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Title: TeV Gamma Rays From Galactic Center Pulsars

Abstract

Measurements of the nearby pulsars Geminga and B0656+14 by the HAWC and Milagro telescopes have revealed the presence of bright TeV-emitting halos surrounding these objects. If young and middle-aged pulsars near the Galactic Center transfer a similar fraction of their energy into TeV photons, then these sources could dominate the emission that is observed by HESS and other ground-based telescopes from the innermost ~10^2 parsecs of the Milky Way. In particular, both the spectral shape and the angular extent of this emission is consistent with TeV halos produced by a population of pulsars. The overall flux of this emission requires a birth rate of ~100-1000 neutron stars per Myr near the Galactic Center, in good agreement with recent estimates.

Authors:
ORCiD logo [1];  [2];  [3]
  1. Fermilab
  2. Johns Hopkins U.
  3. Ohio State U., CCAPP
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1367901
Report Number(s):
FERMILAB-PUB-17-173-A; arXiv:1705.09293
1601359
DOE Contract Number:
AC02-07CH11359
Resource Type:
Journal Article
Resource Relation:
Journal Name: TBD
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Hooper, Dan, Cholis, Ilias, and Linden, Tim. TeV Gamma Rays From Galactic Center Pulsars. United States: N. p., 2017. Web.
Hooper, Dan, Cholis, Ilias, & Linden, Tim. TeV Gamma Rays From Galactic Center Pulsars. United States.
Hooper, Dan, Cholis, Ilias, and Linden, Tim. Thu . "TeV Gamma Rays From Galactic Center Pulsars". United States. doi:. https://www.osti.gov/servlets/purl/1367901.
@article{osti_1367901,
title = {TeV Gamma Rays From Galactic Center Pulsars},
author = {Hooper, Dan and Cholis, Ilias and Linden, Tim},
abstractNote = {Measurements of the nearby pulsars Geminga and B0656+14 by the HAWC and Milagro telescopes have revealed the presence of bright TeV-emitting halos surrounding these objects. If young and middle-aged pulsars near the Galactic Center transfer a similar fraction of their energy into TeV photons, then these sources could dominate the emission that is observed by HESS and other ground-based telescopes from the innermost ~10^2 parsecs of the Milky Way. In particular, both the spectral shape and the angular extent of this emission is consistent with TeV halos produced by a population of pulsars. The overall flux of this emission requires a birth rate of ~100-1000 neutron stars per Myr near the Galactic Center, in good agreement with recent estimates.},
doi = {},
journal = {TBD},
number = ,
volume = ,
place = {United States},
year = {Thu May 25 00:00:00 EDT 2017},
month = {Thu May 25 00:00:00 EDT 2017}
}
  • The Galactic Center has been observed with the CANGAROO-II imaging atmospheric Cherenkov telescope in 2001 and 2002. We detected a statistically significant excess at energies greater than 250GeV. This is the first detection of sub-TeV gamma rays from the Galactic Center region. The signal direction is consistent with the Galactic Center, which includes the massive black hole Sgr A* and supernova remnant Sgr A East. The resultant flux is 1 order of magnitude lower than that of the Crab Nebula at 1 TeV. The differential flux has a steep spectrum and the power law index is observed to be -4.6more » {+-} 0.5, although it could flatten to -3.4 if the uncertainty in energy determination is included. Here, the analysis for reduction of night sky background effects and the radiation mechanism of sub-TeV gamma rays are reported. The most probable radiation mechanism is {pi}0 decays. The maximum energy of the inferred cosmic rays is 1-3 TeV and the total cosmic-ray luminosity corresponds to 1 {approx} 10 supernova remnants. We also obtain an upper limit on the cold dark matter density in the galactic halo.« less
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  • Using the Tibet-III air shower array, we search for TeV {gamma}-rays from 27 potential Galactic sources in the early list of bright sources obtained by the Fermi Large Area Telescope at energies above 100 MeV. Among them, we observe seven sources instead of the expected 0.61 sources at a significance of 2{sigma} or more excess. The chance probability from Poisson statistics would be estimated to be 3.8 x 10{sup -6}. If the excess distribution observed by the Tibet-III array has a density gradient toward the Galactic plane, the expected number of sources may be enhanced in chance association. Then, themore » chance probability rises slightly, to 1.2 x 10{sup -5}, based on a simple Monte Carlo simulation. These low chance probabilities clearly show that the Fermi bright Galactic sources have statistically significant correlations with TeV {gamma}-ray excesses. We also find that all seven sources are associated with pulsars, and six of them are coincident with sources detected by the Milagro experiment at a significance of 3{sigma} or more at the representative energy of 35 TeV. The significance maps observed by the Tibet-III air shower array around the Fermi sources, which are coincident with the Milagro {>=}3{sigma} sources, are consistent with the Milagro observations. This is the first result of the northern sky survey of the Fermi bright Galactic sources in the TeV region.« less