Razzaque, Soebur, Dermer, Charles D., Finke, Justin D.
Fermi gamma-ray telescope data of GRB 080916C with ~1e55 erg in apparent isotropic gamma-ray energy, show a several second delay between the rise of 100 MeV - GeV radiation compared with keV - MeV...
Modeling the Extragalactic Background Light from Stars and Dust (2009)
Finke, Justin D., Razzaque, Soebur, Dermer, Charles D.
The extragalactic background light (EBL) from the far infrared through the visible and extending into the ultraviolet is thought to be dominated by starlight, either through direct emission or...
Finke, Justin D., Razzaque, Soebur
The extragalactic background light (EBL) from the infrared to the ultraviolet is difficult to measure directly, but can be constrained with a variety of methods. EBL photons absorb gamma-rays from...
Observational Consequences of GRBs as Sources of Ultra High Energy Cosmic Rays (2009)
Razzaque, Soebur, Dermer, Charles D., Finke, Justin D., Atoyan, Armen
Gamma-ray bursts (GRBs) have long been considered as candidates of ultrahigh-energy cosmic rays (UHECRs). We investigate the signatures of CR proton acceleration in the GRBs by consistently taking...
Razzaque, Soebur, Mena, Olga, Dermer, Charles D.
Protons accelerated in the internal shocks of a long duration gamma ray burst can escape the fireball as cosmic rays by converting to neutrons. Hadronic interactions of these neutrons inside a...
Razzaque, Soebur, Dermer, Charles D., Finke, Justin D.
TeV gamma rays from distant astrophysical sources are attenuated due to electron-positron pair creation by interacting with ultraviolet/optical to infrared photons which fill the universe and are...
Neutrino mass hierarchy extraction using atmospheric neutrinos in ice (2008)
Mena, Olga, Mocioiu, Irina, Razzaque, Soebur
We show that the measurements of 10 GeV atmospheric neutrinos by an upcoming array of densely packed phototubes buried deep inside the IceCube detector at the South Pole can be used to determine the...
On the Origin and Survival of UHE Cosmic-Ray Nuclei in GRBs and Hypernovae (2007)
Wang, Xiang-Yu, Razzaque, Soebur, Meszaros, Peter
The chemical composition of the ultra-high-energy (UHE) cosmic rays serves as an important clue for their origin. Recent measurements of the elongation rates by the Pierre Auger Observatory hint at...
Ultrahigh-energy neutrino flux as a probe of large extra-dimensions (2007)
Lykken, Joseph, Mena, Olga, Razzaque, Soebur
A suppression in the spectrum of ultrahigh-energy (UHE, >= 10^{18} eV) neutrinos will be present in extra-dimensional scenarios, due to enhanced neutrino-antineutrino annihilation processes with the...
High-energy Cosmic Rays and Neutrinos from Semi-relativistic Hypernovae (2007)
Wang, Xiang-Yu, Razzaque, Soebur, Meszaros, Peter, Dai, Zi-Gao
The origin of the ultrahigh-energy (UHE) cosmic rays (CRs) from the second knee ($\sim6\times10^{17}$eV) above in the CR spectrum is still unknown. Recently, there has been growing evidence that a...
Oscillation effects on high-energy neutrino fluxes from astrophysical hidden sources (2006)
Mena, Olga, Mocioiu, Irina, Razzaque, Soebur
High-energy neutrinos are expected to be produced in a vareity of astrophysical sources as well as in optically thick hidden sources. We explore the matter-induced oscillation effects on emitted...
Beta decay radiation signature from neutron-rich gamma-ray bursts? (2006)
Razzaque, Soebur, Meszaros, Peter
Core collapse of massive stars and binary neutron stars or black hole-neutron star binary mergers are likely progenitors of long and short duration gamma-ray bursts respectively. Neutronized material...
MeV-GeV emission from neutron-loaded short gamma-ray burst jets (2006)
Razzaque, Soebur, Meszaros, Peter
Recent discovery of the afterglow emission from short gamma-ray bursts suggests that binary neutron star or black hole-neutron star binary mergers are the likely progenitors of these short bursts....
High energy neutrinos from a slow jet model of core collapse supernovae (2005)
Razzaque, Soebur, Meszaros, Peter, Waxman, Eli
It has been hypothesized recently that core collapse supernovae are triggered by mildly relativistic jets following observations of radio properties of these explosions. Association of a jet, similar...
Razzaque, Soebur, Meszaros, Peter, Waxman, Eli
The ratio of anti-electron to total neutrino flux, $\Phi_{\bar{\nu}_e}:\Phi_\nu$, expected from $p\gamma$ interactions in astrophysical sources is $\le1:15$. We point out that this ratio is enhanced...
TeV-PeV Neutrinos from Giant Flares of Magnetars and the Case of SGR 1806-20 (2005)
Ioka, Kunihito, Razzaque, Soebur, Kobayashi, Shiho, Meszaros, Peter
We estimate the high energy neutrino flux from the giant flare of SGR 1806-20 on December 27, 2004, which irradiated Earth with a gamma-ray flux ~10^4 times larger than the most luminous gamma-ray...
GeV and higher energy photon interactions in gamma-ray burst fireballs and surroundings (2004)
Razzaque, Soebur, Meszaros, Peter, Zhang, Bing
We have calculated the opacities and secondary production mechanisms of high energy photons arising in gamma-ray burst internal shocks, using exact cross-sections for the relevant processes. We find...
Neutrino signatures of the supernova - gamma ray burst relationship (2003)
Razzaque, Soebur, Meszaros, Peter, Waxman, Eli
We calculate the TeV-PeV neutrino fluxes of gamma-ray bursts associated with supernovae, based on the observed association between GRB 030329 and supernova SN 2003dh. The neutrino spectral flux...
Neutrino Tomography of Gamma Ray Bursts and Massive Stellar Collapses (2003)
Razzaque, Soebur, Meszaros, Peter, Waxman, Eli
Neutrinos at energies above TeV can serve as probes of the stellar progenitor and jet dynamics of gamma ray bursts arising from stellar core collapses. They can also probe collapses which do not lead...
High Energy Neutrinos from Gamma-Ray Bursts with Precursor Supernovae (2002)
Razzaque, Soebur, Meszaros, Peter, Waxman, Eli
The high energy neutrino signature from proton-proton and photo-meson interactions in a supernova remnant shell ejected prior to a gamma-ray burst provides a test for the precursor supernova, or...
Ultra-High Energy Quenching of the LPM Effect: Implications for GZK-Violating Events (2002)
Ralston, John P., Razzaque, Soebur, Jain, Pankaj
Cosmic rays in the regime of 10^19-10^20 eV should not exist, according to the GZK bound. Conflicts between data and the bound have led to suggestions that laws of physics must be modified. We find...
Coherence effects in ultrahigh energy electromagnetic interactions with matter / (2002)
Thesis (Ph. D.)--University of Kansas, Physics and Astronomy, 2002.
Coherent Radio Pulses From GEANT Generated Electromagnetic Showers In Ice (2001)
Razzaque, Soebur, Seunarine, Surujhdeo, Besson, David Z., McKay, Douglas W., Ralston, John P., Seckel, David
Radio Cherenkov radiation is arguably the most efficient mechanism for detecting showers from ultra-high energy particles of 1 PeV and above. Showers occuring in Antarctic ice should be detectable at...
On the Global Anisotropy of Cosmic Ray Data above $4 \times 10^{19}eV$ (2001)
Razzaque, Soebur, Ralston, John P.
The distribution of arrival directions of ultra-high energy cosmic rays may yield clues to their mysterious origin. We introduce a method of {\it invariant statistics} to analyze cosmic ray data...
Signal Characteristics from Electromagnetic Cascades in Ice (2001)
Razzaque, Soebur, Seunarine, Surujhdeo, Besson, David Z., McKay, Douglas W.
We investigate the development of electromagnetic cascades in ice using a GEANT Monte Carlo simulation. We examine the Cherenkov pulse that is generated by the charge excess that develops and...
Correlation of Ultra High Energy Cosmic Rays with Compact Radio Loud Quasars (2000)
Virmani, Amitabh, Bhattacharya, Sibesh, Jain, Pankaj, Razzaque, Soebur, Ralston, John P., McKay, Douglas W.
Angular correlations of ultra-high energy cosmic rays with cosmologically distant sources may provide clues to these mysterious events. We compare cosmic ray tracks with energies above $ 10^{20}eV$...