Topic
White dwarf
About: White dwarf is a research topic. Over the lifetime, 15004 publications have been published within this topic receiving 430597 citations. The topic is also known as: degenerate dwarf.
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Fermilab1, Stanford University2, University of Chicago3, Texas A&M University4, Stockholm University5, University of Pisa6, Stony Brook University7, Centre national de la recherche scientifique8, Royal Swedish Academy of Sciences9, Istituto Nazionale di Fisica Nucleare10, University of California, Santa Cruz11, University of Perugia12, University of Udine13, University of Bari14, Goddard Space Flight Center15, University of Göttingen16, Hiroshima University17, Purdue University18, University of Nova Gorica19, University of Trieste20, Space Telescope Science Institute21, University of Surrey22, Spanish National Research Council23, University College London24, Carnegie Institution for Science25, University of Pennsylvania26, Institut d'Astrophysique de Paris27, SLAC National Accelerator Laboratory28, Institut de Ciències de l'Espai29, National Center for Supercomputing Applications30, Institute of Cosmology and Gravitation, University of Portsmouth31, Ludwig Maximilian University of Munich32, California Institute of Technology33, University of Michigan34, Catalan Institution for Research and Advanced Studies35, Autonomous University of Barcelona36, Max Planck Society37, University of Illinois at Urbana–Champaign38, Ohio State University39, Santa Cruz Institute for Particle Physics40, Argonne National Laboratory41, Australian Astronomical Observatory42, Universidade Federal do Rio Grande do Sul43, Brookhaven National Laboratory44, University of Sussex45, University of Manchester46
TL;DR: In this article, the authors search for gamma-ray emission coincident with the positions of these new objects in six years of Fermi Large Area Telescope data and find no significant excesses of gamma radiation emission.
Abstract: Due to their proximity, high dark-matter (DM) content, and apparent absence of non-thermal processes, Milky Way dwarf spheroidal satellite galaxies (dSphs) are excellent targets for the indirect detection of DM. Recently, eight new dSph candidates were discovered using the first year of data from the Dark Energy Survey (DES). We searched for gamma-ray emission coincident with the positions of these new objects in six years of Fermi Large Area Telescope data. We found no significant excesses of gamma-ray emission. Under the assumption that the DES candidates are dSphs with DM halo properties similar to the known dSphs, we computed individual and combined limits on the velocity-averaged DM annihilation cross section for these new targets. If the estimated DM content of these dSph candidates is confirmed, they will constrain the annihilation cross section to lie below the thermal relic cross section for DM particles with masses ≲ 20 {GeV} annihilating via the b\bar{b} or tau+tau- channels.
234 citations
TL;DR: In this article, the properties of dense plasmas characteristic of the atmospheres of neutron stars and of the interior of massive white dwarfs are examined, and the problem of pressure ionization of hydrogen in a strong magnetic field and the crystallization of the quantum one-component plasma at finite temperature is discussed.
Abstract: We briefly examine the properties of dense plasmas characteristic of the atmospheres of neutron stars and of the interior of massive white dwarfs. These astrophysical bodies are natural laboratories for studying respectively the problem of pressure ionization of hydrogen in a strong magnetic field and the crystallization of the quantum one-component plasma at finite temperature.
233 citations
TL;DR: In this article, the rate at which close binaries consisting of a white dwarf and a main-sequence companion are formed by common envelope (CE) evolution is statistically studied and the distribution of properties like primary mass, secondary mass, and orbital period in post-CE binaries is studied.
Abstract: The rate at which close binaries consisting of a white dwarf and a main-sequence companion are formed by common envelope (CE) evolution is statistically studied The distribution of properties like primary mass, secondary mass, and orbital period in post-CE binaries is studied Results are presented for four cases bracketing reasonable choices of the initial mass ratio distribution and the fraction alpha of the gravitational binding energy between the secondary and the giant core which is available to eject the envelope The results indicate that interesting constraints on both these parameters can be derived from the observational data on double cores of PN 25 refs
232 citations
TL;DR: In this article, a new non-detection limit of the nearby SN Ia 2011fe, obtained what appears to be just 4 hours after the explosion, was presented, allowing us to directly constrain the initial primary radius, R_p Coupled with the nondetection of a quiescent X-ray counterpart and the inferred synthesized Ni mass, we show that R_ p 10,000 gm cm^{-3}, and that the effective temperature must be less than a few x 10^5 K.
Abstract: While a white dwarf is, from a theoretical perspective, the most plausible primary star in Type Ia supernova (SN Ia), many other candidates have not been formally ruled out Shock energy deposited in the envelope of any exploding primary contributes to the early SN brightness and, since this radiation energy is degraded by expansion after the explosion, the diffusive luminosity depends on the initial primary radius We present a new non-detection limit of the nearby SN Ia 2011fe, obtained what appears to be just 4 hours after explosion, allowing us to directly constrain the initial primary radius, R_p Coupled with the non-detection of a quiescent X-ray counterpart and the inferred synthesized Ni mass, we show that R_p 10,000 gm cm^{-3}, and that the effective temperature must be less than a few x 10^5 K This rules out hydrogen burning main sequence stars and giants Constructing the helium-burning main sequence and carbon-burning main sequence, we find such objects are also excluded By process of elimination, we find that only degeneracy-supported compact objects---WDs and neutron stars---are viable as the primary star of SN 2011fe With few caveats, we also restrict the companion (secondary) star radius to R_ c <~ 01 R_sun, excluding Roche-Lobe overflowing red giant and main-sequence companions to high significance
232 citations
Carnegie Institution for Science1, California Institute of Technology2, Weizmann Institute of Science3, University of California, Berkeley4, Lawrence Berkeley National Laboratory5, University of Oxford6, Kavli Institute for Theoretical Physics7, University of California, Santa Barbara8, Harvard University9, National Radio Astronomy Observatory10, Las Cumbres Observatory Global Telescope Network11, University of Toronto12, San Diego State University13, Tel Aviv University14, University of Tokyo15
TL;DR: Perets et al. as discussed by the authors identified three peculiar transients with five distinguishing characteristics: peak luminosity in the gap between novae and supernovae (M_R ≈ - 15.5 to -16.5), rapid photometric evolution (t_(rise) ≈12-15 days), large photospheric velocities (≈6000 to 11,000 km s^(-1)), early spectroscopic evolution into nebular phase (1 to 3 months) and peculiar nebular spectra dominated by Calcium.
Abstract: From the first two seasons of the Palomar Transient Factory, we identify three peculiar transients (PTF09dav, PTF10iuv, PTF11bij) with five distinguishing characteristics: peak luminosity in the gap between novae and supernovae (M_R ≈ - 15.5 to -16.5), rapid photometric evolution (t_(rise) ≈12-15 days), large photospheric velocities (≈6000 to 11000 km s^(-1)), early spectroscopic evolution into nebular phase (≈1 to 3 months) and peculiar nebular spectra dominated by Calcium. We also culled the extensive decade-long Lick Observatory Supernova Search database and identified an additional member of this group, SN 2007ke. Our choice of photometric and spectroscopic properties was motivated by SN 2005E (Perets et al. 2010). To our surprise, as in the case of SN 2005E, all four members of this group are also clearly offset from the bulk of their host galaxy. Given the well-sampled early and late-time light curves, we derive ejecta masses in the range of 0.4--0.7 M_⊙. Spectroscopically, we find that there may be a diversity in the photospheric phase, but the commonality is in the unusual nebular spectra. Our extensive follow-up observations rule out standard thermonuclear and standard core-collapse explosions for this class of "Calcium-rich gap" transients. If the progenitor is a white dwarf, we are likely seeing a detonation of the white dwarf core and perhaps, even shock-front interaction with a previously ejected nova shell. In the less likely scenario of a massive star progenitor, a very non-standard channel specific to a low-metallicity environment needs to be invoked (e.g., ejecta fallback leading to black hole formation). Detection (or lack thereof) of a faint underlying host (dwarf galaxy, cluster) will provide a crucial and decisive diagnostic to choose between these alternatives.
231 citations