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- Protoplanetary disks (13)
- Hydrodynamics (10)
- Gamma-ray burst: General (7)
- Radiation mechanisms: Non-thermal (7)
- Accretion (6)
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- Planets and satellites: Formation (6)
- Accretion discs (5)
- Methods: Statistical (5)
- Planet-disk interactions (5)
- Protoplanetary discs (5)
- Gravitational waves (4)
- Techniques: High angular resolution (4)
- Dust, extinction (3)
- Instabilities (3)
- Planet-disc interactions (3)
- Planetary systems (3)
- Radio continuum: General (3)
- Binaries: General (2)
- Circumstellar matter (2)
- Instrumentation: High angular resolution (2)
- MHD (2)
- Methods: Numerical (2)
- Methods: numerical (2)
- Opacity (2)
- Planets and satellites: Detection (2)
- Planets and satellites: detection (2)
- Planets and satellites: dynamical evolution and stability (2)
- Quasars: General (2)
- Radiation mechanisms: Thermal (2)
- Stars: Massive (2)
Articles 31 - 55 of 55
Full-Text Articles in Physical Sciences and Mathematics
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
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 Research
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 …
Parametric Study Of The Rossby Wave Instability In A Two-Dimensional Barotropic Disk. Ii. Nonlinear Calculations, Tomohiro Ono, Takayuki Muto, Kengo Tomida, Zhaohuan Zhu
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 Research
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 …
Synchrotron Radiation From Electrons With A Pitch-Angle Distribution, Yuan-Pei Yang, Bing Zhang
Synchrotron Radiation From Electrons With A Pitch-Angle Distribution, Yuan-Pei Yang, Bing Zhang
Physics & Astronomy Faculty Research
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 Lorentz …
Warping A Protoplanetary Disc With A Planet On An Inclined Orbit, Rebecca Nealon, Giovanni Dipierro, Richard Alexander, Rebecca G. Martin, Chris Nixon
Warping A Protoplanetary Disc With A Planet On An Inclined Orbit, Rebecca Nealon, Giovanni Dipierro, Richard Alexander, Rebecca G. Martin, Chris Nixon
Physics & Astronomy Faculty Research
Recent observations of several protoplanetary discs have found evidence of departures from flat, circular motion in the inner regions of the disc. One possible explanation for these observations is a disc warp, which could be induced by a planet on a misaligned orbit. We present three-dimensional numerical simulations of the tidal interaction between a protoplanetary disc and a misaligned planet. For low planet masses, we show that our simulations accurately model the evolution of inclined planet orbit (up to moderate inclinations). For a planet massive enough to carve a gap, the disc is separated into two components and the gas …
Ttv-Determined Masses For Warm Jupiters And Their Close Planetary Companions, Dong-Hong Wu, Songhu Wang, Ji-Lin Zhou, Jason H. Steffen, Gregory Laughlin
Ttv-Determined Masses For Warm Jupiters And Their Close Planetary Companions, Dong-Hong Wu, Songhu Wang, Ji-Lin Zhou, Jason H. Steffen, Gregory Laughlin
Physics & Astronomy Faculty Research
Although the formation and the properties of hot Jupiters (with orbital periods P < 10 days) have attracted a great deal of attention, the origins of warm Jupiters (10 < P < 100 days) are less well studied. Using a transit timing analysis, we present the orbital parameters of five planetary systems containing warm Jupiters, Kepler 30, Kepler 117, Kepler 302, Kepler 487, and Kepler 418. Three of them, Kepler-30 c(M p = 549.4 ± 5.6 M ⊕), Kepler-117 c(M p = 702 ± 63 M ⊕), and Kepler 302 c(M p = 933 ± 527 M ⊕), are confirmed to be real warm Jupiters based on their mass. Insights drawn from the radius–temperature relationship lead to the inference that hot Jupiters and warm Jupiters can be roughly separated by T eff,c = 1123.7 ± 3.3 K. Also, T eff,c provides a good separation for Jupiters with companion fraction consistent with zero (T eff > T eff,c) and those with companion fraction significantly different from zero (T eff < T eff,c).
Circumbinary Discs Around Merging Stellar-Mass Black Holes, Rebecca G. Martin, Chris Nixon, Fu-Guo Xie, Andrew King
Circumbinary Discs Around Merging Stellar-Mass Black Holes, Rebecca G. Martin, Chris Nixon, Fu-Guo Xie, Andrew King
Physics & Astronomy Faculty Research
A circumbinary disc around a pair of merging stellar-mass black holes may be shocked and heated during the recoil of the merged hole, causing a near-simultaneous electromagnetic counterpart to the gravitational wave event. The shocks occur around the recoil radius, where the disc orbital velocity is equal to the recoil velocity. The amount of mass present near this radius at the time of the merger is critical in determining how much radiation is released. We explore the evolution of a circumbinary disc in two limits. First, we consider an accretion disc that feels no torque from the binary. The disc …
Characteristics Of Two-Episode Emission Patterns In Fermi Long Gamma-Ray Bursts, Lin Lan, Hou-Jun Lü, Shu-Qing Zhong, Hai-Ming Zhang, Jared Rice, Ji-Gui Cheng, Shen-Shi Du, Long Li, Jie Lin, Rui-Jing Lu, En-Wei Liang
Characteristics Of Two-Episode Emission Patterns In Fermi Long Gamma-Ray Bursts, Lin Lan, Hou-Jun Lü, Shu-Qing Zhong, Hai-Ming Zhang, Jared Rice, Ji-Gui Cheng, Shen-Shi Du, Long Li, Jie Lin, Rui-Jing Lu, En-Wei Liang
Physics & Astronomy Faculty Research
Two-episode emission components separated by quiescent gaps in the prompt emission of gamma-ray bursts (GRBs) have been observed in the Swift era, but there is a lack of spectral information due to the narrow energy band of the Swift/Burst Alert Telescope. In this paper, a systematic analysis of the spectral and temporal properties of the prompt emission of 101 Fermi/Gamma-ray Burst Monitor detected long GRBs show the existence of two-episode emission components in the light curves, with quiescent times of up to hundreds of seconds. We focus on investigating the differences of those two emission episodes. We find that the …
Rossby Vortices In Thin Magnetized Accretion Discs, L. Matilsky, Sergei Dyda, R. V. E. Lovelace, P. S. Lii
Rossby Vortices In Thin Magnetized Accretion Discs, L. Matilsky, Sergei Dyda, R. V. E. Lovelace, P. S. Lii
Physics & Astronomy Faculty Research
We study the Rossby wave instability (RWI) in a thin accretion disc threaded by an initially toroidal magnetic field using the magnetohydrodynamics (MHD) code PLUTO... See full text for full abstract.
Gamma-Ray Burst/Supernova Associations: Energy Partition And The Case Of A Magnetar Central Engine, Hon-Jun Lü, Lin Lan, Bing Zhang, En-Wei Liang, David Alexander Kann, Shen-Shi Du, Jun Shen
Gamma-Ray Burst/Supernova Associations: Energy Partition And The Case Of A Magnetar Central Engine, Hon-Jun Lü, Lin Lan, Bing Zhang, En-Wei Liang, David Alexander Kann, Shen-Shi Du, Jun Shen
Physics & Astronomy Faculty Research
The favored progenitor model for Gamma-ray Bursts (GRBs) with Supernova (SN) association is the core collapse of massive stars. One possible outcome of such a collapse is a rapidly spinning, strongly magnetized neutron star ("magnetar"). We systematically analyze the multi-wavelength data of GRB/SN associations detected by several instruments before 2017 June. Twenty GRB/SN systems have been confirmed via direct spectroscopic evidence or a clear light curve bump, as well as some spectroscopic evidence resembling a GRB-SN. We derive/collect the basic physical parameters of the GRBs and the SNe, and look for correlations among these parameters. We find that the peak …
Systematic Mischaracterization Of Exoplanetary System Dynamical Histories From A Model Degeneracy Near Mean-Motion Resonance, John H. Boisvert, Benjamin E. Nelson, Jason H. Steffen
Systematic Mischaracterization Of Exoplanetary System Dynamical Histories From A Model Degeneracy Near Mean-Motion Resonance, John H. Boisvert, Benjamin E. Nelson, Jason H. Steffen
Physics & Astronomy Faculty Research
There is a degeneracy in the radial velocity exoplanet signal between a single planet on an eccentric orbit and a two-planet system with a period ratio of 2:1. This degeneracy could lead to misunderstandings of the dynamical histories of planetary systems as well as measurements of planetary abundances if the correct architecture is not established. We constrain the rate of mischaracterization by analysing a sample of 60 non-transiting, radial velocity systems orbiting main-sequence stars from the NASA Exoplanet Archive (NASA Archive) using a new Bayesian model comparison pipeline. We find that 15 systems (25 per cent of our sample) show …
White Dwarf Pollution By Asteroids From Secular Resonances, Jeremy L. Smallwood, Rebecca G. Martin, Mario Livio, Stephen H. Lubow
White Dwarf Pollution By Asteroids From Secular Resonances, Jeremy L. Smallwood, Rebecca G. Martin, Mario Livio, Stephen H. Lubow
Physics & Astronomy Faculty Research
In the past few decades, observations have revealed signatures of metals polluting the atmospheres of white dwarfs. The diffusion time-scale for metals to sink from the atmosphere of a white dwarf is of the order of days for a hydrogen-dominated atmosphere. Thus, there must be a continuous supply of metal-rich material accreting onto these white dwarfs. We investigate the role of secular resonances that excite the eccentricity of asteroids allowing them to reach star-grazing orbits leading them to tidal disruption and the formation of a debris disc. Changes in the planetary system during the evolution of the star lead to …
What Powered The Optical Transient At2017gfo Associated With Gw170817?, Shao-Ze Li, Liang-Duan Liu, Yun-Wei Yu, Bing Zhang
What Powered The Optical Transient At2017gfo Associated With Gw170817?, Shao-Ze Li, Liang-Duan Liu, Yun-Wei Yu, Bing Zhang
Physics & Astronomy Faculty Research
The groundbreaking discovery of the optical transient AT2017gfo associated with GW170817 opens a unique opportunity to study the physics of double neutron star (NS) mergers. We argue that the standard interpretation of AT2017gfo as being powered by radioactive decay of r-process elements faces the challenge of simultaneously accounting for the peak luminosity and peak time of the event, as it is not easy to achieve the required high mass, and especially the low opacity of the ejecta required to fit the data. A plausible solution would be to invoke an additional energy source, which is probably provided by the merger …
Polar Alignment Of A Protoplanetary Disc Around An Eccentric Binary - Ii. Effect Of Binary And Disc Parameters, Rebecca G. Martin, Stephen H. Lubow
Polar Alignment Of A Protoplanetary Disc Around An Eccentric Binary - Ii. Effect Of Binary And Disc Parameters, Rebecca G. Martin, Stephen H. Lubow
Physics & Astronomy Faculty Research
In a recent paper Martin & Lubow showed that a circumbinary disc around an eccentric binary can undergo damped nodal oscillations that lead to the polar (perpendicular) alignment of the disc relative to the binary orbit. The disc angular momentum vector aligns to the eccentricity vector of the binary. We explore the robustness of this mechanism for a low-mass disc (0.001 of the binary mass) and its dependence on system parameters by means of hydrodynamic disc simulations. We describe how the evolution depends upon the disc viscosity, temperature, size, binary mass ratio, orbital eccentricity, and inclination. We compare results with …
The Eccentric Cavity, Triple Rings, Two-Armed Spirals, And Double Clumps Of The Mwc 758 Disk, Ruobing Dong, Sheng-Yuan Liu, Josh Eisner, Sean Andrews, Jeffrey Fung, Zhauhuan Zhu, Eugene Chiang, Jun Hashimoto, Hauyu Baobab Liu, Simon Casassus, Thomas Esposito, Yasuhiro Hasegawa, Takayuki Muto, Yaroslav Pavlyuchenkov, David Wilner, Eiji Akiyama, Motohide Tamura, John Wisniewski
The Eccentric Cavity, Triple Rings, Two-Armed Spirals, And Double Clumps Of The Mwc 758 Disk, Ruobing Dong, Sheng-Yuan Liu, Josh Eisner, Sean Andrews, Jeffrey Fung, Zhauhuan Zhu, Eugene Chiang, Jun Hashimoto, Hauyu Baobab Liu, Simon Casassus, Thomas Esposito, Yasuhiro Hasegawa, Takayuki Muto, Yaroslav Pavlyuchenkov, David Wilner, Eiji Akiyama, Motohide Tamura, John Wisniewski
Physics & Astronomy Faculty Research
Spatially resolved structures in protoplanetary disks hint at unseen planets. Previous imaging observations of the transitional disk around MWC 758 revealed an inner cavity, a ring-like outer disk, emission clumps, and spiral arms, all possibly generated by companions. We present ALMA dust continuum observations of MWC 758 at 0.87 mm wavelength with 43 × 39 mas angular resolution (6.9 × 6.2 au) and 20 μJy beam−1 rms. The central submillimeter emission cavity is revealed to be eccentric; once deprojected, its outer edge can be well fitted by an ellipse with an eccentricity of 0.1 and one focus on the star. …
The Origin Of The Prompt Emission For Short Grb 170817a: Photosphere Emission Or Synchrotron Emission?, Yan-Zhi Meng, Jin-Jun Geng, Bin-Bin Zhang, Jun-Jie Wei, Di Xiao, Liang-Duan Liu, He Gao, Xue-Feng Wu, En-Wei Liang, Yong-Feng Huang, Zi-Gao Dai, Bing Zhang
The Origin Of The Prompt Emission For Short Grb 170817a: Photosphere Emission Or Synchrotron Emission?, Yan-Zhi Meng, Jin-Jun Geng, Bin-Bin Zhang, Jun-Jie Wei, Di Xiao, Liang-Duan Liu, He Gao, Xue-Feng Wu, En-Wei Liang, Yong-Feng Huang, Zi-Gao Dai, Bing Zhang
Physics & Astronomy Faculty Research
The first gravitational-wave event from the merger of a binary neutron star system (GW170817) was detected recently. The associated short gamma-ray burst (GRB 170817A) has a low isotropic luminosity (~1047 erg s−1) and a peak energy E p ~ 145 keV during the initial main emission between −0.3 and 0.4 s. The origin of this short GRB is still under debate, but a plausible interpretation is that it is due to the off-axis emission from a structured jet. We consider two possibilities. First, since the best-fit spectral model for the main pulse of GRB 170817A is a cutoff power law …
The Allowed Parameter Space Of A Long-Lived Neutron Star As The Merger Remnant Of Gw170817, Shunke Ai, He Gao, Zi-Gao Dai, Xue-Feng Wu, Ang Li, Bing Zhang, Mu-Zi Li
The Allowed Parameter Space Of A Long-Lived Neutron Star As The Merger Remnant Of Gw170817, Shunke Ai, He Gao, Zi-Gao Dai, Xue-Feng Wu, Ang Li, Bing Zhang, Mu-Zi Li
Physics & Astronomy Faculty Research
Due to the limited sensitivity of the current gravitational wave (GW) detectors, the central remnant of the binary neutron star (NS) merger associated with GW170817 remains an open question. In view of the relatively large total mass, it is generally proposed that the merger of GW170817 would lead to a short-lived hypermassive NS or directly produce a black hole (BH). There is no clear evidence to support or rule out a long-lived NS as the merger remnant. Here, we utilize the GW and electromagnetic (EM) signals to comprehensively investigate the parameter space that allows a long-lived NS to survive as …
On The Radio Detectability Of Circumplanetary Discs, Zhaohuan Zhu, Sean M. Andrews, Andrea Isella
On The Radio Detectability Of Circumplanetary Discs, Zhaohuan Zhu, Sean M. Andrews, Andrea Isella
Physics & Astronomy Faculty Research
Discs around young planets, so-called circumplanetary discs (CPDs), are essential for planet growth, satellite formation, and planet detection. We study the millimetre and centimetre emission from accreting CPDs by using the simple α disc model. We find that it is easier to detect CPDs at shorter radio wavelengths (e.g. λ ≲ 1 mm). For example, if the system is 140 pc away from us, deep observations (e.g. 5 h) at ALMA Band 7 (0.87 mm) are sensitive to as small as 0.03 lunar mass of dust in CPDs. If the CPD is around a Jupiter mass planet 20 au away …
Grb 120729a: External Shock Origin For Both The Prompt Gamma-Ray Emission And Afterglow, Li-Ye Huang, Xiang-Gao Wang, Weikang Zheng, En-Wei Liang, Da-Bin Lin, Shi-Qing Zhong, Hai-Ming Zhang, Xiao-Li Huang, Alexi V. Filippenko, Bing Zhang
Grb 120729a: External Shock Origin For Both The Prompt Gamma-Ray Emission And Afterglow, Li-Ye Huang, Xiang-Gao Wang, Weikang Zheng, En-Wei Liang, Da-Bin Lin, Shi-Qing Zhong, Hai-Ming Zhang, Xiao-Li Huang, Alexi V. Filippenko, Bing Zhang
Physics & Astronomy Faculty Research
Gamma-ray burst (GRB) 120729A was detected by Swift/BAT and Fermi/GBM, and then rapidly observed by Swift/XRT, Swift/UVOT, and ground-based telescopes. It had a single long and smooth \gamma-ray emission pulse, which extends continuously to the X-rays. We report Lick/KAIT observations of the source, and make temporal and spectral joint fits of the multiwavelength light curves of GRB 120729A. It exhibits achromatic light-curve behavior, consistent with the predictions of the external shock model. The light curves are decomposed into four typical phases: onset bump (Phase I), normal decay (Phase II), shallow decay (Phase III), and post-jet break (Phase IV). The spectral …
Gamma-Ray Burst Jet Breaks Revisited, Xiang-Gao Wang, Bing Zhang, En-Wei Liang, Rui-Jing Liang, Da-Bin Lin, Jing Li, Long Li
Gamma-Ray Burst Jet Breaks Revisited, Xiang-Gao Wang, Bing Zhang, En-Wei Liang, Rui-Jing Liang, Da-Bin Lin, Jing Li, Long Li
Physics & Astronomy Faculty Research
Gamma-ray Burst (GRB) collimation has been inferred with the observations of achromatic steepening in GRB light curves, known as jet breaks. Identifying a jet break from a GRB afterglow light curve allows a measurement of the jet opening angle and true energetics of GRBs. In this paper, we re-investigate this problem using a large sample of GRBs that have an optical jet break that is consistent with being achromatic in the X-ray band. Our sample includes 99 GRBs from 1997 February to 2015 March that have optical and, for Swift GRBs, X-ray light curves that are consistent with the jet …
Planet-Driven Spiral Arms In Protoplanetary Disks. Ii. Implications, Jaehan Bae, Zhaohuan Zhu
Planet-Driven Spiral Arms In Protoplanetary Disks. Ii. Implications, Jaehan Bae, Zhaohuan Zhu
Physics & Astronomy Faculty Research
We examine whether various characteristics of planet-driven spiral arms can be used to constrain the masses of unseen planets and their positions within their disks. By carrying out two-dimensional hydrodynamic simulations varying planet mass and disk gas temperature, we find that a larger number of spiral arms form with a smaller planet mass and a lower disk temperature. A planet excites two or more spiral arms interior to its orbit for a range of disk temperatures characterized by the disk aspect ratio $0.04\leqslant {(h/r)}_{p}\leqslant 0.15$, whereas exterior to a planet's orbit multiple spiral arms can form only in cold disks …
Planet-Driven Spiral Arms In Protoplanetary Disks. I. Formation Mechanism, Jaehan Bae, Zhaohuan Zhu
Planet-Driven Spiral Arms In Protoplanetary Disks. I. Formation Mechanism, Jaehan Bae, Zhaohuan Zhu
Physics & Astronomy Faculty Research
Protoplanetary disk simulations show that a single planet can excite more than one spiral arm, possibly explaining the recent observations of multiple spiral arms in some systems. In this paper, we explain the mechanism by which a planet excites multiple spiral arms in a protoplanetary disk. Contrary to previous speculations, the formation of both primary and additional arms can be understood as a linear process when the planet mass is sufficiently small. A planet resonantly interacts with epicyclic oscillations in the disk, launching spiral wave modes around the Lindblad resonances. When a set of wave modes is in phase, they …
Planetary Candidates Observed By Kepler. Viii. A Fully Automated Catalog With Measured Completeness And Reliability Based On Data Release 25, Susan E. Thompson, Jeffrey L. Coughlin, Kelssey Hoffman, Fergal Mullally, Jessie L. Christiansen, Christopher J. Burke, Steve Bryson, Natalie Batalha, Michael R. Haas, Joseph Catanzarite, Jason F. Rowe, Geert Barentsen, Douglas A. Caldwell, Bruce D. Clarke, Jon M. Jenkins, Jie Li, David W. Latham, Jack J. Lissauer, Savita Mathur, Robert L. Morris, Shawn E. Seader, Jeffrey C. Smith, Todd C. Klaus, Joseph D. Twicken, Jeffrey E. Van Cleve, Bill Wohler, Rachel Akeson, David R. Ciardi, William D. Cochran, Christopher E. Henze, Steve B. Howell
Planetary Candidates Observed By Kepler. Viii. A Fully Automated Catalog With Measured Completeness And Reliability Based On Data Release 25, Susan E. Thompson, Jeffrey L. Coughlin, Kelssey Hoffman, Fergal Mullally, Jessie L. Christiansen, Christopher J. Burke, Steve Bryson, Natalie Batalha, Michael R. Haas, Joseph Catanzarite, Jason F. Rowe, Geert Barentsen, Douglas A. Caldwell, Bruce D. Clarke, Jon M. Jenkins, Jie Li, David W. Latham, Jack J. Lissauer, Savita Mathur, Robert L. Morris, Shawn E. Seader, Jeffrey C. Smith, Todd C. Klaus, Joseph D. Twicken, Jeffrey E. Van Cleve, Bill Wohler, Rachel Akeson, David R. Ciardi, William D. Cochran, Christopher E. Henze, Steve B. Howell
Physics & Astronomy Faculty Research
We present the Kepler Object of Interest (KOI) catalog of transiting exoplanets based on searching 4 yr of Kepler time series photometry (Data Release 25, Q1–Q17). The catalog contains 8054 KOIs, of which 4034 are planet candidates with periods between 0.25 and 632 days. Of these candidates, 219 are new, including two in multiplanet systems (KOI-82.06 and KOI-2926.05) and 10 high-reliability, terrestrial-size, habitable zone candidates. This catalog was created using a tool called the Robovetter, which automatically vets the DR25 threshold crossing events (TCEs). The Robovetter also vetted simulated data sets and measured how well it was able to separate …
On The Progenitors Of Type Ia Supernovae, Mario Livio, Paolo Mazzali
On The Progenitors Of Type Ia Supernovae, Mario Livio, Paolo Mazzali
Physics & Astronomy Faculty Research
We review all the models proposed for the progenitor systems of Type Ia supernovae and discuss the strengths and weaknesses of each scenario when confronted with observations. We show that all scenarios encounter at least a few serious difficulties, if taken to represent a comprehensive model for the progenitors of all Type Ia supernovae (SNe Ia). Consequently, we tentatively conclude that there is probably more than one channel leading SNe Ia. While the single-degenerate scenario (in which a single white dwarf accretes mass from a normal stellar companion) has been studied in some detail, the other scenarios will need a …
Frb 121102: A Repeatedly Combed Neutron Star By A Nearby Low-Luminosity Accreting Supermassive Black Hole, Bing Zhang
Frb 121102: A Repeatedly Combed Neutron Star By A Nearby Low-Luminosity Accreting Supermassive Black Hole, Bing Zhang
Physics & Astronomy Faculty Research
The origin of fast radio bursts (FRBs) remains mysterious. Recently, the only repeating FRB source, FRB 121102, was reported to possess an extremely large and variable rotation measure (RM). The inferred magnetic field strength in the burst environment is comparable to that in the vicinity of the supermassive black hole Sagittarius A* of our Galaxy. Here, we show that all of the observational properties of FRB 121102 (including the high RM and its evolution, the high linear polarization degree, an invariant polarization angle across each burst and other properties previously known) can be interpreted within the "cosmic comb" model, which …
Grb 130427a Afterglow: A Test For Grb Models, Massimiliano De Pasquale, M. J. Page, D. A. Kann, S. R. Oates, S. Schulze, Bing Zhang, Z. Cano, B. Gendre, D. Malesani, A. Rossi, N. Gehrels, E. Troja, L. Piro, M. Boër, G. Stratta
Grb 130427a Afterglow: A Test For Grb Models, Massimiliano De Pasquale, M. J. Page, D. A. Kann, S. R. Oates, S. Schulze, Bing Zhang, Z. Cano, B. Gendre, D. Malesani, A. Rossi, N. Gehrels, E. Troja, L. Piro, M. Boër, G. Stratta
Physics & Astronomy Faculty Research
Gamma-ray Burst 130427A had the largest fluence for almost 30 years. With an isotropic energy output of 8.5×1053 erg and redshift of 0.34, it combined a very high energy release with a relative proximity to Earth in an unprecedented fashion. Sensitive X-ray facilities such as {\it XMM-Newton} and {\it Chandra} detected the afterglow of this event for a record-breaking baseline of 90 Ms. We show the X-ray light curve of GRB 130427A of this event over such an interval. The light curve shows an unbroken power law decay with a slope of α=1.31 over more than three decades in time. …