A5080816050- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- Astro and Planetary Science
- CCD and CMOS Imaging Sensors
- Astrophysics and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Scientific Computing and Data Management
- Advanced Fluorescence Microscopy Techniques
- Hydraulic flow and structures
- Species Distribution and Climate Change
- Cosmology and Gravitation Theories
- Solar and Space Plasma Dynamics
- Spacecraft Design and Technology
- Innovative Microfluidic and Catalytic Techniques Innovation
- Advanced Electron Microscopy Techniques and Applications
- Water Systems and Optimization
- Laser-Plasma Interactions and Diagnostics
- Geological formations and processes
- Historical Astronomy and Related Studies
- Neutrino Physics Research
New York University
2022-2024
Flatiron Health (United States)
2019-2022
Flatiron Institute
2019-2022
Simons Foundation
2019
Columbia University
2015-2018
University of Copenhagen
2013
We present results from a 220-ks observation of the galactic supernova remnant (SNR) W49B using Advanced CCD Imaging Spectrometer (ACIS) on board Chanrda X-ray Observatory. exploit these data to perform detailed spatially-resolved spectroscopic analyses across SNR with aim investigate thermodynamic properties and explosive origin W49B. find substantial variation in electron temperature absorbing column toward W49B, we show that mean metal abundances are consistent predicted yields models...
In this paper, we introduce the Local Volume TiNy Titans sample (LV-TNT), which is a part of larger body work on interacting dwarf galaxies: TNT . This LV-TNT consists 10 galaxy pairs in Universe (<30 Mpc from Milky Way), span mass ratios M*, 1/M*, 2 < 20, projected separations <100 kpc, and pair member masses log(M*/M⊙) 9.9. All have resolved synthesis maps their neutral hydrogen, are located range environments captured at various interaction stages. enables us to do comparative study...
This paper presents an example where the morphology of a single stellar stream can be used to rule out specific galactic potential form without need for velocity information. We investigate globular cluster Palomar5 (Pal 5), which is tidally disrupting into cold, thin mapped over 22 degrees on sky with typical width 0.7 degrees. generate models this by fixing Pal 5's present-day position, distance and radial via observations, while allowing its proper motion vary. In spherical dark matter...
Several long, dynamically cold stellar streams have been observed around the Milky Way Galaxy, presumably formed from tidal disruption of globular clusters. In integrable potentials---where all orbits are regular---tidal debris phase-mixes close to orbit progenitor system. However, Way's dark matter halo is expected not be fully integrable; an appreciable fraction will chaotic. This paper examines influence chaos on phase-space morphology streams. Streams even in weakly chaotic regions look...
Abstract Stars that escape globular clusters form tidal tails are predominantly shaped by the global distribution of mass in Galaxy, but also preserve a historical record small-scale perturbations. Using deep grz photometry from DECaLS, we present highly probable members associated with evaporating cluster Palomar 5. These data yield cleanest view stellar stream beyond ≈20 kpc and reveal: (1) wide, low surface-brightness extension leading tail; (2) significant density variations along...
Context. Mergers and tidal interactions between massive galaxies their dwarf satellites are a fundamental prediction of the Lambda-cold dark matter cosmology. These events thought to provide important observational diagnostics non-linear structure formation. Stellar streams in Milky Way Andromeda spectacular evidence for ongoing satellite disruption. However, constructing statistically meaningful sample beyond Local Group has proven daunting challenge, full potential deepening our...
ABSTRACT We present a novel method for constraining the length of Galactic bar using 6D phase-space information to directly integrate orbits. define pseudo-length bar, named RFreq, based on maximal extent trapped find RFreq measured from orbits is consistent with assumed potential only when and pattern speed said similar model which initial coordinates are derived. Therefore, one can measure model’s or Milky Way’s by determining leads self-consistent RFreq. When we apply this ≈210 000 stars...
Abstract Stellar streams from globular clusters (GCs) offer constraints on the nature of dark matter and have been used to explore halo structure substructure our Galaxy. Detection GC in other galaxies would broaden this endeavor a cosmological context, yet no such detected date. To enable exploration, we develop Hough Stream Spotter ( HSS ), apply it Pan-Andromeda Archaeological Survey (PAndAS) photometric data resolved stars M31's stellar halo. We first demonstrate that code can...
We quantify the frequency of companions low redshift ($0.013 < z 0.0252$), dwarf galaxies ($2 \times 10^8$ M$_\odot <$ M$_{*} 5 10^9$ M$_\odot$) that are isolated from more massive in SDSS and compare against cosmological expectations using mock observations Illustris simulation. Dwarf multiples defined as 2 or dwarfs have angular separations > 55'', projected r$_p 150$ kpc relative line-of-sight velocities $\Delta V_{\rm LOS} km/s. While catalogs predict a factor than observed SDSS, mean...
Abstract In the coming decade, thousands of stellar streams will be observed in halos external galaxies. What fundamental discoveries we make about dark matter from these streams? As a first attempt to look at questions, model Magellan/Megacam imaging Centaurus A (Cen A) disrupting dwarf companion Dwarf 3 (Dw3) and its associated stream, find out what can learned Cen halo. We develop novel galaxy stream-fitting technique generate that reproduce stream morphology visible imaging. there are...
Abstract Stellar streams form through the tidal disruption of satellite galaxies or globular clusters orbiting a host galaxy. Globular cluster are exciting since they thin (dynamically cold) and therefore sensitive to perturbations from low-mass subhalos. Since subhalo mass function differs depending on dark matter composition, these gaps can provide unique constraints models. However, current samples limited Milky Way. With its large field view, deep imaging sensitivity, high angular...
Abstract Thin stellar streams originating from globular clusters (GCs) are among the most sensitive tracers of low-mass dark matter subhalos. Joint analysis entire population will place robust constraints on subhalo mass function, and therefore nature matter. Here we use a hierarchical model GC formation to forecast total number, masses, radial distribution dissolved in Milky Way–like galaxies. Furthermore, generate mock these progenitors’ orbital histories taking into account clusters’...
We present deep optical observations of the stellar halo NGC 300, an LMC-mass galaxy, acquired with DEEP sub-component DECam Local Volume Exploration survey (DELVE) using 4 m Blanco Telescope. Our resolved star analysis reveals a large, low surface brightness stream ($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...
Discoveries of low-mass galaxy pairs and groups are increasing. Studies indicate that dwarf gas rich in the field exhibit elevated star formation rates, suggestive interactions. Lacking dynamical models observed to disentangle physical processes regulating their baryon cycles. We present new optical data first detailed theoretical model an tidal encounter between two isolated galaxies (NGC 4490 NGC 4485). This system is analogue Magellanic Clouds surrounded by a ∼50 kpc extended H i...
Thin stellar streams, formed from the tidal disruption of globular clusters, are important gravitational tools, sensitive to both global and small-scale properties dark matter. The Palomar 5 stream (Pal 5) is an exemplar within Milky Way: Its $\sim 20^\circ$ tails connect back progenitor cluster, has been used study shape, total mass, substructure fraction matter distribution Galaxy. However, most details phase-space not fully explained, dynamical models that use for other inferences...
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...
Recent observations have shown several supernova remnants (SNRs) overionized plasmas, those where ions are stripped of more electrons than they would be if in equilibrium with the electron temperature. Rapid cooling is necessary to produce this situation, yet physical origin that remains uncertain. To assess scenario responsible for overionization, paper, we identify and map plasma Galactic SNR W49B based on a 220 ks Chandra Advanced CCD Imaging Spectrometer (ACIS) observation. We performed...
Context. As the nearest accessible massive early-type galaxy, NGC 5128 presents an exceptional opportunity to measure dark matter halo parameters for a representative elliptical galaxy. Aims. Here we take advantage of rich new observational datasets large-radius tracers perform dynamical modeling Methods. We used discrete axisymmetric anisotropic Jeans approach with total tracer population nearly 1800 planetary nebulae, globular clusters, and dwarf satellite galaxies extending projected...
Flattened axisymmetric galactic potentials are known to host minor orbit families surrounding orbits with commensurable frequencies. The behavior of that belong these is fundamentally different than typical non-commensurable We investigate the evolution stellar streams on near boundaries between (separatrices) in a flattened potential. demonstrate separatrix divides into two groups stars families, and as result, diffuse more rapidly evolve elsewhere utilize Hamiltonian perturbation theory...
Abstract Low-mass galaxy pair fractions are understudied, and it is unclear whether low-mass evolve in the same way as more massive systems over cosmic time. In era of JWST, Roman, Rubin, selecting pairs a self-consistent will be critical to connect observed cosmological merger rates across all mass scales redshifts. Utilizing Illustris TNG100 simulation, we create sample physically associated (10 8 < M * 5 × 10 9 ⊙ ) high-mass (5 11 between z = 0 4.2. The fraction increases from 2.5,...
Abstract The physical mechanisms responsible for bar formation and destruction in galaxies remain a subject of debate. While we have gained valuable insight into how bars form evolve from isolated idealized simulations, the cosmological domain, galactic complex environments, with mergers gas accretion events occurring presence turbulent interstellar medium multiple star episodes, addition to coupling their host galaxies’ dark matter halos. We investigate 13 Milky Way–mass Feedback Realistic...
We present new radial velocity measurements from the Magellan and Anglo-Australian Telescopes for 174 previously known 122 newly confirmed globular clusters (GCs) around NGC 5128, nearest accessible massive early-type galaxy at D=3.8 Mpc. Remarkably, 28 of these GCs are projected radii >50' ($\gtrsim 54$ kpc), extending to $\sim 130$ kpc, in outer halo where few had been previous work. identify several subsets that spatially trace substructures visible red giant branch star maps galaxy. In...
Abstract Recent observations have revealed a trove of unexpected morphological features in many the Milky Way’s stellar streams. Explanations for such include time-dependent deformations Galactic gravitational potential, local disruptions induced by dark matter substructure, and special configurations streams’ progenitors. In this paper, we study how these morphologies can also arise certain static, nonspherical potentials that host subset resonantly trapped orbit families. The transitions,...
The physical mechanisms responsible for bar formation and destruction in galaxies remain a subject of debate. While we have gained valuable insight into how bars form evolve from isolated idealized simulations, the cosmological domain, galactic complex environments with mergers, gas accretion events, presence turbulent Inter Stellar Medium (ISM) multiple star episodes, addition to coupling their host galaxies' dark matter halos. We investigate 13 Milky Way-mass FIRE-2 (Feedback Realistic...