Astrophysics and Astronomy Commons^™

Ice Caves On Extraterrestrial Bodies: What Are The Prospects For Speleogenesis And Detection?, Penelope J. Boston

The International Workshop on Ice Caves

Potential mechanisms for creating cavities in icy extraterrestrial bodies have been tentatively explored by several authors. On one hand we have examples of mechanisms that create caves in water ice here on Earth. In addition, there may be unique mechanisms on other Solar System objects that do not occur on Earth but might produce cavities, e.g. sublimation of comets upon perihelion passage. The methods of detecting such cavities depend upon the nature of the icy body in question, the potential for orbital or landed missions to visit those bodies in the future, and remote or landed methods for detecting the …

Nonperturbative Renormalization Of Overlap Quark Bilinears On 2+1-Flavor Domain Wall Fermion Configurations, Zhaofeng Liu, Ying Chen, Shao-Jing Dong, Michael Glatzmaier, Ming Gong, Anyi Li, Keh-Fei Liu, Yi-Bo Yang, Jian-Bo Zhang

Physics and Astronomy Faculty Publications

We present renormalization constants of overlap quark bilinear operators on 2+1-flavor domain wall fermion configurations. . . .

For the remainder of the abstract, please visit: http://dx.doi.org/10.1103/PhysRevD.90.034505

Beam-Energy Dependence Of Charge Separation Along The Magnetic Field In Au+Au Collisions At Rhic, J. Kevin Adkins, Renee Fatemi, Suvarna Ramachandran, G. Webb, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer

Physics and Astronomy Faculty Publications

Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with …

Fast Radio Burst Discovered In The Arecibo Pulsar Alfa Survey, L. G. Spitler, J. M. Cordes, J. W.T. Hessels, D. R. Lorimer, M. A. Mclaughlin, S. Chatterjee, F. Crawford, J. S. Deneva, Fredrick Jenet

Physics & Astronomy Faculty Publications

Recent work has exploited pulsar survey data to identify temporally isolated, millisecond-duration radio bursts with large dispersion measures (DMs). These bursts have been interpreted as arising from a population of extragalactic sources, in which case they would provide unprecedented opportunities for probing the intergalactic medium; they may also be linked to new source classes. Until now, however, all so-called fast radio bursts (FRBs) have been detected with the Parkes radio telescope and its 13-beam receiver, casting some concern about the astrophysical nature of these signals. Here we present FRB 121102, the first FRB discovery from a geographic location other than …

A Physically-Based Type Ii Supernova Feedback Model In Sph Simulations, Keita Todoroki

UNLV Theses, Dissertations, Professional Papers, and Capstones

We implement and test a core-collapse Type II SN feedback that is physically motivated and produces good agreement with observations in galaxy formation simulations. The model includes both kinetic and thermal feedback, allowing wind particles to receive a velocity kick that mimics galactic winds and distributes mass and metallicity to the interstellar and intergalactic medium. We also include a phenomenological stellar feedback to study a possible enhancement of the efficiency of the SN-II feedback by creating lower-density ambient gas medium of the stellar populations by distribution of thermal energy. Our SN-II model is unique in the sense that it computes …

The Experiences Of Women In Post Graduate Physics And Astronomy Programs: The Roles Of Support, Career Goals, And Gendered Experiences, Ramón S. Barthelemy

Dissertations

In physics and astronomy the low representation of women is obvious at every stage of the educational pathway from undergraduate students to full professors. These low numbers perpetuate themselves by failing to create new mentors to foster the next generation of women. Women and men also have different experiences as they traverse into physics and astronomy careers. Women often experience chilly climates, discrimination, and challenges coordinating the demands of young families with their careers. In the literature exploring this topic, little focus is put on the experiences of women graduate students in physics and no focus is put on women …

A Spectroscopic Study Of Anomalous Stellar Populations In M67, Courtney Mcgahee

All Dissertations

A population of stars exists in the old, open cluster M67, whose photometry, color magnitude diagram locations and associated evolutionary states cannot be explained by current, standard single star evolution theory. These stars are often referred to as ``yellow straggler' stars. Yellow stragglers have been identified in multiple star clusters suggesting that these stars constitute a real population. Additionally, according to independent studies, at least some of the yellow straggler stars in M67 are likely cluster members. Therefore, cluster non-membership is not a sufficient explanation for the observed anomalous photometry of these stars. It is possible that the yellow stragglers …

Mars-Relevant Phosphate Minerals And Implications For Martian Habitability, Christopher Adcock

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation is comprised of three studies focused on martian phosphate availability, with an introductory chapter introducing and linking the three studies. Chapter two is on the subject of merrillite synthesis. Merrillite is an extraterrestrial Ca-phosphate mineral similar to the mineral whitlockite and is found as a dominant primary phosphate mineral in martian meteorites. The chapter includes methods of whitlockite and merrillite synthesis as well as a detailed characterization of the produced minerals and a mechanism by which charge balance can be maintained when merrillite is synthesized through dehydrogenation of whitlockite.

Chapter three presents the results of kinetic and thermodynamic …

A Statistical Study Of Magnetic Field Fluctuations In The Dayside Magnetosheath And Their Dependence On Upstream Solar Wind Conditions, A. P. Dimmock, K. Nykyri, T. I. Pulkkinen

Publications

The magnetosheath functions as a natural interface connecting the interplanetary and magnetospheric plasma. Since the magnetosheath houses the shocked solar wind, it is populated with abundant magnetic field turbulence which are generated both locally and externally. Although the steady state magnetosheath is to date relatively well understood, the same cannot be said of transient magnetic perturbations due to their kinetic nature and often complex and numerous generation mechanisms. The current manuscript presents a statistical study of magnetic field fluctuations in the dayside magnetosheath as a function of upstream solar wind conditions. We concentrate on the ambient higher-frequency fluctuations in the …

The Geocoronal H Α Cascade Component Determined From Geocoronal H Β Intensity Measurements, F. L. Roesler, E. J. Mierkiewicz, S. M. Nossal

Publications

"Geocoronal H α and H β intensity measurements using the Wisconsin H α Mapper Fabry-Perot are used to determine the intensity of the H α cascade component. From basic atomic physics and the work of Meier (1995), we show that the total cascade in geocoronal H α emission is 0.52 ± 0.03 times the geocoronal H β intensity, I(H β), for solar Lyman series excitation of geocoronal hydrogen. The results are consistent with the H α cascade measurements of Mierkiewicz et al. (2012), which were determined directly from the analysis of H α line profile measurements, and significantly narrow the …

Galaxy And Mass Assembly (Gama) : Stellar Mass Functions By Hubble Type., Lee S. Kelvin, Simon P. Driver, Aaron S. G. Robotham, Edward N. Taylor, Alister W. Graham, Mehmet Alpaslan, Ivan K. Baldry, Steven P. Bamford, Amanda E. Bauer, Joss Bland-Hawthorn, Michael J. I. Brown, Matthew Colless, Christopher J. Conselice, Benne W. Holwerda, Andrew M. Hopkins, Maritza A. Lara-Lopez, Jochen Liske, Angel R. Lopez-Sanchez, Jonathan Loveday, Peder Norberg, Steven Phillipps, Cristina C. Popescu, Matthew Prescott, Anne E. Sansom, Richard J. Tuffs

Faculty and Staff Scholarship

We present an estimate of the galaxy stellar mass function and its division by morphological type in the local (0.025 < z < 0.06) Universe. Adopting robust morphological classifications as previously presented (Kelvin et al.) for a sample of 3727 galaxies taken from the Galaxy And Mass Assembly survey, we define a local volume and stellar mass limited sub-sample of 2711 galaxies to a lower stellar mass limit of M=109.0M⊙ M=109.0M⊙ . We confirm that the galaxy stellar mass function is well described by a double-Schechter function given by M∗=1010.64M⊙ M∗=1010.64M⊙ , α1 = −0.43, ϕ∗1=4.18dex−1Mpc−3 ϕ1∗=4.18dex−1Mpc−3 , α2 = −1.50 and ϕ∗2=0.74dex−1Mpc−3 ϕ2∗=0.74dex−1Mpc−3 . The constituent morphological-type stellar mass functions are well sampled above our lower stellar mass limit, excepting the faint little blue spheroid population of galaxies. We find approximately 71+3−4 71−4+3 per cent of the stellar mass in the local Universe is found within spheroid-dominated galaxies; ellipticals and S0-Sas. The remaining 29+4−3 29−3+4 per cent falls predominantly within late-type disc-dominated systems, Sab-Scds and Sd-Irrs. Adopting reasonable bulge-to-total ratios implies that approximately half the stellar mass today resides in spheroidal structures, and half in disc structures. Within this local sample, we find approximate stellar mass proportions for E : S0-Sa : Sab-Scd : Sd-Irr of 34 : 37 : 24 : 5.

Suppression Of Υ Production In D + Au And Au + Au Collisions At √SNn = 200 Gev, James K. Adkins, Renee Fatemi, Wolfgang Korsch, Suvarna Ramachandran, L. Adamczyk, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev, A. Banerjee

Physics and Astronomy Faculty Publications

We report measurements of Υ meson production in p + p, d + Au, and Au + Au collisions using the STAR detector at RHIC. We compare the Υ yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d + Au data and in hot nuclear matter using Au + Au data separated into three centrality classes. Our p + p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Υ (1S + …

Illustrations And Supporting Texts For Sound Standing Waves Of Air Columns In Pipes In Introductory Physics Textbooks, Liang Zeng, Chris Smith, G. Herold Poelzer, Jennifer Rodriguez, Edgar Corpuz, George Yanev

Physics & Astronomy Faculty Publications

In our pilot studies, we found that many introductory physics textbook illustrations with supporting text for sound standing waves of air columns in open-open, open-closed, and closed-closed pipes inhibit student understanding of sound standing wave phenomena due to student misunderstanding of how air molecules move within these pipes. Based on the construct of meaningful learning from cognitive psychology and semiotics, a quasiexperimental study was conducted to investigate the comparative effectiveness of two alternative approaches to student understanding: a traditional textbook illustration approach versus a newly designed air molecule motion illustration approach. Thirty volunteer students from introductory physics classes were randomly …

The Magnetopause: Bringing Space Physics Into A Junior Lab, Jim Crumley, Ari Palczewski,, Stephen Kaster

MapCores Faculty Publications

Undergraduate students often have minimal exposure to many subfields
of physics which are active areas of research. Space physics
is an area that is particularly difficult to expose students to since
it builds off of another area that most undergraduates see little of,
plasma physics. The magnetopause is convenient entry point
into space physics, since it can be modeled as a pressure balance, which is
a concept familiar from introductory physics. We use the Earth's
magnetopause as the basis for a lab for junior physics majors. In
the lab students analyze results from a NASA MHD simulation and
data from …

Warm Ice Giant Gj 3470b – Ii. Revised Planetary And Stellar Parameters From Optical To Near-Infrared Transit Photometry, Lauren I. Biddle, Kyle A. Pearson, Ian J. M. Crossfield, Benjamin J. Fulton, Simona Ciceri, Jason Eastman, Travis Barman, Andrew W. Mann, Gregory W. Henry, Andrew W. Howard, Michael H. Williamson, Evan Sinukoff, Diana Dragomir, Laura Vican, Luigi Mancini, John Southworth, Adam Greenberg, Jake D. Turner, Robert Thompson, Brian W. Taylor, Stephen E. Levine, Matthew W. Webber

Information Systems and Engineering Management Research Publications

It is important to explore the diversity of characteristics of low-mass, low-density planets to understand the nature and evolution of this class of planets. We present a homogeneous analysis of 12 new and 9 previously published broad-band photometric observations of the Uranus-sized extrasolar planet GJ 3470b, which belongs to the growing sample of sub-Jovian bodies orbiting M dwarfs. The consistency of our analysis explains some of the discrepancies between previously published results and provides updated constraints on the planetary parameters. Our data are also consistent with previous transit observations of this system. The physical properties of the transiting system can …

Candels+3d-Hst: Compact Sfgs At Z ~ 2-3, The Progenitors Of The First Quiescent Galaxies, G. Barro, S. M. Faber, P. G. Pérez-González, C. Pacifici, J. R. Trump, D. C. Koo, S. Wuyts, Y. Guo, E. Bell, A. Dekel, L. Porter, J. Primack, H. Ferguson, M. L. N. Ashby, K. Caputi, D. Ceverino, D. Croton, G. G. Fazio, M. Giavalisco, L. Hsu, Dalibor D. Kocevski, A. Koekemoer, P. Kurcynski, P. Kollipara, J. Lee, D. H. Mcintosh, E. Mcgrath, C. Moody, R. Somerville, C. Papovich, M. Salvato, P. Santini, T. Tal, A. Van Der Wel, C. C. Williams, S. P. Willner, A. Zolotov

Physics and Astronomy Faculty Publications

We analyze the star-forming and structural properties of 45 massive (log(M/M _☉) >10) compact star-forming galaxies (SFGs) at 2 < z < 3 to explore whether they are progenitors of compact quiescent galaxies at z ~ 2. The optical/NIR and far-IR Spitzer/Herschel colors indicate that most compact SFGs are heavily obscured. Nearly half (47%) host an X-ray-bright active galactic nucleus (AGN). In contrast, only about 10% of other massive galaxies at that time host AGNs. Compact SFGs have centrally concentrated light profiles and spheroidal morphologies similar to quiescent galaxies and are thus strikingly different from other SFGs, which typically are disk-like and sometimes clumpy or irregular. Most compact …

Nonadiabatic Heating In Magnetic Reconnection, Xuanye Ma, Antonius Otto

Publications

Plasma transport process as a fundamental problem in magnetospheric physics is often associated with strong nonadiabatic heating. At the magnetopause, observations show an increase of specific entropy (i.e., S = p/ργ) by 2 orders of magnitude from the magnetosheath into the magnetosphere. In the near‐Earth magnetotail, particle injection requires strongly entropy depleted plasma bubbles, and their evolution can be strongly modified in the presence of nonadiabatic heating. In this study, one of the critical plasma transport mechanisms, magnetic reconnection, is investigated as a nonadiabatic process in the framework of MHD. It is important to examine whether magnetic reconnection can provide …

Electron-Ion Equilibrium And Shock Precursors In The Northeast Limb Of The Cygnus Loop, Amber A. Medina, John C. Raymond, Richard J. Edgar, Nelson Caldwell, Robert A. Fesen, Dan Milisavljevic

Dartmouth Scholarship

We present an observational study using high-resolution echelle spectroscopy of collisionless shocks in the Cygnus Loop supernova remnant. Measured Hα line profiles constrain pre-shock heating processes, shock speeds, and electron-ion equilibration (T_e /T_i ). The shocks produce faint Hα emission line profiles, which are characterized by narrow and broad components. The narrow component is representative of the pre-shock conditions, while the broad component is produced after charge transfer between neutrals entering the shock and protons in the post-shock gas, thus reflecting the properties of the post-shock gas. We observe a diffuse Hα region extending about 25 …

The Violent Youth Of Bright And Massive Cluster Galaxies And Their Maturation Over 7 Billion Years, B. Ascaso, B. C. Lemaux, L. M. Lubin, R. R. Gal, Dale D. Kocevski, N. Rumbaugh, G. Squires

Physics and Astronomy Faculty Publications

In this study, we investigate the formation and evolution mechanisms of the brightest cluster galaxies (BCGs) over cosmic time. At high redshift (z ∼ 0.9), we selected BCGs and most massive cluster galaxies (MMCGs) from the Cl1604 supercluster and compared them to low-redshift (z ∼ 0.1) counterparts drawn from the MCXC meta-catalogue, supplemented by Sloan Digital Sky Survey imaging and spectroscopy. We observed striking differences in the morphological, colour, spectral, and stellar mass properties of the BCGs/MMCGs in the two samples. High-redshift BCGs/MMCGs were, in many cases, star-forming, late-type galaxies, with blue broad-band colours, properties largely absent amongst …

Heliospheric Influence On The Anisotropy Of Tev Cosmic Rays, Ming Zhang, Pingbing Zuo, Nikolai Pogorelov

Aerospace, Physics, and Space Science Faculty Publications

This paper provides a theory of using Liouville's theorem to map the anisotropy of TeV cosmic rays seen at Earth using the particle distribution function in the local interstellar medium (LISM). The ultimate source of cosmic ray anisotropy is the energy, pitch angle, and spatial dependence of the cosmic ray distribution function in the LISM. Because young nearby cosmic ray sources can make a special contribution to the cosmic ray anisotropy, the anisotropy depends on the source age, distance and magnetic connection, and particle diffusion of these cosmic rays, all of which make the anisotropy sensitive to the particle energy. …