Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters – Iii. Analysis Of 30 Clusters,
2016
Bryant Space Center, Univeristy of Florida
Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters – Iii. Analysis Of 30 Clusters, R. Wagner-Kaiser, D. C. Stenning, A Sarajedini, Ted Von Hippel, D. A. Van Dyk, E. Robinson, W. H. Jefferys
Publications
We use Cycle 21 Hubble Space Telescope (HST) observations and HST archival ACS Treasury observations of 30 Galactic globular clusters to characterize two distinct stellar populations. A sophisticated Bayesian technique is employed to simultaneously sample the joint posterior distribution of age, distance, and extinction for each cluster, as well as unique helium values for two populations within each cluster and the relative proportion of those populations. We find the helium differences among the two populations in the clusters fall in the range of ∼0.04 to 0.11. Because adequate models varying in carbon, nitrogen, and oxygen are not presently available, we …
Metallicity And Age Of The Stellar Stream Around The Disk Galaxy Ngc 5907,
2016
California Institute of Technology
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 …
Book Review: How Do You Find An Exoplanet?,
2016
Embry-Riddle Aeronautical University
Book Review: How Do You Find An Exoplanet?, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of How Do You Find an Exoplanet? by John Asher Johnson. Princeton, 2016 178p bibl index afp, 9780691156811 $35.00, 9781400873999
The Mass Discrepancy Acceleration Relation In Early-Type Galaxies: Extended Mass Profiles And The Phantom Menace To Mond,
2016
Swinburne University of Technology
The Mass Discrepancy Acceleration Relation In Early-Type Galaxies: Extended Mass Profiles And The Phantom Menace To Mond, Joachim Janz, Michele Cappellari, Aaron Romanowsky, Luca Ciotti, Adebusola Alabi, Duncan Forbes
Faculty Publications
The dark matter (DM) haloes around spiral galaxies appear to conspire with their baryonic content: empirically, significant amounts of DM are inferred only below a universal characteristic acceleration scale. Moreover, the discrepancy between the baryonic and dynamical mass, which is usually interpreted as the presence of DM, follows a very tight mass discrepancy acceleration (MDA) relation. Its universality, and its tightness in spiral galaxies, poses a challenge for the DM interpretation and was used to argue in favour of MOdified Newtonian Dynamics (MOND). Here, we test whether or not this applies to early-type galaxies. We use the dynamical models of …
New Halo White Dwarf Candidates In The Sloan Digital Sky Survey,
2016
University of Oklahoma
New Halo White Dwarf Candidates In The Sloan Digital Sky Survey, Kyra Dame, A. Gianninas, Mukremin Kilic, Jeffrey A. Munn, Warren R. Brown, Kurtis A. Williams, Ted Von Hippel, Hugh C. Harris
Publications
We present optical spectroscopy and near-infrared photometry of 57 faint (g = 19–22) high proper motion white dwarfs identified through repeat imaging of ≈3100 deg2 of the Sloan Digital Sky Survey footprint by Munn et al. We use ugriz and JHphotometry to perform a model atmosphere analysis, and identify 10 ultracool white dwarfs with Teff < 4000 K, including the coolest pure H atmosphere white dwarf currently known, J1657+2638, with Teff = 3550 ± 100 K. The majority of the objects with cooling ages larger than 9 Gyr display thick disc kinematics and constrain the age of the thick disc to ≥11 Gyr. There are four white dwarfs in our sample with …
Obscured Agns In Bulgeless Hosts Discovered By Wise : The Case Study Of Sdss J1224+5555,
2016
George Mason University
Obscured Agns In Bulgeless Hosts Discovered By Wise : The Case Study Of Sdss J1224+5555, S. Satyapal, N. J. Secrest, B. Rothberg, J. A. O’Connor, S. L. Ellison, R. C. Hickox
Dartmouth Scholarship
There is mounting evidence that supermassive black holes form and grow in bulgeless galaxies. However, a robust determination of the fraction of AGNs in bulgeless galaxies, an important constraint to models of supermassive black hole seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been shown to be incomplete for low mass AGNs. In a recent study using the Wide-field Infrared Survey Explorer, we discovered hundreds of bulgeless galaxies that display mid-infrared signatures of extremely hot dust suggestive of powerful accreting massive black holes, despite having no signatures of black hole activity at optical wavelengths. …
The Sluggs Survey: The Mass Distribution In Early-Type Galaxies Within Five Effective Radii And Beyond,
2016
Swinburne University of Technology
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 Supermassive Black Hole And Double Nucleus Of The Core Elliptical Ngc 5419,
2016
Max Planck Institute for Extraterrestrial Physics
The Supermassive Black Hole And Double Nucleus Of The Core Elliptical Ngc 5419, Ximena Mazzalay, Jens Thomas, Roberto P. Saglia, Gary A. Wegner
Dartmouth Scholarship
We obtained adaptive-optics assisted SINFONI observations of the central regions of the giant elliptical galaxy NGC5419 with a spatial resolution of 0.2 arcsec (≈55 pc). NGC5419 has a large depleted stellar core with a radius of 1.58 arcsec (430 pc). HST and SINFONI images show a point source located at the galaxy's photocentre, which is likely associated with the low-luminosity AGN previously detected in NGC5419. Both the HST and SINFONI images also show a second nucleus, off-centred by 0.25 arcsec (≈70 pc). Outside of the central double nucleus, we measure an almost constant velocity dispersion of σ∼350 km/s. In the …
The Intrinsic Eddington Ratio Distribution Of Active Galactic Nuclei In Star-Forming Galaxies From The Sloan Digital Sky Survey,
2016
Dartmouth College
The Intrinsic Eddington Ratio Distribution Of Active Galactic Nuclei In Star-Forming Galaxies From The Sloan Digital Sky Survey, Mackenzie L. Jones, Ryan C. Hickox, Christine S. Black, Kevin N. Hainline, Michael A. Dipompeo, Andy D. Goulding
Dartmouth Scholarship
An important question in extragalactic astronomy concerns the distribution of black hole accretion rates of active galactic nuclei (AGNs). Based on observations at X-ray wavelengths, the observed Eddington ratio distribution appears as a power law, while optical studies have often yielded a lognormal distribution. There is increasing evidence that these observed discrepancies may be due to contamination by star formation and other selection effects. Using a sample of galaxies from the Sloan Digital Sky Survey Data Release 7, we test whether or not an intrinsic Eddington ratio distribution that takes the form of a Schechter function is consistent with previous …
Galaxies Probing Galaxies At High Resolution: Co-Rotating Gas Associated With A Milky Way Analog At Z = 0.4,
2016
University of Wisconsin - Madison
Galaxies Probing Galaxies At High Resolution: Co-Rotating Gas Associated With A Milky Way Analog At Z = 0.4, Aleksandar M. Diamond-Stanic, Alison L. Coil, John Moustakas, Christy A. Tremonti, Paul H. Sell, Alexander J. Mendez, Ryan C. Hickox, Greg H. Rudnick
Dartmouth Scholarship
We present results on gas flows in the halo of a Milky-Way-like galaxy at z = 0.413 based on high-resolution spectroscopy of a background galaxy. This is the first study of circumgalactic gas at high spectral resolution toward an extended background source (i.e., a galaxy rather than a quasar). Using long-slit spectroscopy of the foreground galaxy, we observe spatially extended Hα emission with a circular rotation velocity v circ ≈ 270 km s−1. Using echelle spectroscopy of the background galaxy, we detect and absorption lines at an impact parameter ρ= 27 kpc that are blueshifted from systemic …
A Tale Of Two Narrow-Line Regions: Ionization, Kinematics, And Spectral Energy Distributions For A Local Pair Of Merging Obscured Active Galaxies,
2016
University of Arizona
A Tale Of Two Narrow-Line Regions: Ionization, Kinematics, And Spectral Energy Distributions For A Local Pair Of Merging Obscured Active Galaxies, Kevin N. Hainline, Ryan C. Hickox, Chien-Ting Chen, Christopher M. Carroll, Mackenzie L. Jones, Alexandros S. Zervos, Andrew D. Goulding
Dartmouth Scholarship
We explore the gas ionization and kinematics, as well as the optical-IR spectral energy distributions for UGC 11185, a nearby pair of merging galaxies hosting obscured active galactic nuclei (AGNs), also known as SDSS J181611.72+423941.6 and J181609.37+423923.0 (J1816NE and J1816SW, z ≈ 0.04). Due to the wide separation between these interacting galaxies (~23 kpc), observations of these objects provide a rare glimpse of the concurrent growth of supermassive black holes at an early merger stage. We use BPT line diagnostics to show that the full extent of the narrow-line emission in both galaxies is photoionized by an AGN, and confirm …
Extending The Supermassive Black Hole Mass-Pitch Angle Relation To Moderate Redshifts,
2016
University of Arkansas, Fayetteville
Extending The Supermassive Black Hole Mass-Pitch Angle Relation To Moderate Redshifts, Logan H. Jones
Physics Undergraduate Honors Theses
I extend the empirical correlation between central supermassive black hole mass M and spiral arm pitch angle P in spiral galaxies to intermediate redshifts using a sample of 14 type 1 Seyfert galaxies. Nuclear black hole masses are measured from the widths and luminosities of the broad Hβ and MgII emission lines, and pitch angles are measured using two independent image analysis techniques. I find the best-fit relation log(M/M☉) = (8.31 ± 0.28) − (0.058 ± 0.016)P, which indicates little to no evolution compared to the published M-P relation for local spirals.
The Sluggs Survey*: Exploring The Globular Cluster Systems Of The Leo Ii Group And Their Global Relationships,
2016
Swinburne University of Technology
The Sluggs Survey*: Exploring The Globular Cluster Systems Of The Leo Ii Group And Their Global Relationships, Sreeja Kartha, Duncan Forbes, Adebusola Alabi, Jean Brodie, Aaron Romanowsky, Jay Strader, Lee Spitler, Zachary Jennings, Joel Roediger
Faculty Publications
We present an investigation of the globular cluster (GC) systems of NGC 3607 and NGC 3608 as part of the ongoing SLUGGS (SAGES Legacy Unifying Globulars and GalaxieS) survey. We use wide-field imaging data from the Subaru telescope in the g, r and i filters to analyse the radial density, colour and azimuthal distributions of both GC systems. With the complementary kinematic data obtained from the Keck II telescope, we measure the radial velocities of a total of 81 GCs. Our results show that the GC systems of NGC 3607 and NGC 3608 have a detectable spatial extent of ∼15 …
The Sluggs Survey: Globular Clusters And The Dark Matter Content Of Early-Type Galaxies,
2016
Swinburne University of Technology
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.
Tev Gamma-Ray Observations Of The Galactic Center Ridge By Veritas,
2016
Department of Physical Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland
Tev Gamma-Ray Observations Of The Galactic Center Ridge By Veritas, P. T. Reynolds, Et Al
Physical Sciences Publications
The Galactic Center ridge has been observed extensively in the past by both GeV and TeV gamma-ray instruments revealing a wealth of structure, including a diffuse component and the point sources G0.9+0.1 (a composite supernova remnant) and Sgr A* (believed to be associated with the supermassive black hole located at the center of our Galaxy). Previous very high energy (VHE) gamma-ray observations with the H.E.S.S. experiment have also detected an extended TeV gamma-ray component along the Galactic plane in the >300 GeV gamma-ray regime. Here we report on observations of the Galactic Center ridge from 2010 to 2014 by the …
Erratum: The Sluggs Survey: The Globular Cluster Systems Of Three Early-Type Galaxies Using Wide-Field Imaging,
2016
Swinburne University of Technology
Erratum: The Sluggs Survey: The Globular Cluster Systems Of Three Early-Type Galaxies Using Wide-Field Imaging, Sreeja Kartha, Duncan Forbes, Lee Spitler, Aaron Romanowsky, Jacob Arnold, Jean Brodie
Faculty Publications
The paper ‘The SLUGGS survey: the globular cluster systems of three early-type galaxies using wide-field imaging’ was published in Monthly Notices of the Royal Astronomical Society, 437, 273 – 292 (2014).
The Sluggs Survey: The Assembly Histories Of Individual Early-Type Galaxies,
2016
Swinburne University of Technology
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 …
Discovery Of An Ultra-Diffuse Galaxy In The Pisces-Perseus Supercluster,
2016
Universität Heidelberg
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 …
Peering Through The Dust: Nustar Observations Of Two First-2mass Red Quasars,
2016
Yale University
Peering Through The Dust: Nustar Observations Of Two First-2mass Red Quasars, Stephanie M. Lamassa, Angelo Ricarte, Eilat Glikman, C. Megan Urry, Daniel Stern, Tahir Yaqoob, George B. Lansbury, Francesca Civano
Dartmouth Scholarship
Some reddened quasars appear to be transitional objects in the merger-induced black hole growth/galaxy evolution paradigm, where a heavily obscured nucleus starts to be unveiled by powerful quasar winds evacuating the surrounding cocoon of dust and gas. Hard X-ray observations are able to peer through this gas and dust, revealing the properties of circumnuclear obscuration. Here, we present NuSTAR and XMM-Newton/Chandra observations of FIRST-2MASS selected red quasars F2M 0830+3759 and F2M 1227+3214. We find that though F2M 0830+3759 is moderately obscured (NH,Z=2.1±0.2×1022 cm−2) and F2M 1227+3214 is mildly absorbed (NH,Z=3.4+0.8−0.7×1021 cm−2 …
The Sluggs Survey: Stellar Kinematics, Kinemetry And Trends At Large Radii In 25 Early-Type Galaxies,
2016
Australian Astronomical Observatory
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 …
