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A large fraction of Fermi-Large Area Telescope (LAT) sources in the fourth Fermi-LAT 14 yr catalog (4FGL) still remain unidentified (unIDed). We continued to improve our machine-learning pipeline and used it to classify 1206 X-ray sources…

High Energy Astrophysical Phenomena · Physics 2024-08-20 Hui Yang , Jeremy Hare , Oleg Kargaltsev

We have searched for ultra-long (> 100 s) gamma-ray transients in the data from the anticoincidence shield (ACS) of the SPI gamma-ray spectrometer onboard the INTEGRAL orbital observatory and classified them by machine learning methods. We…

The primary challenge in the study of explosive astrophysical transients is their detection and characterisation using multiple messengers. For this purpose, we have developed a new data-driven discovery framework, based on deep learning.…

High Energy Astrophysical Phenomena · Physics 2020-05-14 Iftach Sadeh

The Fermi Large Area Telescope (Fermi LAT) provides long term systematic monitoring observations of the gamma-ray emission from blazars. The variability properties and the correlation with other wavelength bands are important clues for the…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Stefan Larsson

We present results from the first two years of our fast-cadence 15 GHz gamma-ray blazar monitoring program, part of the F-GAMMA radio monitoring project. Our sample includes the 1158 blazars north of -20 degrees declination from the…

We present evidence for $\gamma$-ray emission from a stacked population of 39 high-latitude globular clusters (GCs) not detected in the Fermi Point Source Catalog, likely attributable to populations of millisecond pulsars within them. In…

High Energy Astrophysical Phenomena · Physics 2024-10-17 Owen K. Henry , Timothy A. D. Paglione , Yuzhe Song , Joshua Tan , David Zurek , Vanessa Pinto

Blazars are the most common sources of $\gamma$-ray photons in the extragalactic sky. Their $\gamma$-ray light curves are characterized by bright flaring episodes, similarly to what is observed at longer wavelengths. These gamma-ray bursts…

High Energy Astrophysical Phenomena · Physics 2025-06-04 Matteo Cerruti

Since the launch of the Fermi gamma - ray Space Telescope on June 11, 2008, the LAT instrument has solidly detected more than 20 GRBs with high energy photon emission above 100 MeV. Using the matched filter technique, 3 more GRBs have also…

High Energy Astrophysical Phenomena · Physics 2012-01-19 WeiKang Zheng , Carl W. Akerlof , Shashi B. Pandey , Timothy A. McKay , BinBin Zhang , Bing Zhang

We describe the optical spectropolarimetric monitoring program at Steward Observatory centered around gamma-ray-bright blazars and the LAT Monitored Source List planned for Fermi Cycles 2-4. The large number of measurements made during…

High Energy Astrophysical Phenomena · Physics 2009-12-21 P. S. Smith , E. Montiel , S. Rightley , J. Turner , G. D. Schmidt , B. T. Jannuzi

The Fermi Large Area Telescope (LAT) is a powerful pulsar detector, as demonstrated by the over one hundred objects in its second catalog of pulsars. Pass 8 is a new reconstruction and event selection strategy developed by the Fermi-LAT…

High Energy Astrophysical Phenomena · Physics 2019-08-14 H. Laffon , D. A. Smith , L. Guillemot

This catalog summarizes 117 high-confidence > 0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data, through…

High Energy Astrophysical Phenomena · Physics 2013-09-25 LAT collaboration

One of the scientific objectives of NASA's Fermi Gamma-ray Space Telescope is the study of Gamma-Ray Bursts (GRBs). The Fermi Gamma-Ray Burst Monitor (GBM) was designed to detect and localize bursts for the Fermi mission. By means of an…

In this work, we propose a deep learning-based classification model of astronomical objects using alerts reported by the Zwicky Transient Facility (ZTF) survey. The model takes as inputs sequences of stamp images and metadata contained in…

Instrumentation and Methods for Astrophysics · Physics 2024-05-27 Daniel Neira O. , Pablo A. Estévez , Francisco Förster

Modern astronomical surveys, such as the Zwicky Transient Facility (ZTF), are capable of detecting thousands of transient events per year, necessitating the use of automated and scalable data analysis techniques. Recent advances in machine…

Instrumentation and Methods for Astrophysics · Physics 2025-04-17 Betty X. Hu , Avi Loeb

The Fermi-LAT unassociated sources represent some of the most enigmatic gamma-ray sources in the sky. Observations with the Swift-XRT and -UVOT telescopes have identified hundreds of likely X-ray and UV/optical counterparts in the…

Supervised classification of temporal sequences of astronomical images into meaningful transient astrophysical phenomena has been considered a hard problem because it requires the intervention of human experts. The classifier uses the…

Instrumentation and Methods for Astrophysics · Physics 2020-10-07 Catalina Gómez , Mauricio Neira , Marcela Hernández Hoyos , Pablo Arbeláez , Jaime E. Forero-Romero

The Fermi Flare Advocate (also known as Gamma-ray Sky Watcher, FA-GSW) service provides for a daily quicklook analysis and review of the high-energy gamma-ray sky seen by the Fermi Gamma-ray Space Telescope. The duty offers alerts for…

High Energy Astrophysical Phenomena · Physics 2019-08-15 S. Ciprini , D. Gasparrini , D. Bastieri , J. Chiang , G. Tosti

Macrolensing of gamma-ray bursts (GRBs) is expected to manifest as a GRB recurring with the same light curve and spectrum as a previous one, but with a different flux and a slightly offset position. Identifying such lensed GRBs may give…

High Energy Astrophysical Phenomena · Physics 2020-07-22 Björn Ahlgren , Josefin Larsson

The accurate spatial location of gamma-ray bursts (GRBs) is crucial for both producing a detector response matrix (DRM) and follow-up observations by other instruments. The Fermi Gamma-ray Burst Monitor (GBM) has the largest field of view…

Instrumentation and Methods for Astrophysics · Physics 2016-10-25 J. Michael Burgess , Hoi-Fung Yu , Jochen Greiner , Daniel J. Mortlock

GRB170817A, associated with the LIGO-Virgo GW170817 neutron-star merger event, lacks the short duration and hard spectrum of a Short gamma-ray burst (GRB) expected from long-standing classification models. Correctly identifying the class to…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-14 I. Horvath , B. G. Toth , J. Hakkila , L. V. Toth , L. G. Balazs , I. I. Racz , S. Pinter , Z. Bagoly
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