189 citations · 1.7k across the 32 of their papers we have counts for
32 papers
Extragalactic globular cluster near-infrared spectroscopy: II. The stellar population synthesis model zero-point problem extends to the near-infrared
E. Eftekhari, A. Vazdekis, R. Riffel +5
Many recent studies have pointed out significant discrepancies between observations and models of stellar populations in the near-infrared (NIR). With current and future observing…
Extragalactic globular cluster near-infrared spectroscopy: I. Integrated near-infrared spectra of Centaurus A/NGC 5128
L. G. Dahmer-Hahn, A. L. Chies-Santos, E. Eftekhari +6
One way to constrain the evolutionary histories of galaxies is to analyse their stellar populations. In the local Universe, our understanding of the stellar population properties o…
Initial mass function variability from the integrated light of diverse stellar systems
Chloe M. Cheng, Alexa Villaume, Michael L. Balogh +4
We present a uniform analysis of the stellar initial mass function (IMF) from integrated light spectroscopy of 15 compact stellar systems (11 globular clusters in M31 and 4 ultra c…
Low-density star cluster formation: discovery of a young faint fuzzy on the outskirts of the low-mass spiral galaxy NGC 247
Aaron J. Romanowsky, Søren S. Larsen, Alexa Villaume +21
The classical globular clusters found in all galaxy types have half-light radii of 2-4 pc, which have been tied to formation in the dense cores of giant molecular…
Still at Odds with Conventional Galaxy Evolution: The Star Formation History of Ultra-Diffuse Galaxy Dragonfly 44
Kristi A. Webb, Alexa Villaume, Seppo Laine +7
We study the star formation history (SFH) of the ultra-diffuse galaxy (UDG) Dragonfly 44 (DF44) based on the simultaneous fit to near-ultraviolet to near-infrared photometry and hi…
Spatially Resolved Stellar Spectroscopy of the Ultra-diffuse Galaxy Dragonfly 44. III. Evidence for an Unexpected Star-Formation History
Alexa Villaume, Aaron J. Romanowsky, Jean Brodie +6
We use the Keck Cosmic Web Imager integral-field unit spectrograph to: 1) measure the global stellar population parameters for the ultra-diffuse galaxy (UDG) Dragonfly 44 (DF44) to…
The Assembly History of M87 Through Radial Variations in Chemical Abundances of its Field Star And Globular Cluster Populations
Alexa Villaume, Daniel Foreman-Mackey, Aaron J. Romanowsky +2
We present an extensive study of spectroscopically-derived chemical abundances for M87 and its globular cluster (GC) system. Using observations from the Mitchell spectrograph at Mc…
New Constraints on Early-Type Galaxy Assembly from Spectroscopic Metallicities of Globular Clusters in M87
Alexa Villaume, Aaron J. Romanowsky, Jean Brodie +1
The observed characteristics of globular cluster (GC) systems, such as metallicity distributions, are commonly used to place constraints on galaxy formation models. However, obtain…
Spatially Resolved Stellar Kinematics of the Ultra-Diffuse Galaxy Dragonfly 44: II. Constraints on Fuzzy Dark Matter
Asher Wasserman, Pieter van Dokkum, Aaron J. Romanowsky +9
Given the absence of directly detected dark matter (DM) as weakly interacting massive particles, there is strong interest in the possibility that DM is an ultra-light scalar field,…
Spatially-resolved stellar kinematics of the ultra diffuse galaxy Dragonfly 44. I. Observations, kinematics, and cold dark matter halo fits
Pieter van Dokkum, Asher Wasserman, Shany Danieli +8
We present spatially-resolved stellar kinematics of the well-studied ultra diffuse galaxy (UDG) Dragonfly 44, as determined from 25.3 hrs of observations with the Keck Cosmic Web I…
Extreme chemical abundance ratio suggesting an exotic origin for an ultra-diffuse galaxy
Ignacio Martin-Navarro, Aaron J. Romanowsky, Jean P. Brodie +7
Ultra diffuse galaxies are a population of extended galaxies but with relatively low luminosities. The origin of these objects remains unclear, largely due to the observational cha…
Spectroscopic Constraints on the Build-up of the Intracluster Light in the Coma Cluster
Meng Gu, Charlie Conroy, David Law +13
The stellar content of the intracluster light (ICL) provides unique insight into the hierarchical assembly process of galaxy clusters.However, the ICL is difficult to study due to…
The WAGGS project - II. The reliability of the calcium triplet as a metallicity indicator in integrated stellar light
Christopher Usher, Thomas Beckwith, Sabine Bellstedt +12
Using data from the WiFeS Atlas of Galactic Globular cluster Spectra we study the behaviour of the calcium triplet (CaT), a popular metallicity indicator in extragalactic stellar p…
Metal-rich, Metal-poor: Updated Stellar Population Models for Old Stellar Systems
Charlie Conroy, Alexa Villaume, Pieter van Dokkum +1
We present updated stellar population models appropriate for old ages (>1 Gyr) and covering a wide range in metallicities (-1.5<[Fe/H]<0.3). These models predict the full spectral…
The SLUGGS Survey: The Inner Dark Matter Density Slope of the Massive Elliptical Galaxy NGC 1407
Asher Wasserman, Aaron J. Romanowsky, Jean Brodie +7
We investigate the dark matter density profile of the massive elliptical galaxy, NGC 1407, by constructing spherically symmetric Jeans models of its field star and globular cluster…
The Stellar Populations of Two Ultra-Diffuse Galaxies from Optical and Near-infrared Photometry
Viraj Pandya, Aaron J. Romanowsky, Seppo Laine +11
We present observational constraints on the stellar populations of two ultra-diffuse galaxies (UDGs) using optical through near-infrared (NIR) spectral energy distribution (SED) fi…
Initial Mass Function Variability (or not) Among \\ Low-Velocity Dispersion, Compact Stellar Systems
Alexa Villaume, Jean Brodie, Charlie Conroy +2
Analyses of strong gravitational lenses, galaxy-scale kinematics, and absorption line stellar population synthesis (SPS) have all concluded that the stellar initial mass function (…
Galaxy populations in massive z=0.2-0.9 clusters: I. Analysis of spectroscopy
Inger Jorgensen, Kristin Chiboucas, Emily Berkson +3
We present an analysis of stellar populations in passive galaxies in seven massive X-ray clusters at z=0.19-0.89. Based on absorption line strengths measured from our high signal-t…
The Extended IRTF Spectral Library: Expanded coverage in metallicity, temperature, and surface gravity
Alexa Villaume, Charlie Conroy, Benjamin Johnson +3
We present a spectral library of 284 stars observed with the medium-resolution infrared spectrograph, SpeX, at the 3.0 meter NASA Infrared Telescope Facility (IRTF) on…
The WAGGS project - I. The WiFeS Atlas of Galactic Globular cluster Spectra
Christopher Usher, Nicola Pastorello, Sabine Bellstedt +9
We present the WiFeS Atlas of Galactic Globular cluster Spectra, a library of integrated spectra of Milky Way and Local Group globular clusters. We used the WiFeS integral field sp…
The SLUGGS survey: Using extended stellar kinematics to disentangle the formation histories of low mass S0 galaxies
Sabine Bellstedt, Duncan A. Forbes, Caroline Foster +5
We utilise the DEIMOS instrument on the Keck telescope to measure the wide-field stellar kinematics of early-type galaxies as part of the SAGES Legacy Unifying Globulars and Galaxi…
The SLUGGS Survey: a catalog of over 4000 globular cluster radial velocities in 27 nearby early-type galaxies
Duncan A. Forbes, Adebusola Alabi, Jean P. Brodie +10
Here we present positions and radial velocities for over 4000 globular clusters (GCs) in 27 nearby early-type galaxies from the SLUGGS survey. The SLUGGS survey is designed to be r…
The Initial Mass Function in the Nearest Strong Lenses from SNELLS: Assessing the Consistency of Lensing, Dynamical, and Spectroscopic Constraints
Andrew B. Newman, Russell J. Smith, Charlie Conroy +2
We present new observations of the three nearest early-type galaxy (ETG) strong lenses discovered in the SINFONI Nearby Elliptical Lens Locator Survey (SNELLS). Based on their lens…
The Stellar Initial Mass Function in Early-Type Galaxies From Absorption Line Spectroscopy. IV. A Super-Salpeter IMF in the center of NGC 1407 from Non-Parametric Models
Charlie Conroy, Pieter van Dokkum, Alexa Villaume
It is now well-established that the stellar initial mass function (IMF) can be determined from the absorption line spectra of old stellar systems, and this has been used to measure…