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6,126 full-text articles. Page 2 of 184.

Multicolor Blackbody Emission In Grb 081221, Shu-Jin Hou, Bin-Bin Zhang, Yan-Zhi Meng, Xue-Feng Wu, En-Wei Liang, Hou-Jun Lü, Tong Liu, Yun-Feng Liang, Lin Lin, Rui-jing Lu, Jin-Shu Huang, Bing Zhang 2018 Nanyang Normal University; Chinese Academy of Sciences; Guangxi University

Multicolor Blackbody Emission In Grb 081221, Shu-Jin Hou, Bin-Bin Zhang, Yan-Zhi Meng, Xue-Feng Wu, En-Wei Liang, Hou-Jun Lü, Tong Liu, Yun-Feng Liang, Lin Lin, Rui-Jing Lu, Jin-Shu Huang, Bing Zhang

Physics & Astronomy Faculty Publications

The radiation mechanism of the prompt emission of gamma-ray bursts (GRBs) remains an open question. Although their spectra are usually well fitted with the empirical Band function, which is widely believed to be fully nonthermal and interpreted as an optically thin synchrotron emission, accumulating evidence shows that a thermal component actually exists. In this paper, a multicolor blackbody (mBB) model is proposed for the time-integrated spectrum of GRB 081221 by assuming a power-law distribution of the thermal luminosities with temperature, which manifests photospheric emissions from a different radius and/or angle. The effects of the minimum temperature kT min, the ...


A Comprehensive Analysis Of Fermi Gamma-Ray Burst Data. Iv. Spectral Lag And Its Relation To E P Evolution, Rui-Jing Lu, Yun-Feng Liang, Da-Bin Lin, Jing Lü, Xiang-Gao Wang, Hou-Jun Lü, Hong-Bang Liu, En-Wei Liang, Bing Zhang 2018 Guangxi University

A Comprehensive Analysis Of Fermi Gamma-Ray Burst Data. Iv. Spectral Lag And Its Relation To E P Evolution, Rui-Jing Lu, Yun-Feng Liang, Da-Bin Lin, Jing Lü, Xiang-Gao Wang, Hou-Jun Lü, Hong-Bang Liu, En-Wei Liang, Bing Zhang

Physics & Astronomy Faculty Publications

The spectral evolution and spectral lag behavior of 92 bright pulses from 84 gamma-ray bursts observed by the Fermi Gamma-ray Burst Monitor (GBM) telescope are studied. These pulses can be classified into hard-to-soft pulses (H2S; 64/92), H2S-dominated-tracking pulses (21/92), and other tracking pulses (7/92). We focus on the relationship between spectral evolution and spectral lags of H2S and H2S-dominated-tracking pulses. The main trend of spectral evolution (lag behavior) is estimated with ( ), where E p is the peak photon energy in the radiation spectrum, t + t 0 is the observer time relative to the beginning of pulse −t ...


Chromodynamical Analysis Of Lenticular Galaxies Using Globular Clusters And Planetary Nebulae, Emilio Zanatta, Arianna Cortesi, Ana Chies-Santos, Duncan Forbes, Aaron Romanowsky, Adebusola Alabi, Lodovico Coccato, Claudia Mendes de Oliveira, Jean Brodie, Michael Merrifield 2018 Universidade Federal do Rio Grande do Sul

Chromodynamical Analysis Of Lenticular Galaxies Using Globular Clusters And Planetary Nebulae, Emilio Zanatta, Arianna Cortesi, Ana Chies-Santos, Duncan Forbes, Aaron Romanowsky, Adebusola Alabi, Lodovico Coccato, Claudia Mendes De Oliveira, Jean Brodie, Michael Merrifield

Faculty Publications

Recovering the origins of lenticular galaxies can shed light on the understanding of galaxy and compare them with the kinematics of planetary nebulae (PNe). The PNe and GC data come from the Planetary Nebulae Spectrograph and the SLUGGS Surveys. Through photometric spheroid-disc decomposition and PNe kinematics. we find the probability for a given GC to belong to either the spheroid or the disc of its host galaxy or be rejected from the model. We find that there is no correlation between the components that the GCs are likely to belong to and their colours. Particularly, for NGC 2768, we find ...


The Optical/Nir Afterglow Of Grb 111209a: Complex Yet Not Unprecedented, D. A. Kann, P. Schady, E. F. Olivares, S. Klose, A. Rossi, D. A. Perley, Bing Zhang, T. Krühler, J. Greiner, A. Nicuesa Guelbenzu, J. Elliott, F. Knust, Z. Cano, R. Filgas, E. Pian, P. Mazzali, J. P. U. Fynbo, G. Leloudas, P. M. J. Afonso, C. Delvaux, J. F. Graham, A. Rau, S. Schmidl, S. Schulze, M. Tanga, A. C. Updike, K. Varela 2018 Thüringer Landessternwarte Tautenburg; Max-Planck-Institut für extraterrestrische Physik; Technische Universität München; Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n

The Optical/Nir Afterglow Of Grb 111209a: Complex Yet Not Unprecedented, D. A. Kann, P. Schady, E. F. Olivares, S. Klose, A. Rossi, D. A. Perley, Bing Zhang, T. Krühler, J. Greiner, A. Nicuesa Guelbenzu, J. Elliott, F. Knust, Z. Cano, R. Filgas, E. Pian, P. Mazzali, J. P. U. Fynbo, G. Leloudas, P. M. J. Afonso, C. Delvaux, J. F. Graham, A. Rau, S. Schmidl, S. Schulze, M. Tanga, A. C. Updike, K. Varela

Physics & Astronomy Faculty Publications

Context. Afterglows of gamma-ray bursts (GRBs) are simple in the most basic model, but can show many complex features. The ultra-long duration GRB 111209A, one of the longest GRBs ever detected, also has the best-monitored afterglow in this rare class of GRBs. Aims. We want to address the question whether GRB 111209A was a special event beyond its extreme duration alone, and whether it is a classical GRB or another kind of high-energy transient. The afterglow may yield significant clues. Methods. We present afterglow photometry obtained in seven bands with the GROND imager as well as in further seven bands ...


Event Engineering Studies For Heavy Flavor Production And Hadronization In High Multiplicity Hadron-Hadron And Hadron-Nucleus Collisions, Yan-Qing Ma, Prithwish Tribedy, Raju Venugopalan, Kazuhiro Watanabe 2018 Old Dominion University

Event Engineering Studies For Heavy Flavor Production And Hadronization In High Multiplicity Hadron-Hadron And Hadron-Nucleus Collisions, Yan-Qing Ma, Prithwish Tribedy, Raju Venugopalan, Kazuhiro Watanabe

Physics Faculty Publications

Heavy flavor measurements in high multiplicity proton-proton and proton-nucleus collisions at collider energies enable unique insights into their production and hadronization mechanism because experimental and theoretical uncertainties cancel in ratios of their cross sections relative to minimum bias events. We explore such event engineering using the color glass condensate (CGC) effective field theory to compute short-distance charmonium cross sections. The CGC is combined with heavy-quark fragmentation functions to compute D-meson cross sections; for the J/ψ, hadronization is described employing nonrelativistic QCD (NRQCD) and an improved color evaporation model. Excellent agreement is found between the CGC computations and the LHC ...


Chromodynamical Analysis Of Lenticular Galaxies Using Globular Clusters And Planetary Nebulae, Emilio J B Zanatta, Arianna Cortesi, Ana L. Chies-Santos, Duncan A. Forbes, Aaron J. Romanowsky, Adebusola B. Alabi, Lodovico Coccato, Claudia Mendes de Oliveira, Jean P. Brodie, Michael M. Merrifield 2018 Universidade Federal do Rio Grande do Sul

Chromodynamical Analysis Of Lenticular Galaxies Using Globular Clusters And Planetary Nebulae, Emilio J B Zanatta, Arianna Cortesi, Ana L. Chies-Santos, Duncan A. Forbes, Aaron J. Romanowsky, Adebusola B. Alabi, Lodovico Coccato, Claudia Mendes De Oliveira, Jean P. Brodie, Michael M. Merrifield

Aaron J. Romanowsky

Recovering the origins of lenticular galaxies can shed light on the understanding of galaxy and compare them with the kinematics of planetary nebulae (PNe). The PNe and GC data come from the Planetary Nebulae Spectrograph and the SLUGGS Surveys. Through photometric spheroid-disc decomposition and PNe kinematics. we find the probability for a given GC to belong to either the spheroid or the disc of its host galaxy or be rejected from the model. We find that there is no correlation between the components that the GCs are likely to belong to and their colours. Particularly, for NGC 2768, we find ...


Long-Lived Remnants From Binary Neutron Star Mergers, David Radice, Albino Perego, Sebastiano Bernuzzi, Bing Zhang 2018 Princeton University

Long-Lived Remnants From Binary Neutron Star Mergers, David Radice, Albino Perego, Sebastiano Bernuzzi, Bing Zhang

Physics & Astronomy Faculty Publications

Massive neutron stars (NSs) with lifetimes of at least several seconds are expected to be the result of a sizable fraction of NS mergers. We study their formation using a large set of numerical relativity simulations. We show that they are initially endowed with angular momentum that significantly exceeds the mass-shedding limit for rigidly rotating equilibria. We find that gravitational wave (GW) emission is not able to remove this excess angular momentum within the time over which solid body rotation should be achieved. Instead, we argue that the excess angular momentum could be carried away by massive winds. Long-lived merger ...


Database Review: Sao/Nasa Astrophysics Data System, Laura Pope Robbins 2018 Embry-Riddle Aeronautical University

Database Review: Sao/Nasa Astrophysics Data System, Laura Pope Robbins

Publications

Laura Pope Robbins is an advisor for The Charleston Advisor, and the review below is included in Scholarly Commons with the permission of the publisher.

The Astrophysics Data System (ADS) is the premier Open Access research database for astronomy and astrophysics containing over 13 million bibliographic records. These records include journal articles, books, conference proceedings, historical observatory bulletins, and other gray literature. An exceptional feature of ADS is the visualizations it creates, showing author networks, overlapping citations, and frequently occurring terminology giving researchers new ways to explore the literature. It is a unique resource that is as easy for a ...


Origins Of Ultradiffuse Galaxies In The Coma Cluster – I. Constraints From Velocity Phase Space, Adebusola Alabi, Anna Ferré-Mateu, Aaron Romanowsky, Jean Brodie, Duncan Forbes, Asher Wasserman, Sabine Bellstedt, Ignacio Martín-Navarro, Viraj Pandya, Maria Stone, Nobuhiro Okabe 2018 University of California Observatories

Origins Of Ultradiffuse Galaxies In The Coma Cluster – I. Constraints From Velocity Phase Space, Adebusola Alabi, Anna Ferré-Mateu, Aaron Romanowsky, Jean Brodie, Duncan Forbes, Asher Wasserman, Sabine Bellstedt, Ignacio Martín-Navarro, Viraj Pandya, Maria Stone, Nobuhiro Okabe

Faculty Publications

We use Keck/DEIMOS spectroscopy to confirm the cluster membership of 16 ultradiffuse galaxies (UDGs) in the Coma cluster, bringing the total number of spectroscopically confirmed UDGs from the Yagi et al. (Y16) catalogue to 25. We also identify a new cluster background UDG, confirming that most (∼95 per cent) of the UDGs in the Y16 catalogue belong to the Coma cluster. In this pilot study of Coma UDGs in velocity phase space, we find evidence of a diverse origin for Coma cluster UDGs, similar to normal dwarf galaxies. Some UDGs in our sample are consistent with being late infalls ...


Polynomial Fitting, R. Steven Turley 2018 Brigham Young University

Polynomial Fitting, R. Steven Turley

All Faculty Publications

This article reviews the theory and some good practice for fitting polynomials to data. I show by theory and example why fitting using a basis of orthogonal polynomials rather than monomials is desirable. I also show how to scale the independent variable for a more stable fit. I also demonstrate how to compute the uncertainty in the fit parameters. Finally, I discuss regression analysis: how to determine whether adding an additional term to the fit is justified.


Fitting Parameter Uncertainties In Least Squares Fitting, R. Steven Turley 2018 Brigham Young University

Fitting Parameter Uncertainties In Least Squares Fitting, R. Steven Turley

All Faculty Publications

This article review the theory and practice of computing uncertainties in the fit parameters in least squares fits. It shows how to estimate the uncertainties and gives some numerical examples in Julia of their use. Examples are given and validated for both linear and nonlinear fits.


Photoproduction Of K+ K- Meson Pairs On The Proton, S. Lombardo, M. Battaglieri, A. Celentano, A. D'Angelo, R. De Vita, A. Filippi, D. I. Glazier, M. Khachatryan, A. Klein, Y. Prok, The CLAS Collaboration 2018 Old Dominion University

Photoproduction Of K+ K- Meson Pairs On The Proton, S. Lombardo, M. Battaglieri, A. Celentano, A. D'Angelo, R. De Vita, A. Filippi, D. I. Glazier, M. Khachatryan, A. Klein, Y. Prok, The Clas Collaboration

Physics Faculty Publications

The exclusive reaction γp → pK+K was studied in the photon energy range 3.0–3.8 GeV and momentum transfer range 0.6 < −t< 1.3 GeV2. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range the integrated luminosity was approximately 20 pb−1. The reaction was isolated by detecting the K+ and the proton in CLAS, and reconstructing the K via the missing-mass technique. Moments of the dikaon decay angular distributions were extracted from the experimental data. Besides the dominant contribution of the ϕ meson in the P wave, evidence for S ...


From Thermal Dissociation To Condensation In The Atmospheres Of Ultra Hot Jupiters: Wasp-121b In Context, Vivien Parmentier, Mike R. Line, Jacob L. Bean, Megan Mansfield, Laura Kreidberg, Roxana Lupu, Channon Visscher, Jean-Michel Desert, Jonathan J. Fortney, Magalie Deleuil, Jacob Arcangeli, Adam P. Showman, Mark S. Marley 2018 University of Oxford

From Thermal Dissociation To Condensation In The Atmospheres Of Ultra Hot Jupiters: Wasp-121b In Context, Vivien Parmentier, Mike R. Line, Jacob L. Bean, Megan Mansfield, Laura Kreidberg, Roxana Lupu, Channon Visscher, Jean-Michel Desert, Jonathan J. Fortney, Magalie Deleuil, Jacob Arcangeli, Adam P. Showman, Mark S. Marley

Faculty Work Comprehensive List

Context. A new class of exoplanets has emerged: the ultra hot Jupiters, the hottest close-in gas giants. The majority of them have weaker-than-expected spectral features in the 1.1−1.7 μm bandpass probed by HST/WFC3 but stronger spectral features at longer wavelengths probed by Spitzer. This led previous authors to puzzling conclusions about the thermal structures and chemical abundances of these planets.

Aims. We investigate how thermal dissociation, ionization, H− opacity, and clouds shape the thermal structures and spectral properties of ultra hot Jupiters.

Methods. We use the SPARC/MITgcm to model the atmospheres of four ultra ...


Origins Of Ultradiffuse Galaxies In The Coma Cluster – I. Constraints From Velocity Phase Space, Adebusola B. Alabi, Anna Ferré-Mateu, Aaron J. Romanowsky, Jean P. Brodie, Duncan A. Forbes, Asher Wasserman, Sabine Bellstedt, Ignacio Martín-Navarro, Viraj Pandya, Maria B. Stone, Nobuhiro Okabe 2018 University of California Observatories

Origins Of Ultradiffuse Galaxies In The Coma Cluster – I. Constraints From Velocity Phase Space, Adebusola B. Alabi, Anna Ferré-Mateu, Aaron J. Romanowsky, Jean P. Brodie, Duncan A. Forbes, Asher Wasserman, Sabine Bellstedt, Ignacio Martín-Navarro, Viraj Pandya, Maria B. Stone, Nobuhiro Okabe

Aaron J. Romanowsky

We use Keck/DEIMOS spectroscopy to confirm the cluster membership of 16 ultradiffuse galaxies (UDGs) in the Coma cluster, bringing the total number of spectroscopically confirmed UDGs from the Yagi et al. (Y16) catalogue to 25. We also identify a new cluster background UDG, confirming that most (∼95 per cent) of the UDGs in the Y16 catalogue belong to the Coma cluster. In this pilot study of Coma UDGs in velocity phase space, we find evidence of a diverse origin for Coma cluster UDGs, similar to normal dwarf galaxies. Some UDGs in our sample are consistent with being late infalls ...


The Periglacial Landscape Of Mars: Insight Into The 'Decameter-Scale Rimmed Depressions' In Utopia Planitia, Arya Bina 2018 The University of Western Ontario

The Periglacial Landscape Of Mars: Insight Into The 'Decameter-Scale Rimmed Depressions' In Utopia Planitia, Arya Bina

Electronic Thesis and Dissertation Repository

Currently, Mars appears to be in a ‘frozen’ and ‘dry’ state, with the clear majority of the planet’s surface maintaining year-round sub-zero temperatures. However, the discovery of features consistent with landforms found in periglacial environments on Earth, suggests a climate history for Mars that may have involved freeze and thaw cycles. Such landforms include hummocky, polygonised, scalloped, and pitted terrains, as well as ice-rich deposits and gullies, along the mid- to high-latitude bands, typically with no lower than 20o N/S. The detection of near-surface and surface ice via the Phoenix lander, excavation of ice via recent impact cratering ...


The Distance Of The Dark Matter Deficient Galaxy Ngc 1052–Df2, Pieter van Dokkum, Shany Danieli, Yotam Cohen, Aaron Romanowsky, Charlie Conroy 2018 Yale University

The Distance Of The Dark Matter Deficient Galaxy Ngc 1052–Df2, Pieter Van Dokkum, Shany Danieli, Yotam Cohen, Aaron Romanowsky, Charlie Conroy

Faculty Publications

We recently inferred that the galaxy NGC 1052–DF2 has little or no dark matter and a rich system of unusual globular clusters. We assumed that the galaxy is a satellite of the luminous elliptical galaxy NGC 1052 at ≈20 Mpc, on the basis of its surface brightness fluctuations (SBFs) distance of 19.0 ± 1.7 Mpc, its radial velocity of ≈1800 km s−1, and its projected position. Here we analyze the color–magnitude diagram (CMD) of NGC 1052–DF2, following the suggestion by Trujillo et al. that the tip of the red giant branch (TRGB) can be detected ...


Parametric Study Of The Rossby Wave Instability In A Two-Dimensional Barotropic Disk. Ii. Nonlinear Calculations, Tomohiro Ono, Takayuki Muto, Kengo Tomida, Zhaohuan Zhu 2018 Osaka University

Parametric Study Of The Rossby Wave Instability In A Two-Dimensional Barotropic Disk. Ii. Nonlinear Calculations, Tomohiro Ono, Takayuki Muto, Kengo Tomida, Zhaohuan Zhu

Physics & Astronomy Faculty Publications

Vortices in protoplanetary disks have attracted attention since the discovery of lopsided structures. One of the possible mechanisms for producing vortices is the Rossby wave instability (RWI). In our previous work, we have performed detailed linear stability analyses of the RWI with various initial conditions. In this paper, we perform numerical simulations of the vortex formation by the RWI in two-dimensional barotropic disks using the Athena++ code. As initial conditions, we consider axisymmetric disks with a Gaussian surface density bump of various contrasts and half-widths. Perturbations grow as expected from the linear stability analyses in the linear and weakly nonlinear ...


Understanding The Death Of Massive Stars Using An Astrophysical Transients Observatory, Peter W. Roming, Eddie Baron, Amanda J. Bayless, Volker Bromm, Peter J. Brown, Michael W. Davis, Anastasia Fialkov, Brian Fleming, Kevin France, Chris L. Fryer, Thomas K. Greathouse, Jed J. Hancock, D. Andrew Howell, Andrew J. Levan, Abraham Loeb, Raffaella Margutti, Mark L. McConnell, Paul T. O'Brien, Julian P. Osborne, Daniel A. Perley, Eric M. Schlegel, Rhaana L. C. Starling, Nial R. Tanvir, Mark Tapley, Patrick A. Young, Bing Zhang 2018 Southwest Research Institute

Understanding The Death Of Massive Stars Using An Astrophysical Transients Observatory, Peter W. Roming, Eddie Baron, Amanda J. Bayless, Volker Bromm, Peter J. Brown, Michael W. Davis, Anastasia Fialkov, Brian Fleming, Kevin France, Chris L. Fryer, Thomas K. Greathouse, Jed J. Hancock, D. Andrew Howell, Andrew J. Levan, Abraham Loeb, Raffaella Margutti, Mark L. Mcconnell, Paul T. O'Brien, Julian P. Osborne, Daniel A. Perley, Eric M. Schlegel, Rhaana L. C. Starling, Nial R. Tanvir, Mark Tapley, Patrick A. Young, Bing Zhang

Physics & Astronomy Faculty Publications

The death of massive stars, manifested as gamma-ray bursts and core-collapse supernovae, critically influence how the universe formed and evolves. Despite their fundamental importance, our understanding of these enigmatic objects is severely limited. We have performed a concept study of an Astrophysical Transient Observatory (ATO) that will rapidly facilitate an expansion of our understanding of these objects. ATO combines a very wide-field X-ray telescope, a near-infrared telescope, a multi-mode ultraviolet instrument, and a rapidly slewing spacecraft to realize two primary goals: (1) characterize the highest-redshift massive stars and their environments, and (2) constrain the poorly understood explosion mechanism of massive ...


The Distance Of The Dark Matter Deficient Galaxy Ngc 1052–Df2, Pieter van Dokkum, Shany Danieli, Yotam Cohen, Aaron J. Romanowsky, Charlie Conroy 2018 Yale University

The Distance Of The Dark Matter Deficient Galaxy Ngc 1052–Df2, Pieter Van Dokkum, Shany Danieli, Yotam Cohen, Aaron J. Romanowsky, Charlie Conroy

Aaron J. Romanowsky

We recently inferred that the galaxy NGC 1052–DF2 has little or no dark matter and a rich system of unusual globular clusters. We assumed that the galaxy is a satellite of the luminous elliptical galaxy NGC 1052 at ≈20 Mpc, on the basis of its surface brightness fluctuations (SBFs) distance of 19.0 ± 1.7 Mpc, its radial velocity of ≈1800 km s−1, and its projected position. Here we analyze the color–magnitude diagram (CMD) of NGC 1052–DF2, following the suggestion by Trujillo et al. that the tip of the red giant branch (TRGB) can be detected ...


Synchrotron Radiation From Electrons With A Pitch-Angle Distribution, Yuan-Pei Yang, Bing Zhang 2018 Chinese Academy of Sciences; University of Nevada, Las Vegas; KIAA-CAS Fellow

Synchrotron Radiation From Electrons With A Pitch-Angle Distribution, Yuan-Pei Yang, Bing Zhang

Physics & Astronomy Faculty Publications

In most astrophysical processes involving synchrotron radiation, the pitch-angle distribution of the electrons is assumed to be isotropic. However, if electrons are accelerated anisotropically, e.g., in a relativistic shock wave with an ordered magnetic field or in magnetic reconnection regions, the electron pitch angles might be anisotropic. In this Letter, we study synchrotron radiation from electrons with a pitch-angle distribution with respect to a large-scale uniform magnetic field. Assuming that the pitch-angle distribution is normal with a scatter of σ p and that the viewing direction is where the pitch-angle direction peaks, we find that for electrons with a ...


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