skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: THE SPECTRUM OF ISOTROPIC DIFFUSE GAMMA-RAY EMISSION BETWEEN 100 MeV AND 820 GeV

Abstract

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 IGRBmore » is (7.2 ± 0.6) × 10{sup –6} cm{sup –2} s{sup –1} sr{sup –1} above 100 MeV, with an additional +15%/–30% systematic uncertainty due to the Galactic diffuse foregrounds.« less

Authors:
;  [1];  [2]; ; ; ; ;  [3];  [4]; ;  [5];  [6];  [7]; ;  [8];  [9];  [10];  [11];  [12];
  1. Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany)
  2. Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634-0978 (United States)
  3. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
  4. Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States)
  5. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
  6. Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d'Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France)
  7. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
  8. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
  9. Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States)
  10. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, and Università di Trieste, I-34127 Trieste (Italy)
  11. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  12. Laboratoire Univers et Particules de Montpellier, Université Montpellier 2, CNRS/IN2P3, F-34095 Montpellier (France)
Publication Date:
OSTI Identifier:
22364446
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; COSMIC GAMMA SOURCES; GAMMA RADIATION; GEV RANGE; INDEXES; MEV RANGE; MILKY WAY; PHOTON EMISSION; SPACE; TELESCOPES

Citation Formats

Ackermann, M., Buehler, R., Ajello, M., Albert, A., Blandford, R. D., Bloom, E. D., Bottacini, E., Caliandro, G. A., Atwood, W. B., Baldini, L., Bellazzini, R., Ballet, J., Barbiellini, G., Bastieri, D., Buson, S., Bechtol, K., Bissaldi, E., Brandt, T. J., Bregeon, J., Bruel, P., E-mail: markus.ackermann@desy.de, E-mail: bechtol@kicp.uchicago.edu, and others, and. THE SPECTRUM OF ISOTROPIC DIFFUSE GAMMA-RAY EMISSION BETWEEN 100 MeV AND 820 GeV. United States: N. p., 2015. Web. doi:10.1088/0004-637X/799/1/86.
Ackermann, M., Buehler, R., Ajello, M., Albert, A., Blandford, R. D., Bloom, E. D., Bottacini, E., Caliandro, G. A., Atwood, W. B., Baldini, L., Bellazzini, R., Ballet, J., Barbiellini, G., Bastieri, D., Buson, S., Bechtol, K., Bissaldi, E., Brandt, T. J., Bregeon, J., Bruel, P., E-mail: markus.ackermann@desy.de, E-mail: bechtol@kicp.uchicago.edu, & others, and. THE SPECTRUM OF ISOTROPIC DIFFUSE GAMMA-RAY EMISSION BETWEEN 100 MeV AND 820 GeV. United States. https://doi.org/10.1088/0004-637X/799/1/86
Ackermann, M., Buehler, R., Ajello, M., Albert, A., Blandford, R. D., Bloom, E. D., Bottacini, E., Caliandro, G. A., Atwood, W. B., Baldini, L., Bellazzini, R., Ballet, J., Barbiellini, G., Bastieri, D., Buson, S., Bechtol, K., Bissaldi, E., Brandt, T. J., Bregeon, J., Bruel, P., E-mail: markus.ackermann@desy.de, E-mail: bechtol@kicp.uchicago.edu, and others, and. 2015. "THE SPECTRUM OF ISOTROPIC DIFFUSE GAMMA-RAY EMISSION BETWEEN 100 MeV AND 820 GeV". United States. https://doi.org/10.1088/0004-637X/799/1/86.
@article{osti_22364446,
title = {THE SPECTRUM OF ISOTROPIC DIFFUSE GAMMA-RAY EMISSION BETWEEN 100 MeV AND 820 GeV},
author = {Ackermann, M. and Buehler, R. and Ajello, M. and Albert, A. and Blandford, R. D. and Bloom, E. D. and Bottacini, E. and Caliandro, G. A. and Atwood, W. B. and Baldini, L. and Bellazzini, R. and Ballet, J. and Barbiellini, G. and Bastieri, D. and Buson, S. and Bechtol, K. and Bissaldi, E. and Brandt, T. J. and Bregeon, J. and Bruel, P., E-mail: markus.ackermann@desy.de, E-mail: bechtol@kicp.uchicago.edu and others, and},
abstractNote = {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) × 10{sup –6} cm{sup –2} s{sup –1} sr{sup –1} above 100 MeV, with an additional +15%/–30% systematic uncertainty due to the Galactic diffuse foregrounds.},
doi = {10.1088/0004-637X/799/1/86},
url = {https://www.osti.gov/biblio/22364446}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 799,
place = {United States},
year = {Tue Jan 20 00:00:00 EST 2015},
month = {Tue Jan 20 00:00:00 EST 2015}
}

Works referencing / citing this record:

Discovering and Locating High-Energy Extra-galactic Sources by Bayesian Mixture Modelling
book, August 2019


A composite model for the 750 GeV diphoton excess
journal, March 2016


Active galactic nuclei: what’s in a name?
journal, August 2017


The e-ASTROGAM mission: Exploring the extreme Universe with gamma rays in the MeV – GeV range
journal, June 2017


Background for a gamma-ray satellite on a low-Earth orbit
journal, March 2019


The Giant Radio Array for Neutrino Detection (GRAND): Science and design
journal, August 2019


A survey of dark matter and related topics in cosmology
journal, October 2016


Coincidence of a high-fluence blazar outburst with a PeV-energy neutrino event
journal, April 2016


High-energy neutrino astrophysics
journal, July 2016


Multi-messenger astrophysics
journal, October 2019


The denoised, deconvolved, and decomposed Fermi γ -ray sky : An application of the D
journal, September 2015


Deep view of the Large Magellanic Cloud with six years of Fermi -LAT observations
journal, January 2016


Searching for γ -ray signature in WHSP blazars
journal, February 2017


Second AGILE catalogue of gamma-ray sources
journal, June 2019


Galactic diffuse gamma-ray emission at TeV energy
journal, January 2020


High-energy cosmic neutrino puzzle: a review
journal, October 2015


TOMOGRAPHY OF THE FERMI -LAT γ -RAY DIFFUSE EXTRAGALACTIC SIGNAL VIA CROSS CORRELATIONS WITH GALAXY CATALOGS
journal, March 2015


CONFRONTING GALACTIC AND EXTRAGALACTIC γ -RAYS OBSERVED BY FERMI -LAT WITH ANNIHILATING DARK MATTER IN AN INERT HIGGS DOUBLET MODEL
journal, August 2015


Dark Matter Searches in the Gamma-Ray Extragalactic Background via Cross-Correlations with Galaxy Catalogs
journal, December 2015


Tomographic-spectral approach for dark matter detection in the cross-correlation between cosmic shear and diffuse γ-ray emission
journal, June 2015


Limits on dark matter annihilation signals from the Fermi LAT 4-year measurement of the isotropic gamma-ray background
journal, September 2015


Constraining particle dark matter using local galaxy distribution
journal, June 2016


Heavy right-handed neutrino dark matter and PeV neutrinos at IceCube
journal, August 2016


A case for radio galaxies as the sources of IceCube's astrophysical neutrino flux
journal, September 2016


Fermi-LAT kills dark matter interpretations of AMS-02 data. Or not?
journal, January 2017


A combined astrophysical and dark matter interpretation of the IceCube HESE and throughgoing muon events
journal, July 2018


Searching for dark matter annihilation from individual halos: uncertainties, scatter and signal-to-noise ratios
journal, August 2018


Neutrinophilic Dark Matter in the epoch of IceCube and Fermi-LAT
journal, December 2018


Active galactic nuclei and the origin of IceCube's diffuse neutrino flux
journal, February 2019


Constraints on decaying dark matter from the isotropic gamma-ray background
journal, March 2019


Gamma-rays from possible disk component of dark matter
journal, January 2017


Ultrahard spectra of PeV neutrinos from supernovae in compact star clusters
journal, August 2015


Imprints of cosmic rays in multifrequency observations of the interstellar emission
journal, December 2017


Cross-correlation of weak lensing and gamma rays: implications for the nature of dark matter
journal, February 2017


The galactic isotropic γ-ray background and implications for dark matter
journal, June 2018


Extreme- and high-synchrotron-peaked blazars at the limit of Fermi-LAT detectability: the γ-ray spectrum of 1BIGB sources
journal, July 2018


Extragalactic gamma-ray background from star-forming galaxies: Will empirical scalings suffice?
journal, December 2018


Radio background and IGM heating due to Pop III supernova explosions
journal, December 2018


New synthesis models of consistent extragalactic background light over cosmic time
journal, January 2019


Gamma-ray luminosity function of BL Lac objects and contribution to the extragalactic gamma-ray background
journal, September 2019


Searching for gamma-ray emission from galaxy clusters at low redshift
journal, November 2019


Acceleration and propagation of ultra-high energy cosmic rays
journal, November 2017


Extragalactic background light measurements and applications
journal, March 2016


Multimessenger tests of cosmic-ray acceleration in radiatively inefficient accretion flows
journal, October 2019


Primordial black holes as silver bullets for new physics at the weak scale
journal, December 2019


Realistic estimation for the detectability of dark matter subhalos using Fermi-LAT catalogs
journal, September 2017


Modeling evolution of dark matter substructure and annihilation boost
journal, June 2018


Correlation of extragalactic γ rays with cosmic matter density distributions from weak gravitational lensing
journal, June 2018


Detection of Cross-Correlation between Gravitational Lensing and γ Rays
journal, March 2020


Carpet-2 Search for PeV Gamma Rays Associated with IceCube High-Energy Neutrino Events
journal, February 2019


Gamma-ray astrophysics
journal, August 2018


Development of dark disk model of positron anomaly origin
journal, April 2018


Indirect effects of dark matter
journal, October 2019


An interpretation of the cosmic ray e+ + e− spectrum from 10GeV to 3TeV measured by CALET on the ISS
journal, January 2019


The Spectrum of the Universe
journal, February 2018


Constraints on decaying dark matter from the extragalactic gamma-ray background
text, January 2015


IceCube neutrinos from hadronically powered gamma-ray galaxies
text, January 2019


Open Questions in Cosmic-Ray Research at Ultrahigh Energies
journal, June 2019


Evidence against Star-forming Galaxies as the Dominant Source of Icecube Neutrinos
journal, February 2017


KASCADE-Grande Limits on the Isotropic Diffuse Gamma-Ray Flux between 100 TeV and 1 EeV
journal, October 2017


Bow Ties in the Sky. II. Searching for Gamma-Ray Halos in the Fermi Sky Using Anisotropy
journal, November 2017


Ships Passing in the Night: Spectroscopic Analysis of Two Ultra-faint Satellites in the Constellation Carina
journal, April 2018


Cumulative Neutrino and Gamma-Ray Backgrounds from Halo and Galaxy Mergers
journal, April 2018


Transient High-energy Gamma-Rays and Neutrinos from Nearby Type II Supernovae
journal, February 2019


The Extragalactic Gamma-Ray Background from Core-dominated Radio Galaxies
journal, July 2019


Deciphering Residual Emissions: Time-dependent Models for the Nonthermal Interstellar Radiation from the Milky Way
journal, December 2019


CROSS-CORRELATING THE γ -RAY SKY WITH CATALOGS OF GALAXY CLUSTERS
journal, January 2017


Signatures of Intra-binary Shock Emission in the Black Widow Pulsar Binary PSR J2241−5236
journal, November 2018


Fermi -LAT Stacking Analysis Technique: An Application to Extreme Blazars and Prospects for their CTA Detection
journal, August 2019


High-Energy Neutrino Astrophysics
book, December 2018


IceCube neutrinos from hadronically powered gamma-ray galaxies
journal, September 2019


Constraints on dark matter annihilation and decay from the isotropic gamma-ray background
journal, April 2017


Modeling evolution of dark matter substructure and annihilation boost
journal, February 2020


Contribution of starburst nuclei to the diffuse gamma-ray and neutrino flux
journal, March 2020


Measurement of redshift-dependent cross-correlation of HSC clusters and Fermi γ-rays
journal, February 2019


Testing the Dark Matter Scenario for PeV Neutrinos Observed in IceCube
journal, August 2015


Measurement of cosmic-ray electrons at TeV energies by VERITAS
text, January 2018


Fermi-LAT Stacking Analysis Technique: An Application to Extreme Blazars and Prospects for their CTA Detection
text, January 2019


Constraints on Gamma-Ray and Neutrino Emission from NGC 1068 with the MAGIC Telescopes
text, January 2019


SED Constraints on the Highest- z Blazar Jet: QSO J0906+6930
journal, March 2018


Ultrahard spectra of PeV neutrinos from supernovae in compact star clusters
text, January 2015


The Fermi-LAT GeV excess as a tracer of stellar mass in the Galactic bulge
journal, August 2018


Constraints on decaying dark matter from the extragalactic gamma-ray background
journal, May 2015


Carpet-2 Search for pev Gamma rays Associated with Icecube High-Energy Neutrino Events
journal, January 2019

  • Dzhappuev, D. D.; Dzaparova, I. M.; Gorbacheva, E. A.
  • ПИСЬМА В ЖУРНАЛ ЭКСПЕРИМЕНТАЛЬНОЙ И ТЕОРЕТИЧЕСКОЙ ФИЗИКИ, Vol. 109, Issue 3-4
  • https://doi.org/10.1134/s0370274x19040039

Constraints on Ultrahigh-Energy Cosmic-Ray Sources from a Search for Neutrinos above 10 PeV with IceCube
text, January 2016


The e-ASTROGAM mission
text, January 2017


Unresolved Gamma-Ray Sky through its Angular Power Spectrum
text, January 2018


Open Questions in Cosmic-Ray Research at Ultrahigh Energies
text, January 2019


Gamma-ray astrophysics
journal, August 1983


Search for dark matter annihilations towards the inner Galactic halo from 10 years of observations with H.E.S.S
text, January 2016


Acceleration and Propagation of Ultra High Energy Cosmic Rays
conference, January 2005


Resolving the Extragalactic $\gamma$-Ray Background above 50 GeV with the Fermi Large Area Telescope
text, January 2016


Open Questions in Cosmic-Ray Research at Ultrahigh Energies
text, January 2019


Constraints on Gamma-Ray and Neutrino Emission from NGC 1068 with the MAGIC Telescopes
journal, September 2019


Testing the Dark Matter Scenario for PeV Neutrinos Observed in IceCube
text, January 2015


WIMP searches with gamma rays in the Fermi era: challenges, methods and results
text, January 2015


IceCube neutrinos, decaying dark matter, and the Hubble constant
text, January 2015


A Composite Model for the 750 GeV Diphoton Excess
text, January 2016


Heavy right-handed neutrino dark matter and PeV neutrinos at IceCube
text, January 2016


Testing decay of astrophysical neutrinos with incomplete information
text, January 2016


Active Galactic Nuclei: what's in a name?
text, January 2017


Cumulative Neutrino and Gamma-Ray Backgrounds from Halo and Galaxy Mergers
text, January 2017


Unexpected Dip in the Solar Gamma-Ray Spectrum
text, January 2018


Neutrinophilic Dark Matter in the epoch of IceCube and Fermi-LAT
text, January 2018


The Giant Radio Array for Neutrino Detection (GRAND): Science and Design
text, January 2018


The Extragalactic Gamma-Ray Background from Core Dominated Radio Galaxies
text, January 2019


Searching for gamma-ray emission from galaxy clusters at low redshift
text, January 2019


Breaking a dark degeneracy: The gamma-ray signature of early matter domination
text, January 2019