The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope

Ajello, M.; Angioni, R.; Axelsson, M.; Ballet, J.; Barbiellini, G.; Bastieri, D.; González, J. Becerra; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Bruel, P.; Buson, S.; Cafardo, Fabio; Cameron, R. A.; Cavazzuti, E.; Chen, Sina; Cheung, C. C.; Ciprini, S.; Costantin, D.; Cutini, S.; D’Ammando, F.; Luque, Pedro De la Torre; Menezes, Raniere de; Palma, F. de; Desai, Abhishek; Lalla, N. Di; Venere, L. Di; Domínguez, A.; Dirirsa, F.; Ferrara, E. C.; Finke, J.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Garrappa, S.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Green, D.; Grenier, I. A.; Guiriec, S.; Harita, S.; Hays, E.; Horan, D.; Itoh, R.; Jóhannesson, G.; Kovačević, M.; Krauß, F.; Kreter, M.; Kuss, M.; Larsson, Stefan; Leto, C.; Li, J.; Liodakis, Ioannis; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Maldera, S.; Manfreda, Alberto; Martí-Devesa, G.; Massaro, F.; Mazziotta, M. N.; Mereu, I.; Meyer, M.; Migliori, G.; Mirabal, N.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, Michela; Nemmen, Rodrigo; Nuss, E.; Ojha, L.; Ojha, R.; Omodei, N.; Orienti, M.; Orlando, Elena; Ormes, J. F.; Paliya, Vaidehi S.; Pei, Z. Y.; Peña-Herazo, H. A.; Peršić, M.; Pesce-Rollins, Melissa; Petrov, Leonid; Piron, F.; Poon, H.; Principe, G.; Rainò, S.; Rando, R.; Rani, Bindu; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Schinzel, F. K.; Serini, D.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tachibana, Y.; Thompson, D. J.; Torres, D. F.; Torresi, E.; Troja, E.; Valverde, J.; Zyl, P. van; Yassine, M.

doi:10.3847/1538-4357/ab791e

Cited by 277 publications

(228 citation statements)

References 183 publications

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“…Blazars, as the most extreme subclass of AGNs with a radio-loud behaviour and a relativistic jet pointing towards the observer (Urry & Padovani 1995), are characterised by having large amplitude and rapid variability, superluminal motion, high polarisation, core-dominated non-thermal continuum, and γ-ray emission, etc. (Wills et al 1992;Fan & Xie 1996;Bai et al 1998;Romero et al 2002;Fan 2005;Fan et al 2011Fan et al , 2013bFan et al , 2016Ghisellini et al 2010;Abdo et al 2009;Abdo et al 2010b,c;Urry 2011;Marscher et al 2011;Nolan et al 2012;Yang, Fan, & Yuan 2012;Yang et al 2019;Gupta et al 2012;Acero et al 2015;Xiao et al 2019;Ajello et al 2020;Pei et al 2019Pei et al , 2020a. All of these properties are due to the relativistic beaming effect.…”

Section: Introductionmentioning

confidence: 99%

“…After the launch of Fermi Large Area Telescope (hereafter, Fermi/LAT), many new high-energy γ-ray sources were detected, revolutionising, in particular, the knowledge of γ-ray blazars, providing us with the opportunity to study the γ-ray production mechanism. Based on the first 8 yr of data from the Fermi Gammaray Space Telescope mission, the latest catalogue, 4FGL, or the fourth Fermi Large Area Telescope catalogue of high-energy γ-ray sources, has been released, which includes 5 098 sources above the significance of 4σ , covering the 50 MeV−1 TeV range (Abdollahi et al 2020;Ajello et al 2020), about 2 000 more than the previous 3FGL catalogue (Acero et al 2015). AGNs are the vast majority of sources in 4FGL; among them 2 938 blazars, or 681 FSRQs, 1 102 BL Lacs and 1 152 blazar candidates of unknown class (BCUs, Abdollahi et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

Pei

Jiang

Yang

et al. 2020

Publ. Astron. Soc. Aust.

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Blazars are a subclass of active galactic nuclei with extreme observation properties, which is caused by the beaming effect, expressed by a Doppler factor ( $\delta$ ), in a relativistic jet. Doppler factor is an important parameter in the blazars paradigm to indicate all of the observation properties, and many methods were proposed to estimate its value. In this paper, we present a method following Mattox et al. to calculate the lower limit on $\gamma$ -ray Doppler factor ( $\delta_{\gamma}$ ) for 809 selected Fermi/LAT-detected $\gamma$ -ray blazars by adopting the available $\gamma$ -ray and X-ray data. Our sample included 342 flat-spectrum radio quasars (FSRQs) and 467 BL Lac objects (BL Lacs), out of which 507 sources are compiled with available radio core-dominance parameter (R) from our previous study. Our calculation shows that the average values of the lower limit on $\delta_{\gamma}$ for FSRQs and BL Lacs are $\left\langle\delta_{\gamma}|_{\textrm{FSRQ}}\right\rangle = 6.87 \pm 4.07$ and $\left\langle\delta_{\gamma}|_{\textrm{BL\ Lac}}\right\rangle=4.31 \pm 2.97$ , respectively. We compare and discuss our results with those from the literature. We found that the derived lower limit on $\delta_{\gamma}$ for some sources is higher than that from the radio estimation, which could be possibly explained by the jet bending within those blazars. Our results also suggest that the $\gamma$ -ray and radio regions perhaps share the same relativistic effects. The $\gamma$ -ray Doppler factor has been found to be correlated with both the $\gamma$ -ray luminosity and core-dominance parameter, implying that the jet is possibly continuous in the $\gamma$ -ray bands, and R is perhaps an indicator for a beaming effect.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

Pei

Jiang

Yang

et al. 2020

Publ. Astron. Soc. Aust.

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“…3. It has been readily detected and monitored by Fermi-LAT at γ-ray energies since 2008 (Abdollahi et al 2020;Ajello et al 2020). 4.…”

Section: Introductionmentioning

confidence: 99%

The Relativistic Jet Orientation and Host Galaxy of the Peculiar Blazar PKS 1413+135

Readhead

Ravi

Liodakis

et al. 2021

ApJ

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PKS 1413+135 is one of the most peculiar blazars known. Its strange properties led to the hypothesis almost four decades ago that it is gravitationally lensed by a mass concentration associated with an intervening galaxy. It exhibits symmetric achromatic variability, a rare form of variability that has been attributed to gravitational milli-lensing. It has been classified as a BL Lac object, and is one of the rare objects in this class with a visible counterjet. BL Lac objects have jet axes aligned close to the line of sight. It has also been classified as a compact symmetric object-objects that have jet axes not aligned close to the line of sight. Intensive efforts to understand this blazar have hitherto failed to resolve even the questions of the orientation of the relativistic jet and the host galaxy. Answering these two questions is important because they challenge our understanding of jets in active galactic nuclei and the classification schemes we use to describe them. We show that the jet axis is aligned close to the line of sight and PKS 1413+135 is almost certainly not located in the apparent host galaxy, but is a background object in the redshift range 0.247<z<0.5. The intervening spiral galaxy at z=0.247 provides a natural host for the putative lens responsible for symmetric achromatic variability and is shown to be a Seyfert 2 galaxy. We also show that, as for the radio emission, a "multizone" model is needed to account for the highenergy emission.

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“…Classification of Fermi-LAT sources with deep learning Silvia Manconi to previous works [7]. We also explored [10] the performance of the DNN, RNN with different data augmentation techniques and adding additional features, for example the synchrotron peak frequency as given in [14], finding slight improvements.…”

Section: Pos(icrc2021)664mentioning

confidence: 99%

Classification of Fermi-LAT sources with deep learning

Manconi¹,

Butter²,

Finke³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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Machine learning techniques are powerful tools for the classification of unidentified gamma-ray sources. We present a new approach based on dense and recurrent deep neural networks to classify unidentified or unassociated gamma-ray sources in the last release of the Fermi-LAT catalog (4FGL-DR2). Our method uses the actual measurements of the photon energy spectrum and time series as input for the classification, instead of specific, hand-crafted features. We focus on different classification tasks: the separation between extragalactic sources, i.e. Active Galactic Nuclei (AGN), and Galactic pulsars, the further classification of pulsars into young and millisecond pulsars and the sub-classification of AGN into different types. Since our method is very flexible, we generalise it to account for uncertainties in the predicted classes. Our list of high-confidence candidate sources labelled by the neural networks provides targets for further multiwavelength observations to identify their nature, as well as for population studies, and is available at https://github.com/manconi/agn-psr-nn-classification.

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The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope

Cited by 277 publications

References 183 publications

The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

The Relativistic Jet Orientation and Host Galaxy of the Peculiar Blazar PKS 1413+135

Classification of Fermi-LAT sources with deep learning

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