Now showing items 1-17 of 17

    • Calorimetric neutrino expectations from bright blazar flares 

      Kreter, Michael; Kadler, Matthias; Krauß, Felicia; Buson, Sara; Ojha, Roopesh; Mannheim, Karl; Wilms, Jörn; Böttcher, Markus; Fermi/LAT Collaboration (Proceedings of Science, 2019-07-24)
      Blazar jets are extreme environments, in which relativistic proton interactions with an ultraviolet photon field could give rise to photopion production. High-confidence associations of individual high-energy neutrinos ...
    • A Hard X-ray Survey of Radio-Selected Blazars 

      Langejahn, Marcus; Kadler, Matthias; Wilms, Jorn; Bock, M.; Baumgartner, W.H.; Gehrels, N.; Markwardt, C.B.; Tueller, J.
      The MOJAVE program has been monitoring a statistically complete sample of 135 radio-loud active galactic nuclei (AGN) of the northern hemisphere using the Very Long Baseline Array (VLBA). This sample, dominated by low-peaked ...
    • Kiloparsec-scale Jets: Physics, Emission Mechanisms, and Challenges 

      Perlman, Eric S.; Meyer, Eileen; Eilek, Jean; Tchekhovskoy, Sasha; Nyland, Kristina; Agudo, Ivan; Baum, Stefi; Hardcastle, Martin; Kadler, Matthias; Labiano, Alvaro; Marshall, Herman; O’Dea, Christopher; Worrall, Diana (2019-03-08)
      Jets are a ubiquitous part of the accretion process, created in AGN, by a coupling between the magnetic field near the central black hole and inflowing material. We point out what advances can be achieved by new technologies, ...
    • Multi-wavelength Observations of PKS 2142-75 during an Active Gamma-Ray State 

      Dutka, Michael; Ojha, Roopesh; Pottschmidt, Katja; Finke, Justin; Stevens, Jamie; Blanchard, Jay; Nesci, Roberto; Edwards, Philip; Lovell, Jim; Kadler, Matthias; Wilms, Joern; Tosti, Gino; Pursimo, Tapio; Fermi-LAT and TANAMI Collaborations
    • MULTI-WAVELENGTH OBSERVATIONS OF PKS 2142–75 DURING ACTIVE AND QUIESCENT GAMMA-RAY STATES 

      Dutka, Michael S.; Ojha, Roopesh; Pottschmidt, Katja; Finke, Justin D.; Stevens, Jamie; Edwards, Philip G.; Blanchard, Jay; Lovell, James E. J.; Nesci, Roberto; Kadler, Matthias; Wilms, Joern; Tosti, Gino; Pursimo, Tapio; Krauss, Felicia; Müller, Cornelia; Gehrels, Neil (IOP, 2013-12-20)
      PKS 2142–75 (a.k.a. 2FGL J2147.4–7534) is a flat-spectrum radio quasar that was observed quasi-simultaneously by a suite of instruments across the electromagnetic spectrum during two flaring states in 2010 April and 2011 ...
    • Multiband Observations of the Quasar PKS 2326–502 during Active and Quiescent Gamma-Ray States in 2010–2012 

      Dutka, Michael S.; Carpenter, Bryce D.; Ojha, Roopesh; Finke, Justin D.; D'Ammando, Filippo; Kadler, Matthias; Edwards, Philip G.; Stevens, Jamie; Torresi, Eleonora; Grandi, Paola; Nesci, Roberto; Krauß, Felicia; Müller, Cornelia; Wilms, Joern; Gehrels, Neil (IOP, 2017-02-01)
      Quasi-simultaneous observations of the Flat Spectrum Radio Quasar PKS 2326−502 were carried out in the γ-ray, X-ray, UV, optical, near-infrared, and radio bands. Using these observations, we are able to characterize the ...
    • Multiband Observations of the Quasar PKS 2326–502 during Active and Quiescent Gamma-Ray States in 2010–2012 

      Dutka, Michael S.; Carpenter, Bryce D.; Ojha, Roopesh; Finke, Justin D.; D'Ammando, Filippo; Kadler, Matthias; Edwards, Philip G.; Stevens, Jamie; Torresi, Eleonora; Grandi, Paola; Nesci, Roberto; Krauß, Felicia; Müller, Cornelia; Wilms, Joern; Gehrels, Neil (The American Astronomical Society, 2017-01-30)
      Quasi-simultaneous observations of the Flat Spectrum Radio Quasar PKS 2326−502 were carried out in the γ-ray, X-ray, UV, optical, near-infrared, and radio bands. Using these observations, we are able to characterize the ...
    • NIR and Radio follow-up of PKS0402-362 

      Nesci, Roberto; Ojha, Roopesh; Kadler, Matthias; Pursimo, Tapio; Tosti, Gino; Dutka, Michael; Blanchard, J.; Lovell, J. (2011-09-25)
    • physics, emission mechanisms, and challenges of Kiloparsec-scale Jets: 

      Perlman, Eric S.; Meyer, Eileen; Eilek, Jean; Tchekhovskoy, Sasha; Nyland, Kristina; Agudo, Ivan; Baum, Stefi; Hardcastle, Martin; Kadler, Matthias; Labiano, Alvaro; Marshall, Herman; ODea, Christopher; Worrall, Diana (2019-03-08)
      Jets are a ubiquitous part of the accretion process, created in AGN, by a coupling between the magnetic field near the central black hole and inflowing material. We point out what advances can be achieved by new technologies, ...
    • Relativistic Jets in the Accretion & Collimation Zone: New Challenges Enabled by New Instruments 

      Perlman, Eric S.; Birkinshaw, Mark; Kadler, Matthias; Komissarov, Serguei; Lister, Matthew; Meier, David; Meyer, Eileen; Nakamura, Masanori; Nyland, Kristina; O’Dea, Christopher; Worrall, Diana; Zdziarski, Andrzej (2019-02-26)
      Jets are a ubiquitous part of the accretion process, seen in a wide variety of objects ranging from active galaxies (AGN) to X-ray binary stars and even newly formed stars. AGN jets are accelerated by the supermassive black ...
    • Rising NIR and millimeter emission from VHE and Gamma-ray source PKS 0447-439 

      Nesci, Roberto; Edwards, Philip; Stevens, Jamie; Ojha, Roopesh; Dutka, Michael; Hungwe, Faith; Pursimo, Tapio; Tosti, Gino; Kadler, Matthias (2011-12-21)
    • Search for high-redshift blazars with Fermi/LAT 

      Kreter, Michael; Kadler, Matthias; Krauß, Felicia; Buson, Sara; Ojha, Roopesh; Wilms, Jörn; Böttcher, Markus; Fermi/LAT Collaboration (Proceedings of Science, 2019-07-24)
      High-redshift blazars (z ≥ 2.5) are one of the most powerful classes of γ-ray sources in the Universe. These objects possess the highest jet powers and luminosities and have black-hole masses often in excess of 10⁹ solar ...
    • Swift Follow-up of the Gamma-ray Detection of 4C +50.11 

      Krauss, Felicia; Carpenter, Bryce; Ojha, Roopesh; Kadler, Matthias; Fermi/LAT Collaboration; Wilms, Joern (2014-02-11)
    • TANAMI - Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry 

      Muller, Cornelia; Kadler, Matthias; Ojha, Roopesh; Bock, M.; Booth, R.; Dutka, M. S.; Edwards, P. G.; Fey, A. L.; Fuhrmann, L.; Hase, H.; Horiuchi, S.; Hungwe, F.; Ros, E.; Taylor, G. B.; Thompson, D. J.; Tingay, S. J.; Tosti, G.; Tzioumis, A. K.; Wilms, J.; Zensus, J. A. (2010-01-18)
      We present a summary of the observation strategy of TANAMI (Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry), a monitoring program to study the parsec-scale structure and dynamics of relativistic ...
    • TANAMI counterparts to IceCube high-energy neutrino events 

      Krauß, Felicia; Wang, Bingjie; Baxter, Claire; Kadler, Matthias; Mannheim, Karl; Ojha, Roopesh; Gräfe, Christina; Muller, Cornelia; Wilms, Joern; Carpenter, Bryce; Schulz, Robert; TANAMI Collaboration; Fermi-LAT Collaboration (arXiv, 2015-02-10)
      Since the discovery of a neutrino flux in excess of the atmospheric background by the IceCube Collaboration, searches for the astrophysical sources have been ongoing. Due to the steeply falling background towards higher ...
    • The TANAMI Program 

      Müller, Cornelia; Kadler, Matthias; Ojha, Roopesh; Böck, M.; Booth, R.; Dutka, M. S.; Edwards, P.; Fey, A. L.; Fuhrmann, L.; Hase, H.; Horiuchi, S.; Jauncey, D.L.; Johnston, K.J.; Katz, U.; Lister, M.; Lovell, J.E.J.; Plötz, C.; Quick, J.F.H.; Ros, E.; Taylor, G.B.; Thompson, D.J.; Tingay, S.J.; Tosti, G.; Tzioumis, A.K.; Wilms, J.; Zensus, J.A. (AIP Publishing, 2010-07-22)
      TANAMI (Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry) is a monitoring program to study the parsec-scale structures and dynamics of relativistic jets in active galactic nuclei (AGN) of the ...
    • VLBI studies of TANAMI radio galaxies 

      Angioni, Roberto; Rösch, Florian; Ros, Eduardo; Kadler, Matthias; Ojha, Roopesh; Müller, Cornelia; Schulz, Robert; TANAMI collaboration (2016-12-07)
      Radio galaxies are relatively faint at γ-ray energies, where they make up only 1-2% of all AGN detected by Fermi-LAT. However, they offer a unique perspective to study the intrinsic properties of AGN jets. For this reason, ...