Results for "Shane L. Larson"

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Revealing black holes with GaiaOct 12 2017Nov 14 2017We estimate the population of black holes with luminous stellar companions (BH-LCs) in the Milky Way (MW) observable by Gaia. We evolve a realistic distribution of BH-LC progenitors from zero-age to the current epoch taking into account relevant physics, ... More
Null-stream pointing with pulsar timing arraysJul 12 2016Locating sources on the sky is one of the largest challenges in gravitational wave astronomy, owing to the omni-directional nature of gravitational wave detection techniques, and the often intrinsically weak signals being observed. Ground-based detectors ... More
Distinguishing Between Formation Channels for Binary Black Holes with LISAJun 30 2016Sep 22 2016The recent detections of GW150914 and GW151226 imply an abundance of stellar-mass binary-black-hole mergers in the local universe. While ground-based gravitational-wave detectors are limited to observing the final moments before a binary merges, space-based ... More
LISA sources in Milky Way globular clustersFeb 15 2018May 30 2018We explore the formation of double-compact-object binaries in Milky Way (MW) globular clusters (GCs) that may be detectable by the Laser Interferometer Space Antenna (LISA). We use a set of 137 fully evolved GC models that, overall, effectively match ... More
Constraining the Black Hole Mass Spectrum with Gravitational Wave Observations I: The Error KernelMar 11 2009Oct 15 2009Many scenarios have been proposed for the origin of the supermassive black holes (SMBHs) that are found in the centres of most galaxies. Many of these formation scenarios predict a high-redshift population of intermediate-mass black holes (IMBHs), with ... More
Addressing LISA Science Analysis ChallengesJun 21 2006The principal goal of the \emph{LISA Science Analysis Workshop} is to encourage the development and maturation of science analysis technology in preparation for LISA science operations. Exactly because LISA is a pathfinder for a new scientific discipline ... More
Low Frequency Gravitational Waves from White Dwarf MACHO BinariesMay 31 2000The possibility that Galactic halo MACHOs are white dwarfs has recently attracted much attention. Using the known properties of white dwarf binaries in the Galactic disk as a model, we estimate the possible contribution of halo white dwarf binaries to ... More
The LISA Optimal SensitivitySep 12 2002Jun 04 2003The multiple Doppler readouts available on the Laser Interferometer Space Antenna (LISA) permit simultaneous formation of several interferometric observables. All these observables are independent of laser frequency fluctuations and have different couplings ... More
Testing General Relativity with Low-Frequency, Space-Based Gravitational-Wave DetectorsDec 21 2012Sep 13 2013We review the tests of general relativity that will become possible with space-based gravitational-wave detectors operating in the ~0.01mHz - 1Hz low-frequency band. The fundamental aspects of gravitation that can be tested include the presence of additional ... More
Busting Up Binaries: Encounters Between Compact Binaries and a Supermassive Black HoleJan 26 2015Given the stellar density near the galactic center, close encounters between compact object binaries and the supermassive black hole are a plausible occurrence. We present results from a numerical study of close to 13 million such encounters. Consistent ... More
Post-Newtonian Dynamics in Dense Star Clusters: Binary Black Holes in the LISA BandNov 28 2018Feb 26 2019The dynamical processing of black holes in the dense cores of globular clusters (GCs), makes them efficient factories for producing binary black holes (BBHs). Here we explore the population of BBHs that form dynamically in GCs and may be observable at ... More
Determination of meteor showers on other planets using comet ephemeridesDec 23 1999Dec 04 2000Meteor showers on the Earth occur at well known times, and are associated with the decay of comets or other minor bodies whose orbital paths pass close to the Earth's trajectory. On the surface, determining the closest proximity of two orbital paths appears ... More
Astro2020 Science White Paper: Populations of Black Holes in BinariesApr 26 2019Black holes in binary star systems are vital for understanding the process of pr oducing gravitational wave sources, understanding how supernovae work, and for p roviding fossil evidence for the high mass stars from earlier in the Universe. At the present ... More
Can gravitational waves be detected in quasar microlensing?Jul 11 2000Studies of the lensed quasar ${\rm Q}0957+561 {\rm A,B}$ have shown evidence for microlensing in the brightness history of the quasar images. It had been suggested that a frequency offset between the brightness fluctuations in each of the two images might ... More
The LISA Time-Delay Interferometry Zero-Signal Solution. I: Geometrical PropertiesMay 30 2004Time-Delay Interferometry (TDI) is the data processing technique needed for generating interferometric combinations of data measured by the multiple Doppler readouts available onboard the three LISA spacecraft. Within the space of all possible interferometric ... More
The Discovery Potential of Space-Based Gravitational Wave AstronomyApr 02 2019A space-based interferometer operating in the previously unexplored mHz gravitational band has tremendous discovery potential. If history is any guide, the opening of a new spectral band will lead to the discovery of entirely new sources and phenomena. ... More
Evaluating Black Hole Detectability with LISAJul 06 2018Mar 06 2019We conduct an analysis of the measurement abilities of distinctive LISA detector designs, examining the influence of LISA's low-frequency performance on the detection and characterization of massive black hole binaries. We are particularly interested ... More
Astrophysical Bounds on Global StringsApr 09 1997Global topological defects produce nonzero stress-energy throughout spacetime, and as a result can have observable gravitational influence on surrounding matter. Gravitational effects of global strings are used to place bounds on their cosmic abundance. ... More
Gravitational wave bursts from the Galactic massive black holeDec 13 2006The Galactic massive black hole (MBH), with a mass of Mbh=3.6\times10^6 Solar masses, is the closest known MBH, at a distance of only 8 kpc. The proximity of this MBH makes it possible to observe gravitational waves from stars with periapse in the observational ... More
LISA data analysis: Source identification and subtractionJan 28 2003Jan 28 2003The Laser Interferometer Space Antenna (LISA) will operate as an AM/FM receiver for gravitational waves. For binary systems, the source location, orientation and orbital phase are encoded in the amplitude and frequency modulation. The same modulations ... More
Using binary stars to bound the mass of the gravitonDec 23 1999Interacting white dwarf binary star systems, including helium cataclysmic variable (HeCV) systems, are expected to be strong sources of gravitational radiation, and should be detectable by proposed space-based laser interferometer gravitational wave observatories ... More
Space missions to detect the cosmic gravitational-wave backgroundMar 21 2001Mar 24 2001It is thought that a stochastic background of gravitational waves was produced during the formation of the universe. A great deal could be learned by measuring this Cosmic Gravitational-wave Background (CGB), but detecting the CGB presents a significant ... More
Gravity Spy: Integrating Advanced LIGO Detector Characterization, Machine Learning, and Citizen ScienceNov 14 2016Feb 28 2017(abridged for arXiv) With the first direct detection of gravitational waves, the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) has initiated a new field of astronomy by providing an alternate means of sensing the universe. The extreme ... More
Multi-Messenger Astrophysics with Pulsar Timing ArraysMar 18 2019Pulsar timing arrays (PTAs) are on the verge of detecting low-frequency gravitational waves (GWs) from supermassive black hole binaries (SMBHBs). With continued observations of a large sample of millisecond pulsars, PTAs will reach this major milestone ... More
Accreting Double white dwarf binaries: Implications for LISAJul 04 2017Sep 12 2017We explore the long-term evolution of mass-transferring white dwarf binaries undergoing both direct-impact and disk accretion and explore implications of such systems to gravitational wave astronomy. We cover a broad range of initial component masses ... More
Sensitivity curves for spaceborne gravitational wave interferometersSep 26 1999Jan 10 2000To determine whether particular sources of gravitational radiation will be detectable by a specific gravitational wave detector, it is necessary to know the sensitivity limits of the instrument. These instrumental sensitivities are often depicted (after ... More
Specific Angular Momentum of Extrasolar Planetary SystemsAug 13 2007Sep 02 2011As the number of known planetary systems increases, the ability to follow-up and characterize the extent of any system becomes limited. This paper considers the use of specific angular momentum as a metric to prioritize future observations. We analyze ... More
Constraining the properties of the proposed supermassive black hole system in 3c66b: Limits from pulsar timingOct 09 2003Oct 10 2003Data from long term timing observations of the radio pulsar PSR B1855+09 have been searched for the signature of Gravitational waves (G-waves) emitted by the proposed supermassive binary black hole system in 3C66B. For the case of a circular orbit, the ... More
Unequal arm space-borne gravitational wave detectorsJun 26 2002Unlike ground-based interferometric gravitational wave detectors, large space-based systems will not be rigid structures. When the end-stations of the laser interferometer are freely flying spacecraft, the armlengths will change due to variations in the ... More
Gravitational radiation timescales for extreme mass ratio inspiralsAug 11 2005Nov 17 2005The capture and inspiral of compact stellar masses into massive black holes is an important source of low-frequency gravitational waves (with frequencies of ~1-100mHz), such as those that might be detected by the planned Laser Interferometer Space Antenna ... More
Integrated Sachs-Wolfe Effect for Gravitational RadiationMay 12 2009Apr 15 2010Gravitational waves are messengers carrying valuable information about their sources. For sources at cosmological distances, the waves will contain also the imprint left by the intervening matter. The situation is in close analogy with cosmic microwave ... More
Limiting alternative theories of gravity using gravitational wave observations across the spectrumNov 13 2013Nov 13 2014The advent of gravitational wave astronomy provides new proving grounds for testing theories of gravity. Recent work has reinvigorated the study of bimetric theories of gravity and massive gravity theories. One of the most interesting predictions of these ... More
Semi-relativistic approximation to gravitational radiation from encounters with nonspinning black holesAug 11 2005Jan 04 2007The capture of compact bodies by black holes in galactic nuclei is an important prospective source for low frequency gravitational wave detectors, such as the planned Laser Interferometer Space Antenna. This paper calculates, using a semirelativistic ... More
LISA, binary stars, and the mass of the gravitonSep 26 2002We extend and improve earlier estimates of the ability of the proposed LISA (Laser Interferometer Space Antenna) gravitational wave detector to place upper bounds on the graviton mass, m_g, by comparing the arrival times of gravitational and electromagnetic ... More
Semiclassical effects in black hole interiorsJan 03 1997First-order semiclassical perturbations to the Schwarzschild black hole geometry are studied within the black hole interior. The source of the perturbations is taken to be the vacuum stress-energy of quantized scalar, spinor, and vector fields, evaluated ... More
Detecting a Stochastic Gravitational-Wave Background: The Overlap Reduction FunctionNov 21 2008Apr 30 2009Detection of a gravitational-wave stochastic background via ground or space-based gravitational-wave detectors requires the cross-correlation of the response of two or more independent detectors. The cross-correlation involves a frequency-dependent factor ... More
Null geodesics in the Alcubierre warp drive spacetime: the view from the bridgeJul 06 1999The null geodesic equations in the Alcubierre warp drive spacetime are numerically integrated to determine the angular deflection and redshift of photons which propagate through the distortion of the ``warp drive'' bubble to reach an observer at the origin ... More
Contribution of Compact Mass Transferring Systems to the Galactic Gravitational Wave BackgroundOct 25 2005Nov 01 2008Compact object binaries, mostly double with dwarfs, are believed to be a potential source of confusion-limited noise for the Laser Interferometer Space Antenna (LISA). In a specific frequency range, this noise may rise above the instrumental noise sources ... More
Detecting circumbinary exoplanets and hierarchical stellar triples with the LISA gravitational radiation missionDec 09 2018We investigate the possibility of detecting planetary or stellar companions orbiting white dwarf binaries using the LISA gravitational radiation detector. Specifically, we consider the acceleration of the barycenter of the white dwarf binary due to the ... More
LISA data analysis I: Doppler demodulationJun 06 2002Jun 13 2002The orbital motion of the Laser Interferometer Space Antenna (LISA) produces amplitude, phase and frequency modulation of a gravitational wave signal. The modulations have the effect of spreading a monochromatic gravitational wave signal across a range ... More
On the power mean of a sum analogous to the Kloosterman sumDec 05 2017In this paper, we study the power mean of a sum analogous to the Kloosterman sum by using analytic methods for character sums.
Note on the truncated generalizations of Gauss' square exponent theoremMar 26 2018In this note, we investigate J.-C. Liu's work on truncated Gauss' square exponent theorem and obtain more truncations. We also discuss some possible multiple summation extensions of Liu's results.
Partitions and the maximal excludantMay 15 2019For each nonempty integer partition $\pi$, we define the maximal excludant of $\pi$ to be the largest nonnegative integer smaller than the largest part of $\pi$ that is not a part of $\pi$. Let $\sigma\!\operatorname{maex}(n)$ be the sum of maximal excludants ... More
Hands-on Gravitational Wave Astronomy: Extracting astrophysical information from simulated signalsOct 04 2006In this paper we introduce a hands-on activity in which introductory astronomy students act as gravitational wave astronomers by extracting information from simulated gravitational wave signals. The process mimics the way true gravitational wave analysis ... More
Gravitational Waves: new observatories for new astronomySep 23 2005This article reviews the current status of gravitational wave astronomy and explains why astronomers are excited about the new generation of gravitational wave detectors. As part of the review we compare and contrast gravitational radiation to the more ... More
Science Icebreaker Activities: An Example from Gravitational Wave AstronomyMar 25 2005Sep 26 2005At the beginning of a class or meeting an icebreaker activity is often used to help loosen the group and get everyone talking. Our motivation is to develop activities that serve the purpose of an icebreaker, but are designed to enhance and supplement ... More
A bound for the perimeter of inner parallel bodiesAug 26 2015Mar 04 2016We provide a sharp lower bound for the perimeter of the inner parallel sets of a convex body $\Omega$. The bound depends only on the perimeter and inradius $r$ of the original body and states that \[|\partial\Omega_t| \geq \Bigl(1-\frac{t}{r}\Bigr)^{n-1}_+ ... More
The Integral Chow Ring of $\bar{M}_2$Apr 17 2019In this paper we compute the Chow ring of the moduli stack $\bar{M}_2$ of stable curves of genus 2 with integral coefficients.
The Generality of a Section of a CurveMay 20 2016Sep 18 2018Let f: C --> P^3 be a general curve of genus g, mapped to P^3 via a general linear series of degree d; and let Q be a general (and thus smooth) quadric. In this paper, we show that the points of intersection f(C) \cap Q give a general collection of 2d ... More
Coefficients of McKay-Thompson series and distributions of the moonshine moduleAug 15 2015Jan 03 2016In a recent paper, Duncan, Griffin and Ono provide exact formulas for the coefficients of McKay-Thompson series and use them to find asymptotic expressions for the distribution of irreducible representations in the moonshine module $V^\natural = \bigoplus_n ... More
Observing IMBH-IMBH Binary Coalescences via Gravitational RadiationMay 30 2006Jun 21 2006Recent numerical simulations have suggested the possibility of forming double intermediate mass black holes (IMBHs) via the collisional runaway scenario in young dense star clusters. The two IMBHs formed would exchange into a common binary shortly after ... More
Astro2020 Decadal Science White Paper: The state of gravitational-wave astrophysics in 2020Mar 11 2019While still in its infancy, the budding field of gravitational-wave astronomy has so far exceeded most expectations, and the achievements that have already been made bode well for the decade to come. While the discoveries made possible by LIGO have captured ... More
Characterizing accreting double white dwarf binaries with the Laser Interferometer Space Antenna and GaiaOct 23 2017Apr 30 2018We demonstrate a method to fully characterize mass-transferring double white dwarf (DWD) systems with a helium-rich (He) WD donor based on the mass--radius relationship for He WDs. Using a simulated Galactic population of DWDs, we show that donor and ... More
The Testbed for LISA Analysis ProjectFeb 05 2006The Testbed for LISA Analysis (TLA) Project aims to facilitate the development, validation and comparison of different methods for LISA science data analysis, by the broad LISA Science Community, to meet the special challenges that LISA poses. It includes ... More
Prospects for observing ultra-compact binaries with space-based gravitational wave interferometers and optical telescopesJul 20 2012Aug 24 2012Space-based gravitational wave interferometers are sensitive to the galactic population of ultra-compact binaries. An important subset of the ultra-compact binary population are those stars that can be individually resolved by both gravitational wave ... More
$K$-theory of valuation ringsOct 29 2018We prove several results showing that the algebraic $K$-theory of valuation rings behave as though such rings were regular Noetherian, in particular an analogue of the Geisser--Levine theorem. We also give some new proofs of known results concerning cdh ... More
Fibre HomogenisationJun 02 2017In this article we present a novel method for studying the asymptotic behaviour, with order-sharp error estimates, of the resolvents of parameter-dependent operator families. The method is applied to the study of differential equations with rapidly oscillating ... More
Classification of real rational knots of low degree in the 3-sphereNov 15 2013In this paper we classify, up to rigid isotopy, non-singular real rational curves of degrees less than or equal to 6 in a quadric homeomorphic to the 3-sphere. We also study their connections with rigid isotopy classes of real rational knots in $\mathbb{RP}^3$. ... More
Homogenisation with error estimates of attractors for damped semi-linear anisotropic wave equationsApr 26 2018Homogenisation of global $\mathcal{A}^\epsilon$ and exponential $\mathcal{M}^\epsilon$ attractors for the damped semi-linear anisotropic wave equation $\partial_t^2 u^\epsilon +\gamma\partial_t u^\epsilon-{\rm div} \left(a\left( \tfrac{x}{\epsilon} \right)\nabla ... More
Event rate estimates for LISA extreme mass ratio capture sourcesMay 28 2004One of the most exciting prospects for the LISA gravitational wave observatory is the detection of gravitational radiation from the inspiral of a compact object into a supermassive black hole. The large inspiral parameter space and low amplitude of the ... More
A Truth Serum for Sharing RewardsMay 22 2013We study a problem where a group of agents has to decide how a joint reward should be shared among them. We focus on settings where the share that each agent receives depends on the subjective opinions of its peers concerning that agent's contribution ... More
Congruence properties of Taylor coefficients of modular formsJun 11 2014In their work, Serre and Swinnerton-Dyer study the congruence properties of the Fourier coefficients of modular forms. We examine similar congruence properties, but for the coefficients of a modified Taylor expansion about a CM point $\tau$. These coefficients ... More
Determinants of Subquotients of Galois Representations Associated to Abelian VarietiesOct 03 2011Mar 30 2012Given an abelian variety $A$ of dimension $g$ over a number field $K$, and a prime $\ell$, the $\ell^n$-torsion points of $A$ give rise to a representation $\rho_{A, \ell^n} : \gal(\bar{K} / K) \to \gl_{2g}(\zz/\ell^n\zz)$. In particular, we get a mod-$\ell$ ... More
On a Reliable Peer-Review ProcessApr 26 2012Jun 26 2013We propose an enhanced peer-review process where the reviewers are encouraged to truthfully disclose their reviews. We start by modelling that process using a Bayesian model where the uncertainty regarding the quality of the manuscript is taken into account. ... More
Linear independence in the rational homology cobordism groupMar 21 2018We give simple homological conditions for a rational homology 3-sphere Y to have infinite order in the rational homology cobordism group, and for a collection of rational homology spheres to be linearly independent. These translate immediately to statements ... More
M-curves and symmetric productsMar 01 2016Let $(X , \sigma)$ be a geometrically irreducible smooth projective M-curve of genus $g$ defined over the field of real numbers. We prove that the $n$-th symmetric product of $(X , \sigma)$ is an M-variety for $n=2 ,3$ and $n\geq 2g -1$.
The Optical and Near-Infrared Transmission Spectrum of the Super-Earth GJ1214b: Further Evidence for a Metal-Rich AtmosphereSep 03 2011Oct 26 2011We present an investigation of the transmission spectrum of the 6.5 M_earth planet GJ1214b based on new ground-based observations of transits of the planet in the optical and near-infrared, and on previously published data. Observations with the VLT+FORS ... More
On the convergence of the normal form transformation in discrete Rossby and drift wave turbulenceApr 30 2019We study numerically the region of convergence of the normal form transformation for the case of the Charney-Hasagawa-Mima (CHM) equation to investigate whether certain finite amplitude effects can be described in normal coordinates. We do this by taking ... More
A Queuing Model for CPU Functional Unit and Issue Queue ConfigurationJul 19 2018In a superscalar processor, instructions of various types flow through an execution pipeline, traversing hardware resources which are mostly shared among many different instruction types. A notable exception to shared pipeline resources is the collection ... More
Angular Momentum Transport in Accretion Disks and its Implications for Spin Estimates in Black Hole BinariesMar 05 2008Jun 06 2008The accretion flow in the disk dominated state of black hole binaries has peak temperature and luminosity which vary together in such a way as to indicate an approximately constant emitting area. The association of this with the last stable orbit gives ... More
Line driven winds and the UV turnover in AGN accretion discsDec 12 2013Dec 29 2013AGN SEDs generally show a turnover at lambda 1000A, implying a maximal accretion disc (AD) temperature of T_max~50,000K. Massive O stars display a similar T_max, associated with a sharp rise in a line driven mass loss Mdot_wind with increasing surface ... More
Constructing real rational knots by gluingAug 13 2016We show that the problem of constructing a real rational knot of a reasonably low degree can be reduced to an algebraic problem involving the pure braid group: expressing an associated element of the pure braid group in terms of the standard generators ... More
Splitting stationary sets from weak forms of ChoiceMar 12 2010Working in the context of restricted forms of the Axiom of Choice, we consider the problem of splitting the ordinals below $\lambda$ of cofinality $\theta$ into $\lambda$ many stationary sets, where $\theta < \lambda$ are regular cardinals. This is a ... More
The Stationary Set Splitting GameMar 11 2010The \emph{stationary set splitting game} is a game of perfect information of length $\omega_{1}$ between two players, \unspls and \spl, in which \unspls chooses stationarily many countable ordinals and \spls tries to continuously divide them into two ... More
Knot concordance and homology sphere groupsMay 25 2016Apr 25 2017We study two homomorphisms to the rational homology sphere group. If $\psi$ denotes the inclusion homomorphism from the integral homology sphere group, then using work of Lisca we show that the image of $\psi$ intersects trivially with the subgroup of ... More
Asymptotic behaviour of cuboids optimising Laplacian eigenvaluesMar 29 2017Oct 10 2017We prove that in dimension $n \geq 2$, within the collection of unit measure cuboids in $\mathbb{R}^n$ (i.e. domains of the form $\prod_{i=1}^{n}(0, a_n)$), any sequence of minimising domains $R_k^\mathcal{D}$ for the Dirichlet eigenvalues $\lambda_k$ ... More
Coxeter Groups and Wavelet SetsOct 19 2007A traditional wavelet is a special case of a vector in a separable Hilbert space that generates a basis under the action of a system of unitary operators defined in terms of translation and dilation operations. A Coxeter/fractal-surface wavelet is obtained ... More
Admissible sequences for positive operatorsJan 14 2018A sequence of scalars is said to be admissible for a positive operator A on a Hilbert space if it is the diagonal of VAV* for some partial isometry V having as domain the closure of the range of A. When A is a projection, the celebrated Kadison's carpenter ... More
A Consensual Linear Opinion PoolApr 24 2012Apr 09 2013An important question when eliciting opinions from experts is how to aggregate the reported opinions. In this paper, we propose a pooling method to aggregate expert opinions. Intuitively, it works as if the experts were continuously updating their opinions ... More
Scott processesJul 08 2014The Scott process of a relational structure $M$ is the sequence of sets of formulas given by the Scott analysis of $M$. We present axioms for the class of Scott processes of structures in a relational vocabulary $\tau$, and use them to give a proof of ... More
On the Surjectivity of Galois Representations Associated to Elliptic Curves over Number FieldsMar 30 2012Given an elliptic curve $E$ over a number field $K$, the $\ell$-torsion points $E[\ell]$ of $E$ define a Galois representation $\gal(\bar{K}/K) \to \gl_2(\ff_\ell)$. A famous theorem of Serre states that as long as $E$ has no Complex Multiplication (CM), ... More
Hyperbolicity of the partition Jensen polynomialsApr 29 2019Given an arithmetic function $a: \mathbb{N} \rightarrow \mathbb{R}$, one can associate a naturally defined, doubly infinite family of Jensen polynomials. Recent work of Griffin, Ono, Rolen, and Zagier shows that for certain families of functions $a: \mathbb{N} ... More
Sharing a Reward Based on Peer EvaluationsJun 03 2013We study a problem where a group of agents has to decide how some fixed value should be shared among them. We are interested in settings where the share that each agent receives is based on how that agent is evaluated by other members of the group, where ... More
Exclusion bounds for extended anyonsAug 16 2016Aug 30 2017We introduce a rigorous approach to the many-body spectral theory of extended anyons, i.e. quantum particles confined to two dimensions that interact via attached magnetic fluxes of finite extent. Our main results are many-body magnetic Hardy inequalities ... More
Post-Newtonian Dynamics in Dense Star Clusters: Binary Black Holes in the LISA BandNov 28 2018The dynamical processing of black holes in the dense cores of globular clusters (GCs), makes them efficient factories for producing binary black holes (BBHs). Here we explore the population of BBHs that form dynamically in GCs and may be observable at ... More
Multimessenger science opportunities with mHz gravitational wavesMar 11 2019LISA will open the mHz band of gravitational waves (GWs) to the astronomy community. The strong gravity which powers the variety of GW sources in this band is also crucial in a number of important astrophysical processes at the current frontiers of astronomy. ... More
The Catalina Real-time Transient SurveyNov 10 2011The Catalina Real-time Transient Survey (CRTS) currently covers 33,000 deg^2 of the sky in search of transient astrophysical events, with time baselines ranging from 10 minutes to ~7 years. Data provided by the Catalina Sky Survey provides an unequaled ... More
Discovery of the Extremely Energetic Supernova 2008fzAug 13 2009Oct 24 2009We report on the discovery and initial observations of the energetic type IIn supernova (SN), 2008fz. The optical energy emitted by SN 2008fz (based on the light curve over a 88 day period), is possibly the most ever observed for a supernova (1.4 x 10^51 ... More
Ultrafast Triplet Pair Formation and Subsequent Thermally Activated Dissociation Control Efficient Endothermic Singlet Exciton FissionApr 06 2017Singlet exciton fission (SF), the conversion of one spin-singlet exciton (S1) into two spin-triplet excitons (T1), could provide a means to overcome the Shockley-Queisser limit in photovoltaics. SF as measured by the decay of S1 has been shown to occur ... More
Astro2020 Decadal Science White Paper: Gravitational Wave Survey of Galactic Ultra Compact BinariesMar 13 2019Ultra-compact binaries (UCBs) are systems containing compact or degenerate stars with orbital periods less than one hour. Tens of millions of UCBs are predicted to exist within theGalaxy emitting gravitational waves (GWs) at mHz frequencies. Combining ... More
Laser Interferometer Space AntennaFeb 02 2017Feb 23 2017Following the selection of The Gravitational Universe by ESA, and the successful flight of LISA Pathfinder, the LISA Consortium now proposes a 4 year mission in response to ESA's call for missions for L3. The observatory will be based on three arms with ... More
MHz Gravitational Wave Constraints with Decameter Michelson InterferometersNov 17 2016A new detector, the Fermilab Holometer, consists of separate yet identical 39-meter Michelson interferometers. Strain sensitivity achieved is better than $10^{-21} /{\sqrt{\rm{Hz}}}$ between 1 to 13 MHz from a 130-hr dataset. This measurement exceeds ... More
Metasurface Optics for Full-color Computational ImagingFeb 11 2018Conventional imaging systems comprise large and expensive optical components which successively mitigate aberrations. Metasurface optics offers a route to miniaturize imaging systems by replacing bulky components with flat and compact implementations. ... More
Tunable metasurfaces via subwavelength phase shifters with uniform amplitudeOct 06 2016Jan 09 2017Metasurfaces with tunable spatial phase functions could benefit numerous applications. Currently, most approaches to tuning rely on mechanical stretching which cannot control phase locally, or by modulating the refractive index to exploit rapid phase ... More
Audio Spectrogram Factorization for Classification of Telephony Signals below the Auditory ThresholdNov 09 2018Traffic Pumping attacks are a form of high-volume SPAM that target telephone networks, defraud customers and squander telephony resources. One type of call in these attacks is characterized by very low-amplitude signal levels, notably below the auditory ... More
Computational Method for Phase Space Transport with Applications to Lobe Dynamics and Rate of EscapeNov 04 2017Lobe dynamics and escape from a potential well are general frameworks introduced to study phase space transport in chaotic dynamical systems. While the former approach studies how regions of phase space are transported by reducing the flow to a two-dimensional ... More
Tuning the disorder of superglassesFeb 17 2012Aug 28 2012We study the interplay of superfluidity, glassy and magnetic orders of hardcore bosons with random frustrating interactions. In the classical limit, this model reduces to a $\pm J$ Edwards-Anderson Ising model with concentration $p$ of the ferromagnetic ... More
Agents and Devices: A Relative Definition of AgencyMay 31 2018According to Dennett, the same system may be described using a `physical' (mechanical) explanatory stance, or using an `intentional' (belief- and goal-based) explanatory stance. Humans tend to find the physical stance more helpful for certain systems, ... More
Turbulent Comptonization in Relativistic Accretion DisksSep 28 2006Turbulent Comptonization, a potentially important damping and radiation mechanism in relativistic accretion flows, is discussed. Particular emphasis is placed on the physical basis, relative importance, and thermodynamics of turbulent Comptonization. ... More
The emergence of giant multicaloric phenomena near room temperatureFeb 24 2016Caloric responses (temperature changes) can be induced in solid-state materials by applying external stimuli such as stress, pressure, and electric and magnetic fields. The magnetic-field-stimulated response is called the magnetocaloric effect, and materials ... More