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Browsing by Subject "Gamma rays: galaxies"

Browsing by Subject "Gamma rays: galaxies"

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  • Awakening of the high-redshift blazar CGRaBS J0809+5341 
    Paliya, Vaidehi S; Parker, M. L; Stalin, C. S; Fabian, A. C; Ramya, S; Covino, S; Tagliaferri, G; Sahayanathan, S; Ravikumar, C. D (IOP Publishing, 2015-04)
    CGRaBS J0809+5341, a high-redshift blazar at z = 2.144, underwent a giant optical outburst on 2014 April 19 when it brightened by ~5 mag and reached an unfiltered apparent magnitude of 15.7 mag. This implies an absolute ...
  • Broad-band study of OQ 334 during its flaring state 
    Prince, Raj; Khatoon, Rukaiya; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-04)
    The blazar OQ 334 displayed a γ-ray flare in 2018, after being in the long quiescent γ-ray state since 2008. Subsequent to the flare, the source was in a higher γ-ray flux state and again flared in 2020. We present here ...
  • Broadband observations of high redshift blazars 
    Paliya, Vaidehi S; Parker, M. L; Fabian, A. C; Stalin, C. S (IOP Publishing, 2016-07-01)
    We present a multi-wavelength study of four high redshift blazars, S5 0014+81 (z = 3.37), CGRaBS J0225+1846 (z = 2.69), BZQ J1430+4205 (z = 4.72), and 3FGL J1656.2−3303 (z = 2.40) using quasi-simultaneous data from the ...
  • Fermi monitoring of radio-loud narrow-line seyfert 1 galaxies 
    Paliya, Vaidehi S; Stalin, C. S; Ravikumar, C. D (IOP Publishing, 2015-02)
    We present detailed analysis of the γ-ray flux variability and spectral properties of the five radio-loud narrow line Seyfert 1 (RL-NLSy1) galaxies, detected by the Large Area Telescope on board the Fermi Gamma-Ray Space ...
  • The first GeV outburst of the radio-loud narrow-line Seyfert 1 galaxy PKS 1502+036 
    Paliya, Vaidehi S; Stalin, C. S (IOP Publishing, 2016-03)
    The γ-ray-loud narrow-line Seyfert 1 (γ-NLSy1) galaxy PKS 1502+036 (z = 0.409) exhibited its first γ-ray outburst on 2015 December 20. In the energy range of 0.1–300 GeV, the highest flux measured by the Fermi-Large Area ...
  • Gamma-Ray Blazars within the first 2 billion years 
    Ackermann, M; Ajello, M; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Becerra Gonzalez, J; Bellazzini, R; Bissaldi, E; Blandford, R. D; Bloom, E. D; Bonino, R; Bottacini, E; Bregeon, J; Bruel, P; Buehler, R; Buson, S; Cameron, R. A; Caragiulo, M; Caraveo, P. A; Cavazzut, E; Cecchi, C; Cheung, C. C; Chiang, J; Chiaro, G; Ciprini, S; Conrad, J; Costantin, D; Costanza, F; Cutini, S; D'Ammando, F; de Palma, F; Desiante, R; Digel, S. W; Di Lalla, N; Di Mauro, M; Di Venere, L; Domi­nguez, A; Drell, P. S; Favuzzi, C; Fegan, S. J; Ferrara, E. C; Finke, J; Focke, W. B; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Giordano, F; Giroletti, M; Green, D; Grenier, I. A; Guillemo, L; Guiriec, S; Hartmann, D. H; Hays, E; Marcotulli, L; Horan, D; Jogler, T; Johannesson, G; Johnson, A. S; Kuss, M; Mura, G. La; Larsson, S; Latronico, L; Li, J; Longo, F; Mazziotta, M. N; Loparco, F; Lovellette, M. N; Lubrano, P; Magill, J. D; Maldera, S; Manfreda, A; Michelson, P. F; Mirabal, N; Mitthumsiri, W; Mizuno, T; Monzani, M. E|; Morselli, A; Moskalenko, I. V; Negro, M; Rando, R; Nuss, E; Ohsugi, T; Ojha, R; Omodei, N; Orienti, M; Orlando, E; Ormes, J. F; Paliya, V. S; Paneque, D; Perkins, J. S; Rani, B; Persic, M; Pesce-Rollins, M; Piron, F; Porter, T. A; Principe, G; Raino, S; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Roman, R. W; Sgro, C; Simone, D; Siskind, E. J; Spada, F; Spandre, G; Spinelli, P; Stalin, C. S; 12 others (IOP Publishing, 2017-03-01)
    The detection of high-redshift ($z\,\gt 3$) blazars enables the study of the evolution of the most luminous relativistic jets over cosmic time. More importantly, high-redshift blazars tend to host massive black holes and ...
  • Gamma-Ray-emitting Narrow-line Seyfert 1 Galaxies in the Sloan Digital Sky Survey 
    Paliya, Vaidehi S; Ajello, M; Rakshit, S; Amit Kumar; Stalin, C. S; Kaur, A; Hartmann, D (IOP Publishing, 2018-01)
    The detection of signi fi cant γ -ray emission from radio-loud narrow-line Seyfert 1 ( NLSy1s ) galaxies enables us to study jets in environments different than those in blazars. However, due to the small number ...
  • A Hard gamma-ray flare from 3C 279 in 2013 December 
    Paliya, Vaidehi S; Diltz, Chris; Bottcher, Markus; Stalin, C. S; Buckley, David (IOP Publishing, 2016-01)
    The blazar 3C 279 exhibited twin γ -ray fl ares of similar intensity in 2013 December and 2014 April. In this work, we present a detailed multi-wavelength analysis of the 2013 December fl aring event. Multi-frequency ...
  • Long-term study of Mkn 421 with the HAGAR array of telescopes 
    Sinha, A; Shukla, A; Saha, L; Acharya, B. S; Anupama, G. C; Bhattacharjee, P; Britto, R. J; Chitnis, V. R; Prabhu, T. P; Singh, B. B; Vishwanath, P. R (EDP Sciences, 2016-07)
    Context. The HAGAR Telescope Array at Hanle, Ladakh has been regularly monitoring the nearby blazar Mkn 421 for the past seven years. Aims. Blazars show flux variability in all timescales across the electromagnetic ...
  • Multi-wavelength observations of 3C 279 during the extremely bright gamma-ray flare in 2014 March-April 
    Paliya, Vaidehi S; Sahayanathan, S; Stalin, C. S (IOP Publishing, 2015-04)
    The well-studied blazar 3C 279 underwent a giant γ-ray outburst in 2014 March–April. The measured γ-ray flux is the highest detected from 3C 279 by the Fermi Large Area Telescope. Hour scale γ-ray flux variability is ...
  • Multiwavelength study of the TeV blazar Mrk 421 during a giant flare 
    Shukla, A; Chitnis, V. R; Vishwanath, P. R; Acharya, B. S; Anupama, G. C; Bhattacharjee, P; Britto, R. J; Prabhu, T. P; Saha, L; Singh, B. B (EDP Sciences, 2012-05)
    Aims. The nearby (z = 0.031) TeV blazar Mrk 421 was reported to be in a high state of flux activity since November, 2009. We aim to investigate possible changes in the physical parameters of Mrk 421 during its high state ...
  • The Nature of γ -ray loud Narrow-line Seyfert I Galaxies PKS 1502+036 And PKS 2004-447 
    Paliya, Vaidehi S; Stalin, C. S; Shukla, A; Sahayanathan, S (IOP Publishing, 2013-05-01)
    Variable γ-ray emission has been discovered in five radio-loud narrow-line Seyfert 1 (NLSy1) galaxies by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. This has clearly demonstrated that these NLSy1 ...
  • Short-timescale γ -Ray Variability in CTA 102 
    Shukla, A; Mannheim, K; Patel, S. R; Roy, J; Chitnis, V. R; Dorner, D; Rao, A. R; Anupama, G. C; Wendel, C (IOP Publishing, 2018-02)
    The fl at-spectrum radio quasar CTA 102 experienced a prolonged state of enhanced activity across the entire observed electromagnetic spectrum during 2016 – 2017, most pronounced during a major outburst between ...
  • TXS 1206 + 549: a new γ -ray-detected narrow-line Seyfert 1 galaxy at redshift 1.34? 
    Rakshit, S; Schramm, Malte; Stalin, C. S; Tanaka, I; Paliya, Vaidehi S; Pal, Indrani; Kotilainen, Jari; Shin, Jaejin (Oxford University Press on behalf of the Royal Astronomical Society, 2021-06)
    Radio and γ-ray loud narrow-line Seyfert 1 galaxies (NLS1s) are unique objects to study the formation and evolution of relativistic jets, as they are believed to have high accretion rates and powered by low mass black holes ...

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