Papers for Monday, Sep 09 2024

Integrated optics are used to achieve astronomical interferometry inside robust and compact materials, improving the instruments stability and sensitivity. In order to perform differential phase measurements at the H$\alpha$ line (656.3 nm) with the 600-800 nm spectro-interferometer FIRST, a photonic integrated circuit (PIC) is being developed. This PIC performs the visible combination of the beams coming from the telescope pupil sub-apertures. In this work, TEEM Photonics waveguides fabricated by $K_+:Na_+$ ion exchange in glass are characterized in terms of single-mode range and mode field diameter. The waveguide diffused index profile is modeled on Beamprop software. FIRST beam combiner building blocks are simulated, especially achromatic directional couplers and passive $\pi/2$ phase shifters for a potential ABCD interferometric combination.

One of the main endeavors of the field of exoplanetary sciences is the characterization of exoplanet atmospheres on a population level. The current method of choice to accomplish this task is transmission spectroscopy, where the apparent radius of a transiting exoplanet is measured at multiple wavelengths in search of atomic and molecular absorption features produced by the upper atmosphere constituents. To extract the planetary radius from a transit light curve, it is necessary to account for the decrease in luminosity away from the center of the projected stellar disk, known as the limb darkening. Physically-motivated parametrizations of the limb darkening, in particular of the quadratic form, are commonly used in exoplanet transit light-curve fitting. Here, we show that such parametrizations can introduce significant wavelength-dependent biases in the transmission spectra currently obtained with all instrument modes of the JWST, and thus have the potential to affect atmospheric inferences. To avoid such biases, we recommend the use of standard limb-darkening parametrizations with wide uninformative priors that allow for non-physical stellar intensity profiles in the transit fits, and thus for a complete and symmetrical exploration of the parameter space. We further find that fitting the light curves at the native resolution results in errors on the measured transit depths that are significantly smaller compared to light curves that are binned in wavelength before fitting, thus potentially maximizing the amount of information that can be extracted from the data.

The Transiting Exoplanet Survey Satellite (TESS) has enabled the discovery of numerous tidally tilted pulsators (TTPs), which are pulsating stars in close binaries where the presence of a tidal bulge has the effect of tilting the primary star's pulsation axes into the orbital plane. Recently, the modeling framework developed to analyze TTPs has been applied to the emerging class of tri-axial pulsators, which exhibit nonradial pulsations about three perpendicular axes. In this work, we report on the identification of the second-ever discovered tri-axial pulsator, with sixteen robustly-detected pulsation multiplets, of which fourteen are dipole doublets separated by 2$\nu_{\rm orb}$. We jointly fit the spectral energy distribution (SED) and TESS light curve of the star, and find that the primary is slightly evolved off the zero-age main sequence, while the less massive secondary still lies on the zero-age main sequence. Of the fourteen doublets, we associate eight with $Y_{10x}$ modes and six with novel $Y_{10y}$ modes. We exclude the existence of $Y_{11x}$ modes in this star and show that the observed pulsation modes must be $Y_{10y}$. We also present a toy model for the tri-axial pulsation framework in the context of this star. The techniques presented here can be utilized to rapidly analyze and confirm future tri-axial pulsator candidates.

Context. Dust coagulation and fragmentation impact the structure and evolution of protoplanetary disks and set the initial conditions for planet formation. Dust grains dominate the opacities, they determine the cooling times of the gas, they influence the ionization state of the gas, and the grain surface area is an important parameter for the chemistry in protoplanetary disks. Therefore, dust evolution should not be ignored in numerical studies of protoplanetary disks. Available dust coagulation models are, however, too computationally expensive to be implemented in large-scale hydrodynamic simulations. This limits detailed numerical studies of protoplanetary disks, including these effects, mostly to one-dimensional models. Aims. We aim to develop a simple - yet accurate - dust coagulation model that can be implemented in hydrodynamic simulations of protoplanetary disks. Our model shall not significantly increase the computational cost of simulations and provide information about the local grain size distribution. Methods. The local dust size distributions are assumed to be truncated power laws. Such distributions can be characterized by two dust fluids (large and small grains) and a maximum particle size, truncating the power law. We compare our model to state-of-the-art dust coagulation simulations and calibrate it to achieve a good fit with these sophisticated numerical methods. Results. Running various parameter studies, we achieved a good fit between our simplified three-parameter model and DustPy, a state-of-the-art dust coagulation software. Conclusions. We present TriPoD, a sub-grid dust coagulation model for the PLUTO code. With TriPoD, we can perform two-dimensional, vertically integrated dust coagulation simulations on top of a hydrodynamic simulation. Studying the dust distributions in two-dimensional vortices and planet-disk systems is thus made possible.

Semi-analytic methods can generate baryon-corrected fields from N-body simulations (``baryonification'') and are rapidly becoming a ubiquitous tool in modeling structure formation on non-linear scales. We extend this formalism to consistently model the weak lensing and thermal Sunyaev-Zeldovich (tSZ) fields directly on the full-sky, with an emphasis on higher-order correlations. We use the auto- and cross- $N$th-order moments, with $N \in \{2, 3, 4\}$, as a summary statistic of the lensing and tSZ fields, and show that our model can jointly fit these statistics measured in IllustrisTNG to within measurement uncertainties, for scales above $\gtrsim 1 {\rm Mpc}$ and across multiple redshifts. The model predictions change only minimally when including additional information from secondary halo properties, such as halo concentration and ellipticity. Each individual moment is dependent on halos of different mass ranges and has different sensitivities to the model parameters. A simulation-based forecast on the ULAGAM simulation suite shows that the combination of all moments, measured from current and upcoming lensing and tSZ surveys, can jointly constrain cosmology and baryons to high precision. The lensing and tSZ field are sensitive to different combinations of the baryonification parameters, with degeneracy directions that are often orthogonal, and the combination of the two fields leads to significantly better constraints on both cosmology and astrophysics. Our pipeline for map-level baryonification is publicly available at this https URL.

Stellar evolution theory predicts that the Sun was fainter in the past, which can pose difficulties for understanding Earth's climate history. One proposed solution to this Faint Young Sun problem is a more luminous Sun in the past. In this paper, we address the robustness of the solar luminosity history using the YREC code to compute solar models including rotation, magnetized winds, and the associated mass loss. We present detailed solar models, including their evolutionary history, which are in excellent agreement with solar observables. Consistent with prior standard models, we infer a high solar metal content. We provide predicted X-ray luminosities and rotation histories for usage in climate reconstructions and activity studies. We find that the Sun's luminosity deviates from the standard solar model trajectory by at most 0.5% during the Archean (corresponding to a radiative forcing of 0.849 W m$^{-2}$). The total mass loss experienced by solar models is modest because of strong feedback between mass and angular momentum loss. We find a maximum mass loss of $1.35 \times 10^{-3} M_\odot$ since birth, at or below the level predicted by empirical estimates. The associated maximum luminosity increase falls well short of the level necessary to solve the FYS problem. We present compilations of paleotemperature and CO$_2$ reconstructions. 1-D "inverse" climate models demonstrate a mismatch between the solar constant needed to reach high temperatures (e.g. 60-80 $^{\circ}$C) and the narrow range of plausible solar luminosities determined in this study. Maintaining a temperate Earth, however, is plausible given these conditions.

Triple stars are prevalent within the population of observed stars. Their evolution, compared to binaries, is notably more complex, influenced by unique dynamical, tidal, and mass transfer processes. Understanding these phenomena is essential for a comprehensive insight into multistar evolution and the formation of energetic transients, including gravitational-wave mergers. Our study probes the evolution of triple star systems when the tertiary fills its Roche lobe and transfers mass to the inner binary, potentially forming GW sources with distinct properties. We develop an analytical model for hierarchical triples undergoing stable mass transfer from the tertiary. Using population synthesis simulations, we investigate triples with a Roche-lobe filling tertiary and an inner binary black hole. These systems originate from inner binaries undergoing chemically homogeneous evolution. Our analysis includes populations with metallicities of Z=0.005 and Z=0.0005, focusing on primary components with initial masses of 20 to 100 M_sun, and inner and outer orbital separations up to 40 R_sun and 10^5 R_sun, respectively. Our results show that mass transfer predominantly leads to orbital shrinkage of the inner binary, non-zero eccentricities, and expansion of the outer orbit. Among systems with CHE inner binaries, 9.5% result in mass transfer from the tertiary onto an inner BBH. We predict high formation efficiency of GW mergers, ranging from 85.1% to 100% at Z=0.005 and 100% at Z=0.0005, with short delay times. Local merger rates are projected to be between 0.69 to 1.74 Gpc^-3 yr^-1. A fraction of these BBH mergers, entering the LISA and aLIGO frequency bands, may still be accreting gas, potentially producing a strong electromagnetic counterpart. EM signals vary significantly based on model assumptions, ranging from less than 0.03% to 46.8% of all mergers if circumbinary disk formation is allowed.

We present the first 3D kinematic analysis of multiple stellar populations (MPs) in a representative sample of 16 Galactic globular clusters (GCs). For each GC in the sample we studied the MP line-of-sight, plane-of-the-sky and 3D rotation as well as the velocity distribution anisotropy. The differences between first- (FP) and second-population (SP) kinematic patterns were constrained by means of parameters specifically defined to provide a global measure of the relevant physical quantities and to enable a meaningful comparison among different clusters. Our analysis provides the first observational description of the MP kinematic properties and of the path they follow during the long-term dynamical evolution. In particular, we find evidence of differences between the rotation of MPs along all velocity components with the SP preferentially rotating faster than the FP. The difference between the rotation strength of MPs is anti-correlated with the cluster dynamical age. We observe also that FPs are characterized by isotropic velocity distributions at any dynamical age probed by our sample. On the contrary, the velocity distribution of SP stars is found to be radially anisotropic in dynamically young clusters and isotropic at later evolutionary stages. The comparison with a set of numerical simulations shows that these observational results are consistent with the long-term evolution of clusters forming with an initially more centrally concentrated and more rapidly rotating SP subsystem. We discuss the possible implications these findings have on our understanding of MP formation and early evolution.

The mid-infrared water vapor emission spectrum provides a novel way to characterize the delivery of icy pebbles towards the innermost ($<5$ au) regions of planet-forming disks. Recently, JWST MIRI-MRS showed that compact disks exhibit an excess of low-energy water vapor emission relative to extended multi-gapped disks, suggesting that icy pebble drift is more efficient in the former. We carry out detailed emission line modeling to retrieve the excitation conditions of rotational water vapor emission in a sample of four compact and three extended disks within the JDISC Survey. We present two-temperature H$_2$O slab model retrievals and, for the first time, constrain the spatial distribution of water vapor by fitting parametric radial temperature and column density profiles. Such models statistically outperform the two-temperature slab fits. We find a correlation between the observable hot water vapor mass and stellar mass accretion rate, as well as an anti-correlation between cold water vapor mass and sub-mm dust disk radius, confirming previously reported water line flux trends. We find that the mid-IR spectrum traces H$_2$O with temperatures down to 180-300 K, but the coldest 150-170 K gas remains undetected. Furthermore the H$_2$O temperature profiles are generally steeper and cooler than the expected `super-heated' dust temperature in passive irradiated disks. The column density profiles are used to estimate icy pebble mass fluxes, which suggest that compact and extended disks may produce markedly distinct inner-disk exoplanet populations if local feeding mechanisms dominate their assembly.

Modelling complex line emission in the interstellar medium (ISM) is a degenerate, high-dimensional problem. Here, we present McFine, a tool for automated multi-component fitting of emission lines with complex hyperfine structure, in a fully automated way. We use Markov chain Monte Carlo (MCMC) to efficiently explore the complex parameter space, allowing for characterising model denegeracies. This tool allows for both local thermodynamic equilibrium (LTE) and radiative-transfer (RT) models. McFine can fit individual spectra and data cubes, and for cubes encourage spatial coherence between neighbouring pixels. It is also built to fit the minimum number of distinct components, to avoid overfitting. We have carried out tests on synthetic spectra, where in around 90~per~cent of cases it fits the correct number of components, otherwise slightly fewer components. Typically, $T_{\rm ex}$ is overestimated and $\tau$ underestimated, but accurate within the estimated uncertainties. The velocity and line widths are recovered with extremely high accuracy, however. We verify McFine by applying to a large Atacama Large Millimeter/submillimeter Array (ALMA) N$_2$H$^+$ mosaic of an high-mass star forming region, G316.75-00.00. We find a similar quality of fit to our synthetic tests, aside from in the active regions forming O-stars, where the assumptions of Gaussian line profiles or LTE may break down. To show the general applicability of this code, we fit CO(J = 2-1) observations of NGC 3627, a nearby star-forming galaxy, again obtaining excellent fit quality. McFine provides a fully automated way to analyse rich datasets from interferometric observations, is open source, and pip-installable.

Accounting for selection effects in supernova type Ia (SN Ia) cosmology is crucial for unbiased cosmological parameter inference -- even more so for the next generation of large, mostly photometric-only surveys. The conventional "bias correction" procedure has a built-in systematic bias towards the fiducial model used to derive it and fails to account for the additional Eddington bias that arises in the presence of significant redshift uncertainty. On the other hand, Bayesian hierarchical models scale poorly with the data set size and require explicit assumptions for the selection function that may be inaccurate or contrived. To address these limitations, we introduce STAR NRE, a simulation-based approach that makes use of a conditioned deep set neural network and combines efficient high-dimensional global inference with subsampling-based truncation in order to scale to very large survey sizes while training on sets with varying cardinality. Applying it to a simplified SN Ia model consisting of standardised brightnesses and redshifts with Gaussian uncertainties and a selection procedure based on the expected LSST sensitivity, we demonstrate precise and unbiased inference of cosmological parameters and the redshift evolution of the volumetric SN Ia rate from ~100 000 mock SNae Ia. Our inference procedure can incorporate arbitrarily complex selection criteria, including transient classification, in the forward simulator and be applied to complex data like light curves. We outline these and other steps aimed at integrating STAR NRE into an end-to-end simulation-based pipeline for the analysis of future photometric-only SN Ia data.

We present a multi-wavelength analysis of MCG+11-11-032, a nearby AGN with the unique classification of both a binary and a dual AGN candidate. With new Chandra observations we aim to resolve any dual AGN system via imaging data, and search for signs of a binary AGN via analysis of the X-ray spectrum. Analyzing the Chandra spectrum, we find no evidence of previously suggested double-peaked Fe K$\alpha$ lines; the spectrum is instead best fit by an absorbed powerlaw with a single Fe K$\alpha$ line, as well as an additional line centered at $\approx$7.5 keV. The Chandra observation reveals faint, soft, and extended X-ray emission, possibly linked to low-level nuclear outflows. Further analysis shows evidence for a compact, hard source -- MCG+11-11-032 X2 -- located 3.27'' from the primary AGN. Modeling MCG+11-11-032 X2 as a compact source, we find that it is relatively luminous ($L_{\text{2$-$10 keV}} = 1.52_{-0.48}^{+0.96}\times 10^{41}$ erg s$^{-1}$), and the location is coincident with an compact and off-nuclear source resolved in Hubble Space Telescope infrared (F105W) and ultraviolet (F621M, F547M) bands. Pairing our X-ray results with a 144 MHz radio detection at the host galaxy location, we observe X-ray and radio properties similar to those of ESO 243-49 HLX-1, suggesting that MCG+11-11-032 X2 may be a hyper-luminous X-ray source. This detection with Chandra highlights the importance of a high-resolution X-ray imager, and how previous binary AGN candidates detected with large-aperture instruments benefit from high-resolution follow-up. Future spatially resolved optical spectra, and deeper X-ray observations, can better constrain the origin of MCG+11-11-032 X2.

Broad absorption line (BAL) outflows are commonly detected in active galactic nuclei (AGN), but their driving mechanism remains poorly constrained. Here we investigate whether radiation pressure on dust can adequately explain the BAL phenomenon observed in quasars. In the framework of our AGN radiative dusty feedback scenario, we show that dust-driven outflows can reach BAL wind-like velocities ($v \sim 10^4$ km/s) on galactic scales ($r \lesssim 1$ kpc). This is consistent with recent observations indicating that BAL acceleration typically occurs on scales of $\sim 10$ pc, and that the majority of BAL outflows are located at galactocentric radii greater than $\sim 100$ pc. We derive the outflow radial velocity profile and compute the associated outflow momentum rate and kinetic power, which are found to be in agreement with the outflow energetics measured in BAL quasars. Therefore radiation pressure on dust may account for the observed BAL outflow dynamics and energetics. Furthermore, we consider BAL clouds/clumps (leading to a clumpy BAL flow characterised by a wide range of outflowing velocities), and we analyse how the resulting covering factors affect the shape of the absorption line profiles. We conclude that dust-driven BAL outflows may provide a significant contribution to AGN feedback on galactic scales.

Multi-planet system architectures are frequently used to constrain possible formation and evolutionary pathways of observed exoplanets. Therefore, understanding the predictive and descriptive power of empirical models of these systems is critical to understanding their formation histories. Additionally, if empirical models can reproduce architectures over a range of scales, transit and radial velocity observations can be more easily and effectively used to inform future microlensing, astrometric, and direct imaging surveys. We analyze 52 TESS multi-planet systems previously studied using Dynamite (Dietrich & Apai 2020), who used TESS data alongside empirical models based on Kepler planets to predict additional planets in each system. We analyze additional TESS data to search for these predicted planets. We thereby evaluate the degree to which these models can be used to predict planets in TESS multi-planet systems. Specifically, we study whether a period ratio method or clustered period model is more predictive. We find that the period ratio model predictions are most consistent with the planets discovered since 2020, accounting for detection sensitivity. However, neither model is highly predictive, highlighting the need for additional data and nuanced models to describe the full population. Improved eccentricity and dynamical stability prescriptions incorporated into Dynamite provide a modest improvement in the prediction accuracy. We also find that the current sample of 183 TESS multi-planet systems are are highly dynamically packed, and appear truncated relative to detection biases. These attributes are consistent with the Kepler sample, and suggest a highly efficient formation process.

The Askaryan Radio Array (ARA) is an in-ice ultrahigh energy (UHE) neutrino experiment at the South Pole. ARA aims to detect the radio emissions from neutrino-induced particle showers using in-ice clusters of antennas buried ${\sim}200$ m deep on a roughly cubical lattice with side length of ${\sim}10$ m. ARA has five such independent stations which have collectively accumulated ${\sim}30$ station-years of livetime through 2023. The fifth station of ARA has an additional sub-detector, known as the phased array, which pioneered an interferometric trigger constructed by beamforming the signals of $7$ tightly packed, vertically-polarized antennas. This scheme has been demonstrated to significantly improve the trigger efficiency for low SNR signals. In this talk, we will present the current state of the first array-wide diffuse neutrino search using $24$ station-years of data (through 2021). We anticipate that this analysis will result in the first UHE neutrino observation or world-leading limits from a radio neutrino detector below $100$ EeV. Additionally, this analysis will demonstrate the feasibility for multi-station in-ice radio arrays to successfully conduct an array-wide neutrino search -- paving the way for future, large detector arrays such as RNO-G and IceCube-Gen2 Radio.

The $\lambda 21$cm H I emission that is used to trace the gas to dust ratio at high Galactic latitudes has contributions from material beyond the Milky Way disk, with uncertain and likely sub-Solar metallicity and dust content. These contributions can be isolated kinematically and their presence is clear for sightlines with small mean reddening $<$E(B-V)$>$ $\la$ 0.03 mag, which have mean ratios $<$N(H I)$>$/$<$E(B-V)$>$ that are 20-50\% above the high latitude Galactic average $<$N(H I)$>/<$E(B-V)$>=8.3\times10^{21}$cm$^{-2}$mag$^{-1}$. By mapping N(H I) and E(B-V) across H I High Velocity Cloud complexes and the Magellanic Clouds we show that the reddening of this kinematically-isolated gas is on average five times smaller per H I than the high latitude average. However, the aggregate contribution of this gas is small and $<$N(H I)$>/<$E(B-V)$>=8.3\times10^{21}$cm$^{-2}$mag$^{-1}$ is the appropriate value for Galactic gas seen at high latitude using the H I and reddening measures employed here and in our previous work.

Stable isotopic ratios constitute powerful tools for unraveling the thermal and irradiation history of volatiles. In particular, we can use our knowledge of the isotopic fractionation processes active during the various stages of star, disk and planet formation to infer the origins of different volatiles with measured isotopic patterns in our own solar system. Observations of planet-forming disks with the Atacama Large Millimeter/submillimeter Array (ALMA) now readily detect the heavier isotopologues of C, O and N, while the isotopologue abundances and isotopic fractionation mechanisms of sulfur species are less well understood. Using ALMA observations of the SO and SO2 isotopologues in the nearby, molecule-rich disk around the young star Oph-IRS 48 we present the first constraints on the combined 32S/34S and 32S/33S isotope ratios in a planet-forming disk. Given that these isotopologues likely originate in relatively warm gas (>50 K), like most other Oph-IRS 48 volatiles, SO is depleted in heavy sulfur while SO2 is enriched compared to solar system values. However, we cannot completely rule out a cooler gas reservoir, which would put the SO sulfur ratios more in line with comets and other solar system bodies. We also constrain the S18O/SO ratio and find the limit to be consistent with solar system values given a temperature of 60 K. Together these observations show that we should not assume solar isotopic values for disk sulfur reservoirs, but additional observations are needed to determine the chemical origin of the abundant SO in this disk, inform on what isotopic fractionation mechanism(s) are at play, and aid in unravelling the history of the sulfur budget during the different stages of planet formation.

In a recent study by Euclid collaboration, the halo mass function (HMF) has been fitted with accuracy better than $1\%$ for the $\Lambda$CDM model. Several parameters were introduced and fitted against N-body simulations, assuming the usual linearly extrapolated matter density contrast at the collapse time, $\delta_c$, as a basic threshold for halo formation. As a result, a new function that multiplies $\delta_c$ was introduced, producing an effective threshold that varies both with redshift and mass scale. We show that the redshift evolution of this effective threshold is similar to the one of the linear extrapolated matter density contrast at the virialization time, $\delta_{\rm v}$. Assuming the Euclid HMF as a fiducial model, we refit the Sheth-Tormen (ST) HMF using $\delta_{\rm v}$ as a threshold. This new fit improves the agreement between ST-HMF and the Euclid one with respect to Despali et al. (2016) fit, specially at high masses. Interestingly, the parameters $a$ and $p$ in this refit have values closer to the Press-Schechter limit of the ST-HMF, showing that the use of $\delta_{\rm v}$ can provide semi-analytical HMF less dependent on extra parameters. Moreover, we analyze the consistency of the ST-HMF fitted with $\delta_{\rm v}$ in smooth dark energy models with time-varying equation of state, finding an overall good agreement with the evolution of halo abundances expected from the linear evolution of perturbations and the Euclid HMF extrapolated to these scenarios. These findings suggest that the use $\delta_{\rm v}$ as a basic function to describe the threshold for halo formation can be a good guide when considering extrapolations for models beyond $\Lambda$CDM, which are typically harder to study in simulations.

A central challenge in the field of stellar astrophysics lies in accurately determining the mass of isolated stars. However, for pulsating white dwarf (WD) stars, the task becomes more tractable due to the availability of multiple approaches such as spectroscopy, asteroseismology, astrometry, and photometry. The objective of this work is to compare the asteroseismological and spectroscopic mass values of WDs in detail and, in turn, to compare them with the masses derived using astrometric parallaxes/distances and photometry. Our analysis encompasses a selection of pulsating WDs with different surface chemical abundances that define the main classes of variable WDs. We calculated their spectroscopic masses, compiled seismological masses, and determined astrometric masses. We also derived photometric masses, when possible. Subsequently, we compared all the sets of stellar masses obtained through these different methods. To ensure consistency and robustness in our comparisons, we used identical WD models and evolutionary tracks across all four methods. The analysis suggests a general consensus among the these methods regarding the masses of pulsating WD with H-rich atmospheres, known as DAV or ZZ Ceti stars, especially for objects with masses below approximately $0.75 M_{\sun}$, although notable disparities emerge for certain massive stars. For pulsating WD stars with He-rich atmospheres, called DBV or V777 Her stars, we find that astrometric masses generally exceed seismological, spectroscopic, and photometric masses. Finally, while there is agreement among the sets of stellar masses for pulsating WDs with C-, O-, and He-rich atmospheres (designated as GW Vir stars), outliers exist where mass determinations by various methods show significant discrepancies.

One-third of Mars' surface has shallow-buried H$_2$O, but it is currently too cold for use by life. Proposals to warm Mars using greenhouse gases require a large mass of ingredients that are rare on Mars' surface. However, we show here that artificial aerosols made from materials that are readily available at Mars-for example, conductive nanorods that are ~9 $\mu$m long-could warm Mars >5 $\times$ 10$^3$ times more effectively than the best gases. Such nanoparticles forward-scatter sunlight and efficiently block upwelling thermal infrared. Similar to the natural dust of Mars, they are swept high into Mars' atmosphere, allowing delivery from the near-surface. For a particle lifetime of 10 years, two climate models indicate that sustained release at 30 liters/sec would globally warm Mars by $\gtrsim$30 K and start to melt the ice. Therefore, if nanoparticles can be made at scale on (or delivered to) Mars, then the barrier to warming of Mars appears to not be as high as previously thought.

This chapter provides an in-depth overview of white dwarfs, the evolutionary terminus of the vast majority of stars. It discusses their discovery, their nature as degenerate objects, their connections to earlier phases of stellar evolution, their subsequent evolution as they gradually cool down, the varied physical conditions from their dense cores to their tenuous atmospheres, some key statistics about the properties of the ever expanding population of known white dwarfs, the diversity of their spectra, the accretion of planetary material, and the presence of magnetic fields. The chapter also highlights the instrumental role of white dwarfs in other areas of astronomy.

The stellar masses of galaxies are measured using integrated light via several methods -- however, few of these methods were designed for low-mass ($M_{\star}\lesssim10^{8}\rm{M_{\odot}}$) "dwarf" galaxies, whose properties (e.g., stochastic star formation, low metallicity) pose unique challenges for estimating stellar masses. In this work, we quantify the precision and accuracy at which stellar masses of low-mass galaxies can be recovered using UV/optical/IR photometry. We use mock observations of 469 low-mass galaxies from a variety of models, including both semi-empirical models (GRUMPY, UniverseMachine-SAGA) and cosmological baryonic zoom-in simulations (MARVELous Dwarfs and FIRE-2), to test literature color-$M_\star/L$ relations and multi-wavelength spectral energy distribution (SED) mass estimators. We identify a list of "best practices" for measuring stellar masses of low-mass galaxies from integrated photometry. These include updated prescriptions for stellar mass based on $g-r$ color and WISE 3.4 $\mu$m luminosity, which are less systematically biased than literature calibrations and can recover true stellar masses of low-mass galaxies with $\sim0.1$ dex precision. When using SED fitting to estimate stellar mass, we find that the form of the assumed star formation history can induce significant biases: parametric SFHs can underestimate stellar mass by as much as $\sim0.4$ dex, while non-parametric SFHs recover true stellar masses with insignificant offset ($-0.03\pm0.11$ dex). However, we also caution that non-informative dust attenuation priors may introduce $M_\star$ uncertainties of up to $\sim0.6$ dex.

The J=1$\rightarrow$0 spectral line of carbon monoxide (CO(1-0)) is the canonical tracer of molecular gas. However, CO(2-1) is frequently used in its place, following the assumption that the higher energy line can be used to infer the CO(1-0) luminosity and molecular gas mass. The use of CO(2-1) depends on a knowledge of the ratio between CO(2-1) and CO(1-0) luminosities, r21. Here we present galaxy-integrated r21 measurements for 122 galaxies spanning stellar masses from 10$^9$ to 10$^{11.5}$ M$_\odot$ and star formation rates (SFRs) from 0.08 to 35 M$_\odot$/yr. We find strong trends between r21 and SFR, SFR surface density, star formation efficiency, and distance from the star formation main sequence (SFMS). We show that the assumption of a constant r21 can introduce biases into the molecular gas trends in galaxy population studies and demonstrate how this affects the recovery of important galaxy scaling relations, including the Kennicutt-Schmidt law and the relation between SFMS offset and star formation efficiency. We provide a prescription which accounts for variations in r21 as a function of SFR and can be used to convert between CO(2-1) and CO(1-0) when only one line is available. Our prescription matches variations in r21 for both AMISS and literature samples and can be used to derive more accurate gas masses from CO(2-1) observations.

The best molecular line lists for astrophysical applications today require both high accuracy of line positions for strong lines as well as high overall completeness. The former is required to enable, for example, molecular detection in high-resolution cross-correlation observations of exoplanets, while completeness is required for accurate spectroscopic and radiative properties over broad temperature and spectral ranges. The use of empirical energies generated with the Marvel procedure is a standard way to improve accuracy; here we explore methods of extending the use of these levels using predicted shifts and isotopologue extrapolation, as well augmenting the levels from other sources such as effective Hamiltonian studies. These methods are used to update ExoMol line lists for the main 24Mg16O and 48Ti16O isotopologues, as well as for 24Mg17O, 24Mg18O, 25Mg16O, 26Mg16O, 46Ti16O, 47Ti16O, 49Ti16O and 50Ti16O; new Marvel results for 51V16O are also presented

The JWST and ALMA have detected emission lines from the ionized interstellar medium (ISM), including [OII], [OIII], and hydrogen Balmer series lines, in some of the first galaxies at z>6. These measurements present an opportunity to better understand galaxy assembly histories and may allow important tests of state-of-the-art galaxy formation simulations. It is challenging, however, to model these lines in their proper cosmological context given the huge dynamic range in spatial scales involved. In order to meet this challenge, we introduce a novel sub-grid line emission modeling framework. The framework uses the high-z zoom-in simulation suite from the Feedback in Realistic Environments (FIRE) collaboration. The line emission signals from HII regions within each simulated FIRE galaxy are modeled using the semi-analytic HIILines code. A machine learning, Mixture Density Network, approach is then used to determine the conditional probability distribution for the line luminosity to stellar-mass ratio from the HII regions around each simulated stellar particle given its age, metallicity, and its galaxy's total stellar mass. This conditional probability distribution can then be applied to predict the line luminosities around stellar particles in lower resolution, yet larger volume cosmological simulations. As an example, we apply this approach to the Illustris-TNG simulations at z=6. The resulting predictions for the [OII], [OIII], and Balmer line luminosities as a function of star-formation rate agree well with current observations. Our predictions differ, however, from related work in the literature which lack detailed sub-grid ISM models. This highlights the importance of our multi-scale simulation modeling framework. Finally, we provide forecasts for future line luminosity function measurements from the JWST and quantify the cosmic variance in such surveys.

We present the results of the Large Binocular Telescope Satellites Of Nearby Galaxies Survey (LBT-SONG) ``Far Sample,'' including survey completeness estimates. We find 10 satellite candidates in the inner virial regions of 13 star-forming galaxies outside the Local Group. The hosts are at distances between $\sim 5-11$ Mpc and have stellar masses in the little explored range of $\sim 5 \times 10^8 - 5\times 10^{10}~\text{M}_{\odot}$. Among the 10 satellite candidates, 3 are new discoveries in this survey. In this paper, we characterize the properties of 8 low-mass satellite candidates, including the 3 new discoveries but excluding 2 well-studied massive satellites. Of the 8 low-mass dwarfs, optical colors from the LBT imaging and measurements in the ultraviolet with GALEX suggest that 2 show signs of active star formation, and 6 are likely quenched (although some may still have H\textsc{i} gas reservoirs). Notably, we report the discovery of an ultrafaint dwarf candidate, NGC 672 dwD, with $\text{M}_{\text{V}} = -6.6$ and an estimated stellar mass of $5.6 \times 10^4 ~\text{M}_{\odot}$ if its association with the host is confirmed. It is spatially coincident with a weak detection of H\textsc{i}, with $\text{M}_{\text{HI}}/\text{M}_{\text{*}} \sim 1$. If confirmed, it would be the least luminous known ultrafaint satellite to be so gas-rich. The prevalence of quenched satellites in our sample suggests there are environmental effects at work in lower mass hosts that are similar to those at play in Milky Way-size hosts, although the preponderance of H\textsc{i} detections is at odds with the paucity of H\textsc{i} detections in Milky Way satellites. By robustly measuring our survey completeness function, we are able to compare our observational results to predictions from theory, finding good agreement with the Cold Dark Matter galaxy evolution paradigm.

We present a numerical discovery that the observable stellar properties of present galaxies retain significant dependences on the primordial density and tidal fields. Analyzing the galaxy catalogs from the IllustrisTNG 300-1 simulations, we first compute the primordial spin factor, $\tau$, defined as the mean degree of misalignments between the principal axes of the initial density and potential hessian tensors at the protogalactic sites. Then, we explore in the framework of Shannon's information theory if and how strongly each of six stellar properties of the present galaxies, namely the stellar sizes, ages, specific star formation rates, optical colors and metallicities, share mutual information with $\tau$, measured at $z=127$. The TNG galaxy samples are deliberately controlled to have no differences in the mass, environmental density and shear distributions and to single out net effects of $\tau$ on each of the galaxy stellar properties. In the higher stellar mass range of $M_{\star}/(h^{-1}\,M_{\odot})\ge 10^{10}$, significant amounts of mutual information with $\tau$ are exhibited by all of the six stellar properties, while in the lower range of $M_{\star}/(h^{-1}\,M_{\odot})< 10^{10}$ only four of the six properties except for the specific star formation rates and colors yield significant signals of $\tau$-dependence. It is also shown that the galaxy stellar sizes, which turn out to be most robustly dependent on $\tau$ regardless of $M_{\star}$, follow a {\it bimodal} Gamma distribution, the physical implication of which is discussed.

We put forward a primordial scenario to alleviate cosmological tensions, i.e. Hubble ($H_0$) tension and $ S_8 $ tension. Based on flat $\Lambda$CDM, the Bounce-Inflation (BI) scenario gives the results that $ H_0 = 68.60^{+0.40}_{-0.45} \, \text{km}/\text{s}/\text{Mpc}$, $ S_8 = 0.806 \pm 0.011 $ by using \texttt{Planck 2018} data sets and $ H_0 = 68.96 \pm 0.38 \, \text{km}/\text{s}/\text{Mpc}$, $ S_8 = 0.797\pm 0.010 $ by using \texttt{Planck 2018} + \texttt{SPT3G} data sets. These reduce the cosmological tensions slightly. We also take an extended $\Lambda$CDM model into account, $\Lambda$CDM (BI)+$A_L$, where $ A_L $ is the gravitational lensing amplitude. The results are $ H_0 = 69.38 \pm 0.49 \, \text{km}/\text{s}/\text{Mpc}$, $ S_8 = 0.774 \pm 0.014 $ fitted by \texttt{Planck 2018} data sets and $ H_0 = 69.49 \pm 0.45 \, \text{km}/\text{s}/\text{Mpc}$, $ S_8 = 0.771^{+0.013}_{-0.012} $ fitted by \texttt{Planck 2018} + \texttt{SPT3G} data sets, which reduce the Hubble tension to $\sim 3\sigma $ level and show no $S_8 $ tension. The $A_L \approx 1.1$ is smaller than the result of the inflation scenario with a constraint of \texttt{Planck 2018} data sets. Besides, the spectral index of the bounce-inflation scenario $ n_s $ is about $ 0.98 $, with a trend to the Harrison-Zel'dovich spectrum.

In the single-field model, the preheating process occurs through self-resonance of inflaton field. We study the nonlinear structures generated during preheating in the $\alpha$-attractor models and monodromy models. The potentials have a power law form $\propto\left|\phi\right|^{2n}$ near the origin and a flat region away from bottom, which are consistent with current cosmological observations. The Floquet analysis shows that potential parameters in monodromy model have a significant influence on the region of resonance bands. The analytical oscillons solution for the $\alpha$-attractor T model with parameter $n=1$ is derived using the small amplitude analysis method. Besides we investigate the formation of nonlinear structures, the equation of state and the energy transfer through the (3+1) dimensional lattice simulation. We find that the symmetric T potential and the asymmetric E potential in the $\alpha$-attractor models have similar nonlinear dynamics. And the potential parameter $n$ in monodromy model significantly influences the lifetime of transients, whereas the parameter $q$ exerts minimal impact on the nonlinear dynamics.

The carbon footprint of astronomical research is an increasingly topical issue. From a comparison of existing literature, we infer an annual per capita carbon footprint of several tens of tonnes of CO$_2$ equivalents for an average person working in astronomy. Astronomical observatories contribute significantly to the carbon footprint of astronomy, and we examine the related sources of greenhouse gas emissions as well as lever arms for their reduction. Comparison with other scientific domains illustrates that astronomy is not the only field that needs to accomplish significant carbon footprint reductions of their research facilities. We show that limiting global warming to 1.5°C or 2°C implies greenhouse gas emission reductions that can only be reached by a systemic change of astronomical research activities, and we argue that a new narrative for doing astronomical research is needed if we want to keep our planet habitable.

We study the propagation of electromagnetic waves in tenuous plasmas, where the wave frequency, $\omega_0$, is much larger than the plasma frequency, $\omega_{\rm P}$. We show that in pair plasmas nonlinear effects are weak for $a_0 \ll \omega_0/\omega_{\rm P}$, where $a_0$ is the wave strength parameter. In electron-proton plasmas a more restrictive condition must be satisfied, namely either $a_0\ll 1/\omega_{\rm P}\tau_0$, where $\tau_0$ is the duration of the radiation pulse, or $a_0\ll 1$. We derive the equations that govern the evolution of the pulse in the weakly nonlinear regime. Our results have important implications for the modeling of fast radio bursts. We argue that: (i) Millisecond duration bursts with a smooth profile must be produced in a proton-free environment, where nonlinear effects are weaker. (ii) Propagation through an electron-proton plasma near the source can imprint a sub-microsecond variability on the burst profile.

If ultralight boson fields exist, then vacuum misalignment populates them with nonzero relic abundance. For a broad range of particle mass $m$ the field condenses into fuzzy cores in massive galaxies. We use numerical simulations to test this idea, extending previous work (Blum and Teodori 2021) and focusing on ultralight dark matter (ULDM) that makes-up a subdominant fraction of the total dark matter density, consistent with observational constraints. Our simulations mimic galactic halos and explore different initial conditions and levels of sophistication in the modeling of the halo potential. For $m\sim10^{-25}$ eV ULDM cores act as approximate internal mass sheets in strong gravitational lensing, and could first be detected as an $H_0$ bias in cosmography: a scenario we dub AxionH0graphy. The mass sheet degeneracy is broken by finite core radius and by the dynamical displacement of cores from the halo center of mass, which introduce imaging distortions and restrict the $H_0$ bias limit of AxionH0graphy to $m\lesssim5\times10^{-25}$ eV. Cosmological simulations are called for to sharpen the predicted connection between the amplitude of ULDM galactic cores and the ULDM cosmological fraction.

The threat posed to humanity by global warming has led scientists to question the nature of their activities and the need to reduce the greenhouse gas emissions from research. Until now, most studies have aimed at quantifying the carbon footprints and relatively less works have addressed the ways GHG emissions can be significantly reduced. A factor two reduction by 2030 implies to think beyond increases in the efficacy of current processes, which will have a limited effect, and beyond wishful thinking about large new sources of energy. Hence, choices among research questions or allocated means within a given field will be needed. They can be made in light of the perceived societal utility of research activities. Here, we addressed the question of how scientists perceive the impact of GHG reduction on their discipline and a possible trade-off between the societal utility of their discipline and an acceptable level of GHG emissions. We conducted 28 semi-directive interviews of French astrophysicists from different laboratories. Our most important findings are that, for most researchers, astronomy is considered to have a positive societal impact mainly regarding education but also because of the fascination it exerts on at least a fraction of the general public. Technological applications are also mentioned but with relatively less emphasis. The reduction of GHG emissions is believed to be necessary and most often reductions within the private-sphere have been achieved. However, the question of community-wide reductions in astrophysics research, and in particular the possible reductions of large facilities reveals much more contrasted opinions.

Exploding granules on the solar surface play a major role in the dynamics of the outer part of the convection zone, especially in the diffusion of magnetic field. We aimed at developing an automated procedure able to investigate the location and evolution of exploding granules over the solar surface and to get rid of visual detection. We used sequences of observations of intensity and Doppler velocity, as well as magnetograms, provided by the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory. The automated detection of the exploding granules is performed by applying criteria on either three or two parameters: the granule area, the amplitude of the velocity field divergence, and, at the disc centre, the radial Doppler velocity. Our analyses showed that granule area and divergence amplitudes are sufficient to detect the largest exploding granules, we thus can automatically detect them, not only at the disc centre, but on the whole solar surface. Using a 24-hour-long observation sequence, we demonstrated the important contribution of the most dynamic exploding granules in the diffusion of the magnetic field in the quiet Sun. Indeed, we showed that the most intense exploding granules are sufficient to build a large part of the photospheric network. We also applied our procedure on Hinode observations to locate the exploding granules relative to Tree of Fragmenting Granules (TFG). We concluded that, during a first phase of about 300 minutes after the birth of a TFG, exploding granules are preferentially located on its edge. Finally, we also showed that the distribution of exploding granules is homogeneous (at the level of our measurement errors) over the solar surface without significant dependency with latitude.

The origin of the astrophysical neutrino flux discovered by IceCube remains largely unknown. Several individual neutrino source candidates were observed. Among them is the gamma-ray flaring blazar TXS 0506+056. A similar coincidence of a high-energy neutrino and a gamma-ray flare was found in blazar PKS 0735+178. By modeling the spectral energy distributions of PKS 0735+178, we expect to investigate the physical conditions for neutrino production during different stages of the source activity. We analyze the multi-wavelength data during the selected periods of time. Using numerical simulations of radiation processes in the source, we study the parameter space of one-zone leptonic and leptohadronic models and find the best-fit solutions that explain the observed photon fluxes. We show the impact of model parameter degeneracy on the prediction of the neutrino spectra. We show that the available mutli-wavelength data are not sufficient to predict the neutrino spectrum unambiguously. Still, under the condition of maximal neutrino flux, we propose a scenario in which 0.2 neutrino events are produced during the 50 days flare.

The BEBOP (Binaries Escorted By Orbiting Planets) survey is a search for circumbinary planets using the radial velocity spectrographs HARPS and SOPHIE, currently focusing on single-lined binaries with a mass ratio $<0.3$. Circumbinary systems are an important testing ground for planet formation theories as the dynamically complex influence of the binary makes planet formation and survival more difficult. Here we present the results of the survey so far including: confirmed planets such as BEBOP-1c the first circumbinary planet detected in radial velocity; the status of our observations; and preliminary occurrence rates. We compare the early results of the radial velocity survey to the population of circumbinary planets discovered in transit, and suggest that there may be a population of inflated planets close to the inner binary which are detectable in transit but more difficult in radial velocity. Using time-lag tidal theory, we show that this inflation is unlikely caused by tides.

The Zwicky Transient Facility SN Ia Data Release 2 (ZTF SN Ia DR2) contains more than 3,000 Type Ia supernovae (SNe Ia), providing the largest homogeneous low-redshift sample of SNe Ia. Having at least one spectrum per event, this data collection is ideal for large-scale statistical studies of the photometric, spectroscopic and host-galaxy properties of SNe Ia, particularly of the more rare "peculiar" subclasses. In this paper, we first present the method we developed to spectroscopically classify the SNe in the sample, and the techniques we used to model their multi-band light curves and explore their photometric properties. We then show a method to distinguish between the "peculiar" subtypes and the normal SNe Ia. We also explore the properties of their host galaxies and estimate their relative rates, focusing on the "peculiar" subtypes and their connection to the cosmologically useful SNe Ia. Finally, we discuss the implications of our study with respect to the progenitor systems of the "peculiar" SN Ia events.

A solitonic model of the early universe is introduced by employing the Double-Sine-Gordon (DSG) potential. The model predicts the appropriate number of e-foldings ($N_e$) required for favored inflation and is an advantage for the model in addressing the flatness, horizon, and magnetic monopole problems. Compatibility of the model with observations, including the Planck $2018$ data \cite{Akrami et al. (2020)} and the Planck $2018$ data+BK$18$+BAO \cite{Ade et al. (2021)} paves the way to estimate the model's free parameters. The results generate acceptable and proper values for the spectral index ($n_s$) and the tensor-to-scalar ratio ($r$) in agreement with the Planck $2018$ data \cite{Akrami et al. (2020)} and the Planck $2018$ data+BK$18$+BAO \cite{Ade et al. (2021)}. Correspondingly, a consistent description of the reheating era is obtained, yielding positive reheating number of e-foldings ($N_{\mathrm{reh}}$) and reheating final temperature ($T_{\mathrm{reh}}$) from $10^{-2}$ GeV to $10^{16}$ GeV. Overall, the model seems viable at the inflationary and reheating eras.

The origin and evolution of organic molecules represent a pivotal issue in the fields of astrobiology and astrochemistry, potentially shedding light on the origins of life. The James Webb Space Telescope (JWST), with its exceptional sensitivity and spectral resolution, is well suitable to observe molecules such as methane ($\rm CH_4$). Our analysis focused on the distribution of $\rm CH_4$, $\rm CO_2$, $\rm H_2O$, $\rm{CH_3OH+NH_4^+}$ ice and silicate absorption dips at approximately 7.7, 15.0, 6.0, 6.7 and 10.0 micrometres in two protostars: IRAS 16253-2429 and IRAS 23385+6053. We extract the $\rm CH_4$, $\rm CO_2$, $\rm H_2O$, $\rm{CH_3OH+NH_4^+}$ ice equivalent width (EW) maps and silicate extinction maps of the two sources. Our results reveal that the spatial distribution of $\rm CH_4$ in the protostellar system IRAS 16253-2429 closely mirrors that of its $\rm CO_2$ ice, forming a surrounded distribution that encircles the central protostar. This alignment suggests a common formation mechanism and subsequent trapping within the protostellar envelope, which is consistent with the "Classical" dark-cloud chemistry with ion-molecule reaction. In contrast, the spatial distributions of various molecules in the system IRAS 23385+6053 exhibit low similarities, which may be attributed to the dynamic influences of outflows or accretion processes. These discrepancies highlight the complex interplay between physical processes and chemical evolution in protostellar environments.

Orbiting space objects have become in the last decade a major nuisance impacting ground astronomy and orbiting space assets, from observatories to satellites and space stations. In particular with the rise of the satellite population in Low Earth Orbits (LEOs), space objects are becoming an even bigger threat and a strong problem to astronomical observations. To tackle these threats several coordinated surveillance networks composed of dedicated sensors (telescopes, radars and laser ranging facilities) track and survey space objects, from debris to active satellites. As part of the European Space Surveillance \& Tracking (EU-SST) network, Portugal is developing the PAmpilhosa da Serra Space Observatory (PASO), with both radio and optical telescopes dedicated to the Space Situational Awareness (SSA) domain, deployed at a Dark Sky destination. To optimize telescope survey time, we developed {\tt{CLOWN}} (CLOud Watcher at Night), an application interface that automatically monitors clouds in real time. This software can correctly trace clouds positions in the sky, provides accurate pointing information to the observation planning of the optical telescope to avoid cloudy areas. {\tt{CLOWN}} only requires the use of an all-sky camera, which is already a norm in observatories with optical telescopes and can be used with any camera, including those for which no information about its model specification do exist. {\tt{CLOWN}} does not require great computing power and it does not require the installation of additional equipment. {\tt{CLOWN}} results are very promising and confirm that the app can correctly identify clouds in a variety of different conditions and cloud types.

In the near-infrared wavelength regime, atmospheric turbulence fluctuates at a scale of a few milliseconds, and its precise control requires the use of extreme adaptive optics (XAO) systems equipped with fast and sensitive detectors operating at kHz speeds. The C-RED One cameras developed by First Light Imaging (FLI), based on SAPHIRA detectors made of HgCdTe e-APD array sensitive to 0.8-2.5 $\mu$m light, featuring a 320x256 pixels with 24 $\mu$m pitch, offering sub-electron readout noise and the ability to read subarrays, at frame-rates of up to few 10-kHz, are state-of-the-art for XAO wavefront sensing. The Observatory of Geneva purchased two C-RED One cameras identified as necessary for RISTRETTO (a proposed high-contrast high-resolution spectrograph for the VLT) and SAXO+ (an upgrade of the VLT/SPHERE XAO system) projects. We present a comprehensive characterization and comparative analysis of both the cameras. We present test results examining key noise contributors, including readout noise, detector bias, etc. And we also study their temporal variability. Additionally, we assess the conversion gain and the avalanche gain calibration of the detector. We also study the evolution some of these parameters over time.

The RISTRETTO instrument, a proposed visible high-contrast, high-resolution spectrograph for the VLT, has the primary science goal of detecting reflected light from nearby exoplanets and characterizing their atmospheres. Specifically, it aims to atmospherically characterize Proxima b, our closest temperate rocky exoplanet, located $37 mas$ from its host star, corresponding to $2\lambda/D$ at $\lambda=750 nm$. To achieve this goal, a raw contrast of less than $10^{-4}$ at $2\lambda/D$ and a Strehl ratio greater than 70% are required, necessitating an extreme adaptive optics system (XAO) for the spectrograph. To meet the performance requirements for RISTRETTO, high sensitivity to low-order wavefront aberrations and petal modes is essential. Therefore, unmodulated Pyramid wavefront sensors (PWFS) and Zernike wavefront sensors (ZWFS) are under consideration. However, these sensors exhibit non-linearities and have a limited dynamic range, requiring different strategies to optimize their performance. The dynamic range of the sensors increases at longer wavelengths. Thus, in this study, we compare the performance of the 3-sided unmodulated PWFS, the 4-sided unmodulated PWFS, and the Zerniike WFS at different wavelengths in the visible and near-infrared regime.

In this letter we investigate the origin of the Oosterhoff dichotomy, considering recent discoveries related to several ancient merging events of external galaxies with the Milky Way (MW). In particular, we aim to clarify if the subdivision in Oosterhoff type of Galactic Globular Clusters (GGCs) and field RR Lyrae (RRLs) could be traced back to one or more ancient galaxies that merged with the MW in its past. To this purpose, we first explored the association of GGCs with the past merging events according to different literature studies. Subsequently we compiled positions, proper motions and radial velocity for 10,138 field RRLs variables from the $Gaia$ Data Release 3. To infer the distances, we adopted the $M_G$--[Fe/H] relation, with [Fe/H] values estimated through empirical relationships involving the individual periods and Fourier parameters. We then calculated the orbits and the integrals of motions (IoM) using the Python library Galpy for the whole sample. By comparing the location of the field RRLs in the energy-angular momentum diagram with that of the GGCs we assign their likely origin. Finally, we discriminate from the $Gaia$ G-band light curves the Oosterhoff type of our sample of RRL stars based on their location in the Bailey diagram. The analysis of the Bailey diagrams for Galactic RRLs stars and GGCs associated with \textit{In-Situ} vs \textit{Accreted} halo origin shows remarkable differences. The \textit{In-Situ} sample displays a wide range of metallicities with a continuous distribution and no sign of Oosterhoff dichotomy. Conversely, the \textit{Accreted} RRLs clearly shows the Oosterhoff dichotomy and a significantly smaller dispersion in metallicity. Our results suggest that the Oosterhoff dichotomy was imported into the MW by the merging events that shaped the Galaxy.

The Sun's global inertial modes are very sensitive to the solar differential rotation and to properties of the deep solar convection zone which are currently poorly constrained. These properties include the superadiabatic temperature gradient, the latitudinal entropy gradient, and the turbulent viscosity. The inertial modes also play a key role in controlling the Sun's large-scale structure and dynamics, in particular the solar differential rotation. This paper summarizes recent observations and advances in the (linear and nonlinear) modeling of the solar inertial modes.

We present the first homogeneous release of several thousand Type Ia supernovae (SNe Ia), all having spectroscopic classification, and spectroscopic redshifts for half the sample. This release, named the "DR2", contains 3628 nearby (z < 0.3) SNe Ia discovered, followed and classified by the Zwicky Transient Facility survey between March 2018 and December 2020. Of these, 3000 have good-to-excellent sampling and 2667 pass standard cosmology light-curve quality cuts. This release is thus the largest SN Ia release to date, increasing by an order of magnitude the number of well characterized low-redshift objects. With the "DR2", we also provide a volume-limited (z < 0.06) sample of nearly a thousand SNe Ia. With such a large, homogeneous and well controlled dataset, we are studying key current questions on SN cosmology, such as the linearity SNe Ia standardization, the SN and host dependencies, the diversity of the SN Ia population, and the accuracy of the current light-curve modeling. These, and more, are studied in detail in a series of articles associated with this release. Alongside the SN Ia parameters, we publish our force-photometry gri-band light curves, 5138 spectra, local and global host properties, observing logs, and a python tool to ease use and access of these data. The photometric accuracy of the "DR2" is not yet suited for cosmological parameter inference, which will follow as "DR2.5" release. We nonetheless demonstrate that the multi-thousand SN Ia Hubble Diagram has a typical 0.15 mag scatter.

This paper presents a comprehensive analysis of RR Lep and BF Vel, two short-period semi-detached oscillating Algols (oEA stars), which are shown to be triple systems. Spectral types of their primaries were determined and radial velocities calculated from spectra observed with the Australian National University's 2.3 m telescope and Wide Field Spectrograph. Spectra of the Na I D doublet confirmed the presence of tertiary components which were apparent in the broadening function analyses and, with H_a spectra during primary eclipses, indicated chromospherical activity in their secondaries. Ground-based telescopes were used for observations in several pass bands for photometric analyses. These data were complemented by data from the TESS mission to enable the modelling of the light curves, followed by a detailed analysis of pulsations. Eclipse-timing variation (ETV) analyses of both systems were used to determine the most likely mechanisms modulating the orbital period. We found mass values M1 = 2.9 M_sun and M2 = 0.75 M_sun for the components of RR Lep, and M1 = 1.93 M_sun and M2 = 0.97 M_sun for those of BF Vel. By integrating information from photometry, spectroscopy and ETV analysis, we found that tertiary components revolve around both systems. The primary star of RR Lep pulsates in 36 frequencies, of which five were identified as independent modes, with the dominant one being 32.28 d^-1. The pulsating component of BF Vel oscillates in 37 frequencies, with the frequency 46.73 d^-1 revealed as the only independent mode. For both systems, many frequencies were found to be related to the orbital frequency. Their physical properties were compared with other oEA stars in Mass-Radius and H-R diagrams, and the pulsational properties of their delta Sct components were compared with currently known systems of this type within the orbital-pulsation period and logg-pulsation period diagrams.

The distribution of different types of atmospheres and surfaces on rocky planets is one of the major questions in exoplanet astronomy, but there are currently no published unambiguous detections of atmospheres on any rocky exoplanets. The MIRI instrument on JWST can measure thermal emission from tidally locked rocky exoplanets orbiting small, cool stars. This emission is a function of their surface and atmospheric properties, potentially allowing the detection of atmospheres. One technique is to measure day-side emission to search for lower thermal emission than expected for a black-body planet due to atmospheric absorption features. Another technique is to measure phase curves of thermal emission to search for night-side emission due to atmospheric heat redistribution. In this work we compare strategies for detecting atmospheres on rocky exoplanets using these techniques. We simulate secondary eclipse and phase curve observations in the MIRI F1500W and F1280W filters, for a range of surfaces and atmospheres on thirty exoplanets selected for their F1500W signal-to-noise ratio. Our results show that secondary eclipse observations are highly degenerate between surfaces and atmospheres, given the wide range of potential surface albedos. We also show that thick atmospheres can support emission consistent with a black-body planet in these filters. These two results make it difficult to unambiguously detect or rule out atmospheres using their photometric day-side emission, except in a subset of CO$_{2}$-dominated atmospheres. We suggest that an F1500W phase curve could instead be observed for a similar sample of planets, allowing the unambiguous detection of atmospheres by night-side emission.

We present a procedure for calculating the heating of, and the infrared emission from, dust in a homogeneous spherical shell surrounded by a spherically symmetric source of radiation. The results are applicable to newly formed dust either in supernova ejecta or in the circumstellar medium that has been swept up by the expanding shock wave. They can also be applied to the heating and IR emission from dust in clumps or clouds embedded in a homogeneous radiation field.

As wavefront quality demands tighten on space systems for applications such as astronomy and laser communication, mounting small optics such that the wavefront is undisturbed, positioning is adjustable and the design is producible, while surviving harsh space environments, is a continuing challenge. We designed multiple candidate flexure mounts to support small optics (up to 50 mm diameter, and over 100 grams) to survive the qualification and acceptance tests of small spacecraft and units as defined in ISO 19683 and a mounting structure which is adjustable in decenter [+/-0.5mm], tip/tilt +/-0.5deg, and piston [+/-0.25mm]. We will present design details along with measurements showing less than approximately lambda/10 wavefront contribution from the optic bonding process, along with thermal and multi-axis vibration test data showing the mounted optics survived the acceptance testing loads and are suitable for operation in a wide range of harsh environments.

Neutrino flavor instabilities appear to be omnipresent in dense astrophysical environments, thus presenting a challenge to large-scale simulations of core-collapse supernovae and neutron star mergers (NSMs). Subgrid models offer a path forward, but require an accurate determination of the local outcome of such conversion phenomena. Focusing on "fast" instabilities, related to the existence of a crossing between neutrino and antineutrino angular distributions, we consider a range of analytical mixing schemes, including a new, fully three-dimensional one, and also introduce a new machine learning (ML) model. We compare the accuracy of these models with the results of several thousands of local dynamical calculations of neutrino evolution from the conditions extracted from classical NSM simulations. Our ML model shows good overall performance, but struggles to generalize to conditions from a NSM simulation not used for training. The multidimensional analytic model performs and generalizes even better, while other analytic models (which assume axisymmetric neutrino distributions) do not have reliably high performances, as they notably fail as expected to account for effects resulting from strong anisotropies. The ML and analytic subgrid models extensively tested here are both promising, with different computational requirements and sources of systematic errors.

Several recurrent X-class flares from Active Region (AR) 13664 have triggered a severe G5-class geomagnetic storm between May 10 and 11, 2024. The morphology and compactness of this AR closely resemble the active region responsible for the famous Carrington Event of 1859. Although the induced geomagnetic currents produced a value of the Dst index, probably, an order of magnitude weaker than that of the Carrington Event, the characteristics of AR 13664 warrant special attention. Understanding the mechanisms of magnetic field emergence and transformation in the solar atmosphere that lead to the formation of such an extensive, compact and complex AR is crucial. Our analysis of the emerging flux and horizontal motions of the magnetic structures observed in the photosphere reveals the fundamental role of a sequence of emerging bipoles at the same latitude and longitude, followed by converging and shear motions. This temporal order of processes frequently invoked in magnetohydrodynamic models - emergence, converging motions, and shear motions - is critical for the storage of magnetic energy preceding strong solar eruptions that, under the right timing, location and direction conditions, can trigger severe space weather events at Earth.

White dwarfs are stellar remnants devoid of a nuclear energy source, gradually cooling over billions of years and eventually freezing into a solid state from the inside out. Recently, it was discovered that a population of freezing white dwarfs maintains a constant luminosity for a duration comparable to the age of the universe, signaling the presence of a powerful yet unknown energy source that inhibits the cooling. For certain core compositions, the freezing process is predicted to trigger a solid-liquid distillation mechanism, due to the solid phase being depleted in heavy impurities. The crystals thus formed are buoyant and float up, thereby displacing heavier liquid downward and releasing gravitational energy. Here we show that distillation interrupts the cooling for billions of years and explains all the observational properties of the unusual delayed population. With a steady luminosity surpassing that of some main-sequence stars, these white dwarfs defy their conventional portrayal as dead stars. Our results highlight the existence of peculiar merger remnants and have profound implications for the use of white dwarfs in dating stellar populations.

Ultra-low mass primordial black holes (PBH), briefly dominating the expansion of the universe, would leave detectable imprints in the secondary stochastic gravitational wave background (SGWB). Such a scenario leads to a characteristic doubly peaked spectrum of SGWB and strongly depends on the Hawking evaporation of such light PBHs. However, these observable signatures are significantly altered if the memory burden effect during the evaporation of PBHs is taken into account. We show that for the SGWB induced by PBH density fluctuations, the memory burden effects on the Hawking evaporation of ultra-low mass PBHs can mimic the signal arising due to the non-standard reheating epoch before PBH domination. Finally, we point out that this degeneracy can be broken by the simultaneous detection of the first peak in the SGWB, which is typically induced by the inflationary adiabatic perturbations.

Light-matter interactions lie at the heart of our exploration of exoplanetary atmospheres. Interpreting data obtained by remote sensing is enabled by meticulous, time- and resource-consuming work aiming at deepening our understanding of such interactions (i.e., opacity models). Recently, \citet{Niraula2022} pointed out that due primarily to limitations on our modeling of broadening and far-wing behaviors, opacity models needed a timely update for exoplanet exploration in the JWST era, and thus argued for a scalable approach. In this Letter, we introduce an end-to-end solution from ab initio calculations to pressure broadening, and use the perturbation framework to identify the need for precision to a level of $\sim$10\%. We focus on the CO$_2$-H$_2$ system as CO$_2$ presents a key absorption feature for exoplanet research (primarily driven by the observation of gas giants) at $\sim$4.3$\mu$m and yet severely lack opacity data. We compute elastic and inelastic cross-sections for the collision of {ortho-}H$_2$ ~with CO$_2$, in the ground vibrational state, and at the coupled-channel fully converged level. For scattering energies above $\sim$20~cm$^{-1}$, moderate precision inter-molecular potentials are indistinguishable from high precision ones in cross-sections. Our calculations agree with the currently available measurement within 7\%, i.e., well beyond the precision requirements. Our proof-of-concept introduces a computationally affordable way to compute full-dimensional interaction potentials and scattering quantum dynamics with a precision sufficient to reduce the model-limited biases originating from the pressure broadening and thus support instrument-limited science with JWST and future missions.