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Colliding with a crunching bubble

Description: In the context of eternal inflation we discuss the fate of Lambda = 0 bubbles when they collide with Lambda< 0 crunching bubbles. When the Lambda = 0 bubble is supersymmetric, it is not completely destroyed by collisions. If the domain wall separating the bubbles has higher tension than the BPS bound, it is expelled from the Lambda = 0 bubble and does not alter its long time behavior. If the domain wall saturates the BPS bound, then it stays inside the Lambda = 0 bubble and removes a finite fraction of future infinity. In this case, the crunch singularity is hidden behind the horizon of a stable hyperbolic black hole.
Date: March 26, 2007
Creator: Freivogel, Ben; Freivogel, Ben; Horowitz, Gary T. & Shenker, Stephen
Partner: UNT Libraries Government Documents Department

Horizons and plane waves: A review

Description: We review the attempts to construct black hole/string solutions in asymptotically plane wave spacetimes. First, we demonstrate that geometries admitting a covariantly constant null Killing vector cannot admit event horizons, which implies that pp-waves can't describe black holes. However, relaxing the symmetry requirements allows us to generate solutions which do possess regular event horizons while retaining the requisite asymptotic properties. In particular, we present two solution generating techniques and use them to construct asymptotically plane wave black string/brane geometries.
Date: November 6, 2003
Creator: Hubeny, Veronika E. & Rangamani, Mukund
Partner: UNT Libraries Government Documents Department

Geometry of non-supersymmetric three-charge bound states

Description: We study the smooth non-supersymmetric three-charge microstatesof Jejjala, Madden, Ross and Titchener using Kaluza-Klein reductions of the solutions to five and four dimensions. Our aim is to improve our understanding of the relation between these non-supersymmetric solutions and the well-studied supersymmetric cases. We find some surprising qualitative differences. In the five-dimensional description, the solution has orbifold fixed points which break supersymmetry locally, so the geometries cannot be thought of as made up of separate half-BPS centers. In the four-dimensional description, the two singularities in the geometry are connected by a conical singularity, which makes it impossible to treat them independently and assign unambiguous brane charges to these centers.
Date: May 14, 2007
Creator: Gimon, Eric G.; Levi, Thomas S. & Ross, Simon F.
Partner: UNT Libraries Government Documents Department

Variability-Selected Low-Luminosity Active Galactic Nuclei in the 4 Ms Chandra Deep Field-South

Description: This article demonstrates that the observed variability cannot be explained by X-ray Binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole.
Date: January 18, 2012
Creator: Young, Monica; Brandt, William Nielsen; Xue, Yongquan; Alexander, David M.; Bauer, Franz E.; Lehmer, Bret et al.
Partner: UNT College of Arts and Sciences

Harmonic resolution as a holographic quantum number

Description: The Bekenstein bound takes the holographic principle into the realm of flat space, promising new insights on the relation of non-gravitational physics to quantum gravity. This makes it important to obtain a precise formulation of the bound. Conventionally, one specifies two macroscopic quantities, mass and spatial width, which cannot be simultaneously diagonalized. Thus, the counting of compatible states is not sharply defined. The resolution of this and other formal difficulties leads naturally to a definition in terms of discretized light-cone quantization. In this form, the area difference specified in the covariant bound converts to a single quantum number, the harmonic resolution K. The Bekenstein bound then states that the Fock space sector with K units of longitudinal momentum contains no more than exp(2 pi^2 K) independent discrete states. This conjecture can be tested unambiguously for a given Lagrangian, and it appears to hold true for realistic field theories, including models arising from string compactifications. For large K, it makes contact with more conventional but less well-defined formulations.
Date: January 31, 2004
Creator: Bousso, Raphael
Partner: UNT Libraries Government Documents Department

Black holes in supergravity: the non-BPS branch

Description: We construct extremal, spherically symmetric black hole solutions to 4D supergravity with charge assignments that preclude BPS-saturation. In particular, we determine the ground state energy as a function of charges and moduli. We find that the mass of the non-BPS black hole remains that of a marginal bound state of four basic constituents throughout the entire moduli space and that there is always a non-zero gap above the BPS bound.
Date: October 25, 2007
Creator: Gimon, Eric; Gimon, Eric G.; Larsen, Finn & Simon, Joan
Partner: UNT Libraries Government Documents Department

Duality, Entropy and ADM Mass in Supergravity

Description: We consider the Bekenstein-Hawking entropy-area formula in four dimensional extended ungauged supergravity and its electric-magnetic duality property. Symmetries of both"large" and"small" extremal black holes are considered, as well as the ADM mass formula for N=4 and N=8 supergravity, preserving different fraction of supersymmetry. The interplay between BPS conditions and duality properties is an important aspect of this investigation.
Date: February 23, 2009
Creator: Cerchiai, Bianca L.; Ferrara, Sergio; Marrani, Alessio & Zumino, Bruno
Partner: UNT Libraries Government Documents Department

Black Hole Growth Is Mainly Linked to Host-galaxy Stellar Mass Rather Than Star Formation Rate

Description: This article investigates the dependence of black hole accretion rate (BHAR) on host-galaxy star formation rate (SFR) and stellar mass in the CANDELS/GOODS-South field in the redshift range of 0.5 ⩽ z < 2.0.
Date: June 15, 2017
Creator: Yang, G.; Chen, C. -T. J.; Vito, F.; Brandt, William Nielsen; Alexander, David M.; Luo, Bin et al.
Partner: UNT College of Arts and Sciences

Reverberation Mapping of High-Luminosity Quasars

Description: This article presents the CIV BLR size and luminosity relation over eight orders of magnitude in luminosity, pushing the luminosity limit to its highest point so far.
Date: August 31, 2017
Creator: Kaspi, Shai; Brandt, William Nielsen; Maoz, Dan; Netzer, Hagai; Schneider, Donald P. & Shemmer, Ohad
Partner: UNT College of Arts and Sciences

On The Performance of Quasar Reverberation Mapping in the Era of Time-Domain Photometric Surveys

Description: This article quantitatively assesses, by means of comprehensive numerical simulations, the ability of broadband photometric surveys to recover the broad emission line region size in quasars under various observing conditions and for a wide range of object properties.
Date: February 2, 2014
Creator: Chelouche, Doron; Shemmer, Ohad; Cotlier, Gabriel I.; Barth, Aaron J. & Rafter, Stephen E.
Partner: UNT College of Arts and Sciences

Black ring deconstruction

Description: We present a sample microstate for a black ring in four and five dimensional language. The microstate consists of a black string microstate with an additional D6-brane. We show that with an appropriate choice of parameters the piece involving the black string microstate falls down a long AdS throat, whose M-theory lift is AdS_3 x S2. We wrap a spinning dipole M2-brane on the S2 in the probe approximation. In IIA, this corresponds to a dielectric D2-brane carrying only D0-charge. We conjecture this is the firstapproximation to a cloud of D0-branes blowing up due to their non-abelian degrees of freedom and the Myers effect.
Date: June 22, 2007
Creator: Gimon, Eric; Gimon, Eric G. & Levi, Thomas S.
Partner: UNT Libraries Government Documents Department

A Search for Microsecond Gamma Ray Bursts From Primordial Black Holes

Description: The project is called SGARFACE (Short Gamma Ray Front Air Cherenkov Experiment) and is an atmospheric Cherenkov detector to provide sensitivity to short bursts of gamma rays of extraterrestrial origin. The detector is an addition to the Whipple 10m gamma ray telescope on Mt. Hopkins in southern Arizona and uses a digital trigger module for recognizing Cherenkov light flashes from gamma ray bursts. The digital trigger modules have been designed, tested and constructed at Iowa State University and have been installed at the Whipple 10m telescope. Operation of the experiment started in March 2003 and data collecting will likely continue until spring of 2005. A final results paper addressing a search for primordial black holes is likely to be finished by summer of 2005.
Date: August 12, 2004
Creator: Krennrich, Frank
Partner: UNT Libraries Government Documents Department

Entropy of near-extremal black holes in AdS5

Description: We construct the microstates of near-extremal black holes in AdS_5 x S5 as gases of defects distributed in heavy BPS operators in the dual SU(N) Yang-Mills theory. These defects describe open strings on spherical D3-branes in the S5, and we show that they dominate the entropy by directly enumerating them and comparing the results with a partition sum calculation. We display new decoupling limits in which the field theory of the lightest open strings on the D-branes becomes dual to a near-horizon region of the black hole geometry. In the single-charge black hole we find evidence for an infrared duality between SU(N) Yang-Mills theories that exchanges the rank of the gauge group with an R-charge. In the two-charge case (where pairs of branes intersect on a line), the decoupled geometry includes an AdS_3 factor with a two-dimensional CFT dual. The degeneracy in this CFT accounts for the black hole entropy. In the three-charge case (where triples of branes intersect at a point), the decoupled geometry contains an AdS_2 factor. Below a certain critical mass, the two-charge system displays solutions with naked timelike singularities even though they do not violate a BPS bound. We suggest a string theoretic resolution of these singularities.
Date: July 24, 2007
Creator: Simon, Joan; Balasubramanian, Vijay; de Boer, Jan; Jejjala, Vishnu & Simon, Joan
Partner: UNT Libraries Government Documents Department

Experimental plasma astrophysics using a T{sup 3} (Table-top Terawatt) laser

Description: Lasers that can deliver immense power of Terawatt (10{sup 12}W) and can still compactly sit on a Table-Top (T{sup 3} lasers) emerged in the 1990s. The advent of these lasers allows us to access to regimes of astronomical physical conditions that once thought impossible to realize in a terrestrial laboratory. We touch on examples that include superhigh pressure materials that may resemble the interior of giant planets and white dwarfs and of relativistic temperature plasmas that may exist in the early cosmological epoch and in the neighborhood of the blackhole event horizon.
Date: November 1, 1996
Creator: Tajima, T.
Partner: UNT Libraries Government Documents Department

Accretion onto black holes: The power generating mechanism

Description: This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The physical relationships among accretion disks, quasars, black holes, collimated radio sources and galactic dynamos previously has been only weakly related without explicit cause and effect. We have constructed a physical evolution from large, primordial density perturbations to {open_quotes}damped Lyman alpha clouds,{close_quotes} to galaxy formation, to black holes, jets, and the the galactic dynamo. We have derived the general relativistic distortions of radiation emitted from close to the black hole and thereby have a new observational test of the central engine. The physics of accretion disks, the astrophysical dynamo, and magnetic reconnection are the least understood physical phenomena in astrophysics. They are still less understood in the general relativity (GR) field close to the black hole. This lack of physical understanding frustrates a quantitative evaluation of observations that define the evolution from the early universe to star formation. We have made progress in this understanding.
Date: December 31, 1998
Creator: Colgate, S.A.; Hills, J.G. & Miller, W.A.
Partner: UNT Libraries Government Documents Department


Description: We present results of observations of several X-ray transients with RXTE in 1996-1998, namely, GRS 1739-278, XTE J1748-288, GS 1354-64, 2S1803-245 and XTE J0421+560 (CI Cam). We studied light curves and spectra of their outbursts and compared them with observations of other X-ray transients. We discuss fits of high state spectra with BMC model, and similarities and differences between black holes and neutron stars in their low state. Special attention is paid to CI Cam as possible legate for new class of X-ray transients.
Date: November 1, 1999
Partner: UNT Libraries Government Documents Department

Tracing the accretion history of supermassive black holes through X-ray variability: results from the Chandra Deep Field-South

Description: This article studies the X-ray variability properties of distant active galactic nuclei (AGNs) in the Chandra Deep Field-South region over 17 yr, up to z ~ 4, and compare them with those predicted by models based on local samples.
Date: July 14, 2017
Creator: Paolillo, Maurizio; Papadakis, I.; Brandt, William Nielsen; Luo, Bin; Xue, Yongquan; Tozzi, Paolo et al.
Partner: UNT College of Arts and Sciences

Fast-Growing SMBHs in Fast-Growing Galaxies, at High Redshifts: The Role of Major Mergers as Revealed by ALMA

Description: This article presents a long-term, multi-wavelength project to understand the epoch of fastest growth of the most massive black holes by using a sample of 40 luminous quasars at z ≃ 4.8.
Date: September 30, 2017
Creator: Trakhtenbrot, Benny; Lira, Paulina; Netzer, Hagai; Cicone, Claudia; Maiolino, Roberto & Shemmer, Ohad
Partner: UNT College of Arts and Sciences

Understanding the physics of a possible non-Abelian fractional quantum hall effect state.

Description: We wish to present in this report experimental results from a one-year Senior Council Tier-1 LDRD project that focused on understanding the physics of a possible non-Abelian fractional quantum Hall effect state. We first give a general introduction to the quantum Hall effect, and then present the experimental results on the edge-state transport in a special fractional quantum Hall effect state at Landau level filling {nu} = 5/2 - a possible non-Abelian quantum Hall state. This state has been at the center of current basic research due to its potential applications in fault-resistant topological quantum computation. We will also describe the semiconductor 'Hall-bar' devices we used in this project. Electron physics in low dimensional systems has been one of the most exciting fields in condensed matter physics for many years. This is especially true of quantum Hall effect (QHE) physics, which has seen its intellectual wealth applied in and has influenced many seemingly unrelated fields, such as the black hole physics, where a fractional QHE-like phase has been identified. Two Nobel prizes have been awarded for discoveries of quantum Hall effects: in 1985 to von Klitzing for the discovery of integer QHE, and in 1998 to Tsui, Stormer, and Laughlin for the discovery of fractional QHE. Today, QH physics remains one of the most vibrant research fields, and many unexpected novel quantum states continue to be discovered and to surprise us, such as utilizing an exotic, non-Abelian FQHE state at {nu} = 5/2 for fault resistant topological computation. Below we give a briefly introduction of the quantum Hall physics.
Date: October 1, 2010
Creator: Pan, Wei; Crawford, Matthew; Tallakulam, Madhu & Ross, Anthony Joseph, III
Partner: UNT Libraries Government Documents Department

Towards laboratory-produced relativistic electron-positron pair-plasmas

Description: Relativistic pair-plasmas and jets are believed to exist in many astrophysical objects and are often invoked to explain energetic phenomena related to Gamma Ray Bursts and Black Holes. On earth, positrons from radioactive isotopes or accelerators are used extensively at low energies (sub-MeV) in areas related to surface science positron emission tomography and basic antimatter science. Experimental platforms capable of producing the high-temperature pair-plasma and high-flux jets required to simulate astrophysical positron conditions have so far been absent. In the last few years, we performed extensive experiments generating positrons with intense lasers where we found that relativistic electron and positron jets are produced by irradiating a solid gold target with an intense picosecond laser pulse. The positron temperatures in directions parallel and transverse to the beam both exceeded 0.5 MeV, and the density of electrons and positrons in these jets are of order 10{sup 16} cm{sup -3} and 10{sup 13} cm{sup -3}, respectively. With the advent of high-energy ultra-short laser pulses, we expect that a charge-neutral, relativistic pair-plasma is achievable, a novel regime of laboratory-produced hot dense matter. This talk will present some details of the laser-produced pair-plasma experiments.
Date: August 31, 2010
Creator: Chen, H; Wilks, S C; Meyerhofer, D D; Beiersdorfer, P; Cauble, R; Dollar, F et al.
Partner: UNT Libraries Government Documents Department

Optical, UV, and EUV Oscillations of SS Cygni in Outburst

Description: I provide a review of observations in the optical, UV (HST), and EUV (EUVE and Chandra LETG) of the rapid periodic oscillations of nonmagnetic, disk-accreting, high mass-accretion rate cataclysmic variables (CVs), with particular emphasis on the dwarf nova SS Cyg in outburst. In addition, I drawn attention to a correlation, valid over nearly six orders of magnitude in frequency, between the frequencies of the quasi-periodic oscillations (QPOs) of white dwarf, neutron star, and black hole binaries. This correlation identifies the high frequency quasi-coherent oscillations (so-called ''dwarf nova oscillations'') of CVs with the kilohertz QPOs of low mass X-ray binaries (LMXBs), and the low frequency and low coherence QPOs of CVs with the horizontal branch oscillations (or the broad noise component identified as such) of LMXBs. Assuming that the same mechanisms produce the QPOs of white dwarf, neutron star, and black hole binaries, this correlation has important implications for QPO models.
Date: December 19, 2003
Creator: Mauche, C W
Partner: UNT Libraries Government Documents Department

Gravitational Lensing of Supernova Neutrinos

Description: The black hole at the center of the galaxy is a powerful lens for supernova neutrinos. In the very special circumstance of a supernova near the extended line of sight from Earth to the galactic center, lensing could dramatically enhance the neutrino flux at Earth and stretch the neutrino pulse.
Date: October 1, 2006
Creator: Mena, Olga; U., /Fermilab /Rome; Mocioiu, Irina; U., /Penn State; Quigg, Chris & /Fermilab
Partner: UNT Libraries Government Documents Department