Marc Kippen

Bio: Marc Kippen is an academic researcher from Los Alamos National Laboratory. The author has contributed to research in topics: Gamma-ray burst & Fermi Gamma-ray Space Telescope. The author has an hindex of 14, co-authored 24 publications receiving 2615 citations. Previous affiliations of Marc Kippen include Universities Space Research Association & Marshall Space Flight Center.

An Unusual Supernova in the Error Box of the Gamma-Ray Burst of 25 April 1998

Abstract: The discovery of afterglows associated with gamma-ray bursts at X-ray, optical and radio wavelengths and the measurement of the redshifts of some of these events has established that gamma-ray bursts lie at extreme distances, making them the most powerful photon-emitters known in the Universe. Here we report the discovery of transient optical emission in the error box of the gamma-ray burst GRB980425, the light curve of which was very different from that of previous optical afterglows associated with gamma-ray bursts. The optical transient is located in a spiral arm of the galaxy ESO 184-GS2, which has a redshift velocity of only 2,550 km/ s. Its optical spectrum and location indicate that it is a very luminous supernova, which has been identified as SN1998bw. If this supernova and GRB980425 are indeed associated, the energy radiated in gamma-rays is at least four orders of magnitude less than in other gamma-ray bursts, although its appearance was otherwise unremarkable: this indicates that very different mechanisms can give rise to gamma-ray bursts. But independent of this association, the supernova is itself unusual, exhibiting an unusual light curve at radio wavelengths that requires that the gas emitting the radio photons be expanding relativistically.

Detection of a Thermal Spectral Component in the Prompt Emission of GRB 100724B

Abstract: Observations of GRB 100724B with the Fermi Gamma-Ray Burst Monitor find that the spectrum is dominated by the typical Band functional form, which is usually taken to represent a non-thermal emission component, but also includes a statistically highly significant thermal spectral contribution. The simultaneous observation of the thermal and non-thermal components allows us to confidently identify the two emission components. The fact that these seem to vary independently favors the idea that the thermal component is of photospheric origin while the dominant non-thermal emission occurs at larger radii. Our results imply either a very high efficiency for the non-thermal process or a very small size of the region at the base of the flow, both quite challenging for the standard fireball model. These problems are resolved if the jet is initially highly magnetized and has a substantial Poynting flux.

Time-resolved spectroscopy of the three brightest and hardest short gamma-ray bursts observed with the Fermi gamma-ray burst monitor

Abstract: From 2008 July to 2009 October, the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope has detected 320 gamma-ray bursts (GRBs). About 20% of these events are classified as short based on their T90 duration below 2 s. We present here for the first time time-resolved spectroscopy at timescales as short as 2 ms for the three brightest short GRBs observed with GBM. The time-integrated spectra of the events deviate from the Band function, indicating the existence of an additional spectral component, which can be fit by a power law with index ∼-1.5. The time-integrated Epeak values exceed 2 MeV for two of the bursts and are well above the values observed in the brightest long GRBs. Their Epeak values and their low-energy power-law indices (a) confirm that short GRBs are harder than long ones. We find that short GRBs are very similar to long ones, but with light curves contracted in time and with harder spectra stretched toward higher energies. In our time-resolved spectroscopy analysis, we find that the Epeak values range from a few tens of keV up to more than 6MeV. In general, the hardness evolutions during the bursts follow their flux/intensity variations, similar to long bursts. However, we do not always see the Epeak leading the light-curve rises and confirm the zero/short average light-curve spectral lag below 1 MeV, already established for short GRBs. We also find that the time-resolved low-energy power-law indices of the Band function mostly violate the limits imposed by the synchrotron models for both slow and fast electron cooling and may require additional emission processes to explain the data. Finally, we interpreted these observations in the context of the current existing models and emission mechanisms for the prompt emission of GRBs.

INTEGRAL spectrometer SPI’s GRB detection capabilities : GRBs detected inside SPI’s FoV and with the anticoincidence system ACS

Abstract: The spectrometer SPI, one of the two main instruments of the INTEGRAL spacecraft, oers significant gamma- ray burst detection capabilities. In its 35 (full width) field of view SPI is able to localise gamma-ray bursts at a mean rate of0.8/month. With its large anticoincidence shield of 512 kg of BGO crystals SPI is able to detect gamma-ray bursts quasi omni-directionally with a very high sensitivity. Burst alerts of the anticoincidence shield are distributed by the INTEGRAL Burst Alert System. In the first 8 months of the mission about 0.8/day gamma-ray burst candidates and 0.3/day gamma-ray burst positions were obtained with the anticoincidence shield by interplanetary network triangulations with other spacecrafts.

Time-Resolved Spectroscopy of the 3 Brightest and Hardest Short Gamma-Ray Bursts Observed with the FGST Gamma-Ray Burst Monitor

Abstract: From July 2008 to October 2009, the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope (FGST) has detected 320 Gamma-Ray Bursts (GRBs). About 20% of these events are classified as short based on their T90 duration below 2 s. We present here for the first time time-resolved spectroscopy at timescales as short as 2 ms for the three brightest short GRBs observed with GBM. The time-integrated spectra of the events deviate from the Band function, indicating the existence of an additional spectral component, which can be fit by a power-law with index ~-1.5. The time-integrated Epeak values exceed 2 MeV for two of the bursts, and are well above the values observed in the brightest long GRBs. Their Epeak values and their low-energy power-law indices ({\alpha}) confirm that short GRBs are harder than long ones. We find that short GRBs are very similar to long ones, but with light curves contracted in time and with harder spectra stretched towards higher energies. In our time-resolved spectroscopy analysis, we find that the Epeak values range from a few tens of keV up to more than 6 MeV. In general, the hardness evolutions during the bursts follows their flux/intensity variations, similar to long bursts. However, we do not always see the Epeak leading the light-curve rises, and we confirm the zero/short average light-curve spectral lag below 1 MeV, already established for short GRBs. We also find that the time-resolved low-energy power-law indices of the Band function mostly violate the limits imposed by the synchrotron models for both slow and fast electron cooling and may require additional emission processes to explain the data. Finally, we interpreted these observations in the context of the current existing models and emission mechanisms for the prompt emission of GRBs.

The Swift Gamma-Ray Burst Mission

Abstract: The Swift mission, scheduled for launch in 2004, is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is a first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more than 100 bursts yr � 1 and performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. The objectives are to (1) determine the origin of GRBs, (2) classify GRBs and search for new types, (3) study the interaction of the ultrarelativistic outflows of GRBs with their surrounding medium, and (4) use GRBs to study the early universe out to z >10. The mission is being developed by a NASA-led international collaboration. It will carry three instruments: a newgeneration wide-field gamma-ray (15‐150 keV) detector that will detect bursts, calculate 1 0 ‐4 0 positions, and trigger autonomous spacecraft slews; a narrow-field X-ray telescope that will give 5 00 positions and perform spectroscopy in the 0.2‐10 keV band; and a narrow-field UV/optical telescope that will operate in the 170‐ 600 nm band and provide 0B3 positions and optical finding charts. Redshift determinations will be made for most bursts. In addition to the primary GRB science, the mission will perform a hard X-ray survey to a sensitivity of � 1m crab (� 2;10 � 11 ergs cm � 2 s � 1 in the 15‐150 keV band), more than an order of magnitude better than HEAO 1 A-4. A flexible data and operations system will allow rapid follow-up observations of all types of

Multi-messenger observations of a binary neutron star merger

Abstract: On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of $\sim 1.7\,{\rm{s}}$ with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of ${40}_{-8}^{+8}$ Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 $\,{M}_{\odot }$. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at $\sim 40\,{\rm{Mpc}}$) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position $\sim 9$ and $\sim 16$ days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.

Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A

Abstract: On 2017 August 17, the gravitational-wave event GW170817 was observed by the Advanced LIGO and Virgo detectors, and the gamma-ray burst (GRB) GRB 170817A was observed independently by the Fermi Gamma-ray Burst Monitor, and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory. The probability of the near-simultaneous temporal and spatial observation of GRB 170817A and GW170817 occurring by chance is $5.0\times {10}^{-8}$. We therefore confirm binary neutron star mergers as a progenitor of short GRBs. The association of GW170817 and GRB 170817A provides new insight into fundamental physics and the origin of short GRBs. We use the observed time delay of $(+1.74\pm 0.05)\,{\rm{s}}$ between GRB 170817A and GW170817 to: (i) constrain the difference between the speed of gravity and the speed of light to be between $-3\times {10}^{-15}$ and $+7\times {10}^{-16}$ times the speed of light, (ii) place new bounds on the violation of Lorentz invariance, (iii) present a new test of the equivalence principle by constraining the Shapiro delay between gravitational and electromagnetic radiation. We also use the time delay to constrain the size and bulk Lorentz factor of the region emitting the gamma-rays. GRB 170817A is the closest short GRB with a known distance, but is between 2 and 6 orders of magnitude less energetic than other bursts with measured redshift. A new generation of gamma-ray detectors, and subthreshold searches in existing detectors, will be essential to detect similar short bursts at greater distances. Finally, we predict a joint detection rate for the Fermi Gamma-ray Burst Monitor and the Advanced LIGO and Virgo detectors of 0.1–1.4 per year during the 2018–2019 observing run and 0.3–1.7 per year at design sensitivity.

The physics of gamma-ray bursts

Abstract: Gamma-ray bursts (GRB's), short and intense pulses of low-energy $\ensuremath{\gamma}$ rays, have fascinated astronomers and astrophysicists since their unexpected discovery in the late sixties. During the last decade, several space missions---BATSE (Burst and Transient Source Experiment) on the Compton Gamma-Ray Observatory, BeppoSAX and now HETE II (High-Energy Transient Explorer)---together with ground-based optical, infrared, and radio observatories have revolutionized our understanding of GRB's, showing that they are cosmological, that they are accompanied by long-lasting afterglows, and that they are associated with core-collapse supernovae. At the same time a theoretical understanding has emerged in the form of the fireball internal-external shocks model. According to this model GRB's are produced when the kinetic energy of an ultrarelativistic flow is dissipated in internal collisions. The afterglow arises when the flow is slowed down by shocks with the surrounding circumburst matter. This model has had numerous successful predictions, like the predictions of the afterglow itself, of jet breaks in the afterglow light curve, and of the optical flash that accompanies the GRB's. This review focuses on the current theoretical understanding of the physical processes believed to take place in GRB's.

A very energetic supernova associated with the |[gamma]|-ray burst of 29 March 2003

Abstract: Over the past five years evidence has mounted that long-duration (greater than 2s) gamma-ray bursts (GRBs), the most brilliant of all astronomical explosions, signal the collapse of massive stars in our Universe. This evidence, originally based on the probable association of one unusual GRB with a supernova, now includes the association of GRBs with regions of massive star-formation in distant galaxies, tantalizing evidence of supernova-like light-curve 'bumps' in the optical afterglows of several bursts, and lines of freshly synthesized elements in the spectra of a few X-ray afterglows. These observations support, but do not yet conclusively validate, models based upon the deaths of massive stars, presumably associated with core collapse. Here we report evidence for a very energetic supernova (a hypernova), temporally and spatially coincident with a GRB at redshift z=0.1685. The timing of the supernova indicates that it exploded within a few days of the GRB, strongly suggesting that core-collapse events can give rise to GRBs. Amongst the GRB central engine models proposed to-date, the properties of this supernova thus favour the collapsar model.