Astrophysics and Astronomy Commons^™

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.

The Sluggs Survey: Kinematics For Over 2500 Globular Clusters In Twelve Early-Type Galaxies, V. Pota, D. A. Forbes, Aaron J. Romanowsky, J. P. Brodie, L. R. Spitler, J. Strader, C. Foster, J. A. Arnold, A. Benson, C. Blom, J. R. Hargis, K. L. Rhode, C. Usher

Faculty Publications

We present a spectrophotometric survey of 2522 extragalactic globular clusters (GCs) around 12 early-type galaxies, nine of which have not been published previously. Combining space-based and multicolour wide-field ground-based imaging, with spectra from the Keck/DEep Imaging Multi-Object Spectrograph (DEIMOS) instrument, we obtain an average of 160 GC radial velocities per galaxy, with a high-velocity precision of ∼15 km s−1 per GC. After studying the photometric properties of the GC systems, such as their spatial and colour distributions, we focus on the kinematics of metal-poor (blue) and metal-rich (red) GC subpopulations to an average distance of ∼8 effective radii from the …

Celestial Paleontology: The Legacy Of Dying Stars, Alexa Hodgson Hart

Electronic Theses and Dissertations

In their death throes, stars dole out their atmospheric material to the interstellar medium in dramatic stellar winds and spectacular explosions. The details of this profound metamorphosis, from star to remnant, play a key role in the next generation of star formation as well as the energetic and chemical evolution of galaxies and the universe as a whole. Dying stars are thought to be the source of all of the nuclei heavier than iron in the universe, as well as more complex molecules, such as carbon chains, which form the backbone of life as we know it.

High mass Wolf-Rayet …

Galaxy Inclination And Surface Brightness, Jordan C. Rozum, Shane L. Larson

Student Showcase

The distribution of spiral and bar galaxy inclination angles is expected to be uniform. However, analysis of several major galaxy catalogs shows this is not the case; galaxies oriented near edge-on are significantly more common in these catalogs. In an attempt to explain this discrepancy, we have developed a galaxy simulation code to compute the appearance of a spiral type galaxy as a function of its morphological parameters. We examine the dependence of observed brightness upon inclination angle by using smooth luminous mass density and interstellar medium (ISM) density distributions. The luminous mass component is integrated along a particular line …

Optimization Of Gold Nanoring Arrays For Biosensing In The Fiber-Optic Communication Window, Hao Jiang, Tingjie Li, Jun Yang, Silvia Mittler, Jayshri Sabarinathan

Physics and Astronomy Publications

To improve the limit of detection in a nanoplasmonic sensor system, the optical performance of the metal nanostructures should be optimized according to the best spectral window of the measurement instrument. We propose that the spectral window from 1460 to 1610 nm can potentially provide ultrahigh instrumental resolution for biosensing. We optimized gold nanoring arrays such that the extinction peak position is inside the proposed window, the extinction peak is sharp enough to track the peak shift with high resolution and the figure of merit (sensitivity/linewidth) of the array is optimized at the same time. The peak-sharpening effect of the …

A Biosensor Based On Periodic Arrays Of Gold Nanodisks Under Normal Transmission, Hao Jiang, Tingjie Li, Erden Ertorer, Jun Yang, Jayshri Sabarinathan, Silvia Mittler

Physics and Astronomy Publications

We present a biosensor based on periodic arrays of gold nanodisks patterned on top of a glass substrate. The sensor’s resonance wavelength, peak linewidth and figure of merit were studied both in experiments and in simulations. We analyzed the dependence of the sensor’s resolution on the inherent figure of merit of the sensor structure and the signal to noise ratio of the detection system. The best achieved refractive index resolution is 1.5×10-4 RIU and the detection limit on and antigen-antibody binding is better than 1 ng/mL.

Bright Radio Emission From An Ultraluminous Stellar-Mass Microquasar In M31, Matthew J. Middleton, James C. A. Miller-Jones, Sera Markoff, Rob Fender, Martin Henze, Natasha Hurley-Walker, Anna M. M. Scaife, Timorthy P. Roberts, Dominic Walton, John Carpenter, Jean-Pierre Macquart, Geoffrey C. Bower, Mark Gurwell, Wolfgang Pietsch, Frank Haberl, Jonathan Harris, Michael Daniel, Junayd Miah, Chris Done, John Morgan, Hugh Dickinson, Phil Charles, Vadim Burwitz, Massimo Della Valle, Michael Freyberg, Jochen Greiner, Margarita Hernanz, Dieter H. Hartmann, Despina Hatzidimitriou, Arno Riffeser, Gloria Sala, Stella Seitz, Pablo Reig, Arne Rau, Marina Orio, David Titterington, Keith Grainge

Publications

A subset of ultraluminous X-ray sources (those with luminosities < 10^40 erg s^-1)^1 are thought to be powered by the accretion of gas onto black holes with masses of ~5-20 M⊙, probably via an accretion disc. The X-ray and radio emission are coupled in such Galactic sources, with the radio emission originating in a relativistic jet thought to be launched from the innermost regions near the black hole4,5, with the most powerful emission occurring when the rate of infalling matter approaches a theoretical maximum (the Eddington limit). Only four such maximal sources are known in the Milky Way, and the absorption of soft X-rays in the interstellar medium precludes determining the causal sequence of events that leads to the ejection of the jet. Here we report radio and X-ray observations of a bright new X-ray source whose peak luminosity can exceed 1039 erg s^-1 in the nearby galaxy, M31. The radio luminosity is extremely high and shows variability on a timescale of tens of minutes, arguing that the source is highly compact and powered by accretion close to the Eddington limit onto a stellar mass black hole. Continued radio and X-ray monitoring of such sources should reveal the causal relationship between the accretion flow and the powerful jet emission.

Supersoft X-Rays Reveal A Classical Nova In The M31 Globular Cluster Bol 126, M. Henze, W. Pietsch, F. Haberl, M. Della Valle, A. Riffeser, G. Sala, D. Hatzidimitriou, F. Hofmann, Dieter H. Hartmann, J. Koppenhoefer

Publications

Context. Classical novae (CNe) represent the main class of supersoft X-ray sources (SSSs) in the central region of our neighbouring galaxy M 31. Only three confirmed novae and three SSSs have been discovered in globular clusters (GCs) of any galaxy so far, of which one nova and two SSSs (including the nova) were found in M 31 GCs. Aims. To study the SSS state of CNe we carried out a high-cadence X-ray monitoring of the M 31 central area with XMM-Newton and Chandra. This project is supplemented by regular optical monitoring programmes at various observatories. Methods. We analysed X-ray and …

Photometric Observations Of 782 Montefiore, 3842 Harlansmith, 5542 Moffatt, 6720 Gifu, And (19979) 1989 Vj, Xianming Han, Bin Li, Haibin Zhao, Wenjuan Liu, Luming Sun, Jingjing Shi, Shan Gao, Shufen Wang, Xiang Pan, Peng Jiang, Hongyan Zhou

Scholarship and Professional Work - LAS

Five solar system minor planets were measured photometrically between 2012 October and December using the SARA (Southeastern Association for Research in Astronomy) telescopes located in Kitt Peak National Observatory in USA and Cerro Tololo Inter-American Observatory in Chile. The following synodic periods were found: 782 Montefiore P = 4.0728 ± 0.0006 h; 3842 Harlansmith, P = 2.7938 ± 0.0005 h; 5542 Moffatt P = 5.187 ± 0.001 h; 6720 Gifu, P = 4.231 ± 0.001 h; and (19979) 1989 VJ, P = 7.568 ± 0.005 h.

Lightcurve Analysis Of Four Asteroids, Bin Li, Haibin Zhao, Xianming Han, Lina R. Annable, Eli M. Finkel, Orry R. Heffner, Adam W. Kidd, Bradley J. Magnetta, Tiffany M. Ramires, Frederick W. Rastede, Sean G. Sproston

Scholarship and Professional Work - LAS

From June 2011 through May 2012 May, photometric data for four asteroids were obtained using the Southeastern Association for Research in Astronomy (SARA) telescope located at the Kitt Peak National Observatory. The following synodic periods were found: 4808 Ballaero, P = 8.8976 ± 0.0007 h; 7750 McEwen, P = 27.82 ± 0.01 h; 11941 Archinal, P = 2.717 ±0.006 h; and (47035) 1998WS, P = 7.996 ± 0.001 h.

Rotation Periods Of 1660 Wood, 7173 Sepkoski, 12738 Satoshimiki, And (23233) 2000 Wm72, Xianming Han, Bin Li, Haibin Zhao

Scholarship and Professional Work - LAS

We present rotation periods of four asteroids: 1660 Wood, 7173 Sepkoski, 12738 Satoshimiki, and (23233) 2000 WM72. The observations were undertaken using the SARA (Southeastern Association for Research in Astronomy) South telescope, located in Cerro Tololo Inter-American Observatory in Chile, from 2011 December to 2012 April. The following synodic periods were found: 1660 Wood, P = 6.8088 ± 0.0002 h; 7173 Sepkoski, P = 2.44 ± 0.02 h; 12738 Satoshimiki, P = 8.708 ± 0.001 h; and (23233) 2000 WM72, P = 3.732 ± 0.003 h.

Photometric Observation Of 3024 Hainan, 3920 Aubignan, And 5951 Alicemonet, Bin Li, Haibin Zhao, Xianming Han, Wenjuan Liu, Luming Sun, Jingjing Shi, Shan Gao, Hongyan Zhou

Scholarship and Professional Work - LAS

Three minor planets were measured photometrically between 2012 September 4 and 21 using the SARA (Southeastern Association for Research in Astronomy) South telescope, located in Cerro Tololo Inter-American Observatory. The following synodic periods were found: 3024 Hainan, P = 11.785 ± 0.005 h; 3920 Aubignan, P = 4.4762 ± 0.0005 h; and 5951 Alicemonet, P = 3.8871 ± 0.0005 h.

Grb 091024a And The Nature Of Ultra-Long Gamma-Ray Bursts, F.J. Virgili, C.G. Mundell, V. Pal’Shin, C. Guidorzi, R. Margutti, A. Melandri, R. Harrison, S. Kobayashi, R. Chornock, A. Henden, Adria Updike, S.B. Cenko, N.R. Tanvir, I.A. Steele, A. Cucchiara, A. Gomboc, A. Levan, Z. Cano, C.J. Mottram, N.R. Clay, D. Bersier, D. KopaˇC, J. Japelj, A.V. Filippenko, W. Li, D. Svinkin, S. Golenetskii, D.H. Hartmann, P.A. Milne, G. Williams, P.T. O’Brien, D.B. Fox, E. Berger

Arts & Sciences Faculty Publications

We present a broadband study of gamma-ray burst (GRB) 091024A within the context of other ultra-long-duration GRBs. An unusually long burst detected by Konus–Wind (KW), Swift, and Fermi, GRB 091024A has prompt emission episodes covering ∼1300 s, accompanied by bright and highly structured optical emission captured by various rapid-response facilities, including the 2 m autonomous robotic Faulkes North and Liverpool Telescopes, KAIT, S-LOTIS, and the Sonoita Research Observatory.We also observed the burst with 8 and 10mclass telescopes and determine the redshift to be z = 1.0924 ± 0.0004. We find no correlation between the …

The Unusual Afterglow Of The Gamma-Ray Burst 100621a, J. Greiner, T. Krühler, M. Nardini, R. Filgas, A. Moin, C. De Breuck, F. Montenegro-Montes, A. Lundgren, S. Klose, P.M.J. Fonso, F. Bertoldi, J. Elliott, D.A. Kann, F. Knust, K. Menten, A. Nicuesa Guelbenzu, F. Olivares E., A. Rau, A. Rossi, P. Schady, S. Schmidl, G. Siringo, L. Spezzi, V. Sudilovsky, S.J. Tingay, Adria Updike, Z. Wang, A. Weiss, M. Wieringa, F. Wyrowski

Arts & Sciences Faculty Publications

Aims. With the afterglow of GRB 100621A being the brightest detected so far in X-rays, and superb GROND coverage in the optical/near-infrared during the first few hours, an observational verification of basic fireball predictions seemed possible. Methods. In order to constrain the broad-band spectral energy distribution of the afterglow of GRB 100621A, dedicated observations were performed in the optical/near-infrared with the 7-channel Gamma-Ray Burst Optical and Near-infrared Detector (GROND) at the 2.2mMPG/ESO telescope, in the sub-millimeter band with the large bolometer array LABOCA at APEX, and at radio frequencies with ATCA. Utilizing also Swift X-ray observations, we attempt an interpretation …

Semiclassical Partition Functions For Gravity With Cosmic Strings, Christopher L. Duston

Physics Faculty Publications

In this paper we describe an approach to construct semiclassical partition functions in gravity which are complete in the sense that they contain a complete description of the differentiable structures of the underlying 4-manifold. In addition, we find our construction naturally includes cosmic strings. We prove that the mass density of these strings uniquely specifies the topology of the leaves of a dimension 2 foliation, and conjecture that spacetime topology emerges as a result of the symmetry breaking of the fundamental fields. We discuss some possible applications of the partition functions in the fields of both quantum gravity and topological …