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Articles 3691 - 3720 of 8858

Full-Text Articles in Astrophysics and Astronomy

Discipline-Based Planetary Education Research And Computational Fluid Dynamics Analysis Of Mars, Filis Coba Jul 2016

Discipline-Based Planetary Education Research And Computational Fluid Dynamics Analysis Of Mars, Filis Coba

Physics Theses & Dissertations

This thesis originates from the testing and implementation of an IRB-approved interactive animation designed to help students understand what causes The Reasons For The Seasons (RFTS) on Earth. Results from the testing indicated a small improvement in student understanding after exposure to the animation. Next, using the 3-D mapping tool Google Earth, students explored seasons and other planetary features on Mercury, Venus, the Moon and Mars through IRB-approved interactive tours which were developed and tested for astronomy education. Results from the tests indicated that there were statistically significant learning gains (p-value < 0.05) after students interacted with the tours compared to those who did not. The development of the tours inspired a geophysics study of the possibility of former plate motion (or plate tectonics) on Mars. A 2-D finite element convection model for the mantle of Mars was designed and solved using COMSOL Multiphysics 5.1, to investigate whether or not thermal gradients in a Mars-sized planet could cause vigorous upper mantle convection, consistent with plate tectonic processes. Results from this project indicated that stable convection could occur in the interior of a Mars-like planet assuming the presence of sufficiently high thermal gradients at about 0.8 times the mantle temperature of Earth. The convective patterns resembled hot upwelling and cool downwelling which may be similar to subduction-like features. Furthermore, increasing the temperature of the hot boundaries resulted in faster, more rigorous convective motions and a hotter average temperature.

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Emission From Black Holes And Supernovae In The Early Universe, Brandon Kerry Wiggins Jul 2016

Emission From Black Holes And Supernovae In The Early Universe, Brandon Kerry Wiggins

Theses and Dissertations

To constrain the era when the first galaxies and stars appeared upcoming instruments will rely on the brightest events in the universe: supernovae and brilliant emission from massive black holes. In this dissertation, we investigate the observability of certain types of supernovae of the very first stars (Population III stars) and find that while these events are sufficiently luminous to be observed with deep-sky instruments such as the James Webb Space Telescope (JWST), they may not observe these particular types of events in their lifetimes. We next explore the origins of massive black holes and introduce the direct collapse hypothesis …

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Galaxy And Mass Assembly : Accurate Panchromatic Photometry From Optical Priors Using Lambdar., A. H. Wright, A. S. G. Robotham, N. Bourne, S. P. Driver, L. Dunne, S. J. Maddox, M. Alpaslan, S. K. Andrews, A. E. Bauer, J. Bland-Hawthorn, Sarah Brough, M. J. I. Brown, C. Clarke, Michelle Cluver, L. J. M. Davies, M. W. Grootes, Benne W. Holwerda, A. M. Hopkins, T. H. Jarrett, Prajwal R. Kafle, Rebecca Lange, J. Liske, J. Loveday, A. J. Moffett, P. Norberg, C. C. Popescu, M. Smith, E. N. Taylor, R. J. Tuffs, L. Wang, S. M. Wilkins Jul 2016

Galaxy And Mass Assembly : Accurate Panchromatic Photometry From Optical Priors Using Lambdar., A. H. Wright, A. S. G. Robotham, N. Bourne, S. P. Driver, L. Dunne, S. J. Maddox, M. Alpaslan, S. K. Andrews, A. E. Bauer, J. Bland-Hawthorn, Sarah Brough, M. J. I. Brown, C. Clarke, Michelle Cluver, L. J. M. Davies, M. W. Grootes, Benne W. Holwerda, A. M. Hopkins, T. H. Jarrett, Prajwal R. Kafle, Rebecca Lange, J. Liske, J. Loveday, A. J. Moffett, P. Norberg, C. C. Popescu, M. Smith, E. N. Taylor, R. J. Tuffs, L. Wang, S. M. Wilkins

Faculty and Staff Scholarship

We present the Lambda Adaptive Multi-Band Deblending Algorithm in R (LAMBDAR), a novel code for calculating matched aperture photometry across images that are neither pixel- nor PSF-matched, using prior aperture definitions derived from high-resolution optical imaging. The development of this program is motivated by the desire for consistent photometry and uncertainties across large ranges of photometric imaging, for use in calculating spectral energy distributions. We describe the program, specifically key features required for robust determination of panchromatic photometry: propagation of apertures to images with arbitrary resolution, local background estimation, aperture normalization, uncertainty determination and propagation, and object deblending. Using simulated …

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Wise X Supercosmos Photometric Redshift Catalog : 20 Million Galaxies Over 3pi Steradians., Maciej Bilicki, John A. Peacock, T. H. Jarrett, Michelle Cluver, Natasha Maddox, Michael J. I. Brown, Edward N. Taylor, Nigel C. Hambly, Aleksandra Solarz, Benne W. Holwerda, Ivan K. Baldry, Jon Loveday, Amanda J. Moffett, Andrew M. Hopkins, Simon P. Driver, Mehmet Alpaslan, Joss Bland-Hawthorn Jul 2016

Wise X Supercosmos Photometric Redshift Catalog : 20 Million Galaxies Over 3pi Steradians., Maciej Bilicki, John A. Peacock, T. H. Jarrett, Michelle Cluver, Natasha Maddox, Michael J. I. Brown, Edward N. Taylor, Nigel C. Hambly, Aleksandra Solarz, Benne W. Holwerda, Ivan K. Baldry, Jon Loveday, Amanda J. Moffett, Andrew M. Hopkins, Simon P. Driver, Mehmet Alpaslan, Joss Bland-Hawthorn

Faculty and Staff Scholarship

We cross-match the two currently largest all-sky photometric catalogs—mid-infrared Wide-field Infrared Survey Explorer and SuperCOSMOS scans of UKST/POSS-II photographic plates—to obtain a new galaxy sample that covers 3π steradians. In order to characterize and purify the extragalactic data set, we use external GAMA and Sloan Digital Sky Survey spectroscopic information to define quasar and star loci in multicolor space, aiding the removal of contamination from our extended source catalog. After appropriate data cleaning, we obtain a deep wide-angle galaxy sample that is approximately 95% pure and 90% complete at high Galactic latitudes. The catalog contains close to 20 million galaxies …

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Erratum: “Milky Way Red Dwarfs In The Borg Survey; Galactic Scale-Height And The Distribution Of Dwarfs Stars In Wfc3 Imaging"., Benne W. Holwerda, M. Trenti, W. Clarkson, K. Sahu, L. Bradley, M. Stiavelli, N. Pirzkal, G. De Marchi, M. Andersen, R. J. Bouwens, R. Ryan, I. Van Vledder, D. Van Der Vlugt Jul 2016

Erratum: “Milky Way Red Dwarfs In The Borg Survey; Galactic Scale-Height And The Distribution Of Dwarfs Stars In Wfc3 Imaging"., Benne W. Holwerda, M. Trenti, W. Clarkson, K. Sahu, L. Bradley, M. Stiavelli, N. Pirzkal, G. De Marchi, M. Andersen, R. J. Bouwens, R. Ryan, I. Van Vledder, D. Van Der Vlugt

Faculty and Staff Scholarship

In the catalog of M-dwarfs presented in Holwerda et al. (2014, H14 hereafter), there is an issue with the conversion from celestial coordinates to Galactic ones, done with PYEPHEM a wrapper around a trusted and vetted library ephermis. Here we present the corrected coordinates (using ASTROPY) and distances based on AB magnitudes. We have amended the tables and figures accordingly. The relation between vertical scale-height (z0) and M- dwarf subtype found in H14 is no longer present. We find a scale-height of 600 pc for all types, in part due to the presence of a second Galactic structural component.

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Supplement:“Localization And Broadband Follow-Up Of The Gravitational-Wave Transient Gw150914”(2016, Apjl, 826, L13), B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, Martin Beroiz, T. Peñuela, Nicolas A. Pereyra, Matthew Benacquista Jul 2016

Supplement:“Localization And Broadband Follow-Up Of The Gravitational-Wave Transient Gw150914”(2016, Apjl, 826, L13), B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, Martin Beroiz, T. Peñuela, Nicolas A. Pereyra, Matthew Benacquista

Physics & Astronomy Faculty Publications

This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands.

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Supplement: "Localization And Broadband Follow-Up Of The Gravitational-Wave Transient Gw150914" (2016, Apjl, 826, L13), B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, B. Allen, A. Allocca, P. A. Altin, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. C. Arceneaux, J. S. Areeda, N. Arnaud, K. G. Arun, S. Ascenzi, Tiffany Z. Summerscales Jul 2016

Supplement: "Localization And Broadband Follow-Up Of The Gravitational-Wave Transient Gw150914" (2016, Apjl, 826, L13), B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, B. Allen, A. Allocca, P. A. Altin, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. C. Arceneaux, J. S. Areeda, N. Arnaud, K. G. Arun, S. Ascenzi, Tiffany Z. Summerscales

Faculty Publications

© 2016. The American Astronomical Society. All rights reserved. This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands.

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Holographic Chern-Simons Defects, Mitsutoshi Fujita, Charles M. Melby-Thompson, René Meyer, Shigeki Sugimoto Jun 2016

Holographic Chern-Simons Defects, Mitsutoshi Fujita, Charles M. Melby-Thompson, René Meyer, Shigeki Sugimoto

Physics and Astronomy Faculty Publications

We study SU(N ) Yang-Mills-Chern-Simons theory in the presence of defects that shift the Chern-Simons level from a holographic point of view by embedding the system in string theory. The model is a D3-D7 system in Type IIB string theory, whose gravity dual is given by the AdS soliton background with probe D7 branes attaching to the AdS boundary along the defects. We holographically renormalize the free energy of the defect system with sources, from which we obtain the correlation functions for certain operators naturally associated to these defects. We find interesting phase transitions when the separation of the …

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Ultraviolet Emission Lines Of Si Ii In Quasars—Investigating The "Si Ii Disaster", Sibasish Laha, Francis P. Keenan, Gary J. Ferland, Catherine A. Ramsbottom, Kanti M. Aggarwal Jun 2016

Ultraviolet Emission Lines Of Si Ii In Quasars—Investigating The "Si Ii Disaster", Sibasish Laha, Francis P. Keenan, Gary J. Ferland, Catherine A. Ramsbottom, Kanti M. Aggarwal

Physics and Astronomy Faculty Publications

The observed line intensity ratios of the Si II λ1263 and λ1307 multiplets to that of Si II λ1814 in the broad-line region (BLR) of quasars are both an order of magnitude larger than the theoretical values. This was first pointed out by Baldwin et al., who termed it the "Si II disaster," and it has remained unresolved. We investigate the problem in the light of newly published atomic data for Si II. Specifically, we perform BLR calculations using several different atomic data sets within the CLOUDY modeling code under optically thick quasar cloud conditions. In addition, …

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Orion's Veil: Magnetic Field Strengths And Other Properties Of A Pdr In Front Of The Trapezium Cluster, Thomas H. Troland, W. M. Goss, C. L. Brogan, R. M. Crutcher, D. A. Roberts Jun 2016

Orion's Veil: Magnetic Field Strengths And Other Properties Of A Pdr In Front Of The Trapezium Cluster, Thomas H. Troland, W. M. Goss, C. L. Brogan, R. M. Crutcher, D. A. Roberts

Physics and Astronomy Faculty Publications

We present an analysis of physical conditions in the Orion Veil, an atomic photon-dominated region (PDR) that lies just in front (≈2 pc) of the Trapezium stars of Orion. This region offers an unusual opportunity to study the properties of PDRs, including the magnetic field. We have obtained 21 cm H i and 18 cm (1665 and 1667 MHz) OH Zeeman effect data that yield images of the line-of-sight magnetic field strength B los in atomic and molecular regions of the Veil. We find B los ≈ −50 to −75 μG in the atomic gas across much of the …

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A Combined Spectroscopic And Photometric Stellar Activity Study Of Epsilon Eridani, Matthew J. Giguere, Debra A. Fischer, Cyril X. Y. Zhang, Jaymie M. Matthews, Chris Cameron, Gregory W. Henry Jun 2016

A Combined Spectroscopic And Photometric Stellar Activity Study Of Epsilon Eridani, Matthew J. Giguere, Debra A. Fischer, Cyril X. Y. Zhang, Jaymie M. Matthews, Chris Cameron, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We present simultaneous ground-based radial velocity (RV) measurements and space-based photometric measurements of the young and active K dwarf Epsilon Eridani. These measurements provide a data set for exploring methods of identifying and ultimately distinguishing stellar photospheric velocities from Keplerian motion. We compare three methods we have used in exploring this data set: Dalmatian, an MCMC spot modeling code that fits photometric and RV measurements simultaneously; the FF' method, which uses photometric measurements to predict the stellar activity signal in simultaneous RV measurements; and Hα analysis. We show that our Hα measurements are strongly correlated with the Microvariability and Oscillations …

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High-Energy Neutrino Follow-Up Search Of Gravitational Wave Event Gw150914 With Antares And Icecube, S. Adrián-Martínez, A. Albert, M. André, H. P. Daveloza, Joey S. Key, S. R. Morriss, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano Jun 2016

High-Energy Neutrino Follow-Up Search Of Gravitational Wave Event Gw150914 With Antares And Icecube, S. Adrián-Martínez, A. Albert, M. André, H. P. Daveloza, Joey S. Key, S. R. Morriss, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

We present the high-energy-neutrino follow-up observations of the first gravitational wave transient GW150914 observed by the Advanced LIGO detectors on September 14, 2015. We search for coincident neutrino candidates within the data recorded by the IceCube and Antares neutrino detectors. A possible joint detection could be used in targeted electromagnetic follow-up observations, given the significantly better angular resolution of neutrino events compared to gravitational waves. We find no neutrino candidates in both temporal and spatial coincidence with the gravitational wave event. Within ±500 s of the gravitational wave event, the number of neutrino candidates detected by IceCube and Antares were …

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High-Energy Neutrino Follow-Up Search Of Gravitational Wave Event Gw150914 With Antares And Icecube, S. Adrián-Martínez, A. Albert, M. André, M. Anghinolfi, G. Anton, M. Ardid, J. J. Aubert, T. Avgitas, B. Baret, J. Barrios-Martí, S. Basa, V. Bertin, S. Biagi, R. Bormuth, M. C. Bouwhuis, R. Bruijn, J. Brunner, J. Busto, A. Capone, L. Caramete, J. Carr, S. Celli, T. Chiarusi, M. Circella, A. Coleiro, R. Coniglione, H. Costantini, P. Coyle, A. Creusot, A. Deschamps, G. De Bonis, Tiffany Z. Summerscales Jun 2016

High-Energy Neutrino Follow-Up Search Of Gravitational Wave Event Gw150914 With Antares And Icecube, S. Adrián-Martínez, A. Albert, M. André, M. Anghinolfi, G. Anton, M. Ardid, J. J. Aubert, T. Avgitas, B. Baret, J. Barrios-Martí, S. Basa, V. Bertin, S. Biagi, R. Bormuth, M. C. Bouwhuis, R. Bruijn, J. Brunner, J. Busto, A. Capone, L. Caramete, J. Carr, S. Celli, T. Chiarusi, M. Circella, A. Coleiro, R. Coniglione, H. Costantini, P. Coyle, A. Creusot, A. Deschamps, G. De Bonis, Tiffany Z. Summerscales

Faculty Publications

© 2016 American Physical Society. We present the high-energy-neutrino follow-up observations of the first gravitational wave transient GW150914 observed by the Advanced LIGO detectors on September 14, 2015. We search for coincident neutrino candidates within the data recorded by the IceCube and Antares neutrino detectors. A possible joint detection could be used in targeted electromagnetic follow-up observations, given the significantly better angular resolution of neutrino events compared to gravitational waves. We find no neutrino candidates in both temporal and spatial coincidence with the gravitational wave event. Within ±500 s of the gravitational wave event, the number of neutrino candidates detected …

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Living In The Milky Way, Ian R. Clarke Jun 2016

Living In The Milky Way, Ian R. Clarke

Physics and Astronomy Faculty Publications

It’s finally here. Today, June 20 at 6:34 p.m., is the the summer solstice, also known as the first day of summer and, confusingly enough, midsummer’s eve. From a scientific perspective, it marks the moment the sun reaches its northernmost point in our sky. As a result of that position, it’s the shortest night and longest day if you live north of the equator. [excerpt]

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Evidence For Fluorescent Fe Ii Emission From Extended Low Ionization Outflows In Obscured Quasars, Tinggui Wang, Gary J. Ferland, Chenwei Yang, Huiyuan Wang, Shaohua Zhang Jun 2016

Evidence For Fluorescent Fe Ii Emission From Extended Low Ionization Outflows In Obscured Quasars, Tinggui Wang, Gary J. Ferland, Chenwei Yang, Huiyuan Wang, Shaohua Zhang

Physics and Astronomy Faculty Publications

Recent studies have shown that outflows in at least some broad absorption line (BAL) quasars are extended well beyond the putative dusty torus. Such outflows should be detectable in obscured quasars. We present four WISE selected infrared red quasars with very strong and peculiar ultraviolet Fe II emission lines: strong UV Fe II UV arising from transitions to ground/low excitation levels, and very weak Fe II at wavelengths longer than 2800 Å. The spectra of these quasars display strong resonant emission lines, such as C IV, Al III and Mg II but sometimes, a lack of non-resonant lines such as …

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Search For Transient Gravitational Waves In Coincidence With Short-Duration Radio Transients During 2007-2013, B. P. Abbott, R. Abbott, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano Jun 2016

Search For Transient Gravitational Waves In Coincidence With Short-Duration Radio Transients During 2007-2013, B. P. Abbott, R. Abbott, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

We present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo, and GEO interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes fast radio bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short-duration radio signals and transient gravitational-wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational-wave emission in coincidence with these radio transients was found, the …

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Plasma Transport Driven By The Rayleigh-Taylor Instability, X. Ma, P. A. Delamere, A. Otto Jun 2016

Plasma Transport Driven By The Rayleigh-Taylor Instability, X. Ma, P. A. Delamere, A. Otto

Publications

Two important differences between the giant magnetospheres (i.e., Jupiter's and Saturn's magnetospheres) and the terrestrial magnetosphere are the internal plasma sources and the fast planetary rotation. Thus, there must be a radially outward flow to transport the plasma to avoid infinite accumulation of plasma. This radial outflow also carries the magnetic flux away from the inner magnetosphere due to the frozen‐in condition. As such, there also must be a radial inward flow to refill the magnetic flux in the inner magnetosphere. Due to the similarity between Rayleigh‐Taylor (RT) instability and the centrifugal instability, we use a three‐dimensional RT instability to …

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Gw151226: Observation Of Gravitational Waves From A 22-Solar-Mass Binary Black Hole Coalescence, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al. Jun 2016

Gw151226: Observation Of Gravitational Waves From A 22-Solar-Mass Binary Black Hole Coalescence, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al.

Publications

We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5 σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 …

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Properties Of The Binary Black Hole Merger Gw150914, B. P. Abbott, R. Abbott, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov Jun 2016

Properties Of The Binary Black Hole Merger Gw150914, B. P. Abbott, R. Abbott, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

On September 14, 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected a gravitational-wave transient (GW150914); we characterize the properties of the source and its parameters. The data around the time of the event were analyzed coherently across the LIGO network using a suite of accurate waveform models that describe gravitational waves from a compact binary system in general relativity. GW150914 was produced by a nearly equal mass binary black hole of masses 3⁢6+5−4⁢��⊙ and 2⁢9+4−4⁢��⊙; for each parameter we report the median value and the range of the 90% credible interval. The dimensionless spin magnitude of the more massive black …

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Gw151226: Observation Of Gravitational Waves From A 22-Solar-Mass Binary Black Hole Coalescence, B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano Jun 2016

Gw151226: Observation Of Gravitational Waves From A 22-Solar-Mass Binary Black Hole Coalescence, B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, …

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A Cyclic Universe Approach To Fine Tuning, Stephon Alexander, Sam Cormack, Marcelo Gleiser Jun 2016

A Cyclic Universe Approach To Fine Tuning, Stephon Alexander, Sam Cormack, Marcelo Gleiser

Dartmouth Scholarship

We present a closed bouncing universe model where the value of coupling constants is set by the dynamics of a ghost-like dilatonic scalar field. We show that adding a periodic potential for the scalar field leads to a cyclic Friedmann universe where the values of the couplings vary randomly from one cycle to the next. While the shuffling of values for the couplings happens during the bounce, within each cycle their time-dependence remains safely within present observational bounds for physically-motivated values of the model parameters. Our model presents an alternative to solutions of the fine tuning problem based on string …

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Quantum Information In Rydberg-Dressed Atoms, Tyler Emerson Keating Jun 2016

Quantum Information In Rydberg-Dressed Atoms, Tyler Emerson Keating

Physics & Astronomy ETDs

In any physical platform, two ingredients are essential for quantum information processing: single-qubit control, and entangling interactions between qubits. Neutral atoms can be individually controlled with high fidelity and are resilient to environmental noise, making them attractive candidates for implementing quantum information protocols. However, achieving strong interactions remains a major obstacle. One way to increase the interaction strength between neutral atoms is to excite them into high-lying Rydberg states, which exhibit large electric dipole moments (and by extension, strong electric dipole-dipole interactions). By slowly ramping up the Rydberg level coupling in a system, one can "dress'' the atomic ground states …

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Analytic Models Of Brown Dwarfs And The Substellar Mass Limit, Sree Ram Valluri, Shantanu Basu, Sayantan Auddy Jun 2016

Analytic Models Of Brown Dwarfs And The Substellar Mass Limit, Sree Ram Valluri, Shantanu Basu, Sayantan Auddy

Physics and Astronomy Publications

We present the analytic theory of brown dwarf evolution and the lower mass limit of the hydrogen burning main-sequence stars and introduce some modifications to the existing models. We give an exact expression for the pressure of an ideal nonrelativistic Fermi gas at a finite temperature, therefore allowing for nonzero values of the degeneracy parameter. We review the derivation of surface luminosity using an entropy matching condition and the first-order phase transition between the molecular hydrogen in the outer envelope and the partially ionized hydrogen in the inner region.We also discuss the results of modern simulations of the plasma phase …

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Hst Imaging Of The Dusty Filaments And Nucleus Swirl In Ngc4696 At The Centre Of The Centaurus Cluster, A. C. Fabian, S. A. Walker, H. R. Russell, C. Pinto, R. E. A. Canning, P. Salome, J. S. Sanders, G. B. Taylor, E. G. Zweibel, C. J. Conselice, F. Combes, C. S. Crawford, Gary J. Ferland, J. S. Gallagher Iii, N. A. Hatch, R. M. Johnstone, C. S. Reynolds Jun 2016

Hst Imaging Of The Dusty Filaments And Nucleus Swirl In Ngc4696 At The Centre Of The Centaurus Cluster, A. C. Fabian, S. A. Walker, H. R. Russell, C. Pinto, R. E. A. Canning, P. Salome, J. S. Sanders, G. B. Taylor, E. G. Zweibel, C. J. Conselice, F. Combes, C. S. Crawford, Gary J. Ferland, J. S. Gallagher Iii, N. A. Hatch, R. M. Johnstone, C. S. Reynolds

Physics and Astronomy Faculty Publications

Narrow-band HST imaging has resolved the detailed internal structure of the 10 kpc diameter H α+[N II] emission line nebulosity in NGC4696, the central galaxy in the nearby Centaurus cluster, showing that the dusty, molecular, filaments have a width of about 60 pc. Optical morphology and velocity measurements indicate that the filaments are dragged out by the bubbling action of the radio source as part of the active galactic nucleus feedback cycle. Using the drag force we find that the magnetic field in the filaments is in approximate pressure equipartition with the hot gas. The filamentary nature of the …

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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 Jun 2016

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 …

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Observing Gravitational-Wave Transient Gw150914 With Minimal Assumptions, B. P. Abbott, K. Gill, B. Hughey, M. Szczepańczyk, M. Zanolin, Et Al. Jun 2016

Observing Gravitational-Wave Transient Gw150914 With Minimal Assumptions, B. P. Abbott, K. Gill, B. Hughey, M. Szczepańczyk, M. Zanolin, Et Al.

Publications

The gravitational-wave signal GW150914 was first identified on September 14, 2015, by searches for short-duration gravitational-wave transients. These searches identify time-correlated transients in multiple detectors with minimal assumptions about the signal morphology, allowing them to be sensitive to gravitational waves emitted by a wide range of sources including binary black hole mergers. Over the observational period from September 12 to October 20, 2015, these transient searches were sensitive to binary black hole mergers similar to GW150914 to an average distance of ∼600  Mpc. In this paper, we describe the analyses that first detected GW150914 as well as the parameter estimation …

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Gw150914: First Results From The Search For Binary Black Hole Coalescence With Advanced Ligo, B. P. Abbott, R. Abbott, T. D. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov Jun 2016

Gw150914: First Results From The Search For Binary Black Hole Coalescence With Advanced Ligo, B. P. Abbott, R. Abbott, T. D. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

On September 14, 2015, at 0950:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015 GW150914 was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.

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Observing Gravitational-Wave Transient Gw150914 With Minimal Assumptions, B. P. Abbott, R. Abbott, T. D. Abbott, Mario C. Diaz, Joey S. Key, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov Jun 2016

Observing Gravitational-Wave Transient Gw150914 With Minimal Assumptions, B. P. Abbott, R. Abbott, T. D. Abbott, Mario C. Diaz, Joey S. Key, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

The gravitational-wave signal GW150914 was first identified on September 14, 2015, by searches for short-duration gravitational-wave transients. These searches identify time-correlated transients in multiple detectors with minimal assumptions about the signal morphology, allowing them to be sensitive to gravitational waves emitted by a wide range of sources including binary black hole mergers. Over the observational period from September 12 to October 20, 2015, these transient searches were sensitive to binary black hole mergers similar to GW150914 to an average distance of ∼600 Mpc. In this paper, we describe the analyses that first detected GW150914 as well as the parameter estimation …

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Absolute Properties Of The Pre-Main-Sequence Eclipsing Binary Star Np Persei, Claud H. Sandberg Lacy, Francis C. Fekel, Krešimir Pavlovski, Guillermo Torres, Matthew W. Muterspaugh Jun 2016

Absolute Properties Of The Pre-Main-Sequence Eclipsing Binary Star Np Persei, Claud H. Sandberg Lacy, Francis C. Fekel, Krešimir Pavlovski, Guillermo Torres, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

NP Per is a well-detached, 2.2 day eclipsing binary whose components are both pre-main-sequence stars that are still contracting toward the main-sequence phase of evolution. We report extensive photometric and spectroscopic observations with which we have determined their properties accurately. Their surface temperatures are quite different: 6420 ± 90 K for the larger F5 primary star and 4540 ± 160 K for the smaller K5e star. Their masses and radii are 1.3207 ± 0.0087 solar masses and 1.372 ± 0.013 solar radii for the primary, and 1.0456 ± 0.0046 solar masses and 1.229 ± 0.013 solar radii for the secondary. …

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Characterization Of Transient Noise In Advanced Ligo Relevant To Gravitational Wave Signal Gw150914, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al. Jun 2016

Characterization Of Transient Noise In Advanced Ligo Relevant To Gravitational Wave Signal Gw150914, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al.

Publications

On September 14, 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal.

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