S. W. Digel
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View article: Report of the Topical Group on Dark Energy and Cosmic Acceleration: Complementarity of Probes and New Facilities for Snowmass 2021
Report of the Topical Group on Dark Energy and Cosmic Acceleration: Complementarity of Probes and New Facilities for Snowmass 2021 Open
The mechanism(s) driving the early- and late-time accelerated expansion of the Universe represent one of the most compelling mysteries in fundamental physics today. The path to understanding the causes of early- and late-time acceleration …
View article: Incremental Fermi Large Area Telescope Fourth Source Catalog
Incremental Fermi Large Area Telescope Fourth Source Catalog Open
We present an incremental version (4FGL-DR3, for Data Release 3) of the fourth Fermi Large Area Telescope (LAT) catalog of γ -ray sources. Based on the first 12 years of science data in the energy range from 50 MeV to 1 TeV, it contains 66…
View article: A gamma-ray pulsar timing array constrains the nanohertz gravitational wave background
A gamma-ray pulsar timing array constrains the nanohertz gravitational wave background Open
After large galaxies merge, their central supermassive black holes are expected to form binary systems. Their orbital motion should generate a gravitational wave background (GWB) at nanohertz frequencies. Searches for this background use p…
View article: Unveiling the Fermi Bubbles origin with MeV photon telescopes
Unveiling the Fermi Bubbles origin with MeV photon telescopes Open
The Fermi Bubbles (FB) are a pair of large-scale ellipsoidal structures extending above and below the Galactic plane almost symmetrically aligned with the Galactic Center. After more than 10 years since their discovery, their nature and or…
View article: Catalog of Long-term Transient Sources in the First 10 yr of Fermi-LAT Data
Catalog of Long-term Transient Sources in the First 10 yr of Fermi-LAT Data Open
We present the first Fermi Large Area Telescope (LAT) catalog of long-term γ -ray transient sources (1FLT). This comprises sources that were detected on monthly time intervals during the first decade of Fermi-LAT operations. The monthly ti…
View article: Fermi Large Area Telescope Fourth Source Catalog
Fermi Large Area Telescope Fourth Source Catalog Open
We present the fourth Fermi Large Area Telescope catalog (4FGL) of γ -ray sources. Based on the first eight years of science data from the Fermi Gamma-ray Space Telescope mission in the energy range from 50 MeV to 1 TeV, it is the deepest …
View article: All-sky Medium Energy Gamma-ray Observatory: Exploring the Extreme Multimessenger Universe
All-sky Medium Energy Gamma-ray Observatory: Exploring the Extreme Multimessenger Universe Open
The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class\nmission concept that will provide essential contributions to multimessenger\nastrophysics in the late 2020s and beyond. AMEGO combines high sensitivity in\nthe 200 k…
View article: All-sky Medium Energy Gamma-ray Observatory: Exploring the Extreme Multimessenger Universe
All-sky Medium Energy Gamma-ray Observatory: Exploring the Extreme Multimessenger Universe Open
The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that will provide essential contributions to multimessenger astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity in the 200 keV …
View article: Fermi Large Area Telescope Fourth Source Catalog
Fermi Large Area Telescope Fourth Source Catalog Open
We present the fourth Fermi Large Area Telescope catalog (4FGL) of gamma-ray sources. Based on the first eight years of science data from the Fermi Gamma-ray Space Telescope mission in the energy range from 50 MeV to 1 TeV, it is the deepe…
View article: Unresolved Gamma-Ray Sky through its Angular Power Spectrum
Unresolved Gamma-Ray Sky through its Angular Power Spectrum Open
The gamma-ray sky has been observed with unprecedented accuracy in the last decade by the Fermi -large area telescope (LAT), allowing us to resolve and understand the high-energy Universe. The nature of the remaining unresolved emission [u…
View article: Fermi-LAT improved Pass~8 event selection
Fermi-LAT improved Pass~8 event selection Open
The current version of the Fermi Large Area Telescope data (P8R2) has been publicly available since June 2015, with the caveat that the residual background of all event classes, except ULTRACLEANVETO, was not fully isotropic: it was enhanc…
View article: Erratum: “Search for Gamma-Ray Emission from the Coma Cluster with Six Years of Fermi-LAT Data” (2016, ApJ, 819, 149)
Erratum: “Search for Gamma-Ray Emission from the Coma Cluster with Six Years of Fermi-LAT Data” (2016, ApJ, 819, 149) Open
The naming of the sources in Tables 3 and 4 in the Appendix of the published paper did not follow IAU conventions; the corrected nomenclature will enter the NASA Extragalactic Database. Tables 3 and 4 should thus read as follows. (Table Pr…
View article: Search for Gamma-Ray Emission from Local Primordial Black Holes with the Fermi Large Area Telescope
Search for Gamma-Ray Emission from Local Primordial Black Holes with the Fermi Large Area Telescope Open
Black holes with masses below approximately 10 15 g are expected to emit gamma-rays with energies above a few tens of MeV, which can be detected by the Fermi Large Area Telescope (LAT). Although black holes with these masses cannot be form…
View article: Einstein@Home discovers a radio-quiet gamma-ray millisecond pulsar
Einstein@Home discovers a radio-quiet gamma-ray millisecond pulsar Open
Millisecond pulsars (MSPs) are old neutron stars that spin hundreds of times per second and appear to pulsate as their emission beams cross our line of sight. To date, radio pulsations have been detected from all rotation-powered MSPs. In …
View article: 3FHL: The Third Catalog of Hard Fermi-LAT Sources
3FHL: The Third Catalog of Hard Fermi-LAT Sources Open
We present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in the first 7 years of data using the Pass 8 event-level analysis. This is the Third Catalog of Hard Fermi -LAT Sources (3FHL), containing 1556 …
View article: Fermi Observations of the LIGO Event GW170104
Fermi Observations of the LIGO Event GW170104 Open
We present the Fermi Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) observations of the LIGO binary black hole merger (BBH) event GW170104. No candidate electromagnetic counterpart was detected by either GBM or LAT. A detaile…
View article: A Search for Cosmic-ray Proton Anisotropy with the Fermi Large Area Telescope
A Search for Cosmic-ray Proton Anisotropy with the Fermi Large Area Telescope Open
The Fermi Large Area Telescope (LAT) has amassed a large data set of primary cosmic-ray protons throughout its mission. In fact, it is the largest set of identified cosmic-ray protons ever collected at this energy. The LAT's wide field of …
View article: The Fermi Galactic Center GeV Excess and Implications for Dark Matter
The Fermi Galactic Center GeV Excess and Implications for Dark Matter Open
The region around the Galactic Center (GC) is now well established to be brighter at energies of a few GeV than what is expected from conventional models of diffuse gamma-ray emission and catalogs of known gamma-ray sources. We study the G…
View article: Characterizing the population of pulsars in the inner Galaxy with the Fermi Large Area Telescope
Characterizing the population of pulsars in the inner Galaxy with the Fermi Large Area Telescope Open
An excess of $γ$-ray emission from the Galactic Center (GC) region with respect to predictions based on a variety of interstellar emission models and $γ$-ray source catalogs has been found by many groups using data from the {\it Fermi} Lar…
View article: Cosmic-ray electron-positron spectrum from 7 GeV to 2 TeV with the Fermi Large Area Telescope
Cosmic-ray electron-positron spectrum from 7 GeV to 2 TeV with the Fermi Large Area Telescope Open
We present a measurement of the cosmic-ray electron+positron spectrum between 7 GeV and 2 TeV performed with almost seven years of data collected with the Fermi Large Area Telescope. We find that the spectrum is well fit by a broken power …
View article: Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope Data
Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope Data Open
The Large Area Telescope on board the Fermi Gamma-ray Space Telescope has collected the largest ever sample of high-energy cosmic-ray electron and positron events since the beginning of its operation. Potential anisotropies in the arrival …
View article: Gamma-Ray Blazars within the First 2 Billion Years
Gamma-Ray Blazars within the First 2 Billion Years Open
The detection of high-redshift ( ) blazars enables the study of the evolution of the most luminous relativistic jets over cosmic time. More importantly, high-redshift blazars tend to host massive black holes and can be used to constrain th…
View article: Observations of M31 and M33 with the Fermi Large Area Telescope: A Galactic Center Excess in Andromeda?
Observations of M31 and M33 with the Fermi Large Area Telescope: A Galactic Center Excess in Andromeda? Open
The Fermi Large Area Telescope (LAT) has opened the way for comparative studies of cosmic rays (CRs) and high-energy objects in the Milky Way (MW) and in other, external, star-forming galaxies. Using 2 yr of observations with the Fermi LAT…
View article: Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares
Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares Open
We report on the Fermi -LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi -LAT observations are associated with flares from act…
View article: SEARCHING THE GAMMA-RAY SKY FOR COUNTERPARTS TO GRAVITATIONAL WAVE SOURCES: FERMI GAMMA-RAY BURST MONITOR AND LARGE AREA TELESCOPE OBSERVATIONS OF LVT151012 AND GW151226
SEARCHING THE GAMMA-RAY SKY FOR COUNTERPARTS TO GRAVITATIONAL WAVE SOURCES: FERMI GAMMA-RAY BURST MONITOR AND LARGE AREA TELESCOPE OBSERVATIONS OF LVT151012 AND GW151226 Open
We present the Fermi Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) observations of the LIGO binary black hole merger event GW151226 and candidate LVT151012. At the time of the LIGO triggers on LVT151012 and GW151226, GBM was…
View article: Tracing the propagation of cosmic rays in the Milky Way halo with Fermi-LAT observations of high- and intermediate-velocity c
Tracing the propagation of cosmic rays in the Milky Way halo with Fermi-LAT observations of high- and intermediate-velocity c Open
Cosmic rays up to at least PeV energies are usually described in the framework of an elementary scenario that involves acceleration by objects that are located in the disk of the Milky Way, such as supernova remnants or massive star-formin…
View article: FERMI LARGE AREA TELESCOPE DETECTION OF EXTENDED GAMMA-RAY EMISSION FROM THE RADIO GALAXY FORNAX A
FERMI LARGE AREA TELESCOPE DETECTION OF EXTENDED GAMMA-RAY EMISSION FROM THE RADIO GALAXY FORNAX A Open
We report the Fermi Large Area Telescope detection of extended γ -ray emission from the lobes of the radio galaxy Fornax A using 6.1 years of Pass 8 data. After Centaurus A, this is now the second example of an extended γ -ray source attri…
View article: MINUTE-TIMESCALE >100 MeV γ-RAY VARIABILITY DURING THE GIANT OUTBURST OF QUASAR 3C 279 OBSERVED BY FERMI-LAT IN 2015 JUNE
MINUTE-TIMESCALE >100 MeV γ-RAY VARIABILITY DURING THE GIANT OUTBURST OF QUASAR 3C 279 OBSERVED BY FERMI-LAT IN 2015 JUNE Open
On 2015 June 16, Fermi -LAT observed a giant outburst from the flat spectrum radio quasar 3C 279 with a peak >100 MeV flux of ∼3.6 × 10 −5 photons cm −2 s −1 , averaged over orbital period intervals. It is historically the highest γ -ray f…