A5072444894- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Mechanics and Biomechanics Studies
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Calibration and Measurement Techniques
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- Relativity and Gravitational Theory
- Astro and Planetary Science
- Radio Astronomy Observations and Technology
- Dark Matter and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Black Holes and Theoretical Physics
- Photocathodes and Microchannel Plates
- Laser-Plasma Interactions and Diagnostics
- Particle Detector Development and Performance
- Cosmology and Gravitation Theories
European Southern Observatory
2005-2023
Harvard University
2010-2019
Center for Astrophysics Harvard & Smithsonian
2011-2017
CEA Paris-Saclay
2006-2013
Université Paris Cité
2008-2013
Astrophysique, Instrumentation et Modélisation
2006-2013
Centre National de la Recherche Scientifique
2008-2013
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2006-2013
Délégation Paris 7
2008-2013
Institut Universitaire de France
2013
Context. The INTEGRAL hard X-ray observatory has revealed an emerging population of highly obscured binary systems through multi-wavelength observations. Previous studies have shown that many these sources are high-mass binaries hosting neutron stars orbiting around luminous and evolved companion stars.
Context. The INTEGRAL mission has led to the discovery of a new type supergiant X-ray binaries (SGXBs), whose physical properties differ from those previously known SGXBs. Those sources are in course being unveiled by means multi-wavelength X-rays, optical, near- and mid-infrared observations, two classes appearing. first class consists obscured persistent SGXBs second is populated so-called fast transients (SFXTs).
We present a multi-epoch hard X-ray analysis of Cygnus X-1 in its soft state based on four observations with NuSTAR. Despite the basic similarity observed spectra, there is clear spectral variability between epochs. To investigate this variability, we construct model incorporating both standard disk-corona continuum and relativistic reflection from accretion disk, prior NuSTAR work X-1, apply to each epoch independently. find excellent consistency for black hole spin, iron abundance which...
We present observations of rapid (sub-second) optical flux variability in V404 Cyg during its 2015 June outburst. Simultaneous three-band with the ULTRACAM fast imager on four nights show steep power spectra dominated by slow variations ∼100–1000 s time-scales. Near peak outburst 26, a dramatic change occurs and additional, persistent sub-second flaring appears close time to giant radio X-ray flaring. The flares reach luminosities ∼ few × 1036 erg s−1. Some are unresolved down resolution 24...
We present first results from a series of $NuSTAR$ observations the black hole X-ray binary V404 Cyg obtained during its summer 2015 outburst, primarily focusing on height this outburst activity. The data show extreme variability in both flux and spectral properties source. This is partly driven by strong variable line-of-sight absorption, similar to previous outbursts. latter stages observation are dominated flares, reaching luminosities close Eddington. During these central source appears...
Since it started observing the sky, INTEGRAL satellite has discovered new categories of high mass X-ray binaries (HMXB) in our Galaxy. These observations raise important questions on formation and evolution these rare short-lived objects. We present here infrared from which to reveal or constrain nature 15 sources, allow us update discuss Galactic HMXB population statistics. After previous photometric spectroscopic campaigns optical near-infrared, photometry spectroscopy was performed...
We report on a Spitzer/IRS (mid-infrared), RXTE/PCA+HEXTE (X-ray), and Ryle (radio) simultaneous multiwavelength study of the microquasar Cygnus X-1, which aimed at an investigation origin its mid-infrared emission. Compact jets were present in two out three observations, we show that they strongly contribute to continuum. During first observation, detect spectral break - where transition from optically thick thin regime takes place about 2.9e13 Hz. then jet's synchrotron emission accounts...
ABSTRACT During its 2005 outburst, GRO J1655–40 was observed at high spectral resolution with the Chandra High-Energy Transmission Grating Spectrometer, revealing a spectrum rich blueshifted absorption lines indicative of an accretion disk wind—apparently too hot, dense, and close to black hole be driven by radiation pressure or thermal (Miller et al.). However, this exotic wind represents just one piece puzzle in as presence coincides extremely soft curved X-ray continuum spectrum,...
Abstract We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in multi-wavelength campaign with UV data using Hubble Space Telescope Cosmic Origins Spectrograph ( HST -COS) and radio bands Jansky Very Large Array (VLA). constructed ionizing energy distribution these archival infrared to create xstar photoionization models specific flux behavior during epoch our observations. Our...
We present results from a coordinated IR-to-X-ray spectral campaign of the QSO IRAS 13349+2438. Optical spectra reveal extreme Eigenvector-1 characteristics, but H-beta line width argues against NLS1 classification; we refine z=0.10853 based on [O III]. estimate BH mass=10^9 Msun using 2 independent methods (H-beta & SED fits). Blue-shifted absorption (-950km/s -75km/s) is seen for 1st time in STIS UV Ly-alpha, NV, CIV. The higher velocity lines are coincident with lower-ionisation (xi~1.6)...
ABSTRACT We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole binary V404 Cyg in quiescence. Our coverage with NuSTAR provides very first opportunity to study spectrum at energies above 10 keV. The unabsorbed broadband (0.3–30 keV) quiescent luminosity source is 8.9 × 32 erg s −1 for a distance 2.4 kpc. shows clear variability on short timescales (an hour couple hours) radio, soft X-ray, hard bands form multiple flares. spectra obtained...
ABSTRACT Recently, unresolved hard (20–40 keV) X-ray emission has been discovered within the central 10 pc of Galaxy, possibly indicating a large population intermediate polars (IPs). Chandra and XMM-Newton measurements in surrounding ∼50 imply much lighter IPs with <?CDATA $\langle {M}_{{\rm{WD}}}\rangle \approx 0.5{M}_{\odot }$?> . Here we use broadband NuSTAR observations two IPs: TV Columbae, which fairly typical but widely varying reported mass ${M}_{{\rm{WD}}}\approx 0.5$?> –...
We present results from the spectral fitting of candidate black hole X-ray binary Swift J1753.5-0127 in an accretion state previously unseen this source. fit 0.7–78 keV spectrum with a number models, however preferred model is one multitemperature disc inner temperature kTin = 0.252 ± 0.003 scattered into steep power-law photon index |$\Gamma =6.39^{+0.08}_{-0.02}$| and additional hard tail (Γ 1.79 0.02). report on emergence strong disc-dominated component we conclude that source has entered...
The microquasar GX 339-4 experienced a new outburst in 2010: it was observed simultaneously at various wavelengths from radio up to soft gamma-rays. We focused on observations that are quasi-simultaneous with those made the INTEGRAL and RXTE satellites: these were collected 2010 March-April during our Target of Opportunity program, some other observing programs field-of-view. X-ray transients extreme systems often harbour black hole, known emit throughout whole electromagnetic spectrum when...
We present spectral analysis of Nuclear Spectroscopic Telescope Array and Swift observations Cep X-4 during its outburst in 2014. observed the source once peak decay, finding good agreement shape between observations. describe continuum using a power law with Fermi–Dirac cutoff at high energies. has very strong cyclotron resonant scattering feature (CRSF) around 30 keV. A simple absorption-like line Gaussian optical depth or pseudo-Lorentzian profile both fail to CRSF accurately, leaving...
As a complement to our optical and near-infrared study of the continuum properties GX 339-4 in two hard one soft state observations made by ESO/VLT FORS2 ISAAC early 2010, we report here on results spectral line analysis for same observations. In state, presence strong Balmer, Paschen Brackett emission lines points spectra stemming from irradiated chromosphere optically thick geometrically thin accretion disc. Most these HI features are still detected both states but veiled compact jets...
We report on quasi-simultaneous observations from radio to X-ray frequencies of the neutron star binary Aql X-1 over accretion state transitions during its 2016 outburst. All show millimetre spectra consistent with emission a jet, spectral break optically thick thin synchrotron that decreases ~100 GHz <5.5 transition hard soft state. The 5.5 flux density as source reaches state, 0.82$\pm$0.03 mJy, is highest recorded date for this source. During decay outburst, jet detected again at...
Context. IGR J18483-0311 is a high-mass X-ray binary recently discovered by INTEGRAL. Its periodic fast transient activity and its position in the Corbet diagram – although uncertain led to conclusion that source was probably Be/X-ray (BeXB), even if supergiant (SFXT) nature could not be excluded.
The Chandra High Resolution Camera observed the fields of five hard X-ray sources in order to help us obtain coordinates with sub-arcsecond precision. These observations provide most accurate positions known for IGR J16393-4643 and J17091-3624. obscured pulsar lies at R.A. (J2000) = 16:39:05.47, Dec. -46:42:13.0 (error radius 0.6" 90% confidence). This position is incompatible previously-proposed counterpart 2MASS J16390535-4642137, it points instead a new candidate that possibly blended...
We report on Chandra X-ray and Parkes radio observations of IGR J11014-6103, which is a possible pulsar wind nebula with complex morphology likely counterpart. With the superb angular resolution Chandra, we find evidence that portion extended emission may be related to bow shock due putative moving through interstellar medium. The inferred direction motion consistent J11014-6103 having been born in event produced supernova remnant (SNR) MSH 11-61A. If this association correct, then previous...
We report on Chandra observations of 18 hard X-ray (>20 keV) sources discovered with the INTEGRAL satellite near Galactic plane. For 14 sources, we have uncovered one or two potential counterparts per source. These provide soft (0.3-10 spectra and sub-arcsecond localizations, which use to identify at other wavelengths, providing information about nature each Despite fact that all are within 5 degrees plane, four IGR AGN (IGR J01545+6437, J15391-5307, J15415-5029, J21565+5948) others likely...
We report on an observation of SGR 1627-41 made with the Chandra X-ray Observatory 2011 June 16. Approximately three years after its outburst activity in 2008, source's flux has been declining, as it approaches quiescent state. For assumed power-law spectrum, we find that absorbed 2--10 keV for source is $1.0^{+0.3}_{-0.2} \times 10^{-13} erg cm^{-2} s^{-1}$ a photon index $2.9 \pm 0.8$ ($N_H=1.0\times10^{23}$ cm^{-2}). This approximately consistent measured at same time 1998. With...
AX J1745.6-2901 is a high-inclination (eclipsing) transient neutron star (NS) Low Mass X-ray Binary (LMXB) showcasing intense ionised Fe K absorption. We present here the analysis of 11 XMM-Newton and 15 NuSTAR new data-sets (obtained between 2013-2016), therefore tripling number observations in outburst. Thanks to simultaneous spectra, we greatly improve on fitting continuum. During soft state emission can be described by disk black body ($kT\sim1.1-1.2$ keV inner disc radius...
ABSTRACT The high-mass X-ray binary and accreting pulsar IGR J16393-4643 was observed by the Nuclear Spectroscope Telescope Array in 3–79 keV energy band for a net exposure time of 50 ks. We present results this observation which enabled discovery cyclotron resonant scattering feature with centroid <?CDATA ${29.3}_{-1.3}^{+1.1}$?> keV. This allowed us to measure magnetic field strength neutron star first time: B = (2.5 ± 0.1) × 10 12 G. known pulsation period is now at 904.0 0.1 s. Since...