Browsing UMBC Physics Department by Author "Ojha, Roopesh"

Accurate Astrometry of 22 Southern Hemisphere Radio Sources

Fey, Alan L.; Ojha, Roopesh; Jauncey, David L.; Johnston, Kenneth J.; Reynolds, John E.; Lovell, James E. J.; Tzioumis, Anastasios K.; Quick, Jonathan F. H.; Nicolson, George D.; Ellingsen, Simon P.; McCulloch, Peter M.; Koyama, Yasuhiro (IOP, 2003-12-03)

Milliarcsecond-accurate radio positions for 22 southern hemisphere extragalactic sources are reported. These positions are derived from Mark III very long baseline interferometry observations made between 2003 February and ...

AGN TXS 1923+123

Carpenter, Bryce; Ojha, Roopesh (The Astronomer's Telegram, 2016-01-01)

Angular Broadening of Intraday Variable AGNs. II. Interstellar and Intergalactic Scattering

Lazio, T. Joseph W.; Ojha, Roopesh; Fey, Alan L.; Kedziora-Chudczer, Lucyna; Cordes, James M.; Jauncey, David L.; Lovell, James E. J. (IOP, 2008-01-01)

We analyze a sample of 58 multiwavelength, Very Long Baseline Array observations of active galactic nuclei (AGNs) to determine their scattering properties. Approximately 75% of the sample consists of AGNs that ...

The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)

Stark, Antony A.; Bally, John; Balm, Simon P.; Bania, T. M.; Bolatto, Alberto D.; Chamberlin, Richard A.; Engargiola, Gregory; Huang, Maohai; Ingalls, James G.; Jacobs, Karl; Jackson, James M.; Kooi, Jacob W.; Lane, Adair P.; Lo, K.-Y.; Marks, Rodney D.; Martin, Christopher L.; Mumma, Dennis; Ojha, Roopesh; Schieder, Rudolf; Staguhn, Johannes; Stutzki, Juergen; Walker, Christopher K.; Wilson, Robert W.; Wright, Gregory A.; Zhang, Xiaolei; Zimmermann, Peter; Zimmermann, Ruediger (IOP, 2000-12-15)

AST/RO, a 1.7 m diameter telescope for astronomy and aeronomy studies at wavelengths between 200 and 2000 microns, was installed at the South Pole during the 1994-1995 Austral summer. The telescope operates continuously ...

AST/RO Observations of Atomic Carbon near the Galactic Center

Ojha, Roopesh; Stark, Antony A.; Hsieh, Henry H.; Lane, Adair P.; Chamberlin, Richard A.; Bania, Thomas M.; Bolatto, Alberto D.; Jackson, James M.; Wright, Gregory A. (IOP, 2001-02-10)

We present a coarsely sampled map of the region |l| ≤ 2°, |b| ≤ 0°1 in the 492 GHz (³P₁ → ³P₀) fine-structure transition of neutral carbon, observed with the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO). ...

Astrometry of 25 Southern Hemisphere Radio Sources from a VLBI Short-Baseline Survey

Fey, Alan L.; Ojha, Roopesh; Reynolds, John E.; Ellingsen, Simon P.; McCulloch, Peter M.; Jauncey, David L.; Johnston, Kenneth J. (IOP, 2004-11)

Milliarcsecond-accurate radio positions for 25 southern hemisphere extragalactic sources are reported. These positions are derived from Mark III Very Long Baseline Interferometry observations made between 2003 September ...

ATCA Observations of the New Gamma-ray Source PKS 1824-582

Edwards, Philip G.; Stevens, Jamie; Ojha, Roopesh (2014-04-17)

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 ...

Coincidence of a high-fluence blazar outburst with a PeV-energy neutrino event

Ojha, Roopesh; et al. (Nature, 2016-04-18)

The astrophysical sources of the extraterrestrial, very high-energy neutrinos detected by the IceCube collaboration remain to be identified. Gamma-ray (γ-ray) blazars have been predicted to yield a cumulative neutrino ...

Elevated fluxes at multiple radio frequencies seen in flaring blazar PKS 0454-234

Gaylard, Michael; West, Marion; Edwards, Philip; Stevens, Jamie; Ojha, Roopesh; Hungwe, Faith (2011-10-26)

Elevated radio fluxes in flaring FSRQ PKS 0502+049

Edwards, Philip G.; Stevens, Jamie; Ojha, Roopesh (2013-03-07)

Energetic Particles of Cosmic Accelerators I: Galactic Accelerators

Venters, Tonia M.; Hamaguchi, Kenji; Ojha, Roopesh

The high-energy universe has revealed that energetic particles are ubiquitous in the cosmos and play a vital role in the cultivation of cosmic environments on all scales. Our pursuit of more than a century to uncover the ...

Energetic Particles of Cosmic Accelerators II: Active Galactic Nuclei and Gamma-ray Bursts

Venters, Tonia M.; Guiriec, Sylvain; Lien, Amy Y.; Ojha, Roopesh

The high-energy universe has revealed that energetic particles are ubiquitous in the cosmos and play a vital role in the cultivation of cosmic environments on all scales. Our pursuit of more than a century to uncover the ...

Fermi and Swift observations of the new unidentified gamma-ray point source Fermi J1418+3541

Dutka, Michael; Ojha, Roopesh; Tanaka, Yasuyuki; Sokolovsky, Kirill; Fermi LAT Collaboration (Dutka, Michael; Ojha, Roopesh; Tanaka, Yasuyuki; Sokolovsky, Kirill; Fermi LAT Collaboration; Fermi and Swift observations of the new unidentified gamma-ray point source Fermi J1418+3541; http://www.astronomerstelegram.org/?read=4643, 2012-12-12)