A5081868610- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Geophysics and Gravity Measurements
- Advanced Statistical Methods and Models
- Remote Sensing in Agriculture
- Spectroscopy and Chemometric Analyses
- CCD and CMOS Imaging Sensors
- Advanced Statistical Process Monitoring
- Advanced Fiber Laser Technologies
- Advanced X-ray Imaging Techniques
- Methane Hydrates and Related Phenomena
- Electromagnetic Launch and Propulsion Technology
- Landslides and related hazards
- History and Developments in Astronomy
- Mechanics and Biomechanics Studies
- Cryospheric studies and observations
- Spectroscopy and Laser Applications
- Laser-Plasma Interactions and Diagnostics
- Astro and Planetary Science
University of Vienna
2020-2024
European Southern Observatory
2018-2019
University of Cambridge
2015-2018
Institute of Astronomy
2015-2016
European Space Astronomy Centre
2012-2015
We explore the connection between galaxies and dark matter halos in Milky Way (MW) quantify implications on properties of particle phenomenology low-mass galaxy formation. This is done through a probabilistic comparison luminosity function MW dwarf satellite to models based two suites zoom-in simulations. One suite dark-matter-only while other includes disk component, therefore we can effect MW's baryonic our results. apply numerous Stellar-Mass-Halo-Mass (SMHM) relations allowing for...
We establish the connection between Magellanic Clouds (MCs) and dwarf galaxy candidates discovered in Dark Energy Survey (DES) by building a dynamical model of MC satellite populations, based on an extensive suite tailor-made numerical simulations. Our takes into account response Galaxy to MCs infall, friction experienced disruption satellites their hosts. The simulation samples over uncertainties MC's proper motions, masses MW themselves, allows for flexibility intrinsic volume density...
We report the discovery of two ultra-faint satellites in vicinity Large Magellanic Cloud (LMC) data from Satellites Survey (MagLiteS). Situated 18$^{\circ}$ ($\sim 20$ kpc) LMC and separated each other by only $18^\prime$, Carina~II III form an intriguing pair. By simultaneously modeling spatial color-magnitude stellar distributions, we find that both Carina~III are likely dwarf galaxies, although this is less clear for Carina~III. There fact several obvious differences between satellites....
We announce the discovery of Aquarius~2 dwarf galaxy, a new distant satellite Milky Way, detected on fringes VST ATLAS and SDSS surveys. The object was originally identified as an overdensity Red Giant Branch stars, but chosen for subsequent follow-up based presence strong Blue Horizontal Branch, which also used to measure its distance $\sim 110$ kpc. Using deeper imaging from IMACS camera 6.5m Baade spectroscopy with DEIMOS Keck, we measured satellite's half-light radius $5.1\pm 0.8$...
We report the discovery of a nearby dwarf galaxy in constellation Hydrus, between Large and Small Magellanic Clouds. Hydrus 1 is mildy elliptical ultra-faint system with luminosity $M_V\sim$ -4.7 size $\sim$ 50 pc, located 28 kpc from Sun 24 LMC. From spectroscopy 30 member stars, we measure velocity dispersion 2.7 km/s find tentative evidence for radial gradient consistent 3 rotation. 1's indicates that dark matter dominated, but its dynamical mass-to-light ratio M/L 66 significantly...
ABSTRACT We present results from spectroscopic observations with the Michigan/ Magellan Fiber System (M2FS) of 147 stellar targets along line sight to newly discovered “ultrafaint” systems Tucana 2 (Tuc 2) and Grus 1 (Gru 1). Based on simultaneous estimates velocity stellar-atmospheric parameters, we identify 8 7 stars as probable members Tuc Gru 1, respectively. Our sample for is sufficient resolve an internal dispersion <?CDATA ${8.6}_{-2.7}^{+4.4}$?> <?MML <mml:math> <mml:msubsup>...
We present Magellan/IMACS, Anglo-Australian Telescope/AAOmega+2dF, and Very Large Telescope/GIRAFFE+FLAMES spectroscopy of the CarinaII (Car II) & Carina III III) dwarf galaxy candidates, recently discovered in Magellanic Satellites Survey (MagLiteS). identify 18 member stars Car II, including 2 binaries with variable radial velocities RR Lyrae stars. The other 14 members have a mean heliocentric velocity $v_{\rm hel} = 477.2 \pm 1.2$ km/s dispersion $\sigma_v 3.4^{+1.2}_{-0.8}$ km/s....
ABSTRACT We use a sample of powerful $z\, \approx \, 0.1$ type 2 quasars (‘obscured’; log [LAGN/erg s$^{-1}]\, \gtrsim 45$), which host kpc-scale ionized outflows and jets, to identify possible signatures AGN feedback on the total molecular gas reservoirs their galaxies. Specifically, we present Atacama Pathfinder EXperiment (APEX) observations CO(2–1) transition for nine sources CO(6–5) subset three. find that majority our reside in starburst galaxies (average specific star formation rates...
Using RR Lyrae stars in the Gaia Data Release 2 and Pan-STARRS1 we study properties of Pisces Overdensity, a diffuse sub-structure outer halo Milky Way. We show that along line sight, appears as broad long plume stretching from 40 to 110 kpc with steep distance gradient. On sky Pisces's elongated shape is aligned Magellanic Stream. follow-up VLT FORS2 spectroscopy, have measured velocity distribution candidate member shown it be Galactic but offset negative velocities. suite numerical...
X-ray reflection off the accretion disc surrounding a black hole, together with associated broad iron K$\alpha$ line, has been widely used to constrain innermost accretion-flow geometry and hole spin. Some recent measurements have revealed steep emissivity profiles in number of active galactic nuclei binaries. We explore physically motivated conditions that give rise observed disc-reflection profiles. perform set simulations based on configuration possible future high-resolution mission....
ABSTRACT We present population-orbit superposition models for external galaxies based on Schwarzschild’s orbit-superposition method, by tagging the orbits with age and metallicity. The fit density distributions, kinematic, metallicity maps from integral field unit (IFU) spectroscopy observations. validate method demonstrate its power applying it to mock data, similar those obtained Multi-Unit Spectroscopic Explorer (MUSE) IFU Very Large Telescope (VLT). These data are created Auriga galaxy...
In the past 15 years, triaxial Schwarzschild orbit-superposition code by van den Bosch et al. (2008) has been widely applied to study dynamics of galaxies. Recently, Quenneville (2022) reported a bug in orbit calculation this code, specifically mirroring procedure that is used speed up computation. We have fixed incorrect DYNAMITE, which publicly-released successor (2008). study, we provide thorough quantification how affected results dynamical analyses performed with code. compare obtained...
Context . Knowledge of the spectrograph’s instrumental profile (IP) provides important information needed for wavelength calibration and use in scientific analyses. Aims This work develops new methods IP reconstruction high-resolution spectrographs equipped with astronomical laser frequency comb (astrocomb) systems assesses impact that assumptions on shape have achieving accurate spectroscopic measurements. Methods Astrocombs produce ≈ 10 000 bright, unresolved emission lines known...
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...
Context. Pile-up in X-ray charged couple device (CCD) detectors is defined as the reconstruction of independent events same detection cell a single event during read-out cycle. can seriously compromise spectral performance, modifying both flux and shape celestial sources.
We present the discovery of a faint, resolved stellar system, BLISS J0321+0438 (BLISS 1), found in Dark Energy Camera data from first observing run Blanco Imaging Southern Sky (BLISS) Survey. 1) is located at (RA, Dec) = (177.511, -41.772) deg with heliocentric distance D 23.7$^{+1.9}_{-1.0}$ kpc. It Mv 0.0$^{+1.7}_{-0.7}$ mag, and compact, rh 4.1 +/- 1 pc, system consistent previously discovered faint halo star clusters. Using second release Gaia satellite, we measure proper motion...
Supermassive black holes (SMBHs) and nuclear star clusters (NSCs) co-exist in many galaxies. While the formation history of hole is essentially lost, NSCs preserve their evolutionary imprinted onto stellar populations kinematics. Studying SMBHs tandem might help us to ultimately reveal build-up galaxy centres. In this study, we combine large-scale VLT/MUSE high-resolution adaptive-optics-assisted VLT/SINFONI observations early-type FCC 47 with goal being assess effect a spatially...
We report the discovery of a thin stellar stream - which we name Jet crossing constellations Hydra and Pyxis. The was made in data from SLAMS survey, comprises deep $g$ $r$ imaging for $650$ square degree region above Galactic disc performed by CTIO Blanco + DECam. photometric catalogues will be publicly available. is approximately 0.18 degrees wide 10 long, though it truncated survey footprint. Its colour-magnitude diagram consistent with an old, metal-poor population at heliocentric...
Abstract We apply the barred Schwarzschild method developed by Tahmasebzadeh et al. (2022) to a S0 galaxy, NGC 4371, observed IFU instruments from TIMER and ATLAS3D projects. construct gravitational potential combining fixed black hole mass, spherical dark matter halo, stellar mass distribution deprojected 3.6 μm S4G image considering an axisymmetric disk triaxial bar. independently modelled kinematic data ATLAS3D. Both models fit remarkably well. find consistent bar pattern speed two sets...
We carried out a spectroscopic follow-up program of the four new stellar stream candidates detected by Belokurov & Koposov (2016) in outskirts Large Magellanic Cloud (LMC) using FORS2 (VLT). The medium-resolution spectra were used to measure line-of-sight velocities, estimate metallicities and classify stars into Blue Horizontal Branch (BHB) Straggler (BS) stars. Using 4-D phase-space information, we attribute approximately one half our sample Clouds, while rest is part Galactic foreground....
Dynamical models allow us to connect the motion of a set tracers underlying gravitational potential, and thus total (luminous dark) matter distribution. They are particularly useful for understanding mass spatial distribution dark (DM) in galaxy. Globular clusters (GCs) an ideal tracer population dynamical models, since they bright can be found far out into halo galaxies. We aim test how well Jeans-Anisotropic-MGE (JAM) using GCs (positions line-of-sight velocities) as constrain radial DM...
Triaxial dynamical models of massive galaxies observed in the ATLAS3D project can provide new insights into complex evolutionary processes that shape galaxies. The survey is ideal as sample comprises a good mix fast and slow rotators with vastly different mass assembly histories. We present detailed study our triaxial modelling code DYNAMITE, which superposition their stellar orbits. allow us to constrain intrinsic component, distributions visible invisible matter orbit distribution these...
In this paper, we consider the problem of reconstructing a galaxy’s stellar population-kinematic distribution function from optical integral field unit measurements. These quantities are connected via high-dimensional equation. To solve problem, propose projected Nesterov–Kaczmarz reconstruction method, which efficiently leverages structure and incorporates physical prior information such as smoothness nonnegativity constraints. test performance our approach, apply it to dataset simulated...
Context . Blob detection is a common problem in astronomy. One example stellar population modelling, where the distribution of ages and metallicities galaxy inferred from observations. In this context, blobs may correspond to stars born situ versus those accreted satellites, task blob disentangle these components. A difficulty arises when distributions come with significant uncertainties, as case for recoveries modelling spectra unresolved systems. There currently no satisfactory method...
We study the total-mass density profiles of early-type galaxies (ETGs: ellipticals and lenticulars) with globular clusters (GCs) as kinematic tracers. The goal this work is to probe total mass distribution, parameterised a double power-law profile, by constraining parameters profile flexible modelling approach. To that end, we leverage extended spatial distribution GCs from SLUGGS survey (⟨ R GC, max ⟩∼8 e ) in combination discrete dynamical modelling. use Jeans anisotropic cylindrical...