Arya Farahi
A5075759539- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Dark Matter and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- Remote Sensing in Agriculture
- Housing Market and Economics
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Advanced Statistical Methods and Models
- Gaussian Processes and Bayesian Inference
- Traffic Prediction and Management Techniques
- CCD and CMOS Imaging Sensors
- Energy Load and Power Forecasting
- Tensor decomposition and applications
- Climate Change Communication and Perception
- Data Quality and Management
- Plant Water Relations and Carbon Dynamics
- Esophageal Cancer Research and Treatment
- Noise Effects and Management
The University of Texas at Austin
2020-2025
Texas Fertility Center
2025
National Observatory
2023
Valongo Observatory
2023
University of Michigan
2013-2022
Carnegie Mellon University
2018-2021
Uppsala University
2017
DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with wide-area galaxy quasar redshift survey. To trace underlying matter distribution, spectroscopic targets be selected in four classes from imaging data. We measure luminous red galaxies up to $z=1.0$. probe Universe out even higher redshift, target bright [O II] emission line $z=1.7$....
We present the first cosmology results from large-scale structure in Dark Energy Survey (DES) spanning 5000 deg$^2$. perform an analysis combining three two-point correlation functions (3$\times$2pt): (i) cosmic shear using 100 million source galaxies, (ii) galaxy clustering, and (iii) cross-correlation of with lens positions. The was designed to mitigate confirmation or observer bias; we describe specific changes made sample following unblinding results. model data within flat $\Lambda$CDM...
Abstract We describe the first public data release of Dark Energy Survey, DES DR1, consisting reduced single-epoch images, co-added source catalogs, and associated products services assembled over 3 yr science operations. DR1 is based on optical/near-infrared imaging from 345 distinct nights (2013 August to 2016 February) by Camera mounted 4 m Blanco telescope at Cerro Tololo Inter-American Observatory in Chile. wide-area survey covering ∼5000 deg 2 southern Galactic cap five broad...
We present the XXL Survey, largest XMM programme totaling some 6.9 Ms to date and involving an international consortium of roughly 100 members. The Survey covers two extragalactic areas 25 deg2 each at a point-source sensitivity ~ 5E-15 erg/sec/cm2 in [0.5-2] keV band (completeness limit). survey's main goals are provide constraints on dark energy equation state from space-time distribution clusters galaxies serve as pathfinder for future, wide-area X-ray missions. review science objectives,...
DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations and the growth of structure through redshift-space distortions with wide-area galaxy quasar redshift survey. The instrument robotically-actuated, fiber-fed spectrograph capable taking up to 5,000 simultaneous spectra over wavelength range from 360 nm 980 nm. fibers feed ten three-arm spectrographs resolution $R= λ/Δλ$ between 2000 5500, depending on...
We constrain the mass–richness scaling relation of redMaPPer galaxy clusters identified in Dark Energy Survey Year 1 data using weak gravitational lensing. split into 4 × 3 bins richness λ and redshift |$z$| for ≥ 20 0.2 ≤ 0.65 measure mean masses these their stacked lensing signal. By modelling as 〈M200m|λ, |$z$|〉 = M0(λ/40)F((1 + |$z$|)/1.35)G, we normalization at 5.0 per cent level, finding M0 [3.081 ± 0.075(stat) 0.133(sys)] · 1014 M⊙ 40 0.35. The recovered index is F 1.356 0.051 (stat)...
The authors use Dark Energy Survey data on galaxy clustering and lensing from the first three years of observations combined with five prominent external datasets. They robustly constrain six potential extensions to currently prevalent cosmological paradigm \ensuremath{\Lambda}CDM (Cold Matter a constant). All would add significant new physics, such as deviations General Relativity or non-zero spatial curvature, but no evidence for physics is found.
We describe a methodology to accurately compute halo mass functions, progenitor merger rates and trees in non-cold dark matter universes using self-consistent treatment of the generalized extended Press–Schechter formalism. Our approach permits rapid exploration subhalo population galactic haloes models with variety different particle properties or rolling, truncated more complicated power spectra. make detailed comparisons analytically derived functions histories recent warm cosmological...
ABSTRACT We implement the first blind analysis of cluster abundance data to derive cosmological constraints from and weak lensing signal redMaPPer clusters in Sloan Digital Sky Survey (SDSS). simultaneously fit for parameters richness–mass relation clusters. For a flat Λ cold dark matter model with massive neutrinos, we find $S_8 \equiv \sigma _{8}(\Omega _\mathrm{ m}/0.3)^{0.5}=0.79^{+0.05}_{-0.04}$. This value is both consistent competitive that derived catalogues selected different...
Context. Open clusters (OCs) are popular tracers of the structure and evolutionary history Galactic disc. The OC population is often considered to be complete within 1.8 kpc Sun. recent Gaia Data Release 2 (DR2) allows latter claim challenged. Aims. We perform a systematic search for new OCs in direction Perseus using precise accurate astrometry from DR2. Methods. implemented coarse-to-fine method. First, we exploited spatial proximity fast density-aware partitioning sky via k -d tree domain...
We present the first joint analysis of cluster abundances and auto or cross-correlations three cosmic tracer fields: galaxy density, weak gravitational lensing shear, density split by optical richness. From a (4×2pt+N) abundances, cross-correlations, correlations measured from year data Dark Energy Survey, we obtain Ωm=0.305+0.055−0.038 σ8=0.783+0.064−0.054. This result is consistent with constraints DES-Y1 clustering two-point correlation functions for flat νΛCDM model. Consequently,...
We perform a joint analysis of the counts and weak lensing signal redMaPPer clusters selected from Dark Energy Survey (DES) Year 1 dataset. Our uses same shear source photometric redshifts estimates as were used in DES combined probes analysis. results surprisingly low values for $S_8 =\sigma_8(\Omega_{\rm m}/0.3)^{0.5}= 0.65\pm 0.04$, driven by matter density parameter, $\Omega_{\rm m}=0.179^{+0.031}_{-0.038}$, with $\sigma_8-\Omega_{\rm m}$ posteriors $2.4\sigma$ tension Y1 3x2pt results,...
We constrain cosmological and galaxy-bias parameters using the combination of galaxy clustering galaxy-galaxy lensing measurements from Dark Energy Survey Year-3 data. describe our modeling framework, choice scales analyzed, validating their robustness to theoretical uncertainties in small-scale by analyzing simulated Using a linear bias model redMaGiC sample, we obtain constraints on matter density be $\Omega_{\rm m} = 0.325^{+0.033}_{-0.034}$. also implement non-linear probe smaller that...
Abstract We present the Baryon Pasted (BP) X-ray and thermal Sunyaev–Zel’dovich (tSZ) maps derived from half-sky Uchuu light-cone simulation. These BP-Uchuu are constructed using more than 75 million dark matter halos with masses M 500 c ≥ 10 13 ⊙ within redshift range 0 ≤ z 2. A distinctive feature of our is their capability to assess influence both extrinsic intrinsic scatter caused by triaxial gaseous internal gas characteristics, respectively, at map level. show that drives substantial...
Abstract We demonstrate the ability of convolutional neural networks (CNNs) to mitigate systematics in virial scaling relation and produce dynamical mass estimates galaxy clusters with remarkably low bias scatter. present two models, CNN 1D 2D , which leverage this deep learning tool infer cluster masses from distributions member dynamics. Our first model, infers directly distribution line-of-sight velocities. second extends input space learn on joint velocities projected radial distances....
We use simulated galaxy surveys to study: (i) how membership in redMaPPer clusters maps the underlying halo population, and (ii) accuracy of a mean dynamical cluster mass, Mσ(λ), derived from stacked pairwise spectroscopy with richness λ. Using ∼130 000 pairs patterned after Sloan Digital Sky Survey (SDSS) sample study Rozo et al., we show that velocity probability density function central–satellite mi < 19 simulation matches form seen al. Through joint matching, deconstruct main Gaussian...
The cosmological utility of galaxy cluster catalogues is primarily limited by our ability to calibrate the relation between halo mass and observable proxies such as richness, X-ray luminosity or Sunyaev-Zeldovich signal. Projection effects are a particularly pernicious systematic effect that can impact proxies; structure along line sight both bias increase scatter used in abundance studies. In this work, we develop an empirical method characterize projection on redMaPPer catalogues. We use...
The massive dark matter haloes that host groups and clusters of galaxies have observable properties appear to be lognormally distributed about power-law mean scaling relations in halo mass. Coupling this assumption with either quadratic or cubic approximations the mass function log space, we derive closed-form expressions for space density as a multiple observables well forms low-order moments observable-selected samples. Using Tinker Λ cold cosmology, show analytic model reproduces results...
The center determination of a galaxy cluster from an optical finding algorithm can be offset theoretical prescriptions or $N$-body definitions its host halo center. These offsets impact the recovered statistics, affecting both richness measurements and weak lensing shear profile around clusters. This paper models centering performance \RM~cluster using archival X-ray observations \RM-selected Assuming emission peaks as fiducial centers, through analyzing their to \RM~centers, we find that...
We present and characterize the galaxy-galaxy lensing signal measured using first three years of data from Dark Energy Survey (DES Y3) covering 4132 deg$^2$. These measurements are used in DES Y3 3$\times$2pt cosmological analysis, which combines weak galaxy clustering information. use two lens samples: a magnitude-limited sample redMaGic sample, span redshift range $\sim 0.2-1$ with 10.7 M 2.6 galaxies respectively. For source catalog, we Metacalibration shape consisting $\simeq$100...
Using tens of thousands halos realized in the BAHAMAS and MACSIS simulations produced with a consistent astrophysics treatment that includes AGN feedback, we validate multi-property statistical model for stellar hot gas mass behavior hosting groups clusters galaxies. The large sample size allows us to extract fine-scale mass--property relations (MPRs) by performing local linear regression (LLR) on individual halo (${\rm M}_{\rm star}$) gas}$) as function total halo}$). We find that: 1) both...
The largest clusters of galaxies in the Universe contain vast amounts dark matter, plus baryonic matter two principal phases, a majority hot gas component and minority cold stellar phase comprising stars, compact objects, low-temperature gas. Hydrodynamic simulations indicate that highest-mass systems retain cosmic fraction baryons, natural consequence which is anti-correlation between masses stars within halos fixed total mass. We report observational detection this based on 4 elements...
We present a simultaneous analysis of galaxy cluster scaling relations between weak-lensing mass and multiple observables, across wide range wavelengths, that probe both gas stellar content. Our new hierarchical Bayesian model simultaneously considers the selection variable alongside all other observables in order to explicitly intrinsic property covariance account for effects. apply this method sample 41 clusters at $0.15<z<0.30$, with well-defined criteria based on RASS X-ray luminosity,...