A5000887726- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Cosmology and Gravitation Theories
- Astronomical Observations and Instrumentation
- Remote Sensing in Agriculture
- Space Exploration and Technology
- Data Analysis with R
- Spacecraft and Cryogenic Technologies
- Geophysics and Sensor Technology
- Astrophysical Phenomena and Observations
- Spacecraft Design and Technology
- Solar and Space Plasma Dynamics
- Scientific Research and Discoveries
- History and Developments in Astronomy
- Advanced Image Processing Techniques
- Railway Engineering and Dynamics
- Geophysics and Gravity Measurements
IQVIA (United Kingdom)
2023
Mitchell Institute
2021-2022
Texas A&M University
2021-2022
University of Virginia
2017-2021
McCormick (United States)
2017-2021
The Ohio State University
2014-2015
According to LCDM theory, hierarchical evolution occurs on all mass scales, implying that satellites of the Milky Way should also have companions. The recent discovery ultra-faint dwarf galaxy candidates in close proximity Magellanic Clouds provides an opportunity test this theory. We present proper motion (PM) measurements for 13 32 new using Gaia data release 2. All radial velocity measurements. compare measured 3D velocities these dwarfs those expected at corresponding distance and...
We present a new measurement of the systemic proper motion Small Magellanic Cloud (SMC), based on an expanded set 30 fields containing background quasars and spanning $\sim$3 year baseline, using \textit{Hubble Space Telescope} (\textit{HST}) Wide Field Camera 3. Combining this data with our previous 5 \textit{HST} fields, additional 8 measurements from \textit{Gaia}-Tycho Astrometric Solution Catalog, brings us to total 43 SMC fields. measure $\mu_{W}$ = $-0.82$ $\pm$ 0.02 (random) 0.10...
We use properties of void populations identified in N-body simulations to forecast the ability upcoming galaxy surveys differentiate models f (R) gravity from cold dark matter cosmology. analyse multiple simulation realizations, which were designed mimic expected number densities, volumes, and redshifts Euclid satellite a lower-redshift ground-based counterpart survey, using public VIDE toolkit. examine abundances, ellipicities, radial density profiles, velocity profiles at 1.0 0.43. find...
We present the first detailed kinematic analysis of proper motions (PMs) stars in Magellanic Bridge, from both \textit{Gaia} Data Release 2 catalog and \textit{Hubble Space Telescope} Advanced Camera for Surveys data. For data, we identify select two populations Bridge region, young main sequence (MS) red giant stars. The spatial locations are compared against known H {\small I} gas structure, finding a correlation between MS gas. In fields our signal comes mainly an older turn-off...
We present analysis of the proper-motion (PM) field red clump stars in Large Magellanic Cloud (LMC) disk using Gaia Early Data Release 3 catalog. Using a kinematic model based on old with 3D velocity measurements, we construct residual PM by subtracting center-of-mass motion and internal rotation components. The reveals asymmetric patterns, including larger PMs southern disk. Comparisons between observed those five numerical simulations an LMC analog that is subject to tidal fields Milky Way...
Abstract We present the color–magnitude diagrams and star formation histories (SFHs) of seven ultra-faint dwarf galaxies: Horologium 1, Hydra 2, Phoenix Reticulum Sagittarius Triangulum Tucana derived from high-precision Hubble Space Telescope photometry. find that SFH each galaxy is consistent with them having created at least 80% stellar mass by z ∼ 6. For all galaxies, we quenching times older than 11.5 Gyr ago, compatible scenario in which reionization suppresses small dark matter halos....
ABSTRACT We combine proper motion data from Gaia EDR3 and HST with line-of-sight velocity to study the stellar kinematics of ω Cen globular cluster. Using a steady-state, axisymmetric dynamical model, we measure distribution both dark luminous mass components. Assuming Gaussian Navarro–Frenk–White profiles, depending on set, an integrated ≲106 M⊙ within half-light radius for component that is distinct component. For radial data, models non-luminous are strongly statistically preferred...
We present a new kinematic model for the Small Magellanic Cloud (SMC), using data from \gaia\ Data Release 2 catalog. identify sample of astrometrically well-behaved red giant (RG) stars belonging to SMC and cross-match with publicly available radial velocity (RV) catalogs. create 3D spatial RGs, RR Lyrae distance distributions, apply models varying rotation properties novel tidal expansion prescription generate mock proper motion (PM) When we compare this series catalogs observed RG data,...
We present deep Hubble Space Telescope (HST) photometry of the ultra-faint dwarf (UFD) galaxies Pegasus III (Peg III) and Pisces II (Psc II), two most distant satellites in halo Milky Way (MW). measure structure both galaxies, derive mass-to-light ratios with newly determined absolute magnitudes, compare our findings to expectations from UFD-mass simulations. For Peg III, we find an elliptical half-light radius $a_h{=}1.88^{+0.42}_{-0.33}$ arcminutes ($118^{+31}_{-30}$ pc)...
Abstract We present a proper motion measurement for the halo globular cluster Pyxis, using Hubble Space Telescope /ACS data as first epoch and GeMS/GSAOI Adaptive Optics second, separated by baseline of ∼5 years. This is both Pyxis calibration use Multi-Conjugate to measure an absolute faint, distant object. Consequently, we our analysis in detail. obtain <?CDATA ${\mu }_{\alpha }\,\cos (\delta )$?> = 1.09 ± 0.31 mas yr −1 μ δ 0.68 0.29 . From line-of-sight velocity, find that orbit rather...
Abstract We present the first proper motion measurement for an ultra-faint dwarf spheroidal galaxy, Segue 1, using data from Sloan Digital Sky Survey (SDSS) and Large Binocular Camera (LBC) as second epochs separated by a baseline of ∼10 years. obtain μ α cos( δ ) = −0.37 ± 0.57 mas yr −1 −3.39 0.58 . Combining this with known line-of-sight velocity, corresponds to Galactocentric V rad 84 9 <?CDATA ${V}_{\tan }={164}_{-55}^{+66}$?> km s Applying Milky Way halo masses between 0.8 1.6 × 10 12...
Abstract We use Gaia Data Release 2 proper motions of field OB stars from the Runaways and Isolated O-Type Star Spectroscopic Survey Small Magellanic Cloud (SMC) to study kinematics runaway stars. The data reveal that SMC Wing has a systemic peculiar motion relative Bar radial velocity . This unambiguously demonstrates these two regions are kinematically distinct: is moving away , towards Large with 3D consistent models for recent, direct collision between Clouds. present transverse...
We use Gaia EDR3 data to identify stars associated with six classical dwarf spheroidals (Draco, Ursa Minor, Sextans, Sculptor, Fornax, Carina) at their outermost radii, beyond nominal King stellar limiting radius. For all of the dSphs examined, we find radial velocity matches residing radius and $> 50\%$ astrometric probability (four in Draco, two eight twelve five Carina), indicating that these are respective (dSphs) high probability. compare positions our candidate "extra-tidal" orbital...
Understanding the evolutionary history of Magellanic Clouds requires an in-depth exploration and characterization stellar content in their outer regions, which ultimately are key to tracing epochs nature past interactions. We present new deep images a shell-like over-density stars outskirts Small Cloud (SMC). The shell, also detected photographic plates dating back fifties, is located at ~1.9 degr from center SMC north-east direction.The structure this feature were studied with multi-band,...
We present the first detailed chemical analysis from APOGEE-2S observations of stars in six regions recently discovered substructures outskirts Magellanic Clouds extending to 20 degrees LMC center. also present, for time, metallicity and alpha-abundance radial gradients SMC out 11 6 degrees, respectively. Our tagging includes 13 species including light, alpha, Fe-peak elements. find that abundances all these elements populating two northern periphery - along "stream"-like feature show good...
We use properties of void populations identified in N-body simulations to forecast the ability upcoming galaxy surveys differentiate models f(R) gravity from ΛCDM cosmology. analyze designed mimic densities, volumes, and clustering statistics surveys, using public VIDE toolkit. examine abundances as a basic probe at redshifts 1.0 0.4. find that stronger coupling strengths produce voids up ~20% larger radius, leading significant shift number function. As an initial estimate constraining power...
We present in this study a first analysis of the astrometric error budget absolute astrometry relative to background galaxies using adaptive optics. use for multi-conjugated optics (MCAO) images obtained with GeMS/GSAOI at Gemini South. find that it is possible obtain 0.3 mas reference precision random field 1 hour on source faint galaxies. Systematic errors are correctable below level, such overall approximately 0.4 mas. Because sources extended, we necessary correct dependency PSF centroid...
We present the method behind HubPUG, a software tool built for recovering systemic proper motions (PMs) of Hubble Space Telescope (HST) fields with two epochs observations by utilizing stars observed Gaia as foreground frame reference. HST PM experiments have typically relied on use distant background galaxies or quasi-stellar objects (QSOs) stationary sources against which to measure PMs. Without consistent profiles, are more difficult centroid, but benefit on-aggregate from their large...
We present the first detailed chemical analysis from APOGEE-2S observations of stars in six regions recently discovered substructures outskirts Magellanic Clouds extending to 20° Large Cloud (LMC) center. also present, for time, metallicity and α -abundance radial gradients LMC Small (SMC) out 11° 6°, respectively. Our tagging includes 13 species including light, -, Fe-peak elements. find that abundances all these elements populating two northern periphery, along “stream-like” feature, show...
We present VIDE, the Void IDentification and Examination toolkit, an open-source Python/C++ code for finding cosmic voids in galaxy redshift surveys N-body simulations, characterizing their properties, providing a platform more detailed analysis. At its core, VIDE uses substantially enhanced version of ZOBOV (Neyinck 2008) to calculate Voronoi tessellation estimating density field performing watershed transform construct voids. Additionally, provides significant functionality both pre-...
Abstract As new work on the proper motions (PMs) of Large Magellanic Cloud (LMC) has come out, our view history Clouds evolved. We now believe they are their first infall into Milky Way (MW), having been tidally bound at start (though not necessarily now). Combining these observations with initial PMs Small (SMC) suggests a formation mechanism Stream through stripping material from SMC. However, large uncertainties remain in exact mass LMC. present measurement systemic SMC astrometry Wide...