Now showing items 680-699 of 703

    • Was the X-ray Afterglow of GRB 970815 Detected? 

      Mirabal, N.; Halpern, J. P.; Gotthelf, E. V.; Mukherjee, R. (AIP publishing, 2004-10-01)
      GRB 970815 was a well‐localized gamma‐ray burst (GRB) detected by the All‐Sky Monitor (ASM) on the Rossi X‐Ray Timing Explorer (RXTE) for which no afterglow was identified despite follow‐up ASCA and ROSAT pointings and ...
    • A weakening Compton hump and soft X-ray excess detected in the Seyfert-1 galaxy MCG-02-58-22 

      Laha, Sibasish; Ghosh, Ritesh (IOP Publishing, 2021-04-29)
      We have carried out an extensive X-ray spectral study of the bare Seyfert-1 galaxy MCG--02--58--22 to ascertain the nature of the X-ray reprocessing media, using observations from Suzaku (2009) and simultaneous observations ...
    • The WEBT Campaign on the Blazar 3C 279 in 2006 

      Mirabal, N.; et al. (IOP, 2007-08-16)
      The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from 2006 January through April. An optical-IR-radio monitoring campaign by the Whole Earth Blazar Telescope (WEBT) collaboration was ...
    • What can Fermi tell us about CTA? 

      Garcıa, R.; Curras, E.; Mirabal, N.; Contreras, J.L.; Carmona, E. (2010-09)
    • What is the nature and origin of the highest-energy particles in the universe 

      Sarazin, Fred; Anchordoqui, Luis; Beatty, James; Bergman, Douglas; Covault, Corbin; Farrar, Glennys; Krizmanic, John; Nitz, David; Olinto, Angela; Unger, Michael; Tinyakov, Peter; Wiencke, Lawrence (2019-03-10)
      This white paper was submitted to the US Astronomy and Astrophysics Decadal Survey (Astro2020) and defines the science questions to be answered in the next decade in the field of Ultra-High Energy Cosmic-Rays. Following a ...
    • What is the Structure of Relativistic Jets in AGN on Scales of Light Days? 

      Zacharias, Norbert; Johnston, Kenneth; Boboltz, David; Fey, Alan L.; Gaume, Ralph; Ojha, Roopesh; Meier, David L.; Murphy, David W.; Jones, Dayton L.; Unwin, Stephen C.; Piner, B. Glenn (2009-02-11)
      The structure of relativistic jets in AGN on scales of light days reveals how energy propagates through jets, a process that is fundamental to galaxy evolution. A deeper understanding of jet physics will clarify the ...
    • The White Dwarf Mass versus X-Ray Temperature Relationship of Dwarf Novae, Revisited 

      Mukai, Koji; Byckling, Kristiina (IOP Science, 2022-03)
      While Keplerian orbits account for the majority of the astrometric motion of directly-imaged planets, perturbations due to N-body interactions allow us to directly constrain exoplanet masses in multiplanet systems. This ...
    • White light flare rates of M5-L5 dwarfs using K2 data 

      Paudel, Rishi R; Gizis, J. E.; Mullan, D. J.; Schmidt, S. J.; Burgasser, A. J.; Williams, P. K. G. (2018-11-15)
      The K2 mission’s unique combination of wide area coverage and continuous time coverage over months has enabled us to study white light flare rates of cool stars of various spectral types. We have shown that the white light ...
    • WHY DO COMPACT ACTIVE GALACTIC NUCLEI AT HIGH REDSHIFT SCINTILLATE LESS? 

      Koay, J. Y.; Macquart, J-P.; Rickett, B. J.; Bignall, H. E.; Jauncey, D. L.; Pursimo, T.; Reynolds, C.; Lovell, J. E. J.; Kedziora-Chudczer, L.; Ojha, R. (IOP, 2012-08-12)
      The fraction of compact active galactic nuclei (AGNs) that exhibit interstellar scintillation (ISS) at radio wavelengths, as well as their scintillation amplitudes, have been found to decrease significantly for sources at ...
    • Willman 1: An X-ray shot in the dark with Chandra 

      Nieto, D.; Mirabal, N. (2010-03-19)
      The sterile neutrino is a weakly-interacting particle that emerges in the framework of certain extensions of standard particle physics and that fits naturally with the properties of a warm dark matter particle candidate. ...
    • WISEP J060738.65+242953.4: A Nearby. Pole-On L8 Brown Dwarf with Radio Emission 

      Gizis, John E.; Williams, Peter K. G.; Burgasser, Adam J.; Libralato, Mattia; Nardiello, Domenico; Piotto, Giampaolo; Bedin, Luigi R.; Berger, Edo; Paudel, Rishi R. (IOP, 2016-10-19)
      We present a simultaneous, multi-wavelength campaign targeting the nearby (7.2 pc) L8/L9 (optical/near-infrared) dwarf WISEP J060738.65+242953.4 in the mid-infrared, radio, and optical. Spitzer Space Telescope observations ...
    • The X-Ray Afterglow of Dark GRB 970815: A Common Origin for Gamma-Ray Bursts and X-Ray Flashes? 

      Mirabal, N.; Halpern, J. P.; Gotthelf, E. V.; Mukherjee, R. (IOP, 2004-10-25)
      GRB 970815 is a well-localized gamma-ray burst (GRB) detected by the All-Sky Monitor (ASM) on the Rossi X-Ray Timing Explorer (RXTE) for which no afterglow was identified despite follow-up ASCA and ROSAT pointings and ...
    • X-Ray and GeV Gamma-Ray Variability of the Radio Galaxy NGC 1275 

      Fukazawa, Yasushi; Shiki, Kensei; Tanaka, Yasuyuki; Itoh, Ryosuke; Takahashi, Hiromitsu; Imazato, Fumiya; Dutka, Filippo; Ojha, Roopesh; Nagai, Hiroshi (IOP, 2018-03-12)
      We analyzed Suzaku/XIS data (2006–2015) and Fermi/LAT data (2008–2015) of the gamma-ray emitting radio galaxy NGC 1275. Correlated brightening of the nucleus in both the X-ray and GeV gamma-ray energy bands was found for ...
    • X-Ray Binary Luminosity Function Scaling Relations for Local Galaxies Based on Subgalactic Modeling 

      Lehmer, Bret D.; Eufrasio, Rafael T.; Tzanavaris, Panayiotis; Basu-Zych, Antara; Fragos, Tassos; Prestwich, Andrea; Yukita, Mihoko; Zezas, Andreas; Hornschemeier, Ann E.; Ptak, Andrew (The American Astronomical Society, 2019-06-26)
      We present new Chandra constraints on the X-ray luminosity functions (XLFs) of X-ray binary (XRB) populations, as well as their scaling relations, for a sample of 38 nearby galaxies (D = 3.4–29 Mpc). Our galaxy sample ...
    • X-ray Binary Luminosity Function Scaling Relations in Elliptical Galaxies: Evidence for Globular Cluster Seeding of Low-Mass X-ray Binaries in Galactic Fields 

      Lehmer, Bret D.; Ferrell, Andrew P.; Doore, Keith; Eufrasio, Rafael T.; Monson, Erik B.; Alexander, David M.; Basu-Zych, Antara; Brandt, William N.; Sivakoff, Greg; Tzanavaris, Panayiotis; Yukita, Mihoko; Fragos, Tassos; Ptak, Andrew (2020-04-27)
      We investigate X-ray binary (XRB) luminosity function (XLF) scaling relations for Chandra detected populations of low-mass XRBs (LMXBs) within the footprints of 24 early-type galaxies. Our sample includes Chandra and HST ...
    • X-ray emission from magnetized neutron star atmospheres at low mass accretion rates. I. Phase-averaged spectrum 

      Sokolova-Lapa, E.; Gornostaev, M.; Wilms, J.; Ballhausen, R.; Falkner, S.; Postnov, K.; Thalhammer, P.; Fürst, F.; García, J. A.; Shakura, N.; Becker, P. A.; Wolff, M. T.; Pottschmidt, Katja; Härer, L.; Malacaria, C.
      Recent observations of X-ray pulsars at low luminosities allow, for the first time, to compare theoretical models for the emission from highly magnetized neutron star atmospheres at low mass accretion rates (M˙≲1015 g s−1) ...
    • X-ray evolution of the nova V959 Mon suggests a delayed ejection and a non-radiative shock 

      Nelson, Thomas; Mukai, Koji; Chomiuk, Laura; Sokoloski, Jennifer L.; Linford, Justin D.; Finzell, Thomas; Mioduszewski, Amy J.; Rupen, Michael P.; Weston, Jennifer; Oliveira, Raimundo Lopes de (2020-07-30)
      X-ray observations of shocked gas in novae can provide a useful probe of the dynamics of the ejecta. Here we report on X-ray observations of the nova V959 Mon, which was also detected in GeV gamma-rays with the Fermi ...
    • X-ray imaging tests of Constellation-X SXT mirror segment pairs 

      Rohrbach, S. Owens; Hadjimichael, T. J.; Olsen, L.; Chan, Kai-Wing; Lehan, J. P.; Reid, P. B.; Petre, R.; O'Dell, S. L.; Saha, T. T.; Zhang, W. W. (SPIE, 2008-07-15)
      The Constellation-X Spectroscopy X-ray Telescope (SXT) is a segmented, tightly nested Wolter-I telescope with a requirement of approximately 12.5 arcseconds HPD for the mirror system. The individual mirror segments are 0.4 ...
    • X-ray monitoring of the radio and γ-ray loud Narrow-Line Seyfert 1 Galaxy PKS2004–447 

      Kreikenbohm, A.; Kadler, M.; Wilms, J.; Schulz, R.; Müller, C.; Ojha, R.; Ros, E.; Mannheim, K.; Elsässer, D. (EDP sciences, 2013-12-09)
      We present preliminary results of the X-ray analysis of XMM-Newton and Swift observations as part of a multi-wavelength monitoring campaign in 2012 of the radio-loud narrow line Seyfert 1 galaxy PKS 2004–447. The source ...
    • An X-ray spectral study of the origin of reflection features in bare Seyfert 1 galaxy ESO 511--G030 

      Ghosh, Ritesh; Laha, Sibasish (2020-12-19)
      The reprocessed X-ray emission from Active Galactic Nuclei (AGN) is an important diagnostic tool to study the dynamics and geometry of the matter surrounding the supermassive black holes (SMBHs). We present a broadband ...