Publications (285)
Eridanus II: A Fossil from Reionization with an Off-Center Star Cluster
Joshua D. Simon, Thomas M. Brown, Alex Drlica-Wagner +10
We present deep Hubble Space Telescope (HST) photometry of the ultra-faint dwarf galaxy Eridanus II (Eri II). Eri II, which has an absolute magnitude of M_V = -7.1, is located at a…
The Relationships Among Compact Stellar Systems: A Fresh View of Ultra Compact Dwarfs
Jean P. Brodie, Aaron J. Romanowsky, Jay Strader +1
We use a combined imaging and spectroscopic survey of the nearby central cluster galaxy, M87, to assemble a sample of 34 confirmed ultra compact dwarfs (UCDs) with half-light radii…
Wide-Field Precision Kinematics of the M87 Globular Cluster System
Jay Strader, Aaron Romanowsky, Jean Brodie +6
We present the most extensive combined photometric and spectroscopic study to date of the enormous globular cluster (GC) system around M87, the central giant elliptical galaxy in t…
A multi-wavelength view of the neutron star binary 1FGL J1417.7--4402: A progenitor to canonical millisecond pulsars
Samuel J. Swihart, Jay Strader, Laura Shishkovsky +6
The Fermi -ray source 1FGL J1417.7--4407 (J1417) is a compact X-ray binary with a neutron star primary and a red giant companion in a 5.4 day orbit. This initial conclusi…
Transients from the Cataclysmic Deaths of Cataclysmic Variables
Brian D. Metzger, Yossef Zenati, Laura Chomiuk +2
We explore the observational appearance of the merger of a low-mass star with a white dwarf (WD) binary companion. We are motivated by Schreiber et al. (2016), who found that multi…
Hyper Wide Field Imaging of the Local Group Dwarf Irregular Galaxy IC 1613: An Extended Component of Metal-poor Stars
Ragadeepika Pucha, Jeffrey L. Carlin, Beth Willman +10
Stellar halos offer fossil evidence for hierarchical structure formation. Since halo assembly is predicted to be scale-free, stellar halos around low-mass galaxies constrain proper…
The SLUGGS Survey: Calcium Triplet-based Spectroscopic Metallicities for Over 900 Globular Clusters
Christopher Usher, Duncan A. Forbes, Jean P. Brodie +6
Although the colour distribution of globular clusters in massive galaxies is well known to be bimodal, the spectroscopic metallicity distribution has been measured in only a few ga…
Filling the gap: a new class of old star cluster?
Duncan Forbes, Vincenzo Pota, Christopher Usher +5
It is not understood whether long-lived star clusters possess a continuous range of sizes and masses (and hence densities), or if rather, they should be considered as distinct type…
A Deep Search for Faint Chandra X-ray Sources, Radio Sources, and Optical Counterparts in NGC 6752
Haldan N. Cohn, Phyllis M. Lugger, Yue Zhao +6
We report the results of a deep search for faint Chandra X-ray sources, radio sources, and optical counterparts in the nearby, core-collapsed globular cluster, NGC 6752. We combine…
Evidence for the disky origin of luminous Virgo dwarf ellipticals from the kinematics of their globular cluster systems
Michael A. Beasley, A. Javier Cenarro, Jay Strader +1
We report evidence for dynamically significant rotation in the globular cluster systems of two luminous Virgo dwarf ellipticals, VCC1261 and VCC1528. Including previous results for…
Science-Driven Optimization of the LSST Observing Strategy
LSST Science Collaboration, Phil Marshall, Timo Anguita +102
The Large Synoptic Survey Telescope is designed to provide an unprecedented optical imaging dataset that will support investigations of our Solar System, Galaxy and Universe, acros…
Astro2020 Science White Paper: Populations of Black Holes in Binaries
Thomas J. Maccarone, Laura Chomiuk, James Miller-Jones +9
Black holes in binary star systems are vital for understanding the process of pr oducing gravitational wave sources, understanding how supernovae work, and for p roviding fossil ev…
The Chemical Properties of Milky Way and M31 Globular Clusters: II. Stellar Population Model Predictions
Michael A. Beasley, Jean P. Brodie, Jay Strader +4
We derive ages, metallicities and [alpha/Fe] ratios from the integrated spectra of 23 globular clusters in M31, by employing multivariate fits to two stellar population models. In…
The SLUGGS survey: Probing the supermassive black hole connection with bulges and haloes using red and blue globular cluster systems
Vincenzo Pota, Alister W. Graham, Duncan A. Forbes +3
Understanding whether the bulge or the halo provides the primary link to the growth of supermassive black holes has strong implications for galaxy evolution and supermassive black…
Constraining globular cluster formation through studies of young massive clusters - III. A lack of gas and dust in massive stellar clusters in the LMC and SMC
Nate Bastian, Jay Strader
Scenarios that invoke multiple episodes of star formation within young globular clusters (GCs) to explain the observed chemical and photometric anomalies in GCs, require that clust…
A Path to an All-Sky Survey with Roman
Jiwon Jesse Han, Anirudh Chiti, Kai-Feng Chen +93
A deep, space-based, all-sky near-infrared survey carried out with the Nancy Grace Roman Space Telescope would constitute a foundational astronomical infrastructure for decades to…
Streams, Shells, and Substructures in the Accretion-Built Stellar Halo of NGC 300
Catherine E. Fielder, David J. Sand, Michael G. Jones +27
We present deep optical observations of the stellar halo of NGC 300, an LMC-mass galaxy, acquired with the DEEP sub-component of the DECam Local Volume Exploration survey (DELVE) u…
The SAGES Legacy Unifying Globulars and GalaxieS Survey (SLUGGS): Sample definition, methods, and initial results
Jean P. Brodie, Aaron J. Romanowsky, Jay Strader +14
We introduce and provide the scientific motivation for a wide-field photometric and spectroscopic chemodynamical survey of nearby early-type galaxies (ETGs) and their globular clus…
A New Candidate Transitional Millisecond Pulsar in the Sub-luminous Disk State: 4FGL J0407.7--5702
Jessie M. Miller, Samuel J. Swihart, Jay Strader +7
We report the discovery of a variable optical and X-ray source within the error ellipse of the previously unassociated Fermi Large Area Telescope -ray source 4FGL J0407.7--5702…
An Exceptional Dimming Event for a Massive, Cool Supergiant in M51
Jacob E. Jencson, David J. Sand, Jennifer E. Andrews +6
We present the discovery of an exceptional dimming event in a cool supergiant star in the Local Volume spiral M51. The star, dubbed M51-DS1, was found as part of a Hubble Space Tel…
A SLUGGS and Gemini/GMOS combined study of the elliptical galaxy M60: wide-field photometry and kinematics of the globular cluster system
Vincenzo Pota, Jean P. Brodie, Terry Bridges +20
We present new wide-field photometry and spectroscopy of the globular clusters (GCs) around NGC 4649 (M60), the third brightest galaxy in the Virgo cluster. Imaging of NGC 4649 was…
Old Massive Globular Clusters and the Stellar Halo of the Dwarf Starburst Galaxy NGC 4449
Jay Strader, Anil C. Seth, Nelson Caldwell
We use Hubble Space Telescope imaging to show that the nearby dwarf starburst galaxy NGC 4449 has an unusual abundance of luminous red star clusters. Joint constraints from integra…
Hubble Space Telescope Observations of NGC 253 Dwarf Satellites: Discovery of Three Ultra-faint Dwarf Galaxies
Burçin Mutlu-Pakdil, David J. Sand, Denija CrnojeviÄ +8
We present deep Hubble Space Telescope imaging of five faint dwarf galaxies associated with the nearby spiral NGC 253 (D3.5 Mpc). Three of these are newly discovered ultra…
Surprisingly Strong K-band Emission Found in Low Luminosity Active Galactic Nuclei
Antoine Dumont, Anil Seth, Jay Strader +3
We examine the near-infrared (NIR) emission from low-luminosity AGNs (LLAGNs). Our galaxy sample includes 15 objects with detected 2-10 keV X-ray emission, dynamical black hole mas…
The SLUGGS Survey: stellar kinematics, kinemetry and trends at large radii in 25 early-type galaxies
Caroline Foster, Nicola Pastorello, Joel Roediger +9
Due to longer dynamical timescales, the outskirts of early-type galaxies retain the footprint of their formation and assembly. Under the popular two-phase galaxy formation scenario…
Measuring Consistent Masses for 25 Milky Way Globular Clusters
Brian Kimmig, Anil Seth, Inese I. Ivans +4
We present central velocity dispersions, masses, mass to light ratios (s), and rotation strengths for 25 Galactic globular clusters. We derive radial velocities of 1951 stars…
A New Likely Redback Millisecond Pulsar Binary with a Massive Neutron Star: 4FGL J2333.1--5527
Samuel J. Swihart, Jay Strader, Ryan Urquhart +7
We present the discovery of a likely new redback millisecond pulsar binary associated with the \emph{Fermi} -ray source 4FGL J2333.1--5527. Using optical photometric and spectr…
Detection of Supermassive Black Holes in Two Virgo Ultracompact Dwarf Galaxies
Christopher P. Ahn, Anil C. Seth, Mark den Brok +13
We present the detection of supermassive black holes (BHs) in two Virgo ultracompact dwarf galaxies (UCDs), VUCD3 and M59cO. We use adaptive optics assisted data from the Gemini/NI…
Old Globular Clusters Masquerading as Young in NGC 4365?
Jean P. Brodie, Jay Strader, Glenda Denicolo +5
High signal-to-noise, low-resolution spectra have been obtained for 22 globular clusters (GCs) in NGC 4365. Some of these were selected as probable representatives of an intermedia…
A Complete Census of Luminous Stellar Variability on Day to Decade Timescales
Charlie Conroy, Jay Strader, Pieter van Dokkum +6
Stellar photometric variability offers a novel probe of the interior structure and evolutionary state of stars. Here we present a census of stellar variability on day to decade tim…
The fastest stars in the Galaxy
Kareem El-Badry, Ken J. Shen, Vedant Chandra +18
We report a spectroscopic search for hypervelocity white dwarfs (WDs) that are runaways from Type Ia supernovae (SNe Ia) and related thermonuclear explosions. Candidates are select…
4FGL J1120.0-2204: A Unique Gamma-ray Bright Neutron Star Binary with an Extremely Low Mass Proto-White Dwarf
Samuel J. Swihart, Jay Strader, Elias Aydi +5
We have discovered a new X-ray emitting compact binary that is the likely counterpart to the unassociated Fermi-LAT GeV -ray source 4FGL J1120.0-2204, the second brightest Ferm…
Direct Evidence for an Enhancement of Helium in Giant Stars in Omega Centauri
A. K. Dupree, Jay Strader, Graeme H. Smith
The double main sequence identified in the globular cluster Omega Centauri has been interpreted using isochrones to indicate a large variation in the abundance of helium. If true,…
Variable stars in the core of the globular cluster M3
Jay Strader, Henry O. Everitt, Stephen Danford
We present the results of a survey for variable stars in the core of the globular cluster M3. Our findings include the discovery of eleven new or suspected variables, including a p…
X-Ray Spectroscopy of Newly Identified ULXs Associated With M87's Globular Cluster Population
Kristen C. Dage, Stephen E. Zepf, Erica Thygesen +5
We have identified seven ultraluminous X-ray sources (ULXs) which are coincident with globular cluster candidates (GCs) associated with M87. ULXs in the old GC environment represen…
On the black hole content and initial mass function of 47 Tuc
Vincent Hénault-Brunet, Mark Gieles, Jay Strader +3
The globular cluster (GC) 47 Tuc has recently been proposed to host an intermediate-mass black hole (IMBH) or a population of stellar-mass black holes (BHs). To shed light on its d…
Optical spectroscopy of the high-mass gamma-ray binary 1FGL J1018.6-5856: A probable neutron star primary
Jay Strader, Laura Chomiuk, C. C. Cheung +2
We present medium-resolution optical spectroscopy with the SOAR telescope of the O star secondary of the high-mass gamma-ray binary 1FGL J1018.6-5856 to help determine whether the…
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…
Stellar populations of Globular Clusters in the Elliptical galaxy NGC1407
A. Javier Cenarro, Michael A. Beasley, Jay Strader +2
We present high-quality, Keck spectroscopic data for a sample of 20 globular clusters (GCs) in the massive E0 galaxy NGC1407. A subset of twenty line-strength indices of the Lick/I…
Radially Extended Kinematics in the S0 Galaxy NGC 2768 from Planetary Nebulae, Globular Clusters and Starlight
Duncan A. Forbes, Arianna Cortesi, Vincenzo Pota +7
There are only a few tracers available to probe the kinematics of individual early-type galaxies beyond one effective radius. Here we directly compare a sample of planetary nebulae…
Multi-wavelength observations of a new redback millisecond pulsar candidate: 3FGL J0954.8-3948
Kwan-Lok Li, Xian Hou, Jay Strader +6
We present a multi-wavelength study of the unassociated Fermi-LAT source, 3FGL J0954.8-3948, which is likely the gamma-ray counterpart of a 9.3-hour binary in the field. With more…
Multiwavelength Follow-up Observations of the Tidal Disruption Event Candidate 2XMMi J184725.1-631724
Dacheng Lin, Jay Strader, Eleazar R. Carrasco +5
The ultrasoft X-ray flare 2XMMi J184725.1-631724 was serendipitously detected in two XMM-Newton observations in 2006 and 2007, with a peak luminosity of 6X10^43 erg/s. It was sugge…
Supersoft X-ray emission from a white dwarf binary not powered by nuclear fusion
Thomas J. Maccarone, Thomas J. Nelson, Peter J. Brown +17
Supersoft X-ray sources are stellar objects which emit X-rays with temperatures of about 1 million Kelvin and luminosities well in excess of what can be produced by stellar coronae…
The SLUGGS Survey: HST/ACS Mosaic Imaging of the NGC 3115 Globular Cluster System
Zachary G. Jennings, Jay Strader, Aaron J. Romanowsky +6
We present HST/ACS and photometry and half-light radii measurements of 360 globular cluster (GC) candidates around the nearby S0 galaxy NGC 3115. We also includ…
Spectral Insights and Evolutionary Pathways of Globular Cluster ULX in NGC 1399: A Two-Decade X-ray and Optical Study
Kwangmin Oh, Kristen C. Dage, Alexey Bobrick +9
We present new multi-wavelength observations of two ultraluminous X-ray sources (ULXs) hosted by globular clusters (GCs) in the giant elliptical NGC 1399, focusing on CXO J0338318-…
The Most Rapidly Declining Type I Supernova 2019bkc/ATLAS19dqr
Ping Chen, Subo Dong, M. D. Stritzinger +21
We report observations of the hydrogen-deficient supernova (SN) 2019bkc/ATLAS19dqr. With B- and r-band decline between peak and 10 days post peak of Delta m_10(B)=5.24+/-0.07 mag a…
ASASSN-16ae: A Powerful White-Light Flare on an Early-L Dwarf
Sarah J. Schmidt, Benjamin J. Shappee, Jonathan Gagné +8
We report the discovery and classification of SDSS~J053341.43+001434.1 (SDSS0533), an early-L dwarf first discovered during a powerful magnitude flare observed as part…
The 10830 A He I Line Among M13 Red Giants
Graeme Smith, Andrea Dupree, Jay Strader
Two properties of Messier 13 are pertinent to the study of mass loss among metal-poor stars and the chemical evolution of globular clusters: (i) an extended blue horizontal branch,…
Evidence for Two Phases of Galaxy Formation from Radial Trends in the Globular Cluster System of NGC 1407
Duncan Forbes, Lee Spitler, Jay Strader +3
Here we present the colours of individual globular clusters (GCs) around the massive elliptical galaxy NGC 1407 out to a projected galactocentric radius of 140 kpc or 17 galaxy eff…
The SLUGGS Survey: The Assembly Histories of Individual Early-type Galaxies
Duncan A. Forbes, Aaron J. Romanowsky, Nicola Pastorello +5
Early-type (E and S0) galaxies may have assembled via a variety of different evolutionary pathways. Here we investigate these pathways by comparing the stellar kinematic properties…
OGLE-BLG504.12.201843: A possible extreme dwarf nova
Camille Landri, OndÅej Pejcha, MichaÅ Pawlak +5
We present the analysis of existing optical photometry and new optical spectroscopy of the candidate cataclysmic variable star OGLE-BLG504.12.201843. As was shown previously, this…
A census of dwarf galaxy satellites around LMC-mass galaxy NGC 2403
Jeffrey L. Carlin, David J. Sand, Burcin Mutlu-Pakdil +11
We present the first comprehensive census of the satellite population around a Large Magellanic Cloud (LMC) stellar-mass galaxy, as part of the Magellanic Analog Dwarf Companions a…
The SLUGGS Survey: Globular cluster system kinematics and substructure in NGC 4365
Christina Blom, Duncan A. Forbes, Jean P. Brodie +4
We present a kinematic analysis of the globular cluster (GC) system of the giant elliptical galaxy NGC 4365 and find several distinct kinematic substructures. This analysis is carr…
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…
Dynamical Modeling of CXOGBS J175553.2-281633: A 10 Hour Long Orbital Period Cataclysmic Variable
Sebastian Gomez, Manuel A. P. Torres, Peter G. Jonker +8
We present modeling of the long-term optical light curve and radial velocity curve of the binary stellar system CXOGBS J175553.2-281633, first detected in X-rays in the \textit{Cha…
A Deep Search for Prompt Radio Emission from Thermonuclear Supernovae with the Very Large Array
Laura Chomiuk, Alicia M. Soderberg, Roger A. Chevalier +10
Searches for circumstellar material around Type Ia supernovae (SNe Ia) are one of the most powerful tests of the nature of SN Ia progenitors, and radio observations provide a parti…
Hubble Space Telescope observations of globular cluster systems along the Hubble sequence of spiral galaxies
Paul Goudfrooij, Jay Strader, Laura Brenneman +3
We have studied the globular cluster (GC) systems of 7 giant, edge-on spiral galaxies using Hubble Space Telescope imaging in V and I. The galaxy sample covers the Hubble types Sa…
X-ray Spectroscopy of the gamma-ray Brightest Nova V906 Car (ASASSN-18fv)
Kirill V. Sokolovsky, Koji Mukai, Laura Chomiuk +15
Shocks in gamma-ray emitting classical novae are expected to produce bright thermal and non-thermal X-rays. We test this prediction with simultaneous NuSTAR and Fermi/LAT observati…
Slow Decline and Rise of the Broad [OIII] Emission Line in Globular Cluster Black Hole Candidate RZ2109
Kristen C. Dage, Stephen E. Zepf, Arash Bahramian +6
RZ2109 is the first of several extragalactic globular clusters shown to host an ultraluminous X-ray source. RZ2109 is particularly notable because optical spectroscopy shows it has…
The SLUGGS survey: Exploring the globular cluster systems of the Leo II group and their global relationships
Sreeja S. Kartha, Duncan A. Forbes, Adebusola B. Alabi +6
We present an investigation of the globular cluster (GC) systems of NGC 3607 and NGC 3608 as part of the ongoing SLUGGS survey. We use wide-field imaging data from the Subaru teles…
Probing Spectral Line Gradients Beyond One Effective Radius in NGC 3610
Justin Howell, Jean Brodie, Jay Strader +2
The outer region (0.75--1.25 r_e in the B-band) of the merger-remnant elliptical NGC 3610 is studied using extremely high signal to noise Keck spectra, with a supplementary spectru…
Radial distributions of sub-populations in the globular cluster M15: a more centrally concentrated primordial population
Soeren S. Larsen, Holger Baumgardt, Nate Bastian +3
We examine the radial distributions of stellar populations in the globular cluster (GC) M15, using HST/WFC3 photometry of red giants in the nitrogen-sensitive F343N-F555W color. Su…
Mapping the Dark Side with DEIMOS: Globular Clusters, X-ray Gas, and Dark Matter in the NGC 1407 Group
Aaron J. Romanowsky, Jay Strader, Lee R. Spitler +4
NGC 1407 is the central elliptical in a nearby evolved galaxy group apparently destined to become a cluster core. We use the kinematics of globular clusters to probe the dynamics a…
The first nova eruption in a novalike variable: YZ Ret as seen in X-rays and gamma-rays
Kirill V. Sokolovsky, Kwan-Lok Li, Raimundo Lopes de Oliveira +16
Peaking at 3.7 mag on 2020 July 11, YZ Ret was the second-brightest nova of the decade. The nova's moderate proximity (2.7 kpc from Gaia) provided an opportunity to explore its mul…
The Plane's The Thing: The Case for Wide-Fast-Deep Coverage of the Galactic Plane and Bulge
Jay Strader, Elias Aydi, Christopher Britt +21
We argue that the exclusion of the Galactic Plane and Bulge from the uniform wide-fast-deep (WFD) LSST survey cadence is fundamentally inconsistent with two of the main science dri…
A Search for Wandering Black Holes in the Milky Way with Gaia and DECaLS
Jenny E. Greene, Lachlan Lancaster, Yuan-Sen Ting +6
We present a search for "hyper-compact" star clusters in the Milky Way using a combination of Gaia and the Dark Energy Camera Legacy Survey (DECaLS). Such putative clusters, with s…
The SLUGGS Survey: globular clusters and the dark matter content of early-type galaxies
Duncan A. Forbes, Adebusola Alabi, Aaron J. Romanowsky +4
A strong correlation exists between the total mass of a globular cluster (GC) system and the virial halo mass of the host galaxy. However, the total halo mass in this correlation i…
Multiwavelength Evidence for Two New Candidate Transitional Millisecond Pulsars in the Sub-luminous Disk State: 4FGL J0639.1--8009 and 4FGL J1824.2+1231
Rebecca Kyer, Subhroja Roy, Jay Strader +4
We report the discovery of two new Galactic accreting compact objects consistent with the respective positions of the unassociated Fermi-LAT gamma-ray sources 4FGL J0639.1--8009 an…
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…
Optimizing Kilonova Searches: A Case Study of the Type IIb SN 2025ulz in the Localization Volume of the Low-Significance Gravitational Wave Event S250818k
Noah Franz, Bhagya Subrayan, Charles D. Kilpatrick +54
Kilonovae, the ultraviolet/optical/infrared counterparts to binary neutron star mergers, are an exceptionally rare class of transients. Optical follow-up campaigns are plagued by c…
The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9
Arash Bahramian, Craig O. Heinke, Vlad Tudor +9
47 Tuc X9 is a low mass X-ray binary (LMXB) in the globular cluster 47 Tucanae, and was previously thought to be a cataclysmic variable. However, Miller-Jones et al. (2015) recentl…
PSR J1306--40: An X-ray Luminous Redback with an Evolved Companion
Samuel J. Swihart, Jay Strader, Laura Chomiuk +1
PSR J1306--40 is a millisecond pulsar binary with a non-degenerate companion in an unusually long 1.097 day orbit. We present new optical photometry and spectroscopy of this…
Fermi-LAT Observations of V549 Vel 2017: a Sub-Luminous Gamma-Ray Nova?
Kwan-Lok Li, Franz-Josef Hambsch, Ulisse Munari +4
We report on the Fermi-LAT detection (with ~5.7 sigma significance) as well as the multi-wavelength analysis of the 2017 nova eruption V549 Vel. Unlike the recent shock-powered nov…
Orbital Dynamics of Candidate Transitional Millisecond Pulsar 3FGL J1544.6-1125: An unusually face-on system
Christopher T. Britt, Jay Strader, Laura Chomiuk +4
We present the orbital solution for the donor star of the candidate transitional millisecond pulsar 3FGL J1544.6-1125, currently observed as an accreting low-mass X-ray binary. The…
Resolved Dwarf Galaxy Searches within ~5 Mpc with the Vera Rubin Observatory and Subaru Hyper Suprime-Cam
Burçin Mutlu-Pakdil, David J. Sand, Denija CrnojeviÄ +7
We present a preview of the faint dwarf galaxy discoveries that will be possible with the Vera C. Rubin Observatory and Subaru Hyper Suprime-Cam in the next decade. In this work, w…
The Megasecond Chandra X-Ray Visionary Project Observation of NGC 3115 (II): properties of point sources
Dacheng Lin, Jimmy A. Irwin, Ka-wah Wong +7
We have carried out an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115, using the Megasecond Chandra X-Ray Visionary Project obs…
Hubble Space Telescope Photometry of Globular Clusters in M81
Julie B. Nantais, John P. Huchra, Andreas Zezas +2
We perform aperture photometry and profile fitting on 419 globular cluster (GC) candidates with mV \leq 23 mag identified in Hubble Space Telescope Advanced Camera for Surveys BVI…
Ultraluminous X-ray Sources in Seven Edge-On Spiral Galaxies
Kristen C. Dage, Noah Vowell, Erica Thygesen +8
We investigate a sample of seven edge-on spiral galaxies using Chandra observations. Edge-on spiral galaxies allow us to clearly separate source associated with their star-forming…
The MAVERIC Survey: Still No Evidence for Accreting Intermediate-mass Black Holes in Globular Clusters
Evangelia Tremou, Jay Strader, Laura Chomiuk +8
We present the results of an ultra-deep, comprehensive radio continuum survey for the accretion signatures of intermediate-mass black holes in globular clusters. The sample, imaged…
The Gravity Collective: A Search for the Electromagnetic Counterpart to the Neutron Star-Black Hole Merger GW190814
Charles D. Kilpatrick, David A. Coulter, Iair Arcavi +79
We present optical follow-up imaging obtained with the Katzman Automatic Imaging Telescope, Las Cumbres Observatory Global Telescope Network, Nickel Telescope, Swope Telescope, and…
The Faint Satellite System of NGC 253: Insights into Low-Density Environments and No Satellite Plane
Burçin Mutlu-Pakdil, David J. Sand, Denija CrnojeviÄ +12
We have conducted a systematic search around the Milky Way (MW) analog NGC 253 (D=3.5 Mpc), as a part of the Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) - a Magella…
Star Clusters in M31: V. Internal Dynamical Trends: Some Troublesome, Some Reassuring
Jay Strader, Nelson Caldwell, Anil Seth
We present internal velocity dispersions and precise radial velocities for 200 globular clusters (GCs) in M31 that are derived using new high-resolution spectra from MMT/Hectochell…
The SLUGGS Survey: Trails of SLUGGS galaxies in a modified spin-ellipticity diagram
Sabine Bellstedt, Alister W. Graham, Duncan A. Forbes +3
We present radial tracks for four early-type galaxies with embedded intermediate-scale discs in a modified spin-ellipticity diagram. Here, each galaxy's spin and ellipticity profil…
Integrated Colours of Milky Way Globular Clusters and Horizontal Branch Morphology
Graeme H. Smith, Jay Strader
Broadband colours are often used as metallicity proxies in the study of extragalactic globular clusters. A common concern is the effect of variations in horizontal branch (HB) morp…
AGN Feedback in the Hot Halo of NGC 4649
Alessandro Paggi, Giuseppina Fabbiano, Dong-Woo Kim +4
Using the deepest available observations of NGC 4649 we find strong evidences of cavities, ripples and ring like structures in the hot interstellar medium (ISM)…
Small scatter and nearly-isothermal mass profiles to four half-light radii from two-dimensional stellar dynamics of early-type galaxies
Michele Cappellari, Aaron J. Romanowsky, Jean P. Brodie +9
We study the total mass-density profile for a sample of 14 fast-rotator early-type galaxies (stellar masses ). We combine observations from the SLUGG…
Kinematics and simulations of the stellar stream in the halo of the Umbrella Galaxy
Caroline Foster, Hanni Lux, Aaron J. Romanowsky +9
We study the dynamics of faint stellar substructures around the Umbrella Galaxy, NGC 4651, which hosts a dramatic system of streams and shells formed through the tidal disruption o…
The faint globular cluster in the dwarf galaxy Andromeda I
Nelson Caldwell, Jay Strader, David J. Sand +2
Observations of globular clusters in dwarf galaxies can be used to study a variety of topics, including the structure of dark matter halos and the history of vigorous star formatio…
1FGL J0523.5-2529: A New Probable Gamma-ray Pulsar Binary
Jay Strader, Laura Chomiuk, Eda Sonbas +4
We report optical photometric and SOAR spectroscopic observations of an X-ray source found within the localization error of the Fermi-LAT unidentified gamma-ray source J0523.5-2529…
The X-ray Source Population of the Metal-Rich Globular Cluster NGC 6528
Bernard Leal, Kwangmin Oh, Jay Strader +4
We present the first study of the X-ray sources in one of the most metal-rich globular clusters in the Galaxy, NGC 6528. Using relatively deep (66 ksec) archival imaging from the C…
The MAVERIC survey: A catalogue of radio sources in southern globular clusters from the Australia Telescope Compact Array
Vlad Tudor, James C. A. Miller-Jones, Jay Strader +11
Radio continuum observations offer a new window on compact objects in globular clusters compared to typical X-ray or optical studies. As part of the MAVERIC survey, we have used th…
Discovery of a Redback Millisecond Pulsar Candidate: 3FGL J0212.1+5320
Kwan-Lok Li, Albert K. H. Kong, Xian Hou +4
We present a multi-wavelength study of the unidentified Fermi object, 3FGL J0212.1+5320. Within the 95% error ellipse, Chandra detects a bright X-ray source (i.e., F(0.5-7keV) = 1.…
A Blue Tilt in the Globular Cluster System of the Milky Way-like Galaxy NGC 5170
Duncan Forbes, Lee Spitler, William Harris +4
Here we present HST/ACS imaging, in the B and I bands, of the edge-on Sb/Sc galaxy NGC 5170. Excluding the central disk region region, we detect a 142 objects with colours and size…
The Globular Cluster Population of NGC 7457: Clues to the Evolution of Field S0 Galaxies
Jonathan R. Hargis, Katherine L. Rhode, Jay Strader +1
In this paper we present the results of a wide-field imaging study of the globular cluster (GC) system of the field S0 galaxy NGC 7457. To derive the global properties of the GC sy…
Space-Based UV/Optical Wide-Field Imaging and Spectroscopy: Near-Field Cosmology and Galaxy Evolution Using Globular Clusters in Nearby Galaxies
Paul Goudfrooij, Jean Brodie, Rupali Chandar +7
Star formation plays a central role in the evolution of galaxies and of the Universe as a whole. Studies of star-forming regions in the local universe have shown that star formatio…
The Blue Supergiant Progenitor of the Supernova Imposter AT~2019krl
Jennifer E. Andrews, Jacob E. Jencson, Schuyler D. Van Dyk +20
Extensive archival \textit{Hubble Space Telescope}, \textit{Spitzer Space Telescope}, and Large Binocular Telescope imaging of the recent intermediate-luminosity transient, AT~2019…
A Radio Emission Analysis of Classical Nova V351 Pup (1991)
Carolyn N. Wendeln, Laura Chomiuk, Thomas Finzell +2
Previously, Nova Puppis 1991 (V351 Pup) was measured to host one of the most massive ejections claimed in the literature. Multi-frequency radio detections from one epoch were publi…
The SLUGGS Survey: Measuring globular cluster ages using both photometry and spectroscopy
Christopher Usher, Jean P. Brodie, Duncan A. Forbes +4
Globular cluster ages provide both an important test of models of globular cluster formation and a powerful method to constrain the assembly history of galaxies. Unfortunately, mea…
The AIMSS Project I: Bridging the Star Cluster - Galaxy Divide
Mark A. Norris, Sheila J. Kannappan, Duncan A. Forbes +15
We describe the structural and kinematic properties of the first compact stellar systems discovered by the AIMSS project. These spectroscopically confirmed objects have sizes ($\si…
The SLUGGS survey: Globular cluster stellar population trends from weak absorption lines in stacked spectra
Christopher Usher, Duncan A. Forbes, Jean P. Brodie +7
As part of the SLUGGS survey, we stack 1137 Keck DEIMOS spectra of globular clusters from 10 galaxies to study their stellar populations in detail. The stacked spectra have median…