Physical Sciences and Mathematics Commons^™

Metallicity And Age Of The Stellar Stream Around The Disk Galaxy Ngc 5907, Seppo Laine, Carl Grillmair, Peter Capak, Richard Arendt, Aaron Romanowsky, David Martínez-Delgado, Matthew Ashby, James Davies, Stephen Majewski, Jean Brodie, R. Gabany, Jacob Arnold

Faculty Publications

Stellar streams have become central to studies of the interaction histories of nearby galaxies. To characterize the most prominent parts of the stellar stream around the well-known nearby (d = 17 Mpc) edge-on disk galaxy NGC 5907, we have obtained and analyzed new, deep gri Subaru/Suprime-Cam and 3.6 μm Spitzer/Infrared Array Camera observations. Combining the near-infrared 3.6 μm data with visible-light images allows us to use a long wavelength baseline to estimate the metallicity and age of the stellar population along an ~60 kpc long segment of the stream. We have fitted the stellar spectral energy distribution with a single-burst …

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 …

Galaxy And Mass Assembly : Accurate Panchromatic Photometry From Optical Priors Using Lambdar., A. H. Wright, A. S. G. Robotham, N. Bourne, S. P. Driver, L. Dunne, S. J. Maddox, M. Alpaslan, S. K. Andrews, A. E. Bauer, J. Bland-Hawthorn, Sarah Brough, M. J. I. Brown, C. Clarke, Michelle Cluver, L. J. M. Davies, M. W. Grootes, Benne W. Holwerda, A. M. Hopkins, T. H. Jarrett, Prajwal R. Kafle, Rebecca Lange, J. Liske, J. Loveday, A. J. Moffett, P. Norberg, C. C. Popescu, M. Smith, E. N. Taylor, R. J. Tuffs, L. Wang, S. M. Wilkins

Faculty Scholarship

We present the Lambda Adaptive Multi-Band Deblending Algorithm in R (LAMBDAR), a novel code for calculating matched aperture photometry across images that are neither pixel- nor PSF-matched, using prior aperture definitions derived from high-resolution optical imaging. The development of this program is motivated by the desire for consistent photometry and uncertainties across large ranges of photometric imaging, for use in calculating spectral energy distributions. We describe the program, specifically key features required for robust determination of panchromatic photometry: propagation of apertures to images with arbitrary resolution, local background estimation, aperture normalization, uncertainty determination and propagation, and object deblending. Using simulated …

Z  7 Galaxies With Red Spitzer/Irac [3.6]–[4.5] Colors In The Full Candels Data Set : The Brightest-Known Galaxies At Z ∼ 7–9 And A Probable Spectroscopic Confirmation At Z = 7.48., G. W. Roberts-Borsani, R. J. Bouwens, P. A. Oesch, I. Labbe, R. Smit, G. D. Illingworth, P. G. Van Dokkum, B. Holden, V. Gonzalez, M. Stefanon, Benne W. Holwerda, S. M. Wilkins

Faculty Scholarship

We identify four unusually bright (H160,AB < 25.5) galaxies from Hubble Space Telescope (HST) and Spitzer CANDELS data with probable redshifts z ∼ 7–9. These identifications include the brightest-known galaxies to date at z  7.5. As Y-band observations are not available over the full CANDELS program to perform a standard Lyman-break selection of z > 7 galaxies, we employ an alternate strategy using deep Spitzer/IRAC data. We identify z ∼ 7.1–9.1 galaxies by selecting z  6 galaxies from the HST CANDELS data that show quite red IRAC [3.6]−[4.5] colors, indicating strong [O III]+Hβ lines in the 4.5 μm band. This selection strategy was validated using a modest sample for which we have deep Y-band coverage, and subsequently used to select the brightest z 7 sources. Applying the IRAC criteria to all HST-selected optical dropout galaxies over the full ∼900 arcmin2 of the CANDELS survey revealed four unusually bright …

The Sluggs Survey: Globular Clusters And The Dark Matter Content Of Early-Type Galaxies, Duncan Forbes, Adebusola Alabi, Aaron Romanowsky, Jean Brodie, Jay Strader, Christopher Usher, Vincenzo Pota

Faculty Publications

No abstract provided.

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 …

The Ghosts Survey – Ii. The Diversity Of Halo Colour And Metallicity Profiles Of Massive Disc Galaxies., Antonela Monachesi, Eric F. Bell, David J. Radburn-Smith, Jeremy Bailin, Roelof S. De Jong, Benne W. Holwerda, David Streich, Grace Silverstein

Faculty Scholarship

We study the stellar halo colour properties of six nearby massive highly inclined disc galaxies using Hubble space telescope Advanced Camera for Surveys and Wide Field Camera 3 observations in both F606W and F814W filters from the GHOSTS (Galaxy Halos, Outer disks, Substructure, Thick disks, and Star clusters) survey. The observed fields probe the stellar outskirts out to projected distances of ∼50–70 kpc from their galactic centre along the minor axis. The 50 per cent completeness levels of the colour–magnitude diagrams are typically at 2 mag below the tip of the red giant branch (RGB). We …

Discovery Of An Ultra-Diffuse Galaxy In The Pisces-Perseus Supercluster, David Martínez-Delgado, Ronald Läsker, Margarita Sharina, Elisa Toloba, Jürgen Fliri, Rachael Beaton, David Valls-Gabaud, Igor Karachentsev, Taylor Chonis, Eva Grebel, Duncan Forbes, Aaron Romanowsky, J. Gallego-Laborda, Karel Teuwen, M. Gómez-Flechoso, Jie Wang, Puragra Guhathakurta, Serafim Kaisin, Nhung Ho

Faculty Publications

We report the discovery of DGSAT I, an ultra-diffuse, quenched galaxy located 10fdg4 in projection from the Andromeda galaxy (M31). This low-surface brightness galaxy (μV = 24.8 mag arcsec−2), found with a small amateur telescope, appears unresolved in sub-arcsecond archival Subaru/Suprime-Cam images, and hence has been missed by optical surveys relying on resolved star counts, in spite of its relatively large effective radius (Re(V) = 12'') and proximity (15') to the well-known dwarf spheroidal galaxy And II. Its red color (V − I = 1.0), shallow Sérsic index (nV = 0.68), and the absence of detectable Hα emission are typical …

Galaxy And Mass Assembly (Gama) : Panchromatic Data Release (Far-Uv–Far-Ir) And The Low-Z Energy Budget., Simon P. Driver, Angus H. Wright, Stephen K. Andrews, Luke J. M. Davies, Prajwal R. Kafle, Rebecca Lange, Amanda J. Moffett, Elizabeth Mannering, Aaron S. G. Robotham, Kevin Vinsen, Mehmet Alpaslan, Ellen Andrae, Ivan K. Baldry, Amanda E. Bauer, Steven P. Bamford, Joss Bland-Hawthorn, Nathan Bourne, Sarah Brough, Michael J. I. Brown, Michelle Cluver, Scott M. Croom, Matthew Colless, Christopher J. Conselice, Elisabete Da Cunha, Roberto De Propris, Michael Drinkwater, Loretta Dunne, Steve Eales, Alastair Edge, Carlos Frenk, Alister W. Graham, Meiert Grootes, Benne W. Holwerda, Andrew M. Hopkins, Edo Ibar, Eelco Van Kampen, Lee S. Kelvin, Tom Jarrett, D. Heath Jones, Maritza A. Lara-Lopez, Jochen Liske, Angel R. Lopez-Sanchez, Jon Loveday, Steve J. Maddox, Barry Madore, Smriti Mahajan, Martin Meyer, Peder Norberg, Samantha J. Penny, Steven Phillipps, Cristina C. Popescu, Richard Tuffs, John A. Peacock, Kevin A. Pimbblet, Matthew Prescott, Kate Rowlands, Anne E. Sansom, Mark Seibert, Matthew W. L. Smith, Will J. Sutherland, Edward N. Taylor, Elisabetta Valiante, J. Antonio Vazquez-Mata, Lingyu Wang, Stephen M. Wilkins, Richard P. Williams

Faculty Scholarship

We present the Galaxy And Mass Assembly (GAMA) Panchromatic Data Release (PDR) constituting over 230 deg2 of imaging with photometry in 21 bands extending from the far-UV to the far-IR. These data complement our spectroscopic campaign of over 300k galaxies, and are compiled from observations with a variety of facilities including: GALaxy Evolution eXplorer, Sloan Digital Sky Survey, Visible and Infrared Telescope for Astronomy (VISTA), Wide-field Infrared Survey Explorer, and Herschel, with the GAMA regions currently being surveyed by VLT Survey Telescope (VST) and scheduled for observations by Australian Square Kilometer Array Pathfinder (ASKAP). These data are processed to a …

Galaxy And Mass Assembly (Gama) : Growing Up In A Bad Neighbourhood – How Do Low-Mass Galaxies Become Passive?, L. J. M. Davies, A. S. G. Robotham, S. P. Driver, M. Alpaslan, I. K. Baldry, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, M. E. Cluver, Benne W. Holwerda, A. M. Hopkins, M. A. Lara-Lopez, S. Mahajan, A. J. Moffett, M. S. Owers, S. Phillipps

Faculty Scholarship

Both theoretical predictions and observations of the very nearby Universe suggest that low-mass galaxies(log10[M*/M⊙] < 9.5) are likely to remain star-forming unless they are affected by their local environment. To test this premise, we compare and contrast the local environment of both passive and star-forming galaxies as a function of stellar mass, using the Galaxy and Mass Assembly survey. We find that passive fractions are higher in both interacting pair and group galaxies than the field at all stellar masses, and that this effect is most apparent in the lowest mass galaxies. We also find that essentially all passive log10[M*/M⊙] < 8.5 galaxies are found in pair/group environments, suggesting that local interactions with a more massive neighbour cause them to cease forming new stars. We find that the effects of immediate environment (local galaxy–galaxy interactions) in forming passive systems increase with decreasing stellar mass, and highlight that this is potentially due to increasing interaction time-scales giving sufficient time for the galaxy to become passive via starvation. We then present a simplistic model to test this premise, and show that given our speculative assumptions, it is consistent with our observed results.

Globular Cluster Populations : Results Including S4g Late-Type Galaxies., Dennis Zaritsky, Kelsey Mccabe, Manuel Aravena, E. Athanassoula, Albert Bosma, Sebastien Comeron, Helene M. Courtois, Bruce G. Elmegreen, Debra M. Elmegreen, Santiago Erroz-Ferrer, Dimitri A. Gadotti, Joannah L. Hinz, Luis C. Ho, Benne W. Holwerda, Taehyun Kim, Johan H. Knapen, Jarkko Laine, Eija Laurikainen, Juan Carlos Muñoz-Mateos, Heikki Salo, Kartik Sheth

Faculty Scholarship

Using 3.6 and 4.5 μm images of 73 late-type, edge-on galaxies from the S4 G survey, we compare the richness of the globular cluster populations of these galaxies to those of early-type galaxies that we measured previously. In general, the galaxies presented here fill in the distribution for galaxies with lower stellar mass, M*, specifically log 10 ( ) M M *  < , overlap the results for early-type galaxies of similar masses, and, by doing so, strengthen the case for a dependence of the number of globular clusters per 109 Me of galaxy stellar mass, TN, on M*. For 8.5 log 10.5 ( ) M M * < <  we find the relationship can be satisfactorily described as T M N 106.7 0.56 ( ) * = - when M* is expressed in solar masses. The functional form of the relationship is only weakly constrained, and extrapolation outside this range is not advised. Our late-type galaxies, in contrast to our early types, do not show the tendency for low-mass galaxies to split into two TN families. Using these results and a galaxy stellar mass function from the literature, we calculate that, in a volume-limited, local universe sample, clusters are most likely to be found around fairly massive galaxies (M* ∼ 1010.8Me) and present a fitting function for the volume number density of clusters as a function of parent-galaxy stellar mass. We find no correlation between TN and large-scale environment, but we do find a tendency for galaxies of fixed M* to have larger TN if they have converted a larger proportion of their baryons into stars.

An Overmassive Dark Halo Around An Ultra-Diffuse Galaxy In The Virgo Cluster, Michael Beasley, Aaron Romanowsky, Vincenzo Pota, Ignacio Navarro, David Martinez-Delgado, Fabian Neyer, Aaron Deich

Faculty Publications

No abstract provided.

Stellar Populations Across The Black Hole Mass–Velocity Dispersion Relation, Ignacio Martín-Navarro, Jean Brodie, Remco Van Den Bosch, Aaron Romanowsky, Duncan Forbes

Faculty Publications

Coevolution between supermassive black holes (BH) and their host galaxies is universally adopted in models for galaxy formation. In the absence of feedback from active galactic nuclei (AGNs), simulated massive galaxies keep forming stars in the local universe. From an observational point of view, however, such coevolution remains unclear. We present a stellar population analysis of galaxies with direct BH mass measurements and the BH mass–σ relation as a working framework. We find that over-massive BH galaxies, i.e., galaxies lying above the best-fitting BH mass–σ line, tend to be older and more α-element-enhanced than under-massive BH galaxies. The scatter in …

A High Stellar Velocity Dispersion And ~100 Globular Clusters For The Ultra-Diffuse Galaxy Dragonfly 44, Pieter Van Dokkum, Roberto Abraham, Jean Brodie, Charlie Conroy, Shany Danieli, Allison Merritt, Lamiya Mowla, Aaron Romanowsky, Jielai Zhang

Faculty Publications

No abstract provided.

Bright Galaxies At Hubble's Redshift Detection Frontier : Preliminary Results And Design From The Redshift Z ~ 9-10 Borg Pure-Parallel Hst Survey., V. Calvi, M. Trenti, M. Stiavelli, P. A. Oesch, L. Bradley, K. B. Schmidt, D. Coe, G. Brammer, S. Bernard, R. J. Bouwens, D. Carrasco, C. M. Carollo, Benne W. Holwerda, J. W. Mackenty, C. A. Mason, J. M. Shull, T. Treu

Faculty Scholarship

We present the first results and design from the redshift z ∼ 9–10 Brightest of the Reionizing Galaxies Hubble Space Telescope survey BoRG[z9–10], aimed at searching for intrinsically luminous unlensed galaxies during the first 700 Myr after the Big Bang. BoRG[z9–10] is the continuation of a multi-year pure-parallel near-IR and optical imaging campaign with the Wide Field Camera 3. The ongoing survey uses five filters, optimized for detecting the most distant objects and offering continuous wavelength coverage from λ = 0.35 μm to λ = 1.7 μm. We analyze the initial ∼130 arcmin2 of area over 28 independent lines of …

Extragalactic Archeology With The Ghosts Survey : I. Age-Resolved Disk Structure Of Nearby Low-Mass Galaxies., David Streich, Roelof S. De Jong, Jeremy Bailin, Eric F. Bell, Benne W. Holwerda, Ivan Minchev, Antonela Monachesi, David J. Radburn-Smith

Faculty Scholarship

Aims. We study the individual evolution histories of three nearby low-mass edge-on galaxies (IC 5052, NGC 4244, and NGC 5023).

Methods. Using resolved stellar populations, we constructed star count density maps for populations of different ages and analyzed the change of structural parameters with stellar age within each galaxy.

Results. We do not detect a separate thick disk in any of the three galaxies, even though our observations cover a wider range in equivalent surface brightness than any integrated light study. While scale heights increase with age, each population can be well described by a single disk. Two of the …