may not be plausible if standard accretion disk theory holds during quiescence. Alternatively, the disk may be precessing, leading to a higher column density during this latest observation.

A CENSUS OF THE SUPERSOFT X-RAY SOURCES IN M31

International Nuclear Information System (INIS)

Orio, Marina; Nelson, Thomas; Bianchini, Antonio; Di Mille, Francesco; Harbeck, Daniel

2010-01-01

We examined X-ray, ultraviolet, and optical archival data of 89 supersoft X-ray sources (SSS) in M31. We studied the timescales of X-ray variability and searched UV and optical counterparts. Almost a third of the SSS are known classical or recurrent novae, and at least half of the others exhibit the same temporal behavior as post-outburst novae. Non-stellar objects among SSS seem to be rare: less than 10% of the classified SSS turned out to be supernova remnants, and only one source has been identified with an active galactic nucleus in the background. Not more than 20% of the SSS that are not coincident with observed novae are persistent or recurrent X-ray sources. A few of these long-lasting sources show characteristics in common with other SSS identified as white dwarf (WD) close binaries in the Magellanic Clouds and in the Galaxy, including variability on timescales of minutes, possibly indicating the spin period of a WD. Such objects are likely to be low-mass X-ray binaries with a massive WD. A third of the non-nova SSS are in regions of recent star formation, often at the position of an O or B star, and we suggest that they may be high-mass X-ray binaries. If these sources host a massive hydrogen-burning WD, as it seems likely, they may become Type Ia supernovae (SNe Ia), constituting the star formation dependent component of the SNe Ia rate.

Discrimination and quantification of contamination and implanted solar wind in Genesis collector shards using grazing incidence synchrotron x-ray techniques: Initial results

International Nuclear Information System (INIS)

Kitts, K.; Sutton, S.; Eng, P.; Ghose, S.; Burnett, D.

2006-01-01

Grazing incidence X-ray fluorescence is a non-destructive technique that can differentiate the embedded solar wind component from surface contamination and collector background in the Genesis shards. Initial solar Fe abundance in D30554 is 8 x 10 12 /cm 2 . Accurate knowledge of the composition of the Sun provides a baseline, which allows an understanding of how the solar system has evolved over time and how solar processes and solar wind mechanics behave. Unfortunately, the errors in photospheric abundances are too large for many planetary science problems and this hampers our understanding of these different processes. Analyses of solar wind implanted in meteorites or lunar soils have provided more precise data but alteration processes on these bodies may complicate such information. In response to this need for pristine solar wind samples, NASA developed and launched the Genesis Probe. Unfortunately, the probe smashed into the Utah desert shattering the 300 collector plates into 15,000+ pieces all of which are now coated in a both a fine terrestrial dust and Si and Ge powder from the disrupted collectors themselves. The solar wind penetration depth is 100-200 nm and the superposed contamination layers are typically 40-50 nm. Stringent cleaning regimes have the potential of removing the solar wind itself. The best solution is to have sufficient spatial resolution to separately analyze the surface contamination and penetrated solar wind. To that end, three Genesis collector array shards and their appropriate flight spares were characterized via grazing incidence x-ray fluorescence and x-ray reflectivity. The goals were (1) to evaluate the various cleaning methods used to eliminate contamination, (2) to identify the collector substrates most suited for this technique, (3) to determine whether the solar wind signature could be deconvolved from the collector background signature, and (4) to measure the relative abundances of Ca to Ge in the embedded solar wind.

Application of a radioactive sourced semi portable X-ray spectrometer to the solution of binary mix compositions

International Nuclear Information System (INIS)

Butcher, B.M.

1988-01-01

In many cases it is far more economically viable to transport individual constituents to a blending plant and produce a series of custom made products than to manufacture at site. This situation exists in many heavy chemical industries or on large building sites. In the cement industry inter-mixed or interground blends containing slag, fly ash, or limestone are produced. These mixes are designed to enhance certain physical properties and to reduce costs. This paper summarises experience of the application of portable isotope source X-ray analysers in achieving quality control of binary mixes

The TeV γ-ray binary PSR B1259-63. Observations with the high energy stereoscopic system in the years 2005-2007

International Nuclear Information System (INIS)

Kerschhaggl, Matthias

2010-01-01

PSR B1259-63/SS2883 is a binary system where a 48 ms pulsar orbits a massive Be star with a period of 3.4 years. The system exhibits variable, non-thermal radiation around periastron on the highly eccentric orbit (e=0.87) visible from radio to very high energies (VHE; E>100 GeV). When being detected in TeV γ-rays with the High Energy Stereoscopic System (H.E.S.S.) in 2004 it became known as the first variable galactic VHE source. This thesis presents VHE data from PSR B1259-63 as taken during the years 2005, 2006 and before as well as shortly after the 2007 periastron passage. These data extend the knowledge of the lightcurve of this object to all phases of the binary orbit. The lightcurve constrains physical mechanisms present in this TeV source. Observations of VHE γ-rays with the H.E.S.S. telescope array using the Imaging Atmospheric Cherenkov Technique were performed. The H.E.S.S. instrument features an angular resolution of stat ±0.2 sys and flux normalisation Φ 0 =(1.1±0.1 stat ±0.2 sys ) x 10 -12 TeV -1 cm -2 s -1 . PSR B1259-63 was also monitored in 2005 and 2006, far from periastron passage, comprising 8.9 h and 7.5 h of exposure, respectively. No significant excess of γ-rays is seen in those observations. PSR B1259-63 has been re-confirmed as a variable TeV γ-ray emitter. The firm detection of VHE photons emitted at a true anomaly θ∼0.35 of the pulsar orbit, i.e. already ∝50 days prior to the periastron passage, disfavors the stellar disc target scenario as a primary emission mechanism, based on current knowledge about the companion star's disc inclination, extension, and density profile. In a phenomenological study indirect evidence that PSR B1259-63 could in fact be a periodical VHE emitter is presented using the TeV data discussed in this work. While the TeV energy flux level seems to be only dependent on the binary separation this behavior is not seen in X-rays. Moreover, model calculations based on inverse compton (IC) scattering of

The complete Einstein Observatory X-ray survey of the Orion Nebula region.

Science.gov (United States)

Gagne, Marc; Caillault, Jean-Pierre

1994-01-01

We have analyzed archival Einstein Observatory images of a roughly 4.5 square degree region centered on the Orion Nebula. In all, 245 distinct X-ray sources have been detected in six High Resolution Imager (HRI) and 17 Imaging Proportional Counter (IPC) observations. An optical database of over 2700 stars has been assembled to search for candidate counterparts to the X-ray sources. Roughly half the X-ray sources are identified with a single Orion Nebula cluster member. The 10 main-sequence O6-B5 cluster stars detected in Orion have X-ray activity levels comparable to field O and B stars. X-ray emission has also been detected in the direction of four main-sequence late-B and early-A type stars. Since the mechanisms producing X-rays in late-type coronae and early-type winds cannot operate in the late-B and early-A type atmospheres, we argue that the observed X-rays, with L(sub X) approximately = 3 x 10(exp 30) ergs/s, are probably produced in the coronae of unseen late-type binary companions. Over 100 X-ray sources have been associated with late-type pre-main sequence stars. The upper envelope of X-ray activity rises sharply from mid-F to late-G, with L(sub x)/L(sub bol) in the range 10(exp -4) to 2 x 10(exp -3) for stars later than approximately G7. We have looked for variability of the late-type cluster members on timescales of a day to a year and find that 1/4 of the stars show significantly variable X-ray emission. A handful of the late-type stars have published rotational periods and spectroscopic rotational velocities; however, we see no correlation between X-ray activity and rotation. Thus, for this sample of pre-main-sequence stars, the large dispersion in X-ray activity does not appear to be caused by the dispersion in rotation, in contrast with results obtained for low-mass main-sequence stars in the Pleiades and pre-main-sequence stars in Taurus-Auriga.

The missing GeV γ-ray binary: searching for HESS J0632+057 with Fermi-LAT

NARCIS (Netherlands)

Caliandro, G.A.; Hill, A.B.; Torres, D.F.; Hadasch, D.; Ray, P.; Abdo, A.; Hessels, J.W.T.; Ridolfi, A.; Possenti, A.; Burgay, M.; Rea, N.; Tam, P.H.T.; Dubois, R.; Dubus, G.; Glanzman, T.; Jogler, T.

2013-01-01

The very high energy (VHE; >100 GeV) source HESS J0632+057 has been recently confirmed as a γ-ray binary, a subclass of the high-mass X-ray binary population, through the detection of an orbital period of 321 d. We performed a deep search for the emission of HESS J0632+057 in the GeV energy range

The Correlation between Hard X-Ray Peak Flux and Soft X-Ray Peak Flux in the Outburst Rise of Low-Mass X-Ray Binaries

NARCIS (Netherlands)

Yu, W.; van der Klis, M.; Fender, R.P.

2004-01-01

We have analyzed Rossi X-Ray Timing Explorer pointed observations of the outbursts of black hole and neutron star soft X-ray transients in which an initial low/hard state, or ``island'' state, followed by a transition to a softer state was observed. In three sources-the black hole transient XTE

Introductory Overview of Intermediate-luminosity X-ray Objects

Science.gov (United States)

Colbert, E. J. M.

2001-05-01

Intermediate-luminosity X-ray Objects (IXOs) are defined as compact objects having X-ray luminosities between those of X-ray binaries and low-luminosity AGNs (i.e., 1039.0 erg s-1 < ~ LX [IXOs] < ~ 1041.0 erg s-1). It is not currently known if these objects are intermediate-mass (M ~ 102-104 Msun) black holes accreting near the Eddington limit, near-solar-mass black holes in a super-Eddington state, or are, in some cases, just supermassive black holes accreting at very low rates. However, the first idea has been popularized by recent press coverage. IXOs are quite common (present in about half of spiral galaxies) and are typically found displaced from the optical nucleus, reducing the likelihood that they are low-luminosity AGN. Nearly all of our knowledge of these objects comes from X-ray observations, as observations of optical, NIR and radio counterparts are not widely known. In this session, we will address (1) the phenomenology of the objects, (2) possible geometry and accretion mechanisms for these objects (i.e., are they more similar to black hole X-ray binaries or AGNs), (3) the central black hole masses, and (4) the formation mechanism for these black holes, if they are of intermediate mass. In this talk, I will focus primarily on giving background information of these fascinating objects.

A NuSTAR Observation of the Reflection Spectrum of the Low-Mass X-Ray Binary 4U 1728-34

Science.gov (United States)

Sleator, Clio C.; Tomsick, John A.; King, Ashley L.; Miller, Jon M.; Boggs, Steven E.; Bachetti, Matteo; Barret, Didier; Chenevez, Jerome; Christensen, Finn E.; Craig, William W.;