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Although not designed primarily as a polarimeter, the \textit{Fermi}-Large Area Telescope (LAT) has the potential to detect high degrees of linear polarization from some of the brightest gamma-ray sources. To achieve the needed accuracy in…

Instrumentation and Methods for Astrophysics · Physics 2019-08-14 Matteo Giomi , Rolf Bühler , Carmelo Sgrò , Francesco Longo , William Atwood

We search for the presence of double gamma-ray line from unassociated Fermi-LAT sources including detailed Monte Carlo simulations to study its global statistical significance. Applying the Su & Finkbeiner selection criteria for high-energy…

High Energy Astrophysical Phenomena · Physics 2012-08-10 Andi Hektor , Martti Raidal , Elmo Tempel

Machine-learning (ML) algorithms will play a crucial role in studying the large datasets delivered by new facilities over the next decade and beyond. Here, we investigate the capabilities and limits of such methods in finding galaxies with…

Instrumentation and Methods for Astrophysics · Physics 2019-08-22 Andreas L. Faisst , Abhishek Prakash , Peter L. Capak , Bomee Lee

Various galaxy merger detection methods have been applied to diverse datasets. However, it is difficult to understand how they compare. We aim to benchmark the relative performance of machine learning (ML) merger detection methods. We…

We invoke a Gaussian mixture model (GMM) to jointly analyse two traditional emission-line classification schemes of galaxy ionization sources: the Baldwin-Phillips-Terlevich (BPT) and $\rm W_{H\alpha}$ vs. [NII]/H$\alpha$ (WHAN) diagrams,…

The identification of low-energy counterparts for gamma-ray sources is one of the biggest challenge in modern gamma-ray astronomy. Recently, we developed and successfully applied a new association method to recognize gamma-ray blazar…

High Energy Astrophysical Phenomena · Physics 2015-06-04 F. Massaro , A. Paggi , R. D'Abrusco , G. Tosti

We present a new method to interpret the $\gamma$-ray data of our inner Galaxy as measured by the Fermi Large Area Telescope (Fermi LAT). We train and test convolutional neural networks with simulated Fermi-LAT images based on models tuned…

High Energy Astrophysical Phenomena · Physics 2018-05-29 Sascha Caron , Germán A. Gómez-Vargas , Luc Hendriks , Roberto Ruiz de Austri

We present the results of an identification campaign of unassociated sources from the Fermi Large Area Telescope 3FHL catalog. Out of 200 unidentified sources, we selected 110 sources for which archival Swift-XRT observations were…

High Energy Astrophysical Phenomena · Physics 2019-01-25 Amanpreet Kaur , Marco Ajello , Stefano Marchesi , Nicola Omodei

We search for the long-term variability of the \gamma-ray sky in the energy range E > 1 GeV with 168 weeks of Fermi-LAT data. We perform a full sky blind search for regions with variable flux looking for deviations from uniformity. We bin…

High Energy Astrophysical Phenomena · Physics 2015-06-03 M. S. Pshirkov , G. I. Rubtsov

The global contribution of unresolved gamma-ray point sources to the extragalactic gamma-ray background has been recently measured down to gamma-ray fluxes lower than those reached with standard source detection techniques, and by employing…

High Energy Astrophysical Phenomena · Physics 2020-05-27 Silvia Manconi , Michael Korsmeier , Fiorenza Donato , Nicolao Fornengo , Marco Regis , Hannes Zechlin

We used random forest algorithms to classify all objects in a large portion of the sky, using optical light curves obtained, or built from images provided, by the Zwicky Transient Facility (ZTF). We compare different selection sets based on…

Astrophysics of Galaxies · Physics 2025-03-25 S. Bernal , P. Sánchez-Sáez , P. Arévalo , F. E. Bauer , P. Lira , B. Sotomayor

The field of gamma ray astronomy relies heavily on the statistical analysis of data. Because of the paucity of data, and the often large errors associated with detecting gamma rays, analysis and interpretation of the data require…

Astrophysics · Physics 2007-05-23 W. F. Tompkins

With a decade of gamma-ray data from the Fermi-LAT telescope, we can now hope to answer how well we know the local Universe at gamma-ray frequencies. On the other hand, with gamma-ray data alone it is not possible to directly access the…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-27 Simone Ammazzalorso , Nicolao Fornengo , Shunsaku Horiuchi , Marco Regis

The advent of new all-sky radio surveys such as the VLA Sky Survey (VLASS) and the Rapid ASKAP Continuum Survey (RACS), performed with the latest generation radio telescopes, is opening new possibilities on the classification and study of…

High Energy Astrophysical Phenomena · Physics 2022-04-06 G. Bruni , L. Bassani , M. Persic , Y. Rephaeli , A. Malizia , M. Molina , M. Fiocchi , R. Ricci , M. H. Wieringa , M. Giroletti , F. Panessa , A. Bazzano , P. Ubertini

We present the results of our follow-up observation program of gamma-ray sources detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. 26 blazars and 39 sources unidentified at other wavelengths were…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Mai Fujiwara , Yoshiki Matsuoka , Nobuyuki Ienaka

We present the first catalog of active galactic nuclei (AGN) detected by the LAT, corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 gamma-ray sources located at high…

High Energy Astrophysical Phenomena · Physics 2019-08-14 A. A. Abdo

We report on optical searches in the error circles of 93 ROSAT survey sources located at low galactic latitudes (|b| < 20 deg). These sources were extracted from the ROSAT Galactic Plane Survey using various selection criteria on hardness…

One of the main scientific objectives of the recent Fermi mission is investigating the origin of the unidentified gamma-ray sources (UGSs). Despite the large improvements of Fermi in the gamma-ray source localization with respect to the…

High Energy Astrophysical Phenomena · Physics 2013-03-15 F. Massaro , R. D'Abrusco , A. Paggi , N. Masetti , M. Giroletti , G. Tosti , Howard A. Smith

According to the second Fermi LAT Catalog (2FGL), about one third of the gamma-ray sources listed have no assigned counterparts at lower energies. Many statistical methods have been developed to find proper counterparts for these sources.…

High Energy Astrophysical Phenomena · Physics 2015-03-12 M. Nori , M. Giroletti , F. Massaro , R. D'Abrusco , A. Paggi , G. Tosti , S. Funk

Spatial extension is an important characteristic for correctly associating gamma-ray-emitting sources with their counterparts at other wavelengths and for obtaining an unbiased model of their spectra. We present a new method for quantifying…