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Type Iax supernovae (SNe Iax) are proposed to arise from deflagrations of Chandrasekhar mass white dwarfs (WDs). Previous deflagration simulations have achieved good agreement with the light curves and spectra of intermediate-luminosity and bright SNe Iax. However, the model light curves decline too quickly after peak, particularly in red optical and near-infrared (NIR) bands. Deflagration models with a variety of ignition configurations do not fully unbind the WD, leaving a remnant polluted with 56Ni. Emission from such a remnant may contribute to the luminosity of SNe Iax. Here we investigate the impact of adding a central energy source, assuming instantaneous powering by 56Ni decay in the remnant, in radiative transfer calculations of deflagration models. Including the remnant contribution improves agreement with the light curves of SNe Iax, particularly due to the slower post-maximum decline of the models. Spectroscopic agreement is also improved, with intermediate-luminosity and faint models showing greatest improvement. We adopt the full remnant 56Ni mass predicted for bright models, but good agreement with intermediate-luminosity and faint SNe Iax is only possible for remnant 56Ni masses significantly lower than those predicted. This may indicate that some of the 56Ni decay energy in the remnant does not contribute to the radiative luminosity but instead drives mass ejection, or that escape of energy from the remnant is significantly delayed. Future work should investigate the structure of remnants predicted by deflagration models and the potential roles of winds and delayed energy escape, as well as extend radiative transfer simulations to late times.

Context.Time-delay cosmography uses strong gravitational lensing of a time-variable source to infer the Hubble constant. The measurement is independent from both traditional distance ladder and CMB measurements. An accurate measurement with this technique requires considering the effects of objects along the line of sight outside the primary lens, which is quantified by the external convergence (κ_ext). In absence of such corrections,H₀will be biased towards higher values in overdense fields and lower values in underdense fields.

Aims.We discuss the current state of the methods used to account for environment effects. We present a new software package built for this kind of analysis and others that can leverage large astronomical survey datasets. We apply these techniques to the SDSS J0924+0219 strong lens field.

Methods.We infer the relative density of the SDSS J0924+0219 field by computing weighted number counts for all galaxies in the field, and comparing to weighted number counts computed for a large number of fields in a reference survey. We then compute weighted number counts in the Millennium Simulation and compare these results to infer the external convergence of the lens field.

Results.Our results show the SDSS J0924+0219 field is a fairly typical line of sight, with medianκ_ext = −0.012 and standard deviationσ_κ = 0.028.

Near-ideal behavior in Schottky contacts to Si-doped AlN was observed as evidenced by a low ideality factor of 1.5 at room temperature. A temperature-independent Schottky barrier height of 1.9 eV was extracted from temperature-dependent I–V measurements. An activation energy of ∼300 meV was observed in the series resistance, which corresponded to the ionization energy of the deep Si donor state. Both Ohmic and Schottky contacts were stable up to 650 °C, with around four orders of magnitude rectification at this elevated temperature. These results demonstrate the potential of AlN as a platform for power devices capable of operating in extreme environments.

In the first of a planned sequence of articles, we present a simple method for reconstructing radial density structures of the solar corona in the vicinity of the Parker Solar Probe (PSP) near and during perihelion passes. We describe how we model the apparent kinematics of stationary K-corona striae from the PSP Wide-field Imager for Parker Solar Probe (WISPR) viewpoint using a simple two-parameter model, form a partial basis of the data space that is a WISPR image sequence, and change the basis from image coordinates to “tomographic coordinates” in order to determine the parameters of such features. We apply the method to a simple three-dimensional model of a WISPR coronal flythrough, demonstrate the ways that it succeeds and fails, and discuss possible improvements to the sensitivity and applicability of the method for real WISPR data.

The Communications/Navigation Outages Forecast System satellite mission was designed to investigate the ionospheric conditions that lead to the formation of irregularities. Here, we have studied the effect of magnetic storms on the formation and evolution of plasma bubbles during the satellite's lifetime (2008–2015). During this period encompassing solar minimum and maximum conditions, many magnetic storms of varying intensity developed, producing a unique and rich data set of 248 storms (14 intense, 69 moderate, and 165 weak) that occurred during the same timeframe to examine the role of external magnetospheric drivers in the production and dynamics of equatorial plasma bubbles. We have used the Planar Langmuir Probe and Ion Velocity Meter instruments to elucidate the role of magnetic storm intensity on the bubble's depth, internal speed, width, occurrence, and lifetime. The pre‐reversal enhancement (PRE) tends to increase during the main phase and when B_Zis southward. New bubbles occur during large excursions of the PRE value. The bubble lifetime extends and remains active during the main and part of the recovery phase. The plasma velocity within the bubbles increases and typically becomes over 100 m/s during significant PRE and B_Znegative times. The depth of bubbles reaches values close to 100% during intense storms. In general, the intensity of the storms seems to control and augment the plasma bubbles' depth, width, and internal velocity.

The current and next observation seasons will detect hundreds of gravitational waves (GWs) from compact binary systems coalescence at cosmological distances. When combined with independent electromagnetic measurements, the source redshift will be known, and we will be able to obtain precise measurements of the Hubble constant H0 via the distance–redshift relation. However, most observed mergers are not expected to have electromagnetic counterparts, which prevents a direct redshift measurement. In this scenario, one possibility is to use the dark sirens method that statistically marginalizes over all the potential host galaxies within the GW location volume to provide a probabilistic source redshift. Here we presented H0 measurements using two new dark sirens compared to previous analyses using DECam data: GW190924$\_$021846 and GW200202$\_$154313. The photometric redshifts of the possible host galaxies of these two events are acquired from the DECam Local Volume Exploration Survey (DELVE) carried out on the Blanco telescope at Cerro Tololo. The combination of the H0 posterior from GW190924$\_$021846 and GW200202$\_$154313 together with the bright siren GW170817 leads to $H_{0} = 68.84^{+15.51}_{-7.74}\, \rm {km\, s^{-1}\, Mpc^{-1}}$. Including these two dark sirens improves the 68  per cent confidence interval (CI) by 7  per cent over GW170817 alone. This demonstrates that the addition of well-localized dark sirens in such analysis improves the precision of cosmological measurements. Using a sample containing 10 well-localized dark sirens observed during the third LIGO/Virgo observation run, without the inclusion of GW170817, we determine a measurement of $H_{0} = 76.00^{+17.64}_{-13.45}\, \rm {km\, s^{-1}\, Mpc^{-1}}$.

Type Ia supernovae (SNe Ia) are important cosmological tools, probes of binary star evolution, and contributors to cosmic metal enrichment; yet, a definitive understanding of the binary star systems that produce them remains elusive. Of particular interest is the identity of the mass-donor companion to the exploding carbon–oxygen white dwarf (CO WD). In this work, we present early-time (first observation within 10 days post-explosion) radio observations of six nearby (within 40 Mpc) SNe Ia taken by the Jansky Very Large Array, which are used to constrain the presence of synchrotron emission from the interaction between ejecta and circumstellar material (CSM). The two motivations for these early-time observations are: (1) to constrain the presence of low-density winds and (2) to provide an additional avenue of investigation for those SNe Ia observed to have early-time optical/UV excesses that may be due to CSM interaction. We detect no radio emission from any of our targets. Toward our first aim, these non-detections further increase the sample of SNe Ia that rule out winds from symbiotic binaries and strongly accreting white dwarfs. and discuss the dependence on underlying model assumptions and how our observations represent a large increase in the sample of SNe Ia with low-density wind constraints. For the second aim, we present a radiation hydrodynamics simulation to explore radio emission from an SN Ia interacting with a compact shell of CSM, and find that relativistic electrons cannot survive to produce radio emission despite the rapid expansion of the shocked shell after shock breakout. The effects of model assumptions are discussed for both the wind and compact shell conclusions.