Results 41 to 50 of about 272 (130)

Quasi-periodicities of BL Lacertae objects [PDF]

Astronomy & Astrophysics, 2018
We review the reports of possible year-long quasi-periodicities of BL Lac objects in the γ-ray and optical bands, and present a homogeneous time analysis of the light curves of PKS2155−304, PG1553+113, and BL Lac. Based on results from a survey covering the entire Fermi γ-ray sky we have estimated the fraction of possible quasi-periodic BL Lac objects.
Sandrinelli A., Covino S., Treves A., Holgado A. M., Sesana A., Lindfors E., Ramazani V. F.   +6 more
openaire   +3 more sources

M87: A Misaligned BL Lacertae Object? [PDF]

The Astrophysical Journal, 1998
The nuclear region of M87 was observed with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) at six epochs, spanning 18 months, after the HST image quality was improved with the deployment of the corrective optics (COSTAR) in 1993 December.
Zlatan I. Tsvetanov, George F. Hartig, Holland C. Ford, Michael A. Dopita, Gerard A. Kriss, Yichuan C. Pei, Linda L. Dressel, Richard J. Harms   +7 more
openaire   +1 more source

Study of Variability in Long-term Multiwavelength Optical Lightcurves of Blazar AO 0235+164

The Astrophysical Journal Supplement Series, 2023
We present a long-term and intraday variability study of optical multiwaveband ( U BV RI ) data from the blazar AO 0235+164 collected by various telescopes for ∼44 yr (1975–2019).
Abhradeep Roy, Alok C. Gupta, Varsha R. Chitnis, Sergio A. Cellone, Claudia M. Raiteri, Gustavo E. Romero, Paul J. Wiita, Anshu Chatterjee, Jorge A. Combi, Mai Liao, Arkadipta Sarkar, Massimo Villata   +11 more
doaj   +1 more source

A Search for Low‐Luminosity BL Lacertae Objects

The Astrophysical Journal, 1999
Many properties of BL Lacs have become explicable in terms of the "relativistic beaming" hypothesis whereby BL Lacs are FR-1 radio galaxies viewed nearly along the jet axis. However, a possible problem with this model is that a transition population between beamed BL Lacs and unbeamed FR-1s has not been detected.
Rector, Travis A., Stocke, John T., Perlman, Eric S.   +2 more
openaire   +2 more sources

Characterizing Multiband Optical Emission and Variability of 1ES 1215+303 on Diverse Timescales

The Astrophysical Journal
This study presents analyses of the optical variability of the 1ES 1215+303 on diverse timescales using multiband observations, including observations in the optical BVRI bands carried out with the 0.6 and 1.0 m telescopes located at the Tübitak National
A. Ozdonmez, H. Er, M. Tekkesinoglu, E. Ege, M. E. Kenger, I. C. Ozkesen, A. Polatoğlu   +6 more
doaj   +1 more source

UBVRI observations of BL Lacertae objects

The Astrophysical Journal Supplement Series, 1985
A total of 85 UBVRI observations of BL Lac objects is presented. For most of them, an average continuum can be traced by means of well-defined color indices. These continua are always well reproduced by power laws, strongly supporting the hypothesis of a synchrotron origin of the radiation output, as well as the conclusion that there is no dust in such
M. Moles, J. M. Garcia-Pelayo, J. Masegosa, A. Aparicio   +3 more
openaire   +1 more source

Infrared Variation of Radio‐selected BL Lacertae Objects [PDF]

The Astrophysical Journal Supplement Series, 1999
27 page, 12 figures; 4 tables, ApJS, 121, 131 (1999)
Fan, J. H., Lin, R. G.
openaire   +2 more sources

Very-high-energy gamma-ray intranight variability from BL Lacertae during the extreme flaring state of 2022

Astronomy & Astrophysics
Context. BL Lacertae (BL Lac), the archetypal blazar of its subclass and one of the most studied blazars of recent decades, has undergone a series of major multi-wavelength outbursts since 2020, resulting in its highest recorded γ-ray flare to date ...
Abe K., Abe S., Abhishek A., Acero F., Aguasca-Cabot A., Agudo I., Alispach C., Ambrosino D., Ambrosino F., Antonelli L. A., Aramo C., Arbet-Engels A., Arcaro C., Arnesen T. T. H., Aubert P., Baktash A., Balbo M., Bamba A., Baquero Larriva A., Barres de Almeida U., Barrio J. A., Barrios Jiménez L., Batkovic I., Baxter J., Becerra González J., Bernete J., Berti A., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Briscioli A., Brunelli G., Buces J., Bulgarelli A., Burelli I., Burmistrov L., Cardillo M., Caroff S., Carosi A., Carraro R., Cassol F., Cerasole D., Cerviño Cortínez A., Chai Y., Chon G., Chytka L., Cicciari G. M., Contreras J. L., Cortina J., Costantini H., Croisonnier M., Dalchenko M., D’Amico G., Da Vela P., Dazzi F., De Angelis A., de Bony de Lavergne M., Del Burgo R., Delgado C., Delgado Mengual J., della Volpe D., De Lotto B., Del Peral L., de Menezes R., De Palma G., de Souza V., Díaz C., Di Bella L., Di Piano A., Di Pierro F., Di Tria R., Di Venere L., Dominis Prester D., Donini A., Dorner D., Eisenberger L., Elsässer D., Emery G., Feligioni L., Ferrarotto F., Fiasson A., Foffano L., Fukazawa Y., Gallozzi S., Garcia López R., Garcia Soto S., Gasbarra C., Gasparrini D., Giesbrecht Paiva J., Giglietto N., Giordano F., Godinovic N., Gradetzke T., Grau R., Green J., Grolleron G., Gunji S., Günther P., Hackfeld J., Hadasch D., Hashizume M., Hassan T., Hayashi K., Heckmann L., Heller M., Herrera Llorente J., Hiroshima N., Hoffmann D., Horns D., Houles J., Hrupec D., Imazawa R., Inada T., Inoue S., Ioka K., Iori M., Itokawa T., Iuliano A., Jahanvi J., Jimenez Martinez I., Jimenez Quiles J., Jorge Rodrigo I., Jurysek J., Kagaya M., Karas V., Katagiri H., Kerszberg D., Kiyomoto T., Kobayashi Y., Kohri K., Kornecki P., Kubo H., Kushida J., Lacave B., Lainez M., Lamastra A., Lemoigne L., Linhoff M., Lombardi S., Longo F., López-Coto R., López-Oramas A., Loporchio S., Lozano Bahilo J., Lucarelli F., Luciani H., Luque-Escamilla P. L., Makariev M., Mallamaci M., Mandat D., Mannheim K., Marini F., Mariotti M., Marquez P., Marsella G., Martí J., Martinez O., Martínez G., Martínez M., Massa M., Mazin D., Méndez-Gallego J., Menon S., Mestre Guillen E., Miceli D., Miener T., Miranda J. M., Molero Gonzalez M., Molina E., Montaruli T., Moralejo A., Morselli A., Moya V., Müller A. L., Muraishi H., Nagataki S., Nakamori T., Neronov A., Nieto Castaño D., Nievas Rosillo M., Nikolic L., Noda K., Novotny V., Nozaki S., Ohishi M., Ohtani Y., Okumura A., Orito R., Orsini L., Otero-Santos J., Ottanelli P., Palatiello M., Panebianco G., Paneque D., Paoletti R., Paredes J. M., Pech M., Pecimotika M., Peresano M., Perrotta F., Pfeifle F., Pihet M., Pirola G., Plard C., Podobnik F., Polo M., Pozo-Gonzaléz C., Prandini E., Rainò S., Rando R., Rhode W., Ribó M., Rodriguez Fernandez G., Rodríguez Frías M. D., Roy A., Ruina A., Ruiz-Velasco E., Saito T., Sakurai S., Sanchez D. A., Sano H., Santos Moura E., Šarić T., Sato Y., Saturni F. G., Savchenko V., Schiavone F., Schussler F., Schweizer T., Seglar Arroyo M., Silvestri G., Simongini A., Sitarek J., Sliusar V., Sofia I., Strišković J., Strzys M., Suda Y., Sunny A., Tajima H., Takahashi M., Takeishi R., Tanaka S. J., Tateishi D., Tavernier T., Temnikov P., Terada Y., Terauchi K., Terzic T., Teshima M., Tluczykont M., Tomura T., Torres D. F., Tramonti F., Travnicek P., Tripodo G., Tutone A., Vacula M., Vázquez Acosta M., Verna G., Viale I., Viana A., Vigliano A., Vigorito C. F., Visentin E., Vitale V., Voutsinas G., Vovk I., Vuillaume T., Walter R., Yamamoto T., Yamazaki R., Yao Y., Yoshida T., Yoshikoshi T., Zhang W., Zywucka N., Aceituno F., Acosta-Pulido J. A., Casanova V., Escudero Pedrosa J., Fallah Ramazani V., Jormanainen J., Jorstad S., Keating G., Kouch P. M., Gurwell M., Lähteenmäki A., Lindfors E., Marscher A., Morcuende D., Myserlis I., Nilsson K., Ortega Hunter C. A., Rao R., Sota A., Tornikoski M., Zhang H.   +298 more
doaj   +1 more source

Classification of Blazar Candidates of Unknown Type in Fermi 4LAC by Unanimous Voting from Multiple Machine-learning Algorithms

The Astrophysical Journal, 2023
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 Lac objects), 1208 are blazars of unknown (BCUs) type ...
A. Agarwal
doaj   +1 more source

The Energy Budget in the Jet of High-frequency Peaked BL Lacertae Objects

The Astrophysical Journal
Energy equipartition and the energy budget in the jet are important issues for the radiation mechanism of blazars. Early work predominantly concentrated on flat-spectrum radio quasars and a limited number of BL Lacertae (BL Lac) objects.
X. Z. Zhao, H. Y. Yang, Y. G. Zheng, S. J. Kang   +3 more
doaj   +1 more source