A5043991132- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Time Series Analysis and Forecasting
- Spectroscopy and Chemometric Analyses
- Solar and Space Plasma Dynamics
- Machine Learning and Algorithms
- Inorganic Fluorides and Related Compounds
- Analytical Chemistry and Chromatography
- Solid-state spectroscopy and crystallography
- Chemical Synthesis and Characterization
- Pulsars and Gravitational Waves Research
- Neutrino Physics Research
- Algorithms and Data Compression
- History and Developments in Astronomy
- Service-Oriented Architecture and Web Services
- Computational Physics and Python Applications
- Neural dynamics and brain function
- Web Applications and Data Management
- Remote-Sensing Image Classification
Johns Hopkins University
2020-2024
Anhui University
2024
Rutgers, The State University of New Jersey
1998-2023
University of Oklahoma
2013-2016
Hunan Institute of Engineering
2010
We present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift $z=0.001$ to 2.26. This work features an increased sample size, span, and improved treatment systematic uncertainties comparison original Pantheon results a factor two improvement constraining power. For Flat$\Lambda$CDM model, we find $\Omega_M=0.334\pm0.018$ SNe alone. Flat$w_0$CDM measure $w_0=-0.90\pm0.14$ alone, H$_0=73.5\pm1.1$...
Abstract We present a recalibration of the photometric systems in Pantheon+ sample Type Ia supernovae (SNe Ia) including those SH0ES distance-ladder measurement H 0 . utilize large and uniform sky coverage public Pan-STARRS stellar photometry catalog to cross calibrate against tertiary standards released by individual SN surveys. The most significant updates over “SuperCal” calibration used for previous Pantheon analyses are: (1) expansion number (now 25) filters 105), (2) solving all filter...
A spectral-energy distribution (SED) model for Type Ia supernovae (SNe Ia) is a critical tool measuring precise and accurate distances across large redshift range constraining cosmological parameters. We present an improved framework, SALT3, which has several advantages over current models including the leading SALT2 (SALT2.4). While SALT3 similar philosophy, it differs from by having estimation of uncertainties, better separation color light-curve stretch, publicly available training code....
Abstract Next-generation surveys like the Legacy Survey of Space and Time (LSST) on Vera C. Rubin Observatory (Rubin) will generate orders magnitude more discoveries transients variable stars than previous surveys. To prepare for this data deluge, we developed Photometric LSST Astronomical Time-series Classification Challenge (PLAsTiCC), a competition that aimed to catalyze development robust classifiers under LSST-like conditions nonrepresentative training set large photometric test...
ABSTRACT For the past decade, SALT2 has been most common model used to fit Type Ia supernova (SN Ia) light curves for dark energy analyses. Recently, SALT3 was released, which upgraded a number of features but not yet measurements energy. Here, we evaluate impact switching from SN cosmology analysis. We train and on an identical training sample 1083 well-calibrated supernovae, ensuring that any differences found come underlying framework. publicly release results this (the SALT ‘surfaces’)....
ABSTRACT A growing number of supernovae (SNe) are now known to exhibit evidence for significant interaction with a dense, pre-existing, circumstellar medium (CSM). SNe Ibn comprise one such class that can be characterized by both rapidly evolving light curves and persistent narrow He i lines. The origin dense CSM in these systems remains pressing question, specifically concerning the progenitor system mass-loss mechanism. In this paper, we present multiwavelength data Type SN 2020nxt,...
We present the distance priors that we have derived from 2015 Planck data, and use these in combination with latest observational data Type Ia Supernovae (SNe Ia) galaxy clustering, to explore systematic uncertainties dark energy constraints. Joint Lightcurve Analysis (JLA) set of 740 SNe Ia, clustering measurements H(z)s D_A(z)/s (where s is sound horizon at drag epoch) Sloan Digital Sky Survey (SDSS) z=0.35 z=0.57 (BOSS DR12). find combined constraints are insensitive assumptions made...
We describe the simulated data sample for "Photometric LSST Astronomical Time Series Classification Challenge" (PLAsTiCC), a publicly available challenge to classify transient and variable events that will be observed by Large Synoptic Survey Telescope (LSST), new facility expected start in early 2020s. The was hosted Kaggle, ran from 2018 September 28 December 17, included 1,094 teams competing prizes. Here we provide details of 18 source models, which were not revealed until after...
A large fraction of Type Ia supernova (SN Ia) observations over the next decade will be in near-infrared (NIR), at wavelengths beyond reach current standard light-curve model for SN cosmology, SALT3 ($\sim 2800$--8700$A$ central filter wavelength). To harness this new sample and reduce future standardization systematic uncertainties, we train NIR (SALT3-NIR) up to 2 $\mu$m with open-source model-training software SALTShaker, which can easily accommodate observations. Using simulated data...
This note presents an initial survey design for the Nancy Grace Roman High-latitude Time Domain Survey. is not meant to be a final or exhaustive list of all strategy choices, but instead viable path towards achieving desired precision and accuracy dark energy measurements using Type Ia supernovae (SNe Ia). We describe that use six filters (RZYJH F) prism on Wide Field Instrument. has two tiers, one "wide" which targets SNe at redshifts up 1 "deep" targeting 1.7; each, four are used (with Y J...
We present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift $z=0.001$ to 2.26. This work features an increased sample size, span, and improved treatment systematic uncertainties comparison original Pantheon results a factor two improvement constraining power. For Flat$Λ$CDM model, we find $Ω_M=0.334\pm0.018$ SNe alone. Flat$w_0$CDM measure $w_0=-0.90\pm0.14$ alone, H$_0=73.5\pm1.1$ km...
The Photometric LSST Astronomical Time Series Classification Challenge (PLAsTiCC) is an open data challenge to classify simulated astronomical time-series in preparation for observations from the Large Synoptic Survey Telescope (LSST), which will achieve first light 2019 and commence its 10-year main survey 2022. revolutionize our understanding of changing sky, discovering measuring millions time-varying objects. In this challenge, we pose question: how well can objects sky that vary...
We present space-based ultraviolet/optical photometry and spectroscopy with the Swift Ultra-Violet/Optical Telescope Hubble Space Telescope, respectively, along ground-based optical near-infrared of supernova SN2017erp. The light curves spectra are consistent a normal Type Ia (SN Ia). Compared to previous photometric samples in near-ultraviolet (NUV), SN2017erp has colors similar NUV-red category after correcting for Milky Way host dust reddening. find difference between NUV-blue SN2011fe is...
Abstract The unknown cause of the correlation between Type Ia supernova (SN Ia) Hubble residuals and their host-galaxy masses (the “mass step”) may bias cosmological parameter measurements. To better understand mass step, we develop a SALT3 light-curve model for SN cosmology that uses 296 low-redshift SNe to derive spectral energy distribution–host-galaxy relationship. resulting has larger Ca ii H K, near-infrared triplet, Si equivalent widths in low-mass host galaxies at 2.2–2.7 σ...
Supernova (SN) classification and redshift estimation using photometric data only have become very important for the Large Synoptic Survey Telescope (LSST), given large number of SNe that LSST will observe impossibility spectroscopically following up all SNe. We investigate performance an SN classifier uses colours to classify with Random Forest algorithm. Our results in area-under-the-curve 0.98 which represents excellent classification. are able obtain a sample containing 99 per cent Ia by...
The ejecta velocities of type-Ia supernovae (SNe Ia), as measured by the Si II $\lambda 6355$ line, have been shown to correlate with other supernova properties, including color and standardized luminosity. We investigate these results using Foundation Supernova Survey, a spectroscopic data release presented here, photometry analyzed SALT2 light-curve fitter. find that do not show significant evidence for an offset in between SNe Ia high normal photospheric velocities, $\Delta c = 0.005 \pm...
Classification of transient and variable light curves is an essential step in using astronomical observations to develop understanding their underlying physical processes. However, upcoming deep photometric surveys, including the Large Synoptic Survey Telescope (LSST), will produce a deluge low signal-to-noise data for which traditional labeling procedures are inappropriate. Probabilistic classification more appropriate but incompatible with metrics used on deterministic classifications....
Abstract Few published ultraviolet (UV) spectra exist for stripped-envelope supernovae and none to date broad-lined Type Ic (SNe Ic-bl). These objects have extremely high ejecta velocities are the only supernova type directly linked gamma-ray bursts (GRBs). Here we present two epochs of HST/STIS SN Ic-bl 2014ad, first UV this class. We supplement with 26 new ground-based optical spectra, augmenting a rich spectral time series. The do not show strong features consistent broadened versions...
In order to obtain robust cosmological constraints from Type Ia supernova (SN Ia) data, we have applied Markov Chain Monte Carlo (MCMC) SN lightcurve fitting. We develop a method for sampling the resultant probability density distributions (pdf) of lightcuve parameters in MCMC likelihood analysis constrain parameters, and validate it using simulated data sets. Applying this 'joint (JLA)' set SNe Ia, find that parameter pdf's leads closer flat Universe with constant, compared usual practice...
A growing number of supernovae (SNe) are now known to exhibit evidence for significant interaction with a dense, pre-existing, circumstellar medium (CSM). SNe Ibn comprise one such class that can be characterised by both rapidly evolving light curves and persistent narrow He I lines. The origin dense CSM in these systems remains pressing question, specifically concerning the progenitor system mass-loss mechanism. In this paper, we present multi-wavelength data Type SN 2020nxt, including...
Abstract Type Iax supernovae (SNe Iax) are the largest known class of peculiar white dwarf SNe, distinct from normal Ia Ia). The unique properties SNe Iax, especially their strong photospheric lines out to extremely late times, allow us model optical spectra and derive physical parameters long-lasting photosphere. We present an extensive spectral timeseries, including 21 new spectra, SN 2014dt +11 +562 days after maximum light. able reproduce entire timeseries with a self-consistent, nearly...
We present here a re-calibration of the photometric systems used in Pantheon+ sample Type Ia supernovae (SNe Ia) including those for SH0ES distance-ladder measurement H$_0$. utilize large and uniform sky coverage public Pan-STARRS stellar photometry catalog to cross-calibrate against tertiary standards released by individual SN surveys. The most significant updates over `SuperCal' cross-calibration previous Pantheon analyses are: 1) expansion number (now 25) filters 105), 2) solving all...
The recent increase in volume and complexity of available astronomical data has led to a wide use supervised machine learning techniques. Active strategies have been proposed as an alternative optimize the distribution scarce labeling resources. However, due specific conditions which labels can be acquired, fundamental assumptions, such sample representativeness cost stability cannot fulfilled. Recommendation System for Spectroscopic followup (RESSPECT) project aims enable construction...
Context. When selecting a light curve classifier for use as part of photometric supernova Ia (SN Ia) cosmological analysis, it is common to make decisions based on metrics classification performance, such the contamination within photometrically classified SN sample, rather than measure constraining power. If former an appropriate proxy latter, this practice would eliminate computational expense full cosmology forecast in analysis pipeline design process. Aims. This study tests assumption...