Papers for Thursday, Apr 17 2025

The invited review of own algorithms and software (MAVKA and MCV) for the data analysis of astronomical signals - irregularly spaced, multi-periodic multi-harmonic, periodogram analysis and approximations with taking into account a polynomial trend simultaneously, instead of commonle used detrending and prewhitening. The references to original papers are listed.

We conduct high-resolution wind-tunnel simulations to study in-situ star formation in the stripped tails of two massive ($M_\text{star}=10^{11}M_\odot$) galaxies undergoing time-evolving ram-pressure stripping: one is stripped face-on (W0) and the other is subject to an angled wind (W45). We find that the majority of stars in the tail are formed close to the galaxy disc at the beginning of stripping. Most stars have ages that reflect outside-in stripping -- older stars are found at larger radii than younger stars. The velocities and metallicities of stars indicate that ICM mixing both increases the velocity and decreases the metallicity of star-forming gas, leading to faster, lower metallicity stars at larger distances from the galaxies. However, not all stars follow this simple model, even in the case of face-on stripping. Indeed, a considerable number (15--25 per cent) of tail stars are formed with negative velocities, indicating the fallback of star-forming gas on to the galaxy. Almost all of the tail stars formed within 20 kpc from the disc will eventually fall back on to the galaxy, and their contribution to the intracluster light is negligible. The orbits of the stars formed in the tail result in an extended (and asymmetric in the case of W45) stellar distribution around the disc. Mock UV images reveal that the observed vertical distribution of its stars is not significantly broader than in an undisturbed galaxy, indicating that more stars would need to form in the stripped tail than we find in our simulations to observably impact the UV disc width of ram pressure stripped galaxies.

A star's ability to explode in a core-collapse supernova is correlated with its density profile, $\rho(r)$, such that compact stars with shallow density profiles preferentially ``fail'' and produce black holes. This correlation can be understood from a mass perspective, as shallower density profiles enclose $\sim 3M_{\odot}$ (i.e., the maximum neutron-star mass) at relatively small radii, but could also be due to the fact that a shockwave (driving the explosion) inevitably stalls if the density profile into which it propagates is shallower than $\rho(r) \propto r^{-2}$. Here we show that this condition -- the density profile being steeper than $\rho \propto r^{-2}$ -- is necessary, but not sufficient, for generating a strong explosion. In particular, we find solutions to the fluid equations that describe a shockwave propagating at a fixed fraction of the local freefall speed into a temporally evolving, infalling medium, the density profile of which scales as $\rho \propto r^{-n}$ at large radii. The speed of the shock diverges as $n\rightarrow 2$ and declines (eventually to below the Keplerian escape speed) as $n$ increases, while the total energy contained in the explosion approaches zero as the shock recedes to large distances. These solutions therefore represent fluid-dynamical analogs of marginally bound orbits, and yield the ``shock escape speed'' as a function of the density profile. We also suggest that stellar explodability is correlated with the power-law index of the density at $\sim10^9$ cm, where the neutrino diffusion time equals the local dynamical time for most massive stars, which agrees with supernova simulations.

Gaia parallax measurements for stars with poor astrometric fits -- as evidenced by high renormalized unit weight error (RUWE) -- are often assumed to be unreliable, but the extent and nature of their biases remain poorly quantified. High RUWE is usually a consequence of binarity or higher-order multiplicity, so the parallaxes of sources with high RUWE are often of greatest astrophysical interest. Using realistic simulations of Gaia epoch astrometry, we show that the parallax uncertainties of sources with elevated RUWE are underestimated by a factor that ranges from 1 to 4 and can be robustly predicted from observables. We derive an empirical prescription to inflate reported uncertainties based on a simple analytic function of RUWE, apparent magnitude, and parallax. We validate the correction using (a) single-star solutions for Gaia sources with known orbital solutions and (b) wide binaries containing one component with elevated RUWE. The same uncertainty corrections are expected to perform well in DR4 and DR5. Our results demonstrate that Gaia parallaxes for high-RUWE sources can still yield robust distance estimates if uncertainties are appropriately inflated, enabling distance constraints for triples, binaries with periods too long or too short to be fit astrometrically, and sources blended with neighboring sources.

Modern astronomical surveys, such as the Zwicky Transient Facility (ZTF), are capable of detecting thousands of transient events per year, necessitating the use of automated and scalable data analysis techniques. Recent advances in machine learning have enabled the efficient classification and characterization of these transient phenomena. We aim to develop a fully systematic pipeline to identify candidate stellar collision events in galactic nuclei, which may otherwise be identified as tidal disruption events or other transients. We also seek to validate our simulations by comparing key physical parameters derived from observations and used in modeling these events. We generate a comprehensive bank of simulated light curves spanning a range of physical parameters and employ an approximate nearest neighbor algorithm (via the annoy library) to match these with observed ZTF light curves. Our pipeline is successfully able to associate observed ZTF light curves with simulated events. The resulting estimated parameters, including supermassive black hole masses and ejecta mass, are presented and compared to known values when applicable. We demonstrate that a systematic, machine learning-based approach can effectively identify and characterize stellar collision candidate events from large-scale transient surveys. This methodology is especially promising for future surveys which will provide us with significantly high volumes of data, such as LSST, where automated, data-intensive analysis will be critical for advancing our understanding of transient astrophysical phenomena.

Extended emission line nebulae around galaxies or active galactic nuclei (AGNs) provide a unique window to investigate the galactic ecosystem through the circumgalactic medium (CGM). Using Subaru Hyper-Suprime Cam narrow-band imaging and spectroscopic follow-up, we serendipitously discover "Oxyster" - a large ionized nebula next to an interacting starburst galaxy at $z=0.924$. The nebula is traced by extended [OII]3726,3729 ($\sim 30$ kpc) and [OIII]5007 ($\sim 20$ kpc) emission lines. On the nebula luminosity-size plane, Oxyster surpasses the extended narrow-line regions around low-$z$ AGNs, resembling a higher-$z$ analog of "Hanny's Voorwerp". However, its uniformly low [OIII]/[OII] ratio (O32) sets it apart from typical AGN light echoes. For the host galaxy, HST and JWST images reveal a disturbed red disk galaxy with a single blue spiral "arm". Spectral energy distribution (SED) fitting suggests the $2-6\times 10^{10} ~\rm M_{\odot}$ host galaxy sits above the star-forming main sequence with an ongoing starburst, especially in the "arm", and have $<5\%$ luminosity contribution from AGN, consistent with X-ray non-detection and radio continuum. Standard photoionization and shock models struggle to explain simultaneously Oxyster's emission line luminosities, low O32 ratio, and the non-detection of H$\beta$ line. A plausible explanation could involve the combination of a recent ($<10^8$ yrs) starburst and a low-luminosity AGN ($L_{\rm{bol}} \sim 1\times10^{42}$ erg/s). While Oxyster's nature awaits future investigation, its discovery highlights the potential of ground-based narrow-band imaging to uncover extended emission line nebulae around non-AGN systems, opening new avenues for studying the CGM of normal galaxies in the early Universe.

We present a series of fully three-dimensional, dynamical-spacetime general relativistic magnetohydrodynamics (GRMHD) simulations of core-collapse supernovae (CCSNe) for a progenitor of zero-age-main-sequence (ZAMS) mass $25\, M_\odot$. We simulate a total of 12 models for simulation times in the range $190-260\, \mathrm{ms}$ to systematically study the effect of rotation rates and magnetic fields on jet formation via the magnetorotational mechanism. We have performed simulations on OLCF's Frontier using the new GPU-accelerated dynamical-spacetime GRMHD code \theCode for magnetic fields $B_0 = (10^{11}, 10^{12})\, \mathrm{G}$ and rotation rates $\Omega_0 = (0.14, 0.5, 1.0, 1.5, 2.0, 2.5)\, \mathrm{rad/s}$. We always resolve the entire region containing the shock with a resolution of at least $1.48\, \mathrm{km}$. We find that models with $B_0=10^{11}\, \mathrm{G}$ fail to explode, while those with $B_0=10^{12}\, \mathrm{G}$ show a wide range of jet morphologies and explosive outcomes depending on the rotation rate. Models with $B_0=10^{12}\, \mathrm{G}$ and $\Omega_0=(1.0,1.5)\, \mathrm{rad/s}$ form jets that bend sideways, giving the ejecta a more spherical character, and possibly representing explosions that \textit{appear} neutrino-driven even though they are magnetorotationally-driven. Models with $B_0=10^{12}\, \mathrm{G}$ and $\Omega_0\geq2.0\, \mathrm{rad/s}$ show ejecta velocities $\gtrsim15000\, \mathrm{km/s}$, making them suitable candidates for broad-lined type Ic supernova progenitors. This work represents the largest set of 3D general-relativistic GRMHD simulations studying magnetorotational supernovae in full GR and demonstrates the potential of systematic studies with GPU-accelerated 3D simulations of CCSNe.

Recently, several observational detections of damping-wing-like features at the edges of ``dark gaps" in the spectra of distant quasars (the ``Malloy-Lidz effect") have been reported, rendering strong support for the existence of ``neutral islands" in the universe at redshifts as low as $z<5.5$. We apply the procedure from one of these works, \citet{YZhu2024}, to the outputs of fully coupled cosmological simulations from two recent large projects, ``Cosmic Reionization On Computers" (CROC) and ``Thesan". Synthetic spectra in both simulations have statistics of dark gaps similar to observations, but do not exhibit the damping wing features. Moreover, a toy model with neutral islands added ``by hand" only reproduces the observational results when the fraction of neutral islands among all dark gaps exceeds 90%. I.e., simulations and observations appear to produce two distinct ``populations" of dark gaps. In addition, the neutral islands observed at $z=5.9$ should be short-lived and hence cannot extend to $z<5.5$. In summary, the observational detections of damping wing features present serious challenges not only to state-of-the-art simulations but also to our general understanding of how reionization should proceed.

The modulation of low-energy galactic cosmic rays reflects interplanetary magnetic field variations and can provide useful information on solar activity. An array of ground-surface detectors can reveal the secondary particles, which originate from the interaction of cosmic rays with the atmosphere. In this work, we present an investigation of the low-threshold rate (scaler) time series recorded in 16 years of operation by the Pierre Auger Observatory surface detectors in Malargue, Argentina. Through an advanced spectral analysis, we detected highly statistically significant variations in the time series with periods ranging from the decadal to the daily scale. We investigate their origin, revealing a direct connection with solar variability. Thanks to their intrinsic very low noise level, the Auger scalers allow a thorough and detailed investigation of the galactic cosmic-ray flux variations in the heliosphere at different timescales and can, therefore, be considered a new proxy of solar variability.

Mixtures of bare atomic nuclei on a nearly uniform degenerate electron background are a realistic model of matter in the interior of white dwarfs. Despite tremendous progress in understanding their phase diagrams achieved mainly via first-principle simulations, structural, thermodynamic, and kinetic properties of such mixtures are poorly understood. We develop a semi-analytic model of the crystal state of binary mixtures based on the concept of mutual short-range ordering of ions of different sorts. We derive analytic formulas for electrostatic energy of crystal mixtures, including the effect of static ion displacements from the lattice nodes, and estimate their residual entropy. Then we perform free energy minimization with respect to the order parameters for a C/O mixture at all relevant compositions and temperatures. The resulting C/O phase diagram is in a reasonable agreement with that obtained in the most recent first-principle study. The equilibrium microstructure of a crystallized mixture is shown to evolve with decrease of temperature which, in principle, can induce structural transitions. The latter will be accompanied by thermal energy release. The proposed theory opens up a path to analyze ordering and construct phase diagrams of ternary mixtures, which are of great practical interest in astrophysics, as well as to improve calcuations of electron-ion scattering rates and kinetic properties of dense crystallized matter.

Microlensing events provide a unique way to detect and measure the masses of isolated, non-luminous objects, particularly dark stellar remnants. Under certain conditions, it is possible to measure the mass of these objects using photometry alone, specifically when a microlensing light curve displays a finite-source (FS) effect. This effect generally occurs in highly magnified light curves, i.e. when the source and the lens are very well aligned. In this study, we analyse Gaia Alerts and Gaia Data Release 3 datasets, identifying four moderate-to-high-magnification microlensing events without a discernible FS effect. The absence of this effect suggests a large Einstein radius, implying substantial lens masses. In each event, we constrain the FS effect and therefore establish lower limits for angular Einstein radius and lens mass. Additionally, we use the DarkLensCode software to obtain mass, distance, and brightness distribution for the lens based on the Galactic model. Our analysis established lower mass limits of $\sim 0.2$ $M_{\odot}$ for one lens and $\sim 0.3-0.5$ $M_{\odot}$ for two others. DarkLensCode analysis supports these findings, estimating lens masses in the range of$\sim 0.42-1.66$ $M_{\odot}$ and dark lens probabilities exceeding 60\%. These results strongly indicate that the lenses are stellar remnants, such as white dwarfs or neutron stars. While further investigations are required to confirm the nature of these lenses, we demonstrate a straightforward yet effective approach to identifying stellar remnant candidates.

Radio telescopes observe extremely faint emission from astronomical objects, ranging from compact sources to large scale structures that can be seen across the whole sky. Satellites actively transmit at radio frequencies (particularly at 10--20\,GHz, but usage of increasing broader frequency ranges are already planned for the future by satellite operators), and can appear as bright as the Sun in radio astronomy observations. Remote locations have historically enabled telescopes to avoid most interference, however this is no longer the case with dramatically increasing numbers of satellites that transmit everywhere on Earth. Even more remote locations such as the far side of the Moon may provide new radio astronomy observation opportunities, but only if they are protected from satellite transmissions. Improving our understanding of satellite transmissions on radio telescopes across the whole spectrum and beyond is urgently needed to overcome this new observational challenge, as part of ensuring the future access to dark and quiet skies. In this contribution we summarise the current status of observations of active satellites at radio frequencies, the implications for future astronomical observations, and the longer-term consequences of an increasing number of active satellites. This will include frequencies where satellites actively transmit, where they unintentionally also transmit, and considerations about thermal emission and other unintended emissions. This work is ongoing through the IAU CPS.

Galaxies grow alongside their central supermassive black holes (SMBHs), linked through fueling and feedback. However, the origins and details of this co-evolution remain unclear and differ significantly amongst modeling frameworks. Using a suite of semi-analytic models (SAMs), we trace SMBH mass assembly across $M_{\rm BH} \sim 10^{6-10}, \mathrm{M}_{\odot}$. We find significant discrepancies between observations and physics-based models of the local black hole mass function (BHMF), likely due to differences in the underlying stellar mass function and the scaling relations therefrom used to infer the BHMF. However, most physics-based models agree at $z \sim 1-4$ and align reasonably well with broad-line AGN BHMF from JWST observations at $z=4-5$. Most physics-based models reproduce the bolometric AGN luminosity evolution, except {\sc Dark Sage}, which predicts an excess deviating from models and observations. Interestingly, this pronounced ``knee' in the bolometric AGN luminosity function predicted by {\sc Dark Sage} around $L_{\rm bol} \sim 10^{46} \, \mathrm{erg \, s^{-1}}$ is consistent with the inferred luminosity of ``Little Red Dots'' at $z=5-6$, assuming that their entire emission originates from AGN activity. We analyze black hole mass build-up and accretion histories in {\sc Dark Sage}, which, unlike other models, allows for super-Eddington accretion. We report that on average, SMBHs in {\sc Dark Sage} primarily grow through secular disk instabilities and merger-driven cold gas accretion, while black hole mergers contribute 60\% of the total mass budget only for the most massive SMBHs by $z=0$.

The 1.3 mm CAMPOS survey has resolved 90 protostellar disks with $\sim$15 au resolution across the Ophiuchus, Corona Australis, and Chamaeleon star-forming regions. To address the fundamental question, "When does planet formation begin?", we combined the CAMPOS sample with literature observations of Class 0-II disks (bolometric temperature, $T_{\rm bol} \le 1900$ K), all mapped at 1.3 mm with resolutions ranging from 4 to 33 au. To investigate substructure detection rates as a function of bolometric temperature, we restricted the sample to disks observed at the 1.3 mm wavelength, with inclinations below 75$^\circ$, linear resolution $\le 20$ au and resolved with at least four resolution elements ($\theta_{\rm disk}/\theta_{\rm res} \ge 4$). We also considered the effects of extinction correction and the inclusion of Herschel Space Telescope data on the bolometric temperature measurements, to constrain the lower and upper limits of bolometric temperature for each source. We find that by $T_{\rm bol} \sim 200-400\,K$, substructure detection rates increased sharply to $\sim$60%, corresponding to an approximate age of $0.2-0.4$ Myr. No substructures are detected in Class 0 disks. The ratio of disk-averaged brightness temperature to predicted dust temperature shows a trend of increasing values toward the youngest Class 0 disks, suggesting higher optical depths in these early stages. Classifying disks with substructures into those with and without large central cavities, we find both populations coexisting across evolutionary stages, suggesting they are not necessarily evolutionarily linked. Our statistical analysis confirms that substructures similar to those in Class II disks are already common by the Class I stage, and the emergence of these structures at $T_{\rm bol} \sim 200-400\,K$ could represent only an upper limit.

Chemodynamical tagging has been suggested as a powerful tool to trace stars back to their birth clusters. However, the efficacy of chemodynamical tagging as a means to recover individual stellar clusters is still under debate. In this study, we present a detailed investigation of chemodynamical tagging of open clusters using both dynamical and chemical data from the \textit{Gaia} DR3 and GALAH DR4 surveys, respectively. Using a sample of open clusters and mock field stars, we conduct a bootstrap analysis to evaluate every unique combination of orbital components ($E, J_R, J_\phi, J_Z$) and chemical abundances ([X/Fe] for O, Na, Mg, Al, Si, K, Ca, Sc, Ti, Cr, Mn, Ni, Cu, Y, and Ba) on how well they recover open clusters when used as parameters in the clustering algorithm, HBDSCAN. We find that using primarily dynamical orbital parameters leads to the highest recovery rate of open cluster stars. Nevertheless, even employing the best performing parameter combinations leads to low open cluster recovery rates. We find that, in most cases, chemodynamical tagging of open clusters using blind clustering algorithms is not efficient, which is in line with previous theoretical and observational work. However, we show that the addition of cuts based on metallicity, age, and birth radii in order to reduce the size of the clustering catalog can marginally improve the recovery rate of open clusters.

Recent discoveries of primordial black hole (PBH) candidates by means of high cadence microlensing open the way to a physical understanding of the formation of dark matter as a chapter in the thermal history of the Universe. Two complementary sites of PBH formation are considered, inflation and the early Universe at TeV to MeV energies. In the latter case the Friedman equation, together with the measurement of the mass of the PBH, reveal the threshold energy, the mass spectrum and the likely end point of this epoch. Some of the many recent exoplanet detections may conceivably have been detections of PBHs. When the Universe cools to MeV temperatures, larger mass PBH would form similarly, reaching the supermassive regime. The discovery of numerous supermassive black holes (SMBH) at high redshift with JWST fulfils this expectation. We corroborate the idea that Planck mass relics could be an important component of dark matter, and find that these are formed by PBH with initial mass less than approximately 6 x 10^{-16} M{_\odot} and cosmic temperature above 10^9 GeV. Although in some mass ranges PBH can only make up a modest fraction of {\Omega}matter, it is possible that all astrophysical dark matter, as distinct from axions and WIMPs, is of PBH origin.

The local universe is still full of hidden dwarf galaxies to be discovered using deep imaging campaigns. Here we present the third paper in a series to search for low-surface brightness dwarf galaxies around nearby isolated luminous host galaxies with the Subaru Hyper Suprime Camera. Based on visual inspection, we found 11, 0, 4, and 6 dwarf galaxy candidates around M106, NGC2903, NGC3521, and UGCA127, respectively. This adds to the 40 candidates around M104 and 4 candidates around NGC2683 found in the previous papers. Artificial galaxy experiments show that we are complete down to a mean effective surface brightness of 26 mag/arcsec$^2$. The new dwarf galaxy candidates follow known scaling relation in size, surface brightness and luminosity, making them good candidates based on their morphology and photometric properties. We trace the luminosity function of these galaxies down to magnitude of $\approx-$9 in the V band for all galaxies targeted in our survey footprint so far. While the most massive galaxy (M104) has a significant higher abundance of dwarfs, NGC3521, NGC2903, and NGC2683 have a similar luminosity function as the Milky Way. These latter three galaxies also have a similar stellar mass and might be considered Milky Way analogs. UGCA127 is a low-mass galaxy but almost reaches the same number of dwarfs as the Milky Way at our limiting magnitude. We have searched for hints of lopsidedness in the satellite distributions, but found none to be significant. The next step will be to confirm these members through either distance or velocity measurements.

Spiral arms are a common feature of local galaxies, but the exact form of the distribution of mass and light in them is not well known. In this work, we aim to measure this distribution as accurately as possible, focusing on individual spiral arms and using the so-called slicing method. The sample consists of 19 well-resolved, viewed face-on spiral galaxies from the S$^4$G survey. We work primarily with infrared images at 3.6 $\mu$m from the same survey, and, secondarily, with ultraviolet data from the GALEX telescope. We derive the properties of the spiral arms step by step, starting from their overall shape, then measuring their brightness profile and width variation along the arm, and then examining the fine structure of the profile across the arm, namely its skewness and Sérsic index. We construct a 2D photometric function of the spiral arm that can be used in further decomposition studies, validate it and identify the most and least important parameters. Finally, we show how our results can be used to unravel the nature of the spiral arms, supporting the evidence that NGC 4535 has a density wave in its disc.

The population of giant planets on wide orbits around low-mass M dwarf stars is poorly understood, but the unprecedented sensitivity of JWST NIRCam coronagraphic imaging now provides direct access to planets significantly less massive than Jupiter beyond 10 AU around the closest, youngest M dwarfs. We present the design, observations, and results of JWST GTO Program 1184, a Cycle 1 NIRCam coronagraphic imaging survey of 9 very nearby and young low-mass stars at 3-5 micron wavelengths. In the F356W and F444W filters, we achieve survey median 5-sigma contrasts deeper than 10-5 at a separation of 1", corresponding to 0.20 MJup in F444W and 1.30 MJup in F356W at planet-star separations of 10 AU. Our results include 3-5 micron debris disk detections and the identification of many extended and point-like sources in the final post-processed images. In particular, we have identified two marginal point source candidates having fluxes and color limits consistent with model predictions for young sub-Jupiter mass exoplanets. Under the assumption that neither candidate is confirmed, we place the first direct-imaging occurrence constraints on M dwarf wide-orbit (semimajor axes 10-100 AU), sub-Jupiter mass exoplanets (0.3-1 MJup). We find frequency limits of < 0.10 and < 0.16 objects per star with 1 and 3-sigma confidence, respectively. This survey brings to the forefront the unprecedented capabilities of JWST NIRCam coronagraphic imaging when targeting young, low-mass stars and acts as a precursor to broader surveys to place deep statistical constraints on wide-orbit, sub-Jupiter mass planets around M dwarfs.

First-principle studies of radiative processes aimed at explaining the origin of type II and type III solar radio bursts raise questions on the implications of downshifted electron beam plasma excitations with frequency (slightly) below the plasma frequency ($\omega\lesssim\omega_{pe}$) in the generation of radio emissions. Unlike the beam-induced Langmuir waves ($\omega \gtrsim \omega_{pe}$) in the standard radio emission plasma model, the primary wave excitations of cooler and/or denser beams have predominantly downshifted frequencies. Broadbands of such downshifted excitations are also confirmed by in situ observations in association with terrestrial foreshock and electron beams (in contrast to narrowband Langmuir waves), but their involvement in radiative processes has not been examined so far. We revisit three radiative scenarios specific to downshifted primary excitations, and the results demonstrate their direct or indirect involvement in plasma radio emission. Downshifted excitations of an electron beam primarily play an indirect role, contributing to the relaxation to a plateau-on-tail still able to induce Langmuir beam waves that satisfy conditions for nonlinear wave-wave interactions leading to free radio waves. At longer time scales, the primary excitations can become predominantly downshifted, and then directly couple with the secondary (backscattered) Langmuir waves to generate the second harmonic of radio emissions. Two counterbeams are more efficient and lead to faster radiative mechanisms, involving counterpropagating downshifted excitations, which couple to each other and generate intense, broadband and isotropic radio spectra of downshifted second harmonics. Such a long-lasting (second) radio harmonic can thus be invoked to distinguish regimes with downshifted ($\omega \gtrsim \omega_{pe}$) primary excitations.

We present medium-wave ($\sim$0.5~$\mu$m to $\sim$13~$\mu$m) radiative flux distributions and spectra derived from high-resolution atmospheric dynamics simulations of an exoplanet \WASPP. This planet serves to illustrate several important features. Assuming different chemical compositions for its atmosphere (e.g., H$_2$/He only and $Z \in \{1, 12\}$ times solar metallicity), the outgoing radiative flux is computed using full radiative transfer that folds in the James Webb Space Telescope (JWST) and Ariel instrument characteristics. We find that the observed variability depends strongly on the the assumed chemistry and the instrument wavelength range, hence the probed altitude of the atmosphere. With H$_2$/He only, the flux and variability originate near the 10$^5$~Pa level; with solar and higher metallicity, $\sim$10$^3$~Pa level is probed, and the variability is distinguishably reduced. Our calculations show that JWST and Ariel have the sensitivity to capture the atmospheric variability of exoplanets like \WASPP, depending on the metallicity -- both in repeated eclipse and phase-curve observations.

The census of stellar streams and dwarf galaxies in the Milky Way provides direct constraints on galaxy formation models and the nature of dark matter. The DESI Milky Way survey (with a footprint of 14,000$~deg{^2}$ and a depth of $r<19$ mag) delivers the largest sample of distant metal-poor stars compared to previous optical fiber-fed spectroscopic surveys. This makes DESI an ideal survey to search for previously undetected streams and dwarf galaxies. We present a detailed characterization of the Cocytos stream, which was re-discovered using a clustering analysis with a catalog of giants in the DESI year 3 data, supplemented with Magellan/MagE spectroscopy. Our analysis reveals a relatively metal-rich ([Fe/H]$=-1.3$) and thick stream (width$=1.5^\circ$) at a heliocentric distance of $\approx 25$ kpc, with an internal velocity dispersion of 6.5-9 km s$^{-1}$. The stream's metallicity, radial orbit, and proximity to the Virgo stellar overdensities suggest that it is most likely a disrupted globular cluster that came in with the Gaia-Enceladus merger. We also confirm its association with the Pyxis globular cluster. Our result showcases the ability of wide-field spectroscopic surveys to kinematically discover faint disrupted dwarfs and clusters, enabling constraints on the dark matter distribution in the Milky Way.

We explore the effects of Bumblebee gravity on the propagation of ultra-high energy cosmic rays (UHECRs) using astrophysical sources modeled in the Unger-Farrar-Anchordoqui (UFA) framework (2015), which includes star formation rate (SFR), gamma-ray bursts (GRBs), and active galactic nuclei (AGN). We compute the density enhancement factor for various source separation distances ($d_\text{s}$s) up to 100 Mpc within the Bumblebee gravity scenario. Additionally, we calculate the CRs flux and their suppression, comparing the results with observational data from the Pierre Auger Observatory (PAO) and the Telescope Array through $\chi^2$ and $\chi_\text{red}^2$ analysis for the flux and Levenberg-Marquardt algorithm for suppression. The anisotropy in CRs arrival directions is examined, with corresponding $\chi^2$ and $\chi_\text{red}^2$ values obtained from the PAO surface detector data (SD 750 and SD 1500). Finally, we present skymaps of flux and anisotropy under different model assumptions, providing insights into the observational signatures of UHECRs in Bumblebee gravity. Our results show that increasing the Bumblebee gravity parameter $l$ enhances the density factor $\xi$, particularly at low energies, highlighting Lorentz violation's impact on CRs' propagation. Larger $d_\text{s}$ values amplify deviations from the $\Lambda$CDM model, with AGN sources dominating at high energies and GRB/SFR sources at lower energies. The skymaps indicate the structured flux patterns at large $d_\text{s}$ and structured anisotropy at higher energies.

The initial Lorentz factor ($\Gamma_{\text{0}}$) plays a crucial role in uncovering the physical characteristics of gamma-ray bursts (GRBs). Previous studies have indicated that the ambient medium density index $k$ for GRBs falls in the range of 0 - 2, rather than exactly equal to 0 (homogeneous interstellar ambient) or 2 (typical stellar wind). In this work, we aim to constrain the $\Gamma_0$ of GRBs considering their distinct circumburst medium. We select a total of 33 GRBs for our analysis, comprising 7 X-ray GRBs and 26 optical GRBs. Subsequently, by utilizing the deceleration time of fireball $t_{\rm p}$, we derive the $\Gamma_0$ for the 33 GRBs assuming the radiation efficiency of $\eta =$ 0.2. The inferred initial Lorentz factor was found to be from 50 to 500, consistent with previous studies. We then investigate the correlation between the $\Gamma_0$ and the isotropic energy $E_{\rm \gamma,iso}$ (as well as the mean isotropic luminosity $L_{\rm \gamma,iso}$), finding very tight correlations between them, i.e., $\Gamma_0$ $\propto$ $E^{0.24}_{\rm \gamma,iso,52}$ ($\Gamma_0$ $\propto$ $L^{0.20}_{\rm \gamma,iso.49}$) with $\eta$=0.2. Additionally, we verify the correlation among $\Gamma_0$, the isotropic energy $E_{\rm \gamma,iso}$ (or $L_{\rm \gamma,iso}$) and the peak energy $E_{\rm{p,z}}$, i.e., $E_{\rm \gamma,iso,52}$ $\propto$ $\Gamma^{1.36}_0$$E^{0.82}_{\rm{p,z}}$ ($L_{\rm \gamma,iso,49}$ $\propto$ $\Gamma^{1.05}_0$$E^{0.66}_{\rm{p,z}}$) under the same radiation efficiency ($\eta$=0.2).

We present a new radio continuum study of the Large Magellanic Cloud supernova remnant (SNR) MC SNR J0519-6902. With a diameter of ~8 pc, this SNR shows a radio ring-like morphology with three bright regions toward the north, east, and south. Its linear polarisation is prominent with average values of 5 +- 1% and 6 +- 1% at 5500 and 9000 MHz, and we find a spectral index of -0.62 +- 0.02 , typical of a young SNR. The average rotation measure is estimated at -124 +- 83 rad m-2 and the magnetic field strength at ~11 muG. We also estimate an equipartition magnetic field of 72 +- 5 muG and minimum explosion energy of Emin = 2.6x1048 erg. Finally, we identified an H I cloud that may be associated with MC SNR J0519-6902, located in the southeastern part of the remnant, along with a potential wind-bubble cavity.

The formation and origin of Jets from Z sources are not well understood, although an X-ray-radio correlation has been observed. We analyzed a few observations of Sco X-1 using the Rossi X-ray Timing Experiment Satellite. Out of the 17 observations, 5 showed lags of a few 10s of seconds with an asymmetry in the CCF between the soft and hard bands in their cross-correlation function (CCF) analysis. Interestingly, during these observations, a ballistic-type radio jet of Ultra-relativistic(UR) nature was reported. The observed lags and associated cross-correlation coefficients were validated using simulations. The rest of the 12 observations' CCFs were symmetric, and their associated Power Density Spectrum (PDS) displayed Normal Branch(NBO)/Normal + Horizontal Branch Oscillations(NBO+HBO). The X-ray spectral study of 2 obs. where radio core emission was seen with abrupt variation in both PDS and CCF showed a black-body flux variation of 10-20%, but no spectral parameter varied. We suggest that the ballistic jet caused a disturbance in the inner accretion region, viz., the Boundary Layer plausibly along with the Corona, that caused the lags observed in the CCFs along with the absence of any oscillatory features in the PDS tracing only a flat-topped noise. Whereas the regions with no lags showed a persistent NBO/NBO+HBO feature, suggesting a steady accretion flow. Although the UR jet can't be related to NBO or HBO, we suggest it could be related to the phenomena that cause NBO since the majority of PDSs displayed NBO. We also constrain the inner accretion region size to 20-30 km, which is responsible for the accretion ejecta in Sco X-1.

Star formation is a series of mass assembly processes and starless cores, those cold and dense condensations in molecular clouds, play a pivotal role as initial seeds of stars. With only a limited sample of known starless cores, however, the origin and growth of such stellar precursors had not been well characterized previously. Meanwhile, the recent discovery of CH$_3$OH emission, which is generally associated with desorbed icy mantle in warm regions, particularly at the periphery of starless cores also remains puzzling. We present sensitive ALMA (Band~3) observations (at 3~mm) toward a sample of newly identified starless cores in the Orion Molecular Cloud. The spatially resolved images distinctly indicate that the observed CH$_3$OH and N$_2$H$^+$ emission associated with these cores are morphologically anti-correlated and kinematically offset from each other. We postulate that the CH$_3$OH emission highlights the desorption of icy mantle by shocks resulting from gas piling onto dense cores in the filaments traced by N$_2$H$^+$. Our magnetohydrodynamic (MHD) simulations of star formation in turbulent clouds combined with radiative transfer calculations and imaging simulations successfully reproduced the observed signatures and reaffirmed the above scenario at work. Our result serves as an intriguing and exemplary illustration, a snapshot in time, of the dynamic star-forming processes in turbulent clouds. The results offer compelling insights into the mechanisms governing the growth of starless cores and the presence of gas-phase complex organic molecules associated with these cores.

We characterise the rest-frame 1500 Å UV luminosity Function (UVLF) from deep AstroSat/UVIT F154W and N242W imaging in the Great Observatories Origins Survey South (GOODS-S) deep field. The UVLFs are constructed and subsequently characterised with fitted Schechter function parameters from FUV observations at z$<0.13$ and NUV observations in seven redshift bins in z~0.8-0.4. The UVLF slope ($\alpha$) and characteristic magnitude ($M^*$) are consistent with previous determinations for this redshift range based on AstroSat/UVIT GOODS-North observations, as well as with those from Galaxy evolution Explorer and Hubble Space Telescope observations. However, differences in the normalisation factor ($\phi_{*}$) are present for UVLFs for some redshift bins. We compute the UV luminosity density, $\rho_{\rm UV}$, combining our determined UVLF parameters with literature determinations out to z$\sim10$. The $\rho_{\rm UV}$ trend with redshift implies the rapid increase in cosmic star formation till its peak at z$\sim3$ (cosmic noon) followed by a slow decline till present day. Both the initial increase in cosmic star formation and subsequent decline are found to be more rapid than previous determinations.

We present two approaches for "painting" baryonic properties relevant to the Sunyaev-Zel'dovich (SZ) effect - optical depth and Compton-$y$ - onto 3-dimensional $N$-body simulations, using the MillenniumTNG suite as a benchmark. The goal of these methods is to produce fast and accurate reconstruction methods to aid future analyses of baryonic feedback using the SZ effect. The first approach employs a Gaussian Process emulator to model the SZ quantities via a transfer function, while the second utilizes Hybrid Effective Field Theory (HEFT) to reproduce these quantities within the simulation. Our analysis involves comparing both methods to the true MillenniumTNG optical depth and Compton-$y$ fields using several metrics, including the cross-correlation coefficient, power spectrum, and power spectrum error. Additionally, we assess how well the reconstructed fields correlate with dark matter haloes across various mass thresholds. The results indicate that the transfer function method yields more accurate reconstructions for fields with initially high correlations ($r \approx 1$), such as between the optical depth and dark matter fields. Conversely, the HEFT-based approach proves more effective in enhancing correlations for fields with weaker initial correlations ($r \sim 0.5$), such as between the Compton-$y$ and dark matter fields. Lastly, we discuss extensions of our methods to improve the reconstruction performance at the field level.

Previous studies, based on precise modeling of a gravitationally lensing image, have identified what may be a extremely compact, dark perturber in the well-known lensing system SDSSJ0946+1006 (the "Jackpot"). Its remarkable compactness challenges the standard cold dark matter (CDM) paradigm. In this paper, we explore whether such a compact perturber could be explained as a core-collapsed halo described by the self-interacting dark matter (SIDM) model. Using the isothermal Jeans method, we compute the density profiles of core-collapsed halos across a range of masses. Our comparison with observations indicates that only a core-collapsed halo with a total mass of approximately $10^{11}~{\rm M_{\odot}}$ could produce an inner density profile and mass enclosed within 1 kpc that is consistent with observational data. However, such a massive dark matter halo should host a galaxy detectable by prior Hubble imaging, which is not observed. Thus, the core-collapsed SIDM halo model struggles to fully account for the exotic nature of the "little dark dot" in the "Jackpot" lens.

Component separation is the process of extracting one or more emission sources in astrophysical maps. It is therefore crucial to develop models that can accurately clean the cosmic microwave background (CMB) in current and future experiments. In this work, we present a new methodology based on neural networks which operates on realistic temperature and polarization simulations. We assess its performance by comparing the power spectra of the output maps with those of the input maps and other emissions. For temperature, we obtain residuals of $20 \pm \mu K^{2}$. For polarization, we analyze the $E$ and $B$ modes, which are related to density (scalar) and primordial gravitational waves (tensorial) perturbations occurring in the first second of the Universe, obtaining residuals of $10^{-2} \mu K^{2}$ at $l>200$ and $10^{-2}$ and $10^{-3} \mu K^{2}$ for $E$ and $B$, respectively.

Context. Tracing wave activity from the photosphere to the corona has important implications for coronal heating and prediction of the solar wind. Despite extensive theory and simulations, the detection of waves in realistic MHD simulations still presents a large challenge due to wave interaction, mode conversion, and damping mechanisms. Aims. We conducted this study to detect localised wave activity within a realistic MHD simulation of the solar atmosphere by the Bifrost code. Methods. We present a new method of detecting the most significant contributions of wave activity within localised areas of the domain, aided by Discrete Fourier Transforms and frequency filtering. We correlate oscillations in the vertical & horizontal magnetic field, velocities parallel & perpendicular to the magnetic field, and pressure to infer the nature of the dominant wave modes. Results. Our method captures the most powerful frequencies and wavenumbers, as well as providing a new diagnostic for damping processes. We infer the presence of magnetoacoustic waves in the boundaries of prominent chromospheric/coronal swirling features. We find these waves are likely damped by viscous heating in the swirl boundaries, contributing to heating in the upper atmosphere. Conclusions. Using the most significant frequencies decomposition, we highlight that energy can be transported from the lower atmosphere to the upper atmosphere through waves and fluctuations along the swirl boundaries. Although further analysis is needed to confirm these findings, our new method provides a path forward to investigate wave activity in the solar atmosphere

The combination of fluorescence and surface detectors at the Pierre Auger Observatory offers unprecedented precision in testing models of hadronic interactions at center-of-mass energies around 70 TeV and beyond. However, for some time, discrepancies between model predictions and measured air-shower data have complicated efforts to accurately determine the mass composition of ultra-high-energy cosmic rays. A key inconsistency is the deficit of simulated signals compared to those measured with the surface detectors, typically interpreted as a deficit in the muon signal generated by the hadronic component of simulated showers. Recently, a new global method has been applied to the combined data from the surface and fluorescence detectors at the Pierre Auger Observatory. This method simultaneously determines the mass composition of cosmic rays and evaluates variations in the simulated depth of the shower maximum and hadronic signals on the ground. The findings reveal not only the alleviated muon problem but also show that all current models of hadronic interactions predict depths of the shower maximum that are too shallow, offering new insights into deficiencies in these models from a broader perspective.

Recent high-resolution observations have established a strong link between black hole jets and accretion disk structures, particularly in the 3.5 mm wavelength band [Nature. 616, 686 (2023)]. In this work, we propose a ``jet-modified Novikov-Thorne disk model'' that explicitly incorporates jet luminosity into the accretion disk radiation framework. By integrating synchrotron radiation from relativistic electrons in the jet, we derive a modified luminosity function that accounts for both the accretion disk and jet contributions. Our analysis demonstrates that the inclusion of jet luminosity enhances the total accretion disk luminosity by approximately 33.5\%, as derived from the integration of radiative flux. Furthermore, we compare our modified model with the standard Novikov-Thorne model and find that the jet contribution remains significant across different observational inclinations. These results highlight the necessity of incorporating jet effects when estimating the observable flux of black hole accretion systems, which has direct implications for future astronomical observations.

We present a novel pipeline that uses a convolutional neural network (CNN) to improve the detection capability of near-Earth asteroids (NEAs) in the context of planetary defense. Our work aims to minimize the dependency on human intervention of the current approach adopted by the Zwicky Transient Facility (ZTF). The target NEAs have a high proper motion of up to tens of degrees per day and thus appear as streaks of light in the images. We trained our CNNs to detect these streaks using three datasets: a set with real asteroid streaks, a set with synthetic (i.e., simulated) streaks and a mixed set, and tested the resultant models on real survey images. The results achieved were almost identical across the three models: $0.843\pm0.005$ in completeness and $0.820\pm0.025$ in precision. The bias on streak measurements reported by the CNNs was $1.84\pm0.03$ pixels in streak position, $0.817\pm0.026$ degrees in streak angle and $-0.048\pm0.003$ in fractional bias in streak length (computed as the absolute length bias over the streak length, with the negative sign indicating an underestimation). We compared the performance of our CNN trained with a mix of synthetic and real streaks to that of the ZTF human scanners by analyzing a set of 317 streaks flagged as valid by the scanners. Our pipeline detected $80~\%$ of the streaks found by the scanners and 697 additional streaks that were subsequently verified by the scanners to be valid streaks. These results suggest that our automated pipeline can complement the work of the human scanners at no cost for the precision and find more objects than the current approach. They also prove that the synthetic streaks were realistic enough to be used for augmenting training sets when insufficient real streaks are available or exploring the simulation of streaks with unusual characteristics that have not yet been detected.

In this article we extend a study of the validity conditions of the separate-universe approach of cosmological perturbations to models of inflation with multiple fields. The separate-universe approach consists in describing the universe as a collection of homogeneous and isotropic patches, giving us an effective description of perturbation theory at large scales through phase-space reduction. This approximation is a necessary step in stochastic inflation, an effective theory of coarse-grained, super-Hubble, scalar fields fluctuations. One needs a stochastic inflation description in the context of primordial black hole productions since it needs enhancements of the curvature power spectrum. It easily achievable in multifield inflation models but necessarily comes with strong diffusive effects. We study and compare cosmological perturbation theory and the separate-universe approach in said non-linear sigma models as a typical framework of multifield inflation and employing the Hamiltonian formalism to keep track of the complete phase space (or the reduced isotropic phase space in the separate-universe approach). We find that the separate-universe approach adequately describes the cosmological perturbation theory provided the wavelength of the modes considered is greater that several lower bounds that depend on the cosmological horizon and the inverse of the effective Hamiltonian masses of the fields; the latter being fixed by the coupling potential and the field-space geometry. We also compare gauge-invariant variables and several gauge fixing procedures in both approaches. For instance, we showed that the uniform-expansion gauge is nicely described by the separate-universe picture, hence qualifying its use in stochastic inflation as commonly done.

Relativistic jets from supermassive black holes in active galactic nuclei are amongst the most powerful phenomena in the universe, acting to regulate the growth of massive galaxies. Similar jets from stellar-mass black holes offer a chance to study the same phenomena on accessible observation time scales. However, such comparative studies across black hole masses and time scales remain hampered by the long-standing perception that stellar-mass black hole jets are in a less relativistic regime. We used radio interferometry observations to monitor the Galactic black hole X-ray binary 4U 1543-47 and discovered two distinct, relativistic ejections launched during a single outburst. Our measurements reveal a likely Lorentz factor of $\sim$ 8 and a minimum of 4.6 at launch with 95% confidence, demonstrating that stellar-mass black holes in X-ray binaries can launch jets as relativistic as those seen in active galactic nuclei.

A pressureless dark matter component fits well with several cosmological observations. However, there are indications that cold dark matter may encounter challenges in explaining observations at small scales, particularly at galactic scales. Observational data suggest that dark matter models incorporating a pressure component could provide solutions to these small-scale problems. In this work, we investigate the possibility that present-day dark matter may result from a decaying non-cold dark matter sector transitioning into the dark energy sector. As the sensitivity of astronomical surveys rapidly increases, we explore an interacting scenario between dark energy and non-cold dark matter, where dark energy has a constant equation of state ($w_{\rm de}$), and dark matter, being non-cold, also has a constant (non-zero) equation of state ($w_{\rm dm}$). Considering the phantom and quintessence nature of dark energy, characterized by its equation of state, we separately analyze interacting phantom and interacting quintessence scenarios. We constrain these scenarios using Cosmic Microwave Background (CMB) measurements and their combination with external probes, such as DESI-BAO and PantheonPlus. From our analyses, we find that a very mild preference for non-cold dark matter cannot be excluded based on the employed datasets. Additionally, for some datasets, there is a pronounced preference for the presence of an interaction at more than 95\% confidence level (CL). Moreover, when the dark energy equation of state lies in the phantom regime, the $S_8$ tension can be alleviated. This study suggests that cosmological models incorporating a non-cold dark matter component should be considered as viable scenarios with novel phenomenological implications, as reflected in the present work.

The mass composition of ultra-high-energy cosmic rays is an open problem in astroparticle physics. It is usually inferred from the depth of the shower maximum (Xmax) of cosmic-ray showers, which is only ambiguously determined by modern hadronic interaction models. We examine a data-driven scenario, in which we consider the expectation value of Xmax as a free parameter. We test the novel hypothesis whether the cosmic-ray data from the Pierre Auger Observatory can be interpreted in a consistent picture, under the assumption that the mass composition of cosmic rays at the highest energies is dominated by high metallicity, resulting in pure iron nuclei at energies above ~40 EeV. We investigate the implications on astrophysical observations and hadronic interactions, and we discuss the global consistency of the data assuming this heavy-metal scenario. We conclude that the data from the Pierre Auger Observatory can be interpreted consistently if the expectation values for Xmax from modern hadronic interaction models are shifted to larger values.

Energy limits that delineate the `habitable zone' for exoplanets depend on a given exoplanet's net planetary albedo (or `Bond albedo'). We here demonstrate that the planetary albedo of an observed exoplanet is limited by the above-cloud atmosphere - the region of the atmosphere that is probed in remote observation. We derive an analytic model to explore how the maximum planetary albedo depends on the above-cloud optical depth and scattering versus absorbing properties, even in the limit of a perfectly reflective grey cloud layer. We apply this framework to sub-Neptune K2-18b, for which a high planetary albedo has recently been invoked to argue for the possibility of maintaining a liquid water ocean surface, despite K2-18b receiving an energy flux from its host star that places it inside of its estimated `habitable zone' inner edge. We use a numerical multiple-scattering line-by-line radiative transfer model to retrieve the albedo of K2-18b based on the observational constraints from the above-cloud atmosphere. Our results demonstrate that K2-18b's observed transmission spectrum already restricts its possible planetary albedo to values below the threshold required to be potentially habitable, with the data favouring a median planetary albedo of 0.17-0.18. Our results thus reveal that currently characteriseable sub-Neptunes are likely to be magma-ocean or gas-dwarf worlds. The methods that we present are generally applicable to constrain the planetary albedo of any exoplanet with measurements of its observable atmosphere, enabling the quantification of potential exoplanet habitability with current observational capabilities.

We provide a systematic study of the Starobinsky-Higgs inflation model in the presence of an additional cubic term of the Ricci scalar. We investigate, in particular, the effects of the cubic term on the spectral index $n_s$ and the tensor-to-scalar ratio $r$. Through both analytical and numerical analyses, we show that the $R^3$-corrected Starobinsky-Higgs model can achieve compatibility with cosmic microwave background observations while producing distinct observational signatures with different frequency ranges. In addition, we discuss the complementarity between different observational probes, including the scalar-induced gravitational waves and spectral distortions, offering an independent probe of the enhanced curvature perturbations. Detection prospects are also discussed.

Planets are a natural byproduct of the stellar formation process, resulting from local aggregations of material within the disks surrounding young stars. Whereas signatures of gas-giant planets at large orbital separations have been observed and successfully modeled within protoplanetary disks, the formation pathways of planets within their host star's future habitable zones remain poorly understood. Analyzing multiple nights of observations conducted over a short, two-month span with the MIRC-X and PIONIER instruments at the CHARA Array and VLTI, respectively, we uncover a highly active environment at the inner-edge of the planet formation region in the disk of HD 163296. In particular, we localize and track the motion of a disk feature near the dust-sublimation radius with a pattern speed of less than half the local Keplerian velocity, providing a potential glimpse at the planet formation process in action within the inner astronomical unit. We emphasize that this result is at the edge of what is currently possible with available optical interferometric techniques and behooves confirmation with a temporally dense followup observing campaign.

It is established that there exists a direct link between the formation history of star cluster populations and their host galaxies, however, our lacking understanding of star cluster assembly prohibits us to make full use of their ability to trace galaxy evolution. In this work we introduce a new variation of the 2020 version of the semi-analytical galaxy formation model "L-Galaxies" that includes the formation of star clusters above 10^4 M_Sun and probes different physical assumptions that affect their evolution over cosmic time. We use properties of different galaxy components and localised star formation to determine the bound fraction of star formation in disks. After randomly sampling masses from an environmentally-dependent star cluster initial mass function, we assign to each object a half-mass radius, metallicity, and distance from the galaxy centre. We consider up to 2000 individual star clusters per galaxy and evolve their properties over time taking into account stellar evolution, two-body relaxation, tidal shocks, dynamical friction, and a re-positioning during galaxy mergers. Our simulation successfully reproduces several observational quantities, such as the empirical relationship between the absolute V -band magnitude of the brightest young star clusters and the host galaxy star formation rate, the mass function of young star clusters, or mean metallicities of the star cluster distributions versus galaxy masses. The simulation reveals great complexity in the z = 0 star cluster population resulting from differential destruction channels and origins, including in-situ populations in the disk, a major merger-induced heated component in the halo, and accreted star clusters. Model variations point out the importance of e.g. the shape of the star cluster initial mass function or the relationship between the sound speed of cold gas and the star formation rate.

29P/Schwassmann-Wachmann 1 (SW1) is both the first-discovered active Centaur and the most outburst-prone comet known. The nature of SW1's many outbursts, which regularly brighten the comet by five magnitudes or more, and what processes power them has been of particular interest since SW1's discovery in the 1920s. In this paper, we present and model four epochs of low-resolution near-infrared spectroscopy of SW1 taken with the NASA Infrared Telescope Facility and Lowell Discovery Telescope between 2017 and 2022. This dataset includes one large outburst, two periods of low activity ("quiescence" or "quiescent activity"), and one mid-sized outburst a few days after one of the quiescent observations. The two quiescent epochs appear similar in both spectral slope and modeled grain size distributions, but the two outbursts are significantly different. We propose that the two can be reconciled if smaller dust grains are accelerated more than larger ones, such that observations closer to the onset of an outburst are more sensitive to the finer-grained dust on the outside of the expanding cloud of material. These outbursts can thus appear very rapid but there is still a period in which the dust and gas are well-coupled. We find no strong evidence of water ice absorption in any of our spectra, suggesting that the areal abundance of ice-dominated grains is less than one percent. We conclude with a discussion of future modeling and monitoring efforts which might be able to further advance our understanding of this object's complicated activity patterns.

Primordial black holes (PBHs) can catalyze first-order phase transitions (FOPTs) in their vicinity, potentially modifying the gravitational wave (GW) signals from PTs. In this study, we present the first comprehensive analysis of this catalytic effect during supercooled PTs within the high PBH number density regime. Applying the analytical model with envelope approximation, we derive the general expressions of GW spectrum in the presence of PBHs. We find that at relatively small PBH number densities, the GW signals are amplified due to the large-size bubbles. While higher PBH number densities suppress GW signals, since the accelerated PT progresses too rapidly. We further extend our findings to the bulk flow model and to scalar-induced GWs (SIGWs) generated during PTs. By conducting data fitting with the NANOGrav 15-year dataset, we find that the PBH catalytic effect significantly alters the estimation of PT parameters. Notably, our analysis of the bubble collision GWs reveals that, the asteroid-mass PBHs ($10^{-16} - 10^{-12} M_\odot$) as the whole dark matter is incompatible with the PT interpretation of pulsar timing array signals. However, incorporating SIGWs can reduce this incompatibility for PBHs in the mass range $10^{-14} - 10^{-12} M_\odot$.

The connection between the atmospheric composition of giant planets and their origin remains elusive. In this study, we explore how convective mixing can link the planetary primordial state to its atmospheric composition. We simulate the long-term evolution of gas giants with masses between 0.3 and 3 Jupiter masses, considering various composition profiles and primordial entropies (assuming no entropy-mass dependence). Our results show that when convective mixing is considered, the atmospheric metallicity increases with time and that this time evolution encodes information about the planetary primordial structure. Additionally, the degree of compositional mixing affects the planetary radius, altering its evolution in a measurable way. By applying mock observations, we demonstrate that combining radius and atmospheric composition can help to constrain the planetary formation history. Young systems emerge as prime targets for such characterization, with lower-mass gas giants (approaching Saturn's mass) being particularly susceptible to mixing-induced changes. Our findings highlight convective mixing as a key mechanism for probing the primordial state of giant planets, offering new constraints on formation models and demonstrating that the conditions inside giant planets shortly after their formation are not necessarily erased over billions of years and can leave a lasting imprint on their evolution.

According to the giant impact theory, the Moon formed by accreting the circum-terrestrial debris disk produced by Theia colliding with the proto-Earth. The giant impact theory can explain most of the properties of the Earth-Moon system, however, simulations of giant impact between a planetary embryo and the growing proto-Earth indicate that the materials in the circum-terrestrial debris disk produced by the impact originate mainly from the impactor, contradicting with the fact that different Solar System bodies have distinct compositions. Thus, the giant impact theory has difficulty explaining the Moon's Earth-like isotopic compositions. More materials from the proto-Earth could be delivered to the circum-terrestrial debris disk when a slightly sub-Mars-sized body collides with a fast rotating planet of rigid rotation but the resulting angular momentum is too large compared with that of the current Earth-Moon system. Since planetesimals accreted by the proto-Earth hit the surface of the proto-Earth, enhancing the rotation rate of the surface of the proto-Earth. The surface's fast rotation rate relative to the slow rotation rate of the inner region of the proto-Earth leads to transfer of angular momentum from surface to inner, resulting in the differential rotation. Here, we show that the giant impact of a sub-Mars-sized body on a differential rotating proto-Earth with a fast rotating outer region and a relative slow rotating inner region could result in a circum-terrestrial debris disk with materials predominately from the proto-Earth without violating the angular momentum constraint. The theory proposed here may provide a viable way of explaining the similarity in the isotopic compositions of the Earth and Moon.

Observations have established that coherent radio emission from pulsars arise at few hundred kilometers above stellar surface. Recent polarization studies have further demonstrated that plasma instabilities are necessary for charge bunching that gives rise to coherent emission. The formation of charged solitons in the electron-positron plasma is the only known bunching mechanism that can be realised at these heights. More than five decades of observations have revealed a number of emission features that should emerge from any valid radio emission mechanism. We have carried out numerical calculations to find the features of average emission from curvature radiation due to charged solitons. The characteristic curvature radiation spectrum has been updated from the well known one-dimensional dependence into a general two-dimensional form, and contribution from each soliton along observer's line of sight (LOS) has been added to reproduce the pulsar emission. The outflowing plasma is formed by sparking discharges above the stellar surface that are located within concentric rings resembling the core-cone emission beam, and uniform distribution of solitons along any LOS has been assumed. The observed effects of radius to frequency mapping, where the lower frequency emission originates from higher altitudes, is seen in this setup. The power law spectrum and relative steepening of the core spectra with respect to the cones also emerges. The estimated polarization position angle reflects the geometrical configuration of pulsars as expected. These studies demonstrate the efficacy of coherent curvature radiation from charged solitons to reproduce the average observational features of pulsars.

The study of the gravitational wave signatures of neutron star oscillations may provide important information of their interior structure and Equation of State (EoS) at high densities. We present a novel technique based on physically informed neural networks (PINNs) to solve the eigenvalue problem associated with normal oscillation modes of neutron stars. The procedure is tested in a simplified scenario, with an analytical solution, that can be used to test the performance and the accuracy of the method. We show that it is possible to get accurate results of both the eigenfrequencies and the eigenfunctions with this scheme. The flexibility of the method and its capability of adapting to complex scenarios may serve in the future as a path to include more physics into these systems.

One notable example of exoplanet diversity is the population of circumbinary planets, which orbit around both stars of a binary star system. There are so far only 16 known circumbinary exoplanets, all of which lie in the same orbital plane as the host binary. Suggestions exist that circumbinary planets could also exist on orbits highly inclined to the binary, close to 90$^{\circ}$, polar orbits. No such planets have been found yet but polar circumbinary gas and debris discs have been observed and if these were to form planets then those would be left on a polar orbit. We report strong evidence for a polar circumbinary exoplanet, which orbits a close pair of brown dwarfs which are on an eccentric orbit. We use radial-velocities to measure a retrograde apsidal precession for the binary, and show that this can only be attributed to the presence of a polar planet.

Recent three-dimensional magnetohydrodynamical simulations of the common-envelope interaction revealed the self-consistent formation of bipolar magnetically driven outflows launched from a toroidal structure resembling a circumbinary disk. So far, the dynamical impact of bipolar outflows on the common-envelope phase remains uncertain and we aim to quantify its importance. We illustrate the impact on common-envelope evolution by comparing two simulations -- one with magnetic fields and one without -- using the three-dimensional moving-mesh hydrodynamics code AREPO. We focus on the specific case of a $10 M_\odot$ red supergiant star with a $5 M_\odot$ black hole companion. By the end of the magnetohydrodynamic simulations (after $\sim 1220$ orbits of the core binary system), about $6.4 \%$ of the envelope mass is ejected via the bipolar outflow, contributing to angular momentum extraction from the disk structure and core binary. The resulting enhanced torques reduce the final orbital separation by about $24 \%$ compared to the hydrodynamical scenario, while the overall envelope ejection remains dominated by recombination-driven equatorial winds. We analyze field amplification and outflow launching mechanisms, confirming consistency with earlier studies: magnetic fields are amplified by shear flows, and outflows are launched by a magneto-centrifugal process, supported by local shocks and magnetic pressure gradients. These outflows originate from $\sim 1.1$ times the orbital separation. We conclude that the magnetically driven outflows and their role in the dynamical interaction are a universal aspect, and we further propose an adaptation of the $\alpha_\mathrm{CE}$-formalism by adjusting the final orbital energy with a factor of $1+ M_\mathrm{out}/\mu$, where $M_\mathrm{out}$ is the mass ejected through the outflows and $\mu$ the reduced mass of the core binary. (abridged)

Observations of several gamma-ray bursts (GRBs) that are temporally and spatially compatible with energetic supernovae (hypernovae) has established their common origin. In one case (GRB 111209A/SN 2011kl) the associated supernova was classified as superluminous (SN 2011kl). The exceptional duration of the observed gamma-ray prompt emission of GRB 111209A (about 7 hours) is widely considered key to unlocking the physics behind the still mysterious origin of superluminous supernovae (SLSNe). We review the main observational and theoretical findings that may link some ultra-long GRBs to SLSNe. Specifically, we examine notable events, the role of progenitors and host galaxies in shaping these phenomena, and focus on the proposed models. While a magnetar central engine is a plausible mechanism for both luminous and long-duration GRBs, a conclusive answer remains elusive, as alternative explanations are still viable. Further observational and theoretical work is required to clarify progenitor pathways and explosion mechanisms, potentially extending the classical GRB-SN connection to rare superluminous hypernovae.

We present a narrowband imaging on a spectroscopically confirmed protocluster ``D4UD01'' at z=3.24 using CFHT/WIRCam. We identify a sample of 24 [O III] emission line galaxies in the field, which forms a large overdensity in the protocluster region. The protocluster is expected to evolve into a Virgo-like cluster by z=0. Utilizing multiwavelength data, we derive the physical properties of these [O III] emitters and find they are medium mass normal star-forming galaxies ($\sim10^{10}$M$_\odot$) roughly following the star-forming main sequence. The [O III] emitters trace an overdensity spatially offset from that of photometric-redshift and quiescent galaxies, suggesting these distinct galaxy populations may inhabit dark matter halos that formed at different epochs. A comparative analysis of [O III] emitter properties shows similar characteristics in both protocluster and field environments. This protocluster likely represents an evolved structure that has progressed beyond its peak star-formation phase, although our limited sample size may prevent detection of subtle environmental effects.

We investigate the impact of chemical equilibration and the resulting bulk viscosity on non-radial oscillation modes of warm neutron stars at temperatures up to T~5 MeV, relevant for protoneutron stars and neutron-star post-merger remnants. In this regime, the relaxation rate of weak interactions becomes comparable to the characteristic frequencies of composition g-modes in the core, resulting in resonant damping. To capture this effect, we introduce the dynamic sound speed, a complex, frequency-dependent generalization of the adiabatic sound speed that encodes both the restoring force and the dissipative effects of bulk compression. Using realistic weak reaction rates and three representative equations of state, we compute the complex frequencies of composition g-modes with finite-temperature profiles. We find that bulk viscous damping becomes increasingly significant with temperature and can completely suppress composition g-modes. In contrast, the f-mode remains largely unaffected by bulk viscosity due to its nearly divergence-free character. Our results highlight the sensitivity of g-mode behavior to thermal structure, weak reaction rates, and the equation of state, and establish the dynamic sound speed as a valuable descriptor characterizing oscillation properties in dissipative neutron star matter.

We present the discovery of two quadruple star systems -- TIC 285853156 and TIC 392229331 -- each consisting of two bound eclipsing binary stars. Among the most compact quadruples known, TIC 392229331 and TIC 285853156 have the second and third shortest outer orbital periods (145 days and 152 days, respectively) after BU Canis Minoris (122 days, Pribulla et al. 2023). We demonstrate that both systems are long-term dynamically stable despite substantial outer orbital eccentricities (0.33 for TIC 285853156 and 0.56 for TIC 392229331). We previously reported these systems in Kostov et al. (2022) and Kostov et al. (2024) as 2+2 hierarchical quadruple candidates producing two sets of primary and secondary eclipses in TESS data, as well as prominent eclipse timing variations on both binary components. We combine all available TESS data and new spectroscopic observations into a comprehensive photodynamical model, proving that the component binary stars are gravitationally bound in both systems and finding accurate stellar and orbital parameters for both systems, including very precise determinations of the outer periods. TIC 285853156 and TIC 392229331 represent the latest addition to the small population of well-characterized proven quadruple systems dynamically interacting on detectable timescales.

GW170817 is the first binary neutron star merger detected with gravitational and electromagnetic waves, and its afterglow is still detectable 7 years post-merger. Some previous studies of the X-ray afterglow have claimed the onset of a new afterglow component or raised concerns about the data processing techniques. Motivated thus, we present here a reanalysis of X-ray afterglow data for GW170817 and find potential sources of discrepancies between the data reduction techniques employed by various research groups. We also analyze the updated panchromatic afterglow data to find that there is no significant evidence for any new afterglow component (e.g. due to the ejecta that gave rise to the kilonova) and that the jet must be still in a mildly relativistic phase. The decline in the afterglow light curve is significantly shallower compared to that expected from the standard synchrotron afterglow jet models with sideways spreading, indicating either an additional energy injection at late times or the velocity dependence on the microphysics parameters. In this context, we discuss the implications of the late time afterglow data on jet dynamics.

The sub-Neptune frontier has opened a new window into the rich diversity of planetary environments beyond the solar system. The possibility of hycean worlds, with planet-wide oceans and H$_2$-rich atmospheres, significantly expands and accelerates the search for habitable environments elsewhere. Recent JWST transmission spectroscopy of the candidate hycean world K2-18 b in the near-infrared led to the first detections of carbon-bearing molecules CH$_4$ and CO$_2$ in its atmosphere, with a composition consistent with predictions for hycean conditions. The observations also provided a tentative hint of dimethyl sulfide (DMS), a possible biosignature gas, but the inference was of low statistical significance. We report a mid-infrared transmission spectrum of K2-18 b obtained using the JWST MIRI LRS instrument in the ~6-12 $\mu$m range. The spectrum shows distinct features and is inconsistent with a featureless spectrum at 3.4-$\sigma$ significance compared to our canonical model. We find that the spectrum cannot be explained by most molecules predicted for K2-18 b with the exception of DMS and dimethyl disulfide (DMDS), also a potential biosignature gas. We report new independent evidence for DMS and/or DMDS in the atmosphere at 3-$\sigma$ significance, with high abundance ($\gtrsim$10 ppmv) of at least one of the two molecules. More observations are needed to increase the robustness of the findings and resolve the degeneracy between DMS and DMDS. The results also highlight the need for additional experimental and theoretical work to determine accurate cross sections of important biosignature gases and identify potential abiotic sources. We discuss the implications of the present findings for the possibility of biological activity on K2-18 b.

Ultralight particles, with a mass below the electronvolt scale, exhibit wave-like behavior and have arisen as a compelling dark matter candidate. A particularly intriguing subclass is scalar dark matter, which induces variations in fundamental physical constants. However, detecting such particles becomes highly challenging in the mass range above $10^{-6}\,\text{eV}$, as traditional experiments face severe limitations in response time. In contrast, the matter effect becomes significant in a vast and unexplored parameter space. These effects include (i) a force arising from scattering between ordinary matter and the dark matter wind and (ii) a fifth force between ordinary matter induced by the dark matter background. Using the repulsive quadratic scalar-photon interaction as a case study, we develop a unified framework based on quantum mechanical scattering theory to systematically investigate these phenomena across both perturbative and non-perturbative regimes. Our approach not only reproduces prior results obtained through other methodologies but also covers novel regimes with nontrivial features, such as decoherence effects, screening effects, and their combinations. In particular, we highlight one finding related to both scattering and background-induced forces: the descreening effect observed in the non-perturbative region with large incident momentum, which alleviates the decoherence suppression. Furthermore, we discuss current and proposed experiments, including inverse-square-law tests, equivalence principle tests, and deep-space acceleration measurements. Notably, we go beyond the spherical approximation and revisit the MICROSCOPE constraints on the background-induced force in the large-momentum regime, where the decoherence and screening effects interplay. The ultraviolet models realizing the quadratic scalar-photon interaction are also discussed.

Non-singular matter bouncing cosmological setups are of particular interest since apart from adressing the initial singularity problem they can give rise as well to a nearly scale-invariant curvature power spectrum on scales $k<10^{4}\mathrm{Mpc}^{-1}$, favored by Cosmic Microwave Background (CMB) experiments. Interestingly enough, one can find that within such non-singular bouncing cosmological setups, curvature perturbations grow on super-horizon scales during the matter contracting phase. In this work, we account for the evolution of cosmological perturbations during the transition to the Hot Big Bang expanding Universe, finding at the end naturally enhanced curvature perturbations on very small scales at horizon-crossing time during the expanding phase. These enhanced cosmological perturbations can induce gravitational waves (GWs) due to second order gravitational interactions and collapse as well to form primordial black holes (PBHs), with the latter acting as one of the most viable dark matter candidates. Remarkably, we find an induced GW background with a universal infrared (IR) frequency scaling of $f^2$, in excellent agreement with the recently released $\mathrm{nHz}$ GW data by the NANOGrav collaboration, being potentially detectable as well by other GW observatories such as LISA and ET, depending on the values of the bouncing cosmological parameters at hand.

There are several reasons to support the idea that entropy might be associated to gravity itself. In the absence of a quantum theory of gravity, classical estimators for the gravitational entropy have been proposed. Any viable description of the gravitational entropy should reproduce the Hawking-Bekenstein entropy at the event horizon of black holes. Furthermore, in any black hole transformation, these estimators must satisfy the second law of black hole thermodynamics. In this work, we analyze whether two entropy estimators, one based on the Weyl tensor and the other on the Bel-Robinson tensor, satisfy the second law in the transformation process from a Schwarzschild to a Reissner-Nordström black hole by the absorption of a charge test particle. We also address the inverse process. We show that depending whether the process is reversible or not, both estimators fulfill the second law.

Radio Frequency Interference (RFI) is a known growing challenge for radio astronomy, intensified by increasing observatory sensitivity and prevalence of orbital RFI sources. Spiking Neural Networks (SNNs) offer a promising solution for real-time RFI detection by exploiting the time-varying nature of radio observation and neuron dynamics together. This work explores the inclusion of polarisation information in SNN-based RFI detection, using simulated data from the Hydrogen Epoch of Reionisation Array (HERA) instrument and provides power usage estimates for deploying SNN-based RFI detection on existing neuromorphic hardware. Preliminary results demonstrate state-of-the-art detection accuracy and highlight possible extensive energy-efficiency gains.

Within an inherently classical perspective, there is always an unavoidable energy cost associated with the information deletion and this common lore is at the heart of the Landauer's conjecture that does not impose, per se, any relevant limit on the information acquisition. Although such a mindset should generally apply to systems of any size, its quantum mechanical implications are particularly intriguing and, for this reason, we examine here a minimal physical structure where the system and the environment are described, respectively, by a pair of quantum oscillators coupled by an appropriate Hermitian interaction able to amplify the entropy of the initial state. Since at the onset of the dynamical evolution the system is originally in a pure state, its entropy variation is always positive semidefinite and the Landauer's conjecture should not impose any constraint. Nonetheless, provided the quantum amplification is effective, it turns out that the entropy variation of the system always undershoots the heat transferred to the environment. When the initial thermal state of the environment is characterized by a chemical potential, the entropy growth is bounded both by the particles and by the heat flowing to the environment. The limits deduced in the quantum thermodynamical framework are also scrutinized from a field theory standpoint where species of different spins are copiously produced (especially in a cosmological context) thanks to the rapid variation of the space-time curvature.

Light weakly interacting massive particles (WIMPs), whose masses are in the sub-GeV scale, have been attracting more attention due to the negative results searching for traditional WIMPs. The light WIMPs are expected to produce gamma rays from annihilation in the MeV energy region. Advancements in technology have opened up possibilities to precisely detect MeV gamma rays, leading to the upcoming space-based mission of the Compton Spectrometer and Imager (COSI). We comprehensively and quantitatively study the phenomenology of light WIMPs to determine if the COSI observations will probe their viable model parameter regions. We first construct models to describe light WIMPs based on the minimality and renormalizability of quantum field theory. Next, we impose various constraints on the models obtained from cosmological observations (CMB, BBN) and dark matter searches (accelerator, underground, astrophysical experiments, etc.). Finally, we identify viable parameter regions in each model and discuss whether or not COSI will be sensitive to the parameter regions. We find that a velocity-dependent annihilation cross-section is predicted in some regions, enabling COSI to detect the dark matter signal while avoiding severe constraints from cosmological observations.

Studying the anharmonicity in the infrared (IR) spectra of polycyclic aromatic hydrocarbons (PAHs) at elevated temperatures is important to understand vibrational features and chemical properties of interstellar dust, especially in the James Webb Space Telescope (JWST) era. We take pyrene as an example PAH and investigate how different degrees of superhydrogenation affects the applicability of the harmonic approximation and the role of temperature in IR spectra of PAHs. This is achieved by comparing theoretical IR spectra generated by classical molecular dynamics (MD) simulations and experimental IR spectra obtained via gas-phase action spectroscopy which utilizes the Infrared Multiple Photon Dissociation (IRMPD). All simulations are accelerated by a machine learning interatomic potential, in order to reach first principle accuracies while keeping low computational costs. We have found that the harmonic approximation with empirical scaling factors is able to reproduce experimental band profile of pristine and partially superhydrogenated pyrene cations. However, a MD-based anharmonic treatment is mandatory in the case of fully superhydrogenated pyrene cation for matching theory and experiment. In addition, band shifts and broadenings as the temperature increases are investigated in detail. Those findings may aid in the interpretation of JWST observations on the variations in band positions and widths of interstellar dust.

We present a numerical investigation of primordial black hole (PBH) formation from super-horizon curvature perturbations and the subsequent generation and propagation of sound waves, which can serve as a new source of stochastic gravitational wave backgrounds presented in a companion letter. Using the Misner-Sharp formalism with an excision technique, our simulations extend to significantly later times than previous work and indicate that the near-critical perturbations produce a distinct compression wave featuring both overdense and underdense shells, while significantly supercritical perturbations yield only an underdense shell. We also show that a softer equation of state suppresses the formation of compression waves. Furthermore, the comoving thickness of sound shells remains nearly constant during propagation and scales with the Hubble radius at horizon re-entry, thereby serving as a key link between the gravitational-wave peak frequency and PBH mass in the companion letter. These results offer new insights into the dynamics of PBH formation and suggest potential observational signatures of PBHs in the gravitational wave spectrum from associated sound waves.

We describe a resonant cavity search apparatus for axion dark matter constructed by the Quantum Sensors for the Hidden Sector (QSHS) collaboration. The apparatus is configured to search for QCD axion dark matter, though also has the capability to detect axion-like particles (ALPs), dark photons, and some other forms of wave-like dark matter. Initially, a tuneable cylindrical oxygen-free copper cavity is read out using a low noise microwave amplifier feeding a heterodyne receiver. The cavity is housed in a dilution refrigerator and threaded by a solenoidal magnetic field, nominally 8T. The apparatus also houses a magnetic field shield for housing superconducting electronics, and several other fixed-frequency resonators for use in testing and commissioning various prototype quantum electronic devices sensitive at a range of axion masses in the range $\rm 2.0$ to $\rm 40\,eV/c^2$. We present performance data for the resonator, dilution refrigerator, and magnet, and plans for the first science run.

Data on the cosmic microwave background (CMB) are discriminating between different models of inflation, disfavoring simple monomial potentials whilst being consistent with models whose predictions resemble those of the Starobinsky $R + R^2$ cosmological model. However, this model may suffer from theoretical problems, since it requires a large initial field value, threatening the validity of the effective field theory. This is quantified by the Swampland Distance Conjecture, which predicts the appearance of a tower of light states associated with an effective ultra-violet cutoff. This could be lower than the inflation scale for cases with an extended period of inflation, leading to an additional problem of initial conditions. No-scale supergravity models can reproduce the predictions of the Starobinsky model and accommodate the CMB data at the expense of fine-tuning of parameters at the level of $10^{-5}$. Here, we propose a solution to this problem based on an explicit realisation of the Starobinsky model in string theory, where this `deformation' parameter is calculable and takes a value of order of the one corresponding to the Starobinsky inflaton potential. Within this range, there are parameter values that accommodate more easily the combination of Planck, ACT and DESI BAO data, while also restricting the range of possible inflaton field values, thereby avoiding the swampland problem and predicting that the initial conditions for inflation compatible with the CMB data are generic.