Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session M13: Supernovae, Gamma-Ray Bursts and Other Transients |
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Sponsoring Units: DAP Chair: Janna Levin, Barnard College of Columbia University Room: 250F |
Sunday, April 17, 2016 3:30PM - 3:42PM |
M13.00001: On the nature of short and long gamma-ray bursts Remo Ruffini, Chris Fryer, Marco Muccino, Jorge Rueda Hernandez For a long GRB (L-GRB) the induced gravitational collapse (IGC) paradigm proposes as progenitor a binary system made up of a carbon-oxygen core undergoing a supernova (SN) that triggers hypercritical accretion onto a neutron star (NS) companion. For a short GRB (S-GRB), a NS-NS merger is adopted. We divide L-GRBs and S-GRBs into subclasses, depending whether or not a black hole (BH) is formed. For long bursts, when no BH is formed we have the X-ray flashes (XRFs), with isotropic energy $E_{iso}\leq 10^{52}$ erg and rest-frame spectral peak energy $E_{p,i}\leq 200$ keV. When a BH is formed we have authentic L-GRBs, with $E_{iso}>10^{52}$ erg and $E_{p,i}>200$ keV. For short bursts, when no BH is formed we have short gamma-ray flashes (S-GRFs) with $E_{iso}\leq 10^{52}$ erg and $E_{p,i}\leq 2$ MeV, while an authentic S-GRBs occur if BH is formed, with $E_{iso}>10^{52}$ erg and $E_{p,i}>2$ MeV. We give examples and observational signatures of the four subclasses. In the case of S-GRBs and BdHNe evidence is given of the coincidence of the onset of the high-energy GeV emission with the birth of a Kerr-Newman BH. References: - R. Ruffini, 2015, Astron. Rep. 59, 591 - R. Ruffini, et al., 2015, ApJ 808, 190 - R. Ruffini, et al., 2015, ApJ 798, 10 [Preview Abstract] |
Sunday, April 17, 2016 3:42PM - 3:54PM |
M13.00002: Stochasticity and efficiency of convection-dominated vs. SASI-dominated supernova explosions Christian Cardall, Reuben Budiardja We present an initial report on 160 simulations of a highly simplified model of the post-bounce core-collapse supernova environment in three spatial dimensions (3D). We set different values of a parameter characterizing the impact of nuclear dissociation at the stalled shock in order to regulate the post-shock fluid velocity, thereby determining the relative importance of convection and the stationary accretion shock instability (SASI). While our convection-dominated runs comport with the paradigmatic notion of a `critical neutrino luminosity' for explosion at a given mass accretion rate (albeit with a nontrivial spread in explosion times just above threshold), the outcomes of our SASI-dominated runs are much more stochastic: a sharp threshold critical luminosity is `smeared out' into a rising probability of explosion over a $\sim 20\%$ range of luminosity. We also find that the SASI-dominated models are able to explode with 3 to 4 times less efficient neutrino heating, indicating that progenitor properties, and fluid and neutrino microphysics, conducive to the SASI would make the neutrino-driven explosion mechanism more robust. [Preview Abstract] |
Sunday, April 17, 2016 3:54PM - 4:06PM |
M13.00003: Binary Neutron Star Mergers: Prospects for Multimessenger Observations David Neilsen, Matthew Anderson, Luis Lehner, Steven Liebling, Carlos Palenzuela Binary neutron star mergers are possible progenitors for short gamma-ray bursts. We evolve a binary system of two neutron stars using the fully relativistic Einstein equations from an initial quasi-circular orbit, through and past merger. We consider different finite-temperature, nuclear equations of state, which vary from soft to quite stiff, and allow for magnetization of the system and neutrino cooling via a leakage scheme. We focus on potential observables, other than gravitational waves, produced mainly by the hot, strongly magnetized matter resulting from the merger. [Preview Abstract] |
Sunday, April 17, 2016 4:06PM - 4:18PM |
M13.00004: GCN capabilities and status, and the incorporation of LIGO/Virgo Scott Barthelmy The Gamma-ray Coordinates Network / Transient Astronomy Network (GCN/TAN) is a single-point source for all transient astronomy notification. It collects the astrophysical transients from the missions (space-based and nearly all ground-based), puts them into a standard format, and distributes them to whomever wants to receive them. This is all done autonomously (completely autonomous within GCN/TAN, and almost always autonomously within the producer end of operations). This automation means minimal time delays (<0.1 sec within GCN for VOEvent and binary socket-based distribution methods, and typically a few sec for email-based which is dependent on the internet email protocol and the number of hops, both of which are out of the control of GCN/TAN). The LIGO-VIRGO Collaboration (LVC) Notices are now implemented in the GCN/TAN system. During the proprietary phase, the recipients must have an MoU with LVC and LVC must authorize GCN to distribute LVC Notices to each given MoU follow-up observer. In addition to Notices, there are the GCN Circulars, which are prose-style reports of follow-up observations made and results obtains. During the LVC Proprietary phase there are also the GCN LVC Circulars, which also require authorization from LVC to join the LVC Circulars. [Preview Abstract] |
Sunday, April 17, 2016 4:18PM - 4:30PM |
M13.00005: Transients with the Fermi GBM Michelle Hui The Fermi Gamma-ray Burst Monitor (GBM) is an all-sky monitoring instrument sensitive to energies from 8 keV to 40 MeV. Its primary science objective is observing gamma-ray bursts (GRBs) in support of the Large Area Telescope, which are both part of the Fermi Gamma-ray Space Telescope. Over the past 7 years of operation, the GBM has detected over 240 GRBs per year and provided timely GCN notices for follow-up observations. In addition to GRBs, Galactic transients, solar flares, and terrestrial gamma-ray flashes have also been observed. With several instruments coming online recently, such as the gravitational wave detectors Advanced LIGO/Virgo and the very high energy surveying instrument HAWC, now is an opportune time for multi-messenger collaboration in counterpart search of gravitational waves and GRBs. [Preview Abstract] |
Sunday, April 17, 2016 4:30PM - 4:42PM |
M13.00006: Multidimensional Simulations of Magnetar Powered Supernovae Ke-Jung Chen Magnetars are neutron stars with unusually strong magnetic fields, typically greater than 1E13 Gauss (G). Observational evidence suggests that magnetars form in a significant fraction of supernovae. Previous studies have shown that the radiation emitted by a rapidly rotating magnetar embedded in a young supernova can greatly amplify its luminosity. These one-dimensional studies also shown the existence of an instability arising from the piling up of radiatively accelerated matter in a dense, thin shell deep inside the supernova. Here, we examine the problem in two dimensions and find that this shell fragments into a filamenary structure that facilitates mixing. The degree of the mixing depends on the relative energy input by the magnetar and the kinetic energy of the inner ejecta. The light curve and spectrum of the resulting supernova will be appreciably altered. [Preview Abstract] |
Sunday, April 17, 2016 4:42PM - 4:54PM |
M13.00007: Search for Kilonovae in Dark Energy Survey Supernova Fields Zoheyr Doctor The Dark Energy Camera on the Blanco 4-m Telescope is an ideal instrument for identifying rapid optical transients with its large field of view and four optical filters. We utilize two seasons of data from the Dark Energy Survey to search for kilonovae, an optical counterpart to gravitational waves from binary neutron star mergers. Kilonova lightcurves from Barnes and Kasen inform our analysis for removing background signals such as supernovae. We simulate DES observations of kilonovae with the SNANA software package to estimate our search efficiency and optimize cuts. Finally, we report rate limits for binary neutron star mergers and compare to existing rate estimates. [Preview Abstract] |
Sunday, April 17, 2016 4:54PM - 5:06PM |
M13.00008: Ring of nine Gamma Ray Burst overlap with the hot spot of my hypothesis Dayong Cao During 2004 to 2014, a symmetry axis and a cold spot (a structure of one billion light years across) of CMB were observed, and I supposed there is a hot spot, and there is a symmetry between the cold spot and the hot spot of CMB. \underline {http://www.dailymail.co.uk/sciencetech/article-2430415 } \underline {http://meetings.aps.org/link/BAPS.2014.MAR.Y33.9} In 2015, a Ring of Nine Gamma Ray Burst (a structure of FIVE BILLION light years across) which is a part of structure of double helix and overlap with the hot spot was observed. \underline {http://www.dailymail.co.uk/sciencetech/article-3185193} The Ring of Nine Gamma Ray Burst could be explained by the hot spot. There is a balance systemic model with structure of double helix of the flat universe between cold spot and hot spot-a balance between stellar matter and dark massenergy (include dark matter and dark energy). The model can explain of the Hubble's redshift. There is a larger dark hole instead of the huge black hole of the center of the Milky Way galaxy, and a dark hole builds up a balance system with sun. This model should explain of the seasonal Extinctions. \underline {http://meetings.aps.org/link/BAPS.2015.APR.H14.8} [Preview Abstract] |
Sunday, April 17, 2016 5:06PM - 5:18PM |
M13.00009: Detection of pair plasma in recent V404 Cygni flares Roland Diehl, Thomas Siegert, Jochen Greiner, Martin Krause, Andrei Beloborodov, Marion Cadolle Bel, Fabrizia Guglielmetti, Jerome Rodriguez, Andrew Strong, Xiaoling Zhangh The release of gravitational energy from the accretion of matter onto a black hole still is a mystery. Observationally, the thermal radiadion from an inner accretion disk and its high energy tail are manifestations of processes in the inner region, while the ejection of radio jets demonstrates the energy and plasma outflow on larger scales. Models include materialisation of energy from the central source in the form of pair creation within a region of high density that is opaque to all kinds of radiation. At some point leptons may escape the dense inner regions, and annihilation of positrons in nearby components such as the corona and accretion disk could be expected. Transient line features have been reported from two sources before, and tentatively associated with positron annihilation. Flaring of the microquasar V404 Cygni in June-July 2015 allowed to test this model again. With SPI on INTEGRAL, which has demonstrated excellent measurement capability for positron annihilation in the Galaxy, we now find characteristic signatures of the annihilation of positrons across the 200-1000 keV energy range during this flaring phase. We discuss details of the positron annihilation spectra, and what they might tell us about pair plasma in the central energy source of microquasars. [Preview Abstract] |
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