External Galaxies Commons^™

The Loneliest Galaxies In The Universe: A Gama And Galaxy Zoo Study On Void Galaxy Morphology, Lori E. Porter, Benne Holwerda, Sandor Kruk, Maritza Lara-López, Kevin A. Pimbblet, Christopher P A Henry, Sarah Casura, Lee S. Kelvin

Faculty and Staff Scholarship

The large-scale structure of the Universe is comprised of galaxy filaments, tendrils, and voids. The majority of the Universe’s volume is taken up by these voids, which exist as underdense, but not empty, regions. The galaxies found inside these voids are expected to be some of the most isolated objects in the Universe. This study, using the Galaxy and Mass Assembly (GAMA) and Galaxy Zoo surveys, aims to investigate basic physical properties and morphology of void galaxies versus field (filament and tendril) galaxies. We use void galaxies with stellar masses (⁠M∗" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; …

Galaxy And Mass Assembly (Gama): Comparing Visually And Spectroscopically Identified Galaxy Merger Samples, Alice Desmons, Sarah Brough, Cristina Martínez-Lombilla, Roberto De Propris, Benne Holwerda, Ángel R. López-Sánchez

Faculty and Staff Scholarship

We conduct a comparison of the merging galaxy populations detected by a sample of visual identification of tidal features around galaxies as well as spectroscopically detected close pairs of galaxies to determine whether our method of selecting merging galaxies biases our understanding of galaxy interactions. Our volume-limited parent sample consists of 852 galaxies from the Galaxy And Mass Assembly (GAMA) survey in the redshift range 0.04 ≤ z ≤ 0.20 and stellar mass range 9.50 ≤ log 10(M⋆/M⊙)≤ 11.0" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; font-optical-sizing: inherit; font-kerning: inherit; …

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 and Staff 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 …

Modelling Strong Lenses From Wide-Field Ground-Based Observations In Kids And Gama, Shawn Knabel, Benne Holwerda, J Nightingale, T Treu, M Bilicki, S Brough, S Driver, L Finnerty, L Haberzettl, S Hegde, A M. Hopkins, K Kuijken, J Liske, A K. Pimblett, R C. Steele, A H. Wright

Faculty and Staff Scholarship

Despite the success of galaxy-scale strong gravitational lens studies with Hubble-quality imaging, a number of well-studied strong lenses remains small. As a result, robust comparisons of the lens models to theoretical predictions are difficult. This motivates our application of automated Bayesian lens modelling methods to observations from public data releases of overlapping large ground-based imaging and spectroscopic surveys: Kilo-Degree Survey (KiDS) and Galaxy and Mass Assembly (GAMA), respectively. We use the open-source lens modelling software PYAUTOLENS to perform our analysis. We demonstrate the feasibility of strong lens modelling with large-survey data at lower resolution as a complementary avenue to studies …

A Second Galaxy Missing Dark Matter In The Ngc 1052 Group, Pieter Van Dokkum, Shany Danieli, Roberto Abraham, Charlie Conroy, Aaron Romanowsky

Faculty Publications

The ultra-diffuse galaxy NGC1052-DF2 has a very low velocity dispersion, indicating that it has little or no dark matter. Here we report the discovery of a second galaxy in this class, residing in the same group. NGC1052-DF4closely resembles NGC1052-DF2 in terms of its size, surface brightness, and morphology; has a similar distance of Dsbf = 19.9 +/- 2.8 Mpc; and also has a population of luminous globular clusters extending out to >7 kpc from the center of the galaxy. Accurate radial velocities of the diffuse galaxy light and seven of the globular clusters were obtained with the Low Resolution Imaging …

Mirach’S Goblin: Discovery Of A Dwarf Spheroidal Galaxy Behind The Andromeda Galaxy, David Martínez-Delgado, Eva Grebel, Behnam Javanmardi, Walter Boschin, Nicolas Longeard, Julio Carballo-Bello, Dmitry Makarov, Michael Beasley, Giuseppe Donatiello, Martha Haynes, Duncan Forbes, Aaron Romanowsky

Faculty Publications

Context. It is of broad interest for galaxy formation theory to carry out a full inventory of the numbers and properties of dwarf galaxies, both satellite and isolated, in the Local Volume.Aims. Ultra-deep imaging in wide areas of the sky with small amateur telescopes can help to complete the census of these hitherto unknown low-surface-brightness galaxies, which cannot be detected by the current resolved stellar population and HI surveys. We report the discovery of Donatiello I, a dwarf spheroidal galaxy located one degree from the star Mirach (β And) in a deep image taken with an amateur telescope.Methods. The color-magnitude …

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 …

The Distance Of The Dark Matter Deficient Galaxy Ngc 1052–Df2, Pieter Van Dokkum, Shany Danieli, Yotam Cohen, Aaron Romanowsky, Charlie Conroy

Faculty Publications

We recently inferred that the galaxy NGC 1052–DF2 has little or no dark matter and a rich system of unusual globular clusters. We assumed that the galaxy is a satellite of the luminous elliptical galaxy NGC 1052 at ≈20 Mpc, on the basis of its surface brightness fluctuations (SBFs) distance of 19.0 ± 1.7 Mpc, its radial velocity of ≈1800 km s−1, and its projected position. Here we analyze the color–magnitude diagram (CMD) of NGC 1052–DF2, following the suggestion by Trujillo et al. that the tip of the red giant branch (TRGB) can be detected in currently available Hubble Space …

The Stellar Initial Mass Function In Early-Type Galaxies From Absorption Line Spectroscopy. Iii. Radial Gradients, Pieter Van Dokkum, Charlie Conroy, Alexa Villaume, Jean Brodie, Aaron Romanowsky

Faculty Research, Scholarly, and Creative Activity

No abstract provided.

Extensive Globular Cluster Systems Associated With Ultra Diffuse Galaxies In The Coma Cluster, Pieter Van Dokkum, Roberto Abraham, Aaron Romanowsky, Jean Brodie, Charlie Conroy, Shany Danieli, Deborah Lokhors, Allison Merritt, Lamiya Mowla, Jielai Zhang

Faculty Publications

We present Hubble Space Telescope (HST) imaging of two ultra diffuse galaxies (UDGs) with measured stellar velocity dispersions in the Coma cluster. The galaxies, Dragonfly 44 and DFX1, have effective radii of 4.7 kpc and 3.5 kpc and velocity dispersions of km s−1 and km s−1, respectively. Both galaxies are associated with a striking number of compact objects, tentatively identified as globular clusters: for Dragonfly 44 and for DFX1. The number of globular clusters is much higher than expected from the luminosities of the galaxies but is consistent with expectations from the empirical relation between dynamical mass and globular cluster …

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: 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 …

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.

Does The Stellar Disc Flattening Depend On The Galaxy Type, A. V. Mosenkov, N. Ya. Sotnikova, V. P. Reshetnikov, D. V. Bizyaev, Stefan Kautsch

Chemistry and Physics Faculty Articles

We analyse the dependence of the stellar disc flatness on the galaxy morphological type using 2D decomposition of galaxies from the reliable subsample of the Edge-on Galaxies in SDSS catalogue. Combining these data with the retrieved models of the edge-on galaxies from the Two Micron All Sky Survey and the Spitzer Survey of Stellar Structure in Galaxies catalogue, we make the following conclusions.

1. The disc relative thickness z₀/h in the near- and mid-infrared passbands correlates weakly with morphological type and does not correlate with the bulge-to-total luminosity ratio B/T in all studied bands.

2. Applying a 1D photometric …

Small Scatter And Nearly Isothermal Mass Profiles To Four Half-Light Radii From Two-Dimensional Stellar Dynamics Of Early-Type Galaxies, Michele Cappellari, Aaron Romanowsky, Jean Brodie, Duncan Forbes, Jay Strader, Caroline Foster, Sreeja Kartha, Nicola Pastorello, Vincenzo Pota, Lee Spitler, Christopher Usher, Jacob Arnold

Faculty Publications

No abstract provided.

Spectroscopic Confirmation Of The Existence Of Large, Diffuse Galaxies In The Coma Cluster, Pieter Van Dokkum, Aaron Romanowsky, Roberto Abraham, Jean Brodie, Charlie Conroy, Marla Geha, Allison Merritt, Alexa Villaume, Jielai Zhang

Faculty Publications

No abstract provided.

The Catalog Of Edge-On Disk Galaxies From Sdss. I. The Catalog And The Structural Parameters Of Stellar Disks, D. V. Bizyaev, Stefan Kautsch, A. V. Mosenkov, V. P. Reshetnikov, N. Ya. Sotnikova, N. V. Yablokova

Chemistry and Physics Faculty Articles

We present a catalog of true edge-on disk galaxies automatically selected from the Seventh Data Release of the Sloan Digital Sky Survey (SDSS). A visual inspection of the g, r, and iimages of about 15,000 galaxies allowed us to split the initial sample of edge-on galaxy candidates into 4768 (31.8% of the initial sample) genuine edge-on galaxies, 8350 (55.7%) non-edge-on galaxies, and 1865 (12.5%) edge-on galaxies not suitable for simple automatic analysis because these objects either show signs of interaction and warps, or nearby bright stars project on it. We added more candidate galaxies from RFGC, EFIGI, …

Forming Early-Type Galaxies In Groups Prior To Cluster Assembly, Stefan Kautsch, Anthony H. Gonzalez, Christian A. Soto, Kim-Vy H. Tran, Dennis Zaritsky, John Moustakas

Chemistry and Physics Faculty Articles

We study a unique protocluster of galaxies, the supergroup SG1120–1202. We quantify the degree to which morphological transformation of cluster galaxies occurs prior to cluster assembly in order to explain the observed early-type fractions in galaxy clusters at z = 0. SG1120–1202 at z ~ 0.37 is composed of four gravitationally bound groups that are expected to coalesce into a single cluster by z = 0. Using HST ACS observations, we compare the morphological fractions of the supergroup galaxies to those found in a range of environments. We find that the morphological fractions of early-type galaxies (~60%) and the ratio …