Now showing items 61-80 of 883

    • BICEP3: A 95GHz Refracting Telescope for Degree-Scale CMB Polarization 

      Ahmed, Z.; Amiri, M.; Benton, S. J.; Bock, J. J.; Bowens-Rubin, R; Buder, I; Bullock, E.; Connors, Jake Anthony; Filippini, J. P.; Grayson, J. A.; Halpern, M.; Hilton, G. C.; Hristov, V. V.; Hui, H.; Irwin, K. D.; Kang, J.; Karkare, Kirit Sukrit; Karpel, E.; Kovac, John M; Kuo, C. L.; Netterfield, C. B.; Nguyen, H. T.; O, R.; Ogburn, R. W.; Pryke, C; Reintsema, C. D.; Richter, Sonja Valeska; Thompson, K. L.; Turner, A. D.; Vieregg, A. G.; Wu, W. L. K.; Yoon, K. W. (International Society for Optics and Photonics, 2014)
      Bicep3 is a 550 mm-aperture refracting telescope for polarimetry of radiation in the cosmic microwave background at 95 GHz. It adopts the methodology of Bicep1, Bicep2 and the Keck Array experiments — it possesses sufficient ...
    • Birth of a relativistic outflow in the unusual γ-ray transient Swift J164449.3+573451 

      Zauderer, Bevin Ashley; Berger, Edo; Soderberg, Alicia M.; Loeb, Abraham; Narayan, Ramesh; Frail, D. A.; Petitpas, Glen Raymond; Brunthaler, A.; Chornock, Ryan T.; Carpenter, J. M.; Pooley, G. G.; Mooley, K.; Kulkarni, S. R.; Margutti, Raffaella; Fox, D. B.; Nakar, E.; Patel, Nimesh A.; Volgenau, N. H.; Culverhouse, T. L.; Bietenholz, M. F.; Rupen, M. P.; Max-Moerbeck, W.; Readhead, A. C. S.; Richards, J.; Shepherd, M.; Storm, S.; Hull, Charles L. H. (Springer Nature, 2011)
      Active galactic nuclei, which are powered by long-term accretion onto central supermassive black holes, produce1 relativistic jets with lifetimes of at least one million years, and the observation of the birth of such a ...
    • The Black Hole Mass Distribution in the Galaxy 

      Özel, Feryal; Psaltis, Dimitrios; Narayan, Ramesh; McClintock, Jeffrey E. (IOP Publishing, 2010)
      We use dynamical mass measurements of 16 black holes in transient low-mass X-ray binaries to infer the stellar black hole mass distribution in the parent population. We find that the observations are best described by a ...
    • Black Hole Spin and the Radio Loud/Quiet Dichotomy of Active Galactic Nuclei 

      Tchekhovskoy, Alexander; Narayan, Ramesh; McKinney, Jonathan C. (IOP Publishing, 2010)
      Radio loud active galactic nuclei (AGNs) are on average 1000 times brighter in the radio band compared to radio quiet AGNs. We investigate whether this radio loud/quiet dichotomy can be due to differences in the spin of ...
    • Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets 

      McClintock, Jeffrey E.; Narayan, Ramesh; Steiner, James (Springer Science + Business Media, 2013)
      The spins of ten stellar black holes have been measured using the continuum- fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another ...
    • The Black-Hole Accretion Disk in NGC 4258: One of Nature’s Most Beautiful Dynamical Systems 

      Moran, James M. (Astronomical Society of the Pacific, 2008)
      In this talk I will summarize some of the work that the CfA group has done to study the structure of the water masers in the accretion disk of NGC4258. A series of 18 epochs of VLBA data taken from 1997.3 to 2000.8 were ...
    • Blackbody Radiation From Isolated Neptunes 

      Ginzburg, Sivan; Sari, Re’em; Loeb, Abraham (American Astronomical Society, 2016)
      Recent analyses of the orbits of some Kuiper Belt objects hypothesize the presence of an undiscovered Neptune-size planet at a very large separation from the Sun. The energy budget of Neptunes on such distant orbits is ...
    • The Blue Tip of the Stellar Locus: Measuring Reddening with the Sloan Digital Sky Survey 

      Schlafly, Edward F.; Finkbeiner, Douglas; Schlegel, David J.; Juric, Mario; Ivezic, Zeljko; Gibson, Robert R.; Knapp, Gillian R.; Weaver, Benjamin A. (IOP Publishing, 2010)
      We present measurements of reddening due to dust using the colors of stars in the Sloan Digital Sky Survey (SDSS). We measure the color of main-sequence turnoff stars by finding the "blue tip" of the stellar locus: the ...
    • Bondi Flow from a Slowly Rotating Hot Atmosphere 

      Narayan, Ramesh; Fabian, Andrew C. (Oxford University Press (OUP), 2011)
      A supermassive black hole in the nucleus of an elliptical galaxy at the centre of a cool-core group or cluster of galaxies is immersed in hot gas. Bondi accretion should occur at a rate determined by the properties of the ...
    • The Bones of the Milky Way 

      Goodman, Alyssa; Alves, Joao; Beaumont, Christopher N; Benjamin, Robert A.; Borkin, Michelle A; Burket, Andreas; Dame, Thomas M.; Jackson, James; Kauffmann, Jens; Robitaille, Thomas (American Astronomical Society, 2013)
      The very long, thin infrared dark cloud "Nessie" is even longer than had been previously claimed, and an analysis of its Galactic location suggests that it lies directly in the Milky Way’s mid-plane, tracing out a highly ...
    • Building A Three Dimensional Universe From The Classroom: Multiperspective Visualization For Non-science Undergraduates 

      Ladd, E; Udomprasert, Patricia S; Nottis, Kathryn E. K.; Goodman, Alyssa (2016)
      We develop three-dimensional mental models of our physical environs from two dimensional imagery we collect with our eyes. This is possible only because we move through that environment, viewing it from multiple perspectives, ...
    • C/o and Snowline Locations in Protoplanetary Disks: The Effect of Radial Drift and Viscous Gas Accretion 

      Piso, Ana-Maria Adriana; Oberg, Karin; Birnstiel, Tilman David; Murray-Clay, Ruth Ann (IOP Publishing, 2015)
      The C/O ratio is a defining feature of both gas giant atmospheric and protoplanetary disk chemistry. In disks, the C/O ratio is regulated by the presence of snowlines of major volatiles at different distances from the ...
    • Calibration of an Astrophysical Spectrograph Below 1 m/s Using a Laser Frequency Comb 

      Phillips, David Forrest; Glenday, Alexander G.; Li, Chih-Hao; Cramer, Claire; Furesz, Gabor; Chang, Guoqing; Benedick, Andrew J.; Chen, Li-Jin; Szentgyorgyi, Andrew H.; Walsworth, Ronald L. (Optical Society of America, 2012)
      We deployed two wavelength calibrators based on laser frequency combs (“astro-combs”) at an astronomical telescope. One astro- comb operated over a 100 nm band in the deep red (∼ 800 nm) and a second operated over a 20 nm ...
    • Calibration of the MEarth Photometric System: Optical Magnitudes and Photometric Metallicity Estimates for 1802 Nearby M-dwarfs 

      Dittmann, Jason Adam; Irwin, Jonathan; Charbonneau, David; Newton, Elisabeth R (American Astronomical Society, 2016)
      The MEarth Project is a photometric survey systematically searching the smallest stars nearest to the Sun for transiting rocky planets. Since 2008, MEarth has taken approximately two million images of 1844 stars suspected ...
    • The Cambridge-Cambridge ROSAT Serendipity Survey - III. VLA observations and the evolution of radio-quiet and radio-loud objects 

      Ciliegi, P.; Elvis, Martin S.; Wilkes, Belinda Jane; Boyle, B. J.; McMahon, R. G.; Maccacaro, T. (Oxford University Press (OUP), 1995)
      We present the results of the VLA radio observations at 1.475 GHz (20 cm) of the active galactic nuclei (AGN) in the Cambridge-Cambridge ROSAT Serendipity Survey (CRSS), a sample of 123 faint X-ray sources with ...
    • The Cambridge-Cambridge ROSAT Serendipity Survey -- IV. The X-ray properties 

      Ciliegi, P.; Elvis, Martin S.; Wilkes, Belinda Jane; Boyle, B. J.; McMahon, R. G. (Oxford University Press (OUP), 1997)
      We present a detailed X-ray spectral analysis in the 0.1–2.4 keV ROSAT band of a complete sample of X-ray-selected AGN using the 80 AGNs in the Cambridge-Cambridge ROSAT Serendipity Survey (68 QSOs and 12 narrow-emission-line ...
    • The Cambridge-Cambridge ROSAT Serendipity Survey -- V. Catalogue and optical identifications 

      Boyle, B. J.; Wilkes, Belinda Jane; Elvis, Martin S. (Oxford University Press (OUP), 1997)
      We report the results of a medium-depth X-ray survey of 20 ROSAT Position Sensitive Proportional Counter (PSPC) fields. 123 X-ray sources were detected down to a flux limit of S(0.5–2 keV) > 2 × 10−14 erg s−1 cm−2 lying ...
    • The Cambridge–Cambridge ROSAT Serendipity Survey – II. Classification of X-ray-luminous Galaxies 

      Boyle, B.J.; McMahon, R.G.; Wilkes, Belinda Jane; Elvis, Martin S. (Royal Astronomical Society, 1995)
      We present the results of an intermediate-resolution (1.5\AA) spectroscopic study of 17 X-ray luminous narrow emission-line galaxies previously identified in the Cambridge-Cambridge {\it ROSAT} Serendipity Survey and the ...
    • Case for a700+GeVWIMP: Cosmic ray spectra from PAMELA, Fermi, and ATIC 

      Cholis, Ilias; Dobler, Gregory; Finkbeiner, Douglas; Goodenough, Lisa; Weiner, Neal (American Physical Society (APS), 2009)
      Multiple lines of evidence indicate an anomalous injection of high-energy e+- in the Galactic halo. The recent e+ fraction spectrum from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) ...
    • Cataclysmic Variables Discovered in the Chandra Multi-Wavelength Plane Survey 

      Zhao, Ping; Grindlay, Jonathan E.; Hong, Jaesub; Servillat, M.; van den Berg, M. (Fabrizio Serra editore, 2013)
      We present 25 cataclysmic variables discovered in the Chandra Multi-wavelength Plane Survey (ChaMPlane: Grindlay et al. (2005); Hong et al. (2005); Zhao et al. (2005)), which is designed to investigate the nature of the ...