• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
Prasanta Gorai, Bratati Bhat, Milan Sil, Suman K. Mondal, Rana Ghosh, Sandip K. Chakrabarti, and Ankan Das

After hydrogen, oxygen, and carbon, nitrogen is one of the most chemically active species in the interstellar medium. Nitrogen-bearing molecules are very important as they are actively involved in the formation of biomolecules. Therefore, it is essential to look for nitrogen-bearing species in various astrophysical sources, specifically around high-mass star-forming regions where the evolutionary history

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
Tomonari Michiyama, Daisuke Iono, Kouichiro Nakanishi, Junko Ueda, Toshiki Saito, Takuji Yamashita, Alberto Bolatto, and Min Yun

A galaxy–galaxy merger and the subsequent triggering of starburst activity are fundamental processes linked to the morphological transformation of galaxies and the evolution of star formation across the history of the universe. Both nuclear and disk-wide starbursts are assumed to occur during the merger process. However, quantifying both nuclear and disk-wide star formation activity is nontrivial because

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
David L. Nidever, Sten Hasselquist, Christian R. Hayes, Keith Hawkins, Joshua Povick, Steven R. Majewski, Verne V. Smith, Borja Anguiano, Guy S. Stringfellow, Jennifer S. Sobeck, Katia Cunha, Timothy C. Beers, Joachim M. Bestenlehner, Roger E. Cohen, D. A. Garcia-Hernandez, Henrik Jönsson, Christian Nitschelm, Matthew Shetrone, Ivan Lacerna, Carlos Allende Prieto, Rachael L. Beaton, Flavia Dell’Agli

We report the first APOGEE metallicities and α -element abundances measured for 3600 red giant stars spanning a large radial range of both the Large (LMC) and Small Magellanic Clouds, the largest Milky Way (MW) dwarf galaxies. Our sample is an order of magnitude larger than that of previous studies and extends to much larger radial distances. These are the first results presented that make use of the

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
Peter Bernath

A laboratory emission spectrum of TiO in the visible and near-infrared regions (476–1176 nm) has been calibrated and corrected. High-resolution experimental absorption cross sections for TiO with natural isotopic abundance are provided at a temperature of about 2300 K. These cross sections have been compared with those derived from the ExoMol line list. The experimental cross sections can be used directly

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
Dominik A. Riechers, Jacqueline A. Hodge, Riccardo Pavesi, Emanuele Daddi, Roberto Decarli, Rob J. Ivison, Chelsea E. Sharon, Ian Smail, Fabian Walter, Manuel Aravena, Peter L. Capak, Christopher L. Carilli, Pierre Cox, Elisabete da Cunha, Helmut Dannerbauer, Mark Dickinson, Roberto Neri, and Jeff Wagg

We report the detection of CO( J = 2 → 1) emission from three massive dusty starburst galaxies at z > 5 through molecular line scans in the NSF’s Karl G. Jansky Very Large Array (VLA) CO Luminosity Density at High Redshift (COLDz) survey. Redshifts for two of the sources, HDF 850.1 ( z = 5.183) and AzTEC-3 ( z = 5.298), were previously known. We revise a previous redshift estimate for the third source

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
Ramiz A. Qudsi, Riddhi Bandyopadhyay, Bennett A. Maruca, Tulasi N. Parashar, William H. Matthaeus, Alexandros Chasapis, S. Peter Gary, Barbara L. Giles, Daniel J. Gershman, Craig J. Pollock, Robert J. Strangeway, Roy B. Torbert, Thomas E. Moore, and James L. Burch

Weakly collisional space plasmas are rarely in local thermal equilibrium and often exhibit non-Maxwellian electron and ion velocity distributions that lead to the growth of microinstabilities—that is, enhanced electric and magnetic fields at relatively short wavelengths. These instabilities play an active role in the evolution of space plasmas, as does ubiquitous broadband turbulence induced by turbulent

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
Masayuki Yamaguchi, Kazunori Akiyama, Takashi Tsukagoshi, Takayuki Muto, Akimasa Kataoka, Fumie Tazaki, Shiro Ikeda, Misato Fukagawa, Mareki Honma, and Ryohei Kawabe

With an emphasis on improving the fidelity even in super-resolution regimes, new imaging techniques have been intensively developed over the last several years, which may provide substantial improvements to the interferometric observation of protoplanetary disks. In this study, sparse modeling (SpM) is applied for the first time to observational data sets taken by the Atacama Large Millimeter/submillimeter

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
Gregory S. Vance, Patrick A. Young, Christopher L. Fryer, and Carola I. Ellinger

Mixing above the proto-neutron star is believed to play an important role in the supernova engine, and this mixing results in a supernova explosion with asymmetries. Elements produced in the innermost ejecta, e.g., 56 Ni and 44 Ti, provide a clean probe of this engine. The production of 44 Ti is particularly sensitive to the exact production pathway and, by understanding the available pathways, we

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
M. Orio, J. J. Drake, J.-U. Ness, E. Behar, G. J. M. Luna, M. J. Darnley, J. Gallagher, R. D. Gehrz, N. P. M. Kuin, J. Mikolajewska, N. Ospina, K. L. Page, R. Poggiani, S. Starrfield, R. Williams, and C. E. Woodward

The recurrent nova (RN) V3890 Sgr was observed during the seventh day after the onset of its most recent outburst, with the Chandra ACIS-S camera and High Energy Transmission Gratings. A rich emission line spectrum was detected, due to transitions of Fe-L and K-shell ions ranging from neon to iron. The measured absorbed flux is ≈10 −10 erg cm −2 s −1 in the 1.4–15 Å range (0.77–8.86 keV). The line

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
Jennifer Wojno, Karoline M. Gilbert, Evan N. Kirby, Ivanna Escala, Rachael L. Beaton, Erik J. Tollerud, Steven R. Majewski, and Puragra Guhathakurta

We present chemical abundances of red giant branch (RGB) stars in the dwarf spheroidal (dSph) satellite system of Andromeda (M31), using spectral synthesis of medium-resolution ( R ∼ 6000) spectra obtained with the Keck II telescope and Deep Imaging Multi-Object Spectrometer spectrograph via the Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo survey. We coadd stars according to

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
Jérémy Bourgalais, Nathalie Carrasco, Quentin Changeat, Olivia Venot, Lora Jovanović, Pascal Pernot, Jonathan Tennyson, Katy L. Chubb, Sergey N. Yurchenko, and Giovanna Tinetti

With the upcoming launch of space telescopes dedicated to the study of exoplanets, the Atmospheric Remote-Sensing Infrared Exoplanet Large-survey (ARIEL) and the James Webb Space Telescope (JWST), a new era is opening in exoplanetary atmospheric explorations. However, especially in relatively cold planets around later-type stars, photochemical hazes and clouds may mask the composition of the lower

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-27
S. Nulsen, R. Kraft, G. Germain, W. Dunn, G. Tremblay, L. Beegle, G. Branduardi-Raymont, E. Bulbul, R. Elsner, R. Hodyss, and S. Vance

We analyze archival Chandra X-ray Observatory observations of Jupiter to search for emission from the Galilean moons. X-ray emission has previously been reported from Io and Europa using a subset of these data. We confirm this detection, and marginally detect X-ray emission from both Ganymede and Callisto as well. The X-ray spectrum of Europa is strongly peaked around the neutral oxygen fluorescence

更新日期：2020-05-27
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-26
Bruce G. Elmegreen and Debra Meloy Elmegreen

To study the vertical distribution of the earliest stages of star formation in galaxies, three edge-on spirals, NGC 891, NGC 3628, and IC 5052, observed by the Spitzer Space Telescope InfraRed Array Camera (IRAC) were examined for compact 8 μ m cores using an unsharp mask technique; 173, 267, and 60 cores were distinguished, respectively. Color–color distributions suggest a mixture of polycyclic aromatic

更新日期：2020-05-26
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-26
Ivan N. Sharykin and Alexander G. Kosovichev

The paper presents results of a search for helioseismic events (sunquakes) produced by M-X class solar flares during Solar Cycle 24. The search is performed by analyzing photospheric Dopplergrams from the Helioseismic Magnetic Imager. Among the total number of 500 M-X class flares, 94 helioseismic events were detected. Our analysis has shown that many strong sunquakes were produced by solar flares

更新日期：2020-05-26
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-26
Sumner Starrfield, Maitrayee Bose, Christian Iliadis, W. Raphael Hix, Charles E. Woodward, and R. Mark Wagner

We report on studies of classical nova (CN) explosions where we follow the evolution of thermonuclear runaways (TNRs) on carbon–oxygen (CO) white dwarfs (WDs). We vary both the mass of the WD (from 0.6 M ⊙ to 1.35 M ⊙ ) and the composition of the accreted material. Our simulations are guided by the results of multidimensional studies of TNRs in WDs, which find that sufficient mixing with WD core material

更新日期：2020-05-26
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-26
N. J. Riley, H. J. Quevedo, Roger D. Bengtson, T. Ditmire, M. Kimmel, C. S. Speas, and J. L. Porter

We report experimental results on the stability of a magnetized laser-launched blast wave scaled to simulate a late-stage supernova remnant. We extend previous results to show the effect of a dynamically significant magnetic field on the spatial mode spectrum of the instability. We find that magnetic fields reduce instability growth, possibly influencing turbulent feedback to the interstellar medium

更新日期：2020-05-26
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-26
Nathen H. Nguyen, Paulina Lira, Benny Trakhtenbrot, Hagai Netzer, Claudia Cicone, Roberto Maiolino, and Ohad Shemmer

We present ALMA Band 7 data of the [C ii] ##IMG## [http://ej.iop.org/images/0004-637X/895/1/74/apjab8bd3ieqn1.gif] {$\lambda 157.74\,\mu {\rm{m}}$} emission line and underlying far-IR (FIR) continuum for 12 luminous quasars at ##IMG## [http://ej.iop.org/images/0004-637X/895/1/74/apjab8bd3ieqn2.gif] {$z\simeq 4.8$} powered by fast-growing supermassive black holes (SMBHs). Our total sample consists of

更新日期：2020-05-26
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-26
Seiji Kameno, Satoko Sawada-Satoh, C. M. Violette Impellizzeri, Daniel Espada, Naomasa Nakai, Hajime Sugai, Yuichi Terashima, Kotaro Kohno, Minju Lee, and Sergio Martín

We report ALMA observations of NGC 1052 to search for mass accretion in a gas-poor active galactic nucleus. We detected CO emission representing a rotating ring-like circumnuclear disk (CND) seen edge-on with a gas mass of 5.3 × 10 5 M ⊙ . The CND has smaller gas mass than that in typical Seyfert galaxies with circumnuclear star formation and is too gas-poor to drive mass accretion onto the central

更新日期：2020-05-26
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-26
Uri Keshet, Ido Reiss, and Guillaume Hurier

Virial shocks around galaxy clusters are expected to show a cutoff in the thermal Sunyaev–Zel’dovich (SZ) signal, coincident with a leptonic ring. However, until now, leptonic virial signals have only been reported in Coma and in stacked Fermi Large Area Telescope (LAT) clusters, and an SZ virial shock signal reported only in A2319. We point out that a few clusters—presently Coma, A2319, and A2142—already

更新日期：2020-05-26
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-26
A. T. Bajkova, G. Carraro, V. I Korchagin, N. O. Budanova, and V. V. Bobylev

We employ Gaia DR2 proper motions for 151 Milky Way globular clusters (GCs) from Vasiliev in tandem with distances and line-of-sight velocities to derive their kinematical properties. To assign clusters to the Milky Way thick disk, bulge, and halo, we follow the approach of Posti et al., who distinguished among different Galactic stellar components using stars’ orbits. In particular, we use the ratio

更新日期：2020-05-26
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
B. P. Gompertz, A. J. Levan, and N. R. Tanvir

Short gamma-ray bursts (SGRBs) are now known to be the product of the merger of two compact objects. However, two possible formation channels exist: neutron star–neutron star (NS–NS) or NS–black hole (BH). The landmark SGRB 170817A provided evidence for the NS–NS channel, thanks to analysis of its gravitational wave signal. We investigate the complete population of SGRBs with an associated redshift

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
J. Armijos-Abendaño, J. Martín-Pintado, E. López, M. Llerena, N. Harada, M. A. Requena-Torres, S. Martín, V. M. Rivilla, D. Riquelme, and F. Aldas

The lines of HOC + , HCO, and CO + are considered good tracers of photon-dominated regions (PDRs) and X-ray-dominated regions. We study these tracers toward regions of the Sgr B2 cloud selected to be affected by different heating mechanisms. We find the lowest values of the column density ratios of HCO + versus HOC + , HCO, and CO + in dense H ii gas, where UV photons dominate the heating and chemistry

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Tanmoy Laskar, Charles L. H. Hull, and Paulo Cortes

Polarization measurements of gamma-ray burst (GRB) afterglows are a promising means of probing the structure, geometry, and magnetic composition of relativistic GRB jets. However, a precise treatment of instrumental calibration is vital for a robust physical interpretation of polarization data, requiring tests of and validations against potential instrumental systematics. We illustrate this with Atacama

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
G. A. Rodríguez Castillo, G. L. Israel, A. Belfiore, F. Bernardini, P. Esposito, F. Pintore, A. De Luca, A. Papitto, L. Stella, A. Tiengo, L. Zampieri, M. Bachetti, M. Brightman, P. Casella, D. D’Agostino, S. Dall’Osso, H. P. Earnshaw, F. Fürst, F. Haberl, F. A. Harrison, M. Mapelli, M. Marelli, M. Middleton, C. Pinto, T. P. Roberts, R. Salvaterra, R. Turolla, D. J. Walton, and A. Wolter

We discovered 2.8 s pulsations in the X-ray emission of the ultraluminous X-ray source (ULX) M51 ULX-7 within the UNSEeN project, which was designed to hunt for new pulsating ULXs (PULXs) with XMM-Newton. The pulse shape is sinusoidal, and large variations of its amplitude were observed even within single exposures (pulsed fraction from less than 5% to 20%). Source M51 ULX-7 is variable, generally

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Zhi-Qiu Huang, Ruo-Yu Liu, Jagdish C. Joshi, and Xiang-Yu Wang

Measurements of cosmic-ray (CR) positron fractions by PAMELA and other experiments have found an excess above 10 GeV relative to the standard predictions for secondary production in the interstellar medium. Although the excess has been mainly suggested to arise from some primary sources of positrons (such as pulsars and or annihilating dark matter particles), the almost constant flux ratio of ##IMG##

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Joey S. G. Mombarg, Aaron Dotter, Timothy Van Reeth, Andrew Tkachenko, Sarah Gebruers, and Conny Aerts

It has been known for several decades that transport of chemical elements is induced by the process of microscopic atomic diffusion. Yet the effect of atomic diffusion, including radiative levitation, has hardly been studied in the context of gravity-mode pulsations of core hydrogen burning stars. In this paper we study the difference in the properties of such modes for models with and without atomic

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Lorenzo Spina, Thomas Nordlander, Andrew R. Casey, Megan Bedell, Valentina D’Orazi, Jorge Meléndez, Amanda I. Karakas, Silvano Desidera, Martina Baratella, Jhon J. Yana Galarza, and Giada Casali

Magnetic fields and stellar spots can alter the equivalent widths of absorption lines in stellar spectra, varying during the activity cycle. This also influences the information that we derive through spectroscopic analysis. In this study, we analyze high-resolution spectra of 211 sunlike stars observed at different phases of their activity cycles, in order to investigate how stellar activity affects

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
David Nesvorný, Andrew N. Youdin, Raphael Marschall, and Derek C. Richardson

For problems in astrophysics, planetary science, and beyond, numerical simulations are often limited to simulating fewer particles than in the real system. To model collisions, the simulated particles (a.k.a. superparticles) need to be inflated to represent a collectively large collisional cross section of real particles. Here we develop a superparticle-based method that replicates the kinetic energy

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Caius L. Selhorst, Cassio L. Barbosa, Paulo J. A. Simões, Aline A. Vidotto, and Adriana Valio

When a planet transits in front of its host star, a fraction of its light is blocked, decreasing the observed flux from the star. The same is expected to occur when observing the stellar radio flux. However, at radio wavelengths, the planet also radiates, depending on its temperature, and thus modifies the transit depths. We explore this scenario simulating the radio lightcurves of transits of hot

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Michael Gedalin

In situ measurements at heliospheric shocks show that inside the shock front large-scale electric and magnetic fields are accompanied with strong small-scale fields. Until recently, it was widely believed that particle dynamics is determined by the large-scale fields. During the last several years, claims have been made that the small-scale fields are of primary importance. Here we show that the large-scale

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
H. Tilquin, J. P. Eastwood, and T. D. Phan

Reconnecting current sheets in the solar wind play an important role in the dynamics of the heliosphere and offer an opportunity to study magnetic reconnection exhausts under a wide variety of inflow and magnetic shear conditions. However, progress in understanding reconnection can be frustrated by the difficulty of finding events in long time-series data. Here we describe a new method to detect magnetic

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
John T. Stefan and Alexander G. Kosovichev

Sunquakes are one of the more distinct secondary phenomena related to solar flares, where energy deposition in the lower layers of the Sun’s atmosphere excites acoustic waves easily visible in photospheric dopplergrams. We explore two possible excitation mechanisms of sunquakes in the context of the electron beam hypothesis: an instantaneous transfer of momentum and a gradual applied force due to flare

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Anna Y. Q. Ho, Daniel A. Perley, S. R. Kulkarni, Dillon Z. J. Dong, Kishalay De, Poonam Chandra, Igor Andreoni, Eric C. Bellm, Kevin B. Burdge, Michael Coughlin, Richard Dekany, Michael Feeney, Dmitry D. Frederiks, Christoffer Fremling, V. Zach Golkhou, Matthew J. Graham, David Hale, George Helou, Assaf Horesh, Mansi M. Kasliwal, Russ R. Laher, Frank J. Masci, A. A. Miller, Michael Porter, Anna Ridnaia

We present ZTF18abvkwla (the “Koala”), a fast blue optical transient discovered in the Zwicky Transient Facility (ZTF) One-Day Cadence (1DC) Survey. ZTF18abvkwla has a number of features in common with the groundbreaking transient AT 2018cow: blue colors at peak ( ##IMG## [http://ej.iop.org/images/0004-637X/895/1/49/apjab8bcfieqn1.gif] {$g-r\approx -0.5$} mag), a short rise time from half-max of under

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
M. Cadelano, S. Saracino, E. Dalessandro, F. R. Ferraro, B. Lanzoni, D. Massari, C. Pallanca, and M. Salaris

We used a set of moderately deep and high-resolution optical observations obtained with the Hubble Space Telescope to investigate the properties of the stellar population in the heavily obscured bulge globular cluster (GC) NGC 6256. The analysis of the color–magnitude diagram (CMD) revealed a stellar population with an extended blue horizontal branch severely affected by differential reddening, which

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Naoki Yamamoto and Di-Lun Yang

We construct the chiral radiation transport equation for left-handed neutrinos in the context of radiation hydrodynamics for core-collapse supernovae. Based on the chiral kinetic theory incorporating quantum corrections due to the chirality of fermions, we derive a general relativistic form of the chiral transfer equation with collisions. We show that such quantum corrections explicitly break the spherical

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
C. R. Sangeetha, Durgesh Tripathi, and S. P. Rajaguru

We perform a study of fluid motions and its temporal evolution in and around a small bipolar emerging flux region using observations made by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. We employ local correlation tracking of the Doppler observations to follow horizontal fluid motions and line-of-sight magnetograms to follow the flux emergence. Changes in vertical vorticity

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Shafqat Riaz, Dimitry Ayzenberg, Cosimo Bambi, and Sourabh Nampalliwar

X-ray reflection spectroscopy (or iron line method) is a powerful tool to probe the strong gravity region of black holes, and currently is the only technique for measuring the spin of the supermassive ones. While all the available relativistic reflection models assume thin accretion disks, we know that several sources accrete near or above the Eddington limit and therefore must have thick accretion

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Deepakshi Madaan, Sophia Lianou, and Shantanu Basu

A determination of the mass function (MF) of stellar clusters can be quite dependent on the range of measured masses, the fitting technique, and the analytic function that is being fit to the data. Here, we use Hubble Space Telescope/WFPC2 data of NGC 1711, a stellar cluster in the Large Magellanic Cloud, as a test case to explore a range of possible determinations of the MF from a single data set

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Laura A. Hayes, Andrew R. Inglis, Steven Christe, Brian Dennis, and Peter T. Gallagher

Small-amplitude quasi-periodic pulsations (QPPs) detected in soft X-ray emission are commonplace in many flares. To date, the underpinning processes resulting in the QPPs are unknown. In this paper, we attempt to constrain the prevalence of stationary QPPs in the largest statistical study to date, including a study of the relationship of QPP periods to the properties of the flaring active region, flare

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-25
Kyuhyoun Cho, Jongchul Chae, Ryun-Young Kwon, Su-Chan Bong, and Kyung-Suk Cho

Solar rotational tomography (SRT) is an important method to reconstruct the physical parameters of the three-dimensional solar corona. Here we propose an approach to apply the filtered backprojection (FBP) algorithm to the SRT. The FBP algorithm is generally not suitable for SRT due to the several issues with solar extreme ultraviolet (EUV) observations—in particular, a problem caused by missing data

更新日期：2020-05-25
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
Kyoung-Sun Lee, Hirohisa Hara, Kyoko Watanabe, Anand D. Joshi, David H. Brooks, Shinsuke Imada, Avijeet Prasad, Phillip Dang, Toshifumi Shimizu, Sabrina L. Savage, Ronald Moore, Navdeep K. Panesar, and Jeffrey W. Reep

We have investigated an M1.3 limb flare, which develops as a magnetic loop/arch that fans out from an X-ray jet. Using Hinode/EIS, we found that the temperature increases with height to a value of over 10 7 K at the loop top during the flare. The measured Doppler velocity (redshifts of 100–500 km s −1 ) and the nonthermal velocity (≥100 km s −1 ) from Fe xxiv also increase with loop height. The electron

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
Julián D. Alvarado-Gómez, Jeremy J. Drake, Federico Fraschetti, Cecilia Garraffo, Ofer Cohen, Christian Vocks, Katja Poppenhäger, Sofia P. Moschou, Rakesh K. Yadav, and Ward B. Manchester IV

Coronal mass ejections (CMEs) on stars other than the Sun have proven very difficult to detect. One promising pathway lies in the detection of type II radio bursts. Their appearance and distinctive properties are associated with the development of an outward propagating CME-driven shock. However, dedicated radio searches have not been able to identify these transient features in other stars. Large

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
Jie Lin, Rui-Jing Lu, Da-Bin Lin, and Xiang-Gao Wang

Ultra-long-duration gamma-ray burst GRB 111209A was found to be associated with a very luminous supernovae (SNe) SN 2011kl. The physics of GRB 111209A/SN 2011kl has been extensively studied in the literature, but such research has not yet settled down. By investigating in detail the characteristics of the X-ray light curve of GRB 111209A, coupled with the temporal and spectral features observed in

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
A. Goldstein, C. Fletcher, P. Veres, M. S. Briggs, W. H. Cleveland, M. H. Gibby, C. M. Hui, E. Bissaldi, E. Burns, R. Hamburg, A. von Kienlin, D. Kocevski, B. Mailyan, C. Malacaria, W. S. Paciesas, O. J. Roberts, and C. A. Wilson-Hodge

The capability of the Fermi Gamma-ray Burst Monitor (GBM) to localize gamma-ray bursts (GRBs) is evaluated for two different automated algorithms: the GBM Team’s RoboBA algorithm and the independently developed BALROG algorithm. Through a systematic study utilizing over 500 GRBs with known locations from instruments like Swift and the Fermi Large Area Telescope, we directly compare the effectiveness

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
Kundan Kadam, Eduard Vorobyov, Zsolt Regály, Ágnes Kóspál, and Péter Ábrahám

While accreting through a circumstellar disk, young stellar objects are observed to undergo sudden and powerful accretion events known as FUor or EXor outbursts. Although such episodic accretion is considered to be an integral part of the star formation process, the triggers and mechanisms behind them remain uncertain. We conducted global numerical hydrodynamics simulations of protoplanetary disk formation

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
K. A. Bostroem, S. Valenti, D. J. Sand, J. E. Andrews, S. D. Van Dyk, L. Galbany, D. Pooley, R. C. Amaro, N. Smith, S. Yang, G. C. Anupama, I. Arcavi, E. Baron, P. J. Brown, J. Burke, R. Cartier, D. Hiramatsu, R. Dastidar, J. M. DerKacy, Y. Dong, E. Egami, S. Ertel, A. V. Filippenko, O. D. Fox, J. Haislip, G. Hosseinzadeh, D. A. Howell, A. Gangopadhyay, S. W. Jha, V. Kouprianov, B. Kumar, M. Lundquist

We present the discovery and high-cadence follow-up observations of SN 2018ivc, an unusual SNe II that exploded in NGC 1068 ( D = 10.1 Mpc). The light curve of SN 2018ivc declines piecewise-linearly, changing slope frequently, with four clear slope changes in the first 30 days of evolution. This rapidly changing light curve indicates that interaction between the circumstellar material and ejecta plays

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
Evan E. Schneider, Eve C. Ostriker, Brant E. Robertson, and Todd A. Thompson

We present the fourth simulation of the Cholla Galactic OutfLow Simulations suite. Using a physically motivated prescription for clustered supernova feedback, we successfully drive a multiphase outflow from a disk galaxy. The high resolution (<5 pc) across a relatively large domain (20 kpc) allows us to capture the hydrodynamic mixing and dynamical interactions between the hot and cool ( T ∼ 10 4 K)

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
C. A. Kierans, S. E. Boggs, A. Zoglauer, A. W. Lowell, C. Sleator, J. Beechert, T. J. Brandt, P. Jean, H. Lazar, J. Roberts, T. Siegert, J. A. Tomsick, and P. von Ballmoos

The signature of positron annihilation, namely the 511 keV γ -ray line, was first detected coming from the direction of the Galactic center in the 1970s, but the source of Galactic positrons still remains a puzzle. The measured flux of the annihilation corresponds to an intense steady source of positron production, with an annihilation rate on the order of ∼10 43 ##IMG## [http://ej.iop.org/images/

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
R. M. Ludlam, E. M. Cackett, J. A. García, J. M. Miller, P. M. Bult, T. E. Strohmayer, S. Guillot, G. K. Jaisawal, C. Malacaria, A. C. Fabian, and C. B. Markwardt

We report on the first simultaneous Neutron Star Interior Composition Explore (NICER) and Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the neutron star (NS) low-mass X-ray binary 4U 1735−44, obtained in 2018 August. The source was at a luminosity of ∼1.8 ( D /5.6 kpc) 2 × 10 37 erg s −1 in the 0.4–30 keV band. We account for the continuum emission with two different continuum descriptions

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
Sean D. Brittain, Joan R. Najita, Ruobing Dong, and Zhaohuan Zhu

The high occurrence rates of spiral arms and large central clearings in protoplanetary disks, if interpreted as signposts of giant planets, indicate that gas giants commonly form as companions to young stars ( 10 Myr) have yielded few successes. This discrepancy could be explained if most giant planets form by “cold start,” i.e., by radiating away much of their formation energy as they assemble their

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
Brandon S. Hensley and B. T. Draine

The sight line toward the luminous blue hypergiant Cyg OB2-12 is widely used to study interstellar dust on account of its large extinction ( A V ≃ 10 mag) and the fact that this extinction appears to be dominated by dust typical of the diffuse interstellar medium. We present a new analysis of archival Infrared Space Observatory Short Wavelength Spectrometer and Spitzer IRS observations of Cyg OB2-12

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
A. Panaitescu

We derive basic analytical results for the timing and decay of the gamma-ray burst (GRB) counterpart and delayed afterglow light curves for a brief emission episode from a relativistic surface endowed with angular structure, consisting of a uniform core of size ##IMG## [http://ej.iop.org/images/0004-637X/895/1/39/apjab8bdfieqn1.gif] {${\theta }_{c}$} (Lorentz factor ##IMG## [http://ej.iop.org/imag

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-21
J. N. Reeves, V. Braito, G. Chartas, F. Hamann, S. Laha, and E. Nardini

Past X-ray observations of the nearby luminous quasar PDS 456 (at z = 0.184) have revealed a wide-angle accretion disk wind with an outflow velocity of ∼−0.25 c , as observed through observations of its blueshifted iron K-shell absorption line profile. Here we present three new XMM-Newton observations of PDS 456: one in 2018 September where the quasar was bright and featureless and two in 2019 September

更新日期：2020-05-21
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-19
Arman Tursunov, Zdeněk Stuchlík, Martin Kološ, Naresh Dadhich, and Bobomurat Ahmedov

The production and acceleration mechanisms of ultrahigh-energy cosmic rays (UHECRs) of energy >10 20 eV, clearly beyond the GZK cutoff limit, remain unclear, which points to the exotic nature of the phenomena. Recent observations of extragalactic neutrinos may indicate that the source of UHECRs is an extragalactic supermassive black hole (SMBH). We demonstrate that ultraefficient energy extraction

更新日期：2020-05-19
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-19
Yang Gao, Lei Qian, and Di Li

The magnetic fields of exoplanets shield the planets from cosmic rays and interplanetary plasma. Due to the interaction with the electrons from their host stars, the exoplanetary magnetospheres are predicted to have both cyclotron and synchrotron radio emissions, neither of which have been definitively identified in observations. As the coherent cyclotron emission has been extensively studied in the

更新日期：2020-05-19
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-19
Hefan Li, Cuihua Du, Yanbin Yang, Heidi Jo Newberg, Jun Ma, Jianrong Shi, and Yunsong Piao

We use the second Gaia data release (Gaia DR2), combined with Radial Velocity Experiment spectroscopic surveys, to identify the substructures in the nearby stellar halo. We select 3845 halo stars kinematically and chemically and determine their density distribution in energy and angular momentum space. To select the substructures from overdensities, we reshuffle the velocities and estimate their significance

更新日期：2020-05-19
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-19
Stephanie L. Olson, Malte Jansen, and Dorian S. Abbot

Liquid water oceans are at the center of our search for life on exoplanets because water is a strict requirement for life as we know it. However, oceans are dynamic habitats—and some oceans may be better hosts for life than others. In Earth’s ocean, circulation transports essential nutrients such as phosphate and is a first-order control on the distribution and productivity of life. Of particular importance

更新日期：2020-05-19
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-19
Daniel DeFelippis, Shy Genel, Greg L. Bryan, Dylan Nelson, Annalisa Pillepich, and Lars Hernquist

We present an analysis of the angular momentum content of the circumgalactic medium (CGM) using TNG100, one of the flagship runs of the IllustrisTNG project. We focus on Milky Way–mass halos (∼10 12 M ⊙ ) at z = 0 but also analyze other masses and redshifts up to z = 5. We find that the CGM angular momentum properties are strongly correlated with the stellar angular momentum of the corresponding galaxy:

更新日期：2020-05-19
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-19
Silvia Raso, Mattia Libralato, Andrea Bellini, Francesco R. Ferraro, Barbara Lanzoni, Mario Cadelano, Cristina Pallanca, Emanuele Dalessandro, Giampaolo Piotto, Jay Anderson, and Sangmo Tony Sohn

We constructed a Hubble Space Telescope (HST) astrophotometric catalog of the central region of the Galactic globular cluster NGC 1261. This catalog, complemented with Gaia DR2 data sampling the external regions, has been used to estimate the structural parameters of the system (i.e., core, half-mass, tidal radii, and concentration) from its resolved star density profile. We computed high-precision

更新日期：2020-05-19
• Astrophys. J.  (IF 5.58) Pub Date : 2020-05-19
Nia Imara, Ilse De Looze, Christopher M. Faesi, and Diane Cormier

We present the highest-resolution (1″) 12 CO observations of molecular gas in the dwarf starburst galaxy NGC 625 to date, obtained with Atacama Large Millimeter/submillimeter Array. The molecular gas, which is distributed in discrete clouds within an area of 0.4 kpc 2 , does not have well-ordered large-scale motions. We measure a molecular mass in NGC 625 of 5.3 × 10 6 ##IMG## [http://ej.iop.org/i

更新日期：2020-05-19
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