Bruce Gendre | University of the Virgin Islands (original) (raw)

Papers by Bruce Gendre

GRB Coordinates Network, 2016

GRB Coordinates Network, May 1, 2017

GRB Coordinates Network, 2013

GRB Coordinates Network, 2016

GRB Coordinates Network, 2016

Presently only 30 and this sample is highly biased by the limited sensitivity of Swift to detect ... more Presently only 30 and this sample is highly biased by the limited sensitivity of Swift to detect SGRBs. We account for the dominant biases to calculate a realistic SGRB rate density out to z = 0.5 using the Swift sample of peak fluxes, redshifts, and those SGRBs with a beaming angle constraint from X-ray/optical observations. Assuming a significant fraction of binary neutron star mergers produce SGRBs, we calculate lower and upper detection rate limits of (1-180) per Yr by an advanced LIGO and Virgo coincidence search. Our detection rate is compatible with extrapolations using Galactic pulsar observations and population synthesis.

Experimental Astronomy, 2021

Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with the potenti... more Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with the potential to span a vast range of redshifts. The growing synergies between different probes is opening new frontiers, which promise profound insights into several aspects of fundamental physics and cosmology. In this context, THESEUS will play a central role during the 2030s in detecting and localizing the electromagnetic counterparts of gravitational wave and neutrino sources that the unprecedented sensitivity of next generation detectors will discover at much higher rates than the present. Here, we review the most important target signals from multi-messenger sources that THESEUS will be able to detect and characterize, discussing detection rate expectations and scientific impact.

Discourse, 2017

The data required for formation of an integrated indicator of effective management of IT services... more The data required for formation of an integrated indicator of effective management of IT services of a digital enterprise in the conditions of introduction of technological innovations as sets of key indicators of effective management of IT infrastructure of the digital enterprise and key indicators of effective management of life cycle of technological innovations are presented. Descriptions of key performance indicators of IT services management, IT infrastructure of the digital enterprise are provided in article. Approaches to formation of key performance indicators of data management of multilevel storage by the example of data storage technologies of the information system SAP NW BW/4HANA are given.

GRB 130925A is a peculiar event characterized by an extremely long gamma-ray duration (≈7 ks), as... more GRB 130925A is a peculiar event characterized by an extremely long gamma-ray duration (≈7 ks), as well as dramatic flaring in the X-rays for ≈20 ks. After this period, its X-ray afterglow shows an atypical soft spectrum with photon index Γ∼4, as observed by Swift and Chandra, until ≈ 10 7 s, when XMM-Newton observations uncover a harder spectral shape with Γ∼2.5, commonly observed in GRB afterglows. We find that two distinct emission components are needed to explain the X-ray observations: a thermal component, which dominates the X-ray emission for several weeks, and a non-thermal component, consistent with a typical afterglow. A forward shock model well describes the broadband (from radio to X-rays) afterglow spectrum at various epochs. It requires an ambient medium with a very low density wind profile, consistent with that expected from a low-metallicity blue supergiant (BSG). The thermal component has a remarkably constant size and a total energy consistent with those expected by a hot cocoon surrounding the relativistic jet. We argue that the features observed in this GRB (its ultralong duration, the thermal cocoon, and the low density wind environment) are associated with a low metallicity BSG progenitor and, thus, should characterize the class of ultralong GRBs.

We present a set of seventeen Gamma-Ray Bursts (GRBs) with known redshifts and X-ray afterglow em... more We present a set of seventeen Gamma-Ray Bursts (GRBs) with known redshifts and X-ray afterglow emission. We apply cosmological corrections in order to compare their fluxes normalized at a redshift of 1. Two classes of GRB can be defined using their X-ray afterglow light curves. We show that the brightest afterglows seem to decay faster than the dimer ones. We also point out evidences for a possible flux limit of the X-ray afterglow depending on the time elapsed since the burst. We try to interpret these observations in the framework of the canonical fireball model of GRB afterglow emission.

Abstract. We have examined preliminary data of the globular cluster, M22, from the EPIC MOS detec... more Abstract. We have examined preliminary data of the globular cluster, M22, from the EPIC MOS detectors on board XMM-Newton. We have detected 27 X-ray sources within the centre of the field of view, 24 of which are new detections. Three sources were found within the core of the cluster. From spectral analysis of the X-ray sources, it is possible that the object at the centre of the core is a quiescent X-ray transient and those lying further out are maybe cataclysmic variables.

Revista Mexicana de Astronomía y Astrofísica Serie de Conferencias, 2021

The 1.0 metre f/4 fast-slew Zadko Telescope was installed in June 2008 approximately seventy kilo... more The 1.0 metre f/4 fast-slew Zadko Telescope was installed in June 2008 approximately seventy kilometres north of Perth at Yeal, in the Shire of Gingin, Western Australia. Since the Zadko Telescope has been in operation it has proven its worth by detecting numerous Gamma Ray Burst afterglows, two of these being the most distant 'optical transients' imaged by an Australian telescope. Other projects include a contract with the European Space Agency (ESA) to image potentially hazardous near Earth asteroids (2019), monitoring space weather on nearby stars (2019), and photometry of a transit of Saturn's moon Titan (2018). Another active Zadko Telescope project is tracking Geostationary satellites and attempting to use photometry to classify various space debris (defunct satellites). The Zadko Telescope's importance as a potential tool for education, training, and public outreach cannot be underestimated, as the global awareness of the importance of astronomy (and space sci...

GRB Coordinates Network, 2020

arXiv: High Energy Astrophysical Phenomena, 2013

The coalescence of two compact objects is a key target for the new gravitational wave observatori... more The coalescence of two compact objects is a key target for the new gravitational wave observatories such as Advanced-Virgo (AdV), Advanced-LIGO (aLIGO) and KAGRA. This phenomenon can lead to the simultaneous detection of electromagnetic waves in the form of short GRBs (sGRBs) and gravitational wave transients. This will potentially allow for the first time access to the fireball and the central engine properties. We present an estimation of the detection rate of such events, seen both by a Swift-like satellite and AdV/ALIGO. This rate is derived only from the observations of sGRBs. We show that this rate, if not very high, predicts a few triggers during the whole life time of Advanced LIGO-Virgo. We discuss how to increase it using some dedicated observational strategies. We apply our results to other missions such as the SVOM French-Chinese satellite project or LOFT.

Mobile ad hoc networks are designed to maintain communication among the independent nodes without... more Mobile ad hoc networks are designed to maintain communication among the independent nodes without a server or base station. High efficient MAC protocol takes a major role to maintain collision free, bandwidth efficient communication among the networked nodes. Collisions among the nodes provide considerable reduction in the performance of the network. The objective of the work is to provide collision aware cooperative MAC protocol design by modifying the backoff to a specific range. It improves the throughput and reduces delay with less collision rate. It minimizes the complexity of the problem arising in memory and processing.

GRB Coordinates Network, 2016

GRB Coordinates Network, May 1, 2017

GRB Coordinates Network, 2013

GRB Coordinates Network, 2016

GRB Coordinates Network, 2016

Presently only 30 and this sample is highly biased by the limited sensitivity of Swift to detect ... more Presently only 30 and this sample is highly biased by the limited sensitivity of Swift to detect SGRBs. We account for the dominant biases to calculate a realistic SGRB rate density out to z = 0.5 using the Swift sample of peak fluxes, redshifts, and those SGRBs with a beaming angle constraint from X-ray/optical observations. Assuming a significant fraction of binary neutron star mergers produce SGRBs, we calculate lower and upper detection rate limits of (1-180) per Yr by an advanced LIGO and Virgo coincidence search. Our detection rate is compatible with extrapolations using Galactic pulsar observations and population synthesis.

Experimental Astronomy, 2021

Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with the potenti... more Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with the potential to span a vast range of redshifts. The growing synergies between different probes is opening new frontiers, which promise profound insights into several aspects of fundamental physics and cosmology. In this context, THESEUS will play a central role during the 2030s in detecting and localizing the electromagnetic counterparts of gravitational wave and neutrino sources that the unprecedented sensitivity of next generation detectors will discover at much higher rates than the present. Here, we review the most important target signals from multi-messenger sources that THESEUS will be able to detect and characterize, discussing detection rate expectations and scientific impact.

Discourse, 2017

The data required for formation of an integrated indicator of effective management of IT services... more The data required for formation of an integrated indicator of effective management of IT services of a digital enterprise in the conditions of introduction of technological innovations as sets of key indicators of effective management of IT infrastructure of the digital enterprise and key indicators of effective management of life cycle of technological innovations are presented. Descriptions of key performance indicators of IT services management, IT infrastructure of the digital enterprise are provided in article. Approaches to formation of key performance indicators of data management of multilevel storage by the example of data storage technologies of the information system SAP NW BW/4HANA are given.

GRB 130925A is a peculiar event characterized by an extremely long gamma-ray duration (≈7 ks), as... more GRB 130925A is a peculiar event characterized by an extremely long gamma-ray duration (≈7 ks), as well as dramatic flaring in the X-rays for ≈20 ks. After this period, its X-ray afterglow shows an atypical soft spectrum with photon index Γ∼4, as observed by Swift and Chandra, until ≈ 10 7 s, when XMM-Newton observations uncover a harder spectral shape with Γ∼2.5, commonly observed in GRB afterglows. We find that two distinct emission components are needed to explain the X-ray observations: a thermal component, which dominates the X-ray emission for several weeks, and a non-thermal component, consistent with a typical afterglow. A forward shock model well describes the broadband (from radio to X-rays) afterglow spectrum at various epochs. It requires an ambient medium with a very low density wind profile, consistent with that expected from a low-metallicity blue supergiant (BSG). The thermal component has a remarkably constant size and a total energy consistent with those expected by a hot cocoon surrounding the relativistic jet. We argue that the features observed in this GRB (its ultralong duration, the thermal cocoon, and the low density wind environment) are associated with a low metallicity BSG progenitor and, thus, should characterize the class of ultralong GRBs.

We present a set of seventeen Gamma-Ray Bursts (GRBs) with known redshifts and X-ray afterglow em... more We present a set of seventeen Gamma-Ray Bursts (GRBs) with known redshifts and X-ray afterglow emission. We apply cosmological corrections in order to compare their fluxes normalized at a redshift of 1. Two classes of GRB can be defined using their X-ray afterglow light curves. We show that the brightest afterglows seem to decay faster than the dimer ones. We also point out evidences for a possible flux limit of the X-ray afterglow depending on the time elapsed since the burst. We try to interpret these observations in the framework of the canonical fireball model of GRB afterglow emission.

Abstract. We have examined preliminary data of the globular cluster, M22, from the EPIC MOS detec... more Abstract. We have examined preliminary data of the globular cluster, M22, from the EPIC MOS detectors on board XMM-Newton. We have detected 27 X-ray sources within the centre of the field of view, 24 of which are new detections. Three sources were found within the core of the cluster. From spectral analysis of the X-ray sources, it is possible that the object at the centre of the core is a quiescent X-ray transient and those lying further out are maybe cataclysmic variables.

Revista Mexicana de Astronomía y Astrofísica Serie de Conferencias, 2021

The 1.0 metre f/4 fast-slew Zadko Telescope was installed in June 2008 approximately seventy kilo... more The 1.0 metre f/4 fast-slew Zadko Telescope was installed in June 2008 approximately seventy kilometres north of Perth at Yeal, in the Shire of Gingin, Western Australia. Since the Zadko Telescope has been in operation it has proven its worth by detecting numerous Gamma Ray Burst afterglows, two of these being the most distant 'optical transients' imaged by an Australian telescope. Other projects include a contract with the European Space Agency (ESA) to image potentially hazardous near Earth asteroids (2019), monitoring space weather on nearby stars (2019), and photometry of a transit of Saturn's moon Titan (2018). Another active Zadko Telescope project is tracking Geostationary satellites and attempting to use photometry to classify various space debris (defunct satellites). The Zadko Telescope's importance as a potential tool for education, training, and public outreach cannot be underestimated, as the global awareness of the importance of astronomy (and space sci...

GRB Coordinates Network, 2020

arXiv: High Energy Astrophysical Phenomena, 2013

The coalescence of two compact objects is a key target for the new gravitational wave observatori... more The coalescence of two compact objects is a key target for the new gravitational wave observatories such as Advanced-Virgo (AdV), Advanced-LIGO (aLIGO) and KAGRA. This phenomenon can lead to the simultaneous detection of electromagnetic waves in the form of short GRBs (sGRBs) and gravitational wave transients. This will potentially allow for the first time access to the fireball and the central engine properties. We present an estimation of the detection rate of such events, seen both by a Swift-like satellite and AdV/ALIGO. This rate is derived only from the observations of sGRBs. We show that this rate, if not very high, predicts a few triggers during the whole life time of Advanced LIGO-Virgo. We discuss how to increase it using some dedicated observational strategies. We apply our results to other missions such as the SVOM French-Chinese satellite project or LOFT.

Mobile ad hoc networks are designed to maintain communication among the independent nodes without... more Mobile ad hoc networks are designed to maintain communication among the independent nodes without a server or base station. High efficient MAC protocol takes a major role to maintain collision free, bandwidth efficient communication among the networked nodes. Collisions among the nodes provide considerable reduction in the performance of the network. The objective of the work is to provide collision aware cooperative MAC protocol design by modifying the backoff to a specific range. It improves the throughput and reduces delay with less collision rate. It minimizes the complexity of the problem arising in memory and processing.