A5056437969- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Cosmology and Gravitation Theories
- Astronomical Observations and Instrumentation
- Dark Matter and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Scientific Research and Discoveries
- Data Visualization and Analytics
- Astrophysical Phenomena and Observations
- Remote Sensing in Agriculture
- Statistical and numerical algorithms
- Solar and Space Plasma Dynamics
- Spatial and Panel Data Analysis
- Space Exploration and Technology
- Machine Learning and Data Classification
- Atmospheric Ozone and Climate
- Morphological variations and asymmetry
- Geophysics and Gravity Measurements
- Astronomical and nuclear sciences
- Simulation Techniques and Applications
- Spectroscopy and Chemometric Analyses
Forschungsstätte der Evangelischen Studiengemeinschaft
2025
Heidelberg University
2017-2025
Leibniz Institute for Astrophysics Potsdam
2019-2023
Max Planck Institute for Astronomy
2015-2023
American Industrial Partners (United States)
2018
Durham University
2004
The ensemble of chemical element abundance measurements for stars, along with precision distances and orbit properties, provides high-dimensional data to study the evolution Milky Way. With this third release Galactic Archaeology HERMES (GALAH) survey, we publish 678 423 spectra 588 571 mostly nearby stars (81.2% are within <2 kpc), observed spectrograph at Anglo-Australian Telescope. This (hereafter GALAH+ DR3) includes all observations from GALAH Phase 1 (bright, main, faint 70%),...
We use the NIHAO (Numerical Investigation of Hundred Astrophysical Objects) cosmological simulations to investigate effects baryonic physics on time evolution dark matter central density profiles. The sample is made ≈70 independent high-resolution hydrodynamical galaxy formation and covers a wide mass range: 1010 ≲ Mhalo/M⊙ 1012, i.e. from dwarfs L⋆. confirm previous results dependence inner slope, α, ratio between stellar-to-halo mass, Mstar/Mhalo. show that this relation holds...
ABSTRACT The Milky Way’s (MW) stellar disc exhibits a bimodality in the [Fe/H] versus [α/Fe] plane, showing distinct high- and low-α sequences whose origin is still under debate. We examine [Fe/H]–[α/Fe] abundance plane cosmological hydrodynamical simulations of MW-like galaxies from NIHAO-UHD project show that bimodal α-sequence generic consequence gas-rich merger at some time Galaxy’s evolution. high-α sequence evolves first early galaxies, extending to high metallicities, while it formed...
We study the impact of host on dwarf galaxy properties using four new Milky Way-like, ultra high-resolution simulations, ($N_{\rm part} >10^7$) from NIHAO project. split our sample in satellite ($R<R_{200}$), nearby ($1<R/R_{200}<2.5$), and field ($R>2.5 R_{\rm 200}$) galaxies. Simulated galaxies all three groups are excellent agreement with Local Group terms of: stellar mass-velocity dispersion, mass-metallicity relation, star formation histories, mass functions. Satellites show lower...
In an effort to search for Ly$\alpha$ emission from circum- and intergalactic gas on scales of hundreds kpc around $z\sim3$ quasars, thus characterise the physical properties in emission, we have initiated extensive fast-survey with Multi Unit Spectroscopic Explorer (MUSE): Quasar Snapshot Observations MUse: Search Extended Ultraviolet eMission (QSO MUSEUM). this work, report discovery enormous nebula (ELAN) quasar SDSS~J102009.99+104002.7 at $z=3.164$, which followed-up deeper MUSE...
We use ∼100 cosmological galaxy formation 'zoom-in' simulations using the smoothed particle hydrodynamics code gasoline to study effect of baryonic processes on mass profiles cold dark matter haloes. The haloes in our range from dwarf (M200 ∼ 1010 M⊙) Milky Way 1012 masses. Our exhibit a wide halo responses, primarily varying with mass, expansion contraction, up factor ∼10 changes enclosed at 1 per cent virial radius. Confirming previous studies, response is correlated integrated efficiency...
We investigate the impact of cosmic rays (CR) and different modes CR transport on properties Milky Way-mass galaxies in cosmological magneto-hydrodynamical simulations context AURIGA project. systematically study how advection, anisotropic diffusion additional Alfvén-wave cooling affect galactic disc circum-galactic medium (CGM). Global such as stellar mass star formation rate vary little between with without various physics, whereas structural sizes, CGM densities or temperatures can be...
Simulating thin and extended galactic disks has long been a challenge in computational astrophysics. We introduce the NIHAO-UHD suite of cosmological hydrodynamical simulations Milky Way mass galaxies study stellar disk properties such as mass, size rotation velocity which agree well with observations local galaxies. In particular, reproduce age-velocity dispersion relation multi-component observed for Way. Half our show double exponential vertical profile, while others are described by...
Since the advent of $Gaia$ astrometry, it is possible to identify massive accreted systems within Galaxy through their unique dynamical signatures. One such system, $Gaia$-Sausage-Enceladus (GSE), appears be an early "building block" given its virial mass $> 10^{10}\,\mathrm{M_\odot}$ at infall ($z\sim1-3$). In order separate progenitor population from background stars, we investigate chemical properties with up 30 element abundances GALAH+ Survey Data Release 3 (DR3). To inform our choice...
Chemical abundances are an essential tool in untangling the Milky Way's enrichment history. However, evolution of interstellar medium abundance gradient with cosmic time is lost as a result radial mixing processes. For first time, we quantify many observational across Galactic disk function lookback and birth radius, $R_\text{birth}$. Using empirical approach, derive $R_\text{birth}$ estimates for 145,447 APOGEE DR17 red giant stars, based solely on their ages [Fe/H]. We explore detailed 6...
ABSTRACT We use numerical simulations to model Gaia DR3 data with the aim of constraining Milky Way (MW) bar and spiral structure parameters. show that both morphology velocity field in MW-like galactic disc models are strong functions time, changing dramatically over a few tens Myr. This suggests by finding good match observed radial field, vR(x, y), we can constrain bar-spiral orientation. Incorporating uncertainties into our is necessary data; most importantly, heliocentric distance...
ABSTRACT We study the late-time evolution of central regions two Milky Way (MW)-like simulations galaxies formed in a cosmological context, one hosting fast bar and other slow one. find that length, Rb, measurements fluctuate on dynamical time-scale by up to 100 per cent, depending spiral structure strength measurement threshold. The amplitude oscillates about 15 correlating with Rb. Tremaine–Weinberg method estimates bars’ instantaneous pattern speeds show variations around mean $\sim...
Many massive star-forming disc galaxies in the redshift range 3–0.5 are observed to have a clumpy morphology showing giant clumps of size ∼1 kpc and masses about 107–1010 M⊙. The nature fate these still under debate. In this work, we use 19 high-resolution simulations from Numerical Investigations Hundred Astrophysical Objects (NIHAO) sample study formation evolution discs high-redshift galaxies. We mock Hubble Space Telescope-CANDELS observations created with radiative transfer code...
We use cosmological hydrodynamical galaxy formation simulations from the NIHAO project to investigate impact of threshold for star on response dark matter (DM) halo baryonic processes. The fiducial threshold, $n=10\, {\rm cm}^{-3}$, results in strong expansion DM galaxies with stellar masses range $10^{7.5} < M_{star} 10^{9.5} M_{\odot}$. find that lower thresholds such as $n=0.1$ (as employed by EAGLE/APOSTLE and Illustris/AURIGA projects) do not result significant at any mass scale....
We use chemistry ([alpha/Fe] and [Fe/H]), main sequence turnoff ages, kinematics determined from H3 Survey spectroscopy Gaia astrometry to identify the birth of Galactic disk. separate in-situ accreted stars on basis angular momenta eccentricities. The high-alpha persists down at least [Fe/H]=-2.5 shows unexpected non-monotonic behavior: with increasing metallicity population first declines in [alpha/Fe], then increases over range -1.3<[Fe/H]<-0.7, again higher metallicities. number rapidly...
Recent observations of the Milky Way (MW) found an unexpected steepening star-forming gas metallicity gradient around time Gaia-Sausage-Enceladus (GSE) merger event. Here we investigate influence early ($t_{\mathrm{merger}}\lesssim5$ Gyr) massive ($M_{\mathrm{gas}}^{\mathrm{merger}}/M_{\mathrm{gas}}^{\mathrm{main}}(t_{\mathrm{merger}})\gtrsim10\%$) events such as Gaia-Sausage Enceladus in MW on evolution cold gradient. We use NIHAO-UHD suite cosmological hydrodynamical simulations MW-mass...
ABSTRACT Stars move away from their birthplaces over time via a process known as radial migration, which blurs chemo–kinematic relations used for reconstructing the Milky Way (MW) formation history. To understand true evolution of MW, one needs to take into account effects this process. We show that stellar birth radii can be derived directly data with minimum prior assumptions on Galactic enrichment This is done by first recovering metallicity gradient, $\mathrm{ d}\mathrm{[Fe/H]}(R,...
ABSTRACT It is well known that stars are subject to radial migration, i.e. over time, they move away from their birth location. This dynamical process tends mix different stellar populations and hence hinders the determination of true chemical evolution a galaxy (e.g. metallicity gradients). One way account for migration infer radii individual stars. Many attempts do so have been performed last few years, but limited Milky Way, as computing position requires precise measurements age cover...
The Milky Way underwent significant transformations in its early history, characterised by violent mergers and satellite galaxy accretion. However, recent observations reveal notable star formation events over the past 4 Gyr, likely triggered perturbations from Sagittarius dwarf galaxy. Here, we present chemical signatures of this accretion event, using [Fe/H] (metallicity) [O/Fe] (oxygen abundance) ratios thin-disc stars. In normalised age-metallicity plane, identify a discontinuous V-shape...
The satellites of the Milky Way and Andromeda represent smallest galaxies we can observe in our Universe. In this series papers, aim to shed light on their formation evolution using cosmological hydrodynamical simulations. first paper, focus galaxy properties before accretion, by simulating 27 haloes with masses between 5 × 108 1010 M⊙. Out set 19 successfully form stars, while 8 remain dark. simulated match quite well present day observed scaling relations stellar mass, size metallicity,...
The kinematics of the most metal-poor stars provide a window into early formation and accretion history Milky Way. Here, we use 5~high-resolution cosmological zoom-in simulations ($\sim~5\times10^6$ star particles) Way-like galaxies taken from NIHAO-UHD project, to investigate origin low-metallicity ([Fe/H]$\leq-2.5$). show prominent population confined disk plane, as recently discovered in ubiquity this finding suggests that Way is not unique respect. Independently history, find...
Abstract The mean Galactocentric radial velocities <?CDATA $\langle {v}_{R}\rangle (R,\varphi )$?> of luminous red giant stars within the midplane Milky Way reveal a spiral signature, which could plausibly reflect response to nonaxisymmetric perturbation gravitational potential in Galactic disk. We apply simple steady-state toy model logarithmic interpret these observations, and find good qualitative quantitative match. Presuming that amplitude is proportionate disk’s surface mass density,...
We use a sample of 83 high-resolution cosmological zoom-in simulations and semi-analytic model (SAM) to study the stochasticity galaxy formation in haloes ranging from dwarf Milky Way masses. Our simulated galaxies reproduce observed inefficiency as expressed through stellar, gas baryonic Tully-Fisher relations. For HI velocities range (70 < V 220 km/s), scatter is just 0.08 0.14 dex, consistent with intrinsic at these scales. At low (20 70 0.2-0.25 which could be tested future observations....
Recently it has been shown that a large fraction of the dwarf satellite galaxies orbiting Andromeda galaxy are surprisingly aligned in thin, extended and kinematically coherent planar structure. The presence such structure seems to challenge current Cold Dark Matter paradigm formation, which predicts more uniform distribution satellites around central objects. We show is possible obtain extended, rotating plane resembling one cosmological collisionless simulations based on model. Our new...
A large fraction of the dwarf satellites orbiting Andromeda galaxy are surprisingly aligned in a thin, extended and apparently kinematically coherent planar structure. Such structure is not easily found simulations based on Cold Dark Matter model ({\Lambda}CDM). Using 21 high resolution cosmological we analyse kinematics planes similar to one around Andromeda. We find good agreement when co-rotation characterized by line-of-sight velocity. At same time, inferred angular momenta satellites,...