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M. H. M. Heemskerk

Bio: M. H. M. Heemskerk is an academic researcher from University of Amsterdam. The author has contributed to research in topics: Gamma-ray burst & Afterglow. The author has an hindex of 7, co-authored 12 publications receiving 369 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a spectroscopic monitoring campaign of the OB-star companions to the eclipsing X-ray pulsars SMC X−1, LMC X−4 and Cen X−3 is presented.
Abstract: We present the results of a spectroscopic monitoring campaign of the OB-star companions to the eclipsing X-ray pulsars SMC X−1, LMC X−4 and Cen X−3. High-resolution optical spectra obtained with UVES on the ESO Very Large Telescopeare used to determine the radial-velocity orbit of the OB (super)giants with high precision. The excellent quality of the spectra provides th e opportunity to measure the radial-velocity curve based on individual lines, and to study the effect of possible distortions of the line profiles due to e.g. X-ray heating on the derived radial-velocity amplitude. Several spectral lines show intrinsic variations with or bital phase. The magnitude of these variations depends on line strength, and thus provides a criterion to select lines that do not suffer from distortions. The undistorted lines show a larger radial-velocity amplit ude than the distorted lines, consistent with model predict ions. Application of our line-selection criteria results in a mean radial-vel ocity amplitude Kopt of 20.2±1.1, 35.1±1.5, and 27.5±2.3 km s −1 (1σ errors), for the OB companion to SMC X−1, LMC X−4 and Cen X−3, respectively. Adding information on the projected rotational velocity of the OB companion (derived from our spectra), the duration of X-ray eclipse and orbital parameters of the X-ray pulsar (obtained from literature), we arrive at a neutron star mass of 1.06 +0.11 −0.10 , 1.25 +0.11 −0.10 and 1.34 +0.16 −0.14 M⊙ for SMC X−1, LMC X−4 and Cen X−3, respectively. The mass of SMC X−1 is near the minimum mass (∼1 M⊙) expected for a neutron star produced in a supernova. We discuss the implications of the measured mass distribution on the neutron-star formation mechanism, in relation to the evolutionary history of the massive binaries.

99 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used a new approach to obtain limits on the absorbing columns toward an initial sample of 10 long gamma-ray bursts observed with BeppoSAX and selected on the basis of their good optical and near-infrared (NIR) coverage, from simultaneous fits to NIR, optical, and X-ray afterglow data, in count space and including the effects of metallicity.
Abstract: We use a new approach to obtain limits on the absorbing columns toward an initial sample of 10 long gamma-ray bursts observed with BeppoSAX and selected on the basis of their good optical and near-infrared (NIR) coverage, from simultaneous fits to NIR, optical, and X-ray afterglow data, in count space and including the effects of metallicity. In no cases is a Milky Way-like (MW) extinction preferred when testing MW, LMC, and SMC extinction laws. The 2175 A bump would in principle be detectable in all these afterglows, but is not present in the data. An SMC-like gas-to-dust ratio or lower value can be ruled out for four of the hosts analyzed here (assuming SMC metallicity and extinction law), while the remainder of the sample have too large an error to discriminate. We provide a more accurate estimate of the line-of-sight extinction and improve on the uncertainties for the majority of the extinction measurements made in previous studies of this sample. We discuss this method for determining extinction values in comparison with the most commonly employed existing methods.

88 citations

Journal ArticleDOI
TL;DR: In this article, the authors used a new approach to obtain limits on the absorbing columns towards an initial sample of 10 long Gamma-Ray Bursts observed with BeppoSAX and selected on the basis of their good optical and nIR coverage, from simultaneous fits to nIR, optical and X-ray afterglow data, in count space and including the effects of metallicity.
Abstract: We use a new approach to obtain limits on the absorbing columns towards an initial sample of 10 long Gamma-Ray Bursts observed with BeppoSAX and selected on the basis of their good optical and nIR coverage, from simultaneous fits to nIR, optical and X-ray afterglow data, in count space and including the effects of metallicity. In no cases is a MW-like extinction preferred, when testing MW, LMC and SMC extinction laws. The 2175A bump would in principle be detectable in all these afterglows, but is not present in the data. An SMC-like gas-to-dust ratio or lower value can be ruled out for 4 of the hosts analysed here (assuming SMC metallicity and extinction law) whilst the remainder of the sample have too large an error to discriminate. We provide a more accurate estimate of the line-of-sight extinction and improve upon the uncertainties for the majority of the extinction measurements made in previous studies of this sample. We discuss this method to determine extinction values in comparison with the most commonly employed existing methods.

78 citations

Journal ArticleDOI
TL;DR: In this article, a spectroscopic monitoring campaign of the OB-star companions to the eclipsing X-ray pulsars SMC X-1, LMC X-4 and Cen X-3 is presented.
Abstract: We present the results of a spectroscopic monitoring campaign of the OB-star companions to the eclipsing X-ray pulsars SMC X-1, LMC X-4 and Cen X-3. High-resolution optical spectra obtained with UVES on the ESO Very Large Telescope are used to determine the radial-velocity orbit of the OB (super)giants with high precision. The excellent quality of the spectra provides the opportunity to measure the radial-velocity curve based on individual lines, and to study the effect of possible distortions of the line profiles due to e.g. X-ray heating on the derived radial-velocity amplitude. Several spectral lines show intrinsic variations with orbital phase. The magnitude of these variations depends on line strength, and thus provides a criterion to select lines that do not suffer from distortions. The undistorted lines show a larger radial-velocity amplitude than the distorted lines, consistent with model predictions. Application of our line-selection criteria results in a mean radial-velocity amplitude K(Opt) of 20.2 +/- 1.1, 35.1 +/- 1.5, and 27.5 +/- 2.3 km/s (1 sigma errors), for the OB companion to SMC X-1, LMC X-4 and Cen X-3, respectively. Adding information on the projected rotational velocity of the OB companion (derived from our spectra), the duration of X-ray eclipse and orbital parameters of the X-ray pulsar (obtained from literature), we arrive at a neutron star mass of 1.06^{+0.11}_{-0.10}, 1.25^{+0.11}_{-0.10} and 1.34^{+0.16}_{-0.14} M{sun} for SMC X-1, LMC X-4 and Cen X-3, respectively. The mass of SMC X-1 is near the minimum mass (~1 M{sun}) expected for a neutron star produced in a supernova. We discuss the implications of the measured mass distribution on the neutron-star formation mechanism, in relation to the evolutionary history of the massive binaries.

66 citations

Journal ArticleDOI
TL;DR: In this article, a method of simultaneous multi-parameter fitting of GRB afterglow optical and near infrared, spectral energy distributions is proposed to estimate the photometric redshift, spectral index and host extinction.
Abstract: Theory suggests that about 10% of Swift-detected gamma-ray bursts (GRBs) will originate at redshifts greater than 5 yet a number of high redshift candidates may be left unconfirmed due to the lack of measured redshifts. Here we introduce our code, GRBz, a method of simultaneous multi-parameter fitting of GRB afterglow optical and near infrared, spectral energy distributions. It allows for early determinations of the photometric redshift, spectral index and host extinction to be made. We assume that GRB afterglow spectra are well represented by a power-law decay and model the effects of absorption due to the Lyman forest and host extinction. We use a genetic algorithm-based routine to simultaneously fit the parameters of interest, and a Monte Carlo error analysis. We use GRBs of previously determined spectroscopic redshifts to prove our method, while also introducing new near infrared data of GRB 990510 which further constrains the value of the host extinction. Our method is effective in estimating the photometric redshift of GRBs, relatively unbiased by assumptions of the afterglow spectral index or the host galaxy extinction. Monte Carlo error analysis is required as the method of error estimate based on the optimum population of the genetic algorithm underestimates errors significantly.

18 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, it was shown that most long-duration soft-spectrum gamma-ray bursts are accompanied by massive stellar explosions (GRB-SNe) and that most of the energy in the explosion is contained in nonrelativistic ejecta (producing the supernova) rather than in the relativistic jets responsible for making the burst and its afterglow.
Abstract: Observations show that at least some gamma-ray bursts (GRBs) happen simultaneously with core-collapse supernovae (SNe), thus linking by a common thread nature's two grandest explosions. We review here the growing evidence for and theoretical implications of this association, and conclude that most long-duration soft-spectrum GRBs are accompanied by massive stellar explosions (GRB-SNe). The kinetic energy and luminosity of well-studied GRB-SNe appear to be greater than those of ordinary SNe, but evidence exists, even in a limited sample, for considerable diversity. The existing sample also suggests that most of the energy in the explosion is contained in nonrelativistic ejecta (producing the supernova) rather than in the relativistic jets responsible for making the burst and its afterglow. Neither all SNe, nor even all SNe of Type Ibc produce GRBs. The degree of differential rotation in the collapsing iron core of massive stars when they die may be what makes the difference.

1,389 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive sample of all gamma-ray burst (GRB) afterglows with known distances is presented, and their conical opening angles are derived based on observed broadband breaks in their light curves.
Abstract: We present a comprehensive sample of all gamma-ray burst (GRB) afterglows with known distances, and we derive their conical opening angles based on observed broadband breaks in their light curves. Within the framework of this conical jet model, we correct for the geometry and we find that the gamma-ray energy release is narrowly clustered around 5 × 10^(50) ergs. We draw three conclusions. First, the central engines of GRBs release energies that are comparable to ordinary supernovae. Second, the broad distribution in fluence and luminosity for GRBs is largely the result of a wide variation of opening angles. Third, only a small fraction of GRBs are visible to a given observer, and the true GRB rate is several hundred times larger than the observed rate.

1,225 citations

Journal ArticleDOI
TL;DR: In this paper, the authors derived the mass distributions of stellar compact remnants and provided analytic prescriptions for both single-star models (as a function of initial star mass) and binary-star model-prescriptions for compact object masses for major population synthesis codes.
Abstract: The mass distribution of neutron stars and stellar-mass black holes provides vital clues into the nature of stellar core collapse and the physical engine responsible for supernova explosions. A number of supernova engines have been proposed: neutrino- or oscillation-driven explosions enhanced by early (developing in 10-50 ms) and late-time (developing in 200 ms) convection as well as magnetic field engines (in black hole accretion disks or neutron stars). Using our current understanding of supernova engines, we derive mass distributions of stellar compact remnants. We provide analytic prescriptions for both single-star models (as a function of initial star mass) and for binary-star models-prescriptions for compact object masses for major population synthesis codes. These prescriptions have implications for a range of observations: X-ray binary populations, supernova explosion energies, and gravitational wave sources. We show that advanced gravitational radiation detectors (like LIGO/VIRGO or the Einstein Telescope) will be able to further test the supernova explosion engine models once double black hole inspirals are detected.

646 citations

Journal ArticleDOI
TL;DR: In this article, the authors derived mass distributions of stellar compact remnants and provided analytical prescriptions for compact object masses for major population synthesis codes, and demonstrated that these qualitatively new results for compact objects can explain the observed gap in the remnant mass distribution between ~2-5 solar masses and place strong constraints on the nature of the supernova engine.
Abstract: The mass distribution of neutron stars and stellar-mass black holes provides vital clues into the nature of stellar core collapse and the physical engine responsible for supernova explosions. Using recent advances in our understanding of supernova engines, we derive mass distributions of stellar compact remnants. We provide analytical prescriptions for compact object masses for major population synthesis codes. In an accompanying paper, Belczynski et al., we demonstrate that these qualitatively new results for compact objects can explain the observed gap in the remnant mass distribution between ~2-5 solar masses and that they place strong constraints on the nature of the supernova engine. Here, we show that advanced gravitational radiation detectors (like LIGO/VIRGO or the Einstein Telescope) will be able to further test the supernova explosion engine models once double black hole inspirals are detected.

499 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigate the distribution of neutron star masses in different populations of binaries, employing Bayesian statistical techniques, and explore the differences in neutron star mass between sources that have experienced distinct evolutionary paths and accretion episodes.
Abstract: We investigate the distribution of neutron star masses in different populations of binaries, employing Bayesian statistical techniques. In particular, we explore the differences in neutron star masses between sources that have experienced distinct evolutionary paths and accretion episodes. We find that the distribution of neutron star masses in non-recycled eclipsing high-mass binaries as well as of slow pulsars, which are all believed to be near their birth masses, has a mean of 1.28 M ☉ and a dispersion of 0.24 M ☉. These values are consistent with expectations for neutron star formation in core-collapse supernovae. On the other hand, double neutron stars, which are also believed to be near their birth masses, have a much narrower mass distribution, peaking at 1.33 M ☉, but with a dispersion of only 0.05 M ☉. Such a small dispersion cannot easily be understood and perhaps points to a particular and rare formation channel. The mass distribution of neutron stars that have been recycled has a mean of 1.48 M ☉ and a dispersion of 0.2 M ☉, consistent with the expectation that they have experienced extended mass accretion episodes. The fact that only a very small fraction of recycled neutron stars in the inferred distribution have masses that exceed ~2 M ☉ suggests that only a few of these neutron stars cross the mass threshold to form low-mass black holes.

336 citations