Results for "Arjen van Elteren"

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The signatures of the parental cluster on field planetary systemsNov 03 2017Nov 23 2017Due to the high stellar densities in young clusters, planetary systems formed in these environments are likely to have experienced perturbations from encounters with other stars. We carry out direct $N$-body simulations of multi-planet systems in star ... More
The consequences of a nearby supernova on the early Solar SystemFeb 12 2018If the Sun was born in a relatively compact open cluster (half-mass radius ~3pc) with ~10^3 stars, it is quite likely that a massive (>10MSun) star was nearby when it exploded in a supernova. The repercussions of a supernova can be rather profound, and ... More
The influence of dense gas rings on the dynamics of a stellar disk in the Galactic centerDec 08 2015The Galactic center hosts several hundred early-type stars, about 20% of which lie in the so-called clockwise disk, while the remaining 80% do not belong to any disks. The circumnuclear ring (CNR), a ring of molecular gas that orbits the supermassive ... More
Cosmogenic photons strongly constrain UHECR source modelsSep 12 2016With the newest version of our Monte Carlo code for ultra-high-energy cosmic ray (UHECR) propagation, CRPropa 3, the flux of neutrinos and photons due to interactions of UHECRs with extragalactic background light can be predicted. Together with the recently ... More
Simulations of Dense Stellar Systems with the AMUSE Software ToolkitNov 16 2011We describe AMUSE, the Astrophysical Multipurpose Software Environment, a programming framework designed to manage multi-scale, multi-physics simulations in a hierarchical, extensible, and internally consistent way. Constructed as a collection of individual ... More
Multi-physics simulations using a hierarchical interchangeable software interfaceOct 12 2011We introduce a general-purpose framework for interconnecting scientific simulation programs using a homogeneous, unified software interface. Our framework is intrinsically parallel, and conveniently separates all components in memory. It performs unit ... More
Multi-physics simulations using a hierarchical interchangeable software interfaceApr 25 2012Sep 17 2012We introduce a general-purpose framework for interconnecting scientific simulation programs using a homogeneous, unified interface. Our framework is intrinsically parallel, and conveniently separates all component numerical modules in memory. This strict ... More
The similar stellar populations of quiescent spiral and elliptical galaxiesSep 25 2011Jul 18 2012We compare the stellar population properties in the central regions of visually classified non-starforming spiral and elliptical galaxies from Galaxy Zoo and SDSS DR7. The galaxies lie in the redshift range $0.04<z<0.1$ and have stellar masses larger ... More
CRPropa 2.0 -- a Public Framework for Propagating High Energy Nuclei, Secondary Gamma Rays and NeutrinosJun 14 2012Version 2.0 of CRPropa is public software to model the extra-galactic propagation of ultra-high energy nuclei of atomic number Z<26 through structured magnetic fields and ambient photon backgrounds taking into account all relevant particle interactions. ... More
A New Method for Wide-Field Near-IR Imaging with the Hubble Space TelescopeMar 01 2016We present a new technique for wide and shallow observations using the near-infrared channel of Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). Wide-field near-IR surveys with HST are generally inefficient, as guide star acquisitions make ... More
The dynamics of disappearing pulses in a singularly perturbed reaction-diffusion system with parameters that vary in time and spaceFeb 08 2018We consider the evolution of multi-pulse patterns in an extended Klausmeier equation with parameters that change in time and/or space. We formally show that the full PDE dynamics of a $N$-pulse configuration can be reduced to a $N$-dimensional dynamical ... More
Multi-scale and multi-domain computational astrophysicsFeb 19 2014Astronomical phenomena are governed by processes on all spatial and temporal scales, ranging from days to the age of the Universe (13.8,Gyr) as well as from km size up to the size of the Universe. This enormous range in scales is contrived, but as long ... More
Not In Our Backyard: Spectroscopic Support for the CLASH z=11 Candidate MACS0647-JDFeb 19 2015Feb 22 2015We report on our first set of spectroscopic Hubble Space Telescope observations of the z~11 candidate galaxy strongly lensed by the MACSJ0647.7+7015 galaxy cluster. The three lensed images are faint and we show that these early slitless grism observations ... More
Determining neutrino absorption spectra at Ultra-High EnergiesJan 22 2008Apr 16 2008A very efficient method to measure the flux of Ultra-high energy (UHE) neutrinos is through the detection of radio waves which are emitted by the particle shower in the lunar regolith. The highest acceptance is reached for radio waves in the frequency ... More
PeV Neutrinos from Ultra-High-Energy Cosmic RaysJul 24 2014We investigate the possibility that the recently detected TeV-PeV neutrino events by IceCube can originate from extragalactic ultra-high-energy cosmic ray interactions with the cosmic microwave background or the UV/optical/IR background. This is done ... More
Stellar Dynamics and Star-Formation Histories of z $\sim$ 1 Radio-loud GalaxiesAug 28 2017We investigate the stellar kinematics and stellar populations of 58 radio-loud galaxies of intermediate luminosities (L$_{3 GHz}$ $>$ 10$^{23}$ W Hz$^{-1}$ ) at 0.6 < z < 1. This sample is constructed by cross-matching galaxies from the deep VLT/VIMOS ... More
The Spatial Extent and Distribution of Star Formation in 3D-HST Mergers at z~1.5Mar 14 2013We present an analysis of the spatial distribution of star formation in a sample of 60 visually identified galaxy merger candidates at z>1. Our sample, drawn from the 3D-HST survey, is flux-limited and was selected to have high star formation rates based ... More
On the importance of using appropriate spectral models to derive physical properties of galaxies at 0.7<z<2.8Nov 20 2014Interpreting observations of distant galaxies in terms of constraints on physical parameters - such as stellar mass, star-formation rate (SFR) and dust optical depth - requires spectral synthesis modelling. We analyse the reliability of these physical ... More
An Integrated Research Infrastructure for Validating Cyber-Physical Energy SystemsOct 06 2017Renewables are key enablers in the plight to reduce greenhouse gas emissions and cope with anthropogenic global warming. The intermittent nature and limited storage capabilities of renewables culminate in new challenges that power system operators have ... More
Runtime Optimizations for Prediction with Tree-Based ModelsDec 11 2012Apr 26 2013Tree-based models have proven to be an effective solution for web ranking as well as other problems in diverse domains. This paper focuses on optimizing the runtime performance of applying such models to make predictions, given an already-trained model. ... More
CLASH: Extreme Emission Line Galaxies and Their Implication on Selection of High-Redshift GalaxiesDec 26 2014We utilize the CLASH (Cluster Lensing And Supernova survey with Hubble) observations of 25 clusters to search for extreme emission-line galaxies (EELGs). The selections are carried out in two central bands: F105W (Y105) and F125W (J125), as the flux of ... More
Ultra-deep Ks-band Imaging of the Hubble Frontier FieldsJun 23 2016We present an overview of the "KIFF" project, which provides ultra-deep Ks-band imaging of all six of the Hubble Frontier Fields clusters Abell 2744, MACS-0416, Abell S1063, Abell 370, MACS-0717 and MACS-1149. All of these fields have recently been observed ... More
3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar MassesMar 14 2014Jul 18 2014The 3D-HST and CANDELS programs have provided WFC3 and ACS spectroscopy and photometry over ~900 square arcminutes in five fields: AEGIS, COSMOS, GOODS-North, GOODS-South, and the UKIDSS UDS field. All these fields have a wealth of publicly available ... More
The Astrophysical Multipurpose Software EnvironmentJul 11 2013We present the open source Astrophysical Multi-purpose Software Environment (AMUSE, www.amusecode.org), a component library for performing astrophysical simulations involving different physical domains and scales. It couples existing codes within a Python ... More
ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular gas reservoirs in high-redshift galaxiesJul 22 2016Sep 12 2016We study the molecular gas properties of high-$z$ galaxies observed in the ALMA Spectroscopic Survey (ASPECS) that targets a $\sim1$ arcmin$^2$ region in the Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing molecular gas) in the 3mm ... More
Spatially Resolved Stellar Kinematics of Field Early-Type Galaxies at z=1: Evolution of the Rotation RateApr 26 2008Jun 20 2008We use the spatial information of our previously published VLT/FORS2 absorption line spectroscopy to measure mean stellar velocity and velocity dispersion profiles of 25 field early-type galaxies at a median redshift z=0.97 (full range 0.6<z<1.2). This ... More
Generalization of the event-based Carnevale-Hines integration scheme for integrate-and-fire modelsMay 12 2008An event-based integration scheme for an integrate-and-fire neuron model with exponentially decaying excitatory synaptic currents and double exponential inhibitory synaptic currents has recently been introduced by Carnevale and Hines. This integration ... More
Galaxy Structure and Mode of Star Formation in the SFR-Mass Plane from z ~ 2.5 to z ~ 0.1Jul 01 2011Oct 11 2011We analyze the dependence of galaxy structure (size and Sersic index) and mode of star formation (\Sigma_SFR and SFR_IR/SFR_UV) on the position of galaxies in the SFR versus Mass diagram. Our sample comprises roughly 640000 galaxies at z~0.1, 130000 galaxies ... More
The Nature of Massive Transition Galaxies in CANDELS, GAMA, and Cosmological SimulationsNov 11 2016It is common practice to speak of a "green valley" that hosts galaxies whose colors are intermediate relative to those in the "blue cloud" and the "red sequence." In this study, we raise several questions about how galaxies might transition between the ... More
Checking the Quality of Clinical Guidelines using Automated Reasoning ToolsJun 02 2008Requirements about the quality of clinical guidelines can be represented by schemata borrowed from the theory of abductive diagnosis, using temporal logic to model the time-oriented aspects expressed in a guideline. Previously, we have shown that these ... More
A simple rule for axon outgrowth and synaptic competition generates realistic connection lengths and filling fractionsJun 03 2009Neural connectivity at the cellular and mesoscopic level appears very specific and is presumed to arise from highly specific developmental mechanisms. However, there are general shared features of connectivity in systems as different as the networks formed ... More
ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey DescriptionJul 22 2016We present the rationale for and the observational description of ASPECS: The ALMA SPECtroscopic Survey in the Hubble Ultra-Deep Field (UDF), the cosmological deep field that has the deepest multi-wavelength data available. Our overarching goal is to ... More
PeV neutrinos from the propagation of ultra-high energy cosmic raysSep 18 2012Jan 23 2013We discuss the possibility that the PeV neutrinos recently observed by IceCube are produced by the interactions of extragalactic cosmic rays during their propagation through the radiation backgrounds. We show that the fluxes resulting from the decays ... More
ALMA spectroscopic survey in the Hubble Ultra Deep Field: CO luminosity functions and the evolution of the cosmic density of molecular gasJul 22 2016Sep 12 2016In this paper we use ASPECS, the ALMA Spectroscopic Survey in the {\em Hubble} Ultra Deep Field (UDF) in band 3 and band 6, to place blind constraints on the CO luminosity function and the evolution of the cosmic molecular gas density as a function of ... More
The Relation between Galaxy Structure and Spectral Type: Implications for the Buildup of the Quiescent Galaxy Population at 0.5<z<2.0Jan 11 2016We present the relation between galaxy structure and spectral type, using a K-selected galaxy sample at 0.5<z<2.0. Based on similarities between the UV-to-NIR spectral energy distributions, we classify galaxies into 32 spectral types. The different types ... More
GOODS-Herschel and CANDELS: The Morphologies of Ultraluminous Infrared Galaxies at z~2Oct 18 2011Aug 14 2012Using deep 100-160 micron observations in GOODS-S from the GOODS-H survey, combined with HST/WFC3 NIR imaging from CANDELS, we present the first morphological analysis of a complete, FIR selected sample of 52 ULIRGs at z~2. We also make use of a comparison ... More
CANDELS: Constraining the AGN-Merger Connection with Host Morphologies at z~2Sep 12 2011Using HST/WFC3 imaging taken as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), we examine the role that major galaxy mergers play in triggering active galactic nuclei (AGN) activity at z~2. Our sample consists of ... More
The Detection of a Red Sequence of Massive Field Galaxies at z~2.3 and its Evolution to z~0Apr 28 2008The existence of massive galaxies with strongly suppressed star formation at z~2.3, identified in a previous paper, suggests that a red sequence may already be in place beyond z=2. In order to test this hypothesis, we study the rest-frame U-B color distribution ... More
On the Masses of Galaxies in the Local UniverseSep 08 2010We compare estimates of stellar mass, Mstar, and dynamical mass,Mdyn,for a sample of galaxies from the Sloan Digital Sky Survey (SDSS). We assume dynamical homology (i.e., Mdyn = dispersion**2 * Reff, and we find a tight but strongly non-linear relation: ... More
The Physical Origins of The Morphology-Density Relation: Evidence for Gas Stripping from the SDSSApr 02 2010Apr 26 2010We provide a physical interpretation and explanation of the morphology-density relation for galaxies, drawing on stellar masses, star formation rates, axis ratios and group halo masses from the Sloan Digital Sky Survey. We first re-cast the classical ... More
A constant limiting mass scale for flat early-type galaxies from z=1 to z=0: density evolves but shapes do notAug 30 2011Sep 01 2011We measure the evolution in the intrinsic shape distribution of early-type galaxies from z~1 to z~0 by analyzing their projected axis-ratio distributions. We extract a low-redshift sample (0.04 < z < 0.08) of early-type galaxies with very low star-formation ... More
Spontaneous Charging and Crystallization of Water Droplets in OilJul 29 2008Jul 31 2008We study the spontaneous charging and the crystallization of spherical micron-sized water-droplets dispersed in oil by numerically solving, within a Poisson-Boltzmann theory in the geometry of a spherical cell, for the density profiles of the cations ... More
M/L and Color Evolution for A Deep Sample of M* Cluster Galaxies at z~1: The Formation Epoch and the Tilt of the Fundamental PlaneSep 22 2010Oct 08 2010We have measured velocity dispersions for a sample of 36 galaxies with J < 21.2 or Mr < -20.6 mag in MS1054-03, a massive cluster of galaxies at z = 0.83. Our data are of uniformly high quality down to our selection limit, our 16-hour exposures typically ... More
Stellar Masses and SFRs for 1M Galaxies from SDSS and WISEJun 01 2015We combine SDSS and WISE photometry for the full SDSS spectroscopic galaxy sample, creating SEDs that cover lambda=0.4-22 micron for an unprecedented large and comprehensive sample of 858,365 present-epoch galaxies. Using MAGPHYS we then model simultaneously ... More
Effects of uncertainties in simulations of extragalactic UHECR propagation, using CRPropa and SimPropAug 07 2015Dec 13 2015The results of simulations of the extragalactic propagation of ultra-high energy cosmic rays (UHECRs) have intrinsic uncertainties due to poorly known physical quantities and approximations used in the codes. We quantify the uncertainties in the simulated ... More
Comparing Dynamical and Photometric Mass Estimates of Low- and High-Redshift Galaxies: Random and Systematic UncertaintiesJul 28 2006We determine the importance of redshift-dependent systematic effects in the determination of stellar masses from broad band spectral energy distributions (SEDs), using high quality kinematic and photometric data of early-type galaxies at z~1 and z~0. ... More
The Pair Fraction of Massive Galaxies at 0 < z < 3Sep 13 2011Using a mass-selected ($M_{\star} \ge 10^{11} M_{\odot}$) sample of 198 galaxies at 0 < z < 3.0 with HST/NICMOS $H_{160}$-band images from the COSMOS survey, we find evidence for the evolution of the pair fraction above z ~ 2, an epoch in which massive ... More
Major Merging: The Way to Make a Massive, Passive GalaxyOct 21 2009Nov 10 2009We analyze the projected axial ratio distribution, p(b/a), of galaxies that were spectroscopically selected from the Sloan Digital Sky Survey (DR6) to have low star-formation rates. For these quiescent galaxies we find a rather abrupt change in p(b/a) ... More
On the Size and Comoving Mass Density Evolution of Early-Type GalaxiesMar 27 2009Apr 24 2009We present a simple, empirically motivated model that simultaneously predicts the evolution of the mean size and the comoving mass density of massive early-type galaxies from z=2 to the present. First we demonstrate that some size evolution of the population ... More
On the Dearth of Compact, Massive, Red Sequence Galaxies in the Local UniverseJul 27 2009Using data from the Sloan Digital Sky Survey (SDSS; data release 7), we have conducted a search for local analogs to the extremely compact, massive, quiescent galaxies that have been identified at z > 2. We show that incompleteness is a concern for such ... More
The UVJ Selection of Quiescent and Star Forming Galaxies: Separating Early and Late-Type Galaxies and Isolating Edge-on SpiralsJul 15 2011We utilize for the first time HST ACS imaging to examine the structural properties of galaxies in the rest-frame U-V versus V-J diagram (i.e., the UVJ diagram) using a sample at 0.6<z<0.9 that reaches a low stellar mass limit (log M/Msun>10.25). The use ... More
Recent Structural Evolution of Early-Type Galaxies: Size Growth from z=1 to z=0Aug 01 2008Oct 02 2008Strong size and internal density evolution of early-type galaxies between z~2 and the present has been reported by several authors. Here we analyze samples of nearby and distant (z~1) galaxies with dynamically measured masses in order to confirm the previous, ... More
A Wide-Field Study of the z~0.8 Cluster RX J0152.7-1357: the Role of Environment in the Formation of the Red-SequenceDec 10 2008Jan 27 2009[ABRIDGED] We present the first results from the largest spectroscopic survey to date of an intermediate redshift galaxy cluster, the z=0.834 cluster RX J0152.7-1357. We use the colors of galaxies, assembled from a D~12 Mpc region centered on the cluster, ... More
Shape Evolution of Massive Early-Type Galaxies: Confirmation of Increased Disk Prevalence at z>1Nov 09 2012We use high-resolution K-band VLT/HAWK-I imaging over 0.25 square degrees to study the structural evolution of massive early-type galaxies since z~1. Mass-selected samples, complete down to log(M/M_sun)~10.7 such that `typical' L* galaxies are included ... More
An Over-Massive Black Hole in the Compact Lenticular Galaxy NGC1277Nov 27 2012All massive galaxies likely have supermassive black holes at their centers, and the masses of the black holes are known to correlate with properties of the host galaxy bulge component. Several explanations have been proposed for the existence of these ... More
Weakly nonlocal irreversible thermodynamics - the Guyer-Krumhansl and the Cahn-Hilliard equationsJun 27 2001Oct 18 2001Examples of irreversible thermodynamic theory of nonlocal phenomena are given, based on generalized entropy current. Thermodynamic currents and forces are identified to derive the Guyer-Krumhansl and Cahn-Hilliard equations. In the latter case Gurtin's ... More
Weakly nonlocal irreversible thermodynamics - the Ginzburg-Landau equationNov 16 2001Dec 12 2001The variational approach to weakly nonlocal thermodynamic theories is critically revisited in the light of modern nonequilibrium thermodynamics. The example of Ginzburg-Landau equation is investigated in detail.
A number theoretic question arising in the geometry of plane curves and in billiard dynamicsMar 25 2011We prove that if $\rho\neq1/2$ is a rational number between zero and one, then there is no integer $n>1$ such that $$ n\tan(\pi\rho)=\tan(n\pi\rho). $$ This has interpretations both in the theory of bicycle curves and that of mathematical billiards.
A simple SVD algorithm for finding hidden partitionsApr 15 2014Finding a hidden partition in a random environment is a general and important problem, which contains as subproblems many famous questions, such as finding a hidden clique, finding a hidden coloring, finding a hidden bipartition etc. In this paper, we ... More
Central limit theorems for random polytopes in a smooth convex setMar 24 2005Let $K$ be a smooth convex set with volume one in $\BBR^d$. Choose $n$ random points in $K$ independently according to the uniform distribution. The convex hull of these points, denoted by $K_n$, is called a {\it random polytope}. We prove that several ... More
Emergence of steady and oscillatory localized structures in a phytoplankton-nutrient modelSep 16 2010Aug 26 2011Co-limitation of marine phytoplankton growth by light and nutrient, both of which are essential for phytoplankton, leads to complex dynamic behavior and a wide array of coherent patterns. The building blocks of this array can be considered to be deep ... More
Sum-product estimates via directed expandersMay 04 2007Let $\F_q$ be a finite field of order $q$ and $P$ be a polynomial in $\F_q[x_1, x_2]$. For a set $A \subset \F_q$, define $P(A):=\{P(x_1, x_2) | x_i \in A \}$. Using certain constructions of expanders, we characterize all polynomials $P$ for which the ... More
A structural approach to subset-sum problemsApr 20 2008We discuss a structural approach to subset-sum problems in additive combinatorics. The core of this approach are Freiman-type structural theorems, many of which will be presented through the paper. These results have applications in various areas, such ... More
Singular vectors under random perturbationApr 12 2010Computing the first few singular vectors of a large matrix is a problem that frequently comes up in statistics and numerical analysis. Given the presence of noise, exact calculation is hard to achieve, and the following problem is of importance: \vskip2mm ... More
A Parallel-pulling Protocol for Free-Energy EvaluationMay 24 2011Feb 14 2012Jarzynski's equality (JE) allows us to compute free energy differences from distributions of work. In molecular dynamics simulations, the traditional way of constructing work distributions is to perform as many pulling simulations as possible. But reliable ... More
The Luminosity-Size and Mass-Size Relations of Galaxies out to z~3Jul 01 2003Dec 16 2003The luminosity-size and stellar mass-size distributions of galaxies out to z~3 is presented. We use very deep near-infrared images of the Hubble Deep Field South in the J_s, H, and K_s bands, taken as part FIRES at the VLT, to follow the evolution of ... More
The Rest-Frame Optical Luminosity Density, Color, and Stellar Mass Density of the Universe from z=0 to z=3Jul 08 2003Sep 09 2003We present the evolution of the rest-frame optical luminosity density, of the integrated rest-frame optical color, and of the stellar mass density for a sample of Ks-band selected galaxies in the HDF-S. We derived the luminosity density in the rest-frame ... More
A Significant Population of Red, Near-IR Selected High Redshift GalaxiesMar 07 2003We use very deep near-infrared photometry of the Hubble Deep Field South taken with ISAAC/VLT to identify a population of high redshift galaxies with rest- frame optical colors similar to those of nearby galaxies. The galaxies are chosen by their infrared ... More
The merger-driven evolution of massive galaxiesFeb 22 2010Jun 29 2010We explore the rate and impact of galaxy mergers on the massive galaxy population using the amplitude of the two-point correlation function on small scales for M > 5e10 M_sun galaxies from the COSMOS and COMBO-17 surveys. Using a pair fraction derived ... More
CRPropa 3 - a Public Astrophysical Simulation Framework for Propagating Extraterrestrial Ultra-High Energy ParticlesMar 23 2016May 24 2016We present the simulation framework CRPropa version 3 designed for efficient development of astrophysical predictions for ultra-high energy particles. Users can assemble modules of the most relevant propagation effects in galactic and extragalactic space, ... More
Weakly nonlocal continuum physics - the Ginzburg-Landau equationOct 18 2002May 13 2003Some peculiarities of the exploitation of the entropy inequality in case of weakly nonlocal continuum theories are investigated and refined. As an example it is shown that the proper application of the Liu procedure leads to the Ginzburg-Landau equation ... More
Weakly nonlocal continuum theories of granular media: restrictions from the Second LawOct 22 2003Nov 07 2003The classical continuum mechanical model of granular media of rational thermodynamics results in a Coulomb-Mohr type equilibrium stress-strain relation. The proof is based on a two component material model introducing a scalar internal variable. Here ... More
Weakly nonlocal irreversible thermodynamicsDec 12 2001Jan 10 2003Weakly nonlocal thermodynamic theories are critically revisited. A relocalized, irreversible thermodynamic theory of nonlocal phenomena is given, based on a modified form of the entropy current and new kind of internal variables, the so called current ... More
The Majority of Compact Massive Galaxies at z~2 are Disk DominatedJan 12 2011Mar 10 2011We investigate the stellar structure of massive, quiescent galaxies at z~2, based on Hubble Space Telescope/WFC3 imaging from the Early Release Science program. Our sample of 14 galaxies has stellar masses of M* > 10^{10.8} Msol and photometric redshifts ... More
Spectroscopic Confirmation of a Substantial Population of Luminous Red Galaxies at Redshifts z>2Mar 07 2003We confirm spectroscopically the existence of a population of galaxies at z>~2 with rest-frame optical colors similar to normal nearby galaxies. The galaxies were identified by their red near-infrared colors in deep images obtained with ISAAC on the Very ... More
Morphologies of low-redshift AGN host galaxies: what role does AGN luminosity play?Mar 08 2013Mergers of galaxies have been suspected to be a major trigger of AGN activity for many years. However, when compared to carefully matched control samples, AGN host galaxies often show no enhanced signs of interaction. A common explanation for this lack ... More
The Number Density Evolution of Extreme Emission Line Galaxies in 3D-HST: Results from a Novel Automated Line Search Technique for Slitless SpectroscopyAug 04 2016The multiplexing capability of slitless spectroscopy is a powerful asset in creating large spectroscopic datasets, but issues such as spectral confusion make the interpretation of the data challenging. Here we present a new method to search for emission ... More
CRPropa 3.0 - a Public Framework for Propagating UHE Cosmic Rays through Galactic and Extragalactic SpaceJul 10 2013The interpretation of experimental data of ultra-high energy cosmic rays (UHECRs) above 10^17 eV is still under controversial debate. The development and improvement of numerical tools to propagate UHECRs in galactic and extragalactic space is a crucial ... More
Cosmic ray propagation with CRPropa 3Oct 20 2014Solving the question of the origin of ultra-high energy cosmic rays (UHECRs) requires the development of detailed simulation tools in order to interpret the experimental data and draw conclusions on the UHECR universe. CRPropa is a public Monte Carlo ... More
Measuring the Average Evolution of Luminous Galaxies at z<3: The Rest-frame Optical Luminosity Density, Spectral Energy Distribution, and Stellar Mass DensityJun 21 2006(Abridged) We present the evolution of the volume averaged properties of the rest-frame optically luminous galaxy population to z~3, determined from four disjoint deep fields with optical to near-infrared wavelength coverage. We select galaxies above ... More
Accurate energy-size dependence of excitonic transitions in semiconductor nanocrystals and nanoplatelets using a phase jump approachNov 21 2013Accurate energy-size dependence of excitonic transitions in semiconductor nanocrystals in the strong confinement regime using classical theoretical approaches such as effective mass approximation, tight binding, or empirical pseudo-potential is difficult. ... More
An Algebraic Framework for Discrete Tomography: Revealing the Structure of DependenciesJun 03 2009Jul 30 2009Discrete tomography is concerned with the reconstruction of images that are defined on a discrete set of lattice points from their projections in several directions. The range of values that can be assigned to each lattice point is typically a small discrete ... More
Optical probes of electron correlations in solidsJul 21 2008Classically the interaction between light and matter is given by the Maxwell relations. These are briefly reviewed and will be used as a basis to discuss several techniques that are used in optical spectroscopy. We then discuss the quantum mechanical ... More
Limit to manipulation of qubits due to spontaneous symmetry breakingJun 07 2006We consider a two-spin qubit that is subject to the orderparameter field of a symmetry broken manipulation device. It is shown that the thin spectrum of the manipulation device limits the coherence of the qubit.
Orbital-Peierls State in NaTiSi2O6Dec 22 2005Dec 23 2005Does the quasi one-dimensional titanium pyroxene NaTiSi2O6 exhibit the novel {\it orbital-Peierls} state? We calculate its groundstate properties by three methods: Monte Carlo simulations, a spin-orbital decoupling scheme and a mapping onto a classical ... More
Convection in rotating annuli: Ginzburg-Landau equations with tunable coefficientsSep 12 1996The coefficients of the complex Ginzburg-Landau equations that describe weakly nonlinear convection in a large rotating annulus are calculated for a range of Prandtl numbers $\sigma$. For fluids with $\sigma \approx 0.15$, we show that the rotation rate ... More
Theory of indirect resonant inelastic X-ray scatteringNov 19 2003We express the cross section for indirect resonant inelastic X-ray scattering in terms of an intrinsic dynamic correlation function of the system that is studied with this technique. The cross section is a linear combination of the charge response function ... More
Monodromy calculatons of fourth order equations of Calabi-Yau typeDec 30 2004Mar 20 2005This paper contains a preliminary study of the monodromy of certain fourth order differential equations, that were called of Calabi-Yau type in math.NT/0402386. Some of these equations can be interpreted as the Picard-Fuchs equations of a Calabi-Yau manifold ... More
A Massive Galaxy in its Core Formation Phase Three Billion Years After the Big BangJun 12 2014Most massive galaxies are thought to have formed their dense stellar cores at early cosmic epochs. However, cores in their formation phase have not yet been observed. Previous studies have found galaxies with high gas velocity dispersions or small apparent ... More
Exploring the chemical link between local ellipticals and their high-redshift progenitorsOct 25 2013We present Keck/MOSFIRE K-band spectroscopy of the first mass-selected sample of galaxies at $z\sim2.3$. Targets are selected from the 3D-HST Treasury survey. The six detected galaxies have a mean [NII]$\lambda$6584/H$\alpha$ ratio of $0.27\pm0.01$, with ... More
Towards an automated query modification assistantApr 01 2011Users who need several queries before finding what they need can benefit from an automatic search assistant that provides feedback on their query modification strategies. We present a method to learn from a search log which types of query modifications ... More
Spontaneous Symmetry Breaking and Decoherence in SuperconductorsJun 13 2007Jun 15 2007We show that superconductors have a thin spectrum associated with spontaneous symmetry breaking similar to that of antiferromagnets, while still being in full agreement with Elitzur's theorem, which forbids the spontaneous breaking of local (gauge) symmetries. ... More
Full adaptation to smoothness using randomly truncated series priors with Gaussian coefficients and inverse gamma scalingSep 06 2016We study random series priors for estimating a functional parameter (f\in L^2[0,1]). We show that with a series prior with random truncation, Gaussian coefficients, and inverse gamma multiplicative scaling, it is possible to achieve posterior contraction ... More
Testing the relativistic precession model using low frequency and kHz quasi-periodic oscillations in neutron star low mass X-ray binaries with known spinNov 17 2016We analyze all available RXTE data on a sample of 13 low mass X-ray binaries with known neutron star spin that are not persistent pulsars. We carefully measure the correlations between the centroid frequencies of the quasi-periodic oscillations (QPOs). ... More
Predicting Quiescence: The Dependence of Specific Star Formation Rate on Galaxy Size and Central Density at 0.5<z<2.5Jul 11 2016Oct 05 2016In this paper, we investigate the relationship between star formation and structure, using a mass-complete sample of 27,893 galaxies at $0.5<z<2.5$ selected from 3D-HST. We confirm that star-forming galaxies are larger than quiescent galaxies at fixed ... More
Shock Waves in Weakly Compressed Granular MediaApr 23 2013We experimentally probe nonlinear wave propagation in weakly compressed granular media, and observe a crossover from quasi-linear sound waves at low impact, to shock waves at high impact. We show that this crossover grows with the confining pressure $P_0$, ... More
Donsker theorems for diffusions: Necessary and sufficient conditionsJul 21 2005We consider the empirical process G_t of a one-dimensional diffusion with finite speed measure, indexed by a collection of functions F. By the central limit theorem for diffusions, the finite-dimensional distributions of G_t converge weakly to those of ... More
Zooming-in on the SU(2) fundamental domainOct 05 1993Oct 08 1993For SU(2) gauge theories on the three-sphere we analyse the Gribov horizon and the boundary of the fundamental domain in the 18 dimensional subspace that contains the tunnelling path and the sphaleron and on which the energy functional is degenerate to ... More
Bayesian inference with rescaled Gaussian process priorsOct 19 2007We use rescaled Gaussian processes as prior models for functional parameters in nonparametric statistical models. We show how the rate of contraction of the posterior distributions depends on the scaling factor. In particular, we exhibit rescaled Gaussian ... More
Gaussian process methods for one-dimensional diffusions: optimal rates and adaptationJun 01 2015Feb 08 2016We study the performance of nonparametric Bayes procedures for one-dimensional diffusions with periodic drift. We improve existing convergence rate results for Gaussian process (GP) priors with fixed hyper parameters. Moreover, we exhibit several possibilities ... More