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The upcoming Rubin Observatory and subsequent follow-up observations should improve the determination of the Hubble constant ($H_0$) via time-delay cosmography of strongly lensed type II supernovae (LSNe II), by enabling the detection of many more such events. In our previous work, we developed a method for determining the supernova (SN) phase from spectral absorption features. Because obtaining spectra of faint targets such as distant SN II is expensive, we examined how low-resolution spectra influence the precision of time-delay retrieval, and consequently the precision on $H_0$. We considered spectral resolutions $R = \fracλ{Δλ}$ between 100 and 250, and we investigated three signal-to-noise ratio ($S/N$) values of 10, 15, and 20, for each resolution. Furthermore, we forecast the precision on $H_{0}$ achievable with $S/N=10$ and compared the observing time required to reach it with ground-based and space-based facilities. We find that the time delay can be determined without bias and with uncertainties as low as 1.3 days for the investigated resolutions and $S/N$ values when we combine time-delay measurements of multiple absorption lines. For a typical LSN II system (absolute magnitude $\sim-$17 mag in the rest-frame V band, source redshift of \zs = 0.8), the required exposure times range from multiple hours for ground-based observations to a few minutes for space-based observations with the JWST. Our predictions on the precision of $H_0$ for a single lensed SN range from 14.2\% for $R = 100$ and $S/N$ = 10 to 7.5\% for $R = 250$ and $S/N$ = 20, enabling a 1\% determination of $H_0$ from $\sim$20 lensed SNe in the coming years.

Current Mars thermospheric temperatures databases have course temporal resolution due to either a lack of data or a need to average over several orbits of data, preventing the study of short-term, rapid changes to the Mars thermosphere. In this study, we present a new Mars thermosphere temperature database derived from individual orbits of Argon density data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) Neutral Gas and Ion Mass Spectrometer instrument from 01/01/2016 to 12/31/2020 using a Newton gradient descent inverse method. This was enabled by the creation of secondary products like gravity wave potential energy, ${E}_{p}$, the Knudsen number, ${K}_{n}$, and pressure, designed to indicate when the variability in the data is beyond the assumptions of the temperature derivation and provide a better vertical axis to observe changes in the temperature. Here we present validations of the data set against previous models and data alongside some simple analysis of the temperatures in order to demonstrate the sensitivity of the data set to the nuances of the Martian thermosphere. This data set can better enable the study of thermosphere response to solar activity, dust events, and gravity waves.

We present a cosmological reassessment of light sterile-neutrino scenarios, examining whether current observations exclude sterile neutrinos as a class or primarily constrain the fully thermalized case. We consider three distinct realizations; (i) a fully thermalized sterile (FTS) species, (ii) a different-temperature sterile-neutrino thermal relic (DTS) relative to the active neutrino background and (iii) a Dodelson-Widrow-like (DW) sterile neutrino with reduced phase-space normalization. Constraints are derived within both <inline-formula><mml:math><mml:mrow><mml:mi>Λ</mml:mi><mml:mi>CDM</mml:mi></mml:mrow></mml:math></inline-formula> and the CPL dynamical dark-energy framework using combinations of Planck-Cosmic Microwave Background data, DESI DR2 BAO measurements, and the PantheonPlus and Union3 Type Ia supernova samples. For baseline data combinations without a local <inline-formula><mml:math><mml:msub><mml:mi>H</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math></inline-formula> prior, the FTS scenario is strongly disfavored in both cosmological models. Adding the local <inline-formula><mml:math><mml:msubsup><mml:mi>H</mml:mi><mml:mn>0</mml:mn><mml:mrow><mml:mi>DN</mml:mi></mml:mrow></mml:msubsup></mml:math></inline-formula> prior allows <inline-formula><mml:math><mml:mi>Λ</mml:mi><mml:mi>CDM</mml:mi><mml:mo>+</mml:mo><mml:mi>FTS</mml:mi></mml:math></inline-formula> to accommodate the high local <inline-formula><mml:math><mml:msub><mml:mi>H</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math></inline-formula> value and become statistically competitive with standard <inline-formula><mml:math><mml:mi>Λ</mml:mi><mml:mi>CDM</mml:mi></mml:math></inline-formula> once SNIa data are included, although the sterile-neutrino mass remains consistent with zero. By contrast, partially populated sterile-neutrino scenarios remain viable: the DW realization is broadly compatible with current observations, while the DTS scenario yields the least cosmological pressure among the cases considered. Overall, cosmological data mainly require a strongly suppressed effective sterile abundance, leading to tight constraints on <inline-formula><mml:math><mml:mrow><mml:msubsup><mml:mrow><mml:mi>m</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mi>eff</mml:mi></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula> while allowing substantially weaker bounds on the physical sterile mass. We conclude that current observations do not generically exclude sterile neutrinos, but rather place strong pressure on fully thermalized or highly populated scenarios, highlighting the importance of production history and phase-space distribution when interpreting cosmological constraints.

Pulsar timing arrays' hint for a stochastic gravitational-wave background (SGWB) leverages the expectations of a future detection in the millihertz band, particularly with the LISA space mission. However, finding a SGWB with a single orbiting detector is challenging: It calls for cautious modelling of instrumental noise, which is also mainly stochastic. It was shown that agnostic noise reconstruction methods provide robustness in the detection process. We build on previous work to include more realistic instrumental simulations and additional degrees of freedom in the noise inference model and analyze the impact of LISA's sensitivity to SGWBs. Particularly, we model the two main types of noise sources with separate transfer functions and power spectral density spline fitting. We assess the detectability bounds and their dependence on the flexibility of the noise model and on the prior probability, allowing us to refine previously reported results.

X-ray absorption variability in active galactic nuclei (AGN) provides key constraints on the structure and dynamics of the circumnuclear obscuring medium, the so-called torus. A fraction of nearby AGN, however, have been classified as nonvariable in line-of-sight (LoS) column density based on limited temporal coverage. We present the first systematic study of a sample of 11 local (z &lt;= 0.1) obscured (N<SUB>H</SUB> &gt;= 10<SUP>22</SUP> cm<SUP>-2</SUP>) AGN, initially classified as nonvariable. The sample is selected from the Swift Burst Alert Telescope (Swift-BAT) 100-month catalog and comprises 60 observations from Chandra, XMM-Newton, and NuSTAR, spanning timescales from days to nearly two decades. We simultaneously model all available spectra for each source adopting physically motivated torus models: X-skirtor, RXTorusD, and UXCLUMPY. This approach allows us to derive the global properties of the obscurer while tracking possible epoch-to-epoch variations in the LoS column density and intrinsic X-ray emission. We find that the original nonvariable classification (based on only two X-ray observations) is frequently not robust: Clear N<SUB>H,LoS</SUB> variability is detected in half of the sample, whereas 7 out of 10 AGN require intrinsic flux variability, with the rest showing flux--N<SUB>H,LoS</SUB> degeneracies. We also find that the probability of identifying absorption variability increases with the number of observations, and the largest column density changes preferentially occur on long timescales, consistent with absorption by extended, structured clouds on torus scales. These findings support a clumpy and dynamic obscuring medium as a common feature of nearby AGN and highlight the importance of long-term X-ray monitoring for accurately characterizing AGN obscuration.