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The Fermi fourth catalog of active galactic nuclei (AGNs) data release 3 (4LAC-DR3) contains 3407 AGNs, out of which 755 are flat spectrum radio quasars (FSRQs), 1379 are BL Lacertae objects (BL Lacs), 1208 are blazars of unknown (BCUs)…

高能天体物理现象 · 物理学 2023-04-12 Aditi Agarwal

In the third catalog of active galactic nuclei detected by the Fermi-LAT (3LAC) Clean Sample, there are 402 blazars candidates of uncertain type (BCU). Due to the limitations of astronomical observation or intrinsic properties, it is…

高能天体物理现象 · 物理学 2019-03-06 Shi-Ju Kang , Junhui Fan , Weiming Mao , Qingwen Wu , Jianchao Feng , Yue Yin

The Fermi Large Area Telescope (LAT) has detected more than 5000 gamma-ray sources in its first 8 years of operation. More than 3000 of them are blazars. About 60 per cent of the Fermi-LAT blazars are classified as BL Lacertae objects (BL…

高能天体物理现象 · 物理学 2020-06-22 Miloš Kovačević , Graziano Chiaro , Sara Cutini , Gino Tosti

The Fermi Large Area Telescope (Fermi-LAT) has detected more than 7,000 gamma-ray sources, a significant fraction of which are identified as blazars, while a comparable number remain classified as blazars of uncertain type (BCUs) or are…

高能天体物理现象 · 物理学 2026-02-03 Saqlain Afroz , Titir Mukherjee , Raj Prince

The recently published fourth Fermi Large Area Telescope source catalog (4FGL) reports 5065 gamma-ray sources in terms of direct observational gamma-ray properties. Among the sources, the largest population is the Active Galactic Nuclei…

高能天体物理现象 · 物理学 2020-01-08 Shi-Ju Kang , Enze Li , Wujing Ou , Kerui Zhu , Jun-Hui Fan , Qingwen Wu , Yue Yin

In this work, Machine Learning (ML) methods are used to efficiently identify the unassociated sources and the Blazar Candidate of Uncertain types (BCUs) in the Fermi-LAT Third Source Catalog (3FGL). The aims are twofold: 1) to distinguish…

高能天体物理现象 · 物理学 2020-05-08 Hubing Xiao , Haitao Cao , Junhui Fan , Denise Costantin , Gaoyong Luo , Zhiyuan Pei

The deepest all-sky survey available in the $\gamma$-ray band - the last release of the Fermi-LAT catalogue (4FGL-DR3) based on the data accumulated in 12 years, contains more than 6600 sources. The largest population among the sources is…

高能天体物理现象 · 物理学 2022-12-28 N. Sahakyan , V. Vardanyan , M. Khachatryan

The Fermi Large Area Telescope (LAT) is currently the most important facility for investigating the GeV $\gamma$-ray sky. With Fermi LAT more than three thousand $\gamma$-ray sources have been discovered so far. 1144 ($\sim40\%$) of the…

高能天体物理现象 · 物理学 2016-09-07 G. Chiaro , D. Salvetti , G. La Mura , M. Giroletti , D. J. Thompson , D. Bastieri

Machine learning has emerged as a powerful tool in the field of gamma-ray astrophysics. The algorithms can distinguish between different source types, such as blazars and pulsars, and help uncover new insights into the high-energy universe.…

高能天体物理现象 · 物理学 2024-01-05 Gopal Bhatta , Sarvesh Gharat , Abhimanyu Borthakur , Aman Kumar

In the third catalog of active galactic nuclei detected by the $Fermi$ Large Area Telescope Clean (3LAC) sample, there are 402 blazars candidates of uncertain type (BCU). The proposed analysis will help to evaluate the potential optical…

高能天体物理现象 · 物理学 2020-03-16 Shi-Ju Kang , Kerui Zhu , Jianchao Feng , Qingwen Wu , Bin-Bin Zhang , Yue Yin , Fei-Fei Wang , Yu Liu , Tian-Yuan Zheng

Machine learning is an automatic technique that is revolutionizing scientific research, with innovative applications and wide use in astrophysics. The aim of this study was to developed an optimized version of an Artificial Neural Network…

高能天体物理现象 · 物理学 2020-06-26 Miloš Kovačević , Graziano Chiaro , Sara Cutini , Gino Tosti

Machine learning (ML) and deep learning (DL) techniques are increasingly used across astrophysics, enabled by the growing availability of data and improved acquisition methods. These approaches now support tasks from redshift estimation to…

高能天体物理现象 · 物理学 2025-07-09 E. Oukacha , Y. Becherini

Machine learning based approaches are emerging as very powerful tools for many applications including source classification in astrophysics research due to the availability of huge high quality data from different surveys in observational…

高能天体物理现象 · 物理学 2023-07-05 A. Tolamatti , K. K. Singh , K. K. Yadav

Context. Blazars are a distinct subclass of active galactic nuclei (AGN), known for their fast variability, high polarization, and intense emission across the electromagnetic spectrum, from radio waves to gamma rays. Gamma-ray blazar…

高能天体物理现象 · 物理学 2025-01-08 N. Álvarez Crespo , A. Domínguez , V. S. Paliya , M. Chamorro Cazorla , P. Sánchez Blázquez , A. Gil de Paz

We aim to test if a blazar candidate of uncertain-type (BCU) in the third Fermi active galactic nuclei catalog (3LAC) can be potentially classified as a BL Lac object or a flat spectrum radio quasar (FSRQ) by performing a statistical…

高能天体物理现象 · 物理学 2017-03-29 Ting-Feng Yi , Jin Zhang , Rui-Jing Lu , Rui Huang , En-Wei Liang

An equivalent width (EW) based classification may cause the erroneous judgement to the flat spectrum radio quasars (FSRQs) and BL Lacerate objects (BL Lac) due to the diluting the line features by dramatic variations in the jet continuum…

高能天体物理现象 · 物理学 2023-08-14 Shi-Ju Kang , Yong-Gang Zheng , Qingwen Wu

We utilize machine learning methods to distinguish BL Lacertae objects (BL Lac) from Flat Spectrum Radio Quasars (FSRQ) within a sample of likely X-ray blazar counterparts to Fermi 3FGL unassociated gamma-ray sources. From our previous…

高能天体物理现象 · 物理学 2021-03-03 Amanpreet Kaur , Abraham D. Falcone , Michael C. Stroh

In this work, the support vector machine (SVM) method is adopted to separate BL Lacertae objects (BL Lacs) and flat spectrum radio quasars (FSRQs) in the plots of photon spectrum index against the photon flux, $\alpha_{\rm ph} \sim {\rm…

Among the ~2157 unassociated sources in the third data release (DR3) of the fourth Fermi catalog, ~1200 were observed with the Neil Gehrels Swift Observatory pointed instruments. These observations yielded 238 high S/N X-ray sources within…

高能天体物理现象 · 物理学 2023-02-15 Amanpreet Kaur , Stephen Kerby , Abraham D. Falcone

The extragalactic $\gamma$-rays sky observed by Fermi-Large Area Telescope (LAT) is dominated by blazars. In the fourth release of the Fermi-LAT Point Source Catalog (4FGL), are sources showing a multifrequency behavior similar to that of…

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