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Evidence for a Link Between Fe K-alpha Emission Line Strength and QPO Phase in a Black HoleJan 18 2005In X-ray binaries, the frequencies revealed in X-ray quasi-periodic oscillations (QPOs) are often interpreted as characteristic frequencies in the inner accretion disk, though the exact oscillation mechanism is unknown at present. Broadened Fe K-alpha ... More

Fragmentation dynamics of DNA sequence duplicationsApr 04 2013Oct 29 2013Motivated by empirical observations of algebraic duplicated sequence length distributions in a broad range of natural genomes, we analytically formulate and solve a class of simple discrete duplication/substitution models that generate steady-states sharing ... More

X-ray and Radio Constraints on the Mass of the Black Hole in Swift J164449.3+573451Jun 13 2011Jul 28 2011Swift J164449.3+573451 is an exciting transient event, likely powered by the tidal disruption of a star by a massive black hole. The distance to the source, its transient nature, and high internal column density serve to complicate several means of estimating ... More

The Angular Momenta of Neutron Stars and Black Holes as a Window on SupernovaeFeb 08 2011It is now clear that a subset of supernovae display evidence for jets and are observed as gamma-ray bursts. The angular momentum distribution of massive stellar endpoints provides a rare means of constraining the nature of the central engine in core-collapse ... More

A Comparison of Intermediate Mass Black Hole Candidate ULXs and Stellar-Mass Black HolesJun 29 2004Jun 30 2004Cool thermal emission components have recently been revealed in the X-ray spectra of a small number of ultra-luminous X-ray (ULX) sources with L_X > 1 E+40 erg/s in nearby galaxies. These components can be well fitted with accretion disk models, with ... More

Revealing a Cool Accretion Disk in the Ultraluminous X-ray Source M81 X-9 (Holmberg IX X-1): Evidence for an Intermediate Mass Black HoleOct 21 2003Mar 18 2004We report the results of an analysis of two XMM-Newton/EPIC-pn spectra of the bright ultraluminous X-ray source M81 X-9 (Holmberg IX X-1), obtained in snapshot observations. Soft thermal emission is clearly revealed in spectra dominated by hard power-law ... More

On the Robustness of Cool Disc Components in Bright ULXsDec 22 2005In this letter, we comment on the robustness of putative cool (kT ~ 0.2 keV) accretion disc components in the X-ray spectra of the most luminous (L ~ 10^40 erg/s) ultra-luminous X-ray sources (ULXs) in nearby normal galaxies. When compared to stellar-mass ... More

Sub-parsec supermassive Binary Quasars: expectations at z<1Mar 23 2009Aug 21 2009We investigate the theoretical expectations for detections of supermassive binary black holes that can be identified as sub-parsec luminous quasars. To-date, only two candidates have been selected in a sample comprising 17,500 sources selected from the ... More

A Prominent Accretion Disk in the Low-Hard State of the Black Hole Candidate SWIFT J1753.5-0127May 08 2006Aug 25 2006We report on simultaneous XMM-Newton and RXTE observations of the stellar-mass black hole candidate SWIFT J1753.5-0127. The source was observed in the low-hard state, during the decline of a hard outburst. The inner accretion disk is commonly assumed ... More

Observational Evidence for Intermediate-Mass Black Holes in Ultra-luminous X-ray SourcesFeb 27 2004Evidence is mounting that some Ultra-luminous X-ray sources (ULXs) may contain accreting intermediate-mass black holes (IMBHs). We review the current observational evidence for IMBH-ULXs. While low-luminosity ULXs with L_X <~ 10^39.5 erg/s (assuming isotropic ... More

Intermediate-Mass Black HolesAug 22 2003Feb 23 2004The mathematical simplicity of black holes, combined with their links to some of the most energetic events in the universe, means that black holes are key objects for fundamental physics and astrophysics. Until recently, it was generally believed that ... More

X-ray Signatures of Circumnuclear Gas in AGNNov 01 2011X-ray spectra of AGN are complex. X-ray absorption and emission features trace gas covering a wide range of column densities and ionization states. High resolution spectra show the absorbing gas to be outflowing, perhaps in the form of an accretion disk ... More

The Tsallis ParameterJan 31 2013The exact solution of a particular form of the stationary state generalized Fokker-Planck equations, which is given under certain conditions by the classical Tsallis distribution, is compared with the solution of the MAXENT equations obtained using the ... More

A direct measurement of the heat release in the outer crust of the transiently accreting neutron star XTE J1709-267Dec 06 2012Apr 02 2013The heating and cooling of transiently accreting neutron stars provides a powerful probe of the structure and composition of their crust. Observations of superbursts and crust cooling of accretion-heated neutron stars require more heat release than is ... More

MAXENT and the Tsallis ParameterAug 07 2014The nonextensive entropic measure proposed by Tsallis introduces a parameter, q, which is not defined but rather must be determined. The value of q is typically determined from a piece of data and then fixed over the range of interest. On the other hand, ... More

Interactions of massless monopole cloudsJan 26 2009Aug 23 2009Some spontaneously broken gauge theories with unbroken non-Abelian gauge groups contain massless magnetic monopoles that are realized classically as clouds of non-Abelian field surrounding one or more massive monopoles. We use moduli space methods to ... More

The quiescent counterpart of the peculiar X-ray burster SAX J2224.9+5421Apr 14 2014SAX J2224.9+5421 is an extraordinary neutron star low-mass X-ray binary. Albeit discovered when it exhibited a ~10-s long thermonuclear X-ray burst, it had faded to a 0.5-10 keV luminosity of Lx<8E32 (D/7.1 kpc)^2 erg/s only ~8 hr later. It is generally ... More

Effective equidistribution and the Sato-Tate law for families of elliptic curvesApr 16 2010Apr 30 2010Extending recent work of others, we provide effective bounds on the family of all elliptic curves and one-parameter families of elliptic curves modulo p (for p prime tending to infinity) obeying the Sato-Tate Law. We present two methods of proof. Both ... More

The vanishing limit of the square-well fluid: the adhesive hard sphere model as a reference systemDec 18 2007We report a simulation study of the gas-liquid critical point for the square-well potential, for values of well width delta as small as 0.005 times the particle diameter sigma. For small delta, the reduced second virial coefficient at the critical point ... More

On the size and location of the X-ray emitting coronae around black holesApr 17 2013The observation of energetic X-ray emission from black holes, inconsistent with thermal emission from an accretion disk, has long indicated the presence of a "corona" around these objects. However, our knowledge of the geometry, composition, and processes ... More

The Formation and Structure of a Strongly Magnetized Corona above Weakly Magnetized Accretion DisksDec 07 1999We use three-dimensional magnetohydrodynamical (MHD) simulations to study the formation of a corona above an initially weakly magnetized, isothermal accretion disk. We also describe a modification to time-explicit numerical algorithms for MHD which enables ... More

Line-of-Sight Anisotropies within X-ray Luminous Cluster SamplesJun 26 1999We present the results from two-point spatial correlation analyses on X-ray confirmed northern Abell clusters. The cluster samples are subsets of a volume-limited ROSAT All-Sky Survey study of 294 Abell clusters of which 240 are X-ray luminous. We examined ... More

Reapproaching the Spin Estimate of GX 339-4May 20 2015We systematically reanalyze two previous observations of the black hole (BH) GX 339-4 in the very high and intermediate state taken with $\emph{XMM-Newton}$ and $\emph{Suzaku}$. We utilize up-to-date data reduction procedures and implement the recently ... More

X-ray Spectroscopic Evidence for Intermediate Mass Black Holes: Cool Accretion Disks in Two Ultra--Luminous X-ray SourcesNov 08 2002Jan 17 2003We have analyzed an XMM-Newton observation of the nearby spiral galaxy NGC 1313, which contains two "ultra-luminous" X-ray (ULX) sources. We measure isotropic luminosities of L_X = 2.0 * 10^(40) erg/s and L_X = 6.6 * 10^(39) erg/s for NGC 1313 X-1 and ... More

One-Loop Tensor Integrals in Dimensional RegularisationDec 19 1996Jan 26 1998We show how to evaluate tensor one-loop integrals in momentum space avoiding the usual plague of Gram determinants. We do this by constructing combinations of $n$- and $(n-1)$-point scalar integrals that are finite in the limit of vanishing Gram determinant. ... More

A Unified View of Transport EquationsJun 15 2019Distribution functions of many static transport equations are found using the Maximum Entropy Principle. The equations of constraint which contain the relevant dynamical information are simply the low-lying moments of the distributions. Systems subject ... More

The One-loop QCD Corrections for gamma^* to q qbar ggJun 09 1997Sep 17 1998We compute the one-loop QCD amplitudes for the decay of an off-shell vector boson with vector couplings into a quark-antiquark pair accompanied by two gluons keeping, for the first time, all orders in the number of colours. Together with previous work ... More

Second order parameter-uniform convergence for a finite difference method for a singularly perturbed linear reaction-diffusion systemApr 05 2010A singularly perturbed linear system of second order ordinary differential equations of reaction-diffusion type with given boundary conditions is considered. The leading term of each equation is multiplied by a small positive parameter. These singular ... More

A parameter--uniform finite difference method for a singularly perturbed linear system of second order ordinary differential equations of reaction-diffusion typeJun 22 2009A singularly perturbed linear system of second order ordinary differential equations of reaction-diffusion type with given boundary conditions is considered. The leading term of each equation is multiplied by a small positive parameter. These parameters ... More

A comparison of the optical properties of radio-loud and radio-quiet quasarsOct 23 1998We have made radio observations of 87 optically selected quasars at 5 GHz with the VLA in order to measure the radio power for these objects and hence determine how the fraction of radio-loud quasars varies with redshift and optical luminosity. The sample ... More

Swift monitoring of Cygnus X-2: investigating the NUV-X-ray connectionSep 21 2009Jul 19 2010The neutron star X-ray binary (NSXRB) Cygnus X-2 was observed by the Swift satellite 51 times over a 4 month period in 2008 with the XRT, UVOT, and BAT instruments. During this campaign, we observed Cyg X-2 in all three branches of the Z track (horizontal, ... More

The Rayleigh QuotientDec 01 2011The central role of the Rayleigh quotient in many body physics is discussed. Various many body methods can be obtained from either an attempt to evaluate the Rayleigh Quotient directly or through various variational approximations. Rather than dwell on ... More

On Neutral Absorption and Spectral Evolution in X-ray BinariesOct 15 2009Current X-ray observatories make it possible to follow the evolution of transient and variable X-ray binaries across a broad range in luminosity and source behavior. In such studies, it can be unclear whether evolution in the low energy portion of the ... More

The high-energy emission from GX 339-4 as seen with INTEGRAL and XMM-NewtonDec 07 2008GX 339--4 is a well-known microquasar. In this contribution we show the obtained results with the INTEGRAL and XMM-Newton observatories of the outburst undertaken on 2007. The observations cover spectral evolution from the hard, soft intermediate states ... More

The high energy emission from black holesNov 06 2007The origin of the high energy emission (X-rays and gamma-rays) from black holes is still a matter of debate. We present new evidence that hard X-ray emission in the low/hard state may not be dominated by thermal Comptonization. We present an alternative ... More

From expanded digraphs to lifts of voltage digraphs and line digraphsAug 22 2016Oct 01 2016In this note we present a general approach to construct large digraphs from small ones. These are called expanded digraphs, and, as particular cases, we show the close relationship between lifted digraphs of voltage digraphs and line digraphs, which are ... More

Synthetic Spectral Analysis of the Hot Component in the S-Type Symbiotic Variable EG AndromedaJul 26 2004We have applied grids of NLTE high gravity model atmospheres and optically thick accretion disk models for the first time to archival IUE and FUSE spectra of the S-type symbiotic variable EG And taken at superior spectroscopic conjunction when Rayleigh ... More

Second order parameter-uniform convergence for a finite difference method for a singularly perturbed linear parabolic systemAug 14 2010A singularly perturbed linear system of second order partial differential equations of parabolic reaction-diffusion type with given initial and boundary conditions is considered. The leading term of each equation is multiplied by a small positive parameter. ... More

Three Dimensional Numerical General Relativistic Hydrodynamics I: Formulations, Methods, and Code TestsNov 04 1998This is the first in a series of papers on the construction and validation of a three-dimensional code for general relativistic hydrodynamics, and its application to general relativistic astrophysics. This paper studies the consistency and convergence ... More

X-ray reflection from the inner disk of the AGN Ton S180Oct 30 2017We analyse a long archival XMM-Newton observation of the narrow-line Seyfert 1 galaxy Ton S180, using the latest reflection models to explore the high quality X-ray spectrum. We find that the iron line is relatively narrow and sharp, and the soft excess ... More

CP Asymmetries in Higgs decays to ZZ at the LHCAug 27 2007We examine the effect of a general HZZ coupling through a study of the Higgs decay to leptons via Z bosons at the LHC. We discuss various methods for placing limits on additional couplings, including measurement of the partial width, threshold scans, ... More

Aspects of CP violation in the HZZ coupling at the LHCAug 03 2007Dec 14 2007We examine the CP-conserving (CPC) and CP-violating (CPV) effects of a general HZZ coupling through a study of the process H -> ZZ* -> 4 leptons at the LHC. We construct asymmetries that directly probe these couplings. Further, we present complete analytical ... More

The influence of spin on jet power in neutron star X-ray binariesApr 06 2011We investigate the role of the compact object in the production of jets from neutron star X-ray binaries. The goal is to quantify the effect of the neutron star spin, if any, in powering the jet. We compile all the available measures or estimates of the ... More

A Deep XMM-Newton Observation of the Quasar 3C 287Sep 26 2008We report on an XMM-Newton observation of the z=1.055 quasar and Giga-hertz Peaked Spectrum (GPS) source 3C 287. Our 62.3 ksec observation provides an exceptional X-ray view of a prominent member of this important subclass of active galactic nuclei (AGN). ... More

Interaction between superconductor and ferromagnetic domains in iron sheath: peak effect in MgB2/Fe wiresJul 22 2005Interaction between the superconductor and ferromagnet in MgB2/Fe wires results in either a plateau or a peak effect in the field dependence of transport critical current, Ic(H). This is in addition to magnetic shielding of external field. Current theoretical ... More

The Cosmological History of Accretion onto Supermassive Black HolesJun 24 2005Aug 09 2006It is argued that supermassive black holes in the nuclei of galaxies most likely have grown coevally with their host dark matter halos. A calculation based on Press-Schechter within this framework shows that the mean rate of accretion of matter onto such ... More

Double Higgs production at TeV Colliders in the Minimal Supersymmetric Standard ModelFeb 23 2000Mar 27 2000The reconstruction of the Higgs potential in the Minimal Supersymmetric Standard Model (MSSM) requires the measurement of the trilinear Higgs self-couplings. The `double Higgs production' subgroup has been investigating the possibility of detecting signatures ... More

Nondegenerate 3D complex Euclidean superintegrable systems and algebraic varietiesAug 22 2007A classical (or quantum) second order superintegrable system is an integrable n-dimensional Hamiltonian system with potential that admits 2n-1 functionally independent second order constants of the motion polynomial in the momenta, the maximum possible. ... More

Superintegrability in a non-conformally-flat spaceNov 07 2012Superintegrable systems in two- and three-dimensional spaces of constant curvature have been extensively studied. From these, superintegrable systems in conformally flat spaces can be constructed by Staeckel transform. In this paper a method developed ... More

Extended Kepler-Coulomb quantum superintegrable systems in 3 dimensionsOct 30 2012Nov 13 2012The quantum Kepler-Coulomb system in 3 dimensions is well known to be 2nd order superintegrable, with a symmetry algebra that closes polynomially under commutators. This polynomial closure is also typical for 2nd order superintegrable systems in 2D and ... More

Families of classical subgroup separable superintegrable systemsDec 16 2009We describe a method for determining a complete set of integrals for a classical Hamiltonian that separates in orthogonal subgroup coordinates. As examples, we use it to determine complete sets of integrals, polynomial in the momenta, for some families ... More

XMM-Newton Spectroscopy of Bright ULX Sources in the Antennae Galaxies (NGC 4038/4039)Feb 25 2003Mar 18 2004We report the results of spectral fits to four bright ultra-luminous X-ray sources (ULXs) in the Antennae galaxies (NGC 4038/4039) observed for 41 ksec with XMM-Newton. Although emission regions are not resolved as well as in prior Chandra observations, ... More

Loss in long-storage-time optical cavitiesOct 07 2013Oct 31 2013Long-storage-time Fabry-Perot cavities are a core component of many precision measurement experiments. Optical loss in such cavities is a critical parameter in determining their performance; however, it is very difficult to determine a priori from independent ... More

Chandra observations of the bursting X-ray transient SAX J1747.0-2853 during low-level accretion activityFeb 07 2002Jul 11 2002We present Chandra/ACIS observations of the bursting X-ray transient SAX J1747.0-2853 performed on 18 July 2001. We detected a bright source at the position of R.A = 17^h 47^m 02.60^s and Dec. = -28 52' 58.9'' (J2000.0; with a 1 sigma error of ~0.7 arcseconds), ... More

Performance characteristics of the new Keck Observatory echelle spectrograph and imagerOct 04 2000The Echelle Spectrograph and Imager (ESI) is a multipurpose instrument which has been delivered by the Instrument Development Laboratory of Lick Observatory for use at the Cassegrain focus of the Keck II telescope. ESI saw first light on August 29, 1999. ... More

CMB Beam Systematics: Impact on Lensing Parameter EstimationJun 18 2008Mar 20 2009The CMB's B-mode polarization provides a handle on several cosmological parameters most notably the tensor-to-scalar ratio, $r$, and is sensitive to parameters which govern the growth of large scale structure (LSS) and evolution of the gravitational potential. ... More

The BFKL Pomeron Calculus in zero transverse dimensions: diffractive processes and survival probability for central diffractive productionOct 09 2006Nov 07 2006In this paper we discuss the processes of diffractive production in the framework of the BFKL Pomeron calculus in zero transverse dimension. Considering the diffractive production of a bunch of particles with not very large masses, namely, $\ln\Lb M^2/m^2 ... More

Comment on ``Specific Heat and Shape Transitions in Light sd Nuclei''Sep 02 1994This comment re-examines the origin of structure seen in the computed specific heat of finite nuclei. In a recent paper, Civitarese and Schvellinger suggest that such structure is due to model-space truncation in the calculations. We reaffirm our conclusion ... More

On the observed disc temperature of accreting intermediate mass black holesAug 17 2004Some ultraluminous X-ray sources in nearby galaxies show soft components resembling thermal disc emission. Calculations based on blackbody emission then indicate that the accreting black holes at the centres of these discs have masses of 100s to 1000s ... More

A quaternion-based continuation method to follow the equilibria and stability of slender elastic rodsDec 22 2012We present a theoretical and numerical framework to compute bifurcations of equilibria and stability of slender elastic rods. The 3D kinematics of the rod is treated in a geometrically exact way by parameterizing the position of the centerline and making ... More

Coherent Contributions of Nuclear Mesons to Electroproduction and the HERMES EffectFeb 14 2000May 10 2000We show that nuclear sigma, omega, and pi mesons can contribute coherently to enhance the electroproduction cross section on nuclei for longitudinal virtual photons at low Q^2 while depleting the cross section for transverse photons. We are able to describe ... More

Thermal emission from the stellar-mass black hole binary XTE J1118+480 in the low/hard stateFeb 16 2009We report on the detection of a thermal-disk component from the stellar-mass black hole binary XTE J1118+480 in the canonical low/hard state. The presence of a thermal component with a temperature of approximately 0.21keV in the Chandra spectra of XTE ... More

Simulating Astro-H Observations of Sloshing Gas Motions in the Cores of Galaxy ClustersAug 18 2015Astro-H will be the first X-ray observatory to employ a high-resolution microcalorimeter, capable of measuring the shift and width of individual spectral lines to the precision necessary for estimating the velocity of the diffuse plasma in galaxy clusters. ... More

Rapid quantitative pharmacodynamic imaging by a novel method: theory, simulation testing and proof of principleApr 21 2013May 27 2014Pharmacological challenge imaging has mapped, but rarely quantified, the sensitivity of a biological system to a given drug. We describe a novel method called rapid quantitative pharmacodynamic imaging. This method combines pharmacokinetic-pharmacodynamic ... More

The Cluster of Galaxies Surrounding Cygnus A II: New Velocities and a Dynamical ModelMar 27 2005We have spectroscopically identified 77 new members of the Cygnus A cluster, bringing the total to 118 galaxies consistent with cluster membership. We use these data combined with the results from X-rays to deduce a dynamical model for the system. The ... More

Minimization of Transverse Wakefields in the NLC Accelerator StructuresAug 17 2002The progress of a multiple bunches of electrons through several thousand accelerator structures results in a wakefield which if left unchecked will kick successive bunches off the axis of the accelerator and can at the very least dilute the final luminosity ... More

Designing a single-molecule biophysics tool for characterizing DNA damage for techniques that kill infectious pathogens through DNA damage effectsMay 25 2016Antibiotics such as the quinolones and fluoroquinolones kill bacterial pathogens ultimately through DNA damage. They target the essential type IIA topoisomerases in bacteria by stabilising the normally transient double strand break state which is created ... More

Thermodynamic Consistency of the $q$-Deformed Fermi-Dirac Distribution in Nonextensive ThermostaticsJun 20 2010The $q$-deformed statistics for fermions arising within the non-extensive thermostatistical formalism has been applied to the study of various quantum many-body systems recently. The aim of the present note is to point out some subtle difficulties presented ... More

Pair Production of Smuons and Selectrons Near Threshold in e+ e- and e- e- CollisionsJun 18 2001Aug 17 2001Non-zero width and Coulomb rescattering effects are analyzed for the pair production of smuons and selectrons near the thresholds in e+ e- and e- e- collisions, respectively. The excitation curves are predicted in a gauge-invariant form. Energy cuts are ... More

A combinatorial identity for studying Sato-Tate type problemsJun 01 2010We derive a combinatorial identity which is useful in studying the distribution of Fourier coefficients of L-functions by allowing us to pass from knowledge of moments of the coefficients to the distribution of the coefficients.

Superintegrability and higher order constants for quantum systemsFeb 13 2010We refine a method for finding a canonical form for symmetry operators of arbitrary order for the Schroedinger eigenvalue equation on any 2D Riemannian manifold, real or complex, that admits a separation of variables in some orthogonal coordinate system. ... More

The Relativistic Fe Emission Line in XTE J1650-500 with BeppoSAX: Evidence for Black Hole Spin and Light Bending Effects?Nov 03 2003Mar 08 2004We report spectral results from three BeppoSAX observations of the black hole candidate XTE J1650-500 during its 2001/2002 outburst. We find strong evidence for the presence of a broad and strongly relativistic Fe emission line. The line profile indicates ... More

A Wind Accretion Model for HLX-1Feb 20 2014The brightest ultraluminous X-ray source currently known, HLX-1, has been observed to undergo five outburst cycles. The periodicity of these outbursts, and their high inferred maximum accretion rates of $\sim{\rm few}\times 10^{-4} M_\odot {\rm yr}^{-1}$, ... More

CMB Polarization Systematics Due to Beam Asymmetry: Impact on Cosmological BirefringenceMar 05 2009May 07 2009The standard cosmological model is assumed to respect parity symmetry. Under this assumption the cross-correlations of the CMB's temperature anisotropy and `gradient'-like polarization, with the `curl'-like polarization identically vanish over the full ... More

Black hole accretion disks in the canonical low-hard stateNov 06 2009Stellar-mass black holes in the low-hard state may hold clues to jet formation and basic accretion disk physics, but the nature of the accretion flow remains uncertain. A standard thin disk can extend close to the innermost stable circular orbit, but ... More

The Cosmological History of Accretion onto Dark Halos and Supermassive Black HolesAug 09 2006Aug 10 2006Aims: We investigate the cosmological growth of dark halos and follow the consequences of coeval growth for the accretion history of associated supermassive black holes. Methods: The Press-Schechter approximation is used to obtain an analytic expression ... More

The Neutralino Sector of the Next-to-Minimal Supersymmetric Standard ModelJul 19 2004The Next-to-Minimal Supersymmetric Standard Model (NMSSM) includes a Higgs iso-singlet superfield in addition to the two Higgs doublet superfields of the minimal extension. If the Higgs fields remain weakly coupled up to the GUT scale, as naturally motivated ... More

The Higgs Sector of the Next-to-Minimal Supersymmetric Standard ModelApr 04 2003Jun 04 2003The Higgs boson spectrum of the Next-to-Minimal Supersymmetric Standard Model is examined. The model includes a singlet Higgs field S in addition to the two Higgs doublets of the minimal extension. `Natural' values of the parameters of the model are motivated ... More

Next-to-leading order predictions for WW+jet productionJun 15 2015Aug 04 2015In this work we report on a next-to-leading order calculation of WW + jet production at hadron colliders, with subsequent leptonic decays of the W-bosons included. The calculation of the one-loop contributions is performed using generalized unitarity ... More

Nonextremal black holes are BPSDec 29 2006Jul 12 2007Extremal charged black holes are BPS solutions. It is commonly thought that their nonextremal counterparts are not. Further, experience with BPS solutions in flat spacetime suggests that all BPS solutions are supersymmetric; i.e. that they are invariant ... More

Semiclassical soliton ensembles for the three-wave resonant interaction equationsSep 18 2016The three-wave resonant interaction equations are a non-dispersive system of partial differential equations with quadratic coupling describing the time evolution of the complex amplitudes of three resonant wave modes. Collisions of wave packets induce ... More

Orbital X-Ray Variability of the Microquasar LS 5039Jul 18 2005The properties of the orbit and the donor star in the high mass X-ray binary microquasar LS 5039 indicate that accretion processes should mainly occur via a radiatively driven wind. In such a scenario, significant X-ray variability would be expected due ... More

X-ray emission from the Ultramassive Black Hole candidate NGC1277: implications and speculation on its originJan 09 2013We study the X-ray emission from NGC1277, a galaxy in the core of the Perseus cluster, for which van den Bosch et al. have recently claimed the presence of an UltraMassive Black Hole (UMBH) of mass 1.7 times 10^10 Msun, unless the IMF of the stars in ... More

Density diagnostics of ionized outflows in active galactic nuclei: X-ray and UV absorption lines from metastable levels in Be-like to C-like ionsJul 29 2017Aug 15 2017Ionized outflows in Active Galactic Nuclei (AGN) are thought to influence their nuclear and local galactic environment. However, the distance of the outflows with respect to the central engine is poorly constrained, which limits our understanding of their ... More

The Masses and Spins of Neutron Stars and Stellar-Mass Black HolesAug 18 2014Stellar-mass black holes and neutron stars represent extremes in gravity, density, and magnetic fields. They therefore serve as key objects in the study of multiple frontiers of physics. In addition, their origin (mainly in core-collapse supernovae) and ... More

Low accretion rates at the AGN cosmic downsizing epochSep 06 2007Context: X-ray surveys of Active Galactic Nuclei (AGN) indicate `cosmic downsizing', with the comoving number density of high-luminosity objects peaking at higher redshifts (z about 2) than low-luminosity AGN (z<1). Aims: We test whether downsizing is ... More

Quiescent X-ray variability from the neutron star transient Aql X-1Feb 24 2011A number of studies have revealed variability from neutron star low-mass X-ray binaries during quiescence. Such variability is not well characterised, or understood, but may be a common property that has been missed due to lack of multiple observations. ... More

Broad-band X-ray measurements of the black hole candidate XTE J1908+094May 30 2002Aug 27 2002XTE J1908+094 is an X-ray transient that went into outburst in February 2002. After two months it reached a 2-250 keV peak flux of 1 to 2 X 10-8 erg/s/cm2. Circumstantial evidence points to an accreting galactic black hole as the origin of the the X-radiation: ... More

A Very Large Array Search for Intermediate-Mass Black Holes in Globular Clusters in M81Apr 16 2016Nantais et al. used the Hubble Space Telescope to localize probable globular clusters (GCs) in M81, a spiral galaxy at a distance of 3.63 Mpc. Theory predicts that GCs can host intermediate-mass black holes (IMBHs) with masses M_BH \sim 100 - 100,000 ... More

Resolved Jets and Long-Period Black Hole X-ray NovaeFeb 12 2003Mar 18 2003In this brief note we point out that the four spatially resolved relativistic jets among the 14 dynamically confirmed black hole X-ray novae are all in systems with long orbital periods. Many shorter period systems show transient radio outbursts which ... More

Measuring the Spin of GRS 1915+105 with Relativistic Disk ReflectionSep 29 2009GRS 1915+105 harbors one of the most massive known stellar black holes in the Galaxy. In May 2007, we observed GRS 1915+105 for 117 ksec in the low/hard state using Suzaku. We collected and analyzed the data with the HXD/PIN and XIS cameras spanning the ... More

Effective medium theory of elastic waves in random networks of rodsJun 13 2012We formulate an effective medium (mean field) theory of a material consisting of randomly distributed nodes connected by straight slender rods, hinged at the nodes. Defining novel wavelength-dependent effective elastic moduli, we calculate both the static ... More

Broad relativistic iron emission line observed in SAX J1808.4-3658Jan 20 2009Feb 04 2009During the September-October 2008 outburst of the accreting millisecond pulsar SAX J1808.4-3658, the source was observed by both Suzaku and XMM-Newton approximately 1 day apart. Spectral analysis reveals a broad relativistic Fe K-alpha emission line which ... More

X-ray and UV Monitoring of the Seyfert 1.5 Galaxy Markarian 817Dec 17 2018We report the results of long-term simultaneous X-ray and UV monitoring of the nearby (z=0.03145) Seyfert 1.5 galaxy Mrk 817 using the Neil Gehrels Swift Observatory XRT and UVOT. Prior work has revealed that the X-ray flux from Mrk 817 has increased ... More

The BFKL Pomeron calculus: summing enhanced diagramsNov 15 2011Apr 26 2012The goal of this paper is to sum over a class of enhanced diagrams, and derive a new Pomeron Green function. It is found that this sum gives the Pomeron contribution to the scattering amplitude that decreases with energy. In other words, we found that ... More

Central exclusive diffractive Higgs boson production in hadron-nucleus and nucleus-nucleus collisions at the LHCJan 23 2008In this paper, it is shown that in hadron-nucleus and nucleus-nucleus collisions, the main source for central exclusive diffractive Higgs production is photon-photon fusion. At the LHC energy, the total cross section for this process is about 0.6 pb (for ... More

Two parton shower background for associate W Higgs productionMar 05 2008The estimates of the background for the associate W Higgs production, which stems from the two parton shower production. It is about 1 - 2.5 times larger than the signal. However, this background does not depend on the rapidity difference between the ... More

Pre- and post-selected ensembles and time-symmetry in quantum mechanicsFeb 26 2007An expression is proposed for the quantum mechanical state of a pre- and post-selected ensemble, which is an ensemble determined by the final as well as the initial state of the quantum systems involved. It is shown that the probabilities calculated from ... More

Quantum mechanics as a consistency condition on initial and final boundary conditionsJul 25 2006If the block universe view is correct, the future and the past have similar status and one would expect physical theories to involve final as well as initial boundary conditions. A plausible consistency condition between the initial and final boundary ... More

Counterfactual reasoning in time-symmetric quantum mechanicsOct 11 2004A qualification is suggested for the counterfactual reasoning involved in some aspects of time-symmetric quantum theory (which involves ensembles selected by both the initial and final states). The qualification is that the counterfactual reasoning should ... More