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Millimeter-wave refracting telescopes targeting the degree-scale structure of the cosmic microwave background (CMB) have recently grown to diffraction-limited apertures of over 0.5 meters. These instruments are entirely housed in vacuum cryostats to support their sub-kelvin bolometric detectors and to minimize radiative loading from thermal emission due to absorption loss in their transmissive optical elements. The large vacuum window is the only optical element in the system at ambient temperature, and therefore minimizing loss in the window is crucial for maximizing detector sensitivity. This motivates the use of low-loss polymer materials and a window as thin as practicable. However, the window must simultaneously meet the requirement to keep sufficient vacuum, and therefore must limit gas permeation and remain mechanically robust against catastrophic failure under pressure. We report on the development of extremely thin composite polyethylene window technology that meets these goals. Two windows have been deployed for two full observing seasons on the BICEP3 and BA150 CMB telescopes at the South Pole. On BICEP3, the window has demonstrated a 6% improvement in detector sensitivity., Comment: 20 pages, 12 figures, 4 tables

Tilts of certain elements within a laser interferometer can undesirably couple into measurements as a form of noise, known as tilt-to-length (TTL) coupling. This TTL coupling is anticipated to be one of the primary noise sources in the Laser Interferometer Space Antenna (LISA) mission, after Time Delay Interferometry (TDI) is applied. Despite the careful interferometer design and calibration on the ground, TTL is likely to require in-flight mitigation through post-processing subtraction to achieve the necessary sensitivity. Past research has demonstrated TTL subtraction in simulations through the estimation of 24 linear coupling coefficients using a noise minimization approach. This paper investigates an approach based on performing rotation maneuvers for estimating coupling coefficients with low uncertainties. In this study, we evaluate the feasibility and optimal configurations of such maneuvers to identify the most efficient solutions. We assess the efficacy of TTL calibration maneuvers by modulating either the spacecraft attitude or the Moving Optical Sub-Assembly (MOSA) yaw angle. We found that sinusoidal signals with amplitudes of around 30 nrad and frequencies near 43 mHz are practical and nearly optimal choices for such modulations. Employing different frequencies generates uncorrelated signals, allowing for multiple maneuvers to be executed simultaneously. Our simulations enable us to estimate the TTL coefficients with precision below 15 um/rad (1-sigma, in free space) after a total maneuver time of 20 minutes. The results are compared to the estimation uncertainties that can be achieved without using maneuvers.

A star's spin-orbit angle can give us insight into a system's formation and dynamical history. In this paper, we use MAROON-X observations of the Rossiter-McLaughlin (RM) effect to measure the projected obliquity of the LP 261-75 (also known as TOI-1779) system, focusing on the fully-convective M dwarf LP 261-75A and the transiting brown dwarf LP 261-75C. This is the first obliquity constraint of a brown dwarf orbiting an M dwarf and the seventh obliquity constraint of a brown dwarf overall. We measure a projected obliquity of $5^{+11}_{-10}$ degrees and a true obliquity of $14^{+8}_{-7}$ degrees for the system, meaning that the system is well-aligned and that the star is rotating very nearly edge-on, with an inclination of $90^o\,\pm\,11^o$. The system thus follows along with the trends observed in transiting brown dwarfs around hotter stars, which typically have low obliquities. The tendency for brown dwarfs to be aligned may point to some enhanced obliquity damping in brown dwarf systems, but there is also a possibility that the LP 261-75 system was simply formed aligned. In addition, we note that the brown dwarf's radius ($R_C\,=\,0.9$ R$_J$) is not consistent with the youth of the system or radius trends observed in other brown dwarfs, indicating that LP 261-75C may have an unusual formation history., Comment: 16, pages, 7 figures. Accepted in AJ

We discuss a prediction of the solar activity on a short time-scale applying the method based on a combination of a nonlinear mean-field dynamo model and the artificial neural network. The artificial neural network which serves as a correction scheme for the forecast, uses the currently available observational data (e.g., the 13 month running average of the observed solar sunspot numbers) and the dynamo model output. The nonlinear mean-field $\alpha\,\Omega$ dynamo produces the large-scale magnetic flux which is redistributed by negative effective magnetic pressure instability (NEMPI) producing sunspots and active regions. The nonlinear mean-field dynamo model includes algebraic nonlinearity (caused by the feedback of the growing magnetic field on the plasma motion) and dynamic nonlinearities (related to the dynamics of the magnetic helicity of small-scale magnetic field). We compare the forecast errors with a horizon of 1, 6, 12 and 18 months, for different forecast methods, with the same corrections on the current monthly observations. Our forecast is in good agreement with the observed solar activity, the forecast error is almost stably small over short-medium ranges of forecasting windows. Despite a strong level of chaotic component in the solar magnetic activity we present quantitative evidence that the solar activity on a short range can be stably well predicted, by the joint use of the physically based model with the neural network. This result may have an immediate practical implementation for predictions of various phenomena of solar activity and other astrophysical processes, so may be of interest to a broad community., Comment: 12 pages, 4 figures, 1 table

Heat transport in highly turbulent convection is not well understood. In this paper, we simulate compressible convection in a box of aspect ratio 4 using computationally-efficient MacCormack-TVD finite difference method on single and multi-GPUs, and reach very high Rayleigh number ($\mathrm{Ra}$) -- $10^{15}$ in two dimensions and $10^{11}$ in three dimensions. We show that the Nusselt number $\mathrm{Nu} \propto \mathrm{Ra}^{0.3}$ (classical scaling) that differs strongly from the ultimate-regime scaling, which is $\mathrm{Nu} \propto \mathrm{Ra}^{1/2}$. The bulk temperature drops adiabatically along the vertical even for high $\mathrm{Ra}$, which is in contrast to the constant bulk temperature in Rayleigh-B\'{e}nard convection (RBC). Unlike RBC, the density decreases with height. In addition, the vertical pressure-gradient ($-dp/dz$) nearly matches the buoyancy term ($\rho g$). But, the difference, $-dp/dz-\rho g$, is equal to the nonlinear term that leads to Reynolds number $\mathrm{Re} \propto \mathrm{Ra}^{1/2}$., Comment: 17 pages, 16 figures

We report on the results of performing computational gravitational backreaction on cosmic string loops taken from a network simulation. The principal effect of backreaction is to smooth out small-scale structure on loops, which we demonstrate by various measures including the average loop power spectrum and the distribution of kink angles on the loops. Backreaction does lead to self-intersections in most cases, but these are typically small. An important effect discussed in prior work is the rounding off of kinks to form cusps, but we find that the cusps produced by that process are very weak and do not significantly contribute to the total gravitational-wave radiation of the loop. We comment briefly on extrapolating our results to loops as they would be found in nature., Comment: 26 pages, 11 figures. Power spectrum data available via Zenodo: https://doi.org/10.5281/zenodo.14037540

We use one-dimensional hydrodynamic calculations combined with synthetic stellar population models of the Magellanic Clouds to study the onset of self-excited pulsation in luminous red giants. By comparing the results with OGLE observations in the period-luminosity diagram we are able to link the transition from small-amplitude red giants to semi-regular variables with a shift from stochastic driving to self-excited pulsations. This is consistent with previous studies relating this transition with an increase in mass-loss rate, dust formation, and the appearance of long secondary periods. The luminosity and effective temperature at the onset of pulsation are found to depend on metallicity, hydrogen content, and the adopted mixing length parameter. This confirms the role of partial hydrogen ionization in driving the pulsation, supporting the idea of a heat mechanism similar to that of classical pulsators. We examine the impact of turbulent viscosity, and find clear evidence that it must be adjusted according to the stellar chemical and physical parameters to fully match observations. In order to improve the predictive power of pulsation models, the turbulent viscosity and the temperature scale of pulsating red giants must be jointly calibrated. This is critical for model-based studies of the period-luminosity relations of evolved stars and to exploit their potential as distance and age indicators, in particular given the sensitivity of the onset of pulsation to the envelope composition. The grid of models is made publicly available with a companion interpolation routine., Comment: 14 pages, 6 figures, accepted for publication in the Astrophysical Journal; additional material available at https://zenodo.org/records/14002294

Spokes are localized clouds of fine particles that appear over the outer part of Saturn's B ring. Over the course of the Cassini Mission, the Imaging Science Subsystem (ISS) obtained over 20,000 images of the outer B ring, providing the most comprehensive data set for quantifying spoke properties currently available. Consistent with prior work, we find that spokes typically appear as dark features when the lit side of the rings are viewed at low phase angles, and as bright features when the rings are viewed at high phase angles or the dark side of the rings are observed. However, we also find examples of spokes on the dark side of the rings that transition between being brighter and darker than the background ring as they move around the planet. Most interestingly, we also identify spokes that appear to be darker than the background ring near their center and brighter than the background ring near their edges. These "mixed spokes" indicate that the particle size distribution can vary spatially within a spoke. In addition, we document seasonal variations in the overall spoke activity over the course of the Cassini mission using statistics derived from lit-side imaging sequences. These statistics demonstrate that while spokes can be detected over a wide range of solar elevation angles, spoke activity increases dramatically when the Sun is within 10 degrees of the ring plane., Comment: 25 pages, 13 figures, accepted for publication in the Planetary Science Journal

Understanding of cloud microphysics and the evolution of cloud structures in sub-stellar atmospheres remains a key challenge in the JWST era. The abundance of new JWST data necessitates models that are suitable for coupling with large-scale simulations, such as general circulation models (GCMs), in order to fully understand and assess the complex feedback effects of clouds on the atmosphere, and their influence on observed spectral and variability characteristics. We aim to develop a 2-moment, time-dependent bulk microphysical cloud model that is suitable for GCMs of sub-stellar atmospheres. We derive a set of moment equations for the particle mass distribution and develop a microphysical cloud model employing a 2-moment approach. We include homogeneous nucleation, condensation, and collisional microphysical processes that evolve the moments of a particle size distribution in time. We couple our new 2-moment scheme with the Exo-FMS GCM to simulate the evolution of KCl clouds in a Tint = 400 K, log g = 4.25 Y-dwarf atmosphere and examine the effect of cloud opacity on the atmospheric characteristics. Our results show a generally homogeneous global KCl cloud, with only slight variations occurring in the equatorial regions. The atmosphere is generally sluggish and stagnant, with near-zero vertical velocities throughout most of the atmosphere. Only very small grains ~0.01 um remain lofted in the atmosphere. Our results conform with dynamical theories for this parameter regime, with our model showing minimal (~0.2%) spectral variability at mid-infrared wavelengths. Our study demonstrates that the 2-moment bulk cloud microphysical scheme is a highly suitable method for investigating cloud characteristics and feedback in GCMs and other large scale simulations of sub-stellar atmospheres. Split moment schemes and mixed material grains will be explored in a follow up study., Comment: Submitted to A&A

The characterization of magnetic fields within molecular clouds is fundamental to understanding star formation processes. Accurately gauging the three-dimensional structure of these fields presents a challenge, as observational techniques such as dust polarization and the Zeeman effect each provide only partial information on the orientation and line-of-sight strength, respectively. By analyzing a suite of AREPO simulations, this paper investigates how observables can relate to underlying physical properties to derive a more comprehensive picture of the magnetic field's inclination angle and strength, specifically in regions where both dust polarization and Zeeman data are available. To demonstrate the method, we produce synthetic observations of the polarization angle dispersion and line-of-sight Alfv\'en Mach Number and explore the behavior of the inclination angle, $\gamma$, and strength of the magnetic field in regions where both Zeeman and dust polarization data are available. We find that dust polarization data can be used to determine the inclination angle if the cloud is known to be trans-Alfv\'enic or sub-Alfv\'enic. The strength of the magnetic field relative to turbulence can be estimated by comparing polarization observations to Zeeman observations. Comparing the dispersion of the polarization angle to the estimated line-of-sight Alfv\'en Mach Number provides clues about the strength of the magnetic field and, consequently, the orientation of the magnetic field., Comment: 16 pages, 12 figures, 1 table

Many magnetic white dwarfs exhibit a polarised spectrum that periodically varies as the star rotates because the magnetic field is not symmetric about the rotation axis. In this work, we report the discovery that while weakly magnetic white dwarfs of all ages with M < 1Mo show polarimetric variability with a period between hours and several days, the large majority of magnetic white dwarfs in the same mass range with cooling ages older than 2 Gyr and field strengths > 10 MG show little or no polarimetric variability. This could be interpreted as extremely slow rotation, but a lack of known white dwarfs with measured periods longer than two weeks means that we do not see white dwarfs slowing their rotation. We therefore suggest a different interpretation: old strongly magnetic white dwarfs do not vary because their fields are roughly symmetric about the rotation axes. Symmetry may either be a consequence of field evolution or a physical characteristic intrinsic to the way strong fields are generated in older stars. Specifically, a strong magnetic field could distort the shape of a star, forcing the principal axis of maximum inertia away from the spin axis. Eventually, as a result of energy dissipation, the magnetic axis will align with the angular momentum axis. We also find that the higher-mass strongly magnetised white dwarfs, which are likely the products of the merging of two white dwarfs, may appear as either polarimetrically variable or constant. This may be the symptom of two different formation channels or the consequence of the fact that a dynamo operating during a merger may produce diverse magnetic configurations. Alternatively, the massive white dwarfs with constant polarisation may be rotating with periods much shorter than the typical exposure times of the observations., Comment: Accepted by A&A

X-Ray bursts (XRBs) are powerful thermonuclear events on the surface of accreting neutron stars (NSs), which can synthesize intermediate-mass elements. Although the high surface gravity prevents an explosive ejection, a small fraction of the envelope may be ejected by radiation-driven winds. In our previous works, we have developed a non-relativistic radiative wind model and coupled it to an XRB hydrodynamic simulation. We now apply this technique to another model featuring consecutive bursts. We determine the mass-loss and chemical composition of the wind ejecta. Results show that, for a representative XRB, about $0.1\%$ of the envelope mass is ejected per burst, at an average rate of $3.9 \times 10^{-12}\,M_\odot \texttt{yr}^{-1}$. Between $66\%$ and $76\%$ of the ejecta composition is $^{60}$Ni, $^{64}$Zn, $^{68}$Ge, $^{4}$He and $^{58}$Ni. We also report on the evolution of observational quantities during the wind phase and simulate NICER observations that resemble those of 4U 1820-40., Comment: 6 pages, 3 figures, part of 2024 XMM-Newton Science Conference Proceedings, Madrid

We calculate the two-loop corrections in curvature perturbation power spectrum in models of single field inflation incorporating an intermediate USR phase employed for PBHs formation. Among the total eleven one-particle irreducible Feynman diagrams, we calculate the corrections from the ``double scoop" two-loop diagram involving two vertices of quartic Hamiltonians. We demonstrate that the fractional two-loop correction in power spectrum scales like the square of the fractional one-loop correction. We confirm our previous findings that the loop corrections become arbitrarily large when the transition from the USR phase to the final attractor phase is very sharp. This suggests that in order for the analysis to be under perturbative control against the loop corrections, one requires a mild transition with a long enough relaxation period towards the final attractor phase., Comment: 21 pages, 2 figures. arXiv admin note: text overlap with arXiv:2403.03841

Thermal nonequilibrium (TNE) is a condition of the plasma in the solar corona in which the local rate of energy loss due to radiation increases to the point that it cannot be sustained by the various heating terms acting on the plasma, precluding the existence of a steady state. The limit cycles of precipitation and evaporation that result from TNE have been simulated in 1D models of coronal loops, as well as 2D and 3D models of the solar chromosphere and lower corona. However, a careful study of TNE in the solar wind has not been performed until now. Here we demonstrate that for suitable combinations of local and global heating rates it is possible for the plasma to exhibit a TNE condition, even in the context of a transonic solar wind with appreciable mass and energy fluxes. This implies limits on the amount of foot-point heating that can be withstood under steady-state conditions in the solar wind, and may help to explain the variability of solar wind streams that emanate from regions of highly concentrated magnetic flux on the solar surface. The implications of this finding pertain to various sources of high-density solar wind, including plumes that form above regions of mixed magnetic polarity in polar coronal holes and the slow solar wind (SSW) that emanates from coronal hole boundaries.

Fixed target experiments where beam electrons are focused upon a thin target have shown great potential for probing new physics, including the sub-GeV dark matter (DM) paradigm. However, a signal in future experiments such as the light dark matter experiment (LDMX) would require an independent validation to assert its DM origin. To this end, we propose to combine LDMX and next generation DM direct detection (DD) data in a four-step analysis strategy, which we here illustrate with Monte Carlo simulations. In the first step, the hypothetical LDMX signal (i.e. an excess in the final state electron energy and transverse momentum distributions) is $\textit{recorded}$. In the second step, a DM DD experiment operates with increasing exposure to test the DM origin of the LDMX signal. Here, LDMX and DD data are simulated. In the third step, a posterior probability density function (pdf) for the DM model parameters is extracted from the DD data, and used to $\textit{predict}$ the electron recoil energy and transverse momentum distributions at LDMX. In the last step, $\textit{predicted}$ and $\textit{recorded}$ electron recoil energy and transverse momentum distributions are compared in a chi-square test. We present the results of this comparison in terms of a threshold exposure that a DD experiment has to operate with to assert whether $\textit{predicted}$ and $\textit{recorded}$ distributions $\textit{can}$ be statistically dependent. We find that this threshold exposure grows with the DM particle mass, $m_\chi$. It varies from 0.012 kg-year for a DM mass of $m_\chi=4$ MeV to 1 kg-year for $m_\chi=25$ MeV, which is or will soon be within reach.

This study explores a two-component dark matter model in which one component, heavier dark matter, annihilates into a lighter dark matter. The lighter dark matter is expected to generate detectable signals in detectors due to its enhanced momentum, enabling direct detection even for MeV-scale dark matter. We investigate the effectiveness of directional direct detections, especially the nuclear emulsion detector NEWSdm, in verifying these boosted dark matter particles through nuclear recoil. In particular, we focus on light nuclei, such as protons and carbon, as suitable targets for this detection method due to their high sensitivity to MeV-scale dark matter. By modeling the interactions mediated by a dark photon in a hidden U(1)$_D$ gauge symmetry framework, we calculate the expected dark matter flux and scattering rates for various detector configurations. Our results show that nuclear emulsions have the potential to yield distinct, direction-sensitive dark matter signals from the Galactic center, providing a new way to probe low-mass dark matter parameter spaces that evade conventional detection methods., Comment: 17 pages, 10 figures, 3 tables

Blazars are a subclass of active galactic nuclei (AGNs) with relativistic jets pointing toward the observer. They are notable for their flux variability at all observed wavelengths and timescales. Together with simultaneous measurements at lower energies, the very-high-energy (VHE) emission observed during blazar flares may be used to probe the population of accelerated particles. However, optimally triggering observations of blazar high states can be challenging. Notable examples include identifying a flaring episode in real time and predicting VHE flaring activity based on lower energy observables. For this purpose, we have developed a novel deep learning analysis framework, based on data-driven anomaly detection techniques. It is capable of detecting various types of anomalies in real-world, multiwavelength light curves, ranging from clear high states to subtle correlations across bands. Based on unsupervised anomaly detection and clustering methods, we differentiate source variability from noisy background activity, without the need for a labeled training dataset of flaring states. The framework incorporates measurement uncertainties and is robust given data quality challenges, such as varying cadences and observational gaps. We evaluate our approach using both historical data and simulations of blazar light curves in two energy bands, corresponding to sources observable with the Fermi Large Area Telescope, and the upcoming Cherenkov Telescope Array Observatory (CTAO). In a statistical analysis, we show that our framework can reliably detect known historical flares.

We investigate the impact of beam chromaticity, i.e., the frequency dependence of the beam window function, on cosmological and astrophysical parameter constraints from CMB power spectrum observations. We show that for future high-resolution CMB measurements it is necessary to include a color-corrected beam for each sky component with a distinct spectral energy distribution. We introduce a formalism able to easily implement the beam chromaticity in CMB power spectrum likelihood analyses and run a case study using a Simons Observatory (SO) Large Aperture Telescope-like experimental setup and within the public SO software stack. To quantify the impact, we assume that beam chromaticity is present in simulated spectra but omitted in the likelihood analysis. We find that, for passbands of fractional width $\Delta \nu/\nu \sim 0.2$, neglecting this effect leads to significant biases, with astrophysical foreground parameters shifting by more than $2\sigma$ and cosmological parameters by significant fractions of the error., Comment: 10 pages, 6 figures

We present the observations of a quiescent filament eruption and its deflection from the radial direction. The event occurred in the southern solar hemisphere on 2021 May 9 and was observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO), by the STEREO A Observatory and GONG. Part of the filament erupted in the west direction, while major part of the filament deviated towards east direction. LASCO observed a very weak CME towards the west direction where it faded quickly. Moreover, the eruption was associated with CME observed by STEREO A COR1 and COR2. Our observations provide the evidence that the filament eruption was highly non-radial in nature., Comment: Accepted in the Proceedings of IAUS 388

A sharp step on a chaotic potential can enhance primordial curvature fluctuations on smaller scales to the $\mathcal{O}(10^{-2})$ to form primordial black holes (PBHs). The present study discusses an inflationary potential with a sharp step that results in the formation of PBHs in four distinct mass ranges. Also this inflationary model allows the separate consideration of observable parameters $n_s$ and $r$ on the CMB scale from the physics at small scales, where PBHs formation occur. In this work we computed the fractional abundance of PBHs ($f_{PBH}$) using the GLMS approximation of peak theory and also the Press-Schechter (PS) formalism. In the two typical mass windows, $10^{-13}M_\odot$ and $10^{-11}M_\odot$, $f_{PBH}$ calculated using the GLMS approximation is nearly equal to 1 and that calculated via PS is of $10^{-3}$. In the other two mass windows $1M_\odot$ and $6M_\odot$, $f_{PBH}$ obtained using GLMS approximation is 0.01 and 0.001 respectively, while $f_{PBH}$ calculated via PS formalism yields $10^{-5}$ and $10^{-6}$. The results obtained via GLMS approximation are found to be consistent with observational constraints. A comparative analysis of $f_{PBH}$ obtained using the GLMS perspective and the PS formalism is also included.

Context: Timing of pulsar PSR J0337+1715 provides a unique opportunity to test the strong equivalence principle (SEP) with a strongly self-gravitating object. This is due to its unique situation in a triple stellar system with two white dwarfs. Aims: Our previous study suggested the presence of a strong low-frequency signal in the timing residuals. We set out to model it on a longer dataset in order to determine its nature and improve accuracy. Methods: Three models are considered: chromatic or achromatic red-noise, and a small planet in a hierarchical orbit with the triple stellar system. These models are implemented in our numerical timing model. We perform Bayesian inference of posterior distributions. Best fits are compared using information-theoretic criteria. Results: Chromatic red noise from dispersion-measure variations is ruled out. Achromatic red noise or a planet in keplerian orbit provide the best fits. If it is red noise then it appears exceptionally strong. Assuming the presence of a planet, we obtain a marginal detection of mutual interactions which allows us to constrain its mass to $\sim 0.5 M_{\rm Moon}$ as well as its inclination. The latter is intriguingly coincident with a Kozai resonance. We show that a longer observation span will ultimately lead to a clear signature of the planet model due to its mutual interactions with the triple system. We produce new limits on SEP violation: $|\Delta| < 1.5\cdot 10^{-6}$ or $|\Delta| < 2.3\cdot 10^{-6}$ at 95\% confidence level under the planet or red-noise hypothesis, respectively. This model dependence emphasises the need for additional data and model selection. As a by-product, we estimate a rather low supernova kick velocity of $\sim 110-125 \rm km/s$, strengthening the idea that it is a necessary condition for the formation of pulsar triple systems., Comment: Astronomy and Astrophysics - A\&A, In press

We aim to provide more insights into the applicability to solar coronal seismology of the much-studied discrete leaky modes (DLMs) in classic analyses. Under linear ideal pressureless MHD, we examine two-dimensional (2D) axial fundamental kink motions that arise when localized velocity exciters impact some symmetric slab equilibria. Continuous structuring is allowed for. A 1D initial value problem (IVP) is formulated in conjunction with an eigenvalue problem (EVP) for laterally open systems, with no strict boundary conditions (BCs) at infinity. The IVP is solved by eigenfunction expansion, allowing a clear distinction between the contributions from proper eigenmodes and improper continuum eigenmodes. Example solutions are offered for parameters typical of active region loops. Our solutions show that the system evolves towards long periodicities due to proper eigenmodes (of order the axial Alfven time), whereas the interference of the improper continuum may lead to short periodicities initially (of order the lateral Alfven time). Specializing to the slab axis, we demonstrate that the proper contribution strengthens with the density contrast, but may occasionally be stronger for less steep density profiles. Short periodicities are not guaranteed in the improper contribution, the details of the initial exciter being key. When identifiable, these periodicities tend to agree with the oscillation frequencies expected for DLMs, despite the differences in the BCs between our EVP and classic analyses. The eigenfunction expansion approach enables all qualitative features to be interpreted as the interplay between the initial exciter and some response function, the latter solely determined by the equilibria. Classic theories for DLMs can find seismological applications, with time-dependent studies offering additional ways for constraining initial exciters., Comment: accepted for publication in A&A

Over the last three decades, the ground-based technique of imaging atmospheric Cherenkov telescopes has established itself as a powerful scientific discipline. About 250 very high gamma-ray sources of both galactic and extragalactic origin have been discovered, largely thanks to this technique. The study of these sources provides clues to many fundamental questions in astrophysics, astroparticle physics, cosmic ray physics and cosmology. The current generation of telescopes in operation offers solid performance. Further improvements in this technique led to the next generation large-scale instrument known as the Cherenkov Telescope Array (CTA). In its final configuration, the sensitivity of CTA will be several times higher than that of the current best instruments VERITAS, H.E.S.S. and MAGIC. This article is devoted to presenting the technological developments that have shaped this technique and led to its current success., Comment: 29 pages, 7 figures. Review Chapter of Special Issue 'High-Energy Gamma-Ray Astronomy', MDPI Universe, Editors U. Barres de Almeida, M. Doro

The Arecibo Message was a brief binary-encoded communication transmitted into space from the Arecibo Observatory on November 16, 1974, intended to demonstrate human technological prowess. In late 2018, to commemorate the 45th anniversary of this message, the Arecibo Observatory initiated the New Arecibo Message competition. Following a series of challenges, our Boriken Voyagers team was recognized as the winner of the competition in August 2020. Although the primary objective of the competition was to conceptualize rather than transmit a message, the collapse of the Arecibo Telescope in December 2020 precluded any subsequent transmission efforts. Therefore, to commemorate the 50th anniversary of the Arecibo Message, this paper presents the Last Arecibo Message, as originally developed for the Arecibo Telescope. If the original message says "we are a form of life reaching out to connect", our message says "we are ready to explore the universe together." The prospect of transmitting this or a similar message remains an open question., Comment: 12 pages, 4 figures. Additional content is available at https://phl.upr.edu/message/

We revisit unflavoured leptogenesis in the seesaw model applying recent improvements in the computation of $CP$-conserving and $CP$-violating equilibration rates. These are relevant for the relativistic regime of the sterile Majorana fermions and the dynamics of the Standard Model particles acting as spectator processes. In order to probe the regime of large (${\cal O}(10^2)$) washout parameters, we add $\Delta L = 2$ washout processes, which we derive in the CTP-formalism. We then perform a parameter scan of the final baryon asymmetry and find a constraint $m_{\text{lightest}} \lesssim 0.15 \, \rm eV$ on the absolute neutrino mass scale, which is slightly less stringent than previously reported bounds obtained without the aforementioned improvements. The relaxation of the bounds is mainly due to partially equilibrated spectator fields, which protect part of the asymmetry from washout and lead to larger final asymmetries., Comment: 14 pages, 4 figures

We present contemporaneous high-angular-resolution millimeter imaging and visible polarimetric imaging of the nearby asymptotic giant branch (AGB) star W Hya to better understand the dynamics and dust formation within a few stellar radii. The star W Hya was observed in two vibrationally excited H2O lines at 268 and 251 GHz with ALMA at a spatial resolution of 16 x 20 mas and at 748 and 820 nm at a resolution of 26 x 27 mas with the VLT/SPHERE-ZIMPOL. ALMA's high spatial resolution allowed us to image strong emission of the vibrationally excited H2O line at 268 GHz (v2 = 2, J_K_a,K_c = 6_5,2 - 7_4,3) over the stellar surface instead of absorption against the continuum, which is expected for thermal excitation. Strong, spotty emission was also detected along and just outside the stellar disk limb at an angular distance of ~40 mas (~1.9 stellar radii), extending to ~60 mas (~2.9 stellar radii). Another H2O line (v2 = 2, J_K_a,K_c = 9_2,8 - 8_3,5) at 251 GHz with a similar upper-level energy was tentatively identified, which shows absorption over the stellar surface. This suggests that the emission over the surface seen in the 268 GHzH2O line is suprathermal or even maser emission. The estimated gas temperature and H2O density are consistent with the radiatively pumped masers. The 268 GHz H2O line reveals global infall at up to ~15 km/s within 2--3 stellar radii, but outflows at up to ~8 km/s are also present. The polarized intensity maps obtained in the visible reveal clumpy dust clouds forming within ~40 mas (~1.9 stellar radii) with a particularly prominent cloud in the SW quadrant and a weaker cloud in the east. The 268 GHz H2O emission overlaps very well with the visible polarized intensity maps, which suggests that both the nonthermal and likely maser H2O emission and the dust originate from dense, cool pockets in the inhomogeneous atmosphere within ~2--3 stellar radii., Comment: 10 pages, 7 figures, published in Astronomy and Astrophysics

Accurate, precise, and computationally efficient removal of unwanted activity that exists as a combination of periodic, quasi-periodic, and non-periodic systematic trends in time-series photometric data is a critical step in exoplanet transit analysis. Throughout the years, many different modeling methods have been used for this process, often called "detrending." However, there is no community-wide consensus regarding the favored approach. In order to mitigate model dependency, we present an ensemble-based approach to detrending via community-of-models and the $\texttt{democratic detrender}$: a modular and scalable open-source coding package that implements ensemble detrending. The $\texttt{democratic detrender}$ allows users to select from a number of packaged detrending methods (including cosine filtering, Gaussian processes, and polynomial fits) or provide their own set of detrended light curves via methods of their choosing. The $\texttt{democratic detrender}$ then combines the resulting individually detrended light curves into a single method marginalized (via median selection) light curve. Additionally, the $\texttt{democratic detrender}$ inflates the uncertainties of each time-series data point using information from the median absolute deviation between the individually detrended light curve, propagating information into the final detrended light curve about the added uncertainty due to the correctness of the underlying models., Comment: 15 pages, 10 figures, submitted to ApJS. For source code, documentation, and tutorials, see https://github.com/dyahalomi/democratic_detrender

We explore the potential of gravitational waves (GWs) to probe the pre-BBN era of the early universe, focusing on the effects of energy injection. Specifically, we examine a hidden sector alongside the Standard Model that undergoes a strong first-order phase transition (FOPT), producing a GW signal. Once the phase transition has completed, energy injection initiates reheating in the hidden sector, which positions the hidden sector field so that additional phase transitions can occur. This can result in a total of three distinct phase transitions with a unique three-peak GW spectrum. Among these transitions, the first and third are of the standard type, while the intermediate second transition is inverted, moving from a broken to an unbroken phase. Using polynomial potentials as a framework, we derive analytical relations among the phase transition parameters and the resulting GW spectrum. Our results indicate that the second and third transitions generate GWs with higher amplitudes than the first, with a peak frequency ratio differing by up to an order of magnitude. This three-peak GW spectrum is detectable by upcoming facilities such as LISA, BBO, and UDECIGO. Notably, the phenomenon is robust across various potentials and model parameters, suggesting that hidden sector GWs provide a powerful tool for exploring new physics scenarios in the pre-BBN era.

Transit timing variations (TTVs) are observed for exoplanets at a range of amplitudes and periods, yielding an ostensibly degenerate forest of possible explanations. We offer some clarity in this forest, showing that systems with a distant perturbing planet preferentially show TTVs with a dominant period equal to either the perturbing planet's period or half the perturbing planet's period. We demonstrate that planet induced TTVs are not expected with TTV periods below this exoplanet edge (lower period limit) and that systems with TTVs that fall below this limit likely contain additional mass in the system. We present an explanation for both of these periods, showing that both aliasing of the conjunction induced synodic period and the near $1:2$ resonance super-period and tidal effects induce TTVs at periods equal to either the perturber's orbit or half-orbit. We provide three examples of known systems for which the recovered TTV period induced by a distant perturbing planet is equal to the perturber's orbital period or half its orbital period. We then investigate $\textit{Kepler}$ two-planet systems with TTVs and identify 13 two-planet systems with TTVs below this TTV period lower limit -- thus potentially uncovering the gravitational influence of new planets and/or moons. We conclude by discussing how the exoplanet edge effects can be used to predict the presence of distance companion planets, in situations where TTVs are detected and where nearby companions can be ruled out by additional observations, such as radial velocity data., Comment: 18 pages, 7 figures, submitted to ApJL

The primary objective of this study was to utilize the newest Gaia FPR catalogue containing ultra-precise asteroid astrometry spanning over 66 months to detect the Yarkovsky effect, a non-gravitational acceleration that affects the orbits of small asteroids. Moreover, this study examines close approaches of near-Earth asteroids by comparing orbits calculated using the Gaia data. We used the conventional least-squares orbit computation method available in the OrbFit software. We used the latest Gaia Focused Product Release, complemented by data from the Minor Planet Center and radar astrometry from the Jet Propulsion Laboratory. We fitted orbital parameters for 446 Near-Earth Asteroids, including the additional non-gravitational transverse acceleration to model the Yarkovsky effect. Furthermore, we compared the results obtained using different datasets: Gaia Focused Product Release and the previous Gaia Data Release 3. We detected a robust Yarkovsky effect in 43 NEAs. As expected, we found an improvement in the orbital elements uncertainty and in the signal-to-noise ratio of the Yarkovsky effect detections when using the current Gaia FPR with double the observing arc compared to the DR3 catalog. We also found nine additional reliable detections of the Yarkovsky effect when using the new Gaia FPR catalog. Including the Yarkovsky effect in the force model can be important to reliably estimate close approach distances of near-Earth asteroids. Several of the detected Yarkovsky drifts already have a signal-to-noise ratio greater than 10, which is high enough for their Yarkovsky effect to be included in their reliable long-term orbital evolution, close approach, and Earth impact analysis. The final Gaia catalog may provide a much higher number of high signal-to-noise ratio detections of the Yarkovsky effect., Comment: 8 pages, 6 figures, accepted at Astronomy & Astrophysics. This study uses the latest Gaia FPR catalogue to assess the detection of the Yarkovsky effect on NEAs, comparing results with previous data releases and emphasizing improvements in orbital determination and close-approach predictions

Early dark energy solutions to the Hubble tension introduce an additional scalar field which is frozen at early times but becomes dynamical around matter-radiation equality. In order to alleviate the tension, the scalar's share of the total energy density must rapidly shrink from $\sim 10\%$ at the onset of matter domination to $\ll 1\%$ by recombination. This typically requires a steep potential that is imposed $\textit{ad hoc}$ rather than emerging from a concrete particle physics model. Here, we point out an alternative possibility: a homogeneous scalar field coupled quadratically to a cosmological background of light thermal relics (such as the Standard Model neutrino) will acquire an effective potential which can reproduce the dynamics necessary to alleviate the tension. We identify the relevant parameter space for this "thermo-coupled" scenario and study its unique phenomenology at the background level, including the back-reaction on the neutrino mass. Follow-up numerical work is necessary to determine the constraints placed on the model by early-time measurements., Comment: 6 pages, 3 figures

Stars in close binaries are tidally distorted, and this has a strong effect on their pulsation modes. We compute the mode frequencies and geometries of tidally distorted stars using perturbation theory, accounting for the effects of the Coriolis force and the coupling between different azimuthal orders $m$ of a multiplet induced by the tidal distortion. For tidally coupled dipole pressure modes, the tidal coupling dominates over the Coriolis force and the resulting pulsations are ``triaxial", with each of the three modes in a multiplet ``tidally tilted" to be aligned with the one of the three principal axes of the star. The observed amplitudes and phases of the dipole modes aligned orthogonal to the spin axis are modulated throughout the orbit, producing doublets in the power spectrum that are spaced by exactly twice the orbital frequency. Quadrupole modes have similar but slightly more complex behavior. This amplitude modulation allows for mode identification which can potentially enable detailed asteroseismic analyses of tidally tilted pulsators. Pressure modes should exhibit this behavior in stellar binaries close enough to be tidally synchronized, while gravity modes should remain aligned with the star's spin axis. We discuss applications to various types of pulsating stars, and the relationship between tidal tilting of pulsations and the ``single-sided" pulsations sometimes observed in very tidally distorted stars., Comment: Submitted to ApJ, comments welcome!

Type Ia supernovae (SNe Ia) correspond to the thermonuclear explosion of a carbon-oxygen white dwarf (C-O WD) star in a binary system, triggered by the accretion of material from another star, or the merger/collision with a secondary WD. Their phenomenal luminosity -- several billion times that of the sun -- has motivated their use as cosmological distance indicators and led to the discovery of the accelerated expansion of the universe. SNe Ia are also the main producers of iron and hence play a fundamental role in the chemical evolution of galaxies. While recent observations have confirmed the basic theoretical picture of an exploding C-O WD star whose luminosity is powered by the radioactive decay of $^{56}$Ni, a number of uncertainties remain concerning the nature of the binary companion and the explosion mechanism. Several lines of evidence point towards the existence of multiple progenitor channels in order to explain the full range of the observed diversity. A complete physical understanding of these energetic stellar explosions remains a long-lasting goal of modern astrophysics., Comment: This is a pre-print of a chapter for the Encyclopedia of Astrophysics (edited by Ilya Mandel, section editor Jeffrey Andrews) to be published by Elsevier as a Reference Module. 18 pages, 7 figures

New results on the behavior of the double-mode RR Lyrae V338 Boo are presented. The Transiting Exoplanet Survey Satellite (TESS) observed this star again in 2022, and an observing campaign of the American Association of Variable Star Observers (AAVSO) was completed after the TESS observations as a follow-up. We find that the first overtone pulsation mode in this star completely disappears during the TESS observing window. This mode reappears at the end of the TESS observations, and the AAVSO observing campaign shows that in the months that followed, the first overtone mode was not only present, but was the dominant mode of pulsation. This star, and potentially others like it, could hold the key to finally solving the mystery of the Blazhko effect in RR Lyrae., Comment: 11 pages, 7 figures; published in ApJ

The mass of galaxy clusters is a critical quantity for probing cluster cosmology and testing theories of gravity, but its measurement could be biased given assumptions are inevitable. In this paper, we employ and compare two mass proxies for galaxy clusters: thermodynamics of the intracluster medium and kinematics of member galaxies. We select 22 galaxy clusters from the cluster catalog in the first SRG/eROSITA All-Sky Survey (eRASS1) that have sufficient optical and near-infrared observations. We generate multi-band images in the energy range of (0.3, 7) keV for each cluster, and derive their temperature profiles, gas mass profiles and hydrostatic mass profiles using a parametric approach that does not assume dark matter halo models. With spectroscopically confirmed member galaxies collected from multiple surveys, we numerically solve the spherical Jeans equation for their dynamical mass profiles. Our results quantify the correlation between dynamical mass and line-of-sight velocity dispersion with an rms scatter of 0.14 dex. We find the two mass proxies lead to roughly the same total mass, with no observed systematic bias. As such, the $\sigma_8$ tension is not specific to hydrostatic mass or weak lensing shears, but also appears with galaxy kinematics. We also compare our hydrostatic masses with the latest weak lensing masses inferred with scaling relations. The comparison shows the weak lensing mass is significantly higher than our hydrostatic mass by $\sim$110%. This might explain the significantly larger value of $\sigma_8$ from the latest measurement using eRASS1 clusters than almost all previous estimates in the literature. Finally, we test the radial acceleration relation (RAR) established in disk galaxies. We confirm the missing baryon problem in the inner region of galaxy clusters using three independent mass proxies for the first time., Comment: 14 pages, 9 figures, 2 tables, with 12-page appendix for additional figures and tables. Accepted for publication in A&A

We present the first set of high-resolution, hydrodynamical cosmological simulations of galaxy formation in a Fuzzy Dark Matter (FDM) framework. These simulations were performed with a new version of the GASOLINE2 code, known as FUZZY-GASOLINE, which can simulate quantum FDM effects alongside a comprehensive baryonic model that includes metal cooling, star formation, supernova feedback, and black hole physics, previously used in the NIHAO simulation suite. Using thirty zoom-in simulations of galaxies with halo masses in the range $10^9 \lesssim M_{\text{halo}}/M_{\odot} \lesssim 10^{11}$, we explore how the interplay between FDM quantum potential and baryonic processes influences dark matter distributions and observable galaxy properties. Our findings indicate that both baryons and low-mass FDM contribute to core formation within dark matter profiles, though through distinct mechanisms: FDM-induced cores emerge in all haloes, particularly within low-mass systems at high redshift, while baryon-driven cores form within a specific mass range and at low redshift. Despite these significant differences in dark matter structure, key stellar observables such as star formation histories and velocity dispersion profiles remain remarkably similar to predictions from the Cold Dark Matter (CDM) model, making it challenging to distinguish between CDM and FDM solely through stellar observations., Comment: 13 pages, 8 figures, 6 tables. Paper submitted to MNRAS

We introduce the Data Analysis Pipeline (DAP) for the Sloan Digital Sky Survey V (SDSS-V) Local Volume Mapper (LVM) project, referred to as the LVM-DAP. We outline our methods for recovering both stellar and emission line components from the optical integral field spectroscopy, highlighting the developments and changes implemented to address specific challenges of the data set. The observations from the LVM project are unique because they cover a wide range of physical resolutions, from approximately 0.05 pc to 100 pc, depending on the distance to the targets. This, along with the varying number of stars sampled in each aperture (ranging from zero, just one of a few, to thousands), presents challenges in using previous spectral synthesis methods and interpreting the spectral fits. We provide a detailed explanation of how we model the stellar content and separate it from the ionized gas emission lines. To assess the accuracy of our results, we compare them with both idealized and more realistic simulations, highlighting the limitations of our methods. We find that the DAP robustly correct for stellar continuum features and recover emission line parameters (e.g. flux, equivalent width, systemtic velocity and velocity dispersion) with a precision and accuracy that fulfill the requirements of the primary goal of the analysis. In addition, the recovered stellar parameters are reliable for single stars, the recovery of integrated populations is less precise. We conclude with a description of the data products we provide, instructions for downloading and using our software, and a showcase illustrating the quality of the data and the analysis on a deep exposure taken on the Huygens region at the center of the Orion Nebula., Comment: 35 pages, 17 figures, 8 tables, accepted for publication in AJ

Silicon photo-multipliers (SiPM) have been replacing traditional photomultiplier tubes in most light sensing applications. However, when large detection surface coverage is needed, photomultipliers (PMTs) are still the preferred choice. The main reasons are the sensor thermal noise and the duration of the fast component of its signal, both increasing with the sensor surface. In this work we propose an application specific integrated circuit (ASIC), called Fast ANalog SiPM Integrated Circuit (FANSIC), for the readout of large SiPMs addressing these limitations. The ASIC has an active summation stage, which allows to divide a large detection surface into smaller ones offering faster response both in single ended and differential outputs. The high input bandwidth allows to reach full-width-half-maximum (FWHM) signals or the order of 3--5 ns which limits the impact of internal and external uncorrelated noise. The results of the first implementation of FANSIC, designed in CMOS 65 nm technology, is described in this paper., Comment: 21 pages, 17 figures, journal

We study neutrino, muon, and gamma-ray fluxes in extraterrestrial environments in our Solar System via semi-analytical estimates and Monte Carlo simulations. In sites with negligible atmosphere, we find a strong reduction in the cosmic-ray-induced neutrino and muon fluxes relative to their intensities on Earth. Neutrinos with energies between 50 MeV and 100 TeV show particularly strong suppression, by as much as 10$^3$, even at shallow depths. The solar neutrino suppression increases as the square of the site's distance from the Sun. Natural radiation due to nuclear decay is also expected to be lower in many of these locations and may be reduced to effectively negligible levels in the liquid water environments. The sites satisfying these characteristics represent an opportunity for greatly extending the physics reach of underground searches in fundamental physics, such as searches for WIMP Dark Matter, neutrinoless double-beta decay, the diffuse supernova neutrinos, and neutrinos from nearby supernova. As a potential near-term target, we propose a measurement of muon and gamma-ray fluxes in an accessible underground lunar site such as the Mare Tranquillitatis Pit to perform a first measurement of the prompt component in cosmic-ray-induced particle production, and to constrain lunar evolution models., Comment: 1 near-term proposal, 21 pages, and 6 figures

In the year 1924, a paper by Carl Wirtz appeared in Astronomische Nachrichten, entitled 'De Sitter's cosmology and the radial motion of spiral galaxies'. This paper and its author remained largely unnoticed by the community, but it seems to be the first cosmological interpretation of the redshift of galaxies as a time dilation effect and the expansion of the Universe. Edwin Hubble knew Wirtz' publications quite well. The modern reader would find Wirtz' own understanding diffuse and contradictory in some aspects, but that reflected the early literature on nebulae, to which he himself made important contributions. The 100th anniversary provides a good opportunity to present an English transcription to the community, which can be found in the appendix. This anniversary also provokes to ask for the present status of cosmology which many authors see in a crisis. From an observational viewpoint it shall be illustrated that until today there is no consistent/convincing understanding of how the Universe evolved., Comment: 9 pages, no figures accepted by Astronomische Nachrichten

The large-scale structure of the Universe and its evolution over time contains an abundance of cosmological information. One way to unlock this is by measuring the density and momentum power spectrum from the positions and peculiar velocities of galaxies, and fitting the cosmological parameters from these power spectrum. In this paper, we will explore the cross power spectrum between the density and momentum fields of galaxies. We derive the estimator of the density-momentum cross power spectrum multipoles. The growth rate of the large-scale-structure, $f\sigma_8$ is measured from fitting the combined density monopole, momentum monopole and cross dipole power spectrum. The estimators and models of power spectrum as well as our fitting method have been tested using mock catalogues, and we find that they perform well in recovering the fiducial values of the cosmological parameters of the simulations, and we also find that the errors of the parameters can be largely reduced by including the cross-power spectrum in the fit. We measure the auto-density, auto-momentum and cross power spectrum using the Sloan Digital Sky Survey Data Release 14 peculiar velocity catalogue. The fit result of the growth rate $f\sigma_8$ is $f\sigma_8=0.413^{+0.050}_{-0.058}$ at effective redshift $z_{\mathrm{eff}}=0.073$, and our measurement is consistent with the prediction of the $\Lambda$ Cold Dark Matter cosmological model assuming General Relativity., Comment: 15 pages, 8 figures, 2 tables. Publish in ApJ

The orbital period of a cataclysmic variable stands as a crucial parameter for investigating the structure and physics of these binary systems, as well as understanding their evolution. We use photometric Gaia data for dwarf novae (DNe) in the quiescent state which are available for a number of years to determine new orbital periods and improve/modify previously suggested values. Two approaches are implemented for selecting high-inclination targets, either eclipsing or with ellipsoidal variations. We determine new orbital periods for 75 DNe and improve ephemerides for 27 more (three of which change significantly), contributing 9.4% of the known DNe periods of 0.05-2.0 days, and doubling the number of known periods exceeding 0.44 days. Their phase-folded light curves are presented and arranged by orbital period, illustrating the transition from short-period systems, dominated by radiation from the accretion disc and the hot spot, to longer-period DNe, where the Roche-lobe-filling secondary star is the primary visual flux source. This transition -- which occurs around the well-known period gap (around 2-3 hours) -- is expected, as DNe with larger orbital periods typically harbour more massive donors, which contribute to the visible flux. However, this transition is not abrupt. Within the same range of periods, we observe systems dominated by ellipsoidal variations, where the companion star is clearly visible, as well as others dominated by the disc and hot spot. The presence of some DNe with ellipsoidal variations near the lower edge of the period gap is striking, as the companions in these systems are expected to be cool low-mass M-dwarfs not visible in the light curve. This could indicate that we are observing systems where the donor star was originally much more massive and underwent significant nuclear evolution before mass-transfer began, as has been suggested previously for QZ Ser., Comment: Accepted for publication in A&A, 15 pages, 3 figures

We report the discovery of a super-Earth candidate orbiting the nearby mid M dwarf Gl\,725A using the radial velocity (RV) method. The planetary signal has been independently identified using high-precision RVs from the SOPHIE and SPIRou spectrographs, in the optical and near-infrared domains, respectively. We modelled the stellar activity signal jointly with the planet using two Gaussian Processes, one for each instrument to account for the chromaticity of the stellar activity and instrumental systematics, along with a Keplerian model. The signal is significantly detected with a RV semi-amplitude of $1.67\pm0.20$ m/s. The planet Gl 725A b is found to be in an orbit compatible with circular with a period of $11.2201\pm0.0051$ days. We analysed 27 sectors of TESS photometry on which no transit event was found. We determined a minimum mass of $M_{p}\sin{i}=2.78\pm0.35\,M_{\oplus}$ which places the planet in the super-Earth regime. Using Mass-Radius relationships we predict a planetary radius to be between 1.2 and $2.0\,R_{\oplus}$. The proximity of Gl 725A, of only 3.5 pc, makes this new exoplanet one of the closest to Earth and joins the group of S-type low-mass planets in short orbits ($P<15$ d) around close M dwarfs., Comment: 26 pages, 17 figures. Accepted in A&A

The 21 cm emission from neutral hydrogen surveys holds great potential as a valuable method for exploring the large-scale structure of the Universe. In this paper, we forecast for the cross-correlation between the Thermal Sunyaev-Zel'dovich (SZ) fluctuations as probed by the Planck satellite, and fluctuations in the HI brightness temperature as probed by the ground-based Five-hundred-meter Aperture Spherical Telescope (FAST), to trace the connection between galaxy clusters and the HI large-scale structure. Assuming that the measurement is limited by instrumental noise rather than by foreground, we estimate the potential detectability of the cross-correlation signal and their improvement in the measurement of the HI cosmic density, the hydrostatic mass bias parameter, and the universal pressure profile (UPP) parameters. We obtain a constraint on the cosmic neutral hydrogen density parameter significantly to $\sigma(\Omega_{\rm HI}) = 1.0 \times 10^{-6}$. We also find that the average halo masses contributing to the ${{\rm HI}-y}$ cross-power spectrum in the one-halo regime is $\sim 1.5\times 10^{14} M_{\odot}$. Our results also show that the HI-SZ cross-correlation has great potential to probe the distribution of neutral hydrogen (HI) within halos at low redshift., Comment: 18 pages, 4 figures, 3 tables, accepted in the Astrophysical Journal

We examined in depth the star BD+00 444 (GJ 105.5, TOI-2443; V = 9.5 mag; d = 23.9 pc), with the aim of characterizing and confirming the planetary nature of its small companion, the planet candidate TOI-2443.01, which was discovered by TESS. We monitored BD+00 444 with the HARPS-N spectrograph for 1.5 years to search for planet-induced radial-velocity (RV) variations, and then analyzed the RV measurements jointly with TESS and ground-based photometry. We determined that the host is a quiet K5 V, and we revealed that the sub-Neptune BD+00 444 b has a radius of $R_b=2.36\pm0.05 R_{\oplus}$, a mass of $M_b=4.8\pm1.1 M_{\oplus}$ and, consequently, a rather low-density value of $\rho_b=2.00+0.49-0.45$ g cm-3, which makes it compatible with both an Earth-like rocky interior with a thin H-He atmosphere and a half-rocky, half-water composition with a small amount of H-He. Having an orbital period of about 15.67 days and an equilibrium temperature of about 519 K, BD+00 444 b has an estimated transmission spectroscopy metric of about 159, which makes it ideal for atmospheric follow-up with the JWST. Notably, it is the second most eccentric inner transiting planet, $e=0.302+0.051-0.035$, with a mass below 20 $M_{\oplus}$, among those with well-determined eccentricities. We estimated that tidal forces from the host star affect both planet b's rotation and eccentricity, and strong tidal dissipation may signal intense volcanic activity. Furthermore, our analysis suggests the presence of a sub-Neptune-mass planet candidate, BD+00 444 c, having an orbital period of $P=96.6\pm1.4$ days, and a minimum mass $M\sin{i}=9.3+1.8-2.0 M_{\oplus}$. With an equilibrium temperature of about 283 K, BD+00 444 c is right inside the habitable zone; however, this candidate necessitates further observations and stronger statistical evidence to be confirmed. [...], Comment: Accepted for publication in A&A on November 13 2024. 20 pages, 11 figures

Strongly lensed type Ia supernovae (SNe Ia) provide a unique cosmological probe to address the Hubble tension problem in cosmology. In addition to the sensitivity of the time delays to the value of the Hubble constant, the transient and standard candle nature of SNe Ia also enable valuable joint constraints on the model of the lens and the cosmological parameters. The upcoming Legacy Survey of Space and Time (LSST) with the Vera C. Rubin Observatory is expected to increase the number of observed SNe Ia by an order of magnitude in ten years of its lifetime. However, finding such systems in the LSST data is a challenge. In this work, we revisit the color-magnitude (CM) diagram used previously as a means to identify lensed SNe Ia and extend the work further as follows. We simulate LSST-like photometric data ($rizy$~bands) of lensed SNe Ia and analyze it in the CM parameter space. We find that a subset of lensed SNe Ia are redder compared to unlensed SNe Ia at a given magnitude, both in the rising and falling phases of their light curves and for SNe up to $z=3$. We propose a modified selection criterion based on these new results. We show that the contamination coming from the unlensed core-collapse (CC) SNe is negligible, whereas a small fraction of lensed CC SNe types Ib and Ic may get selected by this criterion as potential lensed SNe. Finally, we demonstrate that our criterion works well on a wide sample of observed unlensed SNe Ia, a handful of known multiply-imaged lensed SNe systems, and a representative sample of observed super-luminous supernovae.

We report on the onset of a coronal mass ejection (CME) using spectroscopic observations in 5303 {\AA} coronal emission line with the Visible Emission Line Coronagraph (VELC) onboard ADITYA-L1, the recently launched first Indian space solar mission. The CME was observed on 16 July 2024 in association with a X1.9 class soft X-ray flare from heliographic location S05W85. The VELC observations were near the west limb of Sun during the CME. The results obtained helped to constrain the onset time of the CME. In addition, they indicate ${\approx}$50% decrease in the coronal intensity near the source region of the CME due to mass depletion, ${\approx}$15% enhancement in the emission line width, and redshifted Doppler velocity of about ${\approx}10$ km/s. The non-thermal velocity associated with the line broadening is ${\approx}24.87$ km/s.

Low-energy cosmic rays (LECRs) play a crucial role in the formation of planetary systems, and detecting and reconstructing the properties of early LECRs is essential for understanding the mechanisms of planetary system formation. Given that LECRs interact with the surrounding medium to produce nuclear de-excitation line emissions, which are gamma-ray emissions with energy mainly within 0.1--10 MeV and are unaffected by stellar wind modulation, these emissions can accurately reflect the properties of LECRs. This study introduces an innovative method for using gamma-ray emissions to infer LECR properties. We employed the Parker transport equation to simulate the propagation and spectral evolution of LECRs in a protoplanetary disk and calculated the characteristic gamma-ray emissions resulting from interactions between LECRs and disk material. These gamma-ray emissions encapsulate the spectral information of LECRs, providing a powerful tool to reconstruct the cosmic ray environment at that time. This method, supported by further theoretical developments and observations, will fundamentally enhance our understanding of the impact of CRs on the origin and evolution of planetary systems and address significant scientific questions regarding the cosmic ray environment at the origin of life., Comment: Published by Universe. 13 pages, 3 figures, 1 table

We investigate the heating of protoplanetary disks caused by shocks associated with spiral density waves induced by an embedded planet. Using two-dimensional hydrodynamical simulations, we explore the dependence of shock heating rates on various disk and planetary parameters. Our results show that the shock heating rates are primarily influenced by the planet's mass and the disk's viscosity, while being insensitive to the thermal relaxation rate and the radial profiles of the disk's surface density and sound speed. We provide universal empirical formulas for the shock heating rates produced by the primary and secondary spiral arms as a function of orbital radius, viscosity parameter $\alpha$, and planet-to-star mass ratio $q$. The obtained formulas are accurate within a factor of a few for a moderately viscous and adiabatic disk with a planet massive enough that its spiral arms are strongly nonlinear. Using these universal relations, we show that shock heating can overwhelm viscous heating when the disk viscosity is low ($\alpha \lesssim 10^{-3}$) and the planet is massive ($q \gtrsim 10^{-3}$). Our empirical relations for the shock heating rates are simple and can be easily implemented into radially one-dimensional models of gas and dust evolution in protoplanetary disks., Comment: 13 pages, 13 figure, revised version submitted to PASJ after referee's report. Comments welcome

Planetesimal formation via the streaming and gravitational instabilities of dust in protoplanetary disks requires a local enhancement of the dust-to-gas mass ratio. Radial drift of large grains toward pressure bumps in gas disks is a plausible mechanism for achieving the required dust concentration. However, recent millimeter disk observations suggest that the maximum sizes of dust grains in these disks are considerably smaller than predicted by dust evolution models that assume sticky grains. This indicates that the grains may be more strongly coupled to the gas and hence drift more slowly than previously anticipated. In this study, we propose a new dust retention mechanism that enables an enhancement of the dust-to-gas mass ratio in disks with slowly drifting grains. This mechanism assumes that a surface accretion flow driven by magnetohydrodynamical (MHD) winds removes disk gas while retaining the slowly drifting grains below the flow. This process is expected to occur when the timescale of gas removal is shorter than the timescale of dust radial advection. To test this, we develop a radially one-dimensional framework for the transport of gas and dust in a disk with a vertically nonuniform accretion structure. Using this framework, we simulate the growth, fragmentation, and radial transport of dust grains in surface-accreting disks. Our simulations confirm a significant enhancement of the midplane dust-to-gas mass ratio when the predicted conditions for dust retention are met. Dust retention by MHD-driven surface accretion flows may thus pave the way for planetesimal formation from poorly sticky grains., Comment: 15 pages, 9 figures, revised version submitted to PASJ after referee's report. Comments welcome