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Article ; Online: The optical-gamma correlation in BL Lacertae

Raiteri Claudia M. / Villata Massimo / D’Ammando Filippo / Larionov Valeri M. / Gurwell Mark A. / Mirzaqulov Davron O. / Smith Paul S. / Carnerero Maria Isabel

EPJ Web of Conferences, Vol 61, p

2013 Volume 04014

Abstract: We present multifrequency light curves of BL Lacertae from February 2008 to October 2012. Lowenergy data (optical and millimetre) were acquired in the framework of a GASP-WEBT project. High-energy data (ultraviolet, X-ray, and γ-ray) come from ... ...

Abstract	We present multifrequency light curves of BL Lacertae from February 2008 to October 2012. Lowenergy data (optical and millimetre) were acquired in the framework of a GASP-WEBT project. High-energy data (ultraviolet, X-ray, and γ-ray) come from observations of the Swift, RXTE, and Fermi satellites. After a period of moderate activity, in May 2011 the source suddenly started to flare at γ and optical-UV frequencies. Activity at millimetre wavelengths and X rays began 3-4 months later. This behaviour offered a good opportunity to study the correlation among flux variability in different bands, in particular between the best-sampled optical and γ-ray light curves. However, even in this fortuitous case, we can only define a general correlation with likely no time lag, but with a lag uncertainty of ±1 day. Indeed, the data reveal a complex relationship between the γ and optical fluxes, which cannot be unveiled because of the small gaps in the sampling of this extremely variable source.
Keywords	Physics ; QC1-999 ; Science ; Q ; DOAJ:Physics (General) ; DOAJ:Physics and Astronomy
Subject code	535
Language	English
Publishing date	2013-12-01T00:00:00Z
Publisher	EDP Sciences
Document type	Article ; Online
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Article ; Online: The Gamma-ray Activity of the high-z Quasar 0836+71

Jorstad Svetlana / Marscher Alan / Larionov Valeri / Gómez José L. / Agudo Iván / Angelakis Emmanouil / Casadio Carolina / Gurwell Mark / Hovatta Talvikki / Joshi Manasvita / Fuhrmann Lars / Karamanavis Vassilis / Lähteenmäki Anne / Molina Sol / Morozova Daria / Myserlis Ioannis / Troitsky Ivan / Ungerechts Hans / Anton Zensus J.

EPJ Web of Conferences, Vol 61, p

2013 Volume 04003

Abstract: The Fermi LAT detected an increase in γ-ray activity of the quasar 0836+710 (z=2.17) in Spring 2011 that culminated in a sharp γ-ray flare at the end of 2011 when the source reached a flux of 2.9×10−6 phot s−1cm−2 at 0.1-200 GeV. We monitor the quasar at ...

Abstract	The Fermi LAT detected an increase in γ-ray activity of the quasar 0836+710 (z=2.17) in Spring 2011 that culminated in a sharp γ-ray flare at the end of 2011 when the source reached a flux of 2.9×10−6 phot s−1cm−2 at 0.1-200 GeV. We monitor the quasar at optical wavelengths in photometric and polarimetric modes, at millimeter and centimeter wavelengths, and with the VLBA at 43 GHz. The optical brightness of the quasar increased by ~0.5 mag in R band and the degree of polarization oscillated between ~1% and ~6% during the highest γ-ray state, while the position angle of polarization rotated by ~300°. We have identified in the VLBA images a strong, highly polarized component that moves with an apparent speed of ~20 c. The component emerged from the core in the beginning of the γ-ray event and reached a flux maximum at the peak of the γ-ray outburst. We present the results of a correlative analysis of variations at different wavelengths along with the kinematic parameters of the parsec scale jet. We discuss the location of the high γ-ray emission in the relativistic jet, as well as the emission mechanisms responsible for γ-ray production.
Keywords	Physics ; QC1-999 ; Science ; Q ; DOAJ:Physics (General) ; DOAJ:Physics and Astronomy
Subject code	520
Language	English
Publishing date	2013-12-01T00:00:00Z
Publisher	EDP Sciences
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Jet-launching structure resolved near the supermassive black hole in M87.

Doeleman, Sheperd S / Fish, Vincent L / Schenck, David E / Beaudoin, Christopher / Blundell, Ray / Bower, Geoffrey C / Broderick, Avery E / Chamberlin, Richard / Freund, Robert / Friberg, Per / Gurwell, Mark A / Ho, Paul T P / Honma, Mareki / Inoue, Makoto / Krichbaum, Thomas P / Lamb, James / Loeb, Abraham / Lonsdale, Colin / Marrone, Daniel P /

Moran, James M / Oyama, Tomoaki / Plambeck, Richard / Primiani, Rurik A / Rogers, Alan E E / Smythe, Daniel L / SooHoo, Jason / Strittmatter, Peter / Tilanus, Remo P J / Titus, Michael / Weintroub, Jonathan / Wright, Melvyn / Young, Ken H / Ziurys, Lucy M

Science (New York, N.Y.)

2012 Volume 338, Issue 6105, Page(s) 355–358

Abstract: Approximately 10% of active galactic nuclei exhibit relativistic jets, which are powered by the accretion of matter onto supermassive black holes. Although the measured width profiles of such jets on large scales agree with theories of magnetic ... ...

Abstract	Approximately 10% of active galactic nuclei exhibit relativistic jets, which are powered by the accretion of matter onto supermassive black holes. Although the measured width profiles of such jets on large scales agree with theories of magnetic collimation, the predicted structure on accretion disk scales at the jet launch point has not been detected. We report radio interferometry observations, at a wavelength of 1.3 millimeters, of the elliptical galaxy M87 that spatially resolve the base of the jet in this source. The derived size of 5.5 ± 0.4 Schwarzschild radii is significantly smaller than the innermost edge of a retrograde accretion disk, suggesting that the M87 jet is powered by an accretion disk in a prograde orbit around a spinning black hole.
Language	English
Publishing date	2012-10-19
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	128410-1
ISSN	1095-9203 ; 0036-8075
ISSN (online)	1095-9203
ISSN	0036-8075
DOI	10.1126/science.1224768
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Article ; Online: Resolved magnetic-field structure and variability near the event horizon of Sagittarius A.

Johnson, Michael D / Fish, Vincent L / Doeleman, Sheperd S / Marrone, Daniel P / Plambeck, Richard L / Wardle, John F C / Akiyama, Kazunori / Asada, Keiichi / Beaudoin, Christopher / Blackburn, Lindy / Blundell, Ray / Bower, Geoffrey C / Brinkerink, Christiaan / Broderick, Avery E / Cappallo, Roger / Chael, Andrew A / Crew, Geoffrey B / Dexter, Jason / Dexter, Matt /

Freund, Robert / Friberg, Per / Gold, Roman / Gurwell, Mark A / Ho, Paul T P / Honma, Mareki / Inoue, Makoto / Kosowsky, Michael / Krichbaum, Thomas P / Lamb, James / Loeb, Abraham / Lu, Ru-Sen / MacMahon, David / McKinney, Jonathan C / Moran, James M / Narayan, Ramesh / Primiani, Rurik A / Psaltis, Dimitrios / Rogers, Alan E E / Rosenfeld, Katherine / SooHoo, Jason / Tilanus, Remo P J / Titus, Michael / Vertatschitsch, Laura / Weintroub, Jonathan / Wright, Melvyn / Young, Ken H / Zensus, J Anton / Ziurys, Lucy M

Science (New York, N.Y.)

2015 Volume 350, Issue 6265, Page(s) 1242–1245

Abstract: Near a black hole, differential rotation of a magnetized accretion disk is thought to produce an instability that amplifies weak magnetic fields, driving accretion and outflow. These magnetic fields would naturally give rise to the observed synchrotron ... ...

Abstract	Near a black hole, differential rotation of a magnetized accretion disk is thought to produce an instability that amplifies weak magnetic fields, driving accretion and outflow. These magnetic fields would naturally give rise to the observed synchrotron emission in galaxy cores and to the formation of relativistic jets, but no observations to date have been able to resolve the expected horizon-scale magnetic-field structure. We report interferometric observations at 1.3-millimeter wavelength that spatially resolve the linearly polarized emission from the Galactic Center supermassive black hole, Sagittarius A*. We have found evidence for partially ordered magnetic fields near the event horizon, on scales of ~6 Schwarzschild radii, and we have detected and localized the intrahour variability associated with these fields.
Language	English
Publishing date	2015-12-04
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	128410-1
ISSN	1095-9203 ; 0036-8075
ISSN (online)	1095-9203
ISSN	0036-8075
DOI	10.1126/science.aac7087
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Article ; Online: Bright radio emission from an ultraluminous stellar-mass microquasar in M 31.

Middleton, Matthew J / Miller-Jones, James C A / Markoff, Sera / Fender, Rob / Henze, Martin / Hurley-Walker, Natasha / Scaife, Anna M M / Roberts, Timothy P / Walton, Dominic / Carpenter, John / Macquart, Jean-Pierre / Bower, Geoffrey C / Gurwell, Mark / Pietsch, Wolfgang / Haberl, Frank / Harris, Jonathan / Daniel, Michael / Miah, Junayd / Done, Chris /

Morgan, John S / Dickinson, Hugh / Charles, Phil / Burwitz, Vadim / Della Valle, Massimo / Freyberg, Michael / Greiner, Jochen / Hernanz, Margarita / Hartmann, Dieter H / Hatzidimitriou, Despina / Riffeser, Arno / Sala, Gloria / Seitz, Stella / Reig, Pablo / Rau, Arne / Orio, Marina / Titterington, David / Grainge, Keith

Nature

2013 Volume 493, Issue 7431, Page(s) 187–190

Abstract: A subset of ultraluminous X-ray sources (those with luminosities of less than 10(40) erg s(-1); ref. 1) are thought to be powered by the accretion of gas onto black holes with masses of ∼5-20M cicled dot, probably by means of an accretion disk. The X-ray ...

Abstract	A subset of ultraluminous X-ray sources (those with luminosities of less than 10(40) erg s(-1); ref. 1) are thought to be powered by the accretion of gas onto black holes with masses of ∼5-20M cicled dot, probably by means of an accretion disk. The X-ray and radio emission are coupled in such Galactic sources; the radio emission originates in a relativistic jet thought to be launched from the innermost regions near the black hole, with the most powerful emission occurring when the rate of infalling matter approaches a theoretical maximum (the Eddington limit). Only four such maximal sources are known in the Milky Way, and the absorption of soft X-rays in the interstellar medium hinders the determination of the causal sequence of events that leads to the ejection of the jet. Here we report radio and X-ray observations of a bright new X-ray source in the nearby galaxy M 31, whose peak luminosity exceeded 10(39) erg s(-1). The radio luminosity is extremely high and shows variability on a timescale of tens of minutes, arguing that the source is highly compact and powered by accretion close to the Eddington limit onto a black hole of stellar mass. Continued radio and X-ray monitoring of such sources should reveal the causal relationship between the accretion flow and the powerful jet emission.
Language	English
Publishing date	2013-01-10
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	120714-3
ISSN	1476-4687 ; 0028-0836
ISSN (online)	1476-4687
ISSN	0028-0836
DOI	10.1038/nature11697
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole.

Psaltis, Dimitrios / Medeiros, Lia / Christian, Pierre / Özel, Feryal / Akiyama, Kazunori / Alberdi, Antxon / Alef, Walter / Asada, Keiichi / Azulay, Rebecca / Ball, David / Baloković, Mislav / Barrett, John / Bintley, Dan / Blackburn, Lindy / Boland, Wilfred / Bower, Geoffrey C / Bremer, Michael / Brinkerink, Christiaan D / Brissenden, Roger /

Britzen, Silke / Broguiere, Dominique / Bronzwaer, Thomas / Byun, Do-Young / Carlstrom, John E / Chael, Andrew / Chan, Chi-Kwan / Chatterjee, Shami / Chatterjee, Koushik / Chen, Ming-Tang / Chen, Yongjun / Cho, Ilje / Conway, John E / Cordes, James M / Crew, Geoffrey B / Cui, Yuzhu / Davelaar, Jordy / De Laurentis, Mariafelicia / Deane, Roger / Dempsey, Jessica / Desvignes, Gregory / Dexter, Jason / Eatough, Ralph P / Falcke, Heino / Fish, Vincent L / Fomalont, Ed / Fraga-Encinas, Raquel / Friberg, Per / Fromm, Christian M / Gammie, Charles F / García, Roberto / Gentaz, Olivier / Goddi, Ciriaco / Gómez, José L / Gu, Minfeng / Gurwell, Mark / Hada, Kazuhiro / Hesper, Ronald / Ho, Luis C / Ho, Paul / Honma, Mareki / Huang, Chih-Wei L / Huang, Lei / Hughes, David H / Inoue, Makoto / Issaoun, Sara / James, David J / Jannuzi, Buell T / Janssen, Michael / Jiang, Wu / Jimenez-Rosales, Alejandra / Johnson, Michael D / Jorstad, Svetlana / Jung, Taehyun / Karami, Mansour / Karuppusamy, Ramesh / Kawashima, Tomohisa / Keating, Garrett K / Kettenis, Mark / Kim, Jae-Young / Kim, Junhan / Kim, Jongsoo / Kino, Motoki / Koay, Jun Yi / Koch, Patrick M / Koyama, Shoko / Kramer, Michael / Kramer, Carsten / Krichbaum, Thomas P / Kuo, Cheng-Yu / Lauer, Tod R / Lee, Sang-Sung / Li, Yan-Rong / Li, Zhiyuan / Lindqvist, Michael / Lico, Rocco / Liu, Jun / Liu, Kuo / Liuzzo, Elisabetta / Lo, Wen-Ping / Lobanov, Andrei P / Lonsdale, Colin / Lu, Ru-Sen / Mao, Jirong / Markoff, Sera / Marrone, Daniel P / Marscher, Alan P / Martí-Vidal, Iván / Matsushita, Satoki / Mizuno, Yosuke / Mizuno, Izumi / Moran, James M / Moriyama, Kotaro / Moscibrodzka, Monika / Müller, Cornelia / Musoke, Gibwa / Mus Mejías, Alejandro / Nagai, Hiroshi / Nagar, Neil M / Narayan, Ramesh / Narayanan, Gopal / Natarajan, Iniyan / Neri, Roberto / Noutsos, Aristeidis / Okino, Hiroki / Olivares, Héctor / Oyama, Tomoaki / Palumbo, Daniel C M / Park, Jongho / Patel, Nimesh / Pen, Ue-Li / Piétu, Vincent / Plambeck, Richard / PopStefanija, Aleksandar / Prather, Ben / Preciado-López, Jorge A / Ramakrishnan, Venkatessh / Rao, Ramprasad / Rawlings, Mark G / Raymond, Alexander W / Ripperda, Bart / Roelofs, Freek / Rogers, Alan / Ros, Eduardo / Rose, Mel / Roshanineshat, Arash / Rottmann, Helge / Roy, Alan L / Ruszczyk, Chet / Ryan, Benjamin R / Rygl, Kazi L J / Sánchez, Salvador / Sánchez-Arguelles, David / Sasada, Mahito / Savolainen, Tuomas / Schloerb, F Peter / Schuster, Karl-Friedrich / Shao, Lijing / Shen, Zhiqiang / Small, Des / Sohn, Bong Won / SooHoo, Jason / Tazaki, Fumie / Tilanus, Remo P J / Titus, Michael / Torne, Pablo / Trent, Tyler / Traianou, Efthalia / Trippe, Sascha / van Bemmel, Ilse / van Langevelde, Huib Jan / van Rossum, Daniel R / Wagner, Jan / Wardle, John / Ward-Thompson, Derek / Weintroub, Jonathan / Wex, Norbert / Wharton, Robert / Wielgus, Maciek / Wong, George N / Wu, Qingwen / Yoon, Doosoo / Young, André / Young, Ken / Younsi, Ziri / Yuan, Feng / Yuan, Ye-Fei / Zhao, Shan-Shan

Physical review letters

2020 Volume 125, Issue 14, Page(s) 141104

Abstract: The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field ...

Abstract	The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak-field tests can lead to large deviations in the predicted black-hole shadows that are inconsistent with even the current EHT measurements. We use numerical calculations of regular, parametric, non-Kerr metrics to identify the common characteristic among these different parametrizations that control the predicted shadow size. We show that the shadow-size measurements place significant constraints on deviation parameters that control the second post-Newtonian and higher orders of each metric and are, therefore, inaccessible to weak-field tests. The new constraints are complementary to those imposed by observations of gravitational waves from stellar-mass sources.
Language	English
Publishing date	2020-10-08
Publishing country	United States
Document type	Journal Article
ZDB-ID	208853-8
ISSN	1079-7114 ; 0031-9007
ISSN (online)	1079-7114
ISSN	0031-9007
DOI	10.1103/PhysRevLett.125.141104
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Article ; Online: The optical-gamma correlation in BL Lacertae

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Article ; Online: The Gamma-ray Activity of the high-z Quasar 0836+71

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Article ; Online: Jet-launching structure resolved near the supermassive black hole in M87.

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Article ; Online: Resolved magnetic-field structure and variability near the event horizon of Sagittarius A.

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Article ; Online: Bright radio emission from an ultraluminous stellar-mass microquasar in M 31.

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Article ; Online: Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole.

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