Astrophysics and Astronomy Commons^™

The X-Ray Evolution Of Hickson Compact Groups, Christopher Fuse, Emma Broming

Student-Faculty Collaborative Research Publications

The Hickson compact groups, displaying regions of high galaxy densities, should provide environments where galaxy evolution occurs rapidly. The repeated galaxy interactions and mergers present in compact groups increase the rate of star formation and increase the number of X-ray binaries. A fraction of the Hi gas will also become heated via stirring and shocks, which yields extended diffuse, hot gas halos that can encompass all members of a compact group. Using a sample of 16 Hickson compact groups from the Chandra X-Ray Observatory archives, we report on a correlation between the diffuse X-ray gas and the total X-ray point …

Sfa Star Charts, W D. Bruton

Faculty Publications

The SFA Start Charts are designed to work anywhere on Earth. Instructions are included on the last two pages. The constellations lines are based in part on those in a book called The Stars by H. A. Rey. These constellation patterns were adopted by Google Sky.

Evidence Of Light-Bending Effects And Its Implication For Spectral State Transitions, R. C. Reis, J. M. Miller, M. T. Reynolds, A. C. Fabian, D. J. Walton, E. Cackett, J. F. Steiner

Physics and Astronomy Faculty Research Publications

It has long been speculated that the nature of the hard X-ray corona may be an important second driver of black hole state transitions, in addition to the mass accretion rate through the disk. However, a clear physical picture of coronal changes has not yet emerged. We present results from a systematic analysis of Rossi X-Ray Timing Explorer observations of the stellar-mass black hole binary XTE J1650-500. All spectra with significant hard X-ray detections were fit using a self-consistent, relativistically blurred disk reflection model suited to high ionization regimes. Importantly, we find evidence that both the spectral and timing properties …

Regulation Of Black Hole Winds And Jets Across The Mass Scale, A. L. King, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, K. Gültekin, E. M. Cackett, S. W. Allen, D. Proga, T. R. Kallman

Physics and Astronomy Faculty Research Publications

We present a study of the mechanical power generated by both winds and jets across the black hole mass scale. We begin with the study of ionized X-ray winds and present a uniform analysis using Chandra grating spectra. The high-quality grating spectra facilitate the characterization of the outflow velocity, ionization, and column density of the absorbing gas. We find that the kinetic power of the winds, derived from these observed quantities, scales with increasing bolometric luminosity as log (L _{wind, 42}/C_v ) = (1.58 ± 0.07)log (L _{Bol, 42}) - (3.19 ± 0.19). This suggests that supermassive …

The Planetary Nebula Spectrograph Survey Of S0 Galaxy Kinematics. Data And Overview, A. Cortesi, M. Arnaboldi, L. Coccato, M. R. Merrifield, O. Gerhard, S. Bamford, Aaron J. Romanowsky, N. R. Napolitano, N. G. Douglas, K. Kuiijken, M. Capaccioli, K. C. Freeman, A. L. Chies-Santos, V. Pota

Faculty Publications

The origins of S0 galaxies remain obscure, with various mechanisms proposed for their formation, likely depending on environment. These mechanisms would imprint different signatures in the galaxies' stellar kinematics out to large radii, offering a method for distinguishing between them. We aim to study a sample of six S0 galaxies from a range of environments, and use planetary nebulae (PNe) as tracers of their stellar populations out to very large radii, to determine their kinematics in order to understand their origins. Using a special-purpose instrument, the Planetary Nebula Spectrograph, we observe and extract PNe catalogues for these six systems*. We …

The Sluggs Survey: Wide Field Imaging Of The Globular Cluster System Of Ngc 4278, C. Usher, D. A. Forbes, L. R. Spitler, J. P. Brodie, Aaron J. Romanowsky, J. Strader, K. A. Woodley

Faculty Publications

We use multipointing Hubble Space Telescope Advanced Camera for Surveys and wide field Subaru Suprime-Cam imaging to study the globular cluster system of the L* elliptical galaxy NGC 4278. We have also obtained a handful of new globular cluster spectra with the Keck Deep Imaging Multi-Object Spectrograph. We determine the globular cluster surface density profile and use it to calculate the total number of globular clusters, finding the system to be slightly more populous than average for galaxies of its luminosity. We find clear evidence for bimodality in the globular cluster colour distribution and for a colour–magnitude relation in the …

Mond And Imf Variations In Early-Type Galaxies From Atlas3d, C. Tortora, Aaron J. Romanowsky, V. F. Cardone, N. R. Napolitano, Ph Jetzer

Faculty Publications

No abstract provided.

The Sluggs Survey: Outer Triaxiality In The Fast Rotator Elliptical Ngc 4473, C. Foster, J. A. Arnold, D. A. Forbes, N. Pastorello, Aaron J. Romanowsky, L. R. Spitler, J. Strader, J. P. Brodie

Faculty Publications

Systematic surveys of nearby early-type galaxies using integral field unit (IFU) spectrograph data have revealed that galaxies can hide interesting structures only visible through kinematic studies. As part of their pioneering work, the ATLAS3D team have shown that most morphologically elliptical galaxies are centrally kinematically disc like. Hence, while global morphology suggests that ellipticals are ellipsoidal/triaxial in shape, their central kinematics may be consistent with (inclined) oblate systems. Here, we study the fast rotator elliptical galaxy: NGC 4473. Using slitlets, we obtain galaxy light kinematics out to unprecedentedly large galactocentric radii (2.5 effective radii). While we confirm the IFU results …

Filling The Gap: A New Class Of Old Star Cluster?, D. A. Forbes, V. Pota, C. Usher, Aaron J. Romanowsky, J. Strader, J. P. Brodie, J. A. Arnold, L. R. Spitler

Faculty Publications

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 types with different origins. Utilizing the Hubble Space Telescope to measure sizes and long exposures on the Keck 10 m telescope to obtain distances, we have discovered the first confirmed star clusters that lie within a previously claimed size–luminosity gap dubbed the ‘avoidance zone’ by Hwang et al. The existence of these star clusters extends the range of sizes, masses and densities for star clusters, and argues against current formation models that …

The Sluggs Survey: The Globular Cluster Systems Of Three Early-Type Galaxies Using Wide-Field Imaging, S. S. Kartha, D. A. Forbes, L. R. Spitler, Aaron J. Romanowsky, J. A. Arnold, J. P. Brodie

Faculty Publications

We present the results from a wide-field imaging study of globular cluster (GC) systems in three early-type galaxies. Combinations of Subaru/Suprime-Cam, CFHT/MegaCam and HST/WFPC2/ACS data were used to determine the GC system properties of three highly flattened galaxies NGC 720, NGC 1023 and NGC 2768. This work is the first investigation of the GC system in NGC 720 and NGC 2768 to very large galactocentric radius (∼ 100 kpc). The three galaxies have clear blue and red GC subpopulations. The radial surface densities of the GC systems are fitted with Sersic profiles, and detected out to 15, 8 and 10 …

Abundance Patterns In The Spiral Galaxy Messier 33, Melissa A. Siemer, Ravi Sankrit

STAR Program Research Presentations

Messier 33 (M33) is a spiral disk galaxy, similar to our galaxy, approximately 3 million light-years from Earth. Because of its proximity to Earth and face-on viewing angle, it is easy to see individual objects. Consequently, M33 is in an ideal position for obtaining data on elemental abundances. By studying M33, we learn how galaxies like our own form and change over time.

We use published optical spectroscopic data, obtained and assembled from online sources, to map the abundances of various elements (Helium, Nitrogen, Oxygen, Neon, Argon, Sulfur) in the planetary nebula and HII region populations of M33. We classify …

Seeing Through A Cloudy Glass: Putting Limits On Planetary Nebulae Abundances Using Photoionization Modeling., Peter R. Sullivan, Ravi Sankrit

STAR Program Research Presentations

Planetary nebulae (PNe) form around low to intermediate mass stars transitioning from the giant branch to white dwarf phase. The outer layer of the star is ejected during the transition and this gas, ionized by the central star, emits a line-spectrum. This spectrum traces the chemical abundances that were characteristic of the interstellar medium in which the star formed (e.g. oxygen) as well as of the elements created by these progenitor stars (e.g. nitrogen) aiding our understanding of chemical evolution of galaxies. In this project, we use modeling of the emission lines of PNe to determine the accuracy of direct …

Chemical Compatibility Study Of Anti-Corrosive Materials For Stratospheric Observatory For Infrared Astronomy (Sofia), Belyn Nicole Grant, Zaheer Ali, Greg Perryman, Stefan Teufel, Brian Eney

STAR Program Research Presentations

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a telescope designed to capture infrared light from deep space, mounted in a highly modified Boeing 747 SP. Portions of the aircraft interior are showing signs of corrosion, and need to be coated with a material that will prevent further corrosion. Up to date, current anti-corrosive materials commonly used on aircrafts are incompatible with the very thin aluminum surface of the telescope mirrors. The purpose of our study is to find an effective corrosion preventive material with low outgassing properties.

Precision Measurement Of The Most Distant Spectroscopically Confirmed Supernova Ia With The Hubble Space Telescope, D Rubin, R A. Knop, E Rykoff, G Aldering, R Amanullah, K Barbary, M S. Burns, A Conley, N Connolly, S Deustua, V Fadeyev, H K. Fakhouri, A S. Fruchter, R A. Gibbons, G Goldhaber, A Goobar, E Y. Hsiao, Xiaosheng Huang, M Kowalski, C Lidman, J Meyers, J Nordin, S Perlmutter, C Saunders, A Spadafora, V Stanishev, N Suzuki, L Wang, Supernova Cosmology Project

Physics and Astronomy

We report the discovery of a redshift 1.71 supernova in the GOODS North field. The Hubble Space Telescope (HST) ACS spectrum has almost negligible contamination from the host or neighboring galaxies. Although the rest frame sampled range is too blue to include any Si ii line, a principal component analysis allows us to confirm it as a Type Ia supernova with 92% confidence. A recent serendipitous archival HST WFC3 grism spectrum contributed a key element of the confirmation by giving a host-galaxy redshift of 1.713 +/- 0.007. In addition to being the most distant SN Ia with spectroscopic confirmation, this …

Discovery Of A Magnetic Field In The Rapidly Rotating O-Type Secondary Of The Colliding-Wind Binary Hd 47129 (Plaskett's Star), J. H. Grunhut, G. A. Wade, M. A. Leutenegger, V. Petit, G. Rauw, C. Neiner, F. Martins, David H. Cohen, M. Gagné, R. Ignace, S. Mathis, S. E. De Mink, A. F.J. Moffat, S. P. Owocki, M. Shultz, J. O. Sundqvist

Physics & Astronomy Faculty Works

We report the detection of a strong, organized magnetic field in the secondary component of the massive O8III/I+O7.5V/III double-lined spectroscopic binary system HD 47129 (Plaskett's star) in the context of the Magnetism in Massive Stars survey. Eight independent Stokes V observations were acquired using the Echelle SpectroPolarimetric Device for the Observations of Stars (ESPaDOnS) spectropolarimeter at the Canada-France-Hawaii Telescope and the Narval spectropolarimeter at the Telescope Bernard Lyot. Using least-squares deconvolution we obtain definite detections of signal in Stokes V in three observations. No significant signal is detected in the diagnostic null (N) spectra. The Zeeman signatures are broad and …

The Escape Fraction Of Ionizing Radiation From Galaxies, A Benson, Aparna Venkatesan, J Shull

Physics and Astronomy

The escape of ionizing radiation from galaxies plays a critical role in the evolution of gas in galaxies, and the heating and ionization history of the intergalactic medium. We present semi-analytic calculations of the escape fraction of ionizing radiation for both hydrogen and helium from galaxies ranging from primordial systems to disk-type galaxies that are not heavily dust-obscured. We consider variations in the galaxy density profile, source type, location, and spectrum, and gas overdensity/distribution factors. For sufficiently hard first-light sources, the helium ionization fronts closely track or advance beyond that of hydrogen. Key new results in this work include calculations …

The Sluggs Survey: Probing The Supermassive Blackhole Connection With Bulges And Haloes Using Red And Blue Globular Cluster Systems, V. Pota, A. W. Graham, D. A. Forbes, Aaron J. Romanowsky, A. J. Brodie, J. Strader

Faculty Publications

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 hole formation itself. In this paper, we approach this issue by investigating extragalactic globular cluster (GC) systems, which can be used to probe the physics of both the bulge and the halo of the host galaxy. We study the relation between the supermassive black hole masses (MBH) and the GC system velocity dispersions (σGC) using an updated and improved sample of 21 galaxies. We exploit the dichotomy of GC system colours, to test …

An Inventory Of The Stellar Initial Mass Function In Early-Type Galaxies, C. Tortora, Aaron J. Romanowsky, N. R. Napolitano

Faculty Publications

Given a flurry of recent claims for systematic variations in the stellar initial mass function (IMF), we carry out the first inventory of the observational evidence using different approaches. This includes literature results, as well as our own new findings from combined stellar population synthesis (SPS) and Jeans dynamical analyses of data on ~4500 early-type galaxies (ETGs) from the SPIDER project. We focus on the mass-to-light ratio mismatch relative to the Milky Way IMF, δIMF, correlated against the central stellar velocity dispersion, σsstarf. We find a strong correlation between δIMF and σsstarf, for a wide set of dark matter (DM) …

The Sluggs Survey: Wide-Field Stellar Kinematics Of Early-Type Galaxies, J. A. Arnold, Aaron J. Romanowsky, J. P. Brodie, D. A. Forbes, J. Strader, C. Foster, S. S. Kartha, N. Pastorello, V. Pota, C. Usher, K. A. Woodley

Faculty Publications

No abstract provided.

Mather Explains The Known And Unknown Universe, Aldemaro Romero Jr.

Publications and Research

No abstract provided.