Astrophysics and Astronomy Commons^™

Impact Of Weak Gravitational Force In Sri Lanka, Periyandy Thunendran

International Programs

Gravity studies explain about the sub surface features and shape of the earth, and show gravitational force is weak in the Sri Lanka region, which has positive and negative impacts. This poster argues further studies on gravity are needed to revise the global gravitational model of the region.

Wallaby Pre-Pilot Survey: Two Dark Clouds In The Vicinity Of Ngc 1395, O. I. Wong, A. R. H. Stevens, B. Q. For, Tobias Westmeier, M. Dixon, S. -H. Oh, G. I. G. Jozsa, T. N. Reynolds, K. Lee-Waddell, Juan P. Madrid

Physics & Astronomy Faculty Publications

We present the Australian Square Kilometre Array Pathfinder (ASKAP) WALLABY pre-pilot observations of two ‘dark’ HI sources (with HI masses of a few times 108 M⊙ and no known stellar counterpart) that reside within 363 kpc of NGC 1395, the most massive early-type galaxy in the Eridanus group of galaxies. We investigate whether these ‘dark’ HI sources have resulted from past tidal interactions or whether they are an extreme class of low surface brightness galaxies. Our results suggest that both scenarios are possible, and not mutually exclusive. The two ‘dark’ HI sources are compact, reside in relative isolation and are …

Wallaby Pre-Pilot Survey: H I Content Of The Eridanus Supergroup, B. Q. For, J. Wang, Tobias Westmeier, O. I. Wong, C. Murugeshan, L. Staveley-Smith, H. M. Courtois, D. Pomarede, Juan P. Madrid

Physics & Astronomy Faculty Publications

We present observations of the Eridanus supergroup obtained with the Australian Square Kilometre Array Pathfinder (ASKAP) as part of the pre-pilot survey for the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY). The total number of detected H I sources is 55, of which 12 are background galaxies not associated with the Eridanus supergroup. Two massive H I clouds are identified and large H I debris fields are seen in the NGC 1359 interacting galaxy pair, and the face-on spiral galaxy NGC 1385. We describe the data products from the source finding algorithm and present the basic parameters. The …

Planetarium Open For Shows Once Again, Erik Johnson

Natural Science Faculty

After nearly 17 months of closure due to the COVID-19 pandemic, the William M. Staerkel Planetarium at Parkland College has reopened for public shows.

Free-Free Absorption In Hot Relativistic Flows: Application To Fast Radio Bursts, Esha Kundu, Bing Zhang

Physics & Astronomy Faculty Research

Magnetic flares create hot relativistic shocks outside the light cylinder radius of a magnetized star. Radio emission produced in such a shock or at a radius smaller than the shock undergoes free–free absorption while passing through the shocked medium. In this work, we demonstrate that this free–free absorption can lead to a negative drift in the frequency-time spectra. Whether it is related to the downward drift pattern observed in fast radio bursts (FRBs) is unclear. However, if the FRB down-drifting is due to this mechanism then it will be pronounced in those shocks that have isotropic kinetic energies ≳1044 erg. …

Radiation Effects On Space Solar Cells At Various Earth And Jupiter Orbital Altitudes, Naazneen Rana

Discovery Undergraduate Interdisciplinary Research Internship

Solar cells are used as the primary power source for earth-orbiting satellites and as a primary/secondary power source for various missions within the solar system. However, high energy particles from the sun, planetary magnetospheres, and the galaxy can affect the performance and life expectancy of the space solar cell and associated power systems. As the interests for interplanetary travel and the exploration of planets within our solar system increase, the need to understand a device’s performance within a particular planet’s environment is necessary. Therefore, this study will analyze the performance of space solar cells, particularly the SolAero IMM-α, at various …

A Search For Tev Gamma-Ray Emission From Pulsar Tails By Veritas, Mary P. Kertzman, Et Al.

Physics & Astronomy Faculty publications

We report on the search for very-high-energy gamma-ray emission from the regions around three nearby supersonic pulsars (PSR B0355+54, PSR J0357+3205, and PSR J1740+1000) that exhibit long X-ray tails. To date there is no clear detection of TeV emission from any pulsar tail that is prominent in X-ray or radio. We provide upper limits on the TeV flux, and luminosity, and also compare these limits with other pulsar wind nebulae detected in X-rays and the tail emission model predictions. We find that at least one of the three tails is likely to be detected in observations that are a factor …

12 C(E,E'Pn) Measurements Of Short Range Correlations In The Tensor-To-Scalar Interaction Transition Region, I. Korover, J. R. Pybus, A. Schmidt, F. Hauenstein, M. Duer, O. Hen, E. Piasetzky, L. B. Weinstein, D. W. Higinbotham, S. Adhikari, K. Adhikari, M. J. Amaryan, Giovanni Angelini, H. Atac, L. Barion, M. Battaglieri, A. Beck, I. Bedlinkskiy, Fatiha Benmokhtar, Steffen Strauch, Ralf W. Gothe, Krishna Chandra Neupane, Et. Al.

Faculty Publications

High-momentum configurations of nucleon pairs at short-distance are probed using measurements of the C-12(e, e' p) and C-12(e, e' pN) reactions (where N is either n or p), at high-Q(2) and x(B) > 1.1. The data span a missing-momentum range of 300-1000 MeV/c and are predominantly sensitive to the transition region of the strong nuclear interaction from a Tensor to Scalar interaction. The data are well reproduced by theoretical calculations using the Generalized Contact Formalism with both chiral and phenomenological nucleon-nucleon (NN) interaction models. This agreement suggests that the measured high missing-momentum protons up to 1000 MeV/c predominantly belong to short-ranged …

Ultra-High Speed Video Observations Of Intracloud Lightning Flash Initiation, Maribeth Stolzenburg, Thomas C. Marshall, Sampath Bandara, Brian Hurley, Raymond Siedlecki

Faculty and Student Publications

This study describes results from video observations of five intracloud flashes located ≤ 20 km from the camera and recorded with 6.1 µs exposure time and 6.66 µs frame intervals. Video data are supported with electric field change (E-change) and VHF measurements, with emphasis on the flash initiating event (IE) and initial breakdown (IB) stage. In four of the five flashes, the IE is accompanied by weak luminosity, ≤ 5% above background, lasting for 300–500 µs. Two of these four IEs were positive Narrow Bipolar Events (NBEs) with VHF powers of 43 and 990 W; these are the first (known) …

Search For The Decay Bs0 →Η′Η, N. K. Nisar, V. Savinov, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, H. Atmacan, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, P. Behera, J. Bennett, M. Bessner, V. Bhardwaj, B. Bhuyan, T. Bilka, J. Biswal, G. Bonvicini

Faculty and Student Publications

We report the results of the first search for the decay Bs0→η′η using 121.4 fb-1 of data collected at the I (5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e-collider. We observe no significant signal and set a 90% confidence-level upper limit of 6.5×10-5 on the branching fraction of this decay.

Toi-1634 B: An Ultra-Short-Period Keystone Planet Sitting Inside The M-Dwarf Radius Valley, R. Cloutier, D. Charbonneau, K. G. Stassun, F. Murgas, A. Mortier, R. Massey, J. J. Lissauer, D. W. Latham, J. Irwin, R. D. Haywood, P. Guerra, E. Girardin, S. A. Giacalone, P. Bosch-Cabot, A. Bieryla, J. Winn, C. A. Watson, R. Vanderspek, S. Udry, M. Tamura, A. Sozzetti, A. Shporer, D. Ségransan, S. Seager, A. B. Savel, D. Sasselov, M. Rose, G. Ricker, K. Rice, E. V. Quintana, S. N. Quinn, G. Piotto, D. Phillips, F. Pepe, M. Pedani, H. Parviainen, E. Palle, N. Narita, E. Molinari, G. Micela, S. Mcdermott, M. Mayor, R. A. Matson, A. F. Martinez Fiorenzano, C. Lovis, M. López-Morales, N. Kusakabe, Eric L.N. Jensen, J. M. Jenkins, C. X. Huang, S. B. Howell, A. Harutyunyan, G. Fűrész, A. Fukui, G. A. Esquerdo, E. Esparza-Borges, X. Dumusque, C. D. Dressing, L. Di Fabrizio, K. A. Collins, A. Collier Cameron, J. L. Christiansen, M. Cecconi, L. A. Buchhave, W. Boschin, G. Andreuzzi

Physics & Astronomy Faculty Works

Studies of close-in planets orbiting M dwarfs have suggested that the M-dwarf radius valley may be well explained by distinct formation timescales between enveloped terrestrials and rocky planets that form at late times in a gas-depleted environment. This scenario is at odds with the picture that close-in rocky planets form with a primordial gaseous envelope that is subsequently stripped away by some thermally driven mass-loss process. These two physical scenarios make unique predictions of the rocky/enveloped transition's dependence on orbital separation such that studying the compositions of planets within the M-dwarf radius valley may be able to establish the dominant …

Populating The Brown Dwarf And Stellar Boundary: Five Stars With Transiting Companions Near The Hydrogen-Burning Mass Limit, N. Grieves, F. Bouchy, M. Lendl, T. Carmichael, I. Mireles, A. Shporer, K. K. Mcleod, K. A. Collins, R. Brahm, K. G. Stassun, S. Gill, L. G. Bouma, T. Guillot, M. Cointepas, L. A. Dos Santos, S. L. Casewell, J. M. Jenkins, T. Henning, L. D. Nielsen, A. Psaridi, S. Udry, D. Ségransan, J. D. Eastman, G. Zhou, L. Abe, A. Agabi, G. Bakos, D. Charbonneau, K. I. Collins, K. D. Colon, N. Crouzet, G. Dransfield, P. Evans, R. F. Goeke, R. Hart, J. M. Irwin, Eric L.N. Jensen, A. Jordán, J. F. Kielkopf, D. W. Latham, W. Marie-Sainte, D. Mékarnia, P. Nelson, S. N. Quinn, D. J. Radford, D. R. Rodriguez, P. Rowden, F.–X. Schmider, R. P. Schwarz, J. C. Smith, C. Stockdale, O. Suarez, T.-G. Tan, A. H. M. J. Triaud, W. Waalkes, G. Wingham

Physics & Astronomy Faculty Works

We report the discovery of five transiting companions near the hydrogen-burning mass limit in close orbits around main sequence stars originally identified by the Transiting Exoplanet Survey Satellite (TESS) as TESS objects of interest (TOIs): TOI-148, TOI-587, TOI-681, TOI-746, and TOI-1213. Using TESS and ground-based photometry as well as radial velocities from the CORALIE, CHIRON, TRES, and FEROS spectrographs, we found the companions have orbital periods between 4.8 and 27.2 days, masses between 77 and 98 M_Jup, and radii between 0.81 and 1.66 R_Jup. These targets have masses near the uncertain lower limit of hydrogen core …

Space Resource Discussions Within The United Nations Committee On The Peaceful Uses Of Outer Space Legal Subcommittee: The Past, Present And Future, Anne Campbell

Institute for Earth and Space Exploration White Papers

The sixtieth session of the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) Legal Subcommittee occurred virtually between May 31^st, 2021 and June 11^th, 2021. The sixtieth session of the Legal Subcommittee included the highly anticipated scheduled informal consultations on “potential legal models for activities in exploration, exploitation and utilization of space resources” (United Nations Office of Outer Space Affairs, 2021f, p.2), which concluded with the establishment of a COPUOS Legal Subcommittee Working Group under a five-year workplan (United Nations Office of Outer Space Affairs, 2021f, p.33). The establishment of a Legal Subcommittee …

Discovery Of A Young Low-Mass Brown Dwarf Transiting A Fast-Rotating F-Type Star By The Galactic Plane Exoplanet (Gpx) Survey, P. Benni, A. Y. Burdanov, V. V. Krushinsky, A. Bonfanti, G. Hébrard, J. M. Almenara, S. Dalal, O. D. S. Demangeon, M. Tsantaki, J. Pepper, K. G. Stassun, A. Vanderburg, A. Belinski, F. Kashaev, K. Barkaoui, T. Kim, W. Kang, K. Antonyuk, V. V. Dyachenko, D. A. Tastegaev, A. Beskakotov, A. A. Mitrofanova, F. J. Pozuelos, E. D. Kuznetsov, A. Popov, F. Kieger, P. A. Wilson, G. Ricker, R. Vanderspek, D. W. Latham, S. Seager, J. M. Jenkins, E. Sokov, I. Sokova, A. Marchini, R. Papini, F. Salvaggio, M. Banfi, Ö. Baştürk, Ş. Torun, S. Yalçinkaya, K. Ivanov, G. Valyavin, E. Jehin, M. Gillon, E. Pakštienė, V.-P. Hentunen, S. Shadick, M. Bretton, A. Wünsche, J. Garlitz, Y. Jongen, D. Molina, E. Girardin, F. Grau Horta, R. Naves, Z. Benkhaldoun, M. D. Joner, M. Spencer, A. Bieryla, D. J. Stevens, Eric L.N. Jensen, K. A. Collins, D. Charbonneau, E. V. Quintana, S. E. Mullally, C. E. Henze

Physics & Astronomy Faculty Works

We announce the discovery of GPX-1 b, a transiting brown dwarf with a mass of 19.7 ± 1.6 M_Jup and a radius of 1.47 ± 0.10 R_Jup, the first substellar object discovered by the Galactic Plane eXoplanet (GPX) survey. The brown dwarf transits a moderately bright (V = 12.3 mag) fast-rotating F-type star with a projected rotational velocity v sin i_* 40 ± 10km s⁻¹. We use the isochrone placement algorithm to characterize the host star, which has effective temperature 7000 ± 200 K, mass 1.68 ± 0.10 M_⊙, radius 1.56 ± 0.10 …

Tic 454140642: A Compact, Coplanar, Quadruple-Lined Quadruple Star System Consisting Of Two Eclipsing Binaries, V. B. Kostov, B. P. Powell, G. Torres, T. Borkovits, S. A. Rappaport, A. Tokovinin, P. Zasche, D. Anderson, T. Barclay, P. Berlind, P. Brown, M. L. Calkins, K. A. Collins, K. I. Collins, D. M. Conti, G. A. Esquerdo, C. Hellier, Eric L.N. Jensen, J. Kamler, E. Kruse, D. W. Latham, M. Mašek, F. Murgas, G. Olmschenk, J. A. Orosz, A. Pál, E. Palle, R. P. Schwarz, C. Stockdale, D. Tamayo, R. Uhlař, W. F. Welsh, R. West

Physics & Astronomy Faculty Works

We report the discovery of a compact, coplanar, quadruple-lined, eclipsing quadruple star system from Transiting Exoplanet Survey Satellite data, TIC 454140642, also known as TYC 0074-01254-1. The target was first detected in Sector 5 with a 30-minute cadence in full-frame images and then observed in Sector 32 with a 2-minute cadence. The light curve exhibits two sets of primary and secondary eclipses with periods of P_A = 13.624 days (binary A) and P_B = 10.393 days (binary B). Analysis of archival and follow-up data shows clear eclipse-timing variations and divergent radial velocities, indicating dynamical interactions between the two …

Spatiotemporal Trends And Variability In The Centroid Of The Northern Hemisphere's Circumpolar Vortex, Nazla Bushra, Robert V. Rohli

Faculty Publications

Recent previous research has established the "sharpest gradient" approach to defining the circumpolar vortex and has identified correlations of the area and circularity of the Northern Hemisphere's circumpolar vortex (NHCPV) to important atmospheric-oceanic teleconnections. However, because geographical shifts in the NHCPV, independent of area or circularity changes, could affect surface environmental conditions, this research addresses the question of the extent to which the NHCPV centroid undergoes such shifts, both intra- and inter-annually. Results show that during the 1979-2017 period, the centroid has moved less on a daily basis in more recent years, perhaps indicative of a stabilization in circulation, with …

Toi-2076 And Toi-1807: Two Young, Comoving Planetary Systems Within 50 Pc Identified By Tess That Are Ideal Candidates For Further Follow Up, C. Hedges, A. Hughes, G. Zhou, T. J. David, J. Becker, S. Giacalone, A. Vanderburg, J. E. Rodriguez, A. Bieryla, C. Wirth, S. Atherton, T. Fetherolf, K. A. Collins, A. M. Price-Whelan, M. Bedell, S. N. Quinn, T. Gan, G. R. Ricker, D. W. Latham, R. K. Vanderspek, S. Seager, J. N. Winn, J. M. Jenkins, J. F. Kielkopf, R. P. Schwarz, C. D. Dressing, E. J. Gonzales, I. J. M. Crossfield, E. C. Matthews, Eric L.N. Jensen, E. Furlan, C. L. Gnilka, S. B. Howell, K. V. Lester, N. J. Scott, D. L. Feliz, M. B. Lund, R. J. Siverd, D. J. Stevens, N. Narita, A. Fukui, F. Murgas, E. Palle, P. J. Sutton, K. G. Stassun, L. G. Bouma, M. Vezie, J. N. Villaseñor, E. V. Quintana, J. C. Smith

Physics & Astronomy Faculty Works

We report the discovery of two planetary systems around comoving stars: TOI-2076 (TIC 27491137) and TOI-1807 (TIC 180695581). TOI-2076 is a nearby (41.9 pc) multiplanetary system orbiting a young (204 ± 50 Myr), bright (K = 7.115 in TIC v8.1) start. TOI-1807 hosts a single transiting planet and is similarly nearby (42.58 pc), similarly young (180 ± 40 Myr ), and bright. Both targets exhibit significant, periodic variability due to starspots, characteristic of their young ages. Using photometric data collected by TESS we identify three transiting planets around TOI-2076 with radii of R_b = 3.3 ± 0.04 R …

Transmission Telescope Optical Dynamic Alignment, Viviana Vladutescu, Aaron J. Swank, Dzu K. Le, Calvin R. Robinson, O. Scott Sands

Publications and Research

The Integrated Radio Optical Communication System (iROC) is designed to transmit data between Mars and Earth by means of radio waves at 32.67 GHz (Ka band) and laser beam (LB) at 1550 nm, both transmitted via a combined telescope/antenna called a teletenna. The iROC terminal will provide “beaconless” operations to allow full function from the outer planets. In order to point without the aid of an uplink beacon, the proof of concept presented here is addressing the need for an accurate determination and control of the relative position of the LB with respect to a reference star.

The experiment presented …

The Design, Creation, And Cognitive Evaluation Of Ranking Tasks In Introductory Astronomy, Emily A. Welch

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Ranking tasks are a type of interactive formative assessment. They allow students to explore a concept by ranking similar situations for a specified variable, preferably without computation of that variable. I created two sets of introductory astronomy ranking tasks: the first connects the Hertzsprung–Russell (HR) diagram and the Stephan-Boltzmann luminosity equation; the second uses the transit method (TM) to rank exoplanets by comparing the depth, duration, and frequency of transits.

These tasks are designed within the constructivist pedagogical framework. They require students to call upon their own relevant schema to establish an assessment rule by which to rank the tasks. …

Modeling The Spatiotemporal Dynamics Of Active Regions On The Sun Using Deep Neural Networks, Godwill Amankwa

Open Access Theses & Dissertations

Solar active regions are areas on the Sun's surface that have especially strong magnetic fields. Several phenomena that can have significant negative effects on technology and subsequently on human life, such as solar flares and coronal mass ejections (CMEs), are often associated with active regions.Since the physical phenomena underlying the evolution of active regions are still poorly understood, the accurate prediction of solar flares and coronal mass ejections remains an open problem.

Extracting insights from the available datasets of solar activity that can lead to a better understanding of solar active regions has been an important research goal at the …

Testing Galaxy Formation And Dark Matter With Low Surface Brightness Galaxies, Stacy S. Mcgaugh

Faculty Scholarship

Galaxies are the basic structural element of the universe; galaxy formation theory seeks to explain how these structures came to be. I trace some of the foundational ideas in galaxy formation, with emphasis on the need for non-baryonic cold dark matter. Many elements of early theory did not survive contact with observations of low surface brightness galaxies, leading to the need for auxiliary hypotheses like feedback. The failure points often trace to the surprising predictive successes of an alternative to dark matter, the Modified Newtonian Dynamics (MOND). While dark matter models are flexible in accommodating observations, they do not provide …

Nanoscale Assembly Of Dectin-1 And Its Glucan Ligand In Immunocyte Membranes And Pathogen Cell Walls, Akram Etemadi Amin

Physics & Astronomy ETDs

Candida spp. pathogens continue to be a significant health care burden with high mortality and exceeding enormous healthcare costs. Candida infection range varies from dermatological infection to more severe bloodstream infection in debilitated patients. Due to this, research dedicated to understanding biophysical interactions between Candida species and the host’s immune cells is essential. The C-type lectin’s (CtLs) are known to bind to Candida cell walls and play a crucial role in downstream immune signaling. It is known that β-glucans, the highly immunogenic polysaccharide in Candida’s cell wall, are mostly masked underneath a layer of mannosylated proteins. The amount of …

Detecting Optical Transients Using Artificial Neural Networks And Reference Images From Different Surveys, Katarzyna Wardęga, Adam Zadrozny, Martin Beroiz, Richard S. Camuccio, Mario C. Diaz

Physics & Astronomy Faculty Publications

We present a technique to detect optical transients based on an artificial neural networks method. We describe the architecture of two networks capable of comparing images of the same part of the sky taken by different telescopes. One image corresponds to the epoch in which a potential transient could exist; the other is a reference image of an earlier epoch. We use data obtained by the Dr. Cristina V. Torres Memorial Astronomical Observatory and archival reference images from the Sloan Digital Sky Survey. We trained a convolutional neural network and a dense layer network on simulated source samples and then …

Seasonal Variation Of Multiple-Muon Cosmic Ray Air Showers Observed In The Nova Detector Detector On The Surface, M. A. Acero, P. Adamson, L. Aliaga, N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, L. Asquith, A. Aurisano, A. Back, C. Backhouse, M. Baird, N. Balashov, P. Baldi, B. A. Bambah, S. Bashar, K. Bays, R. Bernstein, V. Bhatnagar, B. Bhuyan, J. Bian, Roberto Petti, Et. Al.

Faculty Publications

We report the rate of cosmic ray air showers with multiplicities exceeding 15 muon tracks recorded in the NOvA Far Detector between May 2016 and May 2018. The detector is located on the surface under an overburden of 3.6 meters water equivalent. We observe a seasonal dependence in the rate of multiple-muon showers, which varies in magnitude with multiplicity and zenith angle. During this period, the effective atmospheric temperature and surface pressure ranged between 210 K and 230 K and 940 mbar and 990 mbar, respectively; the shower rates are anticorrelated with the variation in the effective temperature. The variations …

Search For Anisotropic Gravitational-Wave Backgrounds Using Data From Advanced Ligo And Advanced Virgo's First Three Observing Runs, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang

Physics & Astronomy Faculty Publications

We report results from searches for anisotropic stochastic gravitational-wave backgrounds using data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. For the first time, we include Virgo data in our analysis and run our search with a new efficient pipeline called PyStoch on data folded over one sidereal day. We use gravitational-wave radiometry (broadband and narrow band) to produce sky maps of stochastic gravitational-wave backgrounds and to search for gravitational waves from point sources. A spherical harmonic decomposition method is employed to look for gravitationalwave emission from spatially-extended sources. Neither technique found evidence of …

Upper Limits On The Isotropic Gravitational-Wave Background From Advanced Ligo And Advanced Virgo's Third Observing Run, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang

Physics & Astronomy Faculty Publications

We report results of a search for an isotropic gravitational-wave background (GWB) using data from Advanced LIGO’s and Advanced Virgo’s third observing run (O3) combined with upper limits from the earlier O1 and O2 runs. Unlike in previous observing runs in the advanced detector era, we include Virgo in the search for the GWB. The results of the search are consistent with uncorrelated noise, and therefore we place upper limits on the strength of the GWB. We find that the dimensionless energy density ΩGW≤5.8×10−9 at the 95% credible level for a flat (frequency-independent) GWB, using a prior which is uniform …

A Mechanical Model For Magnetized Relativistic Blastwaves, Shunke Ai, Bing Zhang

Physics & Astronomy Faculty Research

The evolution of a relativistic blastwave is usually delineated under the assumption of pressure balance between forward- and reverse-shocked regions. However, such a treatment usually violates the energy conservation law, and is inconsistent with existing magnetohydrodynamic numerical simulation results. A mechanical model of non-magnetized blastwaves was proposed in previous work to solve the problem. In this paper, we generalize the mechanical model to the case of a blastwave driven by an ejecta with an arbitrary magnetization parameter $\sigma_{\rm ej}$. We test our modified mechanical model by considering a long-lasting magnetized ejecta and found that it is much better than the …

Hidden Treasures In The Unknown 3cr Extragalactic Radio Sky: A Multiwavelength Approach, V. Missaglia, F. Massaro, E. Liuzzo, A. Paggi, R. P. Kraft, W. R. Forman, A. Jimenez-Gallardo, Juan P. Madrid, F. Ricci, C. Stuardi

Physics & Astronomy Faculty Publications

We present the analysis of multiwavelength observations of seven extragalactic radio sources, listed as unidentified in the Third Cambridge Revised Catalog (3CR). X-ray observations, performed during Chandra Cycle 21, were compared to Very Large Array (VLA), Wide-field Infrared Survey Explorer, and Pan-STARRS observations in the radio, infrared, and optical bands, respectively. All sources in this sample lack a clear optical counterpart, and are thus missing their redshift and optical classification. In order to confirm the X-ray and infrared radio counterparts of core and extended components, here we present for the first time radio maps obtained manually reducing VLA archival data. …

Eccentricity Of Merging Neutron Star Binaries: Searches, Parameter Estimation, And Future Prospects, Amber Kiana Lenon

Dissertations - ALL

Since the start of the first observing run the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Advanced Virgo observatory have detected 48 binary black hole mergers and two binary neutron star mergers. Knowledge about the properties of the binary can be gained from the gravitational-wave observations. Binary neutron star systems can form with significant orbital eccentricity. Gravitational radiation efficiently removes this eccentricity from the binary's orbit as the star's inspiral together. This thesis describes a search for neutron star binaries that have an eccentric orbits when their gravitational waves enter the sensitive band of Advanced LIGO and Virgo. For …

Upper Limits On The Isotropic Gravitational-Wave Background From Advanced Ligo And Advanced Virgo's Third Observing Run, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, A. Adams, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, D. Agarwal, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, T. Akutsu, K. M. Aleman, Tiffany Summerscales

Faculty Publications

We report results of a search for an isotropic gravitational-wave background (GWB) using data from Advanced LIGO's and Advanced Virgo's third observing run (O3) combined with upper limits from the earlier O1 and O2 runs. Unlike in previous observing runs in the advanced detector era, we include Virgo in the search for the GWB. The results of the search are consistent with uncorrelated noise, and therefore we place upper limits on the strength of the GWB. We find that the dimensionless energy density ωGW≤5.8×10-9 at the 95% credible level for a flat (frequency-independent) GWB, using a prior which is uniform …