Parker Fagrelius
A5036502583- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Neutrino Physics Research
- Cosmology and Gravitation Theories
- CCD and CMOS Imaging Sensors
- Scientific Research and Discoveries
- Astrophysical Phenomena and Observations
- Calibration and Measurement Techniques
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Dark Matter and Cosmic Phenomena
- Engineering Education and Pedagogy
- Infrared Target Detection Methodologies
- Solar and Space Plasma Dynamics
- Experimental Learning in Engineering
- Robotic Mechanisms and Dynamics
- Nuclear Physics and Applications
- Semiconductor Lasers and Optical Devices
- Pulsars and Gravitational Waves Research
National Solar Observatory
2024-2025
NSF’s NOIRLab
2020-2024
Community Science and Data Center
2023-2024
University of California, Berkeley
2015-2021
Lawrence Berkeley National Laboratory
2015-2021
Jet Propulsion Laboratory
2010
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 $z=1.7$....
Abstract The DESI Legacy Imaging Surveys ( http://legacysurvey.org/ ) are a combination of three public projects (the Dark Energy Camera Survey, the Beijing–Arizona Sky and Mayall z -band Survey) that will jointly image ≈14,000 deg 2 extragalactic sky visible from northern hemisphere in optical bands g , r using telescopes at Kitt Peak National Observatory Cerro Tololo Inter-American Observatory. combined survey footprint is split into two contiguous areas by Galactic plane. imaging...
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...
Previously we used the Nearby Supernova Factory sample to show that Type Ia supernovae (SNe Ia) having locally star-forming environments are dimmer than SNe passive environments. Here use Constitution together with host galaxy data from GALEX independently confirm result. The effect is seen using both SALT2 and MLCS2k2 lightcurve fitting standardization methods, brightness differences of 0.094 ± 0.037 mag for 0.155 0.041 RV = 2.5. When combined our previous measurement 0.025 SALT2. If ratio...
As part of an on-going effort to identify, understand and correct for astrophysics biases in the standardization Type Ia supernovae (SNIa) cosmology, we have statistically classified a large sample nearby SNeIa into those located predominantly younger or older environments. This classification is based on specific star formation rate measured within projected distance 1kpc from each SN location (LsSFR). important refinement compared using local directly as it provides normalization relative...
The Dark Energy Spectroscopic Instrument (DESI) was designed to conduct a survey covering 14,000 deg$^2$ over five years constrain the cosmic expansion history through precise measurements of Baryon Acoustic Oscillations (BAO). scientific program for DESI evaluated during month Survey Validation (SV) campaign before beginning full operations. This produced deep spectra tens thousands objects from each stellar (MWS), bright galaxy (BGS), luminous red (LRG), emission line (ELG), and quasar...
Abstract A system of 5020 robotic fiber positioners was installed in 2019 on the Mayall Telescope, at Kitt Peak National Observatory. The robots automatically retarget their optical fibers every 10–20 minutes, each to a precision several microns, with reconfiguration time fewer than 2 minutes. Over next 5 yr, they will enable newly constructed Dark Energy Spectroscopic Instrument (DESI) measure spectra 35 million galaxies and quasars. DESI produce largest 3D map universe date expansion...
We describe the Milky Way Survey (MWS) that will be undertaken with Dark Energy Spectroscopic Instrument (DESI) on Mayall 4m telescope at Kitt Peak National Observatory. Over next 5 yr DESI MWS observe approximately seven million stars Galactic latitudes |b|>20 degrees, an inclusive target selection scheme focused thick disk and stellar halo. also include several high-completeness samples of rare types, including white dwarfs, low-mass within 100pc Sun, horizontal branch stars. summarize...
We present the DESI 2024 galaxy and quasar baryon acoustic oscillations (BAO) measurements using over 5.7 million unique redshifts in range 0.1<z<2.1. Divided by tracer type, we utilize 300,017 galaxies from magnitude-limited Bright Galaxy Survey with 0.1<z<0.4, 2,138,600 Luminous Red Galaxies 0.4<z<1.1, 2,432,022 Emission Line 0.8<z<1.6, 856,652 quasars 0.8<z<2.1, a ~7,500 square degree footprint. The analysis was blinded at catalog-level to avoid confirmation bias. All fiducial choices of...
Abstract We present the measurement of Baryon Acoustic Oscillations (BAO) from Lyman- α (Ly ) forest high-redshift quasars with first-year dataset Dark Energy Spectroscopic Instrument (DESI). Our analysis uses over 420 000 Ly spectra and their correlation spatial distribution more than 700 quasars. An essential facet this work is development a new methodology on blinded dataset. conducted rigorous tests using synthetic data to ensure reliability our findings before unblinding. Additionally,...
The Dark Energy Spectroscopic Instrument (DESI) was designed to conduct a survey covering 14,000 deg$^2$ over five years constrain the cosmic expansion history through precise measurements of Baryon Acoustic Oscillations (BAO). scientific program for DESI evaluated during month Survey Validation (SV) campaign before beginning full operations. This produced deep spectra tens thousands objects from each stellar (MWS), bright galaxy (BGS), luminous red (LRG), emission line (ELG), and quasar...
While recent supernova cosmology research has benefited from improved measurements, current analysis approaches are not statistically optimal and will prove insufficient for future surveys. This paper discusses the limitations of cosmological analyses in treating outliers, selection effects, shape- color-standardization relations, unexplained dispersion, heterogeneous observations. We present a new Bayesian framework, called UNITY (Unified Nonlinear Inference Type-Ia cosmologY), that...
Type Ia supernova cosmology depends on the ability to fit and standardize observations of magnitudes with an empirical model. We present here a series new models Supernova spectral time that capture greater amount diversity than possible are currently customary. These entitled SuperNova Empirical MOdels (\textsc{SNEMO}\footnote{https://snfactory.lbl.gov/snemo}). The constructed using spectrophotometric from $172$ individual supernovae Nearby Factory, comprising more $2000$ spectra. Using...
We present the measurements and cosmological implications of galaxy two-point clustering using over 4.7 million unique quasar redshifts in range $0.1<z<2.1$ divided into six redshift bins a $\sim 7,500$ square degree footprint, from first year observations with Dark Energy Spectroscopic Instrument (DESI Data Release 1). By fitting full power spectrum, we extend previous DESI DR1 baryon acoustic oscillation (BAO) to include redshift-space distortions signals matter-radiation equality scale....
Abstract We present ∼115 new spectroscopically identified members of the GD-1 tidal stream observed with 5000-fiber Dark Energy Spectroscopic Instrument (DESI). confirm existence a “cocoon,” which is broad (FWHM ∼ 2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mtext>°</mml:mtext> </mml:mover> </mml:math> 932 460 pc) and kinematically hot (velocity dispersion, σ 5–8 km s −1 ) component that surrounds...
We present the Baryon Acoustic Oscillation (BAO) measurements with Lyman-alpha (LyA) forest from second data release (DR2) of Dark Energy Spectroscopic Instrument (DESI) survey. Our BAO include both auto-correlation LyA absorption observed in spectra high-redshift quasars and cross-correlation quasar positions. The total sample size is approximately a factor two larger than DR1 dataset, over 820,000 positions 1.2 million quasars. describe several significant improvements to our analysis this...
We introduce a method for identifying "twin" Type Ia supernovae, and using them to improve distance measurements. This novel approach supernova standardization is made possible by spectrophotometric time series observations from the Nearby Supernova Factory (SNfactory). begin with well-measured set of find pairs whose spectra match well across entire optical window, then test whether this leads smaller dispersion in their absolute brightnesses. analysis completed blinded fashion, ensuring...
Abstract Hot, dust-obscured galaxies, or “Hot DOGs,” are a rare, dusty, hyperluminous galaxy population discovered by the WISE mission. Predominantly at redshifts 2–3, they include most luminous known galaxies in universe. Their high luminosities likely come from accretion onto highly obscured supermassive black holes (SMBHs). We have conducted pilot survey to measure SMBH masses of five <?CDATA $z\sim 2$?> Hot DOGs via broad H α emission lines, using Keck/MOSFIRE and Gemini/FLAMINGOS-2....
We present confirmation of the cluster MOO J1142+1527, a massive galaxy discovered as part Massive and Distant Clusters WISE Survey. The is confirmed to lie at z = 1.19, using Combined Array for Research in Millimeter-wave Astronomy we robustly detect Sunyaev–Zel'dovich (SZ) decrement 13.2σ. SZ data imply mass M200m (1.1 ± 0.2) × 1015M⊙, making J1142+1527 most known > 1.15 second 1. For standard ΛCDM cosmology it further expected be one ∼5 clusters exist ≥ 1.19 over entire sky. Our ongoing...
Abstract The Dark Energy Spectroscopic Instrument (DESI) is a 5000 fiber multi-object spectrometer now being installed at the prime focus of 4 m Mayall telescope Kitt Peak. Using DESI to measure ∼35 million galaxy redshifts and using Baryon Acoustic Oscillation (BAO) technique distances, results will probe nature recently discovered mysterious component our universe called dark energy. Computer controlled robotic positioners move 120 μ diameter fibers positions galaxies whose location on sky...
Correction of Type Ia Supernova brightnesses for extinction by dust has proven to be a vexing problem. Here we study the foreground highly reddened SN 2012cu, which is projected onto lane in galaxy NGC 4772. The analysis based on multi-epoch, spectrophotometric observations spanning 3,300 - 9,200 {\AA}, obtained Nearby Factory. Phase-matched comparison spectroscopically twinned 2012cu and 2011fe across 10 epochs results best-fit color excess (E(B-V), RMS) = (1.00, 0.03) total-to-selective...
Type Ia Supernovae (SNe Ia) are widely used to measure the expansion of Universe. Improving distance measurements SNe is one technique better constrain acceleration and determine its physical nature. This document develops a new spectral energy distribution (SED) model, called SUpernova Generator And Reconstructor (SUGAR), which improves description Ia, consequently could improve measurements. model constructed from properties spectrophotometric data The Nearby Supernova Factory...