Bulletin of the American Physical Society
2014 Annual Meeting of the Mid-Atlantic Section of the APS
Volume 59, Number 9
Friday–Sunday, October 3–5, 2014; University Park, Pennsylvania
Session H4: Time Domain Astrophysics, Observational Cosmology and Exoplanets |
Hide Abstracts |
Chair: David Burrows, Pennsylvania State University Room: Life Sciences Building 007 |
Sunday, October 5, 2014 9:00AM - 9:36AM |
H4.00001: Unveiling the Progenitors of Short Duration Gamma-Ray Bursts Invited Speaker: Brad Cenko While the connection between long duration gamma-ray bursts (GRBs) and massive star core-collapse has been firmly established over the last two decades, the progenitor system of short duration GRBs has proven more difficult to pin down observationally. With the discovery of the first long-wavelength afterglows of short GRBs following the launch of the Swift satellite, we have slowly accumulated evidence supporting a binary neutron star merger origin for these systems. In this talk I will summarize the indirect evidence supporting a link between neutron star mergers and short duration GRBs, as well as ongoing attempts to uncover a direct ``smoking gun'' signature, either in the form of neutron-rich (r-process) material tidally ejected during the merger (``kilonova'' emission) and/or the coincident detection of gravitational waves from the Advanced Ligo/Virgo network. [Preview Abstract] |
Sunday, October 5, 2014 9:36AM - 9:48AM |
H4.00002: Bridging the gap between theory and observations of galaxies across cosmic time Yuexing Li, Lars Hernquist, Mark Vogelsberger, Volker Springel A major recent milestone in observational cosmology is the detection of a large number of galaxies and quasars across cosmic time through multi-wavelength surveys. In order to interpret the wealth of data and to understand the origin and destination of these objects, a comprehensive model which fully accounts for the formation, evolution and multi-band properties of structures is imperative. However, despite the strong observational push, theoretical modeling in this field has lagged behind. Here, I report the Illustris radiative transfer project, which performs comprehensive radiative transfer calculations on the Illustris Simulation, the largest and most sophisticated cosmological simulation to date, to investigate the multi-band properties of galaxies and quasars from the cosmic dawn to the present day. I will present new results on the cosmic reionization, the origins of extragalactic background lights, and detectability of the first galaxies with the next generation instruments such as JWST and ALMA. [Preview Abstract] |
Sunday, October 5, 2014 9:48AM - 10:00AM |
H4.00003: Evolution in the Black Hole - Galaxy Scaling Relations and the Duty Cycle of Nuclear Activity in Star-Forming Galaxies Mouyuan Sun, J.R. Trump, W.N. Brandt, D. Alexander, K. Jahnke, D.J. Rosario, S.X. Wang, Y.Q. Xu, B. Luo We measure the location and evolutionary vectors of 70 Herschel -detected broad-line active galactic nuclei (BLAGNs) in the MBH $-$ M$\ast $ plane. BLAGNs are selected from the COSMOS and CDF-S fields, and span the redshift range 0.2 $\le $ z \textless 2.1. We find our sample is consistent with no evolution in the MBH $-$ M$\ast $ relation from z $\sim $ 2 to z $\sim $ 0. BLAGNs and their host-galaxies which lie off the black hole mass--galaxy total stellar mass relation tend to have evolutionary vectors pointing back to the relation. We also use the measured growth rates to estimate the preferred AGN duty cycle for our galaxies to evolve most consistently onto the local MBH $-$ MBul relation. Under reasonable assumptions of exponentially declining star formation histories, the data suggest a non-evolving (or weak-evolving) BLAGN duty cycle among star-forming galaxies of $\sim $ 6{\%} (1 sigma range of 0.05 $-$ 30{\%} at z \textless 1 and 0.6 $-$ 25{\%} at z \textgreater 1). [Preview Abstract] |
Sunday, October 5, 2014 10:00AM - 10:12AM |
H4.00004: Photometric Redshifts in the Hawaii-Hubble Deep Field-North (H-HDF-N) Guang Yang, Y.Q. Xue, B. Luo, W.N. Brandt We derive photometric redshifts (zphot) for sources in the entire ($\sim $ 0.4 deg2) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point spread function-matched photometry of 15 broad bands from the ultraviolet (U band) to mid-infrared (IRAC 4.5 $\mu $m). Our catalog consists of a total of 131,678 sources. We evaluate the zphot quality by comparing zphot with spectroscopic redshifts (zspec) when available, and find a value of normalized median absolute de- viation $\sigma $NMAD$=$ 0.029 and an outlier fraction of 5.5{\%} (outliers are defined as sources having \textbar zphot $-$ zspec\textbar /(1 $+$ zspec) \textgreater 0.15) for non-X-ray sources. Our zphot quality is comparable to those presented in similar works that derive zphot utilizing broadband photometry. We also classify each object as star or galaxy through template spectral energy distribu- tion fitting, resulting in 4913 stars and 126,765 galaxies. Furthermore, we match our catalog with the 2 Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having zspec), we improve their zphot quality by adding three additional AGN templates, achieving $\sigma $NMAD$=$ 0.037 and an outlier fraction of 12.8{\%}. We make our catalog publicly available presenting both photometry and zphot, and provide guidance on how to make use of our catalog. [Preview Abstract] |
Sunday, October 5, 2014 10:12AM - 10:24AM |
H4.00005: Weak Hard X-ray Emission from Broad Absorption Line Quasars Observed with NuSTAR: Evidence for Intrinsic X-ray Weakness Bin Luo, Niel Brandt We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z$=$0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z\textless 1.3. However, their rest-frame 2 keV luminosities are 14 to \textgreater 330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with \textless 45 counts in the 3-24 keV band, and the other three are not detected. The hard X-ray (8-24 keV) weakness observed by NuSTAR requires Compton-thick absorption if these objects have nominal underlying X-ray emission. However, a soft stacked effective photon index ($\Gamma \sim 1.8$) for this sample disfavors Compton-thick absorption in general. The uniform hard X-ray weakness observed by NuSTAR for this and the pilot samples selected with \textless 10 keV weakness also suggests that the X-ray weakness is intrinsic in at least some of the targets. We conclude that the NuSTAR observations have likely discovered a significant population (\textgreater 33{\%}) of intrinsically X-ray weak objects among the BAL quasars with significantly weak \textless 10 keV emission. [Preview Abstract] |
Sunday, October 5, 2014 10:24AM - 10:36AM |
H4.00006: New Probes of Quasar Winds: Multi-Year Variability and Redshifted Troughs William Brandt, Nurten Filiz Ak, Patrick Hall, Donald Schneider Winds are key parts of quasar nuclear environments, likely assisting mass accretion and providing feedback into typical massive galaxies. They are most directly observed via prominent absorption in the UV (e.g., Broad Absorption Lines: BALs) and X-ray bands. I will highlight results coming from two new probes of quasar winds: (1) multi-year variability surveys that can now systematically investigate large samples (hundreds-to-thousands of objects), and (2) rare redshifted BAL troughs, which may arise from high-velocity inflows, rotationally dominated outflows, or binary quasars. I will end by describing some key unresolved questions and future prospects. [Preview Abstract] |
Sunday, October 5, 2014 10:36AM - 10:48AM |
H4.00007: Atmosphere of a Transiting Hot-Jupiter System, Probed in the Lyman-alpha Band Louis Oberto, Zheng Zheng A Jupiter-like extrasolar planet (i.e., a hot-Jupiter), close to the host star, can have an atmosphere extending to several times the planet radius, as a result of heating from the star. Such an extended atmosphere is transparent to visible light and hard to be observed in the optical band. However, in the Lyman-$\alpha$ band, the extended atmosphere can be detected, because of the interaction of Lyman-$\alpha$ photons with the neutral hydrogen atoms in the atmosphere. A fraction of the Lyman-$\alpha$ photons emitted from the star are intercepted by the planet, and these photons experience resonant scattering in the planet's atmosphere and eventually escape the atmosphere. Therefore, in the Lyman-$\alpha$ band, the planet appears to be effectively emitting light. We perform a Lyman-$\alpha$ radiative transfer study of a model transiting hot-Jupiter system. In the Lyman-$\alpha$ band, the transit signal is much stronger (compared to that in the optical band), due to the extended atmosphere. The effective Lyman-$\alpha$ emission from the planet also shows a phase variation as the planet orbits around the star. We investigate how the transit and phase-change light curve depends on the distribution of neutral hydrogen in the atmosphere, as well as the velocity of the atmosphere. [Preview Abstract] |
Sunday, October 5, 2014 10:48AM - 11:00AM |
H4.00008: Status of the LISA Pathfinder Mission Jacob Slutsky LISA Pathfinder is a technology demonstration space mission for the Laser Interferometer Space Antenna (LISA), a space-based observatory for gravitational waves in the milli-Hertz band. Though the formal partnership between NASA and ESA to pursue LISA was dissolved in the Spring of 2011, ESA has recently selected the Gravitational Universe theme for its third Large-class mission (L3), to be fulfilled by a space-borne gravitational wave observatory. Any such mission will take advantage of the significant technology development efforts that have already been made, especially those of the LISA Pathfinder mission, which is being led and built by ESA, with significant NASA contributions. The mission will place two test masses in drag-free flight and measure the relative acceleration between them, in order to validate a number of technologies that are critical to LISA-like gravitational wave instruments. These include the sensing and control of the test masses, drag-free control laws, microNewton thrusters, and picometer-level laser metrology. With a launch date in the summer of 2015, LISA Pathfinder is currently in the late stages of integration. This talk presents the current status of the LISA Pathfinder mission and associated activities. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700