P. L. Kelly - UC Berkeley

P. L. Kelly
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Name
P. L. Kelly
Affiliation
UC Berkeley
City
Berkeley
Country
United States

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High Energy Astrophysical Phenomena (14)
 
Cosmology and Nongalactic Astrophysics (14)
 
Solar and Stellar Astrophysics (12)
 
Astrophysics of Galaxies (11)
 
Physics - Mesoscopic Systems and Quantum Hall Effect (6)
 
Computer Science - Distributed; Parallel; and Cluster Computing (5)
 
Physics - Materials Science (4)
 
Computer Science - Mathematical Software (4)
 
Computer Science - Performance (3)
 
Computer Science - Computer Vision and Pattern Recognition (3)
 
Computer Science - Robotics (2)
 
Mathematics - Numerical Analysis (1)
 
Computer Science - Computational Engineering; Finance; and Science (1)
 
Computer Science - Numerical Analysis (1)
 
Computer Science - Logic in Computer Science (1)
 
Computer Science - Learning (1)
 
Instrumentation and Methods for Astrophysics (1)

Publications Authored By P. L. Kelly

We report the first results from our long-term observational survey aimed at discovering late-time interaction between the ejecta of hydrogen-poor Type I supernovae and the hydrogen-rich envelope expelled from the progenitor star several decades/centuries before explosion. The expelled envelope, moving with a velocity of ~10 -- 100 km s$^{-1}$, is expected to be caught up by the fast-moving SN ejecta several years/decades after explosion depending on the history of the mass-loss process acting in the progenitor star prior to explosion. The collision between the SN ejecta and the circumstellar envelope results in net emission in the Balmer-lines, especially in H-alpha. Read More

The Wide Field InfraRed Survey Telescope (WFIRST) was the highest ranked large space-based mission of the 2010 New Worlds, New Horizons decadal survey. It is now a NASA mission in formulation with a planned launch in the mid-2020's. A primary mission objective is to precisely constrain the nature of dark energy through multiple probes, including Type Ia supernovae (SNe Ia). Read More

2017Feb
Authors: L. Pei, M. M. Fausnaugh, A. J. Barth, B. M. Peterson, M. C. Bentz, G. De Rosa, K. D. Denney, M. R. Goad, C. S. Kochanek, K. T. Korista, G. A. Kriss, R. W. Pogge, V. N. Bennert, M. Brotherton, K. I. Clubb, E. Dalla Bontà, A. V. Filippenko, J. E. Greene, C. J. Grier, M. Vestergaard, W. Zheng, Scott M. Adams, Thomas G. Beatty, A. Bigley, Jacob E. Brown, Jonathan S. Brown, G. Canalizo, J. M. Comerford, Carl T. Coker, E. M. Corsini, S. Croft, K. V. Croxall, A. J. Deason, Michael Eracleous, O. D. Fox, E. L. Gates, C. B. Henderson, E. Holmbeck, T. W. -S. Holoien, J. J. Jensen, C. A. Johnson, P. L. Kelly, S. Kim, A. King, M. W. Lau, Miao Li, Cassandra Lochhaas, Zhiyuan Ma, E. R. Manne-Nicholas, J. C. Mauerhan, M. A. Malkan, R. McGurk, L. Morelli, Ana Mosquera, Dale Mudd, F. Muller Sanchez, M. L. Nguyen, P. Ochner, B. Ou-Yang, A. Pancoast, Matthew T. Penny, A. Pizzella, Radosław Poleski, Jessie Runnoe, B. Scott, Jaderson S. Schimoia, B. J. Shappee, I. Shivvers, Gregory V. Simonian, A. Siviero, Garrett Somers, Daniel J. Stevens, M. A. Strauss, Jamie Tayar, N. Tejos, T. Treu, J. Van Saders, L. Vican, S. Villanueva Jr., H. Yuk, N. L. Zakamska, W. Zhu, M. D. Anderson, P. Arévalo, C. Bazhaw, S. Bisogni, G. A. Borman, M. C. Bottorff, W. N. Brandt, A. A. Breeveld, E. M. Cackett, M. T. Carini, D. M. Crenshaw, A. De Lorenzo-Cáceres, M. Dietrich, R. Edelson, N. V. Efimova, J. Ely, P. A. Evans, G. J. Ferland, K. Flatland, N. Gehrels, S. Geier, J. M. Gelbord, D. Grupe, A. Gupta, P. B. Hall, S. Hicks, D. Horenstein, Keith Horne, T. Hutchison, M. Im, M. D. Joner, J. Jones, J. Kaastra, S. Kaspi, B. C. Kelly, J. A. Kennea, M. Kim, S. C. Kim, S. A. Klimanov, J. C. Lee, D. C. Leonard, P. Lira, F. MacInnis, S. Mathur, I. M. McHardy, C. Montouri, R. Musso, S. V. Nazarov, H. Netzer, R. P. Norris, J. A. Nousek, D. N. Okhmat, I. Papadakis, J. R. Parks, J. -U. Pott, S. E. Rafter, H. -W. Rix, D. A. Saylor, K. Schnülle, S. G. Sergeev, M. Siegel, A. Skielboe, M. Spencer, D. Starkey, H. -I. Sung, K. G. Teems, C. S. Turner, P. Uttley, C. Villforth, Y. Weiss, J. -H. Woo, H. Yan, S. Young, Y. Zu

We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multi-wavelength reverberation mapping campaign. The campaign spanned six months and achieved an almost daily cadence with observations from five ground-based telescopes. The H$\beta$ and He II $\lambda$4686 broad emission-line light curves lag that of the 5100 $\AA$ optical continuum by $4. Read More

In this paper we investigate an emerging application, 3D scene understanding, likely to be significant in the mobile space in the near future. The goal of this exploration is to reduce execution time while meeting our quality of result objectives. In previous work we showed for the first time that it is possible to map this application to power constrained embedded systems, highlighting that decision choices made at the algorithmic design-level have the most impact. Read More

With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, that sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF13dqy = SN 2013fs, a mere ~3 hr after explosion. Read More

We investigate a new empirical fitting method for the optical light curves of Type Ia supernovae (SNe~Ia) that is able to estimate the first-light time of SNe~Ia, even when they are not discovered extremely early. With an improved ability to estimate the time of first light for SNe Ia, we compute the rise times for a sample of 56 well-observed SNe~Ia. We find rise times ranging from 10. Read More

SN2005ip was a TypeIIn event notable for its sustained strong interaction with circumstellar material (CSM), coronal emission lines, and IR excess, interpreted as shock interaction with the very dense and clumpy wind of an extreme red supergiant. We present a series of late-time spectra of SN2005ip and a first radio detection of this SN, plus late-time X-rays, all of which indicate that its CSM interaction is still strong a decade post-explosion. We also present and discuss new spectra of geriatric SNe with continued CSM interaction: SN1988Z, SN1993J, and SN1998S. Read More

2016Nov
Affiliations: 1STScI, 2IPAC/Caltech, 3NASA Goddard, 4Steward Observatory, 5UC Berkeley, 6Steward Observatory, 7CRESST/UMBC/GSFC, 8UC Santa Cruz/University of Illinois, 9UC Berkeley, 10JPL/Caltech, 11UC Berkeley

The nature of the progenitor star (or system) for the Type IIn supernova (SN) subclass remains uncertain. While there are direct imaging constraints on the progenitors of at least four Type IIn supernovae, one of them being SN 2010jl, ambiguities remain in the interpretation of the unstable progenitors and the explosive events themselves. A blue source in pre-explosion HST/WFPC2 images falls within the 5 sigma astrometric error circle derived from post-explosion ground-based imaging of SN 2010jl. Read More

Herein we analyse late-time (post-plateau; 103 < t < 1229 d) optical spectra of low-redshift (z < 0.016), hydrogen-rich Type IIP supernovae (SNe IIP). Our newly constructed sample contains 91 nebular spectra of 38 SNe IIP, which is the largest dataset of its kind ever analysed in one study, and many of the objects have complementary photometric data. Read More

We present optical spectra of the nearby Type Ia supernova SN 2011fe at 100, 205, 311, 349, and 578 days post-maximum light, as well as an ultraviolet spectrum obtained with Hubble Space Telescope at 360 days post-maximum light. We compare these observations with synthetic spectra produced with the radiative transfer code PHOENIX. The day +100 spectrum can be well fit with models which neglect collisional and radiative data for forbidden lines. Read More

We present a low energy Hamiltonian generalized to describe how the energy bands of germanene ($\rm \overline{Ge}$) are modified by interaction with a substrate or a capping layer. The parameters that enter the Hamiltonian are determined from first-principles relativistic calculations for $\rm \overline{Ge}|$MoS$_2$ bilayers and MoS$_2|\rm \overline{Ge} |$MoS$_2$ trilayers and are used to determine the topological nature of the system. For the lowest energy, buckled germanene structure, the gap depends strongly on how germanene is oriented with respect to the MoS$_2$ layer(s). Read More

2016Jun
Affiliations: 1KIPAC Stanford/SLAC, 2KIPAC Stanford/SLAC, 3KIPAC Stanford/SLAC, 4Stony Brook, 5Bonn, 6UC Berkeley, 7KIPAC Stanford/SLAC, 8IfA Hawaii, 9IfA Hawaii

We present constraints on the scaling relations of galaxy cluster X-ray luminosity, temperature and gas mass (and derived quantities) with mass and redshift, employing masses from robust weak gravitational lensing measurements. These are the first such results obtained from an analysis that simultaneously accounts for selection effects and the underlying mass function, and directly incorporates lensing data to constrain total masses. Our constraints on the scaling relations and their intrinsic scatters are in good agreement with previous studies, and reinforce a picture in which departures from self-similar scaling laws are primarily limited to cluster cores. Read More

We present an algorithm for the optimization of a class of finite element integration loop nests. This algorithm, which exploits fundamental mathematical properties of finite element operators, is proven to achieve a locally optimal operation count. In specified circumstances the optimum achieved is global. Read More

We present a generic algorithm for numbering and then efficiently iterating over the data values attached to an extruded mesh. An extruded mesh is formed by replicating an existing mesh, assumed to be unstructured, to form layers of prismatic cells. Applications of extruded meshes include, but are not limited to, the representation of 3D high aspect ratio domains employed by geophysical finite element simulations. Read More

Supernova (SN) 2015U (also known as PSN J07285387+3349106) was discovered in NGC 2388 on 2015 Feb. 11. A rapidly evolving and luminous event, it showed effectively hydrogen-free spectra dominated by relatively narrow helium P-Cygni spectral features and it was classified as a SN Ibn. Read More

To study the effect of spin-orbit coupling (SOC) on spin-transfer torque in magnetic materials, we have implemented two theoretical formalisms that can accommodate SOC. Using the "charge-pumping" formalism, we find two contributions to the out-of-plane spin-transfer torque parameter $\beta$ in ballistic Ni domain walls (DWs). For short DWs, the nonadiabatic reflection of conduction electrons caused by the rapid spatial variation of the exchange potential results in an out-of-plane torque that increases rapidly with decreasing DW length. Read More

We have acquired Hubble Space Telescope (HST) and Very Large Telescope near-infrared spectra and images of supernova (SN) Refsdal after its discovery as an Einstein cross in Fall 2014. The HST light curve of SN Refsdal matches the distinctive, slowly rising light curves of SN 1987A-like supernovae (SNe), and we find strong evidence for a broad H-alpha P-Cygni profile in the HST grism spectrum at the redshift (z = 1.49) of the spiral host galaxy. Read More

The spin Hall angle (SHA) is a measure of the efficiency with which a transverse spin current is generated from a charge current by the spin-orbit coupling and disorder in the spin Hall effect (SHE). In a study of the SHE for a Pt$|$Py (Py=Ni$_{80}$Fe$_{20}$) bilayer using a first-principles scattering approach, we find a SHA that increases monotonically with temperature and is proportional to the resistivity for bulk Pt. By decomposing the room temperature SHE and inverse SHE currents into bulk and interface terms, we discover a giant interface SHA that dominates the total inverse SHE current with potentially major consequences for applications. Read More

Henkin, Monk and Tarski gave a compositional semantics for first-order predicate logic. We extend this work by including function symbols in the language and by giving the denotation of the atomic formula as a composition of the denotations of its predicate symbol and of its tuple of arguments. In addition we give the denotation of a term as a composition of the denotations of its function symbol and of its tuple of arguments. Read More

We present the first year of Hubble Space Telescope imaging of the unique supernova (SN) 'Refsdal', a gravitationally lensed SN at z=1.488$\pm$0.001 with multiple images behind the galaxy cluster MACS J1149. Read More

In Hubble Space Telescope (HST) imaging taken on 10 November 2014, four images of supernova (SN) "Refsdal" (redshift z=1.49) appeared in an Einstein-cross--like configuration (images S1-S4) around an early-type galaxy in the cluster MACS J1149.5+2223 (z=0. Read More

Supernova "Refsdal," multiply imaged by cluster MACSJ1149.5+2223, represents a rare opportunity to make a true blind test of model predictions in extragalactic astronomy, on a time scale that is short compared to a human lifetime. In order to take advantage of this event, we produced seven gravitational lens models with five independent methods, based on Hubble Space Telescope (HST) Hubble Frontier Field images, along with extensive spectroscopic follow-up observations by HST, the Very Large and the Keck Telescopes. Read More

2015Sep
Affiliations: 1UC Berkeley, 2Steward, 3Lawrence Livermore, 4Steward, 5UC Davis, 6NASA Goddard/UMD, 7LSU, 8NASA Goddard, 9UC Berkeley, 10University of Cincinnati, 11UC Berkeley, 12UC Berkeley, 13Caltech, 14IPAC

SN 2006gy was the most luminous SN ever observed at the time of its discovery and the first of the newly defined class of superluminous supernovae (SLSNe). The extraordinary energetics of SN 2006gy and all SLSNe (>10^51 erg) require either atypically large explosion energies (e.g. Read More

SLAM has matured significantly over the past few years, and is beginning to appear in serious commercial products. While new SLAM systems are being proposed at every conference, evaluation is often restricted to qualitative visualizations or accuracy estimation against a ground truth. This is due to the lack of benchmarking methodologies which can holistically and quantitatively evaluate these systems. Read More

This is the fourth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here, we use measurements of weak gravitational lensing from the Weighing the Giants project to calibrate Chandra X-ray measurements of total mass that rely on the assumption of hydrostatic equilibrium. This comparison of X-ray and lensing masses provides a measurement of the combined bias of X-ray hydrostatic masses due to both astrophysical and instrumental sources. Read More

We give an overview of the Grism Lens Amplified Survey from Space (GLASS), a large Hubble Space Telescope program aimed at obtaining grism spectroscopy of the fields of ten massive clusters of galaxies at redshift z=0.308-0.686, including the Hubble Frontier Fields (HFF). Read More

We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calculated from first principles. For Fe, the agreement with experiment is limited by how well the magnetization (of itinerant ferromagnets) can be calculated as a function of temperature. Read More

We present deep, 170 ks, Chandra X-ray observations of Abell 2219 (z=0.23) one of the hottest and most X-ray luminous clusters known, and which is experiencing a major merger event. We discover a 'horseshoe' of high temperature gas surrounding the ram-pressure-stripped, bright, hot, X-ray cores. Read More

Thread-level parallelism in irregular applications with mutable data dependencies presents challenges because the underlying data is extensively modified during execution of the algorithm and a high degree of parallelism must be realized while keeping the code race-free. In this article we describe a methodology for exploiting thread parallelism for a class of graph-mutating worklist algorithms, which guarantees safe parallel execution via processing in rounds of independent sets and using a deferred update strategy to commit changes in the underlying data structures. Scalability is assisted by atomic fetch-and-add operations to create worklists and work-stealing to balance the shared-memory workload. Read More

Irregular computations on unstructured data are an important class of problems for parallel programming. Graph coloring is often an important preprocessing step, e.g. Read More

In this paper we present a parallel for-loop scheduler which is based on work-stealing principles but runs under a completely cooperative scheme. POSIX signals are used by idle threads to interrupt left-behind workers, which in turn decide what portion of their workload can be given to the requester. We call this scheme Interrupt-Driven Work-Sharing (IDWS). Read More

Firedrake is a new tool for automating the numerical solution of partial differential equations. Firedrake adopts the domain-specific language for the finite element method of the FEniCS project, but with a pure Python runtime-only implementation centred on the composition of several existing and new abstractions for particular aspects of scientific computing. The result is a more complete separation of concerns which eases the incorporation of separate contributions from computer scientists, numerical analysts and application specialists. Read More

We present a time series of the highest resolution spectra yet published for the nearby Type Ia supernova (SN) 2014J in M82. They were obtained at 11 epochs over 33 days around peak brightness with the Levy Spectrograph (resolution R~110,000) on the 2.4m Automated Planet Finder telescope at Lick Observatory. Read More

2014Nov
Affiliations: 1Dark Cosmology Centre, 2Dark Cosmology Centre, 3MPA, 4KICP Chicago, 5KIPAC Stanford/SLAC, 6Bonn, 7UC Berkeley, 8Dark Cosmology Centre, 9KIPAC Stanford/SLAC

The abundance of massive galaxy clusters is a powerful probe of departures from General Relativity (GR) on cosmic scales. Despite current stringent constraints placed by stellar and galactic tests, on larger scales alternative theories of gravity such as $f(R)$ can still work as effective theories. Here we present constraints on two popular models of $f(R)$, Hu-Sawicki and "designer", derived from a fully self-consistent analysis of current samples of X-ray selected clusters and accounting for all the covariances between cosmological and astrophysical parameters. Read More

Potential steps exceeding 1 eV are regularly formed at metal|insulator interfaces, even when the interaction between the materials at the interface is weak physisorption. From first-principles calculations on metal|h-BN interfaces we show that these potential steps are only indirectly sensitive to the interface bonding through the dependence of the binding energy curves on the van der Waals interaction. Exchange repulsion forms the main contribution to the interface potential step in the weakly interacting regime, which we show with a simple model based upon a symmetrized product of metal and h-BN wave functions. Read More

2014Nov
Affiliations: 1UCB, 2JHU, 3UCLA, 4Illinois, 5STScI, 6UCSB, 7Caltech, 8UCLA, 9STScI, 10NYU/AMNH, 11UCB, 12Rutgers, 13JHU/STScI, 14UCD, 15Arizona, 16Chicago, 17UCLA, 18DARK/Stanford, 19Melbourne, 20DARK, 21IAP, 22INAF-OAR, 23Caltech, 24LCOGT/UC Santa Barbara, 25UCLA, 26STScI, 27Carnegie Obs., 28Rutgers, 29GSFC/UMD, 30UCB, 31UCB/ANU

In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. We report the discovery of such a system. In Hubble Space Telescope imaging, we have found four images of a single supernova forming an Einstein cross configuration around a redshift z=0. Read More

Real-time dense computer vision and SLAM offer great potential for a new level of scene modelling, tracking and real environmental interaction for many types of robot, but their high computational requirements mean that use on mass market embedded platforms is challenging. Meanwhile, trends in low-cost, low-power processing are towards massive parallelism and heterogeneity, making it difficult for robotics and vision researchers to implement their algorithms in a performance-portable way. In this paper we introduce SLAMBench, a publicly-available software framework which represents a starting point for quantitative, comparable and validatable experimental research to investigate trade-offs in performance, accuracy and energy consumption of a dense RGB-D SLAM system. Read More

The luminosities of Type Ia supernovae (SNe), the thermonuclear explosions of white-dwarf stars, vary systematically with their intrinsic color and the rate at which they fade. From images taken with the Galaxy Evolution Explorer (GALEX), we identified SNe Ia that erupted in environments that have high ultraviolet surface brightness and star-formation surface density. When we apply a steep model extinction law, we calibrate these SNe using their broadband optical light curves to within ~0. Read More

We use density functional theory calculations to show that the LaAlO3|SrTiO3 interface between insulating perovskite oxides is borderline in satisfying the Stoner criterion for itinerant ferromagnetism and explore other oxide combinations with a view to satisfying it more amply. The larger lattice parameter of an LaScO3|BaTiO3 interface is found to be less favorable than the greater interface distortion of LaAlO3|CaTiO3. Compared to LaAlO3|SrTiO3, the latter is predicted to exhibit robust magnetism with a larger saturation moment and a higher Curie temperature. Read More

A growing subset of Type Ia supernovae (SNe Ia) show evidence for unexpected interaction with a dense circumstellar medium (SNe Ia-CSM). The precise nature of the progenitor, however, remains debated owing to spectral ambiguities arising from a strong contribution from the CSM interaction. Late-time spectra offer potential insight if the post-shock cold, dense shell becomes sufficiently thin and/or the ejecta begin to cross the reverse shock. Read More

The nearby Type Ia supernovae (SNe Ia) 2011fe and 2011by had nearly identical photospheric phase optical spectra, light-curve widths, and photometric colours, but at peak brightness SN 2011by reached a fainter absolute magnitude in all optical bands and exhibited lower flux in the near-ultraviolet (NUV). Based on those data, Foley & Kirshner (2013) argue that the progenitors of SNe 2011by and 2011fe were supersolar and subsolar, respectively, and that SN 2011fe generated 1.7 times the amount of 56Ni as SN 2011by. Read More

2014Jul
Affiliations: 1KICP Chicago, 2KIPAC Stanford/SLAC, 3KIPAC Stanford/SLAC, 4Bonn, 5UC Berkeley, 6KIPAC Stanford/SLAC, 7DARK Cosmology Centre, 8Heidelberg, 9IGC Penn. State, 10KIPAC Stanford/SLAC, 11KIPAC Stanford/SLAC, 12KIPAC Stanford/SLAC, 13DARK Cosmology Centre, 14IfA Hawaii, 15IfA Hawaii, 16IGC Penn. State, 17KIPAC Stanford/SLAC

We employ robust weak gravitational lensing measurements to improve cosmological constraints from measurements of the galaxy cluster mass function and its evolution, using X-ray selected clusters detected in the ROSAT All-Sky Survey. Our lensing analysis constrains the absolute mass scale of such clusters at the 8 per cent level, including both statistical and systematic uncertainties. Combining it with the survey data and X-ray follow-up observations, we find a tight constraint on a combination of the mean matter density and late-time normalization of the matter power spectrum, $\sigma_8(\Omega_m/0. Read More

The numerical solution of partial differential equations using the finite element method is one of the key applications of high performance computing. Local assembly is its characteristic operation. This entails the execution of a problem-specific kernel to numerically evaluate an integral for each element in the discretized problem domain. Read More