Neutrino Oscillations, Lorentz/CPT Violation, and Dark Energy (2009)
Ando, Shin'ichiro, Kamionkowski, Marc, Mocioiu, Irina
If dark energy (DE) couples to neutrinos, then there may be apparent violations of Lorentz/CPT invariance in neutrino oscillations. The DE-induced Lorentz/CPT violation takes a specific form that...
Klein–Nishina Effects on Optically Thin Synchrotron and Synchrotron Self-Compton Spectrum (2009)
Nakar, Ehud, Ando, Shin'ichiro, Sari, Re'em
We present analytic approximations to the optically thin synchrotron and synchrotron self-Compton (SSC) spectra when Klein-Nishina (KN) effects are important and pair production and external...
Imprint of galaxy clustering in the cosmic gamma-ray background (2009)
Ando, Shin'ichiro, Pavlidou, Vasiliki
Star-forming galaxies are predicted to contribute considerably to the cosmic gamma-ray background (CGB) as they are confirmed gamma-ray emitters and are the most numerous population of gamma-ray...
Gamma-ray background anisotropy from Galactic dark matter substructure (2009)
Dark matter annihilation in Galactic substructure will imprint characteristic angular signatures on the all-sky map of the diffuse gamma-ray background. We study the gamma-ray background anisotropy...
The gamma-ray-flux PDF from galactic halo substructure (2009)
Lee, Samuel K., Ando, Shin'ichiro, Kamionkowski, Marc
One of the targets of the recently launched Fermi Gamma-ray Space Telescope is a diffuse gamma-ray background from dark-matter annihilation or decay in the Galactic halo. N-body simulations and...
Gamma-ray background anisotropy from galactic dark matter substructure (2009)
Dark matter annihilation in galactic substructure would imprint characteristic angular signatures on the all-sky map of the diffuse gamma-ray background. We study the gamma-ray background anisotropy...
Klein-Nishina Effects on Optically Thin Synchrotron and Synchrotron Self-Compton Spectrum (2009)
Nakar, Ehud, Ando, Shin'ichiro, Sari, Re'em
We present analytic approximations to the optically thin synchrotron and synchrotron self-Compton (SSC) spectra when Klein-Nishina (KN) effects are important and pair production and external...
Taoso, Marco, Ando, Shin'ichiro, Bertone, Gianfranco, Profumo, Stefano
Dark matter (DM) annihilation could in principle contribute to the diffuse cosmic gamma-ray background. While with standard assumptions for cosmological and particle physics parameters this...
Non-thermal neutrinos from supernovae leaving a magnetar (2008)
Horiuchi, Shunsaku, Suwa, Yudai, Takami, Hajime, Ando, Shin'ichiro, Sato, Katsuhiko
Under the fossil field hypothesis of the origin of magnetar magnetic fields, the magnetar inherits its magnetic field from its progenitor. We show that during the supernova of such a progenitor,...
GeV emission from prompt and afterglow phases of gamma-ray bursts (2008)
Ando, Shin'ichiro, Nakar, Ehud, Sari, Re'em
We investigate the GeV emission from gamma-ray bursts (GRBs) using the results from the Energetic Gamma Ray Experimental Telescope (EGRET) and in view of the Gamma-Ray Large Area Space Telescope...
GeV emission from prompt and afterglow phases of gamma-ray bursts (2008)
Ando, Shin'ichiro, Nakar, Ehud, Sari, Re'em
We investigate the GeV emission from gamma-ray bursts (GRBs) using the results from the Energetic Gamma Ray Experimental Telescope (EGRET) and in view of the Gamma-Ray Large Area Space Telescope...
Broadband Radiation from Primary Electrons in Very Energetic Supernovae (2008)
Ando, Shin'ichiro, Mészáros, Peter
A class of very energetic supernovae (hypernovae) is associated with long gamma-ray bursts, in particular with a less energetic but more frequent population of gamma-ray bursts. Hypernovae also...
Taoso, Marco, Ando, Shin'ichiro, Bertone, Gianfranco, Profumo, Stefano
Dark matter (DM) annihilation could in principle contribute to the diffuse cosmic gamma-ray back- ground (CGB). While with standard assumptions for cosmological and particle physics parameters this...
Can proper motions of dark-matter subhalos be detected? (2008)
Ando, Shin'ichiro, Kamionkowski, Marc, Lee, Samuel K., Koushiappas, Savvas M.
One of the goals of NASA's Fermi Gamma-ray Space Telescope (formerly GLAST) will be the detection of gamma rays from dark-matter annihilation in the Galactic halo. Theoretical arguments suggest that...
Core-Collapse Astrophysics with a Five-Megaton Neutrino Detector (2008)
Kistler, Matthew D., Yuksel, Hasan, Ando, Shin'ichiro, Beacom, John F., Suzuki, Yoichiro
The legacy of solar neutrinos suggests that large neutrino detectors should be sited underground. However, to instead go underwater bypasses the need to move mountains, allowing much larger contained...
The Gamma-Ray-Flux Probability Distribution Function from Galactic Halo Substructure (2008)
Lee, Samuel K., Ando, Shin'ichiro, Kamionkowski, Marc
One of the targets of the recently launched Fermi Gamma-ray Space Telescope is a diffuse gamma-ray background from dark-matter annihilation or decay in the Galactic halo. N-body simulations and...
Can proper motions of dark-matter subhalos be detected? (2008)
Ando, Shin'ichiro, Kamionkowski, Marc, Lee, Samuel K., Koushiappas, Savvas M.
One of the goals of NASA's Fermi Gamma-ray Space Telescope (formerly GLAST) will be detection of gamma rays from dark-matter annihilation in the Galactic halo. Theoretical arguments suggest that dark...
Broadband Radiation from Primary Electrons in Very Energetic Supernovae (2008)
Ando, Shin'ichiro, Meszaros, Peter
A class of very energetic supernovae (hypernovae) is associated with long gamma-ray bursts, in particular with a less energetic but more frequent population of gamma-ray bursts. Hypernovae also...
Non-thermal neutrinos from supernovae leaving a magnetar (2008)
Horiuchi, Shunsaku, Suwa, Yudai, Takami, Hajime, Ando, Shin'ichiro, Sato, Katsuhiko
Under the fossil field hypothesis of the origin of magnetar magnetic fields, the magnetar inherits its magnetic field from its progenitor. We show that during the supernova of such a progenitor,...
GeV Emission from Prompt and Afterglow Phases of Gamma-Ray Bursts (2008)
Ando, Shin'ichiro, Nakar, Ehud, Sari, Re'em
We investigate the GeV emission from gamma-ray bursts (GRBs), using the results from the Energetic Gamma Ray Experimental Telescope (EGRET), and in view of the Gamma-ray Large Area Space Telescope...
Ando, Shin'ichiro, Beacom, John F., Profumo, Stefano, Rainwater, David
As suggested by some extensions of the standard model of particle physics, dark matter may be a super-weakly-interacting lightest stable particle, while the next-to-lightest particle (NLP) is charged...
Gamma-ray probe of cosmic ray pressure in galaxy clusters and cosmological implications (2008)
Ando, Shin'ichiro, Nagai, Daisuke
Cosmic rays produced in cluster accretion and merger shocks provide pressure to the intracluster medium (ICM) and affect the mass estimates of galaxy clusters. Although direct evidence for cosmic ray...
High-energy neutrinos from reverse shocks in choked and successful relativistic jets (2008)
Horiuchi, Shunsaku, Ando, Shin'ichiro
Highly relativistic jets are a key element of current gamma-ray burst models, where the jet kinetic energy is converted to radiation energy at optically thin shocks. High-energy neutrinos are also...
Nonlinear Evolution of Anisotropic Cosmological Power (2008)
Ando, Shin'ichiro, Kamionkowski, Marc
There has been growing interest in the possibility of testing more precisely the assumption of statistical isotropy of primordial density perturbations. If it is to be tested with galaxy surveys at...
Neutrino constraints on the dark matter total annihilation cross section (2007)
Yüksel, Hasan, Horiuchi, Shunsaku, Beacom, John F., Ando, Shin'ichiro
In the indirect detection of dark matter through its annihilation products, the signals depend on the square of the dark matter density, making precise knowledge of the distribution of dark matter in...
Ando, Shin'ichiro, Beacom, John F., Profumo, Stefano, Rainwater, David
As suggested by some extensions of the Standard Model of particle physics, dark matter may be a super-weakly interacting lightest stable particle, while the next-to-lightest particle (NLP) is charged...
High-energy neutrinos from reverse shocks in choked and successful relativistic jets (2007)
Horiuchi, Shunsaku, Ando, Shin'ichiro
Highly relativistic jets are a key element of current gamma-ray burst models, where the jet kinetic energy is converted to radiation energy at optically thin shocks. High-energy neutrinos are also...
Nonlinear Evolution of Anisotropic Cosmological Power (2007)
Ando, Shin'ichiro, Kamionkowski, Marc
There has been growing interest in the possibility of testing more precisely the assumption of statistical isotropy of primordial density perturbations. If it is to be tested with galaxy surveys at...
Neutrino Constraints on the Dark Matter Total Annihilation Cross Section (2007)
Yuksel, Hasan, Horiuchi, Shunsaku, Beacom, John F., Ando, Shin'ichiro
In the indirect detection of dark matter through its annihilation products, the signals depend on the square of the dark matter density, making precise knowledge of the distribution of dark matter in...
Gamma-ray probe of cosmic-ray pressure in galaxy clusters and cosmological implications (2007)
Ando, Shin'ichiro, Nagai, Daisuke
Cosmic rays produced in cluster accretion and merger shocks provide pressure to the intracluster medium (ICM) and affect the mass estimates of galaxy clusters. Although direct evidence for cosmic-ray...
Angular power spectrum of gamma-ray sources for GLAST: blazars and clusters of galaxies (2007)
Ando, Shin'ichiro, Komatsu, Eiichiro, Narumoto, Takuro, Totani, Tomonori
Blazars, a beamed population of active galactic nuclei, radiate high-energy γ-rays, and thus are a good target for the Gamma Ray Large Area Space Telescope (GLAST). As the blazars trace the...
Ando, Shin'ichiro, Komatsu, Eiichiro, Narumoto, Takuro, Totani, Tomonori
The origin of the cosmic gamma-ray background (CGB) is a longstanding mystery in high-energy astrophysics. Possible candidates include ordinary astrophysical objects such as unresolved blazars, as...
Cosmic gamma-ray background from dark matter annihilation (2007)
High-energy photons from pair annihilation of dark matter particles contribute to the cosmic gamma-ray background (CGB) observed in a wide energy range. The precise shape of the energy spectrum of...
Ando, Shin'ichiro, Komatsu, Eiichiro, Narumoto, Takuro, Totani, Tomonori
The origin of the cosmic gamma-ray background (CGB) is a longstanding mystery in high-energy astrophysics. Possible candidates include ordinary astrophysical objects such as unresolved blazars, as...
Horiuchi, Shunsaku, Ando, Shin'ichiro
We investigate contributions to the extragalactic gamma-ray background (EGB) due to neutralino dark matter (DM) pair-annihilation into photons, from DM density enhancements (minispikes) surrounding...
Angular power spectrum of gamma-ray sources for GLAST: blazars and clusters of galaxies (2006)
Ando, Shin'ichiro, Komatsu, Eiichiro, Narumoto, Takuro, Totani, Tomonori
Blazars, a beamed population of active galactic nuclei, radiate high-energy gamma-rays, and thus are a good target for the Gamma Ray Large Area Space Telescope (GLAST). As the blazars trace the...
Horiuchi, Shunsaku, Ando, Shin'ichiro
We investigate contributions to the extragalactic gamma-ray background (EGB) due to neutralino dark matter (DM) pair-annihilation into photons, from DM density enhancements (minispikes) surrounding...
Anisotropy of the cosmic gamma-ray background from dark matter annihilation (2005)
Ando, Shin'ichiro, Komatsu, Eiichiro
High-energy photons from dark matter annihilation contribute to the cosmic gamma-ray background (CGB). Since dark matter particles are weakly interacting, annihilation can happen only in high density...
Yuksel, Hasan, Ando, Shin'ichiro, Beacom, John
The time-integrated luminosity and average energy of the neutrino emission spectrum are essential diagnostics of core-collapse supernovae. The SN 1987A electron antineutrino observations by the...
Detection of Neutrinos from Supernovae in Nearby Galaxies (2005)
Ando, Shin'ichiro, Beacom, John F., Yuksel, Hasan
While existing detectors would see a burst of many neutrinos from a Milky Way supernova, the supernova rate is only a few per century. As an alternative, we propose the detection of ~ 1 neutrino per...
Can Dark Matter Annihilation Dominate the Extragalactic Gamma-Ray Background? (2005)
Annihilating dark matter (DM) has been discussed as a possible source of gamma-rays from the galactic center (GC) and contributing to the extragalactic gamma-ray background (EGB). Assuming...
Revealing the Supernova--Gamma-Ray Burst Connection with TeV Neutrinos (2005)
Ando, Shin'ichiro, Beacom, John F.
Gamma-ray bursts (GRBs) are rare but powerful explosions displaying highly relativistic jets. It has been suggested that a significant fraction of the much more frequent core-collapse supernovae are...
Relic neutrino background from cosmological supernovae (2004)
Ando, Shin'ichiro, Sato, Katsuhiko
Present and future observations of supernova relic neutrinos (SRNs), i.e., a cosmological neutrino background from past core-collapse supernova explosions, potentially give us useful information...
Does regenerated emission change the high-energy signal from gamma-ray burst afterglows? (2004)
We study regenerated high-energy emission from the gamma-ray burst (GRB) afterglows, and compare its flux with the direct component from the same afterglow. When the intrinsic emission spectrum...
Short gamma-ray bursts as a possible probe of binary neutron star mergers (2004)
We study the properties of short gamma-ray bursts (GRBs), based on the assumption that they are all connected to the binary neutron star mergers, whose formation mechanism contains a large amount of...
Appearance of neutronization peak and decaying supernova neutrinos (2004)
Nonradiative neutrino decay, which is not satisfactorily constrained, possibly and significantly changes the detected neutrino signal from galactic supernova explosions. We focus on the appearance of...
Cosmic Star Formation History and the Future Observation of Supernova Relic Neutrinos (2004)
We investigate the flux and event rate of supernova relic neutrinos (SRNs) and discuss their implications for the cosmic star formation rate. As reference models, we adopt the supernova rate model...
Ando, Shin'ichiro, Sato, Katsuhiko
Resonant spin-flavour (RSF) conversions of supernova neutrinos, which is induced by the interaction between the nonzero neutrino magnetic moment and supernova magnetic fields, are studied for both...
Decaying neutrinos and implications from the supernova relic neutrino observation (2003)
We propose that supernova relic neutrino (SRN) observation can be used to set constraints on the neutrino decay models. Because of the long distance scale from cosmological supernovae to the Earth,...
Asymmetric neutrino emission due to neutrino-nucleon scatterings in supernova magnetic fields (2003)
We derive the cross section of neutrino-nucleon scatterings in supernova magnetic fields, including weak-magnetism and recoil corrections. Since the weak interaction violates the parity, the...
Ando, Shin'ichiro, Sato, Katsuhiko
We study the resonant spin-flavor (RSF) conversion of supernova neutrinos, which is induced by the interaction between the nonzero neutrino magnetic moment and the supernova magnetic fields, and its...
Ando, Shin'ichiro, Sato, Katsuhiko
We investigate resonant spin-flavor (RSF) conversions of supernova neutrinos which are induced by the interaction of neutrino magnetic moment and supernova magnetic fields. From the formulation which...
Supernova relic neutrinos and observational implications for neutrino oscillation (2002)
Ando, Shin'ichiro, Sato, Katsuhiko
We investigate the flux of supernova relic neutrinos (SRN) for several neutrino oscillation models with parameters inferred from recent experimental results. In the calculation, we adopt the...
Determining the Supernova Direction by its Neutrinos (2001)
Ando, Shin'ichiro, Sato, Katsuhiko
Supernova neutrinos, which arrive at Earth earlier than light, allow for the earliest determination of the direction of the supernova. The topic of this paper is to study how accurately we can...