A5015618920- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Remote Sensing in Agriculture
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Calibration and Measurement Techniques
- Gaussian Processes and Bayesian Inference
- Astrophysics and Cosmic Phenomena
- Scientific Research and Discoveries
- Statistical and numerical algorithms
- Dark Matter and Cosmic Phenomena
- CCD and CMOS Imaging Sensors
- Impact of Light on Environment and Health
- Astrophysics and Star Formation Studies
- Advanced Statistical Methods and Models
- Optical Systems and Laser Technology
- Big Data Technologies and Applications
- Advanced Semiconductor Detectors and Materials
- Data-Driven Disease Surveillance
- Video Surveillance and Tracking Methods
- Superconducting and THz Device Technology
University of California, Davis
2014-2024
University of Pittsburgh
2003-2014
Princeton University
1996
Here we introduce PHAT, the PHoto-z Accuracy Testing programme, an international initiative to test and compare different methods of photo-z estimation. Two environments are set up, one (PHAT0) based on simulations basic functionality codes, another (PHAT1) data from GOODS survey. The accuracy is expressed ranked by global bias, scatter, outlier rates. Most agree well PHAT0 but produce scatters that can differ up a factor two even in this idealised case. A larger spread found for PHAT1. Few...
Calibrating the photometric redshifts of >10^9 galaxies for upcoming weak lensing cosmology experiments is a major challenge astrophysics community. The path to obtaining required spectroscopic training and calibration daunting, given anticipated depths surveys difficulty in secure some faint galaxy populations. Here we present an analysis problem based on self-organizing map, method mapping distribution data high-dimensional space projecting it onto lower-dimensional representation. We...
We present a tomographic cosmic shear study from the Deep Lens Survey (DLS), which, providing limiting magnitude r_{lim}~27 (5 sigma), is designed as pre-cursor Large Synoptic Telescope (LSST) survey with an emphasis on depth. Using five redshift bins, we their auto- and cross-correlations to constrain cosmological parameters. use luminosity-dependent nonlinear model account for astrophysical systematics originating intrinsic alignments of galaxy shapes. find that leverage DLS among highest...
The Large Synoptic Survey Telescope is designed to provide an unprecedented optical imaging dataset that will support investigations of our Solar System, Galaxy and Universe, across half the sky over ten years repeated observation. However, exactly how LSST observations be taken (the observing strategy or "cadence") not yet finalized. In this dynamically-evolving community white paper, we explore detailed performance anticipated science expected depend on small changes strategy. Using...
Abstract We describe the simulated sky survey underlying second data challenge (DC2) carried out in preparation for analysis of Vera C. Rubin Observatory Legacy Survey Space and Time (LSST) by LSST Dark Energy Science Collaboration (LSST DESC). Significant connections across multiple science domains will be a hallmark LSST; DC2 program represents unique modeling effort that stresses this interconnectivity way has not been attempted before. This encompasses full end-to-end approach: starting...
We present a cosmic shear study from the Deep Lens Survey (DLS), deep BVRz multi-band imaging survey of five 4 sq. degree fields with two National Optical Astronomy Observatory (NOAO) 4-meter telescopes at Kitt Peak and Cerro Tololo. For both telescopes, change point-spread-function (PSF) shape across focal plane is complicated, exposure-to-exposure variation this position-dependent PSF significant. overcome challenge by modeling separately for individual exposures CCDs principal component...
We present DLSCL J0916.2+2951 (z=0.53), a newly discovered major cluster merger in which the collisional gas has become dissociated from collisionless galaxies and dark matter. identified using optical weak lensing observations as part of Deep Lens Survey. Our follow-up with Keck, Subaru, Hubble Space Telescope, Chandra show that is dissociative constrain matter self-interaction cross-section {\sigma}_{DM}m_{DM}^{-1}\leq7 cm^2g^{-1}. The system observed at least 0.7\pm0.2 Gyr since first...
Determining accurate redshift distributions for very large samples of objects has become increasingly important in cosmology. We investigate the impact extending cross-correlation based distribution recovery methods to include small scale clustering information. The major concern such work is ability disentangle amplitude underlying from influence evolving galaxy bias. Using multiple simulations covering a variety bias evolution scenarios, we demonstrate reliable recoveries using linear...
In this paper we present and characterize a nearest-neighbors color-matching photometric redshift estimator that features direct relationship between the precision accuracy of input magnitudes output redshifts. This aspect makes our an ideal tool for evaluating impact changes to LSST survey parameters affect measurement errors photometry, which is main motivation work (i.e., it not intended provide "best" redshifts data). We show how will improve with time over 10-year confirm nominal...
Abstract Many scientific investigations of photometric galaxy surveys require redshift estimates, whose uncertainty properties are best encapsulated by (photo-z) posterior probability density functions (PDFs). A plethora photo-z PDF estimation methodologies abound, producing discrepant results with no consensus on a preferred approach. We present the comprehensive experiment comparing twelve algorithms applied to mock data produced forLarge Synoptic Survey Telescope The Rubin Observatory...
We investigate the potential and accuracy of clustering-based redshift estimation using method proposed by M\'enard et al. (2013). This technique enables inference distributions from measurements spatial clustering arbitrary sources, a set reference objects for which redshifts are known. apply it to sample spectroscopic galaxies Sloan Digital Sky Survey show that, after carefully controlling sampling efficiency over sky, we can estimate with high accuracy. Probing full colour space SDSS...
We present The-wiZZ, an open source and user-friendly software for estimating the redshift distributions of photometric galaxies with unknown redshifts by spatially cross-correlating them against a reference sample known redshifts. The main benefit The-wiZZ is in separating angular pair finding correlation estimation from computation output clustering allowing anyone to create their without intervention "expert". It allows end user given survey select any sub-sample redshifts, match this...
Abstract Evaluating the accuracy and calibration of redshift posteriors produced by photometric (photo- z ) estimators is vital for enabling precision cosmology extragalactic astrophysics with modern wide-field surveys. photo- on a per-galaxy basis difficult, however, as real galaxies have true but not posterior. We introduce PZFlow, Python package probabilistic forward modeling galaxy catalogs normalizing flows. For simulated there natural notion “true” that can be used validation. use...
Cross-correlating the Planck High Frequency Instrument (HFI) maps against quasars from Sloan Digital Sky Survey (SDSS) DR7, we estimate intensity distribution of Cosmic Infrared Background (CIB) over redshift range 0 < z 5.We detect redshift-dependent spatial cross-correlations between two datasets using 857, 545 and 353 GHz channels obtain upper limits at 217 consistent with expectations. At all frequencies detectable signal infer a peaking around ~ 1.2 find recovered spectrum to be...
Using about 450 000 galaxies in the Deep Lens Survey, we present a detection of gravitational magnification z > 4 Lyman-break by massive foreground with 0.4 < 1.0, grouped redshift. The signal is detected at signal-to-noise ratio greater than 20, and rigorous checks confirm that it not contaminated any galaxy sample overlap inferred mass profiles are consistent earlier lensing analyses lower We then explore tomographic lens splitting our into seven redshift bins. Combining...
We apply clustering-based redshift inference to all extended sources from the Sloan Digital Sky Survey photometric catalogue, down magnitude r = 22. map relationships between colours and redshift, without assumption of sources' spectral energy distributions (SEDs). identify locate star-forming quiescent galaxies, active galactic nuclei, as well colour changes due features, such 4000 Å break, redshifting through specific filters. Our mapping is globally in good agreement with colour–redshift...
Abstract Modern galaxy surveys produce redshift probability density functions (PDFs) in addition to traditional photometric (photo- z ) point estimates. However, the storage of photo- PDFs may present a challenge with increasingly large catalogs, as we face trade-off between accuracy subsequent science measurements and limitation finite resources. This paper presents qp , Python package for manipulating parameterizations one-dimensional PDFs, suitable PDF compression. We use investigate...
Abstract Accurate photometric redshift (photo- z ) estimates are essential to the cosmological science goals of Vera C. Rubin Observatory Legacy Survey Space and Time (LSST). In this work, we use simulated photometry for mock galaxy catalogs explore how LSST photo- can be improved by addition near-infrared (NIR) and/or ultraviolet ( UV from Euclid, Wide-Field InfrarRed Telescope (WFIRST), Cosmological Advanced Optical Research (CASTOR) space telescopes. Generally, find that deeper optical...
We examine the projected correlation of galaxies with mass from small scales (<few hundred kpc) where individual dark matter halos dominate, out to 15 Mpc correlated large-scale structure dominates. investigate these profiles as a function galaxy luminosity and redshift. Selecting 0.8 million in Deep Lens Survey, we use photometric redshifts stacked weak gravitational lensing shear tomography radial 1 degree centers foreground galaxies. detect density multiple at radii larger than virial...
The uncertainty in the redshift distributions of galaxies has a significant potential impact on cosmological parameter values inferred from multi-band imaging surveys. accuracy photometric redshifts measured these surveys depends not only quality flux data, but also number modeling assumptions that enter into both training set and spectral energy distribution (SED) fitting methods estimation. In this work we focus latter, considering two types uncertainties: uncertainties SED template...
Recent works have shown that weak lensing magnification must be included in upcoming large-scale structure analyses, such as for the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), to avoid biasing cosmological results. In this work we investigate whether including has a positive impact on precision constraints, well being necessary bias. We forecast using an LSST mock catalog halo model calculate galaxy power spectra. find little effect parameter constraints clustering...