Papers for Wednesday, Mar 06 2024

We analyze the OVI content and kinematics for 126 $z < 1$ HI-selected absorbers for which the metallicities of their cool photoionized phase have been determined. We separate the absorbers into 100 strong Lya forest systems (SLFSs with $15 \lesssim$ logN(HI) $< 16.2$) and 26 partial Lyman Limit systems (pLLSs with $16.2 \leq$ logN(HI) $\leq 17.2$). The sample is drawn from the COS CGM Compendium (CCC) of Lehner et al. and has OVI coverage in $S/N \geq 8$ HST/COS G130M/G160M QSO spectra, yielding a $2\sigma$ completeness level of logN(OVI) $\geq 13.6$. There are significant differences in the OVI detection rates between low-metal (LM; [X/H] $\leq -1.4$) SLFSs and high-metal (HM; [X/H] $> -1.4$) SLFSs, $\sim$15\% versus $\sim$60%, respectively. The OVI frequency for the HM and LM pLLSs is, however, similar $\sim$60%. The SLFSs and pLLSs with no OVI are consistent with gas being in a single-phase, while those with OVI trace multiphase gas. We find that the OVI velocity widths and column densities have different distributions in LM and HM gas. We observe a strong correlation between OVI column density and metallicity. The strongest (logN(OVI) $\gtrsim 14$) and broadest OVI absorbers are nearly systematically found to be associated with HM gas, while weaker OVI absorbers are found in both LM and HM HI-bearing gas. From comparisons with galaxy and OVI surveys, we conclude absorbers with logN(OVI) $\gtrsim 14$ most likely arise in the circumgalactic medium (CGM) of star-forming galaxies, with the broadest and strongest possibly tracing galaxy outflows. Absorbers with weak OVI most likely trace the extended CGM or intergalactic medium (IGM), while those without OVI in all likelihood originate in the IGM.

This paper presents a study of the impact of supermassive black hole (SMBH) feedback on dark matter (DM) halos in numerical NIHAO simulations of galaxies. In particular, the amount of DM displaced via active galactic nuclei (AGN) feedback and the physical scale over which AGN feedback affects the DM halo are quantified by comparing NIHAO simulations with and without AGN feedback. NIHAO galaxies with $\log(M_*/M_{\rm \odot})\geq 10.0$ show a growing central DM suppression of 0.2 dex (~40%) from z = 1.5 to the present relative to noAGN feedback simulations. The growth of the DM suppression is related to the mass evolution of the SMBH and the gas mass in the central regions. For the most massive NIHAO galaxies $\log(M_*/M_{\rm \odot}) > 10.5$, partially affected by numerical resolution, the central DM suppression peaks at z = 0.5, after which halo contraction overpowers AGN feedback due a shortage of gas and, thus, SMBH growth. The spatial scale, or ``sphere of influence,'' over which AGN feedback affects the DM distribution decreases as a function of time for MW-mass galaxies (from ~16 kpc at z = 1.5 to ~7.8 kpc at z = 0) as a result of halo contraction due to stellar growth. For the most massive NIHAO galaxies, the size of the sphere of influence remains constant (~$16 kpc) for z > 0.5 owing to the balance between AGN feedback and halo contraction.

We report the discovery of a hot Jupiter candidate orbiting HS Psc, a K7 ($\approx$0.7 $M_\odot$) member of the $\approx$130 Myr AB Doradus moving group. Using radial velocities over 4 years from the Habitable-zone Planet Finder spectrograph at the Hobby-Eberly Telescope, we find a periodic signal at $P_b = 3.986_{-0.003}^{+0.044}$ d. A joint Keplerian and Gaussian process stellar activity model fit to the RVs yields a minimum mass of $m_p \sin i = 1.5_{-0.4}^{+0.6}$ $M_\mathrm{Jup}$. The stellar rotation period is well constrained by the Transiting Exoplanet Survey Satellite light curve ($P_\mathrm{rot} = 1.086 \pm 0.003$ d) and is not an integer harmonic nor alias of the orbital period, supporting the planetary nature of the observed periodicity. HS Psc b joins a small population of young, close-in giant giant planet candidates with robust age and mass constraints and demonstrates that giant planets can either migrate to their close-in orbital separations by 130 Myr or form $in \; situ$. Given its membership in a young moving group, HS Psc represents an excellent target for follow-up observations to further characterize this young hot Jupiter, refine its orbital properties, and search for additional planets in the system.

We present ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early-time ($\delta t < 2$ days) spectra show transient, narrow emission lines from shock ionization of confined ($r < 10^{15}$ cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) of HI, He I/II, C III/IV, and N III/IV/V from the CSM persist on a characteristic timescale ($t_{\rm IIn}$) that marks a transition to a lower-density CSM and the emergence of Doppler-broadened features from the fast-moving SN ejecta. Our sample, the largest to date, consists of 39 SNe with early-time IIn-like features in addition to 35 "comparison" SNe with no evidence of early-time IIn-like features, all with ultraviolet observations. The total sample consists of 50 unpublished objects with 474 previously unpublished spectra and 50 multiband light curves, collected primarily through the Young Supernova Experiment and Global Supernova Project collaborations. For all sample objects, we find a significant correlation between peak ultraviolet brightness and both $t_{\rm IIn}$ and the rise time, as well as evidence for enhanced peak luminosities in SNe II with IIn-like features. We quantify mass-loss rates and CSM density for the sample through matching of peak multiband absolute magnitudes, rise times, $t_{\rm IIn}$ and optical SN spectra with a grid of radiation hydrodynamics and non-local thermodynamic equilibrium (nLTE) radiative-transfer simulations. For our grid of models, all with the same underlying explosion, there is a trend between the duration of the electron-scattering broadened line profiles and inferred mass-loss rate: $t_{\rm IIn} \approx 3.8[\dot{M}/(0.01 \textrm{M}_{\odot} \textrm{yr}^{-1})]$ days.

We present results of a continuation of our Transiting Exoplanet Survey Satellite (TESS) search for short-period pulsations in compact stellar objects observed during Years 2 and 4 of the TESS mission that targeted the northern ecliptic hemisphere. For many of the targets, we exploit unpublished spectroscopic data to confirm or determine the object's spectral classification. From the TESS photometry, we identify 50 short-period hot-subdwarf pulsators, including 35 sdB and 15 sdOB stars. The sample contains 26 pulsators not known before the TESS mission. Nine stars show signals at both low and high frequencies, and are therefore ``hybrid'' pulsators. For each pulsator, we report the list of prewhitened frequencies and we show amplitude spectra calculated from the TESS data. We attempt to identify possible multiplets caused by stellar rotation, and we report five candidates with rotation periods between 11 and 46d. Having the search for p-mode pulsating hot subdwarfs in TESS Sectors 1 - 60 done, we discuss the completeness of the study, as well as instability strip and the evolutionary status of the stars we found. We also compare the distribution of pulsation periods as a function of effective temperature and surface gravity with theoretical predictions.

We present CO ($J = 1-0$) multi-line observations toward the L914 dark cloud in the vicinity of the Cygnus X region, using the 13.7 m millimeter telescope of the Purple Mountain Observatory (PMO). The CO observations reveal in the L914 cloud a long filament with an angular length of $\sim 3.\!\!^\circ 6$, corresponding to approximately $\rm 50~pc$ at the measured distance of $\sim\rm 760~pc$. Furthermore, a group of hair-like striations are discovered in the two subregions of the L914 cloud, which are connected with the dense ridge of the filament. These striations display quasi-periodic characteristics in both the CO intensity images and position-velocity diagrams. Two of the striations also show increasing velocity gradients and dispersions toward the dense ridge, which could be fitted by accretion flows under gravity. Based on the $Planck$ 353 GHz dust polarization data, we find that the striations are well aligned with the magnetic fields. Moreover, both the striations and magnetic fields are perpendicular to the dense ridge, which constructs a bimodal configuration. Using the classic method, we estimate the strength of magnetic field, and further evaluate the relative importance of gravity, turbulence and magnetic field, and find that the L914 cloud is strongly magnetized. Our results suggest that magnetic fields play an important role in the formation of filamentary structures by channelling the material along the striations toward the dense ridge. The comparison between the observations and simulations suggests that striations could be a product of the magnetohydrodynamic (MHD) process.

The gravitational wave detectors have unveiled a population of massive black holes that do not resemble those observed in the Milky Way. They may have formed due to the evolution of massive low-metallicity stars, dynamical interactions in dense stellar environments, or density fluctuations in the very early Universe (primordial black holes). If the latter hypothesis is correct, primordial black holes should comprise from several to 100% of dark matter to explain the black hole merger rates observed by gravitational wave detectors. If such black holes existed in the Milky Way dark matter halo, they would cause long-timescale gravitational microlensing events lasting years. Here, we present the results of the search for the long-timescale microlensing events among the light curves of 78.7 million stars located in the Large Magellanic Cloud (LMC) that were monitored for 20 years (2001-2020) by the Optical Gravitational Lensing Experiment (OGLE) survey. We did not find any events with timescales longer than one year. The properties of all thirteen microlensing events with timescales shorter than one year detected by OGLE toward the LMC can be explained by astrophysical objects located either in the LMC itself or in the Milky Way disk, without the need to invoke dark matter in the form of compact objects. We find that compact objects in the mass range from $1.8 \times 10^{-4}\,M_{\odot}$ to $6.3\,M_{\odot}$ cannot compose more than 1% of dark matter, and compact objects in the mass range from $1.3 \times 10^{-5}\,M_{\odot}$ to $860\,M_{\odot}$ cannot make up more than 10% of dark matter. This conclusively rules out primordial black hole mergers as a dominant source of gravitational waves.

Low-mass galaxies can significantly contribute to reionization due to their potentially high Lyman continuum (LyC) escape fraction and relatively high space density. We present a constraint on the LyC escape fraction from low-mass galaxies at z = 1.3 - 3.0. We obtained rest-frame UV continuum imaging with the ACS/SBC and the WFC3/UVIS from the Hubble Space Telescope for eight strongly-lensed galaxies that were identified in the Sloan Giant Arc Survey (SGAS) and the Cluster Lensing And Supernova survey with Hubble (CLASH). The targeted galaxies were selected to be spectroscopically confirmed, highly magnified, and blue in their UV spectral shapes ($\beta<-1.7$). Our targets include intrinsically low luminosity galaxies down to a magnification-corrected absolute UV magnitude of $M_{\rm UV}\sim-14$. We perform custom-defined aperture photometry to place the most reliable upper limits of LyC escape from our sample. From our observations, we report no significant ($>$$2\sigma$) detections of LyC fluxes, placing 1$\sigma$ upper limits on the absolute LyC escape fractions of 3 - 15%. Our observations do not support the expected increased escape fractions of LyC photons from intrinsically UV faint sources. Considering the highly anisotropic geometry of LyC escape, increasing the sample size of faint galaxies in future LyC observations is crucial.

We investigate the formation of an ideal magnetized jet that originates from a disk acting as a boundary by conducting axisymmetric MHD simulations. Our simulations demonstrate that the magnetized jet is consistently launched and reaches a stable state. We extended the model setup to three dimensions to further advance our study. We performed 3D MHD simulations of the jet launched from a disk surface, achieving a stable and appropriate model setup. Additionally, we expanded our study by incorporating the companion star and examining the influence of the Roche potential on the jet material. Specifically, we investigate whether including the companion star in the model significantly affects the dynamical evolution of the jet. Our findings reveal the formation of an ``arc-like'' structure in the density map of the jet cross-section, which is attributed to the direct tidal effects. This implies that while the primary physical effects and characteristics of the outflow on a larger scale are attributed to the host accretion disk, the direct tidal effects on the jet dynamics have a substantial impact, particularly in the vicinity of the Roche lobe and towards the secondary star.

The structure and dynamics of the central bar of the Milky Way are still under debate whilst being fundamental ingredients for the evolution of our Galaxy. The recent Gaia DR3 offers an unprecedented detailed view of the 6D phase-space of the MW. We aim to characterise the dynamical moving groups across the MW disc, and use their large-scale distribution to help constrain the properties of the Galactic bar. We used wavelet transforms of the azimuthal velocity ($V_\phi$) distribution in bins of radial velocity to robustly detect the kinematic substructure in the Gaia DR3 catalogue. We then connected these structures across the disc to measure the azimuthal ($\phi$) and radial ($R$) gradients of the moving groups. We simulated thousands of perturbed distribution functions using Backwards Integration of feasible Galaxy models that include a bar, to compare them with the data and to explore and quantify the degeneracies. The radial gradient of the Hercules moving group ($\partial V_\phi/\partial R$ = 28.1$\pm$2.8 km$\,$s$^{-1}\,$kpc$^{-1}$) cannot be reproduced by our simple models of the Galaxy which show much larger slopes both for a fast and a slow bar. This suggests the need for more complex dynamics (e.g. spiral arms, a slowing bar, external perturbations, etc.). We measure an azimuthal gradient for Hercules of $\partial V_\phi/\partial \phi$ = -0.63$\pm$0.13$\,$km$\,$s$^{-1}$deg$^{-1}$ and find that it is compatible with both the slow and fast bar models. Our analysis points out that using this type of analysis at least two moving groups are needed to start breaking the degeneracies. We conclude that it is not sufficient for a model to replicate the local velocity distribution; it must also capture its larger-scale variations. The accurate quantification of the gradients, especially in the azimuthal direction, will be key for the understanding of the dynamics governing the disc. (ABR)

Measurements of the microlensing optical depth and event rate toward the Large Magellanic Cloud (LMC) can be used to probe the distribution and mass function of compact objects in the direction toward that galaxy - in the Milky Way disk, Milky Way dark matter halo, and the LMC itself. The previous measurements, based on small statistical samples of events, found that the optical depth is an order of magnitude smaller than that expected from the entire dark matter halo in the form of compact objects. However, these previous studies were not sensitive to long-duration events with Einstein timescales longer than 2.5-3 years, which are expected from massive ($10-100\,M_{\odot}$) and intermediate-mass ($10^2-10^5\,M_{\odot}$) black holes. Such events would have been missed by the previous studies and would not have been taken into account in calculations of the optical depth. Here, we present the analysis of nearly 20-year-long photometric monitoring of 78.7 million stars in the LMC by the Optical Gravitational Lensing Experiment (OGLE) from 2001 through 2020. We describe the observing setup, the construction of the 20-year OGLE dataset, the methods used for searching for microlensing events in the light curve data, and the calculation of the event detection efficiency. In total, we find 16 microlensing events (thirteen using an automated pipeline and three with manual searches), all of which have timescales shorter than 1 yr. We use a sample of thirteen events to measure the microlensing optical depth toward the LMC $\tau=(0.121 \pm 0.037)\times 10^{-7}$ and the event rate $\Gamma=(0.74 \pm 0.25)\times 10^{-7}\,\mathrm{yr}^{-1}\,\mathrm{star}^{-1}$. These numbers are consistent with lensing by stars in the Milky Way disk and the LMC itself, and demonstrate that massive and intermediate-mass black holes cannot comprise a significant fraction of dark matter.

One of the main challenges in galaxy formation that has emerged recently is the early assembly of massive galaxies. The observed number density and the maximum stellar mass ($M_{\star}$) of massive galaxies in the early Universe appear to be higher than model predictions, which may pose a serious problem to the LCDM cosmology. A major limitation in many previous studies is the large uncertainty in estimating $M_{\star}$ due to the lack of constraints in the rest-frame near-infrared part of the spectral energy distribution, which is critical to determining $M_{\star}$ accurately. Here we use data from a large JWST/MIRI survey in the PRIMER program to carry out a systematic analysis of massive galaxies at $z \sim 3-8$, leveraging photometric constraints at rest-frame $\gtrsim 1 \mu$m. We find a significant reduction in the number and mass densities of massive galaxies at $z > 5$ compared to earlier results that did not use the MIRI photometry. Within the standard $\Lambda$CDM cosmology, our results require a moderate increase in the baryon-to-star conversion efficiency ($\epsilon$) towards higher redshifts and higher $M_{\star}$. For the most massive galaxies at $z\sim 8$, the required $\epsilon$ is $\sim 0.3$, in comparison to $\epsilon \sim 0.14$ for typical low-redshift galaxies. Our findings are consistent with models assuming suppressed stellar feedback due to the high gas density and the associated short free-fall time expected for massive halos at high redshift.

With the expected large number of binary neutron star (BNS) observations through gravitational waves (GWs), third-generation GW detectors, Cosmic Explorer (CE) and Einstein Telescope (ET), will be able to constrain the tidal deformability, and hence the equation of state (EoS) of neutron star (NS) with exquisite precision. A subset of the detected BNS systems can retain residual eccentricity in the detector frequency band. We study the systematic errors due to unmodeled eccentricity in the tidal deformability measurement and its implications for NS EoS and redshift measurement via the Love siren method. We find that the systematic errors in the tidal deformability parameter exceed the statistical errors at an eccentricity of $\sim 10^{-3}$ ($\sim 3\times 10^{-4}$) at $10$Hz reference GW frequency for CE (ET). We show that these biases on tidal deformability parameter can significantly bias the NS EoS inference. Furthermore, the error on tidal deformability propagates to the source frame NS mass, which in turn biases the redshift inference. For CE, the redshift inference is significantly biased at an eccentricity of $\sim 10^{-3}$ (at a reference frequency of $10$Hz). We also study the implications of biased tidal deformability in testing the Kerr nature of black holes. Systematic error on the tidal deformability parameter leads to a non-zero value of tidal deformability for binary black holes, indicating a false deviation from the Kerr nature. Finally, we show that including eccentricity in the waveform model increases the statistical errors in tidal deformability measurement by a factor of $\lesssim 2$. Our study, therefore, highlights the importance of using accurate eccentric waveform models for GW parameter inference.

The TESS mission has provided the community with high-precision times series photometry for $\sim$2.8 million stars across the entire sky via the Full Frame Image (FFI) light curves produced by the TESS Science Processing Operations Centre (SPOC). This set of light curves is an extremely valuable resource for the discovery of transiting exoplanets and other stellar science. However, due to the sample selection, this set of light curves does not constitute a magnitude limited sample. In order to understand the effects of this sample selection, we use Gaia DR2 and DR3 to study the properties of the stars in the TESS-SPOC FFI light curve set, with the aim of providing vital context for further research using the sample. We report on the properties of the TESS-SPOC FFI Targets in Sectors 1 - 55 (covering Cycles 1 - 4). We cross-match the TESS-SPOC FFI Targets with the Gaia DR2 and DR3 catalogues of all targets brighter than Gaia magnitude 14 to understand the effects of sample selection on the overall stellar properties. This includes Gaia magnitude, parallax, radius, temperature, non-single star flags, luminosity, radial velocity and stellar surface gravity. In total, there are $\sim$16.7 million Gaia targets brighter than G=14, which when cross-matched with the TESS-SPOC FFI Targets leaves $\sim$2.75 million. We investigate the binarity of each TESS-SPOC FFI Target and calculate the radius detection limit from two detected TESS transits which could be detected around each target. Finally, we create a comprehensive main sequence TESS-SPOC FFI Target sample which can be utilised in future studies.

Orbital evolution is a critical process that sculpts planetary systems, particularly during their early stages where planet-disk interactions are expected to lead to the formation of resonant chains. Despite the theoretically expected prominence of such configurations, they are scarcely observed among long-period giant exoplanets. This disparity suggests an evolutionary sequence wherein giant planet systems originate in compact multi-resonant configurations, but subsequently become unstable, eventually relaxing to wider orbits--a phenomenon mirrored in our own solar system's early history. In this work, we present a suite of N-body simulations that model the instability-driven evolution of giant planet systems, originating from resonant initial conditions, through phases of disk-dispersal and beyond. By comparing the period ratio and normalized angular momentum deficit distributions of our synthetic aggregate of systems with the observational census of long-period Jovian planets, we derive constraints on the expected rate of orbital migration, efficiency of gas-driven eccentricity damping, and typical initial multiplicity. Our findings reveal a distinct inclination towards densely-packed initial conditions, weak damping, and high giant planet multiplicities. Furthermore, our models indicate that resonant chain origins do not facilitate the formation of Hot Jupiters via the coplanar high-eccentricity pathway at rates high enough to explain their observed prevalence.

The goal of this study is to conduct a timely analysis of the high-redshift star-forming galaxy populations, which will be informative in designing next-generation experiments and their extragalactic targets. We use the hydrodynamical simulation MillenniumTNG (MTNG) to model Lyman-alpha Emitting (LAE) galaxies to extract key properties such as their clustering and occupation statistics. We define LAEs through an empirical relation between star formation rate (SFR) and Lyman-alpha flux. We also explore two other definitions, finding that imposing an additional cut on the maximum stellar mass of the galaxy sample, which approximates the effect of a low escape fraction at high halo mass, leads to a 5-10\% decrease of the linear bias of the population. As expected, we find that the HOD mass parameters rapidly decrease with increasing number density. Additionally, the HOD parameter $\sigma$ also decreases with number density, implying that the SFR-halo mass relationship becomes tighter for low-luminosity objects. Surprisingly, the non-linear clustering, estimated by the parameter $r_0$, is fixed at fixed number density, whereas the linear bias parameter varies with redshift as $b(z) \propto (1 + z)$, suggesting that our LAE samples are relatively stable and long-lived. Finally, we study the amount of galaxy assembly bias present at $z = 2, \ 3$ and find that while at $z = 2$ it is roughly $\lesssim$10\%, at $z = 3$ it decreases significantly to $\lesssim$5\%. This suggests that assembly bias effects become less important at high $z$ likely due to the lower number of cumulative two-halo interactions (mergers, splashback, stripping, etc.). While our study is based on a single full-physics simulation, we expect our results to reflect the properties of LAEs in the Universe. We demonstrate that our findings are in good agreement with previous results using both observations and simulations.

We present the results from an analysis of multi-wavelength archival data on the multi-phase outflow in the starburst galaxy NGC 1808. We report the detection at 70 and 100 um of dust filaments that extend up to ~ 13 kpc from the galactic mid-plane and trace an edge-brightened biconical structure along the minor axis of the galaxy. The inner filaments are roughly co-spatial with previously identified optical dust filaments, extraplanar polycyclic aromatic hydrocarbon emission, and neutral and ionized gaseous outflows. The 70/160 um flux ratio, a proxy for dust temperature, is elevated along the edges of the cones, indicating that the dusty medium has been driven out of the central regions of these cones and possibly shock-heated by an outflow. We establish lower limits on the extraplanar dust mass and mean height above the stellar disk of log(M_d/M_sun) = 6.48 and |z| ~ 5 kpc, respectively. The energy requirement of (5.1-9.6) x 10^{56} ergs needed to lift the dusty material, assuming Milky-Way like dust-to-gas ratio, can be supplied by the current starburst, with measured star formation rate of 3.5-5.4 M_sun yr^{-1}, over a timescale of (4-26) xi^{-1} Myr, where xi is the efficiency of energy transfer. We conclude that a starburst-driven outflow is the most likely mechanism by which the dust features were formed.

Recent isolated galactic simulations show that the morphology of galactic discs in modified gravity differs from that of the standard dark matter model. In this study, we focused on the vertical structure of galactic discs and compared the bending instability in the vertical direction for both paradigms. To achieve this, we utilized high-resolution N-body simulations to construct two models in a specific nonlocal gravity theory (NLG) and the standard dark matter model and compared their stability against the bending perturbations. Our numerical results demonstrate that the outer regions of the disc are more susceptible to the instability in NLG, whereas the disc embedded in the dark matter halo is more unstable in the central regions. We then interpret these results based on the dispersion relation of the bending waves. To do so, we presented an analytical study to derive the dispersion relation in NLG. Our numerical results align with the predictions of our analytical models. Consequently, we conclude that the analysis of bending instability in galactic discs offers an explanation for the distinct vertical structures observed in simulated galactic discs under these two theories. These findings represent a significant step towards distinguishing between the modified gravity and dark matter models.

Modern simulation-based inference techniques use neural networks to solve inverse problems efficiently. One notable strategy is neural posterior estimation (NPE), wherein a neural network parameterizes a distribution to approximate the posterior. This approach is particularly advantageous for tackling low-latency or high-volume inverse problems. However, the accuracy of NPE varies significantly within the learned parameter space. This variability is observed even in seemingly straightforward systems like coupled-harmonic oscillators. This paper emphasizes the critical role of prior selection in ensuring the consistency of NPE outcomes. Our findings indicate a clear relationship between NPE performance across the parameter space and the number of similar samples trained on by the model. Thus, the prior should match the sample diversity across the parameter space to promote strong, uniform performance. Furthermore, we introduce a novel procedure, in which amortized and sequential NPE are combined to swiftly refine NPE predictions for individual events. This method substantially improves sample efficiency, on average from nearly 0% to 10-80% within ten minutes. Notably, our research demonstrates its real-world applicability by achieving a significant milestone: accurate and swift inference of posterior distributions for low-mass binary black hole (BBH) events with NPE.

While intensively studied, it remains unclear how the star formation (SF) in Infrared Dark Clouds (IRDCs) compares to that of nearby clouds. We study G351.77-0.53 (henceforth G351), a cluster-forming filamentary IRDC. We begin by characterizing its young stellar object (YSO) content. Based on the average parallax of likely members, we obtain a Gaia distance of $\sim\,2.0\pm0.14$ kpc, resolving the literature distance ambiguity. Using our Herschel-derived N(H$_2$) map, we measure a total gas mass of 10200 M$_{\odot}$ (within 11 pc$^2$) and the average line-mass profile of the entire filament, which we model as $\lambda =~1660 (w/\rm pc )^{0.62}\,\,M_{\odot}\,\rm{pc}^{-1}$. At $w < 0.63$ pc, our $\lambda$ profile is higher and has a steeper power-law index than $\lambda$ profiles extracted in Orion A and most of its substructures. Based on the YSOs inside the filament area, we estimate the SF efficiency (SFE) and SF rate (SFR). We calculate a factor of 5 incompleteness correction for our YSO catalog relative to Spitzer surveys of Orion A. The G351 SFE is $\sim 1.8$ times lower than that of Orion A and lower than the median value for local clouds. We measure SFR and gas masses to estimate the efficiency per free-fall time, $\epsilon _{\rm ff}$. We find that $\epsilon_{\rm ff}$ is $\sim$ 1.1 dex below the previously proposed mean local relation, and $\sim\,4.7\times$ below Orion A. These observations indicate that local SF-relations do not capture variations present in the Galaxy. We speculate that cloud youth and/or magnetic fields might account for the G351 inefficiency.

We develop the impulsiveness index, a new classification system for solar flares using the SDO/EVE 304 {\AA} Sun-as-a-star light curves. Impulsiveness classifies events based on the duration and intensity of the initial high-energy deposition of energy into the chromosphere. In stellar flare U-band light curves, Kowalski et al. (2013) found that impulsiveness is related to quantities such as a proxy for the Balmer jump ratio. However, the lack of direct spatial resolution in stellar flares limits our ability to explain this phenomenon. We calculate impulsiveness for 1368 solar flares between 04/2010 and 05/2014. We divide events into categories of low, mid, and high impulsiveness. We find, in a sample of 480 flares, that events with high maximum reconnection rate tend to also have high impulsiveness. For six case studies, we compare impulsiveness to magnetic shear, ribbon evolution, and energy release. We find that the end of the 304 {\AA} light curve rise phase in these case studies corresponds to the cessation of PIL-parallel ribbon motion, while PIL-perpendicular motion persists afterward in most cases. The measured guide field ratio for low and mid-impulsiveness case study flares decreases about an order of magnitude during the impulsive flare phase. Finally, we find that, in four of the six case studies, flares with higher, more persistent shear tend to have low impulsiveness. Our study suggests that impulsiveness may be related to other properties of the impulsive phase, though more work is needed to verify this relationship and apply our findings to stellar flare physics.

Recent observations of reflected propagating and standing slow-mode waves in hot flaring coronal loops have spurred our investigation into their underlying excitation and damping mechanisms. To understand these processes, we conduct 2.5D magnetohydrodynamic (MHD) simulations using an arcade active region model that includes a hot and dense loop. Our simulations allow for in-depth parametric investigations complementing and expanding our previous 3D MHD modeling results. We excite these waves in two distinct models as motivated by observations from the SDO/AIA. Model 1 incorporates classical compressive viscosity coefficient, while Model 2 adopts a 10-times enhanced viscosity coefficient. We find that: (1) Our 2.5D MHD simulations reinforce previous conclusions derived from 1D and 3D MHD models that significantly enhanced viscosity is crucial for the rapid excitation of standing slow waves with damping times consistent with observations by Wang et al. (2015). (2) We uncover that nonlinearity in Model 1 delays the conversion of a reflected propagating wave into a standing wave. In contrast, Model 2 exhibits a much weak influence of nonlinearity. (3) Our results reveal that the transverse temperature structure holds more influence on wave behavior than the density structure. In Model 1, increased loop temperature contrast significantly enhances wave trapping within the structure, mitigating the impact of temperature-dependent viscous damping. Conversely, in Model 2, the impact of temperature structure on wave behavior weakens in comparison to the effect of viscosity. (4) Model 1 displays evident nonlinear coupling to the fast and kink magnetoacoustic waves and pronounced wave leakage into the corona. However, analyzing three observed wave events by SDO/AIA aligns with Model 2 predictions, providing further support for the substantial viscosity increase.

A fairly uniform cosmic-ray (CR) distribution is observed near the Sun, except in the nearby Eridu cloud, which shows an unexplained 30-50% deficit in GeV to TeV CR flux. To explore the origin of this deficit, we studied the Reticulum cloud, which shares notable traits with Eridu: a comparable distance in the low-density region of the Local Valley and a filamentary structure of atomic hydrogen extending along ordered magnetic-field lines that are steeply inclined to the Galactic plane. Using 14 years of Fermi-LAT data in the 0.16 to 63 GeV energy band, we found that the gamma-ray emissivity in the Reticulum cloud is fully consistent with the average spectrum measured in the solar neighbourhood, but this emissivity, and therefore the CR flux, is 1.57 $\pm$ 0.09 times larger than in Eridu across the whole energy band. The difference cannot be attributed to uncertainties in gas mass. Nevertheless, we find that the two clouds are similar in many respects at a parsec scale: both have magnetic-field strengths of a few micro-Gauss in the plane of the sky; both are in approximate equilibrium between magnetic and thermal pressures; they have similar turbulent velocities and sonic Mach numbers; and both show magnetic-field regularity with a dispersion in orientation lower than 10-15 degrees over large zones. The gas in Reticulum is colder and denser than in Eridu, but we find similar parallel diffusion coefficients around a few times 1e28 cm2/s in both clouds if CRs above 1 GV in rigidity diffuse on resonant, self-excited Alfv\'en waves that are damped by ion-neutral interactions. The loss of CRs in Eridu remains unexplained, but these two clouds provide important test cases to further study how magnetic turbulence, line tangling, and ion-neutral damping regulate CR diffusion in the dominant gas phase of the interstellar medium.

The IceCube Neutrino Observatory relies on an array of photomultiplier tubes to detect Cherenkov light produced by charged particles in the South Pole ice. IceCube data analyses depend on an in-depth characterization of the glacial ice, and on novel approaches in event reconstruction that utilize fast approximations of photoelectron yields. Here, a more accurate model is derived for event reconstruction that better captures our current knowledge of ice optical properties. When evaluated on a Monte Carlo simulation set, the median angular resolution for in-ice particle showers improves by over a factor of three compared to a reconstruction based on a simplified model of the ice. The most substantial improvement is obtained when including effects of birefringence due to the polycrystalline structure of the ice. When evaluated on data classified as particle showers in the high-energy starting events sample, a significantly improved description of the events is observed.

The TESS mission has provided a wealth of asteroseismic data for solar-like oscillators. However, these data are subject to varying cadences, large gaps, and unequal sampling, which complicates analysis in the frequency domain. One solution is to model the oscillations in the time domain by treating them as stochastically damped simple harmonic oscillators through a linear combination of Gaussian Process kernels. We demonstrate this method on the well-studied subgiant star nu Indi and a sample of Kepler red giant stars observed by TESS, finding that the time domain model achieves an almost two-fold increase in accuracy for measuring {\nu}max compared to typical frequency domain methods. To apply the method to new detections, we use stellar parameters from Gaia DR3 and the TESS input catalog to calculate revised asteroseismic detection probabilities for all TESS input catalog targets with T<12 mag and a predicted {\nu}max>240{\mu}Hz. We also provide a software tool to calculate detection probabilities for any target of interest. Using the updated detection probabilities we show that time-domain asteroseismology is sensitive enough to recover marginal detections, which may explain the current small number of frequency-based detections of TESS oscillations compared to pre-flight expectations.

A new type of interferometer, called High Order Harmonic Interferometer (HOHI), was proposed by Wu (1996) for imaging by aperture synthesis radio telescope. Its feasibility was proven by theoretical analysis. Before putting HOHI in practical use, computer simulation is a necessary intermediate stage. In this paper the theoretical analysis is reviewed. Then, computer simulation, including its algorithm, calculation and generated maps, is presented. The theoretical analysis is validated by studying these maps.

We report on a measurement of astrophysical tau neutrinos with 9.7 years of IceCube data. Using convolutional neural networks trained on images derived from simulated events, seven candidate $\nu_\tau$ events were found with visible energies ranging from roughly 20 TeV to 1 PeV and a median expected parent $\nu_\tau$ energy of about 200 TeV. Considering backgrounds from astrophysical and atmospheric neutrinos, and muons from $\pi^\pm/K^\pm$ decays in atmospheric air showers, we obtain a total estimated background of about 0.5 events, dominated by non-$\nu_\tau$ astrophysical neutrinos. Thus, we rule out the absence of astrophysical $\nu_\tau$ at the $5\sigma$ level. The measured astrophysical $\nu_\tau$ flux is consistent with expectations based on previously published IceCube astrophysical neutrino flux measurements and neutrino oscillations.

Prediction of the Solar Energetic Particle (SEP) events garner increasing interest as space missions extend beyond Earth's protective magnetosphere. These events, which are, in most cases, products of magnetic reconnection-driven processes during solar flares or fast coronal-mass-ejection-driven shock waves, pose significant radiation hazards to aviation, space-based electronics, and particularly, space exploration. In this work, we utilize the recently developed dataset that combines the Solar Dynamics Observatory/Helioseismic and Magnetic Imager's (SDO/HMI) Space weather HMI Active Region Patches (SHARP) and the Solar and Heliospheric Observatory/Michelson Doppler Imager's (SoHO/MDI) Space Weather MDI Active Region Patches (SMARP). We employ a suite of machine learning strategies, including Support Vector Machines (SVM) and regression models, to evaluate the predictive potential of this new data product for a forecast of post-solar flare SEP events. Our study indicates that despite the augmented volume of data, the prediction accuracy reaches 0.7 +- 0.1, which aligns with but does not exceed these published benchmarks. A linear SVM model with training and testing configurations that mimic an operational setting (positive-negative imbalance) reveals a slight increase (+ 0.04 +- 0.05) in the accuracy of a 14-hour SEP forecast compared to previous studies. This outcome emphasizes the imperative for more sophisticated, physics-informed models to better understand the underlying processes leading to SEP events.

This work investigates observational properties, namely the shadow and photon ring structure, of emission profiles originated near compact objects. In particular, we consider a distorted and deformed compact object characterized by quadrupoles and surrounded by an optically thin and geometrically thin accretion disk with different emission profiles modeled by the Johnson's Standard-Unbound (SU) distribution in the reference frame of the emitter. Under these assumptions, we produce the observed intensity profiles and shadow images for a face-on observer. Our results indicate that, due to the fact that modifications of the quadrupole parameters affect the radius of the innermost stable circular orbit (ISCO) and the photon sphere (PS), the observed shadow images and their properties are significantly influenced by the quadrupole parameters and emission profiles. Furthermore, we analyze the impact of the presence of a dark matter halo in the observational imprints considered and verify that both the increase in the matter contained in the halo or decrease in the length-scale of the halo lead to an increase in the size of the observed shadow. Our results indicate potential degeneracies between the observational features of distorded and deformed compact objects with those of spherically symmetric blackholes, which could be assessed by a comparison with the current and future generation of optical experiments in gravitational physics.

Fast radio bursts (FRBs) are luminous millisecond-duration radio pulses with extragalactic origin, which were discovered more than a decade ago. Despite the numerous samples, the physical origin of FRBs remains poorly understood. FRBs have been thought to originate from young magnetars or accreting compact objects (COs). Massive stars or COs are predicted to be embedded in the accretion disks of active galactic nuclei (AGNs). The dense disk absorbs FRBs severely, making them difficult to observe. However, progenitors ejecta or outflow feedback from the accreting COs interact with the disk material to form a cavity. The existence of the cavity can reduce the absorption by the dense disk materials, making FRBs escape. Here we investigate the production and propagation of FRBs in AGN disks and find that the AGN environments lead to the following unique observational properties, which can be verified in future observation. First, the dense material in the disk can cause large dispersion measure (DM) and rotation measure (RM). Second, the toroidal magnetic field in the AGN disk can cause Faraday conversion. Third, during the shock breakout, DM and RM show non-power-law evolution patterns over time. Fourth, for accreting-powered models, higher accretion rates lead to more bright bursts in AGN disks.

The Jeans criterion sets the foundation of our understanding of gravitational collapse. Jog studied the fragmentation of gas under external tides and derived a dispersion relation $$ l' = l_{\rm Jeans} \frac{1} {(1 + \lambda_0' / 4 \pi G \rho_0)^{1/2}} \;. $$ She further concludes that the Jeans mass is $m_{\rm incorrect}'=m_{\rm Jeans} ( 1/(1 + \lambda_0' / 4 \pi G \rho_0)^{3/2})$. We clarify that due to the inhomogeneous nature of tides, this characteristic mass is incorrect. Under weak tides, the mass is $m \approx \rho\, l_1 l_2 l_3$, where the modifications to Jeans lengths along all three dimensions need to be considered; when the tide is strong enough, collapse can only occur once 1 or 2 dimensions. In the latter case, tides can stretch the gas, leading to the formation of filaments.

We presented the multi-filter light curves of CSS_J154915.7+375506 inaugurally, which were observed by the 1.5 m AZT-22 telescope at Maidanak Astronomical Observatory. A low-resolution spectrum obtained by LAMOST reveals it is an A-type close binary. By analyzing the BVRI total-eclipse light curves, we are able to derive a reliable photometric solution for this system, which indicates that CSS_J154915.7+375506 is an extremely low-mass-ratio (q=0.138) marginal contact binary system. The location in the HR diagram shows that its secondary component with a much smaller mass is the more evolved one, indicating the mass ratio reversal occurred. The present secondary component had transferred a significant amount of mass to the present primary one. By the combination of a total of 20 times of minimum, we investigated its O-C curve. A periodic oscillation and a possible period decrease have been detected. As the period decreases, the system will evolve towards the contact phase. This makes CSS\_J154915.7+375506 a valuable case to study the formation scenario of contact binaries through mass reversal. The periodic oscillation suggested a third body with a minimal mass of $0.91\,M_{\odot}$, which is larger than that of the less massive component in the central binary. This implies that the secondary body was not replaced by the third body during early stellar interactions, indicating that it is a fossil system and retains its original dynamical information.

We present the timing solution for the 5.31-ms spider millisecond pulsar (MSP) J1242-4712, discovered with the GMRT. PSR J1242-4712 orbits a companion of minimum mass 0.08 M$_{\odot}$ with an orbital period of 7.7 hrs and occupies a relatively unexplored region in the orbital period versus companion mass space. We did not detect gamma-ray pulsations for this MSP, and also could not identify the optical counterpart for PSR J1242-4712 in available optical/near-infrared data. The profile of J1242-4712 evolves with frequency showing a clear single component at lower frequencies and a three-component profile at 650 MHz. PSR J1242-4712 eclipses for a very short duration near superior conjunction (orbital phase ~ 0.23-0.25) below 360 MHz. Moreover, significant DM delays and errors in pulse times of arrivals are observed near inferior conjunction (orbital phase ~ 0.7), along with an observed eclipse in one epoch at 650 MHz. Observed eclipses and significant orbital period variability suggest that PSR J1242-4712 is possibly not a He-WD binary, but has a semi or non-degenerate companion, indicating that this is a ``spider" MSP lying in a region between typical black widows and redbacks. This system may represent a distinct category of spider MSPs, displaying characteristics that bridge the gap between known black widow and redback MSPs.

In this study, we investigate interstellar absorption lines along the line of sight toward the galactic low-mass X-ray binary Cygnus X-2. We combine absorption line data obtained from high-resolution X-ray spectra collected with Chandra and XMM-Newton satellites, along with Far-UV absorption lines observed by the Hubble Space Telescope's (HST) Cosmic Origins Spectrograph (COS) Instrument. Our primary objective is to understand the abundance and depletion of oxygen, iron, sulfur, and carbon. To achieve this, we have developed an analysis pipeline that simultaneously fits both the UV and X-ray datasets. This novel approach takes into account the line spread function (LSF) of HST/COS, enhancing the precision of our results. We examine the absorption lines of FeII, SII, CII, and CI present in the FUV spectrum of Cygnus X-2, revealing the presence of at least two distinct absorbers characterized by different velocities. Additionally, we employ Cloudy simulations to compare our findings concerning the ionic ratios for the studied elements. We find that gaseous iron and sulfur exist in their singly ionized forms, Fe II and S II, respectively, while the abundances of CII and CI do not agree with the Cloudy simulations of the neutral ISM. Finally, we explore discrepancies in the X-ray atomic data of iron and discuss their impact on the overall abundance and depletion of iron.

The project aims to use machine learning algorithms to fit the free parameters of an isotopic scaling model to elemental observations. The processes considered are massive star nucleosynthesis, Type Ia SNe, the s-process, the r-process, and p-isotope production. The analysis on the successful fits seeks to minimize the reduced chi squared between the model and the data. Based upon the successful refinement of the isotopic parameterized scaling model, a table providing the 287 stable isotopic abundances as a function of metallicity, separated into astrophysical processes, is useful for identifying the chemical history of them. The table provides a complete averaged chemical history for the Galaxy, subject to the underlying model constraints.

The mass assembly in star forming regions arises from the hierarchical structure in molecular clouds in tandem with fragmentation at different scales. In this paper, we present a study of the fragmentation of massive clumps covering a range of evolutionary states, selected from the ATLASGAL survey, using the compact configuration of the Submillimeter Array. The observations reveal a wide diversity in the fragmentation properties with about 60% of the sources showing limited to no fragmentation at the 2" scale, or a physical scale of 0.015 - 0.09 pc. We also find several examples where the cores detected with the Submillimeter array are significantly offset from the clump potential suggesting that initial fragmentation does not result in the formation of a large number of Jeans mass fragments. The fraction of the clump mass that is in compact structures is seen to increase with source evolution. We also see a significant correlation between the maximum mass of a fragment and the bolometric luminosity of the parent clump. These suggest that massive star formation proceeds through clump fed core accretion with the initial fragmentation being dependent on the density structure of the clumps and/or magnetic fields.

One of the surprising aspects of the present Universe, is the absence of any noticeable observable effects of higher-rank anti-symmetric tensor fields, such as space-time torsion, in any natural phenomena. Here we address the possible explanation of torsion, which may often be identified with the field strength tensor of the second rank antisymmetric Kalb-Ramond field. Within the framework of f(R) gravity, we explore the cosmological evolution of the scalar degrees of freedom associated with higher curvature term in a general higher curvature model $f (R) = R +\alpha_n R^n$. We show that while the values of different cosmological parameters follow acceptable values in the framework of standard cosmology at different epochs for different forms of higher curvature gravity (i.e. different values of n ), only for Starobinsky model (n = 2), the Kalb Ramond field gets naturally suppressed with cosmological evolution. In contrast, for other models (n both positive and negative), despite their agreement with standard cosmology, the scalar field associated with the higher derivative degree of freedom induces an enhancement in Kalb-Ramond field and thereby contradicts the observation. The result does note change even if we include the Cosmological Constant. Thus our result reveals that among different $f(R)$ models, Starobinsky model successfully explains the suppression of space-time torsion along with a consistent cosmological evolution.

Recent Monte Carlo plasma simulations to study in crystallizing carbon-oxygen (CO) white dwarfs (WDs) the phase separation of Ne22 (the most abundant metal after carbon and oxygen) have shown that, under the right conditions, a distillation process that transports Ne22 toward the WD centre is efficient and releases a considerable amount of gravitational energy that can lead to cooling delays of up to several Gyr. Here we present the first CO WD stellar evolution models that self-consistently include the effect of neon distillation, and cover the full range of CO WD masses, for a progenitor metallicity twice-solar appropriate for the old open cluster NGC 6791. The old age (about 8.5 Gyr) and high metallicity of this cluster -- hence the high neon content (about 3% by mass) in the cores of its WDs -- maximize the effect of neon distillation in the models to be compared with the observed cooling sequence. We discuss the effect of distillation on the internal chemical stratification and cooling time of the models, confirming that distillation causes cooling delays up to several Gyr, that depend in a non-monotonic way on the mass. We also show how our models produce luminosity functions (LFs) that can match the faint end of the observed WD LF in NGC 6791, for ages consistent with the range determined from a sample of cluster's eclipsing binary stars, and the main sequence turn-off. Without the inclusion of distillation the theoretical WD cooling sequences reach too faint magnitudes compared to the observations. We also propose James Webb Space Telescope observations that can independently demonstrate the efficiency of neon distillation in the interiors of NGC 6791 WDs, and help resolve the current uncertainty on the treatment of the electron conduction opacities for the hydrogen-helium envelope of the WD models.

Classical Cepheids were the first stellar standard candles and have played a crucial role for astronomical distance measurements ever since the discovery of the Leavitt law (period-luminosity relation). Enormous improvements in distance accuracy have been achieved since Hertzsprung's first application of Leavitt's law to measure the distance to the Small Magellanic Cloud in 1913, notably in very recent years thanks to a large data set of highly accurate space astrometry from the ESA mission Gaia. Complemented by homogeneous space photometry, Cepheids enable the most accurate distance estimates to galaxies hosting type-Ia supernovae up to approximately 70 Mpc distant. Here, I review the history of Cepheid distance measurements, open questions on the side of stellar astrophysics, and recent studies seeking to quantify and mitigate systematics with a view to further improve the accuracy on the Hubble constant. For example, the recently launched James Webb Space Telescope will enhance precision due to 4x lower sensitivity to source blending in crowded regions and greater sensitivity in dust-insensitive infrared bands. Future 30m-class telescopes could in principle further improve Cepheid distance measurements towards the Hubble flow, if technical challenges related to a continuously evolving instrument can be overcome.

The NASA Double Asteroid Redirection Test (DART) spacecraft successfully impacted the Didymos-Dimorphos binary asteroid system on 2022 September 26 UTC. We provide an update to its pre-impact mutual orbit and estimate the post-impact physical and orbital parameters, derived using ground-based photometric observations taken from July 2022 to February 2023. We found that the total change of the orbital period was $-33.240 \pm 0.072$ min. (all uncertainties are 3$\sigma$). We obtained the eccentricity of the post-impact orbit to be $0.028 \pm 0.016$ and the apsidal precession rate of $7.3 \pm 2.0$ deg./day from the impact to 2022 December 2. The data taken later in December to February suggest that the eccentricity dropped close to zero or the orbit became chaotic approximately 70 days after the impact. Most of the period change took place immediately after the impact but in a few weeks following the impact it was followed by additional change of $-27^{+19}_{-58}$ seconds or $-19 \pm 18$ seconds (the two values depend on the approach we used to describe the evolution of the orbital period after the impact -- an exponentially decreasing angular acceleration or an assumption of a constant orbital period, which changed abruptly some time after the impact, respectively). We estimate the pre-impact Dimorphos-Didymos size ratio was $0.223 \pm 0.012$ and the post-impact is $0.202 \pm 0.018$, which indicates a marginally significant reduction of Dimorphos' volume by ($9 \pm 9) \%$ as the result of the impact.

During the most active period of star formation in galaxies, which occurs in the redshift range 1<z<3, strong bursts of star formation result in significant quantities of dust, which obscures new stars being formed as their UV/optical light is absorbed and then re-emitted in the infrared, which redshifts into the mm/sub-mm bands for these early times. To get a complete picture of the high-z galaxy population, we need to survey a large patch of the sky in the sub-mm with sufficient angular resolution to resolve all galaxies, but we also need the depth to fully sample their cosmic evolution, and therefore obtain their redshifts using direct mm spectroscopy with a very wide frequency coverage. This requires a large single-dish sub-mm telescope with fast mapping speeds at high sensitivity and angular resolution, a large bandwidth with good spectral resolution and multiplex spectroscopic capabilities. The proposed 50-m Atacama Large Aperture Submillimeter Telescope (AtLAST) will deliver these specifications. We discuss how AtLAST allows us to study the whole population of high-z galaxies, including the dusty star-forming ones which can only be detected and studied in the sub-mm, and obtain a wealth of information for each of these up to z~7: gas content, cooling budget, star formation rate, dust mass, and dust temperature. We present worked examples of surveys that AtLAST can perform, both deep and wide, and also focused on galaxies in proto-clusters. In addition we show how such surveys with AtLAST can measure the growth rate and the Hubble constant with high accuracy, and demonstrate the power of the line-intensity mapping method in the mm/sub-mm wavebands to constrain the cosmic expansion history at high redshifts, as good examples of what can uniquely be done by AtLAST in this research field.

Multi-wavelength observations indicate that the intracluster medium in some galaxy clusters contains cold filaments, while their formation mechanism remains debated. Using hydrodynamic simulations, we show that cold filaments could naturally condense out of hot gaseous wake flows uplifted by the jet-inflated active galactic nucleus (AGN) bubbles. Consistent with observations, the simulated filaments extend to tens of kpc from the cluster center, with a representative mass of $\rm 10^{8}- 10^{9}\ M_{\odot}$ for a typical AGN outburst energy of $10^{60}~ \rm erg$. They show smooth velocity gradients, stretching typically from inner inflows to outer outflows with velocity dispersions of several hundred $\rm km\ s^{-1}$. The properties of cold filaments are affected substantially by jet properties. Compared to kinetic energy-dominated jets, thermal energy-dominated jets tend to produce longer cold filaments with higher masses. With the same jet energy, AGN jets with an earlier turn-on time, a lower jet base, or a higher power heat the cluster center more effectively, and produce shorter filaments at a much later epoch.

The stability of galaxies is either explained by the existence of dark matter or caused by a modification of Newtonian acceleration (MOND). Here we show that the modification of the Newtonian dynamics can equally well be obtained by a modification of Newton's law of universal gravitational attraction (MOGA), by which an inverse square attraction from a distant object is replaced with an inverse attraction. This modification is often proposed in the standard model, and with the modification of the attraction caused by dark matter. The recently derived algorithm, Eur. Phys. J. Plus 137, 99 (2022); Class. Quantum Grav. 39, 225006 (2022), for classical celestial dynamics is used to simulate models of the Milky Way in an expanding universe and with either MOND or MOGA. The simulations show that the galaxies with MOND dynamics are unstable whereas MOGA stabilizes the galaxies. The rotation velocities for objects in galaxies with classical Newtonian dynamics decline inversely proportional to the square root of the distance $r$ to the galaxy's center. However, the rotation velocities are relatively independent of $r$ for MOGA and qualitatively in agreement with experimentally determined rotation curves for galaxies in the Universe. The modification of the attractions may be caused by the masses of the objects in the central part of the galaxy by the lensing of gravitational waves from far-away objects in the galaxy.

We present a detailed analysis of the observations with the Hard X-ray Modulation Telescope of the black hole X-ray transient 4U~1543-47 during its outburst in 2021. We find a clear state transition during the outburst decay of the source. Using previous measurements of the black-hole mass and distance to the source, the source luminosity during this transition is close to the Eddington limit. The light curves before and after the transition can be fitted by two exponential functions with short ($\sim 16$ days) and long ($\sim 130$ days) decay time scales, respectively. We detect strong reflection features in all observations that can be described with either the RelxillNS or Reflionx_bb reflection models, both of which have a black-body incident spectrum. In the super-Eddington state, we observe a Comptonized component characterized by a low electron temperature of approximately 2.0 keV. We suggest that this component appears exclusively within the inner radiation-pressure dominated region of the supercritical disk as a part of the intrinsic spectrum of the accretion disk itself. This feature vanishes as the source transitions into the sub-Eddington state. The emissivity index of the accretion disk in the reflection component is significantly different before and after the transition, $\sim3.0$-$5.0$ and $\sim7.0$-$9.0$ in the super- and sub-Eddington states, respectively. Based on the reflection geometry of returning disk radiation, the geometrically thicker the accretion disk, the smaller the emissivity index. Therefore, we propose that the transition is primarily driven by the change of the accretion flow from a supercritical to a thin disk configuration.

See thesis for complete abstract. Primordial black holes (PBHs) can form in the early universe, and there are several mass windows in which their abundance today may be large enough to comprise a significant part of the dark matter density. Additionally, numerical relativity (NR) allows one to investigate the formation processes of PBHs in the fully nonlinear strong-gravity regime. In this thesis, we will describe the use of NR methods to study PBH formation, motivated in particular by open questions about the nonspherical effects PBH formation in a matter-dominated early universe. We demonstrate that superhorizon non-linear perturbations can collapse and form PBHs via the direct collapse or the accretion collapse mechanisms in a matter-dominated universe. The heaviest perturbations collapse via the direct collapse mechanism, while lighter perturbations trigger an accretion process that causes a rapid collapse of the ambient DM. From the hoop conjecture we propose an analytic criterion to determine whether a given perturbation will collapse via the direct or accretion mechanism and we compute the timescale of collapse. Independent of the formation mechanism, the PBH forms within an efold after collapse is initiated and with a small initial mass compared to the Hubble horizon, $M_\textrm{BH} H_0\sim 10^{-2}m_\mathrm{Pl}^2$. Finally, we find that PBH formation is followed by extremely rapid growth $M_\textrm{BH}\propto H^{-\beta}$ with $\beta\gg 1$, during which the PBH acquires most of its mass. Furthermore, we study the formation of spinning primordial black holes during an early matter-dominated era. Using non-linear 3+1D general relativistic simulations, we compute the efficiency of mass and angular momentum transfer in the process -- which we find to be $\mathcal{O}(10\%)$. Abstract continues in thesis.

The formation of solid macroscopic grains (pebbles) in protoplanetary discs is the first step toward planet formation. We aim to study the distribution of pebbles and the chemical composition of their ice mantles in a young protoplanetary disc. We use the two-dimensional hydrodynamical code FEOSAD in the thin-disc approximation, which is designed to model the global evolution of a self-gravitating viscous protoplanetary disc taking into account dust coagulation and fragmentation, thermal balance, and phase transitions and transport of the main volatiles (H$_2$O, CO$_{2}$, CH$_{4}$ and CO), which can reside in the gas, on small dust ($<1$ $\mu$m), on grown dust ($>1$ $\mu$m) and on pebbles. We model the dynamics of the protoplanetary disc from the cloud collapse to the 500 kyr moment. We determine the spatial distribution of pebbles and composition of their ice mantles and estimate the mass of volatiles on pebbles, grown dust and small dust. We show that pebbles form as early as 50 kyr after the disc formation and exist until the end of simulation (500 kyr), providing prerequisites for planet formation. All pebbles formed in the model are covered by icy mantles. Using a model considering accretion and desorption of volatiles onto dust/pebbles, we find that the ice mantles on pebbles consist mainly of H$_2$O and CO$_{2}$, and are carbon-depleted compared to gas and ices on small and grown dust, which contain more CO and CH$_4$. This suggests a possible dominance of oxygen in the composition of planets formed from pebbles under these conditions.

The infrared (IR) range is extremely useful in the context of chemical abundance studies of the gas-phase interstellar medium (ISM) due to the large variety of ionic species traced in this regime, the negligible effects from dust attenuation or temperature stratification, and the amount of data that has been and will be released in the coming years. Taking advantage of available IR emission lines, we analysed the chemical content of the gas-phase ISM in a sample of 131 Star-Forming Galaxies (SFGs) and 73 Active Galactic Nuclei (AGNs). Particularly, we derived the chemical content via their total oxygen abundance in combination with nitrogen and sulfur abundances, and with the ionisation parameter. We used a new version of the code HII-CHI-Mistry-IR v3.1 which allows us to estimate log(N/O), 12+log(O/H), log(U), and, for the first time, 12+log(S/H) from IR emission lines, which can be applied to both SFGs and AGNs. We tested that the estimations from this new version, that only considers sulfur lines for the derivation of sulfur abundances, are compatible with previous studies. While most of the SFGs and AGNs show solar log(N/O) abundances, we found a large spread in the log(S/O) relative abundances. Specifically, we found extremely low log(S/O) values (1/10th solar) in some SFGs and AGNs with solar-like oxygen abundances. This result warns against the use of optical and IR sulfur emission lines to estimate oxygen abundances when no prior estimation of log(S/O) is provided.

We discuss some of the the open questions and the roadmap in the physics of primordial black holes. Black holes are the only dark matter candidate that is known to actually exit. Their conjectured primordial role is admittedly based on hypothesis rather than fact, most straightforwardly as a simple extension to the standard models of inflation, or even, in homage to quantum physics, more controversially via a slowing-down of Hawking evaporation. Regardless of one's stance on the theoretical basis for their existence, the possibility of primordial black holes playing a novel role in dark matter physics and gravitational wave astronomy opens up a rich astrophysical phenomenology that we lay out in this brief overview.

Planets orbiting members of open or globular clusters offer a great opportunity to study exoplanet populations systematically as stars within clusters provide a mostly homogeneous sample at least in chemical composition and stellar age. However, even though there have been coordinated efforts to search for exoplanets in stellar clusters, only a small number of planets has been detected. One successful example is the seven-year radial velocity (RV) survey "Search for giant planets in M67" of 88 stars in the open cluster M67 which led to the discovery of five giant planets, including three close-in ($P < 10$ days) hot-Jupiters. In this work, we continue and extend the observation of stars in M67 with the aim to search for additional planets. We conducted spectroscopic observations with the HPF, HARPS, HARPS-North, and SOPHIE spectrographs of 11 stars in M67. Six of our targets showed a variation or long-term trends in their RV during the original survey, while the other five were not observed in the original sample bringing the total number of stars to 93. An analysis of the radial velocities revealed one additional planet around the turn-off point star S1429 and gave solutions for the orbits of stellar companions around S2207 and YBP2018. S1429 b is a warm Jupiter on a likely circular orbit with a period of $77.48_{-0.19}^{+0.18}$ days and a minimum mass $\text{M} \sin i = 1.80 \pm 0.2$ M$_\text{J}$. We update the hot-Jupiter occurrence rate in M67 to include the five new stars, deriving $4.2_{-2.3}^{+4.1} \%$ when considering all stars, and $5.4_{-3.0}^{+5.1} \%$ if binary star systems are removed.

SRON (Netherlands Institute for Space Research) is developing the Focal Plane Assembly (FPA) for Athena X-IFU, whose Demonstration Model (DM) will use for the first time a time domain multiplexing (TDM)-based readout system for the on-board transition-edge sensors (TES). We report on the characterization activities on a TDM setup provided by NASA Goddard Space Flight Center (GSFC) and National Institute for Standards and Technology (NIST) and tested in SRON cryogenic test facilities. The goal of these activities is to study the impact of the longer harness, closer to X-IFU specs, in a different EMI environment and switching from a single-ended to a differential readout scheme. In this contribution we describe the advancement in the debugging of the system in the SRON cryostat, which led to the demonstration of the nominal spectral performance of 2.8 eV at 5.9~keV with 16-row multiplexing, as well as an outlook for the future endeavours for the TDM readout integration on X-IFU's FPA-DM at SRON.

At SRON we have been developing X-ray TES micro-calorimeters as backup technology for the X-ray Integral Field Unit (X-IFU) of the Athena mission, demonstrating excellent resolving powers both under DC and AC bias. We also developed a frequency-domain multiplexing (FDM) readout technology, where each TES is coupled to a superconducting band-pass LC resonator and AC biased at MHz frequencies through a common readout line. The TES signals are summed at the input of a superconducting quantum interference device (SQUID), which performs a first amplification at cryogenic stage. Custom analog front-end electronics and digital boards take care of further amplifying the signals at room temperature and of the modulation/demodulation of the TES signals and bias carrier, respectively. We report on the most recent developments on our FDM technology, which involves a two-channel demonstration with a total of 70 pixels with a summed energy resolution of 2.34 +/- 0.02 eV at 5.9 keV without spectral performance degradation with respect to single-channel operation. Moreover, we discuss prospects towards the scaling-up to a larger multiplexing factor up to 78 pixels per channel in a 1-6 MHz readout bandwidth.

By the end of the next decade, we hope to have detected strongly lensed gravitational waves by galaxies or clusters. Although there exist optimal methods for identifying lensed signal, it is shown that machine learning (ML) algorithms can give comparable performance but are orders of magnitude faster than non-ML methods. We present the SLICK pipeline which comprises a parallel network based on deep learning. We analyse the Q-transform maps (QT maps) and the Sine-Gaussian maps (SGP-maps) generated for the binary black hole signals injected in Gaussian as well as real noise. We compare our network performance with the previous work and find that the efficiency of our model is higher by a factor of 5 at a false positive rate of 0.001. Further, we show that including SGP maps with QT maps data results in a better performance than analysing QT maps alone. When combined with sky localisation constraints, we hope to get unprecedented accuracy in the predictions than previously possible. We also evaluate our model on the real events detected by the LIGO--Virgo collaboration and find that our network correctly classifies all of them, consistent with non-detection of lensing.

We report new Very Large Array high-resolution observations of the radio jet from the outbursting high-mass star S255IR~NIRS3. The images at 6, 10, and 22.2 GHz confirm the existence of a new lobe emerging to the SW and expanding at a mean speed of ~285 km/s, about half as fast as the NE lobe. The new data allow us to reproduce both the morphology and the continuum spectrum of the two lobes with the model already adopted in our previous studies. We conclude that in all likelihood both lobes are powered by the same accretion outburst. We also find that the jet is currently fading down, recollimating, and recombining.

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for $U(1)_{B-L}$ gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the $U(1)_{B-L}$ gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM.

Observations by the Voyager and Cassini spacecrafts have revealed various striking features of the gap structure in Saturn's ring, such as the density waves, sharp edge, and vertical wall structure. In order to explain these features in a single simulation, we perform a high-resolution (N~10^6-10^7) global full N-body simulation of gap formation by an embedded satellite considering gravitational interactions and inelastic collisions among all ring particles and the satellite, while these features have been mostly investigated separately with different theoretical approaches: the streamline models, 1D diffusion models, and local N-body simulation. As a first attempt of a series of papers, we here focus on the gap formation by separating satellite migration with fixing the satellite orbit in a Keplerian circular orbit. We reveal how the striking gap features - the density waves, sharp edge, and vertical wall structure - are simultaneously formed by an interplay of the satellite-ring and ring particle-particle interactions. In particular, we propose a new mechanism to quantitatively explain the creation of the vertical wall structure at the gap edge. Inelastic collisions between ring particles damp their eccentricity excited by the satellite's perturbations to enhance the surface density at the gap edge, making its sharp edges more pronounced. We find the eccentricity damping process inevitably raises the vertical wall structures the most effectively in the second epicycle waves. Particle-particle collisions generally convert their lateral epicyclic motion into vertical motion. Because the excited epicyclic motion is the greatest near the ring edge and the epicycle motions are aligned in the first waves, the conversion is the most efficient in the gap edge of the second waves and the wall height is scaled by the satellite Hill radius, which are consistent with the observations.

Classifying the morphologies of radio galaxies is important to understand their physical properties and evolutionary histories. A galaxy's morphology is often determined by visual inspection, but as survey size increases robust automated techniques will be needed. Deep neural networks are an attractive method for automated classification, but have many free parameters and therefore require extensive training data and are subject to overfitting and generalization issues. We explore hybrid classification methods using the scattering transform, the recursive wavelet decomposition of an input image. We analyse the performance of the scattering transform for the Fanaroff-Riley classification of radio galaxies with respect to CNNs and other machine learning algorithms. We test the robustness of the different classification methods with training data truncation and noise injection, and find that the scattering transform can offer competitive performance with the most accurate CNNs.

We report on our new calculations of unified line profiles of K perturbed by He using ab initio potential data for the conditions prevailing in cool substellar brown dwarfs and hot dense planetary atmospheres with temperatures from $T_\mathrm{eff}$=500~$\ \mathrm{K}$ to 3000~$\ \mathrm{K}$. For such objects with atmospheres of H$_2$ and He, conventional laboratory absorption spectroscopy can be used to examine the line wings and test the line shape theories and molecular potentials. We find that an analytical Lorentzian profile is useful for a few cm$^{-1}$ from the line center, but not in the line wings, where the radiative transfer is a consequence of the K-He radiative collisions that are sensitive to the interaction potentials. Tables of the K--He absorption coefficients of the resonance lines allow accurate model atmospheres and synthetic spectra. For this purpose, we present new opacities from comprehensive line shape theory incorporating accurate ab initio potentials. Use of these new tables for the modeling of emergent spectra will be an improvement over previous line shape approximations based on incomplete or inaccurate potentials. We also present Lorentzian impact parameters obtained in the semi-classical and quantum theory for the K $4s-4p$ resonance line centered at 0.77~$\mu$m specifically for the line core regime.

Knowledge on the inter-spacecraft optical paths (i.e. delays) is one of the key elements of time delay interferometry (TDI). Conventional method for inter-spacecraft ranging mainly relies on the pseudo-random noise (PRN) code signal modulated onto the lasers. To ensure the reliability and robustness of this ranging information, it would be highly beneficial to develop other methods which could serve as cross-validations or backups. This paper explores the practical implementation of an alternative data-driven approach - time delay interferometry ranging (TDIR) - as a ranging technique independent of the PRN signal. Distinguished from previous research, the inputs of our TDIR algorithm are interferometric measurements that have only undergone a 0.1 ms accuracy preliminary clock synchronization using the ground tracking data. This significantly relaxes the stringent requirement for clock synchronization imposed by traditional TDI procedure. In order to encode the information of time-varying light travel times and clock desynchronizations, we adopt a general polynomial parametrization to represent the delays. By framing TDIR as a Bayesian parameter estimation problem, we demonstrate our algorithm with simulated data based on the numerical orbit of Taiji. In the presence of laser frequency noise and secondary noises, the estimated median values of parameters exhibit a bias of only 5.28 ns from the ''true'' delays, capable of suppressing laser frequency noise to the desired level. Furthermore, we have also analysed the requirements of mitigating optical bench noise and clock noise on TDIR, and presented an illustrative example for the impact of laser locking.

The intra-cluster medium is prone to turbulent motion that will contribute to the non-thermal heating of the gas, complicating the use of galaxy clusters as cosmological probes. Indirect approaches can estimate the intensity and structure of turbulent motions by studying the associated fluctuations in gas density and X-ray surface brightness. In this work, we want to constrain the gas density fluctuations at work in the CHEX-MATE sample to obtain a detailed view of their properties in a large population of clusters. We use a simulation-based approach to constrain the parameters of the power spectrum of density fluctuations, assuming a Kolmogorov-like spectrum and including the sample variance, further providing an approximate likelihood for each cluster. This method requires clusters to be not too disturbed, as fluctuations can originate from dynamic processes such as merging. Accordingly, we remove the less relaxed clusters (centroid shift $w>0.02$) from our sample, resulting in a sample of 64 clusters. We define different subsets of CHEX-MATE to determine properties of density fluctuations as a function of dynamical state, mass and redshift, and investigate the correlation with the presence or not of a radio halo. We found a positive correlation between the dynamical state and density fluctuation variance, a non-trivial behaviour with mass and no specific trend with redshift or the presence/absence of a radio halo. The injection scale is mostly constrained by the core region. The slope in the inertial range is consistent with Kolmogorov theory. When interpreted as originating from turbulent motion, the density fluctuations in $R_{500}$ yield an average Mach number of $M_{3D}\simeq 0.4\pm 0.2$, an associated non-thermal pressure support of $ P_{turb}/P_{tot}\simeq (9\pm 6) \%$ or a hydrostatic mass bias $b_{turb}\simeq 0.09\pm 0.06$, in line with what is expected from the literature.

Stellar binaries are ubiquitous in the galaxy and a laboratory for astrophysical effects. We use TESS to study photometric modulations in the lightcurves of 162 unequal mass eclipsing binaries from the EBLM (Eclipsing Binary Low Mass) survey, comprising F/G/K primaries and M-dwarf secondaries. We detect modulations on 81 eclipsing binaries. We catalog the rotation rates of the primary star in 69 binaries and discover 17 ellipsoidal variables. In a large portion (at least $\sim 51\%$) of our sample, we detect photometric modulations consistent with two over-densities of spots on the primary star that are roughly $180^{\circ}$ apart. We show that these so-called active longitudes are preferentially at the sub- and anti-stellar points on the primary star. Physically, this means that the spots on the primary star preferentially face directly towards and away from the secondary star.

We investigated the theoretical biases affecting the asteroseismic grid-based estimates of stellar parameters in the presence of a mismatch between the heavy element mixture of observed stars and stellar models. We performed a controlled simulation adopting effective temperature, [Fe/H], average large frequency spacing, and frequency of maximum oscillation power as observational constraints. Synthetic stars were sampled from grids of stellar models computed with different [alpha/Fe] values from 0.0 to 0.4. The mass, radius, and age of these objects were then estimated by adopting a grid of models with a fixed [alpha/Fe] value of 0.0. The experiment was repeated assuming different sets of observational uncertainties. In the reference scenario, we adopted an uncertainty of 1.5% in seismic parameters, 50 K in effective temperature, and 0.05 dex in [Fe/H]. A higher uncertainty in the atmospheric constraints was also adopted in order to explore the impact on the precision of the observations of the estimated stellar parameters. Our simulations showed that estimated parameters are biased up to 3% in mass, 1.5% in radius, and 4% in age when the reference uncertainty scenario was adopted. These values correspond to 45%, 48%, and 16% of the estimated uncertainty in the stellar parameters. These biases in mass and radius disappear when adopting larger observational uncertainties because of the possibility of the fitting algorithm exploring a wider range of possible solutions. However, in this scenario, the age is significantly biased by -8%. Finally, we verified that the stellar mass, radius, and age can be estimated with a high accuracy by adopting a grid with the incorrect value of [alpha/Fe] if the metallicity [Fe/H] of the target is adjusted to match the Z in the fitting grid. In this scenario, the maximum bias in the age was reduced to 1.5%.

The results of spectral observations in the $\sim 84-92$ GHz frequency range of six objects in the southern sky containing dense cores and associated with regions of massive stars and star clusters formation are presented. The observations were carried out with the MOPRA-22m radio telescope. Within the framework of the local thermodynamic equilibrium (LTE) approximation, the column densities and abundances of the H$^{13}$CN, H$^{13}$CO$^+$, HN$^{13}$C, HC$_3$N, c-C$_3$H$_2$, SiO, CH$_3$C$_2$H and CH$_3$CN molecules are calculated. Estimates of kinetic temperatures ($\sim 30-50$ K), sizes of emission regions ($\sim 0.2-3.1$ pc) and virial masses ($\sim 70-4600~M_{\odot}$) are obtained. The line widths in the three cores decrease with increasing distance from the center. In four cores, asymmetry in the profiles of the optically thick lines HCO$^+$(1-0) and HCN(1-0) is observed, indicating the presence of systematic motions along the line of sight. In two cases, the asymmetry can be caused by contraction of gas. The model spectral maps of HCO$^+$(1-0) and H$^{13}$CO$^+$(1-0), obtained within the framework of the non-LTE spherically symmetric model, are fitted into the observed ones. The radial profiles of density ($\propto r^{-1.6}$), turbulent velocity ($\propto r^{-0.2}$), and contraction velocity ($\propto r^{0.5}$) in the G268.42--0.85 core have been calculated. The contraction velocity profile differs from that expected both in the case of free fall of gas onto a protostar ($\propto r^{-0.5}$), and in the case of global core collapse (contraction velocity does not depend on distance). A discussion of the obtained results is provided.

The Tip of the Red Giant Branch (TRGB)-based distance method in the I band is one of the most efficient and precise techniques for measuring distances to nearby galaxies (D <= 15 Mpc). The TRGB in the near infrared (NIR) is 1 to 2 magnitudes brighter relative to the I band, and has the potential to expand the range over which distance measurements to nearby galaxies are feasible. Using Hubble Space Telescope (HST) imaging of 12 fields in 8 nearby galaxies, we determine color-based corrections and zero points of the TRGB in the Wide Field Camera 3 IR (WFC3/IR) F110W and F160W filters. First, we measure TRGB distances in the I band equivalent Advanced Camera System (ACS) F814W filter from resolved stellar populations with the HST. The TRGB in the ACS F814W filter is used for our distance anchor and to place the WFC3/IR magnitudes on an absolute scale. We then determine the color dependence (a proxy for metallicity/age) and zero point of the NIR TRGB from photometry of WFC3/IR fields which overlap with the ACS fields. The new calibration is accurate to ~1% in distance, relative to the F814W TRGB. Validating the accuracy of the calibrations, we find that the distance modulus for each field using the NIR TRGB calibration agrees with the distance modulus of the same fields as determined from the F814W TRGB. This is a JWST preparatory program and the work done here will directly inform our approach to calibrating the TRGB in JWST NIRCam and NIRISS photometric filters.

The CLEAN algorithm, first published by H\"{o}gbom and its later variants such as Multiscale CLEAN (msCLEAN) by Cornwell, has been the most popular tool for deconvolution in radio astronomy. Interferometric imaging used in aperture synthesis radio telescopes requires deconvolution for removal of the telescopes point spread function from the observed images. We have compared source fluxes produced by different implementations of H\"{o}gbom and msCLEAN (WSCLEAN, CASA) with a prototype implementation of H\"{o}gbom and msCLEAN for the Square Kilometer Array (SKA) on two datasets. First is a simulation of multiple point sources of known intensity using H\"{o}gbom, where none of the software packages detected all the simulated point sources to within 1.0% of the simulated values. The second is of supernova remnant G055.7+3.4 taken by the Karl G. Jansky Very Large Array (VLA) using msCLEAN, where each of the software packages produced different images for the same settings.

Automated methods for classifying extragalactic objects in large surveys offer significant advantages compared to manual approaches in terms of efficiency and consistency. However, the existence of the Galactic disk raises additional concerns. These regions are known for high levels of interstellar extinction, star crowding, and limited data sets and studies. In this study, we explore the identification and classification of galaxies in the Zone of Avoidance (ZoA). In particular, we compare our results in the near-infrared with X-ray data. We analize the appearance of the objects classified as galaxies using machine learning by Zhang et al. (2021) in the Galactic disk and make a comparison with the visually confirmed galaxies from the VVV NIRGC (Baravalle et al. (2021). Our analysis, which includes the visual inspection of all sources catalogued as galaxies throughout the Galactic disk using machine learning techniques reveals significant differences. Only 4 galaxies were found in both the near-Infrared and X-ray data sets. Several specific regions of interest within the ZoA exhibit a high probability of being galaxies in X-ray data but closely resemble extended Galactic objects. The results indicate the difficulty of using machine learning methods for galaxy classification in the ZoA mainly due to the scarce information on galaxies behind the Galactic plane in the training set. They also stress the importance of considering specific factors that are present to improve the reliability and accuracy of future studies in this challenging region.

We leverage recent numerical simulations of highly resolved star-forming regions in a Milky Way-like Galaxy to explore the nature of extended gaseous envelopes around molecular clouds. We extract a sample of two dozen star-forming clouds from the feedback-dominated suite of the "Cloud Factory'' simulations. With the goal of exploring the 3D thermal and chemical structure of the gas, we measure and fit the clouds' radial profiles in multiple tracers, including $n_{H_I}$, $n_{H_2}$, $n_{H_{tot}}$, $n_{CO}$, and gas temperature. We find that while solar neighborhood clouds recently detected via 3D dust mapping have radially symmetric, low-density envelopes that extend $\sim$ 10-15 pc, the simulated cloud envelopes are primarily radially asymmetric with low-density envelopes that extend only $\sim$ 2-3 pc. One potential explanation for the absence of extended envelopes in the simulated clouds may be the lack of magnetic fields, while a stronger local feedback prescription compared to solar neighborhood conditions may drive the radially asymmetric cloud morphologies. We make the pipeline to extract and characterize the radial profile of clouds publicly available, which can be used in complementary and future simulations to shed additional light on the key physics shaping the formation and evolution of star-forming structures in the Milky Way.

Galaxy submillimetre number counts are a fundamental measurement in our understanding of galaxy evolution models. Most early measurements are obtained via single-dish telescopes with substantial source confusion, whereas recent interferometric observations are limited to small areas. We used a large database of ALMA continuum observations to accurately measure galaxy number counts in multiple (sub)millimetre bands, thus bridging the flux density range between single-dish surveys and deep interferometric studies. We continued the Automated Mining of the ALMA Archive in the COSMOS Field project (A3COSMOS) and extended it with observations from the GOODS-South field (A3GOODSS). The database consists of ~4,000 pipeline-processed continuum images from the public ALMA archive, yielding 2,050 unique detected sources. To infer galaxy number counts, we constructed a method to reduce the observational bias inherent to targeted pointings that dominate the database. This method comprises a combination of image selection, masking, and source weighting. The effective area was calculated by accounting for inhomogeneous wavelengths, sensitivities, and resolutions and for spatial overlap between images. We tested and calibrated our method with simulations. We obtained the first number counts derived in a consistent and homogeneous way in four different ALMA bands covering a relatively large area. The results are consistent with number counts from the literature within the uncertainties. We extended the available depth in ALMA Band 4 by 0.4 dex with respect to previous studies. In Band 7, at the depth of the inferred number counts, ~40% of the cosmic infrared background is resolved into discrete sources. This fraction, however, decreases with wavelength, reaching ~4% in Band 3. Finally, we used the number counts to test models of dusty galaxy evolution, and find a good agreement within the uncertainties.

Absorption of light is one of the main selection effects limiting our ability to detect celestial sources, and ultimately, appearance of the sky across most of the electromagnetic spectrum. Recent advances in quantity and quality of available observational data and analysis methods led to major improvements in resolution, depth and fidelity of 3D dust distribution and extinction maps. The Galactic plane remains, however, essentially ``terra incognita'' beyond distances of a few kilo-parsecs due to the strong absorption in optical and near-infrared bands. Here I attempt to address this issue and present a 3D-$N_{\rm H}$-tool to estimate line of sight reddening and X-ray absorption column combining state of the art optical extinction and dust emission maps, and the results of dispersion measure modeling based on radio pulsar observations. The resulting maps are calibrated using independent absorption tracers and are accessible to general community via a convenient web-interface and full data cube.

We present first results derived from the largest collection of contemporaneously recorded Jovian sodium nebula and Io plasma torus (IPT) in [S II] 673.1 nm images assembled to date. The data were recorded by the Planetary Science Institute's Io Input/Output observatory (IoIO) and provide important context to Io geologic and atmospheric studies as well as the Juno mission and supporting observations. Enhancements in the observed emission are common, typically lasting 1 -- 3 months, such that the average flux of material from Io is determined by the enhancements, not any quiescent state. The enhancements are not seen at periodicities associated with modulation in solar insolation of Io's surface, thus physical process(es) other than insolation-driven sublimation must ultimately drive the bulk of Io's atmospheric escape. We suggest that geologic activity, likely involving volcanic plumes, drives escape.

We present a new determination of the evolving galaxy UV luminosity function (LF) over the redshift range $8.5<z<15.5$ using a combination of several major Cycle-1 JWST imaging programmes - PRIMER, JADES and NGDEEP. This multi-field approach yields a total of $\simeq370$ sq. arcmin of JWST/NIRCam imaging, reaching (5-$\sigma$) depths of $\simeq30$ AB mag in the deepest regions. We select a sample of 2548 galaxies with a significant probability of lying at high redshift ($p(z>8.5)>0.05$) to undertake a statistical calculation of the evolving UV LF. Our new measurements span $\simeq4$ magnitudes in UV luminosity at $z=9-12.5$, placing new constraints on both the shape and evolution of the LF at early times. We fit our observational data-points with a double-power law (DPL) function and explore the evolution of the DPL parameters. Our UV LF measurements yield a new estimate of the early evolution of cosmic star-formation rate density ($\rho_{\rm{SFR}}$) which confirms the gradual, log-linear decline deduced from early JWST studies, at least out to $z \simeq 12$. Finally we show that the observed early evolution of the galaxy UV LF (and $\rho_{\rm{SFR}}$) can be reproduced in a ${\rm \Lambda}$CDM Universe, with no change in dust properties or star-formation efficiency required out to $z \simeq 12$. Instead, we show that a progressive trend towards younger stellar population ages can reproduce the observations, and we show that the typical ages required at $z \simeq$ 8, 9, 10, and 11 all converge on a time $\simeq 380-330$ Myr after the Big Bang, indicative of a rapid emergence of early galaxies at $z \simeq 12 - 13$. This is consistent with the first indications of a steeper drop-off in the galaxy population we find beyond $z \simeq 13$, possibly reflecting the rapid evolution of the halo mass function at earlier times.

In this study, we search for Globular Clusters (GCs) in the inner halo of the Circinus galaxy using a combination of observational data. Our dataset includes observations from the VISTA Variables in the V\'ia L\'actea Extended Survey (VVVX), optical data from Gaia Release 3 (DR3), and observations from the Dark Energy Camera (DECam). These multiple data sources provide a comprehensive basis for our analysis. Our search was concentrated within a 50 kpc radius from the centre, leading to the identification of 93 sources that met our established criteria. To ensure the reliability of our findings, we conducted multiple examinations for sample contamination. These examinations incorporated tests based on Gaia Astrometric Excess Noise (AEN), the Blue Photometer (BP)/Red Photometer (RP) Excess Factor (BRexcess), as well as comparisons with stellar population models. This analysis confidently classified 41 sources as genuine GCs, as they successfully passed both the 3$\sigma$ Gaia AEN and BRexcess tests. We used the ISHAPE program to determine the structural parameters (half-light radii) of the GC candidates, with a peak effective radius of 4$\pm$ 0.5 pc. The catalogue mainly consists of bright GCs. Relationships between colour, size, and distance were found in the GC candidates, alongside confirmation of bi-modality in colour distributions.

We present rest-frame optical data of the z~4 sub-millimeter galaxy GN20 obtained with JWST/NIRSpec in integral field spectroscopy (IFS) mode. The H$\alpha$ emission is asymmetric and clumpy and extends over a projected distance of more than 15 kpc. To first order, the large-scale ionised gas kinematics are consistent with a turbulent ($\sigma\sim90$ km/s), rotating disc ($v_{\rm rot}\sim500$ km/s), congruent with previous studies of its molecular and ionised gas kinematics. However, we also find clear evidence for non-circular motions in the H$\alpha$ kinematics. We discuss their possible connection with various scenarios, such as external perturbations, accretion or radial flows. In the centre of GN20, we find broad line emission (FWHM $\sim1000-2000$ km/s) in the H$\alpha$+[N II] complex, suggestive of fast, AGN-driven winds or, alternatively, of the broad-line region of an active black hole. Elevated values of [N II]$\lambda6583$/H$\alpha>0.4$ and EW(H$\alpha)>6$ \r{A}, throughout large parts of GN20 suggest that feedback from the active black hole is able to photo-ionise the interstellar medium. Our data corroborates that GN20 offers a unique opportunity to observe key processes in the evolution of the most massive present-day galaxies acting in concert, over 12 billion years ago.

Cosmological models featuring an elastic interaction in the dark sector at linear order has been shown to provide a promising scenario for alleviating the $\sigma_8$ tension. A natural question for these scenarios is whether there could be a degeneracy between the interaction and massive neutrinos that also contribute to erasing structures at late times. In this work we investigate the presence of such a degeneracy and show that the two effects do not exhibit strong correlations.

We present optimal Bayesian field-level cosmological constraints from nonlinear tracers of the large-scale structure, specifically the amplitude $\sigma_8$ of linear matter fluctuations inferred from rest-frame simulated dark matter halos in a comoving volume of $8\,(h^{-1}\mathrm{Gpc})^3$. Our constraint on $\sigma_8$ is entirely due to nonlinear information, and obtained by explicitly sampling the initial conditions along with bias and noise parameters via a Lagrangian EFT-based forward model, LEFTfield. The comparison with a simulation-based inference analysis employing the power spectrum and bispectrum likewise using the LEFTfield forward model shows that, when including precisely the same modes of the same data up to $k_{\mathrm{max}}= 0.10\,h\,\mathrm{Mpc}^{-1}$ ($0.12\,h\,\mathrm{Mpc}^{-1}$), the field-level approach yields a factor of 1.7 (2.6) improvement on the $\sigma_8$ constraint, from 9.9% to 5.8% (9.4% to 3.6%). This study provides the first direct insights into cosmological information encoded in galaxy clustering beyond low-order $n$-point functions.

(Ultra)light spin-$1$ particles - dark photons - can constitute all of dark matter (DM) and have beyond Standard Model couplings. This can lead to a coherent, oscillatory signature in terrestrial detectors that depends on the coupling strength. We provide a signal analysis and statistical framework for inferring the properties of such DM by taking into account (i) the stochastic and (ii) the vector nature of the underlying field, along with (iii) the effects due to the Earth's rotation. On time scales shorter than the coherence time, the DM field vector typically traces out a fixed ellipse. Taking this ellipse and the rotation of the Earth into account, we highlight a distinctive three-peak signal in Fourier space that can be used to constrain DM coupling strengths. Accounting for all three peaks, we derive latitude-independent constraints on such DM couplings, unlike those stemming from single-peak studies. We apply our framework to the search for ultralight $B - L$ DM using optomechanical sensors, demonstrating the ability to delve into previously unprobed regions of this DM candidate's parameter space.

We study the role of an ultra-light primordial black hole (PBH) dominated phase on the generation of baryon asymmetry of the Universe (BAU) and dark matter (DM) in a type-I seesaw framework augmented by Peccei-Quinn (PQ) symmetry which solves the strong CP problem. While the BAU is generated via leptogenesis from the decay of heavy right-handed neutrino (RHN) at the seesaw scale dictated by the PQ scale, DM can arise either from QCD axion or one of the RHNs depending upon the PQ scale. The ultra-light PBH not only affects the axion DM production via misalignment mechanism, but can also produce superheavy RHN DM via evaporation. Depending upon the PBH parameters and relative abundance of axion DM, axion mass can vary over a wide range from sub-$\mu$eV to sub-eV keeping the detection prospects promising across a wide range of experiments. While hot axions produced from PBH evaporation can lead to observable $\Delta N_{\rm eff}$ to be probed at future cosmic microwave background (CMB) experiments, stochastic gravitational waves (GW) produced from PBH density fluctuations can be observed at future detectors like CE, DECIGO, LISA and even future runs of LIGO-VIRGO.

We show that the existence of clouds of ultralight particles surrounding black holes during their cosmological history as members of a binary system can leave a measurable imprint on the distribution of masses and orbital eccentricities observable with future gravitational-wave detectors. Notably, we find that for nonprecessing binaries with chirp masses ${\cal M} \lesssim 10\,M_\odot$, formed exclusively in isolation, larger-than-expected values of the eccentricity, i.e. $e\gtrsim 10^{-2}$ at gravitational-wave frequencies $f_{\rm GW} \simeq 10^{-2}\,$Hz, would provide tantalizing evidence for a new particle of mass between $[0.5,2.5] \times 10^{-12}\,$eV in nature. The predicted evolution of the eccentricity can also drastically affect the in-band phase evolution and peak frequency. These results constitute unique signatures of boson clouds of ultralight particles in the dynamics of binary black holes, which will be readily accessible with the Laser Interferometer Space Antenna, as well as future mid-band and Deci-hertz detectors.

Within the context of Rastall gravity, we investigate the hydrostatic equilibrium and dynamical stability against radial pulsations of compact stars, where a free parameter $\beta$ measures the deviations from General Relativity (GR). We derive both the modified Tolman-Oppenheimer-Volkoff (TOV) equations and the Sturm-Liouville differential equation governing the adiabatic radial oscillations. Such equations are solved numerically in order to obtain the compact-star properties for two realistic equations of state (EoSs). For hadronic matter, the fundamental mode frequency $\omega_0$ becomes unstable almost at the critical central energy density corresponding to the maximum gravitational mass. However, for quark matter, where larger values of $\vert\beta\vert$ are required to observe appreciable changes in the mass-radius diagram, there exist stable stars after the maximum-mass configuration for negative values of $\beta$. Using an independent analysis, our results reveal that the emergence of a cusp can be used as a criterion to indicate the onset of instability when the binding energy is plotted as a function of the proper mass. Specifically, we find that the central-density value where the binding energy is a minimum corresponds precisely to $\omega_0^2 =0$.

Extrapolating the Standard Model Higgs potential at high energies, we study the barrier between the electroweak and Planck scale minima. The barrier arises by taking the central values of the relevant experimental inputs, that is the strong coupling constant and the top quark and Higgs masses. We then extend the Standard Model by including a non-minimal coupling to gravity, and explore the phenomenology of the Higgs inflation model. We point out that even configurations that would be metastable in the Standard Model, become viable for inflation if the non-minimal coupling is large enough to flatten the Higgs potential at field values below the barrier; we find that the required value of the non-minimal coupling is smaller than the one needed for the conventional Higgs inflation scenario (which relies on a stable Standard Model Higgs potential, without any barrier); in addition, values of the top mass which are slightly larger than those required in the conventional scenario are allowed.

We present a statistical investigation of the radial evolution of 28 interplanetary coronal mass ejections (ICMEs), measured in situ by the Parker Solar Probe (PSP) spacecraft from 2018 October to 2022 August. First, by analyzing the radial distribution of ICME classification based on magnetic hodograms, we find that coherent configurations are more likely to be observed close to the Sun. In contrast, more complex configurations are observed farther out. We also notice that the post-ICME magnetic field is more impacted following an ICME passage at larger heliocentric distances. Second, with a multi-linear robust regression, we derive a slower magnetic ejecta (ME) expansion rate within 1~au compared to previous statistical estimates. Then, investigating the magnetic field fluctuations within ICME sheaths, we see that these fluctuations are strongly coupled to the relative magnetic field strength gradient from the upstream solar wind to the ME. Third, we identify ME expansion as an important factor in forming sheaths. Finally, we determine the distortion parameter (DiP) which is a measure of magnetic field asymmetry in an ME. We discover lower overall asymmetries within MEs. We reveal that even for expanding MEs, the time duration over which an ME is sampled does not correlate with DiP values, indicating that the aging effect is not the sole contributor to the observed ME asymmetries.

In this paper, we would like to examine whether stable de Sitter inflationary solutions appear within power-law extensions of the Starobinsky model. In particular, we will address general constraints for the existence along with the stability of de Sitter inflationary solutions in a general case involving not only the Starobinsky $R^2$ term but also an additional power-law $R^n$ one. According to the obtained results, we will be able to identify which extension is more suitable for an early inflationary phase rather than a late-time cosmic acceleration phase. To be more specific, we will consider several values of $n$ to see whether the corresponding de Sitter inflationary solutions are stable or not.

Cosmic ray muons prove valuable across various fields, from particle physics experiments to non-invasive tomography, thanks to their high flux and exceptional penetrating capability. Utilizing a scintillator detector, one can effectively study the topography of mountains situated above tunnels and underground spaces. The Hankuk Atmospheric-muon Wide Landscaping (HAWL) project successfully charts the mountainous region of eastern Korea by measuring cosmic ray muons with a detector in motion. The real-time muon flux measurement shows a tunnel length accuracy of 6.5 %, with a detectable overburden range spanning from 8 to 400 meter-water-equivalent depth. This is the first real-time portable muon tomography.

There is limited information about interaction strength of scalar dark matter candidate with hadrons and leptons for scalar particle mass exceeding $10^{-3}$ eV while its interaction with photon is well-studied. The scalar-photon coupling constant receives quantum corrections from one-loop Feynman diagrams which involve the scalar-lepton, scalar-quark and scalar-W boson vertices. We calculate these one-loop quantum corrections and find new limits on the scalar particle interactions with electron, muon, tau, quarks, nucleons, gluons and W boson for $m_{\phi}<15$ MeV by re-purposing the results of experiments measuring the scalar-photon interaction. Limits on interactions with heavy leptons and quarks have been obtained for the first time, limits on other interactions in certain mass intervals are 2 to 15 orders of magnitude stronger than those presented in previous publications.

This study explores a minimal renormalizable dark matter (DM) model, incorporating a sub-GeV Majorana DM and a singlet scalar particle $\phi$. Using scalar and pseudo-scalar interactions (couplings $c_s$ and $c_p$), we investigate implications for DM detection, considering $s$-wave, $p$-wave, and combined ($s$+$p$ wave) contributions in DM annihilation cross-section, as well as loop-correction contributions to DM-nucleon elastic scattering. Identifying a broad parameter space ($10 \,\rm{MeV} < m_\chi \lesssim m_\phi$) within the $2\sigma$ allowed region, we explore scenarios ($\left|c_s\right|\gg \left|c_p\right|$, $\left|c_s\right|\ll \left|c_p\right|$, and $\left|c_s\right|\approx \left|c_p\right|$). We find that (i) a non-zero pseudo-scalar coupling alleviates direct detection constraints as a comparison with the previous pure scalar coupling case; (ii) CMB observations set stringent limits on pseudo-scalar interaction dominant cases, making $s$-wave annihilation viable only for $m_\chi>1\,\rm{GeV}$; (iii) the preferred $\phi$-resonance region can be tested in the future indirect detection experiments, such as e-ASTROGAM.

The lack of reliable atomic data can be a severe limitation in astrophysical modelling, in particular of events such as kilonovae that require information on all neutron-capture elements across a wide range of ionization stages. Notably, the presence of non-orthonormalities between electron orbitals representing configurations that are close in energy can introduce significant inaccuracies in computed energies and transition probabilities. Here, we propose an explicit targeted optimization method that can effectively circumvent this concern while retaining an orthonormal orbital basis set. We illustrate this method within the framework of small-scale atomic structure models of Au I, using the GRASP2018 multiconfigurational Dirac-Hartree-Fock atomic structure code. By comparing to conventional optimization schemes we show how a targeted optimization approach improves the energy level positioning and ordering. Targeted optimization also leads to better agreement with experimental data for the strongest E1 transitions. This illustrates how small-scale models can be significantly improved with minor computational costs if orbital non-orthonormalities are considered carefully. These results should prove useful to multi-element atomic structure calculations in, for example, astrophysical opacity applications involving neutron-capture elements.

The addition of individual quanta of rotational excitation to a molecule has been shown to markedly change its reactivity by significantly modifying the intermolecular interactions. So far, it has only been possible to observe these rotational effects in a very limited number of systems due to lack of rotational selectivity in chemical reaction experiments. The recent development of rotationally controlled molecular beams now makes such investigations possible for a wide range of systems. This is particularly crucial in order to understand the chemistry occurring in the interstellar medium, such as exploring the formation of carbon-based astrochemical molecules and the emergence of molecular complexity in interstellar space from the reaction of small atomic and molecular fragments.

Polytropic stars are useful tools to learn about the stellar structure without the complexity of comprehensive stellar models. These models rely on a certain power-law correlation between the star's pressure and density. This paper proposes a polytropic star model to investigate some new features in the context of $5\mathcal{D}$ Einstein-Gauss-Bonnet (EGB) gravity using the Finch-Skea {\em ansatz} [{\em M. R. Finch and J. E. Skea, Classical and Quantum Gravity 6, 467 (1989)}]. Analytical results are better described by graphical representations of the physical parameters for various values of the coupling parameter $\alpha$. The solution for a specific compact object, EXO 1785 - 248, with radius $\mathfrak{R} = 8.849_{-0.04}^{+0.04}$ km and mass $\mathcal{M} = 1.3 \pm 0.02~\mathcal{M}_{\odot}$, is shown here. We analyze the essential physical attributes of the star, which reveal the influence of the coupling parameter $\alpha$ on the values of substance parameters. Ultimately, we have concluded that our current model is realistic because it satisfies all the physical criteria for an acceptable model.

Continuous gravitational-wave signals (CWs) are long-lasting quasi-monochromatic gravitational-wave signals expected to be emitted by rapidly-rotating non-axisymmetric neutron stars. Depending on the rotational frequency and sky location of the source, certain CW signals may behave in a similar manner to narrow-band artifacts present in ground-based interferometric detectors. Part of the detector-characterisation tasks in the current generation of interferometric detectors (Advanced LIGO, Advanced Virgo, and KAGRA) aim at understanding the origin of these narrow artifacts, commonly known as ``spectral lines''. It is expected that similar tasks will continue after the arrival of next-generation detectors (e.g. Einstein Telescope and Cosmic Explorer). Typically, a fraction of the observed lines in a given detector can be associated to one or more instrumental causes; others, however, have an unknown origin. In this work, we assess the similarity of CW signals to spectral lines in order to understand whether a CW may be mistaken for a noise artifact. Albeit astrophysically unlikely, our results do not rule out the possibility of a CW signal being visible in the detector's power spectrum.

It has been claimed that matter effects cause an asymmetry in the density of relic neutrinos versus antineutrinos near the surface of Earth, of order $O(G_F^{1/2})\sim 10^{-4}$, with the vertical extent $\sim 10$m. We argue that the effect is of order $O(G_F)\sim 10^{-8}$, with the vertical extent $\sim 1$mm.

We describe the pioneering contributions of Thomas K. Gaisser to the birth and development of particle astrophysics, a new field of research at the intersection of cosmic ray physics, astronomy, astrophysics, and particle physics that has emerged in the last few decades. We will especially focus on his studies of natural beams of neutrinos: those generated by the interactions of cosmic rays in the Earth's atmosphere and those emitted by astrophysical sources. Tom actively participated in the discovery of these cosmic neutrinos as well. His contributions also extend to gamma-ray astronomy, the study of the cosmic ray spectra and composition, and the modeling of cosmic ray interactions in the atmosphere and in astrophysical environments. Tom invariably focused his research on the theoretical and phenomenological problems of greatest interest at the time, producing frameworks that transparently interpreted often complex data. These studies have been very influential and have shaped the development of the field.