A5088286082- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Advanced Radiotherapy Techniques
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Radiation Therapy and Dosimetry
- Scientific Computing and Data Management
- Mechanics and Biomechanics Studies
- Space Exploration and Technology
- Meningioma and schwannoma management
- Streptococcal Infections and Treatments
- Management of metastatic bone disease
- Veterinary Equine Medical Research
- Scientific Research and Discoveries
- Effects of Radiation Exposure
- Cosmology and Gravitation Theories
- Inorganic Fluorides and Related Compounds
- Bee Products Chemical Analysis
- MRI in cancer diagnosis
- Radiation Dose and Imaging
Stockholm University
2020-2024
AlbaNova
2020-2024
Canada–France–Hawaii Telescope
2024
Liverpool John Moores University
2016-2020
Swinburne University of Technology
2012-2017
University of Victoria
2010
St Bartholomew's Hospital
2004-2008
Barnsley Hospital
1990
We introduce and provide the scientific motivation for a wide-field photometric spectroscopic chemodynamical survey of nearby early-type galaxies (ETGs) their globular cluster (GC) systems. The SAGES Legacy Unifying Globulars GalaxieS (SLUGGS) is being carried out primarily with Subaru/Suprime-Cam Keck/DEIMOS. former provides deep gri imaging over 900 arcmin2 field-of-view to characterize GC host galaxy colors spatial distributions, identify targets. NIR Ca ii triplet line-of-sight...
We present a spectro-photometric survey of 2522 extragalactic globular clusters (GCs) around twelve early-type galaxies, nine which have not been published previously. Combining space-based and multi-colour wide field ground-based imaging, with spectra from the Keck DEIMOS instrument, we obtain an average 160 GC radial velocities per galaxy, high velocity precision 15 km/s GC. After studying photometric properties systems, such as their spatial colour distributions, focus on kinematics...
Although the colour distribution of globular clusters in massive galaxies is well known to be bimodal, spectroscopic metallicity has been measured only a few galaxies. After redefining calcium triplet index–metallicity relation, we use our relation derive 903 11 early-type This largest sample cluster metallicities yet assembled. We compare these with those derived from Lick indices finding good agreement. In six eight sufficient numbers high-quality spectra find bimodality distribution. Our...
It is now well established that globular clusters (GCs) exhibit star-to-star light-element abundance variations (known as multiple stellar populations, MPs). Such chemical anomalies have been found in (nearly) all the ancient GCs (more than 10 Gyr old) of our Galaxy and its close companions, but so far no model for origin MPs able to reproduce relevant observations. To gain new insights into this phenomenon, we undertaken a photometric Hubble Space Telescope survey study with masses...
We study the total mass–density profile for a sample of 14 fast-rotator early-type galaxies (stellar masses ). combine observations from SLUGGS and ATLAS surveys to map out stellar kinematics in two dimensions, median radius four half-light radii Re (or 10 kpc) maximum 2.0–6.2 4–21 kpc). use axisymmetric dynamical models based on Jeans equations, which allow spatially varying anisotropy; employ quite general profiles dark halos; and, particular, do not place any restrictions slope. This is...
We present stellar kinematics of 22 nearby early-type galaxies (ETGs), based on two-dimensional (2D) absorption line spectroscopy out to ∼2–4 Re (effective radii), as part the ongoing SLUGGS Survey. The span a factor 20 in intrinsic luminosity, well full range environment and ETG morphology. Our data consist good velocity resolution (σinst ∼ 25 km s−1) integrated stellar-light spectra extracted from individual slitlets custom made Keck/DEIMOS slitmasks. extract measurements (V, σ, h3, h4)...
Stellar metallicity gradients in the outer regions of galaxies are a critical tool for disentangling contributions in-situ and ex-situ formed stars. In two-phase galaxy formation scenario, initial gas collapse creates steep gradients, while accretion stars satellites tends to flatten these outskirts, particularly massive galaxies. This work presents first compilation extended profiles over wide range mass. We use DEIMOS spectrograph on Keck telescope multi-slit mode obtain radial stellar 22...
We report the discovery of a remarkable ultra-compact dwarf galaxy around massive Virgo elliptical NGC 4649 (M60), which we term M60-UCD1. With dynamical mass 2.0 x 10^8 M_sun but half-light radius only ~ 24 pc, M60-UCD1 is more than any dwarfs comparable size, and arguably densest known in local universe. It has two-component structure well-fit by sum Sersic functions, with an elliptical, compact (r_h=14 pc; n 3.3) inner component round, exponential, extended (r_h=49 pc) outer component....
Recent photometric analysis of the colour-magnitude diagrams (CMDs) young massive clusters (YMCs) have found evidence for splitting in main sequence and extended turn-offs, both which been suggested to be caused by stellar rotation. Comparison observed with models has led various authors suggest a rather extreme rotation distribution, minority ($10-30$\%) stars low rotational velocities remainder ($70-90$\%) rotating near critical (i.e., break-up). We test this hypothesis searching Be within...
We present the third paper about our ongoing HST survey for search multiple stellar populations (MPs) within Magellanic Cloud clusters. report here analysis of NGC 419, a $\sim 1.5$ Gyr old, massive ($\gtrsim 2 \times 10^5 \, {\rm M_{\odot}}$) star cluster in Small (SMC). By comparing photometric data with isochrones, we set limit on [N/Fe] enhancement $\lesssim$+0.5 dex and hence find that no MPs are detected this cluster. This is surprising because, first two papers series, found evidence...
We present an analysis of the relatively low mass ($\sim2400$~M$_{\odot}$), $\sim800$~Myr, Galactic open cluster, NGC~2818, using Gaia DR2 results combined with VLT/FLAMES spectroscopy. Using proper motions and parallax measurements we are able to select a clean sample cluster members. This displays clear extended main sequence turn-off (eMSTO), phenomenon previously studied mainly in young intermediate age massive clusters Magellanic clouds. The NGC~2818 is extremely narrow, width...
We have recently shown that the $\sim2$ Gyr old Large Magellanic Cloud star cluster NGC 1978 hosts multiple populations in terms of star-to-star abundance variations [N/Fe]. These can be seen as a splitting or spread sub-giant and red giant branches (SGB RGB) when certain photometric filter combinations are used. Due to its relative youth, used place stringent limits on whether bursts star-formation taken within cluster, predicted by some models for origin populations. carry out two distinct...
We compare the results of a large grid N-body simulations with surface brightness and velocity dispersion profiles globular clusters $\omega$ Cen NGC 6624. Our models include varying stellar-mass black hole retention fractions masses central intermediate-mass (IMBH). find that an $\sim 45,000$ M$_\odot$ IMBH, whose presence has been suggested based on measured profile Cen, predicts existence about 20 fast-moving, $m>0.5$ main-sequence stars (1D) $v>60$ km/sec in arcsec Cen. However no such...
Due to longer dynamical time-scales, the outskirts of early-type galaxies retain footprint their formation and assembly. Under popular two-phase galaxy scenario, an initial in situ phase star is followed by minor merging accretion ex stars leading expectation observable transitions kinematics stellar populations on large scales. However, observing faint galactic challenging, often leaving transition unexplored. The large-scale, spatially resolved kinematic data from SAGES Legacy Unifying...
ABSTRACT We report on the detection of a black hole (NGC 1850 BH1) in ∼100-Myr-old massive cluster NGC Large Magellanic Cloud. It is binary system with main-sequence turn-off star (4.9 ± 0.4 M⊙), which starting to fill its Roche lobe and becoming distorted. Using 17 epochs Very Telescope/Multi-Unit Spectroscopic Explorer observations, we detected radial velocity variations exceeding 300 km s−1 associated target star, linked ellipsoidal measured by fourth phase Optical Gravitational Lensing...
Due to its proximity (9 Mpc) and the strongly bimodal color distribution of spectroscopically well-sampled globular cluster (GC) system, early-type galaxy NGC 3115 provides one best available tests whether bimodality widely observed in GC systems generally reflects a true metallicity bimodality. Color has alternatively been attributed nonlinear color--metallicity relation reflecting influence hot horizontal branch stars. Here we couple Subaru Suprime-Cam gi photometry with Keck/DEIMOS...
Galaxy starlight at 3.6$\mu$m is an excellent tracer of stellar mass. Here we use the latest imaging from Spitzer Space Telescope to measure total mass and effective radii in a homogeneous way for sample galaxies SLUGGS survey. These are representative nearby early-type range 10 $<$ log M$_{\ast}$/M$_{\odot}$ 11.7, our methodology can be applied other samples galaxies. We model each galaxy 2D estimate its asymptotic magnitude 1D curve-of-growth. Magnitudes converted into masses using...
In our HST photometric survey, we have been searching for multiple stellar populations (MPs) in Magellanic Clouds (MCs) massive star clusters which span a significant range of ages ($\sim 1.5-11$ Gyr). the previous papers series, shown that age cluster represents one key factors shaping origin chemical anomalies. Here present analysis four additional MCs, namely Lindsay 38, 113, NGC 2121 and 2155, recently obtained new UV observations. These are more than $\sim 10^4M_{\odot}$ between 2.5-6$...
We present adaptive optics (AO)-assisted integral-field spectroscopy of the intermediate-age star cluster NGC 419 in Small Magellanic Cloud. By investigating dynamics and rotation properties main-sequence turn-off (MSTO) stars, we demonstrate power AO-fed MUSE observations for this class objects. Based on |$1\, 049$| radial velocity measurements, determine a dynamical mass |$1.4\pm 0.2\times 10^5\, {\rm M_\odot}$| mass-to-light ratio 0.67 ± 0.08, marginally higher than simple stellar...
We use globular cluster kinematics data, primarily from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, to measure dark matter fraction (fDM) average density (〈ρDM〉) within inner 5 effective radii (Re) for 32 nearby early-type galaxies (ETGs) with stellar mass log (M*/M⊙) ranging 10.1 11.8. compare our results a simple galaxy model based on scaling relations as well cosmological hydrodynamical simulations where profile has been modified through various physical processes....
We study mass distributions within and beyond 5 effective radii (Re) in 23 early-type galaxies from the SAGES Legacy Unifying Globulars Galaxies Survey, using their globular cluster (GC) kinematic data. The data are obtained with Keck/DEep Imaging Multi-Object Spectrograph, consist of line-of-sight velocities for ∼3500 GCs, measured a high precision ∼15 km s−1 per GC extending out to ∼13 Re. obtain distribution each galaxy tracer estimator Watkins et al. account substructures, rotation...
We present a detailed study of stellar rotation in the massive 1.5 Gyr old cluster NGC 1846 Large Magellanic Cloud. Similar to other clusters at this age, shows an extended main sequence turn-off (eMSTO), and previous photometric studies have suggested it could be bimodal. In study, we use MUSE integral-field spectroscopy measure projected rotational velocities (vsini) around 1400 stars across eMSTO along upper 1846. vsini values up ~250 km/s find clear relation between star its location...
We study pre-supernova feedback in a sample of $\sim$ 4700 HII regions the nearby spiral galaxy M83, identified on their H$\alpha$ emission. pectroscopically identify Wolf-Rayet (WR) stars populating star-forming regions. For each region, we compute pressure ionised gas ($P_{\rm ion}$) and direct radiation dir}$) acting investigate how they vary with galactocentric distance, physical properties galactic environment ($P_\mathrm{DE}$). subset 500 regions, also link between terms cluster...
ABSTRACT Young star clusters enable us to study the effects of stellar rotation on an ensemble stars same age and across a wide range in mass are therefore ideal targets for understanding consequences evolution. We combine MUSE spectroscopy with HST photometry measure projected rotational velocities (Vsin i) 2184 along split main sequence turn-off (MSTO) 100 Myr-old massive ($10^5\, {\rm M_{\odot }}$) cluster NGC 1850 Large Magellanic Cloud. At fixed magnitude, we observe clear correlation...
A black hole candidate orbiting a luminous star in the Large Magellanic Cloud young cluster NGC 1850 ($\sim100$Myr) has recently been reported based on radial velocity and light curve modelling. Subsequently, an alternative explanation suggested for system: bloated post-mass transfer secondary (M$_{\rm initial} \sim 4-5M_{\odot}$, M$_{\rm current} 1-2M_{\odot}$) with more massive, yet companion (the primary). Upon reanalysis of MUSE spectra, we found that variations originally were...