Now showing items 2821-2840 of 18256

    • Constraining the Beaming of Gamma-Ray Bursts with Radio Surveys 

      Perna, Rosalba; Loeb, Abraham (American Astronomical Society, 1998)
      The degree of beaming in gamma-ray bursts (GRBs) is currently unknown. The uncertainty in the gamma-ray-beaming angle, theta(b), leaves the total energy release (proportional to theta(b)(2)) and the event rate per galaxy ...
    • Constraining the CMB optical depth through the dispersion measure of cosmological radio transients 

      Fialkov, Anastasia; Loeb, Abraham (IOP Publishing, 2016)
      The dispersion measure of extragalactic radio transients, such as of recently discovered Fast Radio Burst FRB150418, can be used to measure the column density of free electrons in the intergalactic medium. The same electrons ...
    • Constraining the Collisional Nature of the Dark Matter Through Observations of Gravitational Wakes 

      Furlanetto, Steven R.; Loeb, Abraham (American Astronomical Society, 2001)
      We propose to use gravitational wakes as a direct observational probe of the collisional nature of the dark matter. We calculate analytically the structure of a wake generated by the motion of a galaxy in the core of an ...
    • Constraining the Milky Way mass with hypervelocity stars 

      Fragione, G.; Loeb, Abraham (Elsevier BV, 2017)
      Context. Although a variety of techniques have been employed for determining the Milky Way dark matter halo mass distribution, the range of allowed masses spans both light and heavy values. Knowing the precise mass of our ...
    • Constraining the Minimum Mass of High-redshift Galaxies and Their Contribution to the Ionization State of the Intergalactic Medium 

      Muñoz, J. A.; Loeb, A. (American Astronomical Society, 2011)
      We model the latest HST WFPC3/IR observations of greater than or similar to 100 galaxies at redshifts z = 7-8 in terms of a hierarchical galaxy formation model with starburst activity. Our model provides a distribution of ...
    • Constraining the Nature of the Galactic Center X-Ray Source Population 

      Laycock, S.; Grindlay, J.; van den Berg, M.; Zhao, P.; Hong, J.; Koenig, X.; Schlegel, E. M.; Persson, S. E. (American Astronomical Society, 2005)
      We searched for infrared counterparts to the cluster of X-ray point sources discovered by Chandra in the Galactic center region (GCR). While the sources could be white dwarfs, neutron stars, or black holes accreting from ...
    • Constraining the quasar population with the broad-line width distribution 

      Fine, S.; Croom, S. M.; Hopkins, P. F.; Hernquist, L.; Bland-Hawthorn, J.; Colless, M.; Hall, P. B.; Miller, L.; Myers, A. D.; Nichol, R.; Pimbblet, K. A.; Ross, N. P.; Schneider, D. P.; Shanks, T.; Sharp, R. G. (Oxford University Press, 2008-10-27)
      In this work, we test the assertion that the scatter in the mass of black holes which drive quasars should be luminosity dependent with less scatter in more luminous objects. To this end, we measure the width of the Mg II ...
    • Constraining the Stellar Mass Function in the Galactic Center via Mass Loss from Stellar Collisions 

      Rubin, Douglas; Loeb, Abraham (Hindawi, 2011)
      The dense concentration of stars and high-velocity dispersions in the Galactic center imply that stellar collisions frequently occur. Stellar collisions could therefore result in significantmass loss rates. We calculate ...
    • Constraining the Structure of Sagittarius A*'s Accretion Flow with Millimeter Very Long Baseline Interferometry Closure Phases 

      Broderick, Avery E.; Fish, Vincent L.; Doeleman, Sheperd S.; Loeb, Abraham (American Astronomical Society, 2011)
      Millimeter wave very long baseline interferometry (mm-VLBI) provides access to the emission region surrounding Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, on sub-horizon scales. ...
    • Constraining the topology of reionization through Lyα absorption 

      Furlanetto, S. R.; Hernquist, L.; Zaldarriaga, M. (Oxford University Press, 2004)
      The reionization of hydrogen in the intergalactic medium (IGM) is a crucial landmark in the history of the Universe, but the processes through which it occurs remain mysterious. In particular, recent numerical and analytic ...
    • Constraining the unexplored period between the dark ages and reionization with observations of the global 21 cm signal 

      Pritchard, Jonathan R.; Loeb, Abraham (American Physical Society, 2010)
      Observations of the frequency dependence of the global brightness temperature of the redshifted 21 cm line of neutral hydrogen may be possible with single dipole experiments. In this paper, we develop a Fisher matrix ...
    • Constraining the X-ray and cosmic ray ionization chemistry of the TW Hya protoplanetary disk: evidence for a sub-interstellar cosmic-ray rate. 

      Cleeves, Lauren Ilsedore; Bergin, Edwin A.; Qi, Chunhua; Adams, Fred C.; Oberg, Karin (IOP Publishing, 2015)
      We present an observational and theoretical study of the primary ionizing agents (cosmic rays and X-rays) in the TW Hya protoplanetary disk. We use a set of resolved and unresolved observations of molecular ions and other ...
    • Constraints from 210 Pb and 7 Be on wet deposition and transport in a global three-dimensional chemical tracer model driven by assimilated meteorological fields 

      Liu, Hongyu; Jacob, Daniel James; Bey, Isabelle; Yantosca, Robert M. (Wiley-Blackwell, 2001)
      The atmospheric distributions of the aerosol tracers 210Pb and 7Be are simulated with a global three-dimensional model driven by assimilated meteorological observations for 1991–1996 from the NASA Goddard Earth Observing ...
    • Constraints from the Hubble Deep Field on High‐Redshift Quasar Models 

      Haiman, Zoltan; Madau, Piero; Loeb, Abraham (American Astronomical Society, 1999)
      High-resolution, deep-imaging surveys are instrumental in setting constraints on semianalytical structure formation models in cold dark matter (CDM) cosmologies. We show here that the lack of unresolved B-band "dropouts" ...
    • Constraints Imposed by Non-Functional Protein–Protein Interactions on Gene Expression and Proteome Size 

      Zhang, Jingshan; Maslov, Sergei; Shakhnovich, Eugene Isaacovitch (Nature Publishing Group, 2008)
      Crowded intracellular environments present a challenge for proteins to form functional specific complexes while reducing non-functional interactions with promiscuous non-functional partners. Here we show how the need to ...
    • Constraints on Asian and European sources of methane from CH 4 -C 2 H 6 -CO correlations in Asian outflow 

      Xiao, Yaping; Jacob, Daniel James; Wang, James; Logan, Jennifer A.; Palmer, Paul; Suntharalingam, Parvadha; Yantosca, Robert M.; Sachse, Glen; Blake, Donald; Streets, David (Wiley-Blackwell, 2004)
      Aircraft observations of Asian outflow from the Transport and Chemical Evolution Over the Pacific (TRACE-P) aircraft mission over the NW Pacific (March and April 2001) show large CH4 enhancements relative to background, ...
    • Constraints on Black Hole Growth, Quasar Lifetimes, and Eddington Ratio Distributions From the Sdss Broad-line Quasar Black Hole Mass Function 

      Kelly, Brandon C.; Vestergaard, Marianne; Fan, Xiaohui; Hopkins, Philip; Hernquist, Lars; Siemiginowska, Aneta (American Astronomical Society, 2010)
      We present an estimate of the black hole mass function of broad-line quasars (BLQSOs) that self-consistently corrects for incompleteness and the statistical uncertainty in the mass estimates, based on a sample of 9886 ...
    • Constraints on cold magnetized shocks in gamma-ray bursts 

      Narayan, Ramesh; Kumar, Pawan; Tchekhovskoy, Alexander (Oxford University Press (OUP), 2011)
      We consider a model in which the ultra-relativistic jet in a gamma-ray burst (GRB) is cold and magnetically accelerated. We assume that the energy flux in the outflowing material is partially thermalized via internal shocks ...
    • Constraints on Cosmological Parameters from the Ly? Forest Power Spectrum and COBE DMR 

      Phillips, John; Weinberg, David H.; Croft, Rupert A. C.; Hernquist, Lars; Katz, Neal; Pettini, Max (American Astronomical Society, 2001)
      We combine COBE DMR measurements of cosmic microwave background (CMB) anisotropy with a recent measurement of the mass power spectrum at redshift z = 2.5 from Ly alpha forest data to derive constraints on cosmological ...
    • Constraints on large extra dimensions from the MINOS experiment 

      Adamson, P.; Anghel, I.; Aurisano, A.; Barr, G.; Bishai, M.; Blake, A.; Bock, G. J.; Bogert, D.; Cao, S. V.; Carroll, T. J.; Castromonte, C. M.; Chen, R.; Childress, S.; Coelho, J. A. B.; Corwin, L.; Cronin-Hennessy, D.; de Jong, J. K.; De Rijck, S.; Devan, A. V.; Devenish, N. E.; Diwan, M. V.; Escobar, C. O.; Evans, J. J.; Falk, E.; Feldman, Gary J.; Flanagan, W.; Frohne, M. V.; Gabrielyan, M.; Gallagher, H. R.; Germani, S.; Gomes, R. A.; Goodman, M. C.; Gouffon, P.; Graf, N.; Gran, R.; Grzelak, K.; Habig, A.; Hahn, S. R.; Hartnell, J.; Hatcher, R.; Holin, A.; Huang, J.; Hylen, J.; Irwin, G. M.; Isvan, Z.; James, C.; Jensen, D.; Kafka, T.; Kasahara, S. M. S.; Koizumi, G.; Kordosky, M.; Kreymer, A.; Lang, K.; Ling, J.; Litchfield, P. J.; Lucas, P.; Mann, W. A.; Marshak, M. L.; Mayer, N.; McGivern, C.; Medeiros, M. M.; Mehdiyev, R.; Meier, J. R.; Messier, M. D.; Miller, W. H.; Mishra, S. R.; Moed Sher, S.; Moore, C. D.; Mualem, L.; Musser, J.; Naples, D.; Nelson, J. K.; Newman, H. B.; Nichol, R. J.; Nowak, J. A.; O’Connor, J.; Orchanian, M.; Pahlka, R. B.; Paley, J.; Patterson, R. B.; Pawloski, G.; Perch, A.; Pfützner, M. M.; Phan, D. D.; Phan-Budd, S.; Plunkett, R. K.; Poonthottathil, N.; Qiu, X.; Radovic, A.; Rebel, B.; Rosenfeld, C.; Rubin, H. A.; Sail, P.; Sanchez, M. C.; Schneps, J.; Schreckenberger, A.; Schreiner, P.; Sharma, R.; Sousa, A.; Tagg, N.; Talaga, R. L.; Thomas, J.; Thomson, M. A.; Tian, X.; Timmons, A.; Todd, J.; Tognini, S. C.; Toner, R; Torretta, D.; Tzanakos, G.; Urheim, J.; Vahle, P.; Viren, B.; Weber, A.; Webb, R. C.; White, C.; Whitehead, L.; Whitehead, L. H.; Wojcicki, S. G.; Zwaska, R. (American Physical Society (APS), 2016)
      We report new constraints on the size of large extra dimensions from data collected by the MINOS experiment between 2005 and 2012. Our analysis employs a model in which sterile neutrinos arise as Kaluza-Klein states in ...