A5023795173- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Adaptive optics and wavefront sensing
- Geophysics and Gravity Measurements
- History and Developments in Astronomy
- Architecture and Art History Studies
- Optical Systems and Laser Technology
- Advanced Vision and Imaging
- Spectroscopy and Laser Applications
- Molecular spectroscopy and chirality
University of Chicago
2020-2024
Yale University
2023-2024
Campbell Collaboration
2023
Netherlands Institute for Radio Astronomy
2023
Fermi National Accelerator Laboratory
2020-2021
Abstract We present the discovery of Ursa Major III/UNIONS 1, least luminous known satellite Milky Way, which is estimated to have an absolute V -band magnitude <?CDATA $+{2.2}_{-0.3}^{+0.4}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>+</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2.2</mml:mn> </mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.3</mml:mn> <mml:mn>0.4</mml:mn> </mml:msubsup> </mml:math> mag, equivalent a total stellar mass ${16}_{-5}^{+6}$?>...
Abstract We report the discovery and spectroscopic confirmation of an ultra-faint Milky Way satellite in constellation Leo. This system was discovered as a spatial overdensity resolved stars observed with Dark Energy Camera (DECam) data from early version third release DECam Local Volume Exploration (or DELVE) survey. The low luminosity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mi>V</mml:mi>...
Abstract We present the second public data release (DR2) from DECam Local Volume Exploration survey (DELVE). DELVE DR2 combines new observations with archival Dark Energy Survey, Legacy and other community programs. consists of ∼160,000 exposures that cover >21,000 deg 2 high-Galactic-latitude (∣ b ∣ > 10°) sky in four broadband optical/near-infrared filters ( g , r i z ). provides point-source automatic aperture photometry for ∼2.5 billion astronomical sources a median 5 σ depth =...
We report the discovery of six ultra-faint Milky Way satellites discovered through matched-filter searches conducted using Dark Energy Camera (DECam) data processed as part second release DECam Local Volume Exploration (DELVE) survey. Leveraging deep Gemini/GMOS-N imaging (for four candidates) well follow-up two candidates), we characterize morphologies and stellar populations these systems. find that candidates all share faint absolute magnitudes ($M_{V} \geq -3.2$ mag) old, metal-poor...
We report the discovery of Pegasus IV, an ultra-faint dwarf galaxy found in archival data from Dark Energy Camera processed by DECam Local Volume Exploration Survey. IV is a compact, stellar system ($r_{1/2} = 41^{+8}_{-6}$ pc; $M_V -4.25 \pm 0.2$ mag) located at heliocentric distance $90^{+4}_{-6}$ kpc. Based on spectra seven non-variable member stars observed with Magellan/IMACS, we confidently resolve IV's velocity dispersion, measuring $\sigma_{v} 3.3^{+1.7}_{-1.1} \text{ km s}^{-1}$...
Abstract We report results from a systematic wide-area search for faint dwarf galaxies at heliocentric distances 0.3 to 2 Mpc using the full 6 yr of data Dark Energy Survey (DES). Unlike previous searches over DES data, this specifically targeted field population located beyond Milky Way virial radius. derive our detection efficiency faint, resolved in Local Volume with set synthetic and expect be complete M V ∼ (−7, −10) mag D = (0.3, 2.0) Mpc. find no new dwarfs footprint, but we discovery...
Abstract Stars that formed with an initial mass of over 50 M ⊙ are very rare today, but they thought to be more common in the early Universe. The fates those early, metal-poor, massive stars highly uncertain. Most expected directly collapse black holes, while some may explode as a result rotationally powered engines or pair-creation instability. We present chemical abundances J0931+0038, nearby low-mass star identified follow-up SDSS-V Milky Way Mapper, which preserves signature unusual...
Abstract We present the discovery of Aquarius III, an ultra-faint Milky Way satellite galaxy identified in second data release DECam Local Volume Exploration survey. Based on deeper follow-up imaging with DECam, we find that III is a low-luminosity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mi>V</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:msubsup> <mml:mn>2.5</mml:mn>...
We present the discovery of a candidate ultra-faint Milky Way satellite, Eridanus IV (DELVE J0505$-$0931), detected in photometric data from DECam Local Volume Exploration survey (DELVE). is faint ($M_V = -4.7 \pm 0.2$), extended ($r_{1/2} 75^{+16}_{-13}$ pc), and elliptical ($\epsilon 0.54 0.1$) system at heliocentric distance $76.7^{+4.0}_{-6.1}$ kpc, with stellar population that well-described by an old, metal-poor isochrone (age $\tau \sim 13.0$ Gyr metallicity ${\rm [Fe/H] \lesssim...
The discovery of a star formed out pair-instability supernova ejecta would have massive implications for the Population III initial mass function and existence stars over 100 Msun, but none yet been found. Recently, LAMOST J1010+2358 was claimed to be that gas enriched by supernova. We present non-LTE abundance analysis new high-resolution Keck/HIRES spectrum J1010+2358. determined carbon aluminum abundances needed definitively distinguish between enrichment core-collapse Our demonstrates...
Abstract We present the discovery of DELVE 6, an ultra-faint stellar system identified in second data release DECam Local Volume Exploration (DELVE) survey. Based on a maximum-likelihood fit to its structure and population, we find that 6 is old ( τ > 9.8 Gyr at 95% confidence) metal-poor ([Fe/H] < −1.17 dex with absolute magnitude <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mi>V</mml:mi>...
We perform a search for galaxy-galaxy strong lens systems using convolutional neural network (CNN) applied to imaging data from the first public release of DECam Local Volume Exploration Survey (DELVE), which contains $\sim 520$ million astronomical sources covering 4,000$ $\mathrm{deg}^2$ southern sky $5\sigma$ point-source depth $g=24.3$, $r=23.9$, $i=23.3$, and $z=22.8$ mag. Following methodology similar searches data, we apply color magnitude cuts select catalog 11$ extended sources....
Abstract We present a spectroscopic analysis of Eridanus IV (Eri IV) and Centaurus I (Cen I), two ultrafaint dwarf galaxies the Milky Way. Using IMACS/Magellan spectroscopy, we identify 28 member stars Eri 34 Cen I. For IV, measure systemic velocity <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>v</mml:mi> </mml:mrow> <mml:mi>sys</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:msubsup> <mml:mn>31.5</mml:mn>...
We present deep optical observations of the stellar halo NGC 300, an LMC-mass galaxy, acquired with DEEP sub-component DECam Local Volume Exploration survey (DELVE) using 4 m Blanco Telescope. Our resolved star analysis reveals a large, low surface brightness stream ($M_{V}\sim-8.5$; [Fe/H] $= -1.4\pm0.15$) extending more than 40 kpc north from galaxy's center. also find other structures, including potentially additional wrap to south, which may be associated main stream. The morphology and...
We present deep Magellan$+$Megacam imaging of Centaurus I (Cen I) and Eridanus IV (Eri IV), two recently discovered Milky Way ultra-faint satellites. Our data reach $\sim2-3$ magnitudes deeper than the discovery from DECam Local Volume Exploration (DELVE) Survey. use these to constrain their distances, structural properties (e.g., half-light radii, ellipticity, position angle), luminosities. investigate whether systems show signs tidal disturbance, identify new potential member stars using...
Abstract We present deep optical observations of the stellar halo NGC 300, an LMC-mass galaxy, acquired with DEEP subcomponent DECam Local Volume Exploration survey using 4 m Blanco Telescope. Our resolved star analysis reveals a large, low surface brightness stream ( M V ∼ −8.5; [Fe/H] = −1.4 ± 0.15) extending more than 40 kpc north from galaxy’s center. also find other structures, including potentially additional wrap to south, which may be associated main stream. The morphology and...
We report the discovery of two ultra-faint stellar systems found in early data from DECam Local Volume Exploration survey (DELVE). The first system, Centaurus I (DELVE J1238-4054), is identified as a resolved overdensity old and metal-poor stars with heliocentric distance ${\rm D}_{\odot} = 116.3_{-0.6}^{+0.6}$ kpc, half-light radius $r_h 2.3_{-0.3}^{+0.4}$ arcmin, an age $\tau > 12.85$ Gyr, metallicity $Z 0.0002_{-0.0002}^{+0.0001}$, absolute magnitude $M_V -5.55_{-0.11}^{+0.11}$ mag. This...
We perform a detailed photometric and astrometric analysis of stars in the Jet stream using data from first release DECam Local Volume Exploration Survey (DELVE) DR1 \emph{Gaia} EDR3. discover that extends over $\sim 29 ^{\circ}$ on sky (increasing known length by $18^{\circ}$), which is comparable to kinematically cold Phoenix, ATLAS, GD-1 streams. Using blue horizontal branch stars, we resolve distance gradient along 0.2 kpc/deg, with distances ranging $D_\odot \sim 27-34$ kpc. use natural...
Using high precision ground-based photometry for 46 low-reddening Galactic globular clusters, in conjunction with Gaia DR2 proper motions member star selection, we have calibrated the zero point of tip red giant branch (TRGB) method at two optical ($VI$) and three near-infrared ($JHK$) wavelengths. In doing so, utilized sharply-defined zero-age horizontal (ZAHB) these clusters to relatively calibrate our cluster sample into a composite color-magnitude diagram spanning wide range...
Abstract We determine three independent Population II distance moduli to the Fornax dwarf spheroidal (dSph) galaxy, using wide-field, ground-based VI imaging acquired with Magellan-Baade telescope at Las Campanas Observatory. After subtracting foreground stars Gaia EDR3 proper motions, we measure an I -band tip of red giant branch (TRGB) magnitude <?CDATA ${I}_{0}^{\mathrm{TRGB}}=16.753\pm {0.03}_{\mathrm{stat}}\pm {0.037}_{\mathrm{sys}}$?> <mml:math...
Abstract The DECam Local Volume Exploration survey (DELVE) is a 126-night program on the 4 m Blanco Telescope at Cerro Tololo Inter-American Observatory in Chile. DELVE seeks to understand characteristics of faint satellite galaxies and other resolved stellar substructures over range environments Volume. will combine new observations with archival data cover ∼15,000 deg 2 high Galactic latitude (∣ b ∣ > 10°) southern sky 5 σ depth g , r i z ∼ 23.5 mag. In addition, region ∼2200 around...
Abstract We report the detection of three RR Lyrae (RRL) stars (two RRc and one RRab) in ultra-faint dwarf (UFD) galaxy Centaurus I (Cen I) two Milky Way (MW) δ Scuti/SX Phoenicis based on multi-epoch giz DECam observations. The are located within times half-light radius ( r h ) Cen I, while RRab star (CenI-V3) is at ∼6 . presence distant RRL clustered this tightly space represents a 4.7 σ excess relative to smooth distribution Galactic halo. Using newly detected stars, we obtain distance...
Abstract We report the discovery of three faint and ultrafaint dwarf galaxies—Sculptor A, Sculptor B, C—in direction NGC 300 ( D = 2.0 Mpc), a Large Magellanic Cloud–mass galaxy. Deep ground-based imaging with Gemini/GMOS resolves all galaxies into stars, each displaying red giant branch indicative an old, metal-poor stellar population. No young stars or H i gas are apparent, lack GALEX UV detection suggests that systems quenched. C 2.04 <mml:math...
We report the discovery of a new ultra-faint stellar system found near Magellanic Clouds in DECam Local Volume Exploration (DELVE) Survey. This system, DELVE J0155$-$6815 (DELVE 2), is located at heliocentric distance $D_{\odot} = 71 \pm 4\text{ kpc}$, which places it 3D physical separation 12 kpc from center Small Cloud (SMC) and 28 Large (LMC). 2 identified as resolved overdensity old ($\tau > 13.3\text{ Gyr}$) metal-poor (${\rm [Fe/H]} -2.0_{-0.5}^{+0.2}$ dex) stars with projected...
Abstract We demonstrate the feasibility of determining magnitudes stars on archival photographic plates using a commercially available scanner. describe one photometric approach that could serve as useful example for other studies. In particular, we measure and calibrate stellar from 1903 plate Yerkes Observatory collection, overall precision our methods is better than 0.10 mag. Notably, these measurements are dominated by intrinsic noise, rather noise introduced through...