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Full-Text Articles in Astrophysics and Astronomy
Wallaby Pilot Survey: Hydra Cluster Galaxies Uv And H I Morphometrics, Benne W. Holwerda, Frank Bigiel, Albert Bosma, Helene M. Courtois, Nathan Deg, Helga Dénes, Ahmed Elagali, Bi-Qing For, Baerbel Koribalski, Denis A. Leahy, Karen Lee-Waddell, Ángel R. López-Sánchez, Se-Heon Oh, Tristan N. Reynolds, Jonghwan Rhee, Kristine Spekkens, Jing Wang, Tobias Westmeier, O Ivy Wong
Wallaby Pilot Survey: Hydra Cluster Galaxies Uv And H I Morphometrics, Benne W. Holwerda, Frank Bigiel, Albert Bosma, Helene M. Courtois, Nathan Deg, Helga Dénes, Ahmed Elagali, Bi-Qing For, Baerbel Koribalski, Denis A. Leahy, Karen Lee-Waddell, Ángel R. López-Sánchez, Se-Heon Oh, Tristan N. Reynolds, Jonghwan Rhee, Kristine Spekkens, Jing Wang, Tobias Westmeier, O Ivy Wong
Faculty Scholarship
Galaxy morphology in atomic hydrogen (H I) and in the ultraviolet (UV) are closely linked. This has motivated their combined use to quantify morphology over the full H I disc for both H I and UV imaging. We apply galaxy morphometrics: concentration, asymmetry, gini, M20 and multimode-intensity-deviation statistics to the first moment-0 maps of the WALLABY Survey of galaxies in the hydra cluster centre. Taking advantage of this new H I survey, we apply the same morphometrics over the full H I extent on archival GALEX FUV and NUV data to explore how well H I truncated, extended ultraviolet …
Dark Matter And No Dark Matter: On The Halo Mass Of Ngc 1052, Duncan Forbes, Adebusola Alabi, Jean Brodie, Aaron Romanowsky
Dark Matter And No Dark Matter: On The Halo Mass Of Ngc 1052, Duncan Forbes, Adebusola Alabi, Jean Brodie, Aaron Romanowsky
Faculty Publications
The NGC 1052 group, and in particular the discovery of two ultra-diffuse galaxies with very low internal velocity dispersions, has been the subject of much attention recently. Here we present radial velocities for a sample of 77 globular clusters associated with NGC 1052 obtained on the Keck telescope. Their mean velocity and velocity dispersion are consistent with that of the host galaxy. Using a simple tracer mass estimator, we infer the enclosed dynamical mass and dark matter fraction of NGC 1052. Extrapolating our measurements with a Navarro–Frenk–White (NFW) mass profile we infer a total halo mass of 6.2(±0.2) × 1012 …
Spatially Resolved Stellar Populations And Kinematics With Kcwi: Probing The Assembly History Of The Massive Early-Type Galaxy Ngc 1407, Anna Ferré-Mateu, Duncan Forbes, Richard Mcdermid, Aaron Romanowsky, Jean Brodie
Spatially Resolved Stellar Populations And Kinematics With Kcwi: Probing The Assembly History Of The Massive Early-Type Galaxy Ngc 1407, Anna Ferré-Mateu, Duncan Forbes, Richard Mcdermid, Aaron Romanowsky, Jean Brodie
Faculty Publications
Using the newly commissioned Keck Cosmic Web Imager (KCWI) instrument on the Keck II telescope, we analyze the stellar kinematics and stellar populations of the well-studied massive early-type galaxy (ETG) NGC 1407. We obtained high signal-to-noise integral field spectra for a central and an outer (around one effective radius toward the southeast direction) pointing with integration times of just 600 s and 2400 s, respectively. We confirm the presence of a kinematically distinct core also revealed by VLT/MUSE data of the central regions. While NGC 1407 was previously found to have stellar populations characteristic of massive ETGs (with radially constant …
Still Missing Dark Matter: Kcwi High-Resolution Stellar Kinematics Of Ngc1052-Df2, Shany Danieli, Pieter Van Dokkum, Charlie Conroy, Roberto Abraham, Aaron Romanowsky
Still Missing Dark Matter: Kcwi High-Resolution Stellar Kinematics Of Ngc1052-Df2, Shany Danieli, Pieter Van Dokkum, Charlie Conroy, Roberto Abraham, Aaron Romanowsky
Faculty Publications
The velocity dispersion of the ultra diffuse galaxy NGC1052-DF2 was found to be σgc = 7.8 +5.2/-2.2 km s−1, much lower than expected from the stellar mass–halo mass relation and nearly identical to the expected value from the stellar mass alone. This result was based on the radial velocities of 10 luminous globular clusters that were assumed to be associated with the galaxy. A more precise measurement is possible from high-resolution spectroscopy of the diffuse stellar light. Here we present an integrated spectrum of the diffuse light of NGC1052-DF2 obtained with the Keck Cosmic Web Imager (KCWI), with an instrumental …
The Extended Planetary Nebula Spectrograph (Epn.S) Early-Type Galaxy Survey: The Kinematic Diversity Of Stellar Halos And The Relation Between Halo Transition Scale And Stellar Mass, C. Pulsoni, O. Gerhard, M. Arnaboldi, L. Coccato, A. Longobardi, N. Napolitano, E. Moylan, C. Narayan, V. Gupta, A. Burkert, M. Capaccioli, A. Chies-Santos, A. Cortesi, K. Freeman, K. Kuijken, M. Merrifield, Aaron Romanowsky, C. Tortora
The Extended Planetary Nebula Spectrograph (Epn.S) Early-Type Galaxy Survey: The Kinematic Diversity Of Stellar Halos And The Relation Between Halo Transition Scale And Stellar Mass, C. Pulsoni, O. Gerhard, M. Arnaboldi, L. Coccato, A. Longobardi, N. Napolitano, E. Moylan, C. Narayan, V. Gupta, A. Burkert, M. Capaccioli, A. Chies-Santos, A. Cortesi, K. Freeman, K. Kuijken, M. Merrifield, Aaron Romanowsky, C. Tortora
Faculty Research, Scholarly, and Creative Activity
Context. In the hierarchical two-phase formation scenario, the halos of early type galaxies (ETGs) are expected to have different physical properties from the galaxies’ central regions.Aims. The ePN.S survey characterizes the kinematic properties of ETG halos using planetary nebulae (PNe) as tracers, overcoming the limitations of absorption line spectroscopy at low surface brightness.Methods. We present two-dimensional velocity and velocity dispersion fields for 33 ETGs, including fast (FRs) and slow rotators (SRs). The velocity fields were reconstructed from the measured PN velocities using an adaptive kernel procedure validated with simulations, and extend to a median of 5.6 effective radii (Re). We …
Wide-Field Kinematics Of Globular Clusters In The Leo I Group (Corrigendum), G. Bergond, S. Zepf, Aaron Romanowsky, R. Sharples, K. Rhode
Wide-Field Kinematics Of Globular Clusters In The Leo I Group (Corrigendum), G. Bergond, S. Zepf, Aaron Romanowsky, R. Sharples, K. Rhode
Faculty Publications
No abstract provided.
Chromodynamical Analysis Of Lenticular Galaxies Using Globular Clusters And Planetary Nebulae, Emilio Zanatta, Arianna Cortesi, Ana Chies-Santos, Duncan Forbes, Aaron Romanowsky, Adebusola Alabi, Lodovico Coccato, Claudia Mendes De Oliveira, Jean Brodie, Michael Merrifield
Chromodynamical Analysis Of Lenticular Galaxies Using Globular Clusters And Planetary Nebulae, Emilio Zanatta, Arianna Cortesi, Ana Chies-Santos, Duncan Forbes, Aaron Romanowsky, Adebusola Alabi, Lodovico Coccato, Claudia Mendes De Oliveira, Jean Brodie, Michael Merrifield
Faculty Publications
Recovering the origins of lenticular galaxies can shed light on the understanding of galaxy and compare them with the kinematics of planetary nebulae (PNe). The PNe and GC data come from the Planetary Nebulae Spectrograph and the SLUGGS Surveys. Through photometric spheroid-disc decomposition and PNe kinematics. we find the probability for a given GC to belong to either the spheroid or the disc of its host galaxy or be rejected from the model. We find that there is no correlation between the components that the GCs are likely to belong to and their colours. Particularly, for NGC 2768, we find …
Origins Of Ultradiffuse Galaxies In The Coma Cluster – Ii. Constraints From Their Stellar Populations, Anna Ferre-Mateu, Adebusola Alabi, Duncan Forbes, Aaron Romanowsky, Jean Brodie, Viraj Pandya, Ignacio Mart´In-Navarro, Sabine Bellstedt, Asher Wasserman, Maria Stone, Nobuhiro Okabe
Origins Of Ultradiffuse Galaxies In The Coma Cluster – Ii. Constraints From Their Stellar Populations, Anna Ferre-Mateu, Adebusola Alabi, Duncan Forbes, Aaron Romanowsky, Jean Brodie, Viraj Pandya, Ignacio Mart´In-Navarro, Sabine Bellstedt, Asher Wasserman, Maria Stone, Nobuhiro Okabe
Faculty Publications
In this second paper of the series we study, with new Keck/DEIMOS spectra, the stellar populations of seven spectroscopically confirmed ultradiffuse galaxies (UDGs) in the Coma cluster. We find intermediate to old ages (∼7 Gyr), low metallicities ([Z/H] ∼ −0.7 dex) and mostly supersolar abundance patterns ([Mg/Fe] ∼ 0.13 dex). These properties are similar to those of low-luminosity (dwarf) galaxies inhabiting the same area in the cluster and are mostly consistent with being the continuity of the stellar mass scaling relations of more massive galaxies. These UDGs’ star formation histories imply a relatively recent infall into the Coma cluster, consistent …
Origins Of Ultradiffuse Galaxies In The Coma Cluster – I. Constraints From Velocity Phase Space, Adebusola Alabi, Anna Ferré-Mateu, Aaron Romanowsky, Jean Brodie, Duncan Forbes, Asher Wasserman, Sabine Bellstedt, Ignacio Martín-Navarro, Viraj Pandya, Maria Stone, Nobuhiro Okabe
Origins Of Ultradiffuse Galaxies In The Coma Cluster – I. Constraints From Velocity Phase Space, Adebusola Alabi, Anna Ferré-Mateu, Aaron Romanowsky, Jean Brodie, Duncan Forbes, Asher Wasserman, Sabine Bellstedt, Ignacio Martín-Navarro, Viraj Pandya, Maria Stone, Nobuhiro Okabe
Faculty Publications
We use Keck/DEIMOS spectroscopy to confirm the cluster membership of 16 ultradiffuse galaxies (UDGs) in the Coma cluster, bringing the total number of spectroscopically confirmed UDGs from the Yagi et al. (Y16) catalogue to 25. We also identify a new cluster background UDG, confirming that most (∼95 per cent) of the UDGs in the Y16 catalogue belong to the Coma cluster. In this pilot study of Coma UDGs in velocity phase space, we find evidence of a diverse origin for Coma cluster UDGs, similar to normal dwarf galaxies. Some UDGs in our sample are consistent with being late infalls into …
The Sluggs Survey: The Inner Dark Matter Density Slope Of The Massive Elliptical Galaxy Ngc 1407, Asher Wasserman, Aaron Romanowsky, Jean Brodie, Pieter Van Dokkum, Charlie Conroy, Alexa Villaume, Duncan Forbes, Jay Strader, Adebusola Alabi, Sabine Bellstedt
The Sluggs Survey: The Inner Dark Matter Density Slope Of The Massive Elliptical Galaxy Ngc 1407, Asher Wasserman, Aaron Romanowsky, Jean Brodie, Pieter Van Dokkum, Charlie Conroy, Alexa Villaume, Duncan Forbes, Jay Strader, Adebusola Alabi, Sabine Bellstedt
Faculty Publications
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 systems. Two major challenges in such models are the degeneracy between the stellar mass and the dark matter halo profiles, and the degeneracy between the orbital anisotropy of the tracer population and the total mass causing the observed motions. We address the first issue by using new measurements of the mass-to-light ratio profile from stellar population constraints that include a radially varying initial mass function. To mitigate the mass–anisotropy degeneracy, we make use …
A Deficit Of Dark Matter From Jeans Modeling Of The Ultra-Diffuse Galaxy Ngc 1052-Df2, Asher Wasserman, Aaron Romanowsky, Jean Brodie, Pieter Van Dokkum, Charlie Conroy, Roberto Abraham, Yotam Cohen, Shany Danieli
A Deficit Of Dark Matter From Jeans Modeling Of The Ultra-Diffuse Galaxy Ngc 1052-Df2, Asher Wasserman, Aaron Romanowsky, Jean Brodie, Pieter Van Dokkum, Charlie Conroy, Roberto Abraham, Yotam Cohen, Shany Danieli
Faculty Publications
The discovery of the ultra-diffuse galaxy NGC 1052-DF2 and its peculiar population of star clusters has raised new questions about the connections between galaxies and dark matter (DM) halos at the extremes of galaxy formation. In light of debates over the measured velocity dispersion of its star clusters and the associated mass estimate, we constrain mass models of DF2 using its observed kinematics with a range of priors on the halo mass. Models in which the galaxy obeys a standard stellar-halo mass relation are in tension with the data and also require a large central density core. Better fits are …
A 3.5 Million Solar Masses Black Hole In The Centre Of The Ultracompact Dwarf Galaxy Fornax Ucd3, Anton Afanasiev, Igor Chilingarian, Steffen Mieske, Karina Voggel, Arianna Picotti, Michael Hilker, Anil Seth, Nadine Neumayer, Matthias Frank, Aaron Romanowsky, George Hau, Holger Baumgardt, Christopher Ahn, Jay Strader, Mark Den Brok, Richard Mcdermid, Lee Spitler, Jean Brodie, Jonelle Walsh
A 3.5 Million Solar Masses Black Hole In The Centre Of The Ultracompact Dwarf Galaxy Fornax Ucd3, Anton Afanasiev, Igor Chilingarian, Steffen Mieske, Karina Voggel, Arianna Picotti, Michael Hilker, Anil Seth, Nadine Neumayer, Matthias Frank, Aaron Romanowsky, George Hau, Holger Baumgardt, Christopher Ahn, Jay Strader, Mark Den Brok, Richard Mcdermid, Lee Spitler, Jean Brodie, Jonelle Walsh
Faculty Publications
The origin of ultracompact dwarfs (UCDs), a class of compact stellar systems discovered two decades ago, still remains a matter of debate. Recent discoveries of central supermassive black holes in UCDs likely inherited from their massive progenitor galaxies provide support for the tidal stripping hypothesis. At the same time, on statistical grounds, some massive UCDs might be representatives of the high luminosity tail of the globular cluster luminosity function. Here we present a detection of a 3.3+1.4−1.2×106M⊙ black hole (1σ uncertainty) in the centre of the UCD3 galaxy in the Fornax cluster, which corresponds to 4 per cent of its …
The Sluggs Survey: A Comparison Of Total-Mass Profiles Of Early-Type Galaxies From Observations And Cosmological Simulations, To ∼4 Effective Radii, Sabine Bellstedt, Duncan Forbes, Aaron Romanowsky, Rhea-Silvia Remus, Adam Stevens, Jean Brodie, Adriano Poci, Richard Mcdermid, Adebusola Alabi, Leonie Chevalier, Caitlin Adams, Anna Ferré-Mateu, Asher Wasserman, Viraj Pandya
The Sluggs Survey: A Comparison Of Total-Mass Profiles Of Early-Type Galaxies From Observations And Cosmological Simulations, To ∼4 Effective Radii, Sabine Bellstedt, Duncan Forbes, Aaron Romanowsky, Rhea-Silvia Remus, Adam Stevens, Jean Brodie, Adriano Poci, Richard Mcdermid, Adebusola Alabi, Leonie Chevalier, Caitlin Adams, Anna Ferré-Mateu, Asher Wasserman, Viraj Pandya
Faculty Publications
We apply the Jeans Anisotropic Multi-Gaussian Expansion dynamical modelling method to SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey data of early-type galaxies in the stellar mass range 1010 < M*/M⊙ < 1011.6 that cover a large radial range of 0.1–4.0 effective radii. We combine SLUGGS and ATLAS3D data sets to model the total-mass profiles of a sample of 21 fast-rotator galaxies, utilizing a hyperparameter method to combine the two independent data sets. The total-mass density profile slope values derived for these galaxies are consistent with those measured in the inner regions of galaxies by other studies. Furthermore, the total-mass density slopes (γtot) appear to be universal over this broad stellar mass range, with an average value of γtot = −2.24 ± 0.05 , i.e. slightly steeper than isothermal. We compare our results to model galaxies from the Magneticum and EAGLE cosmological hydrodynamic simulations, in order to probe the mechanisms that are responsible for varying total-mass density profile slopes. The simulated-galaxy slopes are shallower than the observed values by ∼0.3–0.5, indicating that the physical processes shaping the mass distributions of galaxies in cosmological simulations are still incomplete. For galaxies with M* > 1010.7 M⊙ in the Magneticum simulations, we identify a significant anticorrelation between total-mass density profile slopes and the fraction of stellar mass formed ex situ (i.e. accreted), whereas this anticorrelation is weaker for lower stellar masses, implying that the measured total-mass density slopes for low-mass galaxies are less likely to be determined by merger activity.
Upper Limits On The Presence Of Central Massive Black Holes In Two Ultra-Compact Dwarf Galaxies In Centaurus A, Karina Voggel, Anil Seth, Nadine Neumayer, Steffen Mieske, Igor Chilingarian, Christopher Ahn, Holger Baumgardt, Michael Hilker, Dieu Nguyen, Aaron J. Romanowsky, Jonelle Walsh, Mark Den Brok, Jay Strader
Upper Limits On The Presence Of Central Massive Black Holes In Two Ultra-Compact Dwarf Galaxies In Centaurus A, Karina Voggel, Anil Seth, Nadine Neumayer, Steffen Mieske, Igor Chilingarian, Christopher Ahn, Holger Baumgardt, Michael Hilker, Dieu Nguyen, Aaron J. Romanowsky, Jonelle Walsh, Mark Den Brok, Jay Strader
Faculty Publications
The recent discovery of massive black holes (BHs) in the centers of high-mass ultra-compact dwarf galaxies (UCDs) suggests that at least some are the stripped nuclear star clusters of dwarf galaxies. We present the first study that investigates whether such massive BHs, and therefore stripped nuclei, also exist in low-mass (M < 107 M ⊙) UCDs. We constrain the BH masses of two UCDs located in Centaurus A (UCD 320 and UCD 330) using Jeans modeling of the resolved stellar kinematics from adaptive optics data obtained with the SINFONI integral field spectrograph at the Very Large Telescope (VLT/SINFONI). No massive BHs …
Galaxy And Mass Assembly (Gama): Small-Scale Anisotropic Galaxy Clustering And The Pairwise Velocity Dispersion Of Galaxies, J. Loveday, L. Christodoulou, P. Norberg, J. A. Peacock, I. K. Baldry, J. Bland-Hawthorn, M. J.I. Brown, M. Colless, S. P. Driver, Benne W. Holwerda, A. M. Hopkins, P. R. Kafle, J. Liske, A. R. Lopez-Sanchez, E. N. Taylor
Galaxy And Mass Assembly (Gama): Small-Scale Anisotropic Galaxy Clustering And The Pairwise Velocity Dispersion Of Galaxies, J. Loveday, L. Christodoulou, P. Norberg, J. A. Peacock, I. K. Baldry, J. Bland-Hawthorn, M. J.I. Brown, M. Colless, S. P. Driver, Benne W. Holwerda, A. M. Hopkins, P. R. Kafle, J. Liske, A. R. Lopez-Sanchez, E. N. Taylor
Faculty Scholarship
The galaxy pairwise velocity dispersion (PVD) can provide important tests of non-standard gravity and galaxy formation models. We describe measurements of the PVD of galaxies in the Galaxy and Mass Assembly (GAMA) survey as a function of projected separation and galaxy luminosity. Due to the faint magnitude limit (r < 19.8) and highly complete spectroscopic sampling of the GAMA survey, we are able to reliably measure the PVD to smaller scales (r⊥ = 0.01 h -1 Mpc) than previous work. The measured PVD at projected separations r⊥ < 1 h -1 Mpc increases near monotonically with increasing luminosity from σ12 ≈ 200 km s-1 at Mr = -17 mag to σ12 ≈ 600 km s-1 at Mr ≈ -22 mag. Analysis of the Gonzalez-Perez et al. (2014) GALFORM semi-analytic model yields no such trend of PVD with luminosity: the model overpredicts the PVD for faint galaxies. This is most likely a result of the model placing too many low-luminosity galaxies in massive haloes.
On The Formation Mechanisms Of Compact Elliptical Galaxies, Anna Ferré-Mateu, Duncan Forbes, Aaron Romanowsky, Joachim Janz, Christopher Dixon
On The Formation Mechanisms Of Compact Elliptical Galaxies, Anna Ferré-Mateu, Duncan Forbes, Aaron Romanowsky, Joachim Janz, Christopher Dixon
Faculty Publications
In order to investigate the formation mechanisms of the rare compact elliptical (cE) galaxies, we have compiled a sample of 25 cEs with good SDSS spectra, covering a range of stellar masses, sizes and environments. They have been visually classified according to the interaction with their host, representing different evolutionary stages. We have included clearly disrupted galaxies, galaxies that despite not showing signs of interaction are located close to a massive neighbour (thus are good candidates for a stripping process), and cEs with no host nearby. For the latter, tidal stripping is less likely to have happened and instead they …
The Sluggs Survey: Trails Of Sluggs Galaxies In A Modified Spin-Ellipticity Diagram, Sabine Bellstedt, Alister Graham, Duncan Forbes, Aaron Romanowsky, Jean Brodie, Jay Strader
The Sluggs Survey: Trails Of Sluggs Galaxies In A Modified Spin-Ellipticity Diagram, Sabine Bellstedt, Alister Graham, Duncan Forbes, Aaron Romanowsky, Jean Brodie, Jay Strader
Faculty Publications
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 profiles are shown as a radial track, as opposed to a single, flux-weighted aperture-dependent value as is common in the literature. The use of a single ellipticity and spin parameter is inadequate to capture the basic nature of these galaxies, which transition from fast to slow rotation as one moves to larger radii where the disc ceases to dominate. After peaking, the four galaxy's radial tracks feature a downturn in both ellipticity and spin with increasing radius, …
The Sluggs Survey: Using Extended Stellar Kinematics To Disentangle The Formation Histories Of Low-Mass S0 Galaxies, Sabine Bellstedt, Duncan Forbes, Caroline Foster, Aaron Romanowsky, Jean Brodie, Nicola Pastorello, Adebusola Alabi, Alexa Villaume
The Sluggs Survey: Using Extended Stellar Kinematics To Disentangle The Formation Histories Of Low-Mass S0 Galaxies, Sabine Bellstedt, Duncan Forbes, Caroline Foster, Aaron Romanowsky, Jean Brodie, Nicola Pastorello, Adebusola Alabi, Alexa Villaume
Faculty Publications
We utilize 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 GalaxieS (SLUGGS) survey. In this paper, we focus on some of the lowest stellar mass lenticular galaxies within this survey, namely NGC 2549, NGC 4474, NGC 4459 and NGC 7457, performing detailed kinematic analyses out to large radial distances of ∼2–3 effective radii. For NGC 2549, we present the first analysis of data taken with the SuperSKiMS (Stellar Kinematics from Multiple Slits) technique. To better probe kinematic variations in the outskirts of the …
Detection Of Supermassive Black Holes In Two Virgo Ultracompact Dwarf Galaxies, Christopher Ahn, Anil Seth, Mark Den Brok, Jay Strader, Holger Baumgardt, Remco Van Den Bosch, Igor Chilingarian, Matthias Frank, Michael Hilker, Richard Mcdermid, Steffen Mieske, Aaron Romanowsky, Lee Spitler, Jean Brodie, Nadine Neumayer, Jonelle Walsh
Detection Of Supermassive Black Holes In Two Virgo Ultracompact Dwarf Galaxies, Christopher Ahn, Anil Seth, Mark Den Brok, Jay Strader, Holger Baumgardt, Remco Van Den Bosch, Igor Chilingarian, Matthias Frank, Michael Hilker, Richard Mcdermid, Steffen Mieske, Aaron Romanowsky, Lee Spitler, Jean Brodie, Nadine Neumayer, Jonelle Walsh
Faculty Publications
No abstract provided.
A Discrete Chemo-Dynamical Model Of The Giant Elliptical Galaxy Ngc 5846: Dark Matter Fraction, Internal Rotation, And Velocity Anisotropy Out To Six Effective Radii, Ling Zhu, Aaron Romanowsky, Glenn Van De Ven, R. Long, Laura Watkins, Vincenzo Pota, Nicola Napolitano, Duncan Forbes, Jean Brodie, Caroline Foster
A Discrete Chemo-Dynamical Model Of The Giant Elliptical Galaxy Ngc 5846: Dark Matter Fraction, Internal Rotation, And Velocity Anisotropy Out To Six Effective Radii, Ling Zhu, Aaron Romanowsky, Glenn Van De Ven, R. Long, Laura Watkins, Vincenzo Pota, Nicola Napolitano, Duncan Forbes, Jean Brodie, Caroline Foster
Faculty Publications
We construct a suite of discrete chemo-dynamical models of the giant elliptical galaxy NGC 5846. These models are a powerful tool to constrain both the mass distribution and internal dynamics of multiple tracer populations. We use Jeans models to simultaneously fit stellar kinematics within the effective radius Re, planetary nebula (PN) radial velocities out to 3 Re, and globular cluster (GC) radial velocities and colours out to 6 Re. The best-fitting model is a cored dark matter halo which contributes ∼10 per cent of the total mass within 1 Re, and 67 per cent ± 10 per cent within 6 …
The Sluggs Survey: The Mass Distribution In Early-Type Galaxies Within Five Effective Radii And Beyond, Adebusola Alabi, Duncan Forbes, Aaron Romanowsky, Jean Brodie, Jay Strader, Joachim Janz, Vincenzo Pota, Nicola Pastorello, Christopher Usher, Lee Spitler, Caroline Foster, Zachary Jennings, Alexa Villaume, Sreeja Kartha
The Sluggs Survey: The Mass Distribution In Early-Type Galaxies Within Five Effective Radii And Beyond, Adebusola Alabi, Duncan Forbes, Aaron Romanowsky, Jean Brodie, Jay Strader, Joachim Janz, Vincenzo Pota, Nicola Pastorello, Christopher Usher, Lee Spitler, Caroline Foster, Zachary Jennings, Alexa Villaume, Sreeja Kartha
Faculty Publications
We study mass distributions within and beyond 5 effective radii (Re) in 23 early-type galaxies from the SAGES Legacy Unifying Globulars and Galaxies Survey, using their globular cluster (GC) kinematic data. The data are obtained with Keck/DEep Imaging Multi-Object Spectrograph, and consist of line-of-sight velocities for ∼3500 GCs, measured with a high precision of ∼15 km s−1 per GC and extending out to ∼13 Re. We obtain the mass distribution in each galaxy using the tracer mass estimator of Watkins et al. and account for kinematic substructures, rotation of the GC systems and galaxy flattening in our mass estimates. The …
The Sluggs Survey: The Assembly Histories Of Individual Early-Type Galaxies, Duncan Forbes, Aaron Romanowsky, Nicola Pastorello, Caroline Foster, Jean Brodie, Jay Strader, Christopher Usher, Vincenzo Pota
The Sluggs Survey: The Assembly Histories Of Individual Early-Type Galaxies, Duncan Forbes, Aaron Romanowsky, Nicola Pastorello, Caroline Foster, Jean Brodie, Jay Strader, Christopher Usher, Vincenzo Pota
Faculty Publications
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 of 24 early-type galaxies from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey with the hydrodynamical simulations of Naab et al. In particular, we use the kinematics of starlight up to 4 effective radii (Re) as diagnostics of galaxy inner and outer regions, and assign each galaxy to one of six Naab et al. assembly classes. The majority of our galaxies (14/24) have kinematic characteristics that indicate an assembly history dominated by gradual …
Hecs-Sz: The Hectospec Survey Of Sunyaev-Zeldovich-Selected Clusters, Kenneth J. Rines, Margaret J. Geller, Antonaldo Diaferio, Ho Seong Hwang
Hecs-Sz: The Hectospec Survey Of Sunyaev-Zeldovich-Selected Clusters, Kenneth J. Rines, Margaret J. Geller, Antonaldo Diaferio, Ho Seong Hwang
Physics & Astronomy
We estimate cluster masses and velocity dispersions for 123 clusters from optical spectroscopy to compare the Sunyaev–Zeldovich (SZ) mass proxy and dynamical masses. Our new survey, HeCS-SZ (Hectospec Cluster Survey of SZ-selected clusters), includes 7721 new or remeasured redshifts from MMT/Hectospec observations of 21 SZ-selected clusters at redshifts z = 0.05–0.20. We supplement the Hectospec data with spectra from the Sloan Digital Sky Survey (SDSS) and cluster data from the Cluster Infall Regions in SDSS project and the Hectospec Cluster Survey, our Hectospec survey of clusters selected by X-ray flux. We measure the scaling relation between velocity dispersion and SZ …
The Sluggs Survey: Chromodynamical Modelling Of The Lenticular Galaxy Ngc 1023, Arianna Cortesi, Ana Chies-Santos, Vincenzo Pota, Caroline Foster, Lodovico Coccato, Claudia Mendes De Oliveira, Duncan Forbes, Michael Merrifield, Steven Bamford, Aaron Romanowsky, Jean Brodie, Sreeja Kartha, Adebusola Alabi, Robert Proctor, Andres Almeida
The Sluggs Survey: Chromodynamical Modelling Of The Lenticular Galaxy Ngc 1023, Arianna Cortesi, Ana Chies-Santos, Vincenzo Pota, Caroline Foster, Lodovico Coccato, Claudia Mendes De Oliveira, Duncan Forbes, Michael Merrifield, Steven Bamford, Aaron Romanowsky, Jean Brodie, Sreeja Kartha, Adebusola Alabi, Robert Proctor, Andres Almeida
Faculty Publications
Globular clusters (GCs) can be considered discrete, long-lived, dynamical tracers that retain crucial information about the assembly history of their parent galaxy. In this paper, we present a new catalogue of GC velocities and colours for the lenticular galaxy NGC 1023, we study their kinematics and spatial distribution, in comparison with the underlying stellar kinematics and surface brightness profile, and we test a new method for studying GC properties. Specifically, we decompose the galaxy light into its spheroid (assumed to represent the bulge+halo components) and disc components and use it to assign to each GC a probability of belonging to …
The Sluggs Survey: Stellar Kinematics, Kinemetry And Trends At Large Radii In 25 Early-Type Galaxies, Caroline Foster, Nicola Pastorello, Joel Roediger, Jean Brodie, Duncan Forbes, Sreeja Kartha, Vincenzo Pota, Aaron Romanowsky, Lee Spitler, Jay Strader, Christopher Usher, Jacob Arnold
The Sluggs Survey: Stellar Kinematics, Kinemetry And Trends At Large Radii In 25 Early-Type Galaxies, Caroline Foster, Nicola Pastorello, Joel Roediger, Jean Brodie, Duncan Forbes, Sreeja Kartha, Vincenzo Pota, Aaron Romanowsky, Lee Spitler, Jay Strader, Christopher Usher, Jacob Arnold
Faculty Publications
Due to longer dynamical time-scales, the outskirts of early-type galaxies retain the footprint of their formation and assembly. Under the popular two-phase galaxy formation scenario, an initial in situ phase of star formation is followed by minor merging and accretion of ex situ stars leading to the expectation of observable transitions in the kinematics and stellar populations on large scales. However, observing the faint galactic outskirts is challenging, often leaving the transition unexplored. The large-scale, spatially resolved stellar kinematic data from the SAGES Legacy Unifying Galaxies and GlobularS (SLUGGS) survey are ideal for detecting kinematic transitions. We present kinematic maps …
Erratum: Global Properties Of ‘Ordinary’ Early-Type Galaxies: Photometry And Spectroscopy Of Stars And Globular Clusters In Ngc 4494, Caroline Foster, Lee Spitler, Aaron Romanowsky, Duncan Forbes, Vincenzo Pota, Kenji Bekki, Jay Strader, Robert Proctor, Jacob Arnold, Jean Brodie
Erratum: Global Properties Of ‘Ordinary’ Early-Type Galaxies: Photometry And Spectroscopy Of Stars And Globular Clusters In Ngc 4494, Caroline Foster, Lee Spitler, Aaron Romanowsky, Duncan Forbes, Vincenzo Pota, Kenji Bekki, Jay Strader, Robert Proctor, Jacob Arnold, Jean Brodie
Faculty Publications
This is an erratum to the paper entitled “Global properties of ‘ordinary’ early-type galaxies: photometry and spectroscopy of stars and globular clusters in NGC 4494”, published in MNRAS, 2011, 415, 3393.
New Spectroscopic Technique Based On Coaddition Of Surface Brightness Fluctuations: Ngc 4449 And Its Stellar Tidal Stream, Elisa Toloba, Puragra Guhathakurta, Aaron Romanowsky, Jean Brodie, David Martínez-Delgado, Jacob Arnold, Neel Ramachandran, Kuriakose Theakanath
New Spectroscopic Technique Based On Coaddition Of Surface Brightness Fluctuations: Ngc 4449 And Its Stellar Tidal Stream, Elisa Toloba, Puragra Guhathakurta, Aaron Romanowsky, Jean Brodie, David Martínez-Delgado, Jacob Arnold, Neel Ramachandran, Kuriakose Theakanath
Faculty Publications
No abstract provided.
The Sluggs Survey: A New Mask Design To Reconstruct The Stellar Populations And Kinematics Of Both Inner And Outer Galaxy Regions, Nicola Pastorello, Duncan Forbes, Adriano Poci, Aaron Romanowsky, Richard Mcdermid, Adebusola Alabi, Jean Brodie, Michele Cappellari, Vincenzo Pota, Caroline Foster
The Sluggs Survey: A New Mask Design To Reconstruct The Stellar Populations And Kinematics Of Both Inner And Outer Galaxy Regions, Nicola Pastorello, Duncan Forbes, Adriano Poci, Aaron Romanowsky, Richard Mcdermid, Adebusola Alabi, Jean Brodie, Michele Cappellari, Vincenzo Pota, Caroline Foster
Faculty Publications
Integral field unit spectrographs allow the 2D exploration of the kinematics and stellar populations of galaxies, although they are generally restricted to small fields-of-view. Using the large field-of-view of the DEIMOS multislit spectrograph on Keck and our Stellar Kinematics using Multiple Slits technique, we are able to extract sky-subtracted stellar light spectra to large galactocentric radii. Here, we present a new DEIMOS mask design named SuperSKiMS that explores large spatial scales without sacrificing high spatial sampling. We simulate a set of observations with such a mask design on the nearby galaxy NGC 1023, measuring stellar kinematics and metallicities out to …
Herschel Observations Of Edge-On Spirals (Heroes) : Ii. Tilted-Ring Modelling Of The Atomic Gas Disks., F. Allaert, G. Gentile, M. Baes, G. De Geyter, T. M. Hughes, F. Lewis, S. Bianchi, I. De Looze, J. Fritz, Benne W. Holwerda, J. Verstappen, S. Viaene
Herschel Observations Of Edge-On Spirals (Heroes) : Ii. Tilted-Ring Modelling Of The Atomic Gas Disks., F. Allaert, G. Gentile, M. Baes, G. De Geyter, T. M. Hughes, F. Lewis, S. Bianchi, I. De Looze, J. Fritz, Benne W. Holwerda, J. Verstappen, S. Viaene
Faculty Scholarship
Context. Edge-on galaxies can offer important insight into galaxy evolution because they are the only systems where the distribution of the different components can be studied both radially and vertically. The HEROES project was designed to investigate the interplay between the gas, dust, stars, and dark matter (DM) in a sample of 7 massive edge-on spiral galaxies. Aims. In this second HEROES paper, we present an analysis of the atomic gas content of 6 out of 7 galaxies in our sample. The remaining galaxy was recently analysed according to the same strategy. The primary aim of this work is to …
The Sluggs Survey: Globular Cluster Kinematics In A ‘Double Sigma’ Galaxy – Ngc 4473, Adebusola Alabi, Caroline Foster, Duncan Forbes, Aaron Romanowsky, Nicola Pastorello, Jean Brodie, Lee Spitler, Jay Strader, Christopher Usher
The Sluggs Survey: Globular Cluster Kinematics In A ‘Double Sigma’ Galaxy – Ngc 4473, Adebusola Alabi, Caroline Foster, Duncan Forbes, Aaron Romanowsky, Nicola Pastorello, Jean Brodie, Lee Spitler, Jay Strader, Christopher Usher
Faculty Publications
NGC 4473 is a so-called double sigma (2σ) galaxy, i.e. a galaxy with rare, double peaks in its 2D stellar velocity dispersion. Here, we present the globular cluster (GC) kinematics in NGC 4473 out to ∼10Re (effective radii) using data from combined Hubble Space Telescope/Advanced Camera for Surveys and Subaru/Suprime-Cam imaging and Keck/Deep Imaging Multi-Object Spectrograph. We find that the 2σ nature of NGC 4473 persists up to 3Re, though it becomes misaligned to the photometric major axis. We also observe a significant offset between the stellar and GC rotation amplitudes. This offset can be understood as a co-addition of …