adsabs/SciX_UAT_keywords huggingface dataset:
Global MHD Simulations of the Time-dependent Corona

We describe, test, and apply a technique to incorporate full-Sun, surface flux evolution into an MHD model of the global solar corona. Requiring only maps of the evolving surface flux, our method is similar to that of Lionello et al., but we introduce two ways to correct the electric field at the lower boundary to mitigate spurious currents. We verify the accuracy of our procedures by comparing to a reference simulation, driven with known flows and electric fields. We then present a thermodynamic MHD calculation lasting one solar rotation driven by maps from the magnetic flux evolution model of Schrijver & DeRosa. The dynamic, time-dependent nature of the model corona is illustrated by examining the evolution of the open flux boundaries and forward-modeled EUV emission, which evolve in response to surface flows and the emergence and cancellation flux. Although our main goal is to present the method, we briefly investigate the relevance of this evolution to properties of the slow solar wind, examining the mapping of dipped field lines to the topological signatures of the "S-Web" and comparing charge state ratios computed in the time-dependently driven run to a steady-state equivalent. Interestingly, we find that driving on its own does not significantly improve the charge state ratios, at least in this modest resolution run that injects minimal helicity. Still, many aspects of the time-dependently driven model cannot be captured with traditional steady-state methods, and such a technique may be particularly relevant for the next generation of solar wind and coronal mass ejection models.

Keywords: magnetohydrodynamical simulations; solar corona
Optical and Near-infrared Observations of the Nearby SN Ia 2017cbv

Supernova (SN) 2017cbv in NGC 5643 is one of a handful of Type Ia supernovae (SNe Ia) reported to have excess blue emission at early times. This paper presents extensive BVRIYJHKs-band light curves of SN 2017cbv, covering the phase from -16 to +125 days relative to B-band maximum light. The SN 2017cbv reached a B-band maximum of 11.710 ± 0.006 mag, with a postmaximum magnitude decline of Δm15(B) = 0.990 ± 0.013 mag. The SN suffered no host reddening based on Phillips intrinsic color, the Lira-Phillips relation, and the CMAGIC diagram. By employing the CMAGIC distance modulus μ = 30.58 ± 0.05 mag and assuming H0 = 72 km s-1 Mpc-1, we found that 0.73 M⊙ 56Ni was synthesized during the explosion of SN 2017cbv, which is consistent with estimates using reddening- and distance-free methods via the phases of the secondary maximum of the near-IR- (NIR-) band light curves. We also present 14 NIR spectra from -18 to +49 days relative to the B-band maximum light, providing constraints on the amount of swept-up hydrogen from the companion star in the context of the single degenerate progenitor scenario. No Paβ emission feature was detected from our postmaximum NIR spectra, placing a hydrogen mass upper limit of 0.1 M⊙. The overall optical/NIR photometric and NIR spectral evolution of SN 2017cbv is similar to that of a normal SN Ia, even though its early evolution is marked by a flux excess not seen in most other well-observed normal SNe Ia. We also compare the exquisite light curves of SN 2017cbv with some Mch delayed detonation models and sub-Mch double detonation models.

Keywords: type ia supernovae
A Type II Radio Burst Driven by a Blowout Jet on the Sun

Type II radio bursts are often associated with coronal shocks that are typically driven by coronal mass ejections (CMEs) from the Sun. Here we conduct a case study of a type II radio burst that is associated with a C4.5-class flare and a blowout jet, but without the presence of a CME. The blowout jet is observed near the solar disk center in the extreme-ultraviolet (EUV) passbands with different characteristic temperatures. Its evolution involves an initial phase and an ejection phase with a velocity of 560 ± 87 km s-1. Ahead of the jet front, an EUV wave propagates at a projected velocity of ~403 ± 84 km s-1 in the initial stage. The velocity of the type II radio burst is estimated to be ~641 km s-1, which corresponds to the shock velocity against the coronal density gradient. The EUV wave and the type II radio burst are closely related to the ejection of the blowout jet, suggesting that both are likely the manifestation of a coronal shock driven by the ejection of the blowout jet. The type II radio burst likely starts lower than those associated with CMEs. The combination of the velocities of the radio burst and the EUV wave yields a modified shock velocity at ~757 km s-1. The Alfvén Mach number is in the range of 1.09-1.18, implying that the shock velocity is 10%-20% larger than the local Alfvén velocity.

Keywords: solar coronal radio emission; solar filament eruptions; shocks; solar coronal waves; solar activity
Nobeyama Survey of Inward Motions toward Cores in Orion Identified by SCUBA-2

In this study, 36 cores (30 starless and six protostellar) identified in Orion were surveyed to search for inward motions. We used the Nobeyama 45 m radio telescope, and mapped the cores in the J = 1 → 0 transitions of HCO+, H13CO+, N2H+, HNC, and HN13C. The asymmetry parameter δV, which was the ratio of the difference between the HCO+ and H13CO+ peak velocities to the H13CO+ line width, was biased toward negative values, suggesting that inward motions were more dominant than outward motions. Three starless cores (10% of all starless cores surveyed) were identified as cores with blue-skewed line profiles (asymmetric profiles with more intense blueshifted emission), and another two starless cores (7%) were identified as candidate blue-skewed line profiles. The peak velocity difference between HCO+ and H13CO+ of them was up to 0.9 km s-1, suggesting that some inward motions exceeded the speed of sound for the quiescent gas (~10-17 K). The mean of δV of the five aforementioned starless cores was derived to be -0.5 ± 0.3. One core, G211.16-19.33North3, observed using the Atacama Compact Array of the Atacama Large Millimeter/submillimeter Array in DCO+ J = 3 → 2 exhibited blue-skewed features. Velocity offset in the blue-skewed line profile with a dip in the DCO+ J = 3 → 2 line was larger (~0.5 km s-1) than that in HCO+ J = 1 → 0 (~0.2 km s-1), which may represent gravitational acceleration of inward motions. It seems that this core is at the last stage in the starless phase, judging from the chemical evolution factor version 2.0 (CEF2.0).

Keywords: star formation; star forming regions; interstellar medium; interstellar line emission; interstellar clouds; collapsing clouds
Plasmoids, Flows, and Jets during Magnetic Reconnection in a Failed Solar Eruption

We report a detailed analysis of a failed eruption and flare in active region 12018 on 2014 April 3 using multiwavelength observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly, IRIS, STEREO, and Hinode/Solar Optical Telescope. At least four jets were observed to emanate from the cusp of this small active region (large bright point) with a null-point topology during the 2 hr prior to the slow rise of a filament. During the filament slow rise multiple plasma blobs were seen, most likely formed in a null-point current sheet near the cusp. The subsequent filament eruption, which was outside the IRIS field of view, was accompanied by a flare but remained confined. During the explosive flare reconnection phase, additional blobs appeared repetitively and moved bidirectionally within the flaring region below the erupting filament. The filament kinked, rotated, and underwent leg-leg reconnection as it rose, yet it failed to produce a coronal mass ejection. Tiny jet-like features in the fan loops were detected during the filament slow rise/preflare phase. We interpret them as signatures of reconnection between the ambient magnetic field and the plasmoids leaving the null-point sheet and streaming along the fan loops. We contrast our interpretation of these tiny jets, which occur within the large-scale context of a failed filament eruption, with the local nanoflare-heating scenario proposed by Antolin et al.

Keywords: solar magnetic reconnection; solar flares; solar filament eruptions; plasma jets
Uncertainty Propagation in (Gaussian) Convolution

Convolution of spectra, maps, or even higher dimensional data is often part of data reduction or analysis. Often a Gaussian kernel is used. When the convolved data are measurements, they are associated with uncertainties. This research notice derives how uncertainties propagate through the convolution. While the math is straightforward algebra, the results are not readily available. Here, the uncertainty propagation applied to regularly gridded data is provided. The calculation is done for uncorrelated data and correlated data.

Keywords: astronomy data reduction
Merging Black Holes in the Low-mass and High-mass Gaps from 2 + 2 Quadruple Systems

The origin of the black hole (BH) binary mergers observed by LIGO-Virgo is still uncertain, as are the boundaries of the stellar BH mass function. Stellar evolution models predict a dearth of BHs both at masses ≳50 ${M}_{\odot }$ and ≲5 ${M}_{\odot }$ , thus leaving low- and high-mass gaps in the BH mass function. A natural way to form BHs of these masses is through mergers of neutron stars (NSs; for the low-mass gap) or lower-mass BHs (for the high-mass gap); the low- or high-mass-gap BH produced as a merger product can then be detected by LIGO-Virgo if it merges again with a new companion. We show that the evolution of a 2 + 2 quadruple system can naturally lead to BH mergers with component masses in the low- or high-mass gaps. In our scenario, the BH in the mass gap originates from the merger of two NSs, or two BHs, in one of the two binaries and the merger product is imparted a recoil kick (from anisotropic gravitational wave emission), which triggers its interaction with the other binary component of the quadruple system. The outcome of this three-body interaction is usually a new eccentric compact binary containing the BH in the mass gap, which can then merge again. The merger rate is ∼10-7-10-2 Gpc-3 yr-1 and ∼10-3-10-2 Gpc-3 yr-1 for BHs in the low-mass and high-mass gap, respectively. As the sensitivity of gravitational wave detectors improves, tighter constraints will soon be placed on the stellar BH mass function.

Keywords: stellar kinematics; galaxy kinematics; astrophysical black holes; stellar mass black holes; neutron stars; gravitational waves; gravitational wave sources; gravitational wave astronomy; gravitational wave detectors
The X-Ray Fundamental Plane of the Platinum Sample, the Kilonovae, and the SNe Ib/c Associated with GRBs

A large fraction of gamma-ray burst (GRB) lightcurves (LCs) show X-ray plateaus. We analyze all GRBs with known redshifts presenting plateaus observed by The Neil Gehrels Swift Observatory from its launch until 2019 August. The fundamental plane relation between the rest-frame time and X-ray luminosity at the end of the plateau emission and the peak prompt luminosity holds for all the GRB classes when selection biases and cosmological evolutions are applied. We have discovered two important findings: (1) a new class of long GRBs with good data coverage: the platinum sample; and (2) the platinum, the SNe-LGRB, and the KN-SGRB samples, yield the smallest intrinsic scatter with σplatinum,GRB-SNe = 0.22 ± 0.10 and σKN-SGRB = 0.24 ± 0.12. The SNe-LGRBs are composed of GRBs associated spectroscopically with the SNe Ib,c, the KN-SGRBs are composed by eight GRBs associated with kilonovae or where there could have been such an association. The highest correlation coefficients are yielded for the SN-LGRB-ABC sample, which includes GRBs spectroscopically associated with SNe Ib/c or with a clear optical bump in the LC resembling the SNe Ib/c, ( ${R}_{\mathrm{SN} \mbox{-} \mathrm{LGRB} \mbox{-} \mathrm{ABC}}^{2}=0.95$ ), the SN-LGRBs ( ${R}_{\mathrm{SN} \mbox{-} \mathrm{LGRB}}^{2}=0.91$ ), and the KN-SGRBs ( ${R}_{\mathrm{KN} \mbox{-} \mathrm{SGRB}}^{2}=0.90$ ) when the redshift evolution is considered. These category planes are reliable candidates to use as cosmological tools. Furthermore, the distance from the gold fundamental plane is a crucial discriminant among classes. In fact, we find that the distributions of the distances of the SNe-LGRB, SNe-LGRB-ABC, KN-SGRB, and SGRB samples from the gold fundamental plane are statistically different from the distribution of the gold GRBs' distances from the gold fundamental plane with and without considering evolution cases.

Keywords: gamma-ray bursts
Wakefield Acceleration in a Jet from a Neutrino-driven Accretion Flow around a Black Hole

We have investigated electromagnetic (EM) wave pulses in a jet from a neutrino-driven accretion flow (NDAF) around a black hole (BH). NDAFs are massive accretion disks whose accretion rates are $\dot{M}\,\approx $ 0.01-10 M ⊙ s-1 for stellar-mass BHs. Such an extreme accretion may produce a collimated relativistic outflow like a magnetically driven jet in active galactic nuclei and microquasars. When we consider strong toroidal magnetic field stranded in the inner region of an NDAF disk and magnetic impulses on the jet, we find that they lead to the emanation of high-energy emissions for gamma-ray bursts, as well as high-energy cosmic rays. When Alfvénic wave pulses are generated by episodic immense accretions, they propagate along the large-scale structured magnetic field in the jet. Once the Alfvénic wave pulses reach nearly the speed of light in the underdense condition, they turn into EM wave pulses, which produce plasma wakes behind them. These wakefields exert a collective accelerating force synchronous to the motion of particles. As a result, the wakefield acceleration premises various observational signatures, such as pulsating bursts of high-energy gamma rays from accelerated electrons, pulses of neutrinos from accelerated protons, and protons with maximum energies beyond 1020 eV.

Keywords: high energy astrophysics; accretion; magnetic fields; relativistic jets; gamma-rays; cosmic rays; ultra-high-energy cosmic radiation; neutrino astronomy; theoretical models
A 4 kpc Molecular Gas Lane in Cygnus A

We present the discovery of a 4 kpc molecular gas lane in the Cygnus A host galaxy, using Atacama Large Millimeter/submillimeter Array CO 2-1 observations. The gas lane is oriented roughly perpendicular to the projected radio jet axis. The CO emission generally follows the clumpy dust lanes seen in Hubble Space Telescope I-band images. The total molecular gas mass is 30 × 108 M ⊙ for Milky Way-type clouds, and 3.6 × 108 M ⊙ for starburst conditions. There is a velocity change from the northern to southern CO peaks of about ±175 km s-1, and an apparently smooth velocity gradient between the peaks, although the emission in the central region is weak. In the inner ~0.″5 projected distance from the radio core, comparison of the CO velocities to those observed for H2 2.1218 μm emission shows higher velocities for the vibrationally excited warm molecular gas than the cooler CO 2-1 line emitting gas at similar projected radii. A possible explanation for these different projected velocities at a given radius is that the cooler CO gas is distributed in a clumpy ring at radius ~1.″5-2″, while the warm H2 2.12 μm emitting gas is interior to this ring. Of course, the current data cannot rule out a clumpy, amorphous molecular gas distribution linearly distributed perpendicular to the radio jet axis. We consider surface brightness properties on scales down to ~265 pc, and discuss the Cygnus A results in the context of other radio galaxies with CO emission.

Keywords: radio galaxies; molecular gas; interstellar medium; agn host galaxies
An Injection System for the CHIME/FRB Experiment

Dedicated surveys searching for fast radio bursts (FRBs) are subject to selection effects that bias the observed population of events. Software injection systems are one method of correcting for these biases by injecting a mock population of synthetic FRBs directly into the real-time search pipeline. The injected population may then be used to map intrinsic burst properties onto an expected signal-to-noise ratio (S/N), so long as telescope characteristics such as the beam model and calibration factors are properly accounted for. This paper presents an injection system developed for the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst Project (CHIME/FRB). The system was tested to ensure high detection efficiency, and the pulse calibration method was verified. Using an injection population of ~85,000 synthetic FRBs, we found that the correlation between fluence and S/N for injected FRBs was consistent with that of CHIME/FRB detections in the first CHIME/FRB catalog. We noted that the sensitivity of the telescope varied strongly as a function of the broadened burst width, but not as a function of the dispersion measure. We conclude that some of the machine-learning based Radio Frequency Interference mitigation methods used by CHIME/FRB can be retrained using injection data to increase sensitivity to wide events, and that planned upgrades to the presented injection system will allow for determining a more accurate CHIME/FRB selection function in the near future. We also provide the full injection data sets along with usage tutorials.

Keywords: radio transient sources; radio interferometers
A Unified Treatment of Kepler Occurrence to Trace Planet Evolution. II. The Radius Cliff Formed by Atmospheric Escape

The Kepler mission enabled us to look at the intrinsic population of exoplanets within our galaxy. In period-radius space, the distribution of the intrinsic population of planets contains structure that can trace planet formation and evolution history. The most distinctive feature in period-radius space is the radius cliff, a steep drop-off in occurrence between 2.5 and 4R ⊕ across all period ranges, separating the sub-Neptune population from the rarer Neptunes orbiting within 1 au. Following our earlier work to measure the occurrence rate of the Kepler population, we characterize the shape of the radius cliff as a function of orbital period (10–300 days) as well as insolation flux (9500S ⊕–10S ⊕). The shape of the cliff flattens at longer orbital periods, tracking the rising population of Neptune-sized planets. In insolation, however, the radius cliff is both less dramatic and the slope is more uniform. The difference in this feature between period space and insolation space can be linked to the effect of EUV/X-ray versus bolometric flux in the planet's evolution. Models of atmospheric mass loss processes that predict the location and shape of the radius valley also predict the radius cliff. We compare our measured occurrence rate distribution to population synthesis models of photoevaporation and core-powered mass loss in order to constrain formation and evolution pathways. We find that the models do not statistically agree with our occurrence distributions of the radius cliff in period space or insolation space. Atmospheric mass loss that shapes the radius valley cannot fully explain the shape of the radius cliff.

Keywords: exoplanets; exoplanet evolution; exoplanet atmospheric evolution
A Systematic Search for Outbursting AM CVn Systems with the Zwicky Transient Facility

AM CVn systems are a rare type of accreting binary that consists of a white dwarf and a helium-rich, degenerate donor star. Using the Zwicky Transient Facility (ZTF), we searched for new AM CVn systems by focusing on blue, outbursting stars. We first selected outbursting stars using the ZTF alerts. We cross matched the candidates with Gaia and Pan-STARRS catalogs. The initial selection of candidates based on the Gaia BP-RP contains 1751 unknown objects. We used the Pan-STARRS g-r and r-i color in combination with the Gaia color to identify 59 strong AM CVn candidates. We obtained identification spectra of 35 sources, of which 18 are high-priority candidates, and discovered nine new AM CVn systems and one magnetic CV that shows only He-II lines. Using the outburst recurrence time, we estimate the orbital periods of the nine new AM CVn systems that are in the range of 29-50 minutes. We conclude that targeted follow up of blue, outbursting sources is an efficient method to find new AM CVn systems and we plan to follow up all candidates we identified to systematically study the population of outbursting AM CVn systems.

Keywords: am canum venaticorum stars; cataclysmic variable stars; sky surveys
The SPTpol Extended Cluster Survey

We describe the observations and resultant galaxy cluster catalog from the 2770 deg2 SPTpol Extended Cluster Survey (SPT-ECS). Clusters are identified via the Sunyaev-Zel'dovich (SZ) effect and confirmed with a combination of archival and targeted follow-up data, making particular use of data from the Dark Energy Survey (DES). With incomplete follow-up we have confirmed as clusters 244 of 266 candidates at a detection significance ξ ≥ 5 and an additional 204 systems at 4 < ξ < 5. The confirmed sample has a median mass of M_500c∼ 4.4×1014 M_{⊙} h70-1 and a median redshift of z = 0.49, and we have identified 44 strong gravitational lenses in the sample thus far. Radio data are used to characterize contamination to the SZ signal; the median contamination for confirmed clusters is predicted to be ∼1% of the SZ signal at the ξ > 4 threshold, and <4% of clusters have a predicted contamination >10% of their measured SZ flux. We associate SZ-selected clusters, from both SPT-ECS and the SPT-SZ survey, with clusters from the DES redMaPPer sample, and we find an offset distribution between the SZ center and central galaxy in general agreement with previous work, though with a larger fraction of clusters with significant offsets. Adopting a fixed Planck-like cosmology, we measure the optical richness-SZ mass (λ-M) relation and find it to be 28% shallower than that from a weak-lensing analysis of the DES data - a difference significant at the 4σ level - with the relations intersecting at λ = 60. The SPT-ECS cluster sample will be particularly useful for studying the evolution of massive clusters and, in combination with DES lensing observations and the SPT-SZ cluster sample, will be an important component of future cosmological analyses.

Keywords: galaxy clusters; strong gravitational lensing; large-scale structure of the universe
Estimating the X-Ray Irradiance of the 2003 October 28 Solar Flare

The 2003 October 28 X24 solar flare was saturated in GOES XRS/A for about 10 minutes, near the peak of the event. By using RHESSI X-ray spectral fits during that same time period, the XRS/A time series of the flare and derived quantities like temperature and emission measure can be estimated.

Keywords: solar flares; solar x-ray flares