Gibbs Point Process Model For Young Star Clusters In M33,
2021
University of Toronto
Gibbs Point Process Model For Young Star Clusters In M33, Dayi Li, Pauline Barmby
Physics and Astronomy Publications
We demonstrate the power of Gibbs point process models from the spatial statistics literature when applied to studies of resolved galaxies. We conduct a rigorous analysis of the spatial distributions of objects in the star formation complexes of M33, including giant molecular clouds (GMCs) and young stellar cluster candidates (YSCCs). We choose a hierarchical model structure from GMCs to YSCCs based on the natural formation hierarchy between them. This approach circumvents the limitations of the empirical two-point correlation function analysis by naturally accounting for the inhomogeneity present in the distribution of YSCCs. We also investigate the effects of GMCs' properties …
Constraining The Nature Of The Pds 70 Protoplanets With Vlti/Gravity,
2021
California Institute of Technology
Constraining The Nature Of The Pds 70 Protoplanets With Vlti/Gravity, J. J. Wang, A. Vigan, S. Lacour, M. Nowak, T. Stolker, R. J. De Rosa, S. Ginzburg, P. Gao, R. Abuter, A. Amorim, R. Asensio-Torres, M. Bauböck, M. Benisty, J. P. Berger, H. Beust, J. L. Beuzit, S. Blunt, A. Boccaletti, A. Bohn, M. Bonnefoy, H. Bonnet, W. Brandner, F. Cantalloube, P. Caselli, B. Charnay, G. Chauvin, E. Choquet, V. Christiaens, Y. Clénet, V. Coudé Du Foresto, A. Cridland, P. T. De Zeeuw, K. Ward-Duong, Et Al
Astronomy: Faculty Publications
We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/ GRAVITY. We obtained K-band spectra and 100 μas precision astrometry of both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of 0.17 ± 0.06, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the …
Dynamical Modelling Of Cxogbs J175553.2-281633: A 10 H Long Orbital Period Cataclysmic Variable,
2021
Ctr Astrophys Harvard & Smithsonian, 60 Garden St, Cambridge, MA 02138 USA
Dynamical Modelling Of Cxogbs J175553.2-281633: A 10 H Long Orbital Period Cataclysmic Variable, Sebastian Gomez, Manuel A. P. Torres, Peter G. Jonker, Zuzanna Kostrzewa-Rutkowska, Theo F. J. Van Grunsven, Andrzej Udalski, Robert I. Hynes, Craig O. Heinke, Thomas J. Maccarone, Ricardo Salinas, Jay Strader
Faculty Publications
We present modelling of the long-term optical light and radial velocity curves of the binary stellar system CXOGBS J175553.2-281633, first detected in X-rays in the Chandra Galactic Bulge Survey. We analysed 7 yr of optical I-band photometry from Optical Gravitational Lensing Experiment and found long-term variations from year to year. These long-term variations can most likely be explained with by either variations in the luminosity of the accretion disc or a spotted secondary star. The phased light curve has a sinusoidal shape, which we interpret as being due to ellipsoidal modulations. We improve the orbital period to be P = …
Planet Hunters Tess Ii: Findings From The First Two Years Of Tess,
2021
Univ Oxford, Dept Phys, Keble Rd, Oxford OX1 3RH, England
Planet Hunters Tess Ii: Findings From The First Two Years Of Tess, N. L. Eisner, O. Barragan, C. Lintott, S. Aigrain, B. Nicholson, T. S. Boyajian, S. Howell, C. Johnston, B. Lakeland, G. Miller, A. Mcmaster, H. Parviainen, E. J. Safron, M. E. Schwamb, L. Trouille, S. Vaughan, N. Zicher, C. Allen, S. Allen, M. Bouslog, C. Johnson, M. N. Simon, Z. Wolfenbarger, E. M. L. Baeten, D. M. Bundy, T. Hoffman
Faculty Publications
We present the results from the first two years of the Planet Hunters TESS (PHT) citizen science project, which identifies planet candidates in the TESS (Transiting Exoplanet Survey Satellite) data by engaging members of the general public. Over 22000 citizen scientists from around the world visually inspected the first 26 sectors of TESS data in order to help identify transit-like signals. We use a clustering algorithm to combine these classifications into a ranked list of events for each sector, the top 500 of which are then visually vetted by the science team. We assess the detection efficiency of this methodology …
Studying The Conditions For Magnetic Reconnection In Solar Flares With And Without Precursor Flares,
2021
Air Force Institute of Technology
Studying The Conditions For Magnetic Reconnection In Solar Flares With And Without Precursor Flares, Seth H. Garland
Theses and Dissertations
Forecasting of solar flares remains a challenge due to the limited understanding of the triggering mechanisms associated with magnetic reconnection, the primary physical phenomenon connected to these events. Consequently, methods continue to rely on the climatology of solar flare events as opposed to the underlying physics principles. Models of magnetic reconnection in the solar atmosphere places the null point of the reconnection within the corona. Though as of now the coronal magnetic field cannot be directly measured, the field is tied to the photospheric magnetic field, which can be. This study utilized data from the Solar Dynamics Observatory Helioseismic and …
How And Why Mars Lost Its Water,
2021
College of DuPage
How And Why Mars Lost Its Water, Sana Akhter, Andre Beikircher
2021 Honors Council of the Illinois Region
The topic of this paper is to investigate how and why Mars lost its water. It is important to study the loss of water on Mars because it can give us a better understanding of how Mars once looked, if life were possible, and how it could have changed so drastically to what it is now. The paper aims to address which factors led to Mars losing its water and how long ago this happened. Using our data, we will predict how quickly Mars’ core cooled, when its magnetic field weakened, and when the water was lost. We learned that …
Quasinormal Modes And Their Overtones At The Common Horizon In A Binary Black Hole Merger,
2021
Max Planck Inst Gravitat Phys, Albert Einstein Inst, Callinstr 38, D-30167 Hannover, Germany, Leibniz Univ Hannover, D-30167 Hannover, Germany
Quasinormal Modes And Their Overtones At The Common Horizon In A Binary Black Hole Merger, Pierre Mourier, Xisco Jimenez Forteza, Daniel Pook-Kolb, Dadri Krishnan, Erik Schnetter
Faculty Publications
It is expected that all astrophysical black holes in equilibrium are well described by the Kerr solution. Moreover, any black hole far away from equilibrium, such as one initially formed in a compact binary merger or by the collapse of a massive star, will eventually reach a final equilibrium Kerr state. At sufficiently late times in this process of reaching equilibrium, we expect that the black hole is modeled as a perturbation around the final state. The emitted gravitational waves will then be damped sinusoids with frequencies and damping times given by the quasinormal mode spectrum of the final Kerr …
Differential Cross Sections For Λ(1520) Using Photoproduction At Clas,
2021
University of South Carolina
Differential Cross Sections For Λ(1520) Using Photoproduction At Clas, U. Shrestha, T. Chetry, C. Djalali, K. Hicks, S. I. Nam, K. P. Adhikari, M. Amaryan, G. Angelini, H. Atac, L. Barion, M. Battaglieri, I. Bedlinskiy, F. Benmokhtar, A. Bianconi, A. S. Biselli, M. Bondi, F. Bossú, S. Boiarinov, W. J. Briscoe, W. K. Brooks, Steffen Strauch, Et. Al.
Faculty Publications
The reaction 𝛾𝑝→𝐾+Λ(1520) using photoproduction data from the CLAS 𝑔12 experiment at Jefferson Lab is studied. The decay of Λ(1520) into two exclusive channels, Σ+𝜋− and Σ−𝜋+, is studied from the detected 𝐾+, 𝜋+, and 𝜋− particles. A good agreement is established for the Λ(1520) differential cross sections with the previous CLAS measurements. The differential cross sections as a function of center-of-mass angle are extended to higher photon energies. Newly added are the differential cross sections as a function of invariant four-momentum transfer 𝑡, which is the natural variable to use for a theoretical model based on a Regge-exchange reaction …
The Pencil Code, A Modular Mpi Code For Partial Differential Equations And Particles: Multipurpose And Multiuser-Maintained,
2021
University of Nevada, Las Vegas
The Pencil Code, A Modular Mpi Code For Partial Differential Equations And Particles: Multipurpose And Multiuser-Maintained, The Pencil Code Collaboration, Chao-Chin Yang
Physics & Astronomy Faculty Research
The Pencil Code is a highly modular physics-oriented simulation code that can be adapted to a wide range of applications. It is primarily designed to solve partial differential equations (PDEs) of compressible hydrodynamics and has lots of add-ons ranging from astrophysical magnetohydrodynamics (MHD) (A. Brandenburg & Dobler, 2010) to meteorological cloud microphysics (Li et al., 2017) and engineering applications in combustion (Babkovskaia et al., 2011). Nevertheless, the framework is general and can also be applied to situations not related to hydrodynamics or even PDEs, for example when just the message passing interface or input/output strategies of the code are to …
Dft Study Of “Unlayered Graphene Solid” Formation, In Liquid Carbon Droplets At Low Pressures,
2021
University of Missouri-St. Louis
Dft Study Of “Unlayered Graphene Solid” Formation, In Liquid Carbon Droplets At Low Pressures, Chathuri Silva, Philip Chrostoski, Phil Fraundorf
Physics Faculty Works
This atomistic modeling study is companion to new experimental work on carbon vapor slow-cooled in (a) the laboratory and (b) the atmosphere of ancient carbon-synthesizing stars. It specifically follows up on TEM clues about the nucleation of unlayered graphene sheets in a solidifying carbon liquid, to show that 5 atom loops may help explain evidence for faceted pentacones in a slow-cooled melt. This is also first in a series of modeling studies that may open the door to laboratory studies of (i) condensation in cool-giant star atmospheres and (ii) liquid carbon at low pressures.
The Pedagogical Representation Of Mass Functions With Lego And Their Origin,
2021
Nova Southeastern University
The Pedagogical Representation Of Mass Functions With Lego And Their Origin, Stefan Kautsch
Chemistry and Physics Faculty Articles
We promote the teaching of mass functions as an integral part of an interdisciplinary science education. Mass functions characterize the frequency distributions of objects with different masses on all cosmic scales. We intend to enhance experiential learning of this concept with a creative LEGO brick experiment for a diverse student audience. To our surprise, the LEGO mass function is not only qualitatively but also quantitatively comparable to mass functions found across the universe. We also discuss the relation between gravitation and mass distributions as a possible explanation for the continuity of the universal mass function.
A Cautionary Tale In Fitting Galaxy Rotation Curves With Bayesian Techniques: Does Newton's Constant Vary From Galaxy To Galaxy?,
2021
Case Western Reserve University
A Cautionary Tale In Fitting Galaxy Rotation Curves With Bayesian Techniques: Does Newton's Constant Vary From Galaxy To Galaxy?, Pengfei Li, Stacy Mcgaugh
Faculty Scholarship
The application of Bayesian techniques to astronomical data is generally non-trivial because the fitting parameters can be strongly degenerated and the formal uncertainties are themselves uncertain. An example is provided by the contradictory claims over the presence or absence of a universal acceleration scale (g†) in galaxies based on Bayesian fits to rotation curves. To illustrate this we present an analysis in which the Newtonian gravitational constant GN is allowed to vary from galaxy to galaxy when fitting rotation curves from the SPARC database, in analogy to g† in the recently debated Bayesian analyses. When imposing flat priors on GN, …
Speckle Imaging Characterization Of Radial Velocity Exoplanet Systems,
2021
University of California, Riverside
Speckle Imaging Characterization Of Radial Velocity Exoplanet Systems, Paul A. Dalba, Stephen R. Kane, Steve B. Howell, Elliott P. Horch, Zhexing Li, Lea A. Hirsch, Jennifer Burt, Timothy D. Brandt, Teo Močnik, Gregory W. Henry, Mark E. Everett, Lee J. Rosenthal, Andrew W. Howard
Information Systems and Engineering Management Research Publications
We conducted speckle imaging observations of 53 stellar systems that were members of long-term radial velocity (RV) monitoring campaigns and exhibited substantial accelerations indicative of planetary or stellar companions in wide orbits. Our observations were made with blue and red filters using the Differential Speckle Survey Instrument at Gemini-South and the NN-Explore Exoplanet Stellar Speckle Imager at the WIYN telescope. The speckle imaging identifies eight luminous companions within 2'' of the primary stars. In three of these systems—HD 1388, HD 87359, and HD 104304—the properties of the imaged companion are consistent with the RV measurements, suggesting that these companions may …
Constraining Protoplanetary Disc Accretion And Young Planets Using Alma Kinematic Observations,
2021
University of Nevada, Las Vegas
Constraining Protoplanetary Disc Accretion And Young Planets Using Alma Kinematic Observations, Ian Rabago, Zhaohuan Zhu
Physics & Astronomy Faculty Research
Recent ALMA molecular line observations have revealed 3D gas velocity structure in protoplanetary discs, shedding light on mechanisms of disc accretion and structure formation. (1) By carrying out viscous simulations, we confirm that the disc's velocity structure differs dramatically using vertical stress profiles from different accretion mechanisms. Thus, kinematic observations tracing flows at different disc heights can potentially distinguish different accretion mechanisms. On the other hand, the disc surface density evolution is mostly determined by the vertically integrated stress. The sharp disc outer edge constrained by recent kinematic observations can be caused by a radially varying alpha in the disc. …
Turbulent Gas In Lensed Planck-Selected Starbursts At Z ∼ 1-3.5,
2021
Universität Bonn
Turbulent Gas In Lensed Planck-Selected Starbursts At Z ∼ 1-3.5, Kevin C. Harrington, Axel Weiss, Min S. Yun, Benjamin Magnelli, C. E. Sharon, T. K.D. Leung, A. Vishwas, Q. D. Wang, D. T. Frayer, E. F. Jiménez-Andrade, D. Liu, P. García, E. Romano-Díaz, B. L. Frye, S. Jarugula, T. Bǎdescu, D. Berman, H. Dannerbauer, A. Díaz-Sánchez, L. Grassitelli, P. Kamieneski, W. J. Kim, A. Kirkpatrick, J. D. Lowenthal, H. Messias, J. Puschnig, G. J. Stacey, P. Torne, F. Bertoldi
Astronomy: Faculty Publications
Dusty star-forming galaxies at high redshift (1 < z < 3) represent the most intense star-forming regions in the universe. Key aspects to these processes are the gas heating and cooling mechanisms, and although it is well known that these galaxies are gas-rich, little is known about the gas excitation conditions. Only a few detailed radiative transfer studies have been carried out owing to a lack of multiple line detections per galaxy. Here we examine these processes in a sample of 24 strongly lensed star-forming galaxies identified by the Planck satellite (LPs) at z ∼ 1.1-3.5. We analyze 162 CO rotational transitions (ranging from J up = 1 to 12) and 37 atomic carbon fine-structure lines ([C i]) in order to characterize the physical conditions of the gas in the sample of LPs. We simultaneously fit the CO and [C i] lines and the dust continuum emission, using two different non-LTE, radiative transfer models. The first model represents a two-component gas density, while the second assumes a turbulence-driven lognormal gas density distribution. These LPs are among the most gas-rich, IR-luminous galaxies ever observed (μL L IR(8-1000 μm) ∼ 1013-14.6 L⊙; «μLMISM» = (2.7 ± 1.2) × 1012 Mo˙ with μL ∼ 10-30 the average lens magnification factor). Our results suggest that the turbulent interstellar medium present in the LPs can be well characterized by a high turbulent velocity dispersion («ΔVturb» ∼ 100 km s-1) and ratios of gas kinetic temperature to dust temperature «T kin/T d» ∼ 2.5, sustained on scales larger than a few kiloparsecs. We speculate that the average surface density of the molecular gas mass and IR luminosity, Σ ∼ 103-4 M o˙ pc-2 and Σ ∼ 1011-12 L o˙ kpc-2, arise from both stellar mechanical feedback and a steady momentum injection from the accretion of intergalactic gas.
Measurement Of Time-Dependent Cp Violation Parameters In B0 → Ks0 Ks0 Ks0 Decays At Belle,
2021
Kyungpook National University
Measurement Of Time-Dependent Cp Violation Parameters In B0 → Ks0 Ks0 Ks0 Decays At Belle, K. H. Kang, H. Park, T. Higuchi, K. Miyabayashi, K. Sumisawa, I. Adachi, J. K. Ahn, H. Aihara, S. Al Said, D. M. Asner, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, A. M. Bakich, P. Behera, C. Beleño, J. Bennett
Faculty and Student Publications
We measure the time-dependent CP violation parameters in B0→KS0KS0KS0 decays using 772×106BB¯ pairs collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. The obtained mixing-induced and direct CP asymmetries are -0.71±0.23 (stat)±0.05 (syst) and 0.12±0.16 (stat)±0.05 (syst), respectively. These values are consistent with the Standard Model predictions. The significance of CP violation differs from zero by 2.5 standard deviations.
Non-Diffracting States At Exceptional Points,
2021
The University of Texas Rio Grande Valley
Non-Diffracting States At Exceptional Points, Cem Yuce, Hamidreza Ramezani
Physics & Astronomy Faculty Publications
We propose to use exceptional points (EPs) to construct diffraction-free beam propagation and localized power oscillation in lattices. We specifically consider two systems to utilize EPs for diffraction-free beam propagation, one in synthetic gauge lattices and the other one, in unidirectionally coupled resonators where each resonator individually is capable of creating orbital angular momentum beams (OAM). In the second system, we introduce the concept of robust and tunable OAM beam propagation in discrete lattices. We show that one can create robust OAM beams in an arbitrary number of sites of a photonic lattice. Furthermore, we report power oscillation at the …
Extending The Frequency Reach Of Pulsar Timing Array Based Gravitational Wave Search Without High Cadence Observations,
2021
The University of Texas Rio Grande Valley
Extending The Frequency Reach Of Pulsar Timing Array Based Gravitational Wave Search Without High Cadence Observations, Yan Wang, Soumya Mohanty, Zhoujian Cao
Physics & Astronomy Faculty Publications
Gravitational wave (GW) searches using pulsar timing arrays (PTAs) are assumed to be limited by the typical average observational cadence of 1/(2 weeks) for a single pulsar to GW frequencies . 4 × 10−7 Hz. We show that this assumption is incorrect and that a PTA can detect signals with much higher frequencies, which are preserved in the data due to aliasing, by exploiting asynchronous observations from multiple pulsars. This allows an observation strategy that is scalable to future large-scale PTAs containing O(103) pulsars, enabled by the Five-hundred meter Aperture Spherical Telescope and the Square Kilometer Array, without requiring a …
Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites,
2021
The University of Texas Rio Grande Valley
Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites, Farnaz Safi Samghabadi, Long Chang, Mohammad Khodadadi, Karen S. Martirosyan, Dmitri Litvinov
Physics & Astronomy Faculty Publications
Cobalt ferrite (CoFe2O4)/barium titanate (BaTiO3) particulate composites exhibiting high magnetoelectric coefficients were synthesized from low-cost commercial precursors using mechanical ball milling followed by high-temperature annealing. CoFe2O4 (20 nm–50 nm) and either cubic or tetragonal BaTiO3 nanoparticle powders were used for the synthesis. It was found that utilizing a 50nm cubic BaTiO3 powder as a precursor results in a composite with a magnetoelectric coupling coefficient value as high as 4.3 mV/Oe cm, which is comparable to those of chemically synthesized core–shell CoFe2O4–BaTiO3 nanoparticles. The microstructure of these composites is dramatically different from the composite synthesized using 200nm tetragonal BaTiO3 powder. CoFe2O4 …
Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites,
2021
The University of Texas Rio Grande Valley
Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites, Farnaz Safi Samghabadi, Long Chang, Mohammad Khodadadi, Karen S. Martirosyan, Dmitri Litvinov
Physics & Astronomy Faculty Publications
Cobalt ferrite (CoFe2O4)/barium titanate (BaTiO3) particulate composites exhibiting high magnetoelectric coefficients were synthesized from low-cost commercial precursors using mechanical ball milling followed by high-temperature annealing. CoFe2O4 (20 nm–50 nm) and either cubic or tetragonal BaTiO3 nanoparticle powders were used for the synthesis. It was found that utilizing a 50nm cubic BaTiO3 powder as a precursor results in a composite with a magnetoelectric coupling coefficient value as high as 4.3 mV/Oe cm, which is comparable to those of chemically synthesized core–shell CoFe2O4–BaTiO3 nanoparticles. The microstructure of these composites is dramatically different from the composite synthesized using 200nm tetragonal BaTiO3 powder. CoFe2O4 …
