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The Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope provides an unprecedented opportunity to study gamma-ray blazars. To capitalize on this opportunity, beginning in late 2007, about a year before the start of LAT…

The Fermi-Large Area Telescope (LAT) First Source Catalog (1FGL) was released in February 2010 and the Fermi-LAT 2-Year Source Catalog (2FGL) appeared in April 2012, based on data from 24 months of operation. Since their releases, many…

We study a sample of 30 high-redshift blazars ($z>2.5$) by means of spectra and the radiation mechanism with Fermi Large Area Telescope $\gamma$-ray observations spanning 15 years. Three models -- the power law, power law with an…

高能天体物理现象 · 物理学 2025-01-27 Fan Wu , Benzhong Dai

The sensitivity of the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope allows detection of thousands of new gamma-ray sources and detailed characterization of the spectra and variability of bright sources.…

天体物理仪器与方法 · 物理学 2015-03-18 Matthew Kerr

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…

高能天体物理现象 · 物理学 2025-06-04 Matteo Cerruti

Extragalactic globular clusters (GCs) are important tracers of galaxy formation and evolution. Obtaining GC catalogues from photometric data involves several steps which will likely become too time-consuming to perform on the large data…

星系天体物理 · 物理学 2022-07-20 Dominik Dold , Katja Fahrion

We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the ~30% of gamma-ray sources in the Fermi 2FGL…

We present the results of a search for high-energy gamma-ray emission from a large sample of galaxy clusters sharing the properties of three existing Fermi-LAT detections (in Perseus, Virgo and Abell 3392), namely a powerful radio source…

高能天体物理现象 · 物理学 2015-06-12 K. L. Dutson , R. J. White , A. C. Edge , J. A. Hinton , M. T. Hogan

We present an updated version catalogue of gamma-ray source candidates, 12Y-MST, selected using the minimum spanning tree (MST) algorithm on the 12-year Fermi-LAT sky (Pass 8) at energies higher than 10 GeV. The high-energy sky at absolute…

高能天体物理现象 · 物理学 2021-08-11 R. Campana , E. Massaro

The Third Catalog of Hard Fermi Large Area Telescope Sources (3FHL) reports the detection of 1556 objects at E > 10 GeV. However, 177 sources remain unassociated and 23 are associated with a ROSAT X-ray detection of unknown origin. Pointed…

高能天体物理现象 · 物理学 2022-12-07 S. Joffre , R. Silver , M. Rajagopal , M. Ajello , N. Torres-Albà , A. Pizzetti , S. Marchesi , A. Kaur

Recent detection of suborbital gamma-ray variability of Flat Spectrum Radio Quasar (FSRQ) 3C 279 by Fermi Large Area Telescope (LAT) is in severe conflict with established models of blazar emission. This paper presents the results of…

高能天体物理现象 · 物理学 2017-12-15 Krzysztof Nalewajko

We present a novel spectral machine learning (SML) method in screening for pancreatic mass using CT imaging. Our algorithm is trained with approximately 30,000 images from 250 patients (50 patients with normal pancreas and 200 patients with…

计算机视觉与模式识别 · 计算机科学 2021-05-04 Yiming Liu , Ying Chen , Guangming Pan , Weichung Wang , Wei-Chih Liao , Yee Liang Thian , Cheng E. Chee , Constantinos P. Anastassiades

Bolometric luminosity is a basic physical parameter that is widely used in the study of blazars. Due to the lack of simultaneous full wavelength data, several estimators of the bolometric luminosity are being used in practice. In this…

高能天体物理现象 · 物理学 2017-10-04 Zerui Wang , Rui Xue , Leiming Du , Zhaohua Xie , Dingrong Xiong , Tingfeng Yi , Yunbing Xu , Wenguang Liu

We report on HET and Palomar 5 m spectroscopy of recently identified $\gamma$-ray blazars in the {\it Fermi} LAT Bright Source List. These data provide identifications for 10 newly discovered $\gamma$-ray flat spectrum radio quasars (FSRQ)…

We study the $\gamma$-ray and broadband spectral energy distribution (SED) properties of a complete sample of 104 bright, radio-selected low-synchrotron peaked (LSP) blazars. Most of the sources have already been detected in the…

高能天体物理现象 · 物理学 2018-08-08 B. Arsioli , G. Polenta

Tensions between the diffuse gamma-ray sky observed by the Fermi Large Area Telescope (LAT) and the diffuse high-energy neutrino sky detected by the IceCube South Pole Neutrino Observatory question our knowledge about high-energy neutrino…

高能天体物理现象 · 物理学 2023-11-01 Emma Kun , Imre Bartos , Julia Becker Tjus , Peter L. Biermann , Anna Franckowiak , Francis Halzen , György Mező

We present a likelihood profile stacking technique based on the {\it Fermi}-Large Area Telescope (LAT) data to explore the $\gamma$-ray characteristics of {\it Fermi}-LAT undetected astrophysical populations. The pipeline is applied to a…

高能天体物理现象 · 物理学 2019-09-10 Vaidehi S. Paliya , Alberto Dominguez , Marco Ajello , Anna Franckowiak , Dieter Hartmann

Photometric variability detection is often considered as a hypothesis testing problem: an object is variable if the null-hypothesis that its brightness is constant can be ruled out given the measurements and their uncertainties. Uncorrected…

天体物理仪器与方法 · 物理学 2018-01-25 Ilya N. Pashchenko , Kirill V. Sokolovsky , Panagiotis Gavras

Breast cancer is not preventable because of its unknown causes. However, its early diagnosis increases patients' recovery chances. Machine learning (ML) can be utilized to improve treatment outcomes in healthcare operations while…

机器学习 · 计算机科学 2024-08-09 Kamyab Karimi , Ali Ghodratnama , Reza Tavakkoli-Moghaddam

Blazars are among the most studied sources in high-energy astrophysics as they form the largest fraction of extragalactic gamma-ray sources and are considered prime candidates for being the counterparts of high-energy astrophysical…