A5014210531- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Impact of Light on Environment and Health
- Reliability and Maintenance Optimization
- History and Developments in Astronomy
- Scientific Research and Discoveries
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Software Reliability and Analysis Research
- Adaptive optics and wavefront sensing
- Advanced Fluorescence Microscopy Techniques
- Cosmology and Gravitation Theories
- VLSI and Analog Circuit Testing
- Plant Water Relations and Carbon Dynamics
- Aeolian processes and effects
- Optical Polarization and Ellipsometry
- Planetary Science and Exploration
- Crystal Structures and Properties
- Astronomical and nuclear sciences
- Optical measurement and interference techniques
- Bee Products Chemical Analysis
Swinburne University of Technology
2001-2024
Instituto de Astrofísica de Canarias
2015-2024
Universidad de La Laguna
2015-2024
Centro de Estudios de Física del Cosmos de Aragón
2021
Max Planck Institute for Astronomy
2018
Max Planck Society
2018
Consejo Superior de Investigaciones Científicas
2015
University of California, Santa Cruz
2003-2011
UNSW Sydney
2003
Durham University
2000-2002
We present synthetic spectral energy distributions (SEDs) for single-age, single-metallicity stellar populations (SSPs) covering the full optical range at moderately high resolution [full width half-maximum (FWHM) = 2.3 Å]. These SEDs constitute our base models, as they combine scaled-solar isochrones with an empirical library [Medium INT Library of Empirical Spectra (MILES)], which follows chemical evolution pattern solar neighbourhood. The models rely much possible on ingredients, not just...
We present models that predict spectra of old- and intermediate-aged stellar populations at 2.51 Å (FWHM) with varying [α/Fe] abundance. The are based on the MILES library corrections from theoretical spectra. employ recent [Mg/Fe] determinations for stars BaSTI scaled-solar α-enhanced isochrones. compute a suite initial mass function (IMF) shapes slopes, covering wide age/metallicity range. Using BaSTI, we also 'base models' matching Galactic abundance pattern. confirm show flux excess...
We present the most extensive combined photometric and spectroscopic study to date of enormous globular cluster (GC) system around M87, central giant elliptical galaxy in nearby Virgo cluster. Using observations from DEIMOS LRIS at Keck, Hectospec on MMT, we derive new, precise radial velocities for 451 GCs with projected radii ~ 5 185 kpc. combine these measurements literature data a total sample 737 objects, which use re-examination kinematics GC M87. The are analyzed context archival...
Abstract The claimed detection of a diffuse galaxy lacking dark matter represents possible challenge to our understanding the properties these galaxies and formation in general. galaxy, already identified photographic plates taken summer 1976 at UK 48-in Schmidt telescope, presents normal distance-independent (e.g. colour, velocity dispersion its globular clusters). However, distance-dependent quantities are odds with those other similar galaxies, namely luminosity function sizes clusters,...
We present an analysis of archival {\it HST/ACS} imaging in the F475W ($g_{475}$), F606W ($V_{606}$) and F814W ($I_{814}$) bands globular cluster (GC) system a large (3.4 kpc effective radius) ultra-diffuse galaxy (DF17) believed located Coma Cluster galaxies. detect 11 GCs down to 5$\sigma$ completeness limit ($I_{814}=$27 mag). Correcting for background our detection limits yields total population this $27\pm5$ $V$-band specific frequency, $S_N=28\pm5$. Based on comparisons GC systems...
ABSTRACT Ultra-diffuse galaxies (UDGs) have the sizes of giants but luminosities dwarfs. A key to understanding their origins comes from total masses, low surface brightnesses ( 25.0) generally prohibit dynamical studies. Here, we report first such measurements for a UDG (VCC 1287 in Virgo cluster), based on its globular cluster system dynamics and size. From seven GCs measure mean systemic velocity v sys = km s −1 , thereby confirming association. We dispersion within 8.1 kpc, corresponding...
We have analyzed archival Hubble Space Telescope Advanced Camera for Surveys images in g and z of the globular cluster (GC) systems 53 ellipticals Virgo Cluster, spanning massive galaxies to dwarf (dEs). Several new results emerged. (1) In giant (gEs) M87 NGC 4649, there is a correlation between luminosity color individual blue (metal-poor) GCs, such that more GCs are red (metal-rich). A plausible interpretation this result self-enrichment, speculative suggestion these once possessed dark...
A detailed imaging analysis of the globular cluster (GC) system Sombrero galaxy (NGC 4594) has been accomplished using a six-image mosaic from Hubble Space Telescope Advanced Camera for Surveys. The quality data is such that contamination by foreground stars and background galaxies negligible all but faintest 5% GC luminosity function. This enables study an effectively pure sample 659 GCs until ∼2 mag fainter than turnover magnitude, which occurs at M = -7.60 ± 0.06 assumed m - 29.77. Two...
Massive relic galaxies formed the bulk of their stellar component before z~2 and have remained unaltered since then. Therefore, they represent a unique opportunity to study in great detail frozen population properties those that populated primitive Universe. We combined optical near-infrared line-strength indices order infer, out 1.5 Reff, IMF nearby massive galaxy NGC 1277. The this is bottom-heavy at all radii, with fraction low-mass stars being least factor two larger than found Milky...
Understanding the peculiar properties of Ultra Diffuse Galaxies (UDGs) via spectroscopic analysis is a challenging task requiring very deep observations and exquisite data reduction. In this work we perform one most complete characterisations stellar component UDGs to date using optical from OSIRIS at GTC. We measure radial rotation velocities, star formation histories (SFH) mean population parameters, such as ages metallicities, for sample five UDG candidates in Coma cluster. From confirm...
J-PLUS is an ongoing 12-band photometric optical survey, observing thousands of square degrees the Northern hemisphere from dedicated JAST/T80 telescope at Observatorio Astrof\'isico de Javalambre. T80Cam a 2 sq.deg field-of-view camera mounted on this 83cm-diameter telescope, and equipped with unique system filters spanning entire range. This filter combination broad, medium narrow-band filters, optimally designed to extract rest-frame spectral features (the 3700-4000\AA\ Balmer break...
Distance determinations of extremely-low-surface-brightness galaxies are expensive in terms spectroscopic time. Because this, their distances often inferred by associating such with larger structures as groups or clusters, leading to a systematic bias selecting objects high density environments. Here we report the discovery red ultra-diffuse galaxy (S82-DG-1: $r_{\mathrm{eff}}$ = 1.6 kpc; $<\mu _{g}>$ 25.7 mag arcsec$^{-2}$; $g-i$ 0.78 mag) located nearby cosmic void. We used multi-band...
We present an analysis of Hubble Space Telescope observations globular clusters (GCs) in six ultra-diffuse galaxies (UDGs) the Coma cluster, a sample that represents UDGs with large effective radii ($R_{\rm e}$), and use results to evaluate competing formation models. eliminate two significant sources systematic uncertainty determination number GCs, $N_{\rm GC}$ by using sufficiently deep (i) reach turnover GC luminosity function (ii) provide sufficient GCs which measure radial distribution....
Many recent studies have pointed out significant discrepancies between observations and models of stellar populations in the near-infrared (NIR). With current future observing facilities being focused this wavelength range, properly assessing solving these issues is utmost importance. Here, we present first application extragalactic globular cluster (GC) spectroscopy survey, evidence that GCs reveal an age zero-point problem population synthesis (SPS) models. This has already been identified...
We present the results of a meta-analysis Keck spectra extragalactic globular clusters (GCs) in sample eight galaxies, ranging from dwarfs to massive ellipticals. infer ages for metal-poor and metal-rich GCs these galaxies through comparisons Galactic GCs. Both subpopulations appear be no younger than their counterparts, with ~> 10 Gyr. This is largest which have been constrained spectroscopically. Our support formation most at high redshift. propose scenario GC that synthesizes aspects both...
We define a method for analysis of the integrated spectra extra-galactic globular clusters that provides more reliable measures age, metallicity and alpha-element abundance ratio than have so far been achieved. The involves simultaneous fitting up to 25 Lick indices in chi-squared-fitting technique maximises use available data. Here we compare three sets single stellar population (SSP) models high signal-to-noise, 20 Galactic clusters. ages, [Fe/H] ratios derived from SSP are compared...
Hickson compact groups (HCGs) constitute an interesting extreme in the range of environments which galaxies are located, as space density these small otherwise only found centres much larger clusters. The work presented here uses Lick indices to make a comparison ages and chemical compositions HCGs with those other (clusters, loose field). metallicity relative abundance ‘α-elements’ show strong correlations galaxy age central velocity dispersion, similar trends all environments. However, we...
We have performed a spectroscopic study of globular clusters (GCs) in the nearest giant elliptical NGC 5128 using 2dF facility at Anglo-Australian Telescope. obtained integrated optical spectra for total 254 GCs, 79 which are newly confirmed on basis their radial velocities and spectra. In addition, we an spectrum galaxy starlight along southern major axis. derive empirical metallicity distribution function (MDF) 207 GCs (∼14 per cent estimated GC system) based upon Milky Way GCs. This MDF...
ABSTRACT There is a growing consensus that the vast majority of ultradiffuse galaxies (UDGs) are dwarf galaxies. However, there remain few UDGs seem to be special in terms their globular cluster (GC) systems. In particular, according some authors, certain exhibit large GC populations when compared expectations from stellar (or total) mass. Among these UDGs, DF44 Coma one better-known examples. has been claimed have relatively high number GCs, $N_{\mathrm{ GC}}=74^{+18}_{-18}$, for mass only...
We report the confirmation of an old, metal-poor globular cluster in nearby dwarf irregular galaxy Sextans A, first known this galaxy. The cluster, which we designate as A-GC1, lies some 4.4 arcminutes ($\sim1.8$ kpc) to SW centre and clearly resolves into stars sub-arcsecond seeing ground-based imaging.We measure integrated magnitude $V=18.04$, corresponding absolute magnitude, $M_{V,0} = -7.85$. This gives inferred mass $M\sim$1.6$\times10^5~M\odot$, assuming a Kroupa IMF. An spectrum...
We have employed a novel way to measure the distance NGC1052-DF2, using internal stellar velocity dispersions (σ) of its globular clusters (GCs). obtained deep (15.1h), R=18,200, calcium triplet integrated-light spectra for 10 GCs in NGC1052-DF2 FLAMES GIRAFFE on VLT. For five GCs, we measured σ values, along with precision velocities whole sample. also present new photometric analysis based 40 orbits archival Hubble Space Telescope imaging 16 spectroscopically confirmed GCs. Assuming that...
The ultra-diffuse galaxy (UDG) NGC,1052-DF2 has captured the interest of astronomers ever since low velocity dispersion measured from ten globular clusters (GCs) suggested a dark matter fraction. Also, its GC system was found to be unusually bright, with luminosity function peak at least one magnitude brighter than expected for distance 20 Mpc. In this work we present an updated view NGC,1052-DF2. We analysed archival MUSE data confirm membership four additional GCs based on their radial...
Isolated galaxies are important because they probe the lowest density regimes inhabited by galaxies. We define a sample of 36 nearby isolated early-type for further study. Our isolation criteria require them to have no comparable-mass neighbours within 2 B-band magnitudes, 0.67 Mpc in plane sky and 700 km s−1 recession velocity. New wide-field optical imaging 10 with Anglo-Australian Telescope confirms their morphology relative isolation. also present four galaxy groups as control sample....