NYCB Real Time Computing Inc.

Lattingtown, NY, United States

NYCB Real Time Computing Inc.

Lattingtown, NY, United States

Time filter

Source Type

Ackermann M.,German Electron Synchrotron | Albert A.,Kavli Institute for Particle Astrophysics and Cosmology | Anderson B.,Albanova University Center | Anderson B.,The Oskar Klein Center | And 169 more authors.
Physical Review Letters | Year: 2015

The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass 100 GeV annihilating via quark and τ-lepton channels. © 2015 American Physical Society.


Ackermann M.,German Electron Synchrotron | Ajello M.,Clemson University | Albert A.,Kavli Institute for Particle Astrophysics and Cosmology | Atwood W.B.,University of California at Santa Cruz | And 184 more authors.
Astrophysical Journal | Year: 2015

The γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse γ-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi ) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission (DGE), and a longer data accumulation of 50 months allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 ± 0.02 and a break energy of (279 ± 52) GeV using our baseline DGE model. The total intensity attributed to the IGRB is (7.2 ± 0.6) x 10-6 cm-2 s-1 sr-1 above 100 MeV, with an additional +15%/-30% systematic uncertainty due to the Galactic diffuse foregrounds. © 2015. The American Astronomical Society. All rights reserved.


Ackermann M.,Kavli Institute for Particle Astrophysics and Cosmology | Ajello M.,Kavli Institute for Particle Astrophysics and Cosmology | Albert A.,Ohio State University | Atwood W.B.,University of California at Santa Cruz | And 187 more authors.
Physical Review Letters | Year: 2011

Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10 -26cmm 3s -1 at 5 GeV to about 5×10 -23cm 3s -1 at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (∼3×10 -26cm 3s -1 for a purely s-wave cross section), without assuming additional boost factors. © 2011 American Physical Society.


Ackermann M.,German Electron Synchrotron | Ajello M.,Kavli Institute for Particle Astrophysics and Cosmology | Allafort A.,Kavli Institute for Particle Astrophysics and Cosmology | Atwood W.B.,University of California at Santa Cruz | And 188 more authors.
Physical Review Letters | Year: 2012

We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting Earth's shadow, which is offset in opposite directions for opposite charges due to Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 and 200 GeV. We confirm that the fraction rises with energy in the 20-100 GeV range. The three new spectral points between 100 and 200 GeV are consistent with a fraction that is continuing to rise with energy. © 2012 American Physical Society.


Ackermann M.,German Electron Synchrotron | Albert A.,Kavli Institute for Particle Astrophysics and Cosmology | Anderson B.,Albanova University Center | Anderson B.,The Oskar Klein Center | And 150 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via γ rays. Here we report on γ-ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in γ rays, and we present γ-ray flux upper limits between 500 MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. We set some of the tightest constraints to date on the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical standard model channels. We find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse γ-ray background modeling, and assumed dark matter density profile. © 2014 American Physical Society.


Ackermann M.,Kavli Institute for Particle Astrophysics and Cosmology | Ajello M.,Kavli Institute for Particle Astrophysics and Cosmology | Allafort A.,Kavli Institute for Particle Astrophysics and Cosmology | Baldini L.,National Institute of Nuclear Physics, Italy | And 209 more authors.
Astrophysical Journal Letters | Year: 2014

The detection of diffuse radio emission associated with clusters of galaxies indicates populations of relativistic leptons infusing the intraclustermedium (ICM). Those electrons and positrons are either injected into and accelerated directly in the ICM, or produced as secondary pairs by cosmic-ray ions scattering on ambient protons. Radiation mechanisms involving the energetic leptons together with the decay of neutral pions produced by hadronic interactions have the potential to produce abundant GeV photons. Here, we report on the search for GeV emission from clusters of galaxies using data collected by the Large Area Telescope on the FermiGamma-ray Space Telescope from 2008 August to 2010 February. Thirty-three galaxy clusters have been selected according to their proximity and high mass, X-ray flux and temperature, and indications of non-thermal activity for this study. We report upper limits on the photon flux in the range 0.2-100GeVtoward a sample of observed clusters (typical values (1-5)×10-9 photon cm-2 s-1) considering both point-like and spatially resolved models for the high-energy emission and discuss how these results constrain the characteristics of energetic leptons and hadrons, and magnetic fields in the ICM. The volume-averaged relativistic-hadron-to-thermal energy density ratio is found to be <5%-10% in several clusters. © 2010. The American Astronomical Society. All rights reserved.


PubMed | German Electron Synchrotron, Montpellier University, Fermi National Accelerator Laboratory, University of Rome Tor Vergata and 31 more.
Type: Journal Article | Journal: Physical review letters | Year: 2015

The dwarf spheroidal satellite galaxies (dSphs) of the MilkyWay are some of the most dark matter (DM) dominated objects known. We report on -ray observations of MilkyWay dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass 100GeV annihilating via quark and -lepton channels.

Loading NYCB Real Time Computing Inc. collaborators
Loading NYCB Real Time Computing Inc. collaborators