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- Protoplanetary disks (13)
- Hydrodynamics (11)
- Gamma-ray burst: General (7)
- Radiation mechanisms: Non-thermal (7)
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- Planets and satellites: Formation (6)
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- Planets and satellites: detection (2)
- Planets and satellites: dynamical evolution and stability (2)
- Quasars: General (2)
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Articles 1 - 30 of 59
Full-Text Articles in Physical Sciences and Mathematics
The Disk Substructures At High Angular Resolution Project (Dsharp). I. Motivation, Sample, Calibration, And Overview, Sean M. Andrews, Jane Huang, Laura M. Pérez, Andrea Isella, Cornelis P. Dullemond, Nicolás T. Kurtovic, Viviana V. Guzmán, John M. Carpenter, David J. Wilner, Shangjia Zhang, Zhaohuan Zhu, Tilman Birstiel, Xue-Ning Bai, Myriam Benisty, A. Meredith Hughes, Karin I. Öberg, Luca Ricci
The Disk Substructures At High Angular Resolution Project (Dsharp). I. Motivation, Sample, Calibration, And Overview, Sean M. Andrews, Jane Huang, Laura M. Pérez, Andrea Isella, Cornelis P. Dullemond, Nicolás T. Kurtovic, Viviana V. Guzmán, John M. Carpenter, David J. Wilner, Shangjia Zhang, Zhaohuan Zhu, Tilman Birstiel, Xue-Ning Bai, Myriam Benisty, A. Meredith Hughes, Karin I. Öberg, Luca Ricci
Physics & Astronomy Faculty Research
We introduce the Disk Substructures at High Angular Resolution Project (DSHARP), one of the initial Large Programs conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The primary goal of DSHARP is to find and characterize substructures in the spatial distributions of solid particles for a sample of 20 nearby protoplanetary disks, using very high resolution (~0 035, or 5 au, FWHM) observations of their 240 GHz (1.25 mm) continuum emission. These data provide a first homogeneous look at the small-scale features in disks that are directly relevant to the planet formation process, quantifying their prevalence, morphologies, spatial scales, spacings, symmetry, …
The Disk Substructures At High Angular Resolution Project (Dsharp). Ix. A High-Definition Study Of The Hd 163296 Planet-Forming Disk, Andrea Isella, Jane Huang, Sean M. Andrews, Cornelis P. Dellemond, Tilman Birnstiel, Shangjia Zhang, Zhaohuan Zhu, Viviana V. Guzmán, Laura M. Pérez, Xue-Ning Bai, Myriam Benisty, John M. Carpenter, Luca Ricci, David J. Wilner
The Disk Substructures At High Angular Resolution Project (Dsharp). Ix. A High-Definition Study Of The Hd 163296 Planet-Forming Disk, Andrea Isella, Jane Huang, Sean M. Andrews, Cornelis P. Dellemond, Tilman Birnstiel, Shangjia Zhang, Zhaohuan Zhu, Viviana V. Guzmán, Laura M. Pérez, Xue-Ning Bai, Myriam Benisty, John M. Carpenter, Luca Ricci, David J. Wilner
Physics & Astronomy Faculty Research
The Atacama Large Millimeter/submillimeter Array observations of protoplanetary disks acquired by the Disk Substructure at High Angular Resolution Project resolve the dust and gas emission on angular scales as small as 3 astronomical units, offering an unprecedented detailed view of the environment where planets form. In this Letter, we present and discuss observations of the HD 163296 protoplanetary disk that imaged the 1.25 mm dust continuum and 12CO J = 2–1 rotational line emission at a spatial resolution of 4 and 10 au, respectively. The continuum observations resolve and allow us to characterize the previously discovered dust rings at radii …
The Disk Substructures At High Angular Resolution Project (Dsharp). Iii. Spiral Structures In The Millimeter Continuum Of The Elias 27, Im Lup, And Waoph 6 Disks, Jane Huang, Sean M. Andrews, Laura M. Pérez, Zhaohuan Zhu, Cornelis P. Dullemond, Andrea Isella, Myriam Benisty, Xue-Ning Bai, Tilman Birnstiel, John M. Carpenter, Viviana V. Guzmán, A. Meredith Hughes, Karin I. Öberg, Luca Ricci, David J. Wilner, Shangjia Zhang
The Disk Substructures At High Angular Resolution Project (Dsharp). Iii. Spiral Structures In The Millimeter Continuum Of The Elias 27, Im Lup, And Waoph 6 Disks, Jane Huang, Sean M. Andrews, Laura M. Pérez, Zhaohuan Zhu, Cornelis P. Dullemond, Andrea Isella, Myriam Benisty, Xue-Ning Bai, Tilman Birnstiel, John M. Carpenter, Viviana V. Guzmán, A. Meredith Hughes, Karin I. Öberg, Luca Ricci, David J. Wilner, Shangjia Zhang
Physics & Astronomy Faculty Research
We present an analysis of Atacama Large Millimeter/submillimeter Array 1.25 mm continuum observations of spiral structures in three protoplanetary disks from the Disk Substructures at High Angular Resolution Project. See full text for full abstract.
The Disk Substructures At High Angular Resolution Project (Dsharp). Ii. Characteristics Of Annular Substructures, Jane Huang, Sean M. Andrews, Cornelis P. Dellemond, Andrea Isella, Laura M. Pérez, Viviana V. Guzmán, Karin I. Öberg, Zhaohuan Zhu, Shangjia Zhang, Xue-Ning Bai, Myriam Benisty, Tilman Birstiel, John M. Carpenter, A. Meredith Hughes, Luca Ricci, Erik Weaver, David J. Wilner
The Disk Substructures At High Angular Resolution Project (Dsharp). Ii. Characteristics Of Annular Substructures, Jane Huang, Sean M. Andrews, Cornelis P. Dellemond, Andrea Isella, Laura M. Pérez, Viviana V. Guzmán, Karin I. Öberg, Zhaohuan Zhu, Shangjia Zhang, Xue-Ning Bai, Myriam Benisty, Tilman Birstiel, John M. Carpenter, A. Meredith Hughes, Luca Ricci, Erik Weaver, David J. Wilner
Physics & Astronomy Faculty Research
The Disk Substructures at High Angular Resolution Project (DSHARP) used ALMA to map the 1.25 mm continuum of protoplanetary disks at a spatial resolution of ~5 au. We present a systematic analysis of annular substructures in the 18 single-disk systems targeted in this survey. No dominant architecture emerges from this sample; instead, remarkably diverse morphologies are observed. Annular substructures can occur at virtually any radius where millimeter continuum emission is detected and range in widths from a few astronomical units to tens of astronomical units. Intensity ratios between gaps and adjacent rings range from near-unity to just a few percent. …
The Disk Substructures At High Angular Resolution Project (Dsharp). Vii. The Planet–Disk Interactions Interpretation, Shangjia Zhang, Zhaohuan Zhu, Jane Huang, Viviana V. Guzmán, Sean M. Andrews, Tilman Birnstiel, Cornelis P. Dullemond, John M. Carpenter, Andrea Isella, Laura M. Pérez, Myriam Benisty, David J. Wilner, Clément Baruteau, Xue-Ning Bai, Luca Ricci
The Disk Substructures At High Angular Resolution Project (Dsharp). Vii. The Planet–Disk Interactions Interpretation, Shangjia Zhang, Zhaohuan Zhu, Jane Huang, Viviana V. Guzmán, Sean M. Andrews, Tilman Birnstiel, Cornelis P. Dullemond, John M. Carpenter, Andrea Isella, Laura M. Pérez, Myriam Benisty, David J. Wilner, Clément Baruteau, Xue-Ning Bai, Luca Ricci
Physics & Astronomy Faculty Research
The Disk Substructures at High Angular Resolution Project (DSHARP) provides a large sample of protoplanetary disks with substructures that could be induced by young forming planets. To explore the properties of planets that may be responsible for these substructures, we systematically carry out a grid of 2D hydrodynamical simulations, including both gas and dust components. We present the resulting gas structures, including the relationship between the planet mass, as well as (1) the gaseous gap depth/width and (2) the sub/super-Keplerian motion across the gap. We then compute dust continuum intensity maps at the frequency of the DSHARP observations. We provide …
The Disk Substructures At High Angular Resolution Project (Dsharp). Vi. Dust Trapping In Thin-Ringed Protoplanetary Disks, Cornelis P. Dullemond, Tilman Birnstiel, Jane Huang, Nicolás T. Kurtovic, Sean M. Andrews, Viviana V. Guzmán, Laura M. Pérez, Andrea Isella, Zhaohuan Zhu, Myriam Benisty, David J. Wilner, Xue-Ning Bai, John M. Carpenter, Shangjia Zhang, Luca Ricci
The Disk Substructures At High Angular Resolution Project (Dsharp). Vi. Dust Trapping In Thin-Ringed Protoplanetary Disks, Cornelis P. Dullemond, Tilman Birnstiel, Jane Huang, Nicolás T. Kurtovic, Sean M. Andrews, Viviana V. Guzmán, Laura M. Pérez, Andrea Isella, Zhaohuan Zhu, Myriam Benisty, David J. Wilner, Xue-Ning Bai, John M. Carpenter, Shangjia Zhang, Luca Ricci
Physics & Astronomy Faculty Research
A large fraction of the protoplanetary disks observed with ALMA display multiple well-defined and nearly perfectly circular rings in the continuum, in many cases with substantial peak-to-valley contrast. The DSHARP campaign shows that several of these rings are very narrow in radial extent. In this Letter we test the hypothesis that these dust rings are caused by dust trapping in radial pressure bumps, and if confirmed, put constraints on the physics of the dust trapping mechanism. We model this process analytically in 1D, assuming axisymmetry. By comparing this model to the data, we find that all rings are consistent with …
The Disk Substructures At High Angular Resolution Program (Dsharp). Viii. The Rich Ringed Substructures In The As 209 Disk, Viviana V. Guzmán, Jane Huang, Sean M. Andrews, Andrea Isella, Laura M. Pérez, John M. Carpenter, Cornelis P. Dullemond, Luca Ricci, Tilman Birnstiel, Shangjia Zhang, Zhaohuan Zhu, Xue-Ning Bai, Myriam Benisty, Karin I. Öberg, David J. Wilner
The Disk Substructures At High Angular Resolution Program (Dsharp). Viii. The Rich Ringed Substructures In The As 209 Disk, Viviana V. Guzmán, Jane Huang, Sean M. Andrews, Andrea Isella, Laura M. Pérez, John M. Carpenter, Cornelis P. Dullemond, Luca Ricci, Tilman Birnstiel, Shangjia Zhang, Zhaohuan Zhu, Xue-Ning Bai, Myriam Benisty, Karin I. Öberg, David J. Wilner
Physics & Astronomy Faculty Research
The Disk Substructures at High Angular Resolution Program (DSHARP). VIII. The Rich Ringed Substructures in the AS 209 Disk
The Disk Substructures At High Angular Resolution Project (Dsharp). Iv. Characterizing Substructures And Interactions In Disks Around Multiple Star Systems, Nicolás T. Kurtovic, Laura M. Pérez, Myriam Benisty, Zhaohuan Zhu, Shangjia Zhang, Jane Huang, Sean M. Andrews, Cornelis P. Dullemond, Andrea Isella, Xue-Ning Bai, John M. Carpenter, Viviana V. Guzmán, Luca Ricci, David J. Wilner
The Disk Substructures At High Angular Resolution Project (Dsharp). Iv. Characterizing Substructures And Interactions In Disks Around Multiple Star Systems, Nicolás T. Kurtovic, Laura M. Pérez, Myriam Benisty, Zhaohuan Zhu, Shangjia Zhang, Jane Huang, Sean M. Andrews, Cornelis P. Dullemond, Andrea Isella, Xue-Ning Bai, John M. Carpenter, Viviana V. Guzmán, Luca Ricci, David J. Wilner
Physics & Astronomy Faculty Research
To characterize the substructures induced in protoplanetary disks by the interaction between stars in multiple systems, we study the 1.25 mm continuum and the 12CO(J = 2–1) spectral line emission of the triple systems HT Lup and AS 205, at scales of ≈5 au, as part of the "Disk Substructures at High Angular Resolution Project" (DSHARP). In the continuum emission, we find two symmetric spiral arms in the disk around AS 205 N, with a pitch angle of 14°, while the southern component AS 205 S, itself a spectroscopic binary, is surrounded by a compact inner disk and a bright …
The Disk Substructures At High Angular Resolution Project (Dsharp). X. Multiple Rings, A Misaligned Inner Disk, And A Bright Arc In The Disk Around The T Tauri Star Hd 143006, Laura M. Pérez, Myriam Benisty, Sean M. Andrews, Andrea Isella, Cornelis P. Dellemond, Jane Huang, Nicolás T. Kurtovic, Viviana V. Guzmán, Zhaohuan Zhu, Tilman Birnstiel, Shangjia Zhang, John M. Carpenter, David J. Wilner, Luca Ricci, Xue-Ning Bai, Erik Weaver, Karin I. Öberg
The Disk Substructures At High Angular Resolution Project (Dsharp). X. Multiple Rings, A Misaligned Inner Disk, And A Bright Arc In The Disk Around The T Tauri Star Hd 143006, Laura M. Pérez, Myriam Benisty, Sean M. Andrews, Andrea Isella, Cornelis P. Dellemond, Jane Huang, Nicolás T. Kurtovic, Viviana V. Guzmán, Zhaohuan Zhu, Tilman Birnstiel, Shangjia Zhang, John M. Carpenter, David J. Wilner, Luca Ricci, Xue-Ning Bai, Erik Weaver, Karin I. Öberg
Physics & Astronomy Faculty Research
We present a detailed analysis of new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the disk around the T-Tauri star HD 143006, which at 46 mas (7.6 au) resolution reveals new substructures in the 1.25 mm continuum emission. The disk resolves into a series of concentric rings and gaps, together with a bright arc exterior to the rings that resembles hydrodynamical simulations of a vortex and a bridge-like feature connecting the two innermost rings. Although our 12CO observations at similar spatial resolution do not show obvious substructure, they reveal an inner disk depleted of CO emission. From the continuum emission …
The Disk Substructures At High Angular Resolution Project (Dsharp). V. Interpreting Alma Maps Of Protoplanetary Disks In Terms Of A Dust Model, Tilman Birnstiel, Cornelis P. Dullemond, Zhaohuan Zhu, Sean M. Andrews, Xue-Ning Bai, David J. Wilner, John M. Carpenter, Jane Huang, Andrea Isella, Myriam Benisty, Laura M. Pérez, Shangjia Zhang
The Disk Substructures At High Angular Resolution Project (Dsharp). V. Interpreting Alma Maps Of Protoplanetary Disks In Terms Of A Dust Model, Tilman Birnstiel, Cornelis P. Dullemond, Zhaohuan Zhu, Sean M. Andrews, Xue-Ning Bai, David J. Wilner, John M. Carpenter, Jane Huang, Andrea Isella, Myriam Benisty, Laura M. Pérez, Shangjia Zhang
Physics & Astronomy Faculty Research
The Disk Substructures at High Angular Resolution Project (DSHARP) is the largest homogeneous high-resolution (~0 035, or ~5 au) disk continuum imaging survey with the Atacama Large Millimeter/submillimeter Array (ALMA) so far. In the coming years, many more disks will be mapped with ALMA at similar resolution. Interpreting the results in terms of the properties and quantities of the emitting dusty material is, however, a very non-trivial task. This is in part due to the uncertainty in the dust opacities, an uncertainty that is not likely to be resolved any time soon. It is also partly due to the fact …
Bayesian Model Comparisons In Planetary Science, John Henry Boisvert
Bayesian Model Comparisons In Planetary Science, John Henry Boisvert
UNLV Theses, Dissertations, Professional Papers, and Capstones
Model comparison in the modern era allows us to use statistical methods that were previously difficult with older machines. I present a state-of-the-art model comparison code that uses modern Bayesian statistics to measure the Bayes factor between two competing models. The Bayes factor is the ratio of the probability of the data given one model to the probability of the data given another model. My code was used to compare models in five problems in planetary science. The first three pertain to radial velocity exoplanet data. There is a degeneracy in the radial velocity exoplanet signal between a single planet …
Toward An Understanding Of Grb Prompt Emission Mechanism. Ii. Patterns Of Peak Energy Evolution And Their Connection To Spectral Lags, Z. Lucas Uhm, Bing Zhang, Judith Racusin
Toward An Understanding Of Grb Prompt Emission Mechanism. Ii. Patterns Of Peak Energy Evolution And Their Connection To Spectral Lags, Z. Lucas Uhm, Bing Zhang, Judith Racusin
Physics & Astronomy Faculty Research
The prompt emission phase of gamma-ray bursts (GRBs) exhibits two distinct patterns of the peak energy (E p ) evolution, i.e., time-resolved spectral analyses of νF ν spectra of broad pulses reveal (1) "hard-to-soft" and (2) "flux-tracking" patterns of E p evolution in time, the physical origin of which still remains not well understood. We show here that these two patterns can be successfully reproduced within a simple physical model invoking synchrotron radiation in a bulk-accelerating emission region. We show further that the evolution patterns of the peak energy have, in fact, direct connections to the existence of two different …
Inclined Massive Planets In A Protoplanetary Disc: Gap Opening, Disc Breaking, And Observational Signatures, Zhaohuan Zhu
Inclined Massive Planets In A Protoplanetary Disc: Gap Opening, Disc Breaking, And Observational Signatures, Zhaohuan Zhu
Physics & Astronomy Faculty Research
We carry out 3D hydrodynamical simulations to study planet–disc interactions for inclined high-mass planets, focusing on the disc’s secular evolution induced by the planet. We find that, when the planet is massive enough and the induced gap is deep enough, the disc inside the planet’s orbit breaks from the outer disc. The inner and outer discs precess around the system’s total angular momentum vector independently at different precession rates, which causes significant disc misalignment. We derive the analytical formulae, which are also verified numerically, for: (1) the relationship between the planet mass and the depth/width of the induced gap, (2) …
Cm-Wavelength Obserations Of Mwc 758: Resolved Dust Trapping In A Vortex, Simon Casassus, Sebastián Marino, Wladimir Lyra, Clément Baruteau, Matías Vidal, Alwyn Wootten, Sebastián Pérez, Felipe Alarcon, Marcelo Barraza, Miguel Cárcamo, Ruobing Dong, Anibal Sierra, Zhaohuan Zhu, Luca Ricci, Valentin Christiaens, Lucas Cieza
Cm-Wavelength Obserations Of Mwc 758: Resolved Dust Trapping In A Vortex, Simon Casassus, Sebastián Marino, Wladimir Lyra, Clément Baruteau, Matías Vidal, Alwyn Wootten, Sebastián Pérez, Felipe Alarcon, Marcelo Barraza, Miguel Cárcamo, Ruobing Dong, Anibal Sierra, Zhaohuan Zhu, Luca Ricci, Valentin Christiaens, Lucas Cieza
Physics & Astronomy Faculty Research
The large crescents imaged by ALMA in transition discs suggest that azimuthal dust trapping concentrates the larger grains, but centimetre–wavelengths continuum observations are required to map the distribution of the largest observable grains. A previous detection at ∼1 cm of an unresolved clump along the outer ring of MWC 758 (Clump 1), and buried inside more extended sub-mm continuum, motivates followup VLA observations. Deep multiconfiguration integrations reveal the morphology of Clump 1 and additional cm-wave components that we characterize via comparison with a deconvolution of recent 342 GHz data (∼1 mm). ... See full text for complete abstract.
Photospheric Radius Evolution Of Homologous Explosions, Liang-Duan Liu, Bing Zhang, Ling-Jun Wang, Zi-Gao Dai
Photospheric Radius Evolution Of Homologous Explosions, Liang-Duan Liu, Bing Zhang, Ling-Jun Wang, Zi-Gao Dai
Physics & Astronomy Faculty Research
Recent wide-field surveys discovered new types of peculiar optical transients that showed diverse behaviors of the evolution of photospheric properties. We develop a general theory of homologous explosions with constant opacity, paying special attention to the evolution of the photospheric radius R ph. We find that regardless of the density distribution profile, R ph always increases early on and decreases at late times. This result does not depend on the radiation and cooling processes inside the ejecta. The general rising/falling behavior of R ph can be used to quickly diagnose whether the source originates from a supernova-like explosion. The shape …
Diffusion And Concentration Of Solids In The Dead Zone Of A Protoplanetary Disk, Chao-Chin Yang, Mordecai-Mark Mac Low, Anders Johansen
Diffusion And Concentration Of Solids In The Dead Zone Of A Protoplanetary Disk, Chao-Chin Yang, Mordecai-Mark Mac Low, Anders Johansen
Physics & Astronomy Faculty Research
The streaming instability is a promising mechanism to drive the formation of planetesimals in protoplanetary disks. To trigger this process, it has been argued that sedimentation of solids onto the mid-plane needs to be efficient, and therefore that a quiescent gaseous environment is required. It is often suggested that dead-zone or disk-wind structure created by non-ideal magnetohydrodynamical (MHD) effects meets this requirement. However, simulations have shown that the mid-plane of a dead zone is not completely quiescent. In order to examine the concentration of solids in such an environment, we use the local-shearing-box approximation to simulate a particlegas system with …
Bunching Coherent Curvature Radiation In Three-Dimensional Magnetic Field Geometry: Application To Pulsars And Fast Radio Bursts, Yuan-Pei Yang, Bing Zhang
Bunching Coherent Curvature Radiation In Three-Dimensional Magnetic Field Geometry: Application To Pulsars And Fast Radio Bursts, Yuan-Pei Yang, Bing Zhang
Physics & Astronomy Faculty Research
The extremely high brightness temperatures of pulsars and fast radio bursts (FRBs) require their radiation mechanisms to be coherent. Coherent curvature radiation from bunches has been long discussed as the mechanism for radio pulsars and recently for FRBs. Assuming that bunches are already generated in pulsar magnetospheres, we calculate the spectrum of coherent curvature radiation under a three-dimensional magnetic field geometry. Different from previous works assuming parallel trajectories and a monoenergetic energy distribution of electrons, we consider a bunch characterized by its length, curvature radius of the trajectory family, bunch opening angle, and electron energy distribution. We find that the …
A Long-Lived Neutron Star Merger Remnant In Gw170817: Constraints And Clues From X-Ray Observations, L Piro, E Troja, Bing Zhang, G Ryan, H Van Eerten, R Ricci, M H. Wieringa, A Tiengo, N R. Butler, S B. Cenko, O D. Fox, H G. Khandrika, G Novara, A Rossi, T Sakamoto
A Long-Lived Neutron Star Merger Remnant In Gw170817: Constraints And Clues From X-Ray Observations, L Piro, E Troja, Bing Zhang, G Ryan, H Van Eerten, R Ricci, M H. Wieringa, A Tiengo, N R. Butler, S B. Cenko, O D. Fox, H G. Khandrika, G Novara, A Rossi, T Sakamoto
Physics & Astronomy Faculty Research
Multimessenger observations of GW170817 have not conclusively established whether the merger remnant is a black hole (BH) or a neutron star (NS). We show that a long-lived magnetized NS with a poloidal field B ≈ 1012 G is fully consistent with the electromagnetic dataset, when spin-down losses are dominated by gravitational wave (GW) emission. ... See full text for complete abstract.
Fast Radio Burst Energetics And Detectability From High Redshifts, Bing Zhang
Fast Radio Burst Energetics And Detectability From High Redshifts, Bing Zhang
Physics & Astronomy Faculty Research
We estimate the upper limit redshifts of known fast radio bursts (FRBs) using the dispersion measure (DM)-redshift (z) relation and derive the upper limit peak luminosity L p and energy E of FRBs within the observational band. The average z upper limits range from 0.17 to 3.10, the average L p upper limits range from 1.24 × 1042 erg s−1 to 7.80 × 1044 erg s−1, and the average E upper limits range from 6.91 × 1039 erg to 1.94 × 1042 erg. FRB 160102 with DM = 2596.1 ± 0.3 pc cm−3 likely has a redshift greater than 3. …
Streaming Instability Of Multiple Particle Species In Protoplanetary Disks, Noemi Schaffer, Chao-Chin Yang, Anders Johansen
Streaming Instability Of Multiple Particle Species In Protoplanetary Disks, Noemi Schaffer, Chao-Chin Yang, Anders Johansen
Physics & Astronomy Faculty Research
The radial drift and diffusion of dust particles in protoplanetary disks affect both the opacity and temperature of such disks, as well as the location and timing of planetesimal formation. In this paper, we present results of numerical simulations of particle-gas dynamics in protoplanetary disks that include dust grains with various size distributions. We have considered three scenarios in terms of particle size ranges, one where the Stokes number τs = 10−1−100, one where τs = 10−4−10−1, and finally one where τs= 10−3−100. Moreover, we considered both discrete and continuous distributions in particle size. In accordance with previous works we …
A Bayesian Framework For Exoplanet Direct Detection And Non-Detection, Jean-Baptiste Ruffio, Dimitri Mawet, Ian Czekala, Bruce Macintosh, Robert J. De Rosa, Garreth Ruane, Michael Bottom, Laurent Pueyo, Jason J. Wang, Lea Hirsch, Zhaohuan Zhu, Eric L. Nielsen
A Bayesian Framework For Exoplanet Direct Detection And Non-Detection, Jean-Baptiste Ruffio, Dimitri Mawet, Ian Czekala, Bruce Macintosh, Robert J. De Rosa, Garreth Ruane, Michael Bottom, Laurent Pueyo, Jason J. Wang, Lea Hirsch, Zhaohuan Zhu, Eric L. Nielsen
Physics & Astronomy Faculty Research
Rigorously quantifying the information in high-contrast imaging data is important for informing follow-up strategies to confirm the substellar nature of a point source, constraining theoretical models of planet–disk interactions, and deriving planet occurrence rates. However, within the exoplanet direct imaging community, non-detections have almost exclusively been defined using a frequentist detection threshold (i.e., contrast curve) and associated completeness. This can lead to conceptual inconsistencies when included in a Bayesian framework. A Bayesian upper limit is such that the true value of a parameter lies below this limit with a certain probability. The associated probability is the integral of the posterior …
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
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 Research
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 maximum …
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
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 Research
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 …
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
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 Research
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 …
Time-Dependent Radiation-Driven Winds, Sergei Dyda, Daniel Proga
Time-Dependent Radiation-Driven Winds, Sergei Dyda, Daniel Proga
Physics & Astronomy Faculty Research
We study temporal variability of radiation-driven winds using one-dimensional, time-dependent simulations and an extension of the classic theory of line-driven winds developed by Castor Abbott & Klein. We drive the wind with a sinusoidally varying radiation field and find that after a relaxation time, determined by the propagation time for waves to move out of the acceleration zone of the wind, the solution settles into a periodic state. Winds driven at frequencies much higher than the dynamical frequency behave like stationary winds with time averaged radiation flux, whereas winds driven at much lower frequencies oscillate between the high and low …
Survivability Of Moon Systems Around Ejected Gas Giants, Ian Rabago, Jason H. Steffen
Survivability Of Moon Systems Around Ejected Gas Giants, Ian Rabago, Jason H. Steffen
Physics & Astronomy Faculty Research
We examine the effects that planetary encounters have on the moon systems of ejected gas giant planets. We conduct a suite of numerical simulations of planetary systems containing three Jupiter-mass planets (with the innermost planet at 3 AU) up to the point where a planet is ejected from the system. The ejected planet has an initial system of 100 test-particle moons. We determine the survival probability of moons at different distances from their host planet, measure the final distribution of orbital elements, examine the stability of resonant configurations, and characterize the properties of moons that are stripped from the planets. …
Long-Lived Remnants From Binary Neutron Star Mergers, David Radice, Albino Perego, Sebastiano Bernuzzi, Bing Zhang
Long-Lived Remnants From Binary Neutron Star Mergers, David Radice, Albino Perego, Sebastiano Bernuzzi, Bing Zhang
Physics & Astronomy Faculty Research
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 …
Effects Of Radiation Field Geometry On Line Driven Disc Winds, Sergei Dyda, Daniel Proga
Effects Of Radiation Field Geometry On Line Driven Disc Winds, Sergei Dyda, Daniel Proga
Physics & Astronomy Faculty Research
We study line driven winds for models with different radial intensity profiles: standard Shakura–Sunyaev radiating thin discs, uniform intensity discs, and truncated discs where driving radiation is cut-off at some radius. We find that global outflow properties depend primarily on the total system luminosity but truncated discs can launch outflows with ∼2 times higher mass flux and ∼50 per cent faster outflow velocity than non-truncated discs with the same total radiation flux. Streamlines interior to the truncation radius are largely unaffected and carry the same momentum flux as non-truncated models whereas those far outside the truncation radius effectively carry no …
Survival Of Non-Coplanar, Closely Packed Planetary Systems After A Close Encounter, David R. Rice, Frederic A. Rasio, Jason H. Steffen
Survival Of Non-Coplanar, Closely Packed Planetary Systems After A Close Encounter, David R. Rice, Frederic A. Rasio, Jason H. Steffen
Physics & Astronomy Faculty Research
Planetary systems with more than two bodies will experience orbital crossings at a time related to the initial orbital separations of the planets. After a crossing, the system enters a period of chaotic evolution ending in the reshaping of the system’s architecture via planetary collisions or ejections. We carry out N-body integrations on a large number of systems with equally spaced planets (in units of the Hill radius) to determine the distribution of instability times for a given planet separation. We investigate both the time to the initiation of instability through a close encounter and the time to a planet--planet …
Magnetothermal Disc Winds In X-Ray Binaries: Poloidal Magnetic Fields Suppress Thermal Winds, Tim Waters, Daniel Proga
Magnetothermal Disc Winds In X-Ray Binaries: Poloidal Magnetic Fields Suppress Thermal Winds, Tim Waters, Daniel Proga
Physics & Astronomy Faculty Research
Magnetic, radiation pressure, and thermal driving are the three mechanisms capable of launching accretion disc winds. In X-ray binaries, radiation pressure is often not significant, as in many systems the luminosity is too low for driving due to continuum transitions yet too high for driving due to line transitions. This leaves thermal and magnetic driving as the contender launching mechanisms in these systems. Using ATHENA++, we perform axisymmetric ideal MHD simulations that include radiative heating and cooling processes appropriate for Compton heated winds to show that the inclusion of magnetic fields into a thermally driven wind has the opposite effect …