D. H. Hartmann
A5062138157- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- SAS software applications and methods
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Nuclear Physics and Applications
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- Neutrino Physics Research
- Radio Astronomy Observations and Technology
- Solar and Space Plasma Dynamics
- Particle Accelerators and Free-Electron Lasers
- Astrophysics and Star Formation Studies
- Statistical and numerical algorithms
- Planetary Science and Exploration
- History and Developments in Astronomy
- Advanced X-ray and CT Imaging
- Laser-Plasma Interactions and Diagnostics
- Nuclear physics research studies
Clemson University
2015-2024
Southeastern Universities Research Association
2020-2024
Marshall Space Flight Center
2008-2024
Observatoire de la Côte d’Azur
2024
Universidad Católica Santo Domingo
2023
Berkeley College
2023
University of California, Berkeley
2008-2023
Universities Space Research Association
2008-2021
University of Alabama in Huntsville
2009-2021
Oxfam
2021
How massive stars die—what sort of explosion and remnant each produces—depends chiefly on the masses their helium cores hydrogen envelopes at death. For single stars, stellar winds are only means mass loss, these a function metallicity star. We discuss how metallicity, simplified prescription for its effect affects evolution final fate stars. map, as where black holes neutron likely to form different types supernovae produced. Integrating over an initial function, we derive relative...
view Abstract Citations (636) References (98) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The nu -Process Woosley, S. E. ; Hartmann, D. H. Hoffman, R. Haxton, W. C. As the core of a massive star collapses to form neutron star, flux neutrinos in overlying shells heavy elements becomes so great that, despite small cross section, substantial nuclear transmutation is induced. Neutrinos excite and even helium particle unbound levels. evaporation single or...
We present a catalog of sources detected above 50 GeV by the {\it Fermi}-Large Area Telescope (LAT) in 80 months data. The newly delivered Pass 8 event-level analysis allows detection and characterization GeV--2 TeV energy range. In this band, Fermi}-LAT has 360 sources, which constitute second hard (2FHL). improved angular resolution enables precise localization point ($\sim$1.7$'$ radius at 68 % C.~L.) spatially extended sources. find that 86 can be associated with counterparts other...
With the first direct detection of merging black holes in 2015, era gravitational wave (GW) astrophysics began. A complete picture compact object mergers, however, requires an electromagnetic (EM) counterpart. We report ultraviolet (UV) and X-ray observations by Swift Nuclear Spectroscopic Telescope ARray (NuSTAR) EM counterpart binary neutron star merger GW170817. The bright, rapidly fading emission indicates a high mass ($\approx0.03$ solar masses) wind-driven outflow with moderate...
The origin of the extragalactic $\gamma$-ray background (EGB) has been debated for some time. { EGB comprises emission from resolved and unresolved sources, such as blazars, star-forming galaxies radio galaxies, well radiation truly diffuse processes.} This letter focuses on blazar source class, most numerous detected population, presents an updated luminosity function spectral energy distribution model consistent with observations performed by {\it Fermi} Large Area Telescope (LAT). We show...
We report the discovery of unusually bright long-duration gamma-ray burst (GRB), GRB 221009A, as observed by Neil Gehrels Swift Observatory (Swift), Monitor All-sky X-ray Image (MAXI), and Neutron Star Interior Composition Explorer Mission (NICER). This energetic was located relatively nearby (z = 0.151), allowing for sustained observations afterglow. The large luminosity low Galactic latitude (b 4.3 degrees) make 221009A a powerful probe dust in Milky Way. Using echo tomography we map...
The mergers of binary compact objects such as neutron stars and black holes are central interest to several areas astrophysics, including the progenitors gamma-ray bursts (GRBs), sources high-frequency gravitational waves likely production sites for heavy element nucleosynthesis via rapid capture (the r-process). These elements include some great geophysical, biological cultural importance, thorium, iodine gold. Here we present observations exceptionally bright burst GRB 230307A. We show...
The cosmological origin of at least an appreciable fraction classical gamma-ray bursts (GRBs) is now supported by redshift measurements for a half-dozen faint host galaxies. Still, the nature central engine (or engines) that provide burst energy remains unclear. While many models have been proposed, those currently favored are all based upon formation and/or rapid accretion into stellar-mass black holes. Here we discuss variety such scenarios and estimate probability each. Population...
Bearing on the model for time-dependent metagalactic radiation field developed in first paper of this series, we compute gamma-ray attenuation due to pair production photon-photon scattering. Emphasis is effects varying star formation rate and fraction UV assumed escape from forming regions, latter being important mainly high-redshift sources. Conversely, investigate how can be measured creation cutoff as a function redshift, Fazio-Stecker relation. For three observed TeV-blazars (Mkn 501,...
view Abstract Citations (184) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Search for Important Weak Interaction Nuclei in Presupernova Evolution Aufderheide, Maurice B. ; Fushiki, Ikko Woosley, Stanford E. Hartmann, Dieter H. A search is made the most important electron captures and beta-decays after core silicon burning massive stars. nuclear statistical equilibrium code used to compute isotopic abundances. Electron capture beta-decay...
view Abstract Citations (189) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Nucleosynthesis in Neutron-rich Supernova Ejecta Hartmann, D. ; Woosley, S. E. El Eid, M. F. is studied supernova ejecta that achieve nuclear statistical equilibrium with a characteristic neutron excess far greater than customarily assigned to the production of most abundant heavy elements. A small amount such material will copiously produce very neutron-rich...
We report on the detection by Swift of GRB 080913, and subsequent optical/near-infrared follow-up observations GROND, which led to discovery its optical/NIR afterglow recognition high-z nature via a spectral break between i' z' bands. Spectroscopy obtained at ESO-VLT revealed continuum extending down λ = 9400 Å, zero flux for 7500 Å<λ < we interpret as onset Gunn–Peterson trough z 6.695± 0.025 (95.5% confidence level), making 080913 highest-redshift gamma-ray burst (GRB) date, more distant...
Context. Thirteen years after the discovery of first afterglows, nature dark gamma-ray bursts (GRB) still eludes explanation: while each long-duration GRB typically has an X-ray afterglow, optical/NIR emission is only seen for 40–60% them.
Aims.We present early optical spectroscopy of the afterglow gamma-ray burst GRB 060206 with aim determining metallicity absorber and physical conditions in circumburst medium. We also discuss how GRBs may be important complementary probes cosmic chemical evolution.
Gamma rays reveal the Universe's history How many stars have formed in Universe, and when did they do so? These fundamental questions are difficult to answer because there systematic uncertainties converting light we observe into total mass of galaxies. The Fermi-LAT Collaboration addressed these by exploiting way that gamma from distant blazars propagate through intergalactic space, which depends on amount emitted all collaboration found star formation peaked about 3 billion years after Big...
The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that will provide essential contributions to multimessenger astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity 200 keV 10 GeV energy range with wide field of view, good spectral resolution, polarization sensitivity. Therefore, key study astrophysical objects have unique signatures gamma-ray regime, such as neutron star mergers, supernovae, flaring active galactic nuclei....
The All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X) is designed to identify and characterize gamma rays from extreme explosions accelerators. main science themes include: supermassive black holes their connections neutrinos cosmic rays; binary neutron star mergers the relativistic jets they produce; ray particle acceleration sources including Galactic supernovae; continuous monitoring of other astrophysical events over full sky in this important energy range. AMEGO-X will...