A5040293065- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- High-pressure geophysics and materials
- Astronomical Observations and Instrumentation
- Mechanics and Biomechanics Studies
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Particle Detector Development and Performance
- Astrophysics and Cosmic Phenomena
- CCD and CMOS Imaging Sensors
- Nuclear Physics and Applications
- SAS software applications and methods
- Adaptive optics and wavefront sensing
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
- Scientific Measurement and Uncertainty Evaluation
- Galaxies: Formation, Evolution, Phenomena
- Advanced X-ray Imaging Techniques
- Statistical and numerical algorithms
- Astrophysics and Star Formation Studies
- Ionosphere and magnetosphere dynamics
- Infrared Target Detection Methodologies
- Geophysics and Sensor Technology
SRON Netherlands Institute for Space Research
2013-2024
Massachusetts Institute of Technology
2017
University of Amsterdam
2017
Monash University
2017
Leiden University
2017
Utrecht University
2001-2008
National Institute for Space Research
2005
Roma Tre University
2003
Goddard Space Flight Center
1996-1997
National Academies of Sciences, Engineering, and Medicine
1997
We examined the maximum bolometric peak luminosities during type I X-ray bursts from persistent or transient luminous sources in globular clusters. show that for about two thirds of photospheric radius expansion extend to a critical value erg s-1, assuming total burst emission is entirely due black-body radiation and recorded luminosity actual luminosity. This empirical consistent with Eddington limit hydrogen poor material. Since more less always reached (except one source), such may be...
Ultracompact X-ray binaries (UCXBs) appear able to sustain accretion onto the compact accretor at rates lower than in wider binaries. This may be understood by smaller disks UCXBs: a luminosity suffices keep disk completely ionized through irradiation and, thus, viscosity sufficiently high level allow effective transport of matter object. We employ this distinguishing factor on data from RXTE and BeppoSAX identify six new candidate UCXBs, thus increasing population one quarter. The...
IGR J17544-2619 belongs to a distinct group of at least seven fast X-ray transients that cannot readily be associated with nearby flare stars or pre-main sequence and most probably are binaries wind accretion. Sofar, the nature accretor has been determined in only one case (SAX J1819.3-2525/V4641 Sgr). We carried out 20 ks Chandra ACIS-S observation which shows source quiescence going into outburst. The position confirms previous tentative identification optical counterpart, blue O9Ib...
We report the discovery by Rossi X-Ray Timing Explorer Proportional Counter Array of a second transient accreting millisecond pulsar, XTE J1751-305, during regular monitoring observations Galactic bulge region. The pulsar has spin frequency 435 Hz, making it one fastest pulsars. pulsations contain signature orbital Doppler modulation, which implies an period 42 minutes, shortest any known radio or X-ray pulsar. mass function, fX = (1.278 ± 0.003) × 10-6 M☉, yields minimum for companion...
We report the possible detection (99.3% of statistical significance) redshifted Fe iron line emission in X-ray afterglow Gamma-ray burst GRB970508 observed by BeppoSAX. Its energy is consistent with redshift putative host galaxy determined from optical spectroscopy. The disappeared about 1 day after burst. have also analyzed spectral variability during outburst event that characterizes this GRB. spectrum gets harder flare, turning to steep when flux decreases. variability, intensity and...
We report the detection (3 sigma significance level) of a strong iron emission line in X-ray spectrum afterglow GRB 000214 (``Valentine's Day Burst'') observed by BeppoSAX. An feature was with centroid energy 4.7+/-0.2 keV which, if interpreted as K-alpha from hydrogen-like iron, corresponds to redshift z=0.47. The intensity (EW ~2 keV) and duration (tens hours) give information on distance, burst region, emitting material (R>3x10^15 cm) its mass (M>1.4 solar mass). These results are not...
Two types of long-duration type I X-ray bursts have been discovered by long-term monitoring observations accreting neutron stars: superbursts and ``intermediate duration'' bursts. We investigate the sensitivity their ignition conditions to interior thermal properties star. First, we compare observed superburst light curves cooling models. Our fits require column depths in range (0.5-3) × 1012 g cm-2 an energy release ≈2 1017 ergs g-1. The implied carbon fraction is XC > 10%, constraining...
We report on millisecond variability from the X-ray transient XTE J1739-285. detected six type I bursts and found evidence for oscillations at 1122 +/- 0.3 Hz in brightest burst. Taking into consideration power number of trials search, detection is significant 99.96% confidence level. If are confirmed, oscillation frequency would suggest that J1739-285 contains fastest rotating neutron star yet found. also quasiperiodic persistent emission with frequencies ranging 757 to 862 Hz. Using burst,...
We present BeppoSAX follow-up observations of GRB 980425 obtained with the Narrow Field Instruments (NFI) in 1998 April, May, and November. The first NFI observation has detected within 8' radius error box gamma-ray burst (GRB) an X-ray source positionally consistent supernova 1998bw, which exploded a day 980425, fainter source, not position supernova. former is following pointings exhibits decline factor 2 six months. If it associated SN this detection emission from Type I above keV. latter...
We present the first results of our X-ray monitoring campaign on a 1.7 square degree region centered Sgr A* using satellites XMM-Newton and Chandra. The purpose this is to monitor behavior (below 10 keV) sources (both persistent transient) which are too faint be detected by instruments aboard other currently in orbit (e.g., Rossi Timing Explorer; INTEGRAL). Our observations (using HRC-I Chandra) were obtained June 5, 2005. Most could identified with foreground sources, such as active stars....
We present an overview of BeppoSAX Wide Field Cameras observations the nine most frequent type I X-ray bursters in Galactic center region. Six years (from 1996 to 2002) have amounted 7 Ms and detection 1823 bursts. The 3 are GX 354-0 (423 bursts), KS 1731-260 (339) GS 1826-24 (260). These numbers reflect unique dataset. show that all sources same global burst behavior as a function luminosity. At lowest luminosities () bursts occur quasi-periodically rate increases linearly with accretion...
2S 0918-549 is a low-mass X-ray binary (LMXB) with low optical to flux ratio. Probably it an ultracompact orbital period shorter than 60 min. Such binaries cannot harbor hydrogen rich donor stars. As other (sometimes confirmed) LMXBs, observed have high neon-to-oxygen abundance ratio (Juett et al. 2001) which has been used argue that the companion star CO or ONe white dwarf. However, type-I bursts from several of these systems implying presence helium on neutron surface. In this paper, we in...
We present a detailed spectral analysis of the prompt and afterglow emission four nearby long-soft gamma-ray bursts (GRBs 980425, 030329, 031203, 060218) that were spectroscopically found to be associated with type Ic supernovae, compare them general GRB population. For each event, we investigate luminosity evolution, estimate total energy budget based upon broadband observations. The observational inventory for these events has become rich enough allow estimates their content in...
[abridged] The LMXB 4U 0614+091 is a source of sporadic thermonuclear (type I) X-ray bursts. We find bursts with wide variety characteristics in serendipitous wide-field observations by EURECA/WATCH, RXTE/ASM, BeppoSAX/WFC, HETE-2/FREGATE, INTEGRAL/IBIS/ISGRI, and Swift/BAT, as well pointed RXTE/PCA HEXTE. Most them reach peak flux ~15 Crab, but few only below Crab. One the shows very strong photospheric radius-expansion phase. This allows us to evaluate distance source: 3.2 kpc. burst...
The prototypical accretion-powered millisecond pulsar SAX J1808.4-3658 was observed simultaneously with Chandra-LETGS and RXTE-PCA near the peak of a transient outburst in November 2011. A single thermonuclear (type-I) burst detected, brightest yet by Chandra from any source, second-brightest RXTE. We found no evidence for discrete spectral features during burst; absorption edges have been predicted to be present such bursts, but may require greater degree photospheric expansion than rather...
Since the discovery of accreting millisecond pulsar XTE J1814-338, a total 27 thermonuclear bursts have been observed from source with Proportional Counter Array on board Rossi X-Ray Timing Explorer. Spectroscopy bursts, as well presence continuous burst oscillations, suggests that all but one are sub-Eddington. The remaining has largest peak bolometric flux 2.64 × 10-8 ergs s-1 cm-2, gap in similar to seen Eddington-limited other sources. Assuming this was Eddington limited, we obtain...
We report on the results of a deep 1.6 Ms INTEGRAL observation Cassiopeia region performed from December 2003 to February 2004. Eleven sources were detected with imager IBIS-ISGRI at energies above 20 keV, including three new hard X-ray sources. Most remarkable is discovery emission anomalous pulsar 4U 0142+61, which shows up ~150 keV very power-law spectrum photon index ± 0.17. derived flux upper limits for between 0.75 MeV and 30 using archival data Compton telescope COMPTEL. In order...
We have discovered three certain (SAX J1324.5-6313, 2S 1711-339 and SAX J1828.5-1037) two likely J1818.7+1424 J2224.9+5421) new thermonuclear X-ray burst sources with the BeppoSAX Wide Field Cameras, observed a second ever from sixth one (2S 0918-549). Four of them (excluding 0918-549) are newly detected which we single bursts, but no persistent emission. observe first 11 bursts 1711-339; flux was during ten not around last burst. A recently 0918-549 by Jonker et al. (2001); showing radius...
Type I X-ray bursts from low-mass binaries result a thermonuclear runaway in the material accreted onto neutron star. Although typical recurrence times are few hours, consistent with theoretical ignition model predictions, there also observations of occurring as promptly ten minutes or less after previous event. We present comprehensive assessment this phenomenon using catalog 3387 observed BeppoSAX/WFCs and RXTE/PCA instruments. This contains 136 than one hour, that come multiples up to...
A small subset of thermonuclear X-ray bursts on neutron stars exhibit such a strong photospheric expansion that for few seconds the photosphere is located at radius <i>r<i/><sub>ph<sub/> 10<sup>3<sup/> km. Such “superexpansions” imply large and rapid energy release, feature characteristic pure He burst models. Previous calculations have shown during burst, freshly synthesized heavy-element ashes burning can be ejected in radiative wind produce significant spectral absorption features. We...
We introduce the Galactic Bulge Survey (GBS) and we provide Chandra source list for region that has been observed to date. Among goals of GBS are constraining neutron star (NS) equation state black hole (BH) mass distribution via identification eclipsing NS BH low-mass X-ray binaries (LMXBs). The latter goal will, in addition, be obtained by significantly enlarging number systems which a can derived. Further include binary formation scenarios, particular common envelope phase occurrence...