Papers for Tuesday, Nov 12 2024

Recent progress with CMOS detector development has opened new parameter space for high cadence time resolved imaging of transients and fast proper motion solar system objects. Using computer simulations for a ground-based 1.23 m telescope, this research note illustrates the gain of a new generation of fast readout low noise qCMOS sensors over CCDs and makes the case for high precision monitoring of asteroid orbits that can potentially shed light on the hypothetical existence of low mass primordial black holes, as well as for other applications requiring high speed imaging.

We investigate the robustness of Neural Ratio Estimators (NREs) and Neural Posterior Estimators (NPEs) to distributional shifts in the context of measuring the abundance of dark matter subhalos using strong gravitational lensing data. While these data-driven inference frameworks can be accurate on test data from the same distribution as the training sets, in real applications, it is expected that simulated training data and true observational data will differ in their distributions. We explore the behavior of a trained NRE and trained sequential NPEs to estimate the population-level parameters of dark matter subhalos from a large sample of images of strongly lensed galaxies with test data presenting distributional shifts within and beyond the bounds of the training distribution in the nuisance parameters (e.g., the background source morphology). While our results show that NREs and NPEs perform well when tested perfectly in distribution, they exhibit significant biases when confronted with slight deviations from the examples seen in the training distribution. This indicates the necessity for caution when applying NREs and NPEs to real astrophysical data, where high-dimensional underlying distributions are not perfectly known.

The formation pathways of lenticular galaxies (S0s) in field environments remain a matter of debate. We utilize the cosmological hydrodynamic simulation, NewHorizon, to investigate the issue. We select two massive star-formation quenched S0s as our main sample. By closely tracing their physical and morphological evolution, we identify two primary formation channels: mergers and counter-rotating gas accretion. The former induces central gas inflow due to gravitational and hydrodynamic torques, triggering active central star formation which quickly depletes the gas of the galaxy. Counter-rotating gas accretion overall has a similar outcome but more exclusively through hydrodynamic collisions between the pre-existing and newly-accreted gas. Both channels lead to S0 morphology, with gas angular momentum cancellation being a crucial mechanism. These formation pathways quench star formation on a short timescale (< Gyr) compared to the timescales of environmental effects. We also discuss how counter-rotating gas accretion may explain the origin of S0s with ongoing star formation and the frequently observed gas-star misaligned kinematics in S0s.

We measured the harmonic-space power spectrum of galaxy clustering auto-correlation from the Evolutionary Map of the Universe Pilot Survey 1 data (EMU PS1) and its cross-correlation with the lensing convergence map of cosmic microwave background (CMB) from Planck Public Release 4 at the linear scale range from $\ell=2$ to 500. We applied two flux density cuts at $0.18$ and $0.4$mJy on the radio galaxies observed at 944MHz and considered two source detection algorithms. We found the auto-correlation measurements from the two algorithms at the 0.18mJy cut to deviate for $\ell\gtrsim250$ due to the different criteria assumed on the source detection and decided to ignore data above this scale. We report a cross-correlation detection of EMU PS1 with CMB lensing at $\sim$5.5$\sigma$, irrespective of flux density cut. In our theoretical modelling we considered two redshift distribution simulation models that yield consistent results, a linear and a non-linear matter power spectrum, and two linear galaxy bias models. That is a constant redshift-independent galaxy bias $b(z)=b_g$ and a constant amplitude galaxy bias $b(z)=b_g/D(z)$. By fixing a cosmology model and considering a non-linear matter power spectrum, we measured a constant galaxy bias at $0.18$mJy ($0.4$mJy) with $b_g=2.32^{+0.41}_{-0.33}$ ($2.18^{+0.17}_{-0.25}$) and a constant amplitude bias with $b_g=1.72^{+0.31}_{-0.21}$ ($1.78^{+0.22}_{-0.15}$). When $\sigma_8$ is a free parameter for the same models at $0.18$mJy ($0.4$mJy) with the constant model we found $\sigma_8=0.68^{+0.16}_{-0.14}$ ($0.82\pm0.10$), while with the constant amplitude model we measured $\sigma_8=0.61^{+0.18}_{-0.20}$ ($0.78^{+0.11}_{-0.09}$), respectively. Our results agree at $1\sigma$ with the measurements from Planck CMB and the weak lensing surveys and also show the potential of cosmology studies with future radio continuum survey data.

Direct imaging observations are biased towards wide-separation, massive companions that have degenerate formation histories. Although the majority of exoplanets are expected to form via core accretion, most directly imaged exoplanets have not been convincingly demonstrated to follow this formation pathway. We obtained new interferometric observations of the directly imaged giant planet AF Lep b with the VLTI/GRAVITY instrument. We present three epochs of 50$\mu$as relative astrometry and the K-band spectrum of the planet for the first time at a resolution of R=500. Using only these measurements, spanning less than two months, and the Hipparcos-Gaia Catalogue of Accelerations, we are able to significantly constrain the planet's orbit; this bodes well for interferometric observations of planets discovered by Gaia DR4. Including all available measurements of the planet, we infer an effectively circular orbit ($e<0.02, 0.07, 0.13$ at $1, 2, 3 \sigma$) in spin-orbit alignment with the host, and a measure a dynamical mass of $M_\mathrm{p}=3.75\pm0.5\,M_\mathrm{Jup}$. Models of the spectrum of the planet show that it is metal rich ([M/H]$=0.75\pm0.25$), with a C/O ratio encompassing the solar value. This ensemble of results show that the planet is consistent with core accretion formation.

SwJ023017.0+283603 (SwJ0230) exhibited soft X-ray (0.3-1.0 keV) eruptions recurring roughly every 22 days. We present results from an extended monitoring campaign of SwJ0230 using Swift, NICER, and deep XMM-Newton observations. Our main findings are: 1) SwJ0230 did not display any eruptions during two 80-day periods (June-September 2023 and July-September 2024) of high-cadence monitoring with NICER and Swift, suggesting that the eruptions have ceased, implying an eruption lifetime of less than 536 days; 2) quiescent/non-eruption emission is detected with XMM-Newton, with a 0.3-2.0 keV luminosity of 4$\times$10$^{40}$ erg/s (bolometric luminosity of $<$0.1% Eddington assuming a black hole mass of 10$^{6-7}$ M$_{\odot}$), that is consistent with a thermal disk spectrum peaking at 0.11$^{+0.06}_{-0.03}$ keV; 3) SwJ0230 exhibited multiple, rapid eruptions (duration$<$5 hours, similar to quasi-periodic eruptions; QPEs), and there is tentative evidence that they recur, on average, on roughly the same timescale of 22 days. \target therefore exhibited (when active) both rapid, QPE-like outbursts and longer-duration outbursts, more akin to those from repeating partial Tidal Disruption Event (rpTDE) candidates. These findings are difficult to explain with existing models that invoke an orbiter interacting with a persistent disk and those involving disk instabilities. We propose a hybrid model wherein an object of smaller mass (e.g., a Jupiter-sized planet) being repeatedly partially stripped and subsequently punching through its own, fallback-induced disk, can explain many of the observed properties, including the long-duration flares (from accretion), the short-duration outbursts (from the planet-disk interaction), and the turn-off of the flares (when the planet is totally stripped of gas).

The motion of planetesimals was studied in the Proxima Centauri and TRAPPIST 1 exoplanetary systems. The size of the feeding zone of planet Proxima Centauri c is discussed. It was noted that after hundreds of Myrs, some planetesimals could still move in elliptical resonant orbits inside the feeding zone of this planet that had been mainly cleared from planetesimals. The probability of a collision of a planetesimal initially located in the feeding zone of planet c with inner planet b was obtained to be about 0.0002 and 0.001 at initial eccentricity of orbits of planetesimals equal to 0.02 or 0.15, respectively. A lot of icy material and volatiles could be delivered from the icy zone near the orbit of planet c to inner planets b and d. The inclinations of orbits of 80% of the planetesimals that moved between 500 or 1200 AU from the star did not exceed 10o. It was obtained that several planets in the TRAPPIST-1 system accumulated planetesimals initially located at the same distance. Outer layers of neighbouring TRAPPIST-1 planets can include similar material.

Data compression techniques focused on information preservation have become essential in the modern era of big data. In this work, an encoder-decoder architecture has been designed, where adversarial training, a modification of the traditional autoencoder, is used in the context of astrophysical spectral analysis. The goal of this proposal is to obtain an intermediate representation of the astronomical stellar spectra, in which the contribution to the flux of a star due to the most influential physical properties (its surface temperature and gravity) disappears and the variance reflects only the effect of the chemical composition over the spectrum. A scheme of deep learning is used with the aim of unraveling in the latent space the desired parameters of the rest of the information contained in the data. This work proposes a version of adversarial training that makes use of a discriminator per parameter to be disentangled, thus avoiding the exponential combination that occurs in the use of a single discriminator, as a result of the discretization of the values to be untangled. To test the effectiveness of the method, synthetic astronomical data are used from the APOGEE and Gaia surveys. In conjunction with the work presented, we also provide a disentangling framework (GANDALF) available to the community, which allows the replication, visualization, and extension of the method to domains of any nature.

This study analyzes the motion of bodies ejected from the Earth or the Moon. We studied the ejection of bodies from several points on the Earth's surface, as well as from the most far point of the Moon from the Sun. Different velocities and angles of ejection of bodies were considered. The dynamical lifetimes of bodies reached a few hundred million years. Over the entire considered time interval, the values of the probability of a collision of a body ejected from the Earth with the Earth were approximately 0.3, 0.2, and 0.15-0.2 at an ejection velocity vej equaled to 11.5, 12, and 14 km/s, respectively. At vej<11.3 km/s, most of the ejected bodies fell back onto the Earth. The total number of bodies delivered to the Earth and Venus probably did not differ much. The probabilities of collisions of bodies with Mercury and Mars usually did not exceed 0.1 and 0.02, respectively. At vej>11.5 km/s, the probability of a collision of a body ejected from the Earth with the Moon was about 15-35 times less than that with the Earth, and it was about 0.01. The probability of a collision with the Earth for a body ejected from the Moon moving in its present orbit was about 0.3-0.32, 0.2-0.22, and 0.1-0.14 at vej=2.5 km/s, vej=5 km/s, and at 12<vej<16.4 km/s, respectively.

We consider a modified gravity model with a running gravitational constant coupled to a varying dark energy fluid and test its imprint on the growth of structure in the universe. Using Redshift Space Distortion (RSD) measurement results, we show a tension at the $3 \sigma$ level between the best fit $\Lambda$CDM and the corresponding parameters obtained from the Planck data. Unlike many modified gravity-based solutions that overlook scale dependence and model-specific background evolution, we study this problem in the broadest possible context by incorporating both factors into our investigation. We performed a full perturbation analysis to demonstrate a scale dependence in the growth equation. Fixing the scale to $k = 0.1 h$ Mpc$^{-1}$ and introducing a phenomenological functional form for the varying Newton coupling $G$ with only one free parameter, we conduct a likelihood analysis of the RSD selected data. The analysis reveals that the model can bring the tension level within $1 \sigma$ while maintaining the deviation of $G$ from Newton's gravitational constant at the fifth order.

Transitional millisecond pulsars (tMSPs) are neutron-star systems that alternate between a rotation-powered radio millisecond pulsar state and an accretion-disk-dominated low-mass X-ray binary (LMXB)-like state on multi-year timescales. During the LMXB-like state, the X-ray emission from tMSPs switches between "low" and "high" X-ray brightness modes on a timescale of seconds to minutes (or longer), while the radio emission shows variability on timescales of roughly minutes. Coordinated VLA and Chandra observations of the nearby tMSP PSR J1023+0038 uncovered a clear anti-correlation between radio and X-ray luminosities such that the radio emission consistently peaks during the X-ray low modes. In addition, there are sometimes also radio/X-ray flares that show no obvious correlation. In this paper, we present simultaneous radio and X-ray observations of a promising tMSP candidate system, 3FGL J1544.6-1125, which shows optical, gamma-ray, and X-ray phenomena similar to PSR J1023+0038, but which is challenging to study because of its greater distance. Using simultaneous VLA and Chandra observations we find that the radio and X-ray emission are consistent with being anti-correlated in a manner similar to PSR J1023+0038. We discuss how our results help in understanding the origin of bright radio emission from tMSPs. The greater sensitivity of upcoming telescopes like the Square Kilometre Array will be crucial for studying the correlated radio/X-ray phenomena of tMSP systems.

From CMB polarization data alone we reconstruct the CMB lensing power spectrum, comparable in overall constraining power to previous temperature-based reconstructions, and an unlensed E-mode power spectrum. The observations, taken in 2019 and 2020 with the South Pole Telescope (SPT) and the SPT-3G camera, cover 1500 deg$^2$ at 95, 150, and 220 GHz with arcminute resolution and roughly 4.9$\mu$K-arcmin coadded noise in polarization. The power spectrum estimates, together with systematic parameter estimates and a joint covariance matrix, follow from a Bayesian analysis using the Marginal Unbiased Score Expansion (MUSE) method. The E-mode spectrum at $\ell>2000$ and lensing spectrum at $L>350$ are the most precise to date. Assuming the $\Lambda$CDM model, and using only these SPT data and priors on $\tau$ and absolute calibration from Planck, we find $H_0=66.81\pm0.81$ km/s/Mpc, comparable in precision to the Planck determination and in 5.4$\sigma$ tension with the most precise $H_0$ inference derived via the distance ladder. We also find $S_8=0.850\pm0.017$, providing further independent evidence of a slight tension with low-redshift structure probes. The $\Lambda$CDM model provides a good simultaneous fit to the combined Planck, ACT, and SPT data, and thus passes a powerful test. Combining these CMB datasets with BAO observations, we find that the effective number of neutrino species, spatial curvature, and primordial helium fraction are consistent with standard model values, and that the 95% confidence upper limit on the neutrino mass sum is 0.075 eV. The SPT data are consistent with the somewhat weak preference for excess lensing power seen in Planck and ACT data relative to predictions of the $\Lambda$CDM model. We also detect at greater than 3$\sigma$ the influence of non-linear evolution in the CMB lensing power spectrum and discuss it in the context of the $S_8$ tension.(abridged)

Brown dwarfs with measured dynamical masses and spectra from direct imaging are benchmarks that anchor substellar atmosphere cooling and evolution models. We present Subaru SCExAO/CHARIS infrared spectroscopy of HIP 93398 B, a brown dwarf companion recently discovered by Li et al. 2023 as part of an informed survey using the Hipparcos-Gaia Catalog of Accelerations. This object was previously classified as a T6 dwarf based on its luminosity, with its independently-derived age and dynamical mass in tension with existing models of brown dwarf evolution. Spectral typing via empirical standard spectra, temperatures derived by fitting substellar atmosphere models, and J-H, J-K and H-L' colors all suggest that this object has a substantially higher temperature and luminosity, consistent with classification as a late-L dwarf near the L/T transition (T = 1200$^{+140}_{-119}$ K) with moderate to thick clouds possibly present in its atmosphere. When compared with the latest generation of evolution models that account for clouds with our revised luminosity and temperature for the object, the tension between the model-independent mass/age and model predictions is resolved.

We estimate the one-loop perturbation kernels for a minimal modified gravity model in which dark energy is coupled to dark mater via a constant coupling. We derive the time-dependent kernels via analytical and numerical solutions and provide accurate fitting functions. These kernels can be directly employed to test for modified gravity in forthcoming large-scale surveys.

With Gaia, APOGEE, GALAH, and LAMOST data, we investigate the positional, kinematic, chemical, and age properties of nine moving groups in the solar neighborhood. We find that each moving group has a distinct distribution in the velocity space in terms of its metallicity, $\alpha$ abundance, and age. Comparison of the moving groups with their underlying background stars suggests that they have experienced the enhanced, prolonged star formation. We infer that any dynamical effects that gathered stars as a moving group in the velocity space also worked for gas. We propose for the first time that the ensuing newborn stars from such gas inherited the kinematic feature from the gas, shaping the current stellar velocity distributions of the groups. Our findings improve the understanding of the origins and evolutionary histories of moving groups in the solar neighborhood.

Context. A series of studies have demonstrated that the Gaia multipeak method (GMP) is a very efficient technique to select active galactic nucleus (AGN) pair candidates. The number of candidates is determined by the size of the input AGN catalogs, usually limited to spectroscopically-confirmed objects. Aims. The objective of this work is to compile a larger and highly reliable catalog of GMP pair candidates extracted from the six million objects the Gaia AGN catalog, the majority of which lack spectroscopic information. Methods. In order to ascertain the differences in the properties of GMP pair candidates compared to normal AGN, we conducted an investigation utilising samples of GMP AGN. These differences were employed to establish the optimal selecting criteria, which ultimately led to the identification of a highly reliable candidate catalog. Results. We found significant differences in astrometry and multi-band colour distribution between normal AGN and GMP pair candidates. A DUal and Lensed AGN candidate catalog with GMP method (DULAG) comprising 5,286 sources was ultimately compiled, accompanied by a highly reliable Golden sample of 1,867 sources. A total of 37 sources in the Golden sample have been identified as dual AGN or lensed AGN. For the majority of sources in the Golden sample, we provide reference redshifts and find three close AGN pair candidates among them.

(Abridged) JWST continues to deliver incredibly detailed infrared (IR) images of star forming regions in the Milky Way and beyond. IR emission from star-forming regions is very spectrally rich due to emission from gas-phase atoms, ions, and polycyclic aromatic hydrocarbons (PAHs). Physically interpreting IR images of these regions relies on assumptions about the underlying spectral energy distribution in the imaging bandpasses. We aim to provide empirical prescriptions linking line, PAH, and continuum intensities from JWST images, to facilitate the interpretation of JWST images in a wide variety of contexts. We use JWST PDRs4All Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) imaging and Near-Infrared Spectrograph (NIRSpec) integral field unit (IFU) and MIRI Medium Resolution Spectrograph (MRS) spectroscopic observations of the Orion Bar photodissociation region (PDR), to directly compare and cross-calibrate imaging and IFU data at ~100 AU resolution over a region where the radiation field and ISM environment evolves from the hot ionized gas to the cold molecular gas. We measure the relative contributions of line, PAH, and continuum emission to the NIRCam and MIRI filters as functions of local physical conditions. We provide empirical prescriptions based on NIRCam and MIRI images to derive intensities of emission lines and PAH features. Within the range of the environments probed in this study, these prescriptions accurately predict Pa-alpha, Br-alpha, PAH 3.3 um and 11.2 um intensities, while those for FeII 1.644 um, H_2 1--0 S(1) 2.12 um and 1--0 S(9) 4.96 um, and PAH 7.7 um show more complicated environmental dependencies. Linear combinations of JWST NIRCam and MIRI images provide effective tracers of ionized gas, H_2, and PAH emission in PDRs. We expect these recipes to be useful for both the Galactic and extragalactic communities.

Context. Cosmic dust is ubiquitous in astrophysical environments, where it significantly influences the chemistry and the spectra. Dust grains are likely to grow through the accretion of atoms and molecules from the gas-phase onto them. Despite their importance, only a few studies compute sticking coefficients for relevant temperatures and species, and their direct impact on grain growth. Overall, the formation of dust and its growth are processes not well understood. Aims. To calculate sticking coefficients, binding energies, and grain growth rates over a wide range of temperatures, for various gas species interacting with carbonaceous dust grains. Methods. We perform molecular dynamics simulations with a reactive force field algorithm to compute accurate sticking coefficients and obtain binding energies. The results are included in an astrophysical model of nucleation regions to study dust growth. Results. We present, for the first time, sticking coefficients of H, H2, C, O, and CO on amorphous carbon structures for temperatures ranging from 50 K to 2250 K. In addition, we estimate the binding energies of H, C, and O in carbonaceous dust to calculate the thermal desorption rates. Combining accretion and desorption allows us to determine an effective accretion rate and sublimation temperature for carbonaceous dust. Conclusions. We find that sticking coefficients can differ substantially from what is commonly used in astrophysical models and this gives new insight on carbonaceous dust grain growth via accretion in dust-forming regions.

We present results from the first application of the Global Navigation Satellite System (GNSS; GPS is one example of a collection of satellites in GNSS) for radio beam calibration using a commercial GNSS receiver with the Deep Dish Development Array (D3A) at the Dominion Radio Astrophysical Observatory (DRAO). Several GNSS satellites pass through the main and side lobes of the beam each day, enabling efficient mapping of the 2D beam structure. Due to the high SNR and abundance of GNSS satellites, we find evidence that GNSS can probe several side lobes of the beam through repeatable measurements of the beam over several days. Over three days of measurements, we find a measured difference reaching a minimum of 0.56 db-Hz in the main lobe of the primary beam. These results show promise for the use of GNSS in beam mapping for the Canadian Hydrogen Observatory and Radio-transient Detector (CHORD) and other future "large-N" radio interferometers. They also motivate future development of the technique within radio astronomy.

Direct imaging (DI) campaigns are uniquely suited to probing the outer regions around young stars and looking for giant exoplanet and brown dwarf companions, hence providing key complementary information to radial velocity (RV) and transit searches for the purpose of demographic studies. However, the critical 5-20 au region, where most giant planets are thought to form, remains poorly explored, lying in-between RV and DI capabilities. Significant gains in detection performances can be attained at no instrumental cost by means of advanced post-processing techniques. In the context of the COBREX project, we have assembled the largest collection of archival DI observations to date in order to undertake a large and uniform re-analysis. In particular, this paper details the re-analysis of 400 stars from the GPIES survey operated at GPI@Gemini South. Following the pre-reduction of raw frames, GPI data cubes were processed by means of the PACO algorithm. Candidates were identified and vetted based on multi-epoch proper motion analysis -- whenever possible -- and by means of a suitable color-magnitude diagram. The conversion of detection limits into detectability maps allowed for an estimate of unbiased occurrence frequencies of giant planets and brown dwarfs. Deeper detection limits were derived compared to the literature, with up to a twofold gain in minimum detectable mass compared to previous GPI-based publications. Although no new substellar companion was confirmed, we identified two interesting planet candidates awaiting follow-up observations. We derive an occurrence rate of $1.7_{-0.7}^{+0.9}\%$ for $5$~\mjup$ < m < 13$~\mjup planets in $10~\text{au}< a < 100~\text{au}$, that raises to $2.2_{-0.8}^{+1.0}\%$ when including substellar objects up to 80 \mjup.(abridged)

The reheating temperature plays a crucial role in the early universe's evolution, marking the transition from inflation to the radiation-dominated era. It directly impacts the number of $e$-folds and, consequently, the observable parameters of inflation, such as the spectral index of scalar perturbations. By establishing a relationship between the gravitational reheating temperature and the spectral index, we can derive constraints on inflationary models. Specifically, the range of viable reheating temperatures imposes bounds on the spectral index, which can then be compared with observational data, such as those from the Planck satellite, to test the consistency of various models with cosmological observations. Additionally, in the context of dark matter production, we demonstrate that gravitational reheating provides a viable mechanism when there is a relationship between the mass of the dark matter particles and the mass of the particles responsible for reheating. This connection offers a pathway to link dark matter genesis with inflationary and reheating parameters, allowing for a unified perspective on early universe dynamics.

While binary merger events have been an active area of study in both simulations and observational work, the formation channels by which a high-mass star extends from Roche lobe overflow (RLO) in a decaying orbit of a black-hole (BH) companion to a binary black-hole (BBH) system merits further investigation. Variable length-scales must be employed to accurately represent the dynamical fluid transfer and morphological development of the primary star as it conforms to a diminishing Roche lobe under the runaway influence of the proximal BH. We have simulated and evolved binary mass flow under these conditions to better identify the key transitional processes from RLO to BBHs. We demonstrate a new methodology to model RLO systems to unprecedented resolution simultaneously across the envelope, donor wind, tidal stream, and accretion disk regimes without reliance upon previously universal symmetry, mass flux, and angular momentum flux assumptions. We have applied this method to the semidetached high-mass X-ray binary M33 X-7 in order to provide a direct comparison to recent observations of an RLO candidate system at two overflow states of overfilling factors f = 1.01 and f = 1.1. We found extreme overflow (f = 1.1) to be entirely conservative in both mass and angular momentum transport, forming a conical L1 tidal stream of density and deflected angle comparable to existing predictions. This case lies within the unstable mass transfer (MT) regime as recently proposed of M33 X-7. The f = 1.01 case differed in stream geometry, accretion disk size, and efficiency, demonstrating nonconservative stable MT through a ballistic uniform-width stream. The nonconservative and stable nature of the f = 1.01 case MT also suggests that existing assumptions of semidetached binaries undergoing RLO may mischaracterize their role and distribution as progenitors of BBHs and common envelopes.

We used the Condor Array Telescope to obtain deep imaging observations through the luminance broad-band and He II 468.6 nm, [O III] 500.7 nm, He I 587.5 nm, H$\alpha$, [N II] 658.4 nm, and [S II] 671.6 nm narrow-band filters of an extended region comprising 13 "Condor fields" spanning $\approx 8 \times 8$ deg$^2$ on the sky centered near M81 and M82. Here we describe the acquisition and processing of these observations, which together constitute unique very deep imaging observations of a large portion of the M81 Group through a complement of broad- and narrow-band filters. The images are characterized by an intricate web of faint, diffuse, continuum produced by starlight scattered from Galactic cirrus, and all prominent cirrus features identified in the broad-band image can also be identified in the narrow-band images. We subtracted the luminance image from the narrow-band images to leave more or less only line emission in the difference images, and we masked regions of the resulting images around stars at an isophotal limit. The difference images exhibit extensive extended structures of ionized gas in the direction of the M81 Group, from known galaxies of the M81 Group, clouds of gas, filamentary structures, and apparent or possible bubbles or shells. Specifically, the difference images show a remarkable filament known as the "Ursa Major Arc;" a remarkable network of criss-crossed filaments between M81 and NGC 2976, some of which intersect and overlap the Ursa Major Arc; and details of a "giant shell of ionized gas."

We used the Condor Array Telescope to obtain deep imaging observations through luminance broad-band and He II, [O III], He I, H$\alpha$, [N II], and [S II] narrow-band filters of an extended region of the M81 Group spanning $\approx 8 \times 8$ deg$^2$ on the sky centered near M81 and M82. Here we report aspects of these observations that are specifically related to (1) a remarkable filament known as the "Ursa Major Arc" that stretches $\approx 30$ deg on the sky roughly in the direction of Ursa Major, (2) a "Giant Shell of Ionized Gas" that stretches $\approx 0.8$ deg on the sky located $\approx 0.6$ deg NW of M82, and (3) a remarkable network of ionized gaseous filaments revealed by the new Condor observations that appear to connect the arc, the shell, and various of the galaxies of the M81 Group and, by extension, the group itself. We measure flux ratios between the various ions to help to distinguish photoionized from shock-ionized gas, and we find that the flux ratios of the arc and shell are not indicative of shock ionization. This provides strong evidence against a previous interpretation of the arc as an interstellar shock produced by an unrecognized supernova. We suggest that all of these objects, including the arc, are associated with the M81 Group and are located at roughly the distance $\approx 3.6$ Mpc of M81, that the arc is an intergalactic filament, and that the objects are associated with the low-redshift cosmic web.

Bubbles and super-bubbles are ubiquitous in the interstellar medium and influence their local magnetic field. Starting from the assumption that bubbles result from violent explosions that sweep matter away in a thick shell, we derive the analytical equations for the divergence-free magnetic field in the shell. The explosion velocity field is assumed to be radial but not necessarily spherical, making it possible to model various-shaped bubbles. Assuming an explosion center, the magnetic field at the present time is fully determined by the initial uniform magnetic field, the present-time geometry of the bubble shell, and a radial vector field that encodes the explosion-induced displacement of matter, from its original location to its present-time location. We present the main characteristics of our magnetic-field model using a simple displacement model which predicts a constant density of the swept-up matter in the bubble shell and magnetic flux conservation. We further estimate the expected contribution of the shell of the Local Bubble, the super-bubbles in which the Sun resides, to the integrated Faraday rotation measures and synchrotron emission and compare these to full-sky observational data. We find that, while the contribution to the former is minimal, the contribution to the latter is very significant at Galactic latitudes $|b|>45^\circ$. Our results underline the need to take the Local Bubble into account in large-scale Galactic magnetic field studies.

Coronal Mass Ejections (CMEs) erupting from the host star are expected to have effects on the atmospheric erosion processes of the orbiting planets. For planets with a magnetosphere, the embedded magnetic field in the CMEs is thought to be the most important parameter to affect planetary mass loss. In this work, we investigate the effect of different magnetic field structures of stellar CMEs on the atmosphere of a hot Jupiter with a dipolar magnetosphere. We use a time-dependent 3D radiative magnetohydrodynamics (MHD) atmospheric escape model that self-consistently models the outflow from hot Jupiters magnetosphere and its interaction with stellar CMEs. For our study, we consider three configurations of magnetic field embedded in stellar CMEs -- (a) northward $B_z$ component, (b) southward $B_z$ component, and (c) radial component. {We find that both the CMEs with northward $B_z$ component and southward $B_z$ component increase the planetary mass-loss rate when the CME arrives from the stellar side, with the mass-loss rate remaining higher for the CME with northward $B_z$ component until it arrives at the opposite side.} The largest magnetopause is found for the CME with a southward $B_z$ component when the dipole and the CME magnetic field have the same direction. We also find that during the passage of a CME, the planetary magnetosphere goes through three distinct changes - (1) compressed magnetosphere, (2) enlarged magnetosphere, and (3) relaxed magnetosphere for all three considered CME configurations. We compute synthetic Ly-$\alpha$ transits at different times during the passage of the CMEs. The synthetic Ly-$\alpha$ transit absorption generally increases when the CME is in interaction with the planet for all three magnetic configurations. The maximum Ly-$\alpha$ absorption is found for the radial CME case when the magnetosphere is the most compressed.

We present 22 GHz imaging of regions of massive star formation within the Local Wolf-Rayet Galaxy Sample (LWRGS), a NSF's Karl G. Jansky Very Large Array (VLA) survey of 30 local galaxies showing spectral features of Wolf-Rayet (WR) stars. These spectral features are present in galaxies with young super star clusters (SSCs), and are an indicator of large concentrations of massive stars. We present a catalog of 92 individually-identified regions of likely free-free emission associated with potential young SSCs located in these WR galaxies. The free-free fluxes from these maps allow extinction-free estimates of the Lyman continuum rates, masses, and luminosities of the emission regions. 39 of these regions meet the minimum Lyman continuum rate to contain at least once SSC, and 29 of these regions could contain individual SSCs massive enough to test specific theories on star formation and feedback inhibition in SSCs, requiring follow-up observations at higher spatial resolution. The resulting catalog provides sources for future molecular line and infrared studies into the properties of super star cluster formation.

Brown dwarfs form the key, yet poorly understood, link between stellar and planetary astrophysics. These objects offer unique tests of Galactic structure, but observational limitations have inhibited the large-scale analysis of these objects to date. Major upcoming sky surveys will reveal unprecedented numbers of brown dwarfs, among even greater numbers of stellar objects, enabling the statistical study of brown dwarfs. To extract the comparatively rare brown dwarfs from these massive datasets, we must understand how they will look in upcoming surveys. In this work, we construct a synthetic population of brown dwarfs in the Solar Neighborhood to explore their evolutionary properties using Gaia-derived star formation histories alongside observational mass, metallicity, and age relationships. We apply the cloudless Sonora Bobcat, hybrid SM08, and gravity-dependent hybrid Sonora Diamondback evolutionary models to the sample. We present the simulated luminosity function and its evolution with distance from the Galactic Plane. Our simulation shows that brown dwarf population statistics are a function of height above/below the Galactic Plane and sample different age distributions. Interpreting the local sample requires combining evolutionary models, the initial mass function, the star formation history, and kinematic heating. Our models are a guide to how well height-dependent samples can test these scenarios. Sub-populations of brown dwarfs farther from the Plane are older and occupy a different region of brown dwarf parameter space than younger sub-populations closer to the Galactic Plane. Therefore, fully exploring population statistics both near and far from the Plane is critical to prepare for upcoming surveys.

The cosmic curvature $\Omega_{K}$ is an important parameter related to the inflationary cosmology and the ultimate fate of the universe. In this work, we adopt the non-CMB observations to constrain $\Omega_{K}$ in the $\Lambda$CDM model and its extensions. The DESI baryon acoustic oscillation, DES type Ia supernova, cosmic chronometer, and strong gravitational lensing time delay data are considered. We find that the data combination favors an open universe in the $\Lambda$CDM model, specifically $\Omega_{K}=0.108\pm0.056$ at the $1\sigma$ confidence level, which is in $2.6\sigma$ tension with the Planck CMB result supporting our universe being slightly closed. In the $\Lambda$CDM extensions, the data combination is consistent with a spatially flat universe. However, the central value of $\Omega_{K}$ is positive and has a significant deviation from zero. We adopt the Akaike information criterion to compare different cosmological models. The result shows that non-flat models fit the observational data better that the flat $\Lambda$CDM model, which adds evidence to the argument that flat $\Lambda$CDM is not the ultimate model of cosmology.

Studying the periodic flux-variation behavior of blazars is vital for probing supermassive black hole binaries and the kinematics of relativistic jets. In this work, we report the detection of the multi-band possible periodic variations of the blazar PKS J2134-0153, including the infrared ($1.6(\pm0.4)\times 10^3$ days) and optical ($1.8(\pm1)\times 10^3$ days). The periods in the infrared and optical bands are statistically consistent with the period in the radio band ($P_{\mathrm{Radio}}$$ = 1760\pm33$ days, obtained from our previous work). Moreover, flux variations in different bands are correlated with evident inter-band time delays, and the time lags of infrared and optical emission with respect to radio emission are $(3.3\pm2.3)\times10^{2}$ days and $(3.0\pm2.3)\times10^{2}$ days, respectively. The cross-correlations indicate a common origin of radio, infrared, and optical emission. The relative positions between emission regions of infrared and optical emission to radio emission are estimated according to the time lags, i.e., $0.37\pm0.26$ pc and $0.33\pm0.26$ pc. The relative distances seem to be quantitatively consistent with the theoretical prediction.

Using the MOCCA code, we study the evolution of globular clusters with multiple stellar populations. For this purpose, the MOCCA code has been significantly extended to take into account the formation of an enriched population of stars from re-accreted gas with a time delay after the formation of the pristine population of stars. The possibility of cluster migration in the host galaxy and the fact that the pristine population can be described by a model, not in virial equilibrium are also taken into account. Gas re-accretion and cluster migration have a decisive impact on the observational parameters of clusters and the ratio of the number of objects between the pristine and enriched populations. The obtained results, together with observational data, suggest a speculative scenario that makes it possible to explain observational data, the correlation between the mass of the cluster and the ratio of the pristine to the enriched populations, and the observational fact that for some globular clusters, the pristine population is more concentrated than the enriched one. In this scenario, it is important to take into account the environment in which the cluster lives, the conditions in the galaxy when it formed, and the fact that a significant part of the globular clusters associated with the Galaxy come from dwarf galaxies that merged with the Milky Way. The initial conditions describing GCs in the simulations discussed in the paper are different from typical initial GC models that are widely used. Instead of GCs being highly concentrated and lying deep inside the Roche lobe, models that fill the Roche lobe are required. This carries strong constraints on where in the galaxy GCs are formed.

Recovering impact parameter variations in multi-planet systems is an effective approach for detecting non-transiting planets and refining planetary mass estimates. Traditionally, two methodologies have been employed: the Individual Fit, which fits each transit independently to analyze impact parameter changes, and the Dynamical Fit, which simulates planetary dynamics to match transit light curves. We introduce a new fitting method, Simultaneous Impact Parameter Variation Analysis (SIPVA), which outperforms the Individual Fit and is computationally more efficient than the Dynamical Fit. SIPVA directly integrates a linear time-dependent model for impact parameters into the Monte Carlo Markov Chain (MCMC) algorithm by fitting all transits simultaneously. We evaluate SIPVA and the Individual Fit on artificial systems with varying LLRs and find that SIPVA consistently outperforms the Individual Fit in recovery rates and accuracy. When applied to selected Kepler planetary candidates exhibiting significant transit duration variations (TDVs), SIPVA identifies significant impact parameter trends in 10 out of 16 planets. In contrast, the Individual Fit does so in only 4. We also employ probabilistic modeling to calculate the theoretical distribution of planets with significant impact parameter variations across all observed Kepler systems and compare the distribution of recovered candidates by the Individual Fit and Dynamical Fit from previous work with our theoretical distribution. Our findings offer an alternative framework for analyzing planetary transits, relying solely on Bayesian inference without requiring prior assumptions about the planetary system's dynamical architecture.

Massive, intensely star-forming galaxies at high redshift require a supply of molecular gas from their gas reservoirs, replenished by infall from the surrounding circumgalactic medium, to sustain their immense star-formation rates. However, our knowledge of the extent and morphology of their cold-gas reservoirs is still in its infancy. We present the results of stacking 80 hours of JVLA observations of CO(1--0) emission -- which traces the cold molecular gas -- in 19 $z=2.0-4.5$ dusty, star-forming galaxies from the AS2VLA survey. The visibility-plane stack reveals extended emission with a half-light radius of $3.8\pm0.5$~kpc, 2--3$\times$ more extended than the dust-obscured star formation and $1.4\pm0.2\times$ more extended than the stellar emission. Similarly, stacking the [CI](1--0) observations for a subsample of our galaxies yields sizes consistent with CO(1--0). The CO(1--0) size is comparable to the [CII] halos detected around high-redshift star-forming this http URL bulk (up to 80\%) of molecular gas resides outside the star-forming region; only a small part of their molecular gas reservoir directly contributes to their current star formation. Photon-dissociation region modelling indicates that the extended CO(1--0) emission arises from clumpy, dense clouds rather than smooth, diffuse gas.

JWST/MIRI images have been used to study the Fourier transform power spectra (PS) of two spiral galaxies, NGC 628 and NGC 5236, and two dwarfs, NGC 4449 and NGC 5068, at distances ranging from 4 to 10 Mpc. The PS slopes on scales larger than 200 pc range from -0.6 at 21 microns to -1.2 at 5.6 microns, suggesting a scaling of region luminosity with size as a power law with index ranging from 2.6 to 3.2, respectively. This result is consistent with the size-luminosity relation of star-forming regions found elsewhere, but extending here to larger scales. There is no evidence for a kink or steepening of the PS at some transition from two-dimensional to three-dimensional turbulence on the scale of the disk thickness. This lack of a kink could be from large positional variations in the PS depending on two opposite effects: local bright sources that make the slope shallower and exponential galaxy profiles that make the slope steeper. The sources could also be confined to a layer of molecular clouds that is thinner than the HI or cool dust layers where PS kinks have been observed before. If the star formation layers observed in the near-infrared here are too thin, then the PS kink could be hidden in the broad tail of the JWST point spread function.

In this second paper on the DECam deep drilling field (DDF) program we release 2,020 optical gri-band light curves for transients and variables in the extragalactic COSMOS and ELAIS fields based on time series observations with a 3-day cadence from semester 2021A through 2023A. In order to demonstrate the wide variety of time domain events detected by the program and encourage others to use the data set, we characterize the sample by presenting a brief analysis of the light curve parameters such as time span, amplitude, and peak brightness. We also present preliminary light curve categorizations, and identify potential stellar variables, active galactic nuclei, tidal disruption events, supernovae (such as Type Ia, Type IIP, superluminous, and gravitationally lensed supernovae), and fast transients. Where relevant, the number of identified transients is compared to the predictions of the original proposal. We also discuss the challenges of analyzing DDF data in the context of the upcoming Vera C. Rubin Observatory and its Legacy Survey of Space and Time, which will include DDFs. Images from the DECam DDF program are available without proprietary period and the light curves presented in this work are publicly available for analysis.

The intense magnetic fields of neutron stars naturally lead to strong anisotropy and polarization of radiation emanating from their surfaces, both being sensitive to the hot spot position on the surface. Accordingly, pulse phase-resolved intensities and polarizations depend on the angle between the magnetic and spin axes and the observer's viewing direction. In this paper, results are presented from a Monte Carlo simulation of neutron star atmospheres that uses a complex electric field vector formalism to treat polarized radiative transfer due to magnetic Thomson scattering. General relativistic influences on the propagation of light from the stellar surface to a distant observer are taken into account. The paper outlines a range of theoretical predictions for pulse profiles at different X-ray energies, focusing on magnetars and also neutron stars of lower magnetization. By comparing these models with observed intensity and polarization pulse profiles for the magnetar 1RXS J1708-40, and the light curve for the pulsar PSR J0821-4300, constraints on the stellar geometry angles and the size of putative polar cap hot spots are obtained.

Cepheid masses are particularly necessary to help solving the mass discrepancy, while independent distance determinations provide crucial test of the period-luminosity relation and Gaia parallaxes. We used CHARA/MIRC to measure the astrometric positions of the high-contrast companion orbiting the Cepheid SU Cygni. We also present new radial velocity measurements from the HST. The combination of interferometric astrometry with optical and ultraviolet spectroscopy provides the full orbital elements of the system, in addition to component masses and the distance to the Cepheid system. We measured the mass of the Cepheid, $M_A = 4.859\pm0.058M_\odot$, and its two companions, $M_{Ba} = 3.595 \pm 0.033 M_\odot$ and $M_{Bb} = 1.546 \pm 0.009 M_\odot$. This is the most accurate existing measurement of the mass of a Galactic Cepheid (1.2%). Comparing with stellar evolution models, we show that the mass predicted is higher than the measured mass of the Cepheid, similar to conclusions of our previous work. We also measured the distance to the system to be $926.3 \pm 5.0$pc, i.e. an unprecedented parallax precision of $6\mu$as (0.5%), being the most precise and accurate distance for a Cepheid. Such precision is similar to what is expected by Gaia for the last data release (DR5 in $\sim$ 2030) for single stars fainter than G = 13, but is not guaranteed for stars as bright as SU Cyg. We demonstrated that evolutionary models remain inadequate in accurately reproducing the measured mass, often predicting higher masses for the expected metallicity, even when factors such as rotation or convective core overshooting are taken into account. Our precise distance measurement allowed us to compare prediction period-luminosity relations. We found a disagreement of 0.2-0.5 mag with relations calibrated from photometry, while relations calibrated from direct distance measurement are in better agreement.

Asteroseismology has become an indispensable method for measuring stellar ages and radii, while binary systems remain the most prevalent tool for determining stellar masses. The synergy of the two, namely pulsating stars in binary systems, offer even more than the sum of their parts. The sometimes-overwhelming number of pulsation models to be examined for asteroseismic modelling can be tightly constrained when dynamical masses for both components are available. Binaries offer twice the opportunity to measure an asteroseismic age, which is then applicable to both components of a system, often providing ages for stars that are otherwise very difficult to determine. Some stellar physics, such as the strength of internal mixing or of core overshoot, is so difficult to infer that only in binary systems do sufficient constraints exist to advance our asteroseismic models. The pulsations themselves can also be used to infer dynamical masses through pulsation timing, while eclipsing binaries provide opportunities to test asteroseismic scaling relations. In these proceedings of an invited talk I selectively review the synergies afforded by pulsations in binaries, consisting of a variety of main-sequence primary spectral types, to inferences made from the oscillations of red giants, even when their companions are undetectable. I also describe how the field is changing as we become more data rich through each generation of large photometric survey.

We report the discovery of a unique quasar-dusty star-forming galaxy (DSFG) system at $z = 5.63$, consisting of the bright quasar J1133+1603 ($M_{\rm UV} = -27.42$) and its compact, dust-obscured companion, J1133c. ALMA observations reveal a prominent [C II] bridge connecting the quasar and DSFG, indicating ongoing interaction at a projected separation of 1.8 arcsec ($\sim$10 proper kpc). J1133c exhibits unusually bright and broad [C II] emission ($L_{\rm [CII]} > 10^{43}$ erg s$^{-1}$, FWHM $> 500$ km s$^{-1}$), with a [C II] luminosity five times that of the quasar, suggesting intense star formation or potential AGN activity. The inferred star formation rate from [C II] is approximately $10^3$ M$_\odot$ yr$^{-1}$. The remarkable properties of this pair strongly suggest that galaxy interactions may simultaneously trigger both starburst and quasar activity, driving rapid evolution in the early universe.

Astrometric observations with Gaia are expected to play a valuable role in future exoplanet surveys. With current data from Gaia's third data release (DR3), we are sensitive to periods from less than 1 year to more than 4 years but, unlike radial velocity are not as restricted by the orbital inclination of a potential planet. The presence and potential properties of a companion affect the primary's renormalised unit weight error (RUWE) making this a valuable quantity in the search for exoplanets. Using this value and the fitted astrometric tracks from Gaia, we use Bayesian inference to constrain the mass and orbital parameters of companions in known systems. Combining this with radial velocity measurements, we show it is possible to independently measure mass and inclination and suggest HD 66141 b is a possible brown dwarf with maximum mass 23.9$^{+7.2}_{-6.4}$ M$_{\mathrm{J}}$. We show how this method may be applied to directly imaged planets in the future, using $\beta$-Pictoris c as an example but note that the host star is bright and active, making it difficult to draw clear conclusions. We show how the next Gaia data release, which will include epoch astrometry, will allow us to accurately constrain orbital parameters from astrometric data alone, revolutionising future searches for exoplanets. Combining predicted observational limits on planet mass with theoretical distributions, we estimate the probability that a star with a given RUWE will host a detectable planet, which will be highly valuable in planning future surveys.

We reanalyze 15 yr data recorded by the Fermi Large Area Telescope in a region around supernova remnant (SNR) $\gamma$-Cygni from 100 MeV to 1 TeV, and find that the spectra of two extended sources associated with the southeast radio SNR arc and the TeV VERITAS source can be described well by single power-laws with photon indices of $2.149\pm0.005$ and $2.01\pm0.06$, respectively. Combining with high resolution gas observation results, we model the emission in the hadronic scenario, where the $\gamma$-ray emission could be interpreted as escaped CRs illuminating a surrounding Molecular Cloud (MC) plus an ongoing shock-cloud interaction component. In this scenario, the difference between these two GeV spectral indices is due to the different ratios of the MC mass between the escaped component and the trapped component in the two regions. We further analyze, in a potential pulsar halo region, the relationship between energy density $\varepsilon_{\rm{e}}$, spin-down power $\dot{E}$, and the $\gamma$-ray luminosity $L_{\gamma}$ of PSR J2021+4026. Our results indicate that the existence of a pulsar halo is unlikely. On the other hand, considering the uncertainty on the SNR distance, the derived energy density $\varepsilon_{\rm{e}}$ might be overestimated, thus the scenario of a SNR and a pulsar halo overlapping in the direction of the line of sight (LOS) cannot be ruled out.

Migration of bodies under the gravitational influence of almost formed planets was studied, and probabilities of their collisions with the Earth and other terrestrial planets were calculated. Based on the probabilities, several conclusions on the accumulation of the terrestrial planets have been made. The outer layers of the Earth and Venus could accumulate similar planetesimals from different regions of the feeding zone of the terrestrial planets. The probabilities of collisions of bodies during their dynamical lifetimes with the Earth could be up to 0.001-0.01 for some initial semi-major axes between 3.2 and 3.6 AU, whereas such probabilities did not exceed 10^-5 at initial semi-major axes between 12 and 40 AU. The total mass of water delivered to the Earth from beyond Jupiter's orbit could exceed the mass of the Earth's oceans. The zone of the outer asteroid belt could be one of the sources of the late-heavy bombardment. The bodies that came from the zone of Jupiter and Saturn typically collided with the Earth and the Moon with velocities from 23 to 26 km/s and from 20 to 23 km/s, respectively.

A recent study of the distribution of dwarf galaxies in the MATLAS sample in galaxy groups revealed an excess of flattened satellite structures, reminiscent of the co-rotating planes of dwarf galaxies discovered in the local Universe. If confirmed, this lends credence to the plane-of-satellite problem and further challenges the standard model of hierarchical structure formation. However, with only photometric data and no confirmation of the satellite membership, the study could not address the plane-of-satellite problem in full detail. Here we present spectroscopic follow-up observations of one of the most promising planes-of-satellites candidates in the MATLAS survey, the satellite system of NGC 474. Employing MUSE at the VLT and full spectrum fitting, we studied 13 dwarf galaxy candidates and confirmed nine to be members of the field around NGC 474. Measuring the stellar populations of all observed galaxies, we find that the MATLAS dwarfs have lower metallicities than the Local Group dwarfs at given luminosity. Two dwarf galaxies may form a pair of satellites based on their close projection and common velocity. Within the virial radius, we do not find a significant plane-of-satellites, however, there is a sub-population of six dwarf galaxies which seem to be anti-correlated in phase-space. Due to the low number of dwarf galaxies, this signal may arise by chance. With over 2000 dwarf galaxy candidates found in the MATLAS survey, this remains an intriguing data set to study the plane-of-satellites problem in a statistical fashion once more follow-up observations have been conducted.

Eclipsing Algol-type systems containing a $\delta$ Scuti (hereafter $\delta$ Sct) star enable precise determination of physical parameters and the investigation of stellar internal structure and evolution. We present the absolute parameters of CZ Aquarius (hereafter CZ Aqr) based on TESS data. CZ Aqr has an orbital period of 0.86275209 d, a mass ratio of 0.489 (6), and the secondary component nearly fills its Roche lobe. $O-C$ analysis reveals a downward parabolic trend and a cyclical variation with a period of 88.2 yr. The downward parabola suggests a long-term decrease in the orbital period with $\dot{P}$ = -3.09$\times$$10^{-8}$ d $\textrm{yr}^{-1}$. The mass loss rate is estimated to be 4.54$\times$$10^{-9}$ M$_{\odot}$ $\textrm{yr}^{-1}$, which possibly due to magnetic stellar wind or hot spot. The cyclical variation might be caused by the light travel time effect via the presence of a third body with a minimum mass of $M_{3min}$ = 0.312 (21) M$_{\odot}$. Additionally, there are two possible celestial bodies in a 2:7 resonance orbit around CZ Aqr. The asymmetric light curve is explained by adding a hot spot on the surface of the primary star. After removing the binary model, 26 frequencies were extracted from TESS data. Two radial modes were newly identified among three possible independent frequencies. Our results show that the eclipsing Algol-type system is composed of a $\delta$ Sct primary star and a subgiant star in a quadruple system.

In this study we report spatially resolved, wideband spectral properties of three giant radio galaxies (GRGs) in the COSMOS field: MGTC J095959.63+024608.6 , MGTC J100016.84+015133.0 and MGTC J100022.85+031520.4. One such galaxy MGTC J100022.85+031520.4 is reported here for the first time with a projected linear size of 1.29 Mpc at a redshift of 0.1034. Unlike the other two, it is associated with a brightest cluster galaxy (BCG), making it one of the few GRGs known to inhabit cluster environments. We examine the spectral age distributions of the three GRGs using new MeerKAT UHF-band (544-1088 MHz) observations, and $L$-band (900-1670 MHz) data from the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey. We test two different models of spectral ageing, the Jaffe-Perola and Tribble models, using the Broadband Radio Astronomy Tools (\textsc{brats}) software which we find agree well with each other. We estimate the Tribble spectral age for MGTC J095959.63+024608.6 as 68 Myr, MGTC J100016.84+015133.0 as 47 Myr and MGTC J100022.85+031520.4 as 67 Myr. We find significant disagreements between these spectral age estimates and the estimates of the dynamical ages of these GRGs, modelled in cluster and group environments. Our results highlight the need for additional processes which are not accounted for in either the dynamic age or spectral age estimations.

Aims. Our goals are to characterise the kinematic properties and to identify young and old stars among the M dwarfs of the CARMENES input catalogue. Methods. We compiled the spectral types, proper motions, distances, and radial velocities for 2187 M dwarfs. We used the public code SteParKin to derive their galactic space velocities and identify members in the different galactic populations. We also identified candidate members in young stellar kinematic groups, with ages ranging from 1 Ma to 800 Ma with SteParKin, LACEwING, and BANYAN {\Sigma}. We removed known close binaries and perform an analysis of kinematic, rotation, and activity indicators (rotational periods and projected velocities, Halpha, X-rays, and UV emission) for 1546 M dwarfs. We defined five rotation-activity-colour relations satisfied by young ({\tau} <= 800 Ma) stars. Results. We identified 191 young M dwarf candidates (~12%), 113 of which are newly recognised in this work. In this young sample, there are 118 very active stars based on H{\alpha} emission, fast rotation, and X-ray and UV emission excess. Of them, 27 have also strong magnetic fields, 9 of which are likely younger than 50 Ma. Additionally, there are 87 potentially young stars and 99 stars with a dubious youth classification, which may increase the fraction of young stars to an astounding 24%. Only one star out of the 2187 exhibits kinematics typical of the old Galactic halo. Conclusions. A combined analysis of kinematic and rotation-activity properties provides a robust method for identifying young M dwarfs from archival data. However, more observational efforts are needed to ascertain the true nature of numerous young star candidates in the field and, perhaps more importantly, to precisely quantify their age.

Close-binary central stars of planetary nebulae offer a unique tool with which to study the critical and yet poorly understood common-envelope phase of binary stellar evolution. Furthermore, as the nebula itself is thought to comprise the ionised remnant of the ejected common envelope, such planetary nebulae can be used to directly probe the mass, morphology and dynamics of the ejecta. In this review, I summarise our current understanding of the importance of binarity in the formation of planetary nebulae as well as what they may be able to tell us about the common-envelope phase - including the possible relationships with other post-common-envelope phenomena like stellar mergers, novae and type Ia supernovae.

The present Martian climate is characterized by a cold and dry environment with a thin atmosphere of carbon dioxides (CO2). In such conditions, the planetary climate and habitability are determined by the distribution of CO2 between exchangeable reservoirs, that is the atmosphere, ice caps, and regolith. This produces unique responses of the Martian CO2-driven climate system to variations of astronomical forcings. Specifically, it has been shown that the phenomenon called an atmospheric collapse occurs when the axial obliquity is low, affecting the Martian climatic evolution. However, the behavior of the Martian climate system and the accompanying changes in climate and habitability of such planets remain ambiguous. Here we employed a latitudinally-resolved Martian energy balance model and assessed the possible climate on Mars for wider ranges of orbital parameters, solar irradiance, and total exchangeable CO2 mass. We show that the atmospheric collapse occurs when the obliquity is below ~10 degrees when other parameters are kept at the present Mars condition. We also show that the climate solutions on Mars depend on orbital parameters, solar luminosity, and the total exchangeable CO2 mass. We found that the atmospheric collapse would have occurred repeatedly in the history of Mars following the variation of the axial obliquity, while the long-term evolution of atmospheric pCO2 is also affected by the changes in the total exchangeable CO2 mass in Martian history. Even considering the broad ranges of these parameters, the habitable conditions in the Martian CO2-driven dry climate system would be limited to high-latitude summers.

Classical Be stars, the "e" standing for the presence of spectroscopic line emission, are main sequence stars of spectral type B that are able to form a gaseous disk in Keplerian motion from star-ejected matter. The main driver of this capability is the rapid surface rotation, which might be acquired via binary interaction or through internal stellar evolution, but additional mechanisms, such as nonradial pulsation, usually enable a star to become a Be star well below the actual critical rotation threshold. The angular momentum loss through the disk then keeps the star below the critical rotation value for the rest of its main sequence life span. It is one of the oldest standing research fields of astronomy, since the first discovery of a Be star in 1866. The article, therefore, not only presents the properties of Be stars, but as well the history of the field. The current main research topics, discussed in greater detail, are: 1) the variability of the central object and the nature of Be stars as nonradially pulsating stars, 2) the physics of the viscosity governed circumstellar disk and its variability, which can serve as proxy for the more common, but typically harder to observe viscuous accretion disks, and 3) the role of binarity both in the formation of Be stars as rapid rotators, and as well their impact on the observed properties of these stars.

Mass loss through a stellar wind is an important physical process that steers the evolution of massive stars and controls the properties of their end-of-life products, such as the supernova type and the mass of compact remnants. For an accurate mass loss determination, the inhomogeneities in the wind, known as clumping, needs to be taking into account. We aim to improve empirical estimates of mass loss and wind clumping for hot main-sequence massive stars, study the dependence of both properties on the metallicity, and compare the theoretical predictions to our findings. We analyzed the optical and UV spectra of 13 O-type stars in the Small Magellanic Cloud galaxy, which has a metallicity of $\sim 0.2\,Z_\odot$. We quantified the stellar atmosphere, outflow, and wind-clumping properties. To probe the role of metallicity, we compared our findings to studies of Galactic and Large Magellanic Cloud samples that were analyzed with similar methods. We find significant variations in the wind-clumping properties of the target stars, with clumping starting at flow velocities $0.01 - 0.23$ of the terminal wind velocity and reaching clumping factors $f_{\rm cl} = 2 - 30$. In the luminosity ($\log L / L_{\odot} = 5.0 - 6.0$) and metallicity ($Z/Z_{\odot} = 0.2 - 1$) range we considered, we find that the scaling of the mass loss $\dot{M}$ with metallicity $Z$ varies with luminosity. At $\log L/L_{\odot} = 5.75$, we find $\dot{M} \propto Z^m$ with $m = 1.02 \pm 0.30$, in agreement with pioneering work in the field. For lower luminosities, however, we obtain a significantly steeper scaling of $m > 2$. The monotonically decreasing $m(L)$ behavior adds a complexity to the functional description of the mass-loss rate of hot massive stars. Although the trend is present in the predictions, it is much weaker than we found here.

Asteroid Didymos, recently targeted by the NASA DART mission, is also planned to be visited by the ESA Hera mission. The main goal of the DART mission was to impact Dimorphos, the small satellite of Didymos, which was accomplished in September 2022. This collision altered the Didymos-Dimorphos system, generating a notable quantity of ejecta that turned Dimorphos into an active asteroid, with some ejecta potentially settling on the surfaces of both components. This prompts the investigation into the extent of post-impact surface alterations on these bodies compared to their original states. The purpose of this study is to evaluate the pre-impact thermal inertia of Didymos independently. We employed ASTERIA, an alternative to conventional thermophysical modeling, to estimate the surface thermal inertia of Didymos. The approach is based on a model-to-measurement comparison of the Yarkovsky effect-induced drift on the orbital semi-major axis. These results, alongside existing literature, enable an evaluation of the impact-induced alterations in Didymos's thermal inertia. Our nominal estimate with a constant thermal inertia model stands at $\Gamma = 211_{-55}^{+81}$ J m$^{-2}$ K$^{-1}$ s$^{-1/2}$, while assuming it varies with the heliocentric distance with an exponent of $-0.75$ thermal inertia of Didymos is found to be $258_{-63}^{+94}$ J m$^{-2}$ K$^{-1}$ s$^{-1/2}$. Subsequent verification confirmed that this result is robust against variations in unknown physical parameters. The thermal inertia estimates for Didymos align statistically with values reported in the literature, derived from both pre- and post-impact data. The forthcoming Hera mission will provide an opportunity to corroborate these findings further. Additionally, our results support the hypothesis that the thermal inertia of near-Earth asteroids is generally lower than previously expected.

Periodic variability in active galactic nuclei (AGNs) is a promising method for studying sub-parsec supermassive black hole binaries (SMBHBs), which are a challenging detection target. While extensive searches have been made in the optical, X-ray and gamma-ray bands, systematic infrared (IR) studies remain limited. Using data from the Wide-field Infrared Survey Explorer (WISE), which provides unique decade-long mid-IR light curves with a six-month cadence, we have conducted the first systematic search for SMBHB candidates based on IR periodicity. Analyzing a parent sample of 48,932 objects selected from about half a million AGNs, we have identified 28 candidate periodic AGNs with periods ranging from 1,268 to 2,437 days (in the observer frame) by fitting their WISE light curves with sinusoidal functions. However, our mock simulation of the parent sample indicates that stochastic variability can actually produce a similar number of periodic sources, underscoring the difficulty in robustly identifying real periodic signals with WISE light curves, given their current sampling. Notably, we found no overlap between our sample and optical periodic sources, which can be explained by a distinct preference for certain periods due to selection bias. By combining archived data from different surveys, we have identified SDSS J140336.43+174136.1 as a candidate exhibiting periodic behavior in both optical and IR bands, a phenomenon that warrants further validation through observational tests. Our results highlight the potential of IR time-domain surveys, including future missions such as the Nancy Grace-Roman Space Telescope, for identifying periodic AGNs, but complementary tests are still needed to determine their physical origins such as SMBHBs.

The discrepancy between models and data on the muon content in air showers generated by ultra-high energy cosmic rays still needs to be solved. The CONEX simulation framework provides a flexible tool to assess the impact of different interaction properties and address the muon puzzle. In this work, we present the multidimensional extension of CONEX and show its performance compared to CORSIKA by discussing muon-related air-shower features for three experiments: KASCADE, IceTop, and the Pierre Auger Observatory. We also implement an effective version of the core-corona model to demonstrate the impact of the core effect, as observed at the LHC, on the muon content in air showers produced by ultra-high energy cosmic rays. At a primary energy of $E_0 = 10^{19}$ eV, we obtain an increase of $15\%$ to $20\%$ in the muon content.

We present polarization images with the Karl G. Jansky Very Large Array (VLA) in A and B-array configurations at 6 GHz of 7 radio-loud (RL) quasars and 8 BL Lac objects belonging to the Palomar-Green (PG) `blazar' sample. This completes our arcsecond-scale polarization study of an optically-selected volume-limited blazar sample comprising 16 radio-loud quasars and 8 BL Lac objects. Using the VLA, we identify kpc-scale polarization in the cores and jets/lobes of all the blazars, with fractional polarization varying from around $0.8 \pm 0.3$% to $37 \pm 6$%. The kpc-scale jets in PG RL quasars are typically aligned along their parsec-scale jets and show apparent magnetic fields parallel to jet directions in their jets/cores and magnetic field compression in their hotspots. The quasars show evidence of interaction with their environment as well as restarted AGN activity through morphology, polarization and spectral indices. These quasi-periodic jet modulations and restarted activity may be indicative of an unstable accretion disk undergoing transition. We find that the polarization characteristics of the BL Lacs are consistent with their jets being reoriented multiple times, with no correlation between their core apparent magnetic field orientations and pc-scale jet directions. We find that the low synchrotron peaked BL Lacs show polarization and radio morphology features typical of `strong' jet sources as defined by Meyer et al. (2011) for the `blazar envelope scenario', which posits a division based on jet profiles and velocity gradients rather than total jet power.

High-mass young stellar objects (HMYSOs) can exhibit episodic bursts of accretion, accompanied by intense outflows and luminosity variations. Thermal Instability (TI) due to Hydrogen ionisation is among the most promising mechanisms of episodic accretion in low mass ($M_*\lesssim 1M_{\odot}$) protostars. Its role in HMYSOs has not yet been elucidated. Here, we investigate the properties of TI outbursts in young, massive ($M_*\gtrsim 5M_{\odot}$) stars, and compare them to those observed so far. Our simulations show that modelled TI bursts can replicate the durations and peak accretion rates of long (a few years to decades) outbursts observed in HMYSOs with similar mass characteristics. However, they struggle with short-duration (less than a year) bursts with short (a few weeks or months) rise times, suggesting the need for alternative mechanisms. Moreover, while our models match the durations of longer bursts, they fail to reproduce the multiple outbursts seen in some HMYSOs, regardless of model parameters. We also emphasise the significance of not just evaluating model accretion rates and durations, but also performing photometric analysis to thoroughly evaluate the consistency between model predictions and observational data. Our findings suggest that some other plausible mechanisms, such as gravitational instabilities and disc fragmentation can be responsible for generating the observed outburst phenomena in HMYSOs and underscore the need for further investigation into alternative mechanisms driving short outbursts. However, the physics of TI is crucial in sculpting the inner disc physics in the early bright epoch of massive star formation, and comprehensive parameter space exploration and the use of 2D modeling are essential for obtaining a more detailed understanding of the underlying physical processes.

The analysis of the rotation rate of individual sunspots and pores was performed according to the data of the processing of observations by the \textit{Solar Dynamics Observatory/Helioseismic and Magnetic Imager} (SDO/HMI) in the period 2010\,--\,2024. Sunspots stood out in the images in the continuum. To accurately track the spots, we processed 5 images for each day. To determine the polarity of the magnetic field, we superimposed the contours of sunspots on observations of magnetic fields at the same time. This made it possible to track the movement of more than 210 thousand individual sunspots and pores. It is found that the rotation rate is influenced by the rotation rate of the solar atmosphere and the systematic proper motions of the spots. Sunspots and pores of the leading polarity have a rate of meridional movement $\approx 2.4\%$ faster than spots of the trailing polarity. We also found that regular sunspots, which have umbra and penumbra, rotate $\approx 1.5\%$ faster than solar pores, in which penumbra is absent. The dependence of the rotation rate on these area is found. For sunspots with an area of $S> 10$ $\mu$hm, the rotation rate is practically independent of these area. Small sunspots, with an area of lower than $S< 10$ $\mu$hm, rotate $\approx 1.7\%$ slower.

We present the first set of galaxy scaling relations derived from kinematic models of the Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY) pilot phase observations. Combining the results of the first and second pilot data releases, there are 236 available kinematic models. We develop a framework for robustly measuring HI disk structural properties from these kinematic models; applicable to the full WALLABY survey. Utilizing this framework, we obtained the HI size, a measure of the rotational velocity, and angular momentum for 148 galaxies. These comprise the largest sample of galaxy properties from an untargetted, uniformly observed and modelled HI survey to date. We study the neutral atomic Hydrogen (HI) size-mass, size-velocity, mass-velocity, and angular momentum-mass scaling relations. We calculate the slope, intercept, and scatter for these scaling relations and find that they are similar to those obtained from other HI surveys. We also obtain stellar masses for 92 of the 148 robustly measured galaxies using multiband photometry through the Dark Energy Sky Instrument Legacy Imaging Survey Data Release-10 images. We use a subset of 61 of these galaxies that have consistent optical and kinematic inclinations to examine the stellar and baryonic Tully Fisher relations, the gas fraction-disk stability and gas fraction-baryonic mass relations. These measurements and relations demonstrate the unprecedented resource that WALLABY will represent for resolved galaxy scaling relations in HI.

Fast radio bursts (FRBs) are bright milliseconds-duration radio bursts from cosmological distances. Despite intense observational and theoretical studies, their physical origin is still mysterious. One major obstacle is the lack of identification of multi-wavelength counterparts for FRBs at cosmological distances. So far, all the searches other than in the radio wavelength, including those in the gamma-ray energies, have only left upper limits. Here we report a gigaelectronvolt (GeV) gamma-ray flare lasting 15.6 seconds as well as additional evidence of variable gamma-ray emission in temporal and spatial association with the hyper-active, newly discovered repeating FRB 20240114A, which has been localized to a dwarf galaxy at a redshift of 0.13. The energetic, short GeV gamma-ray flare reached a prompt isotropic luminosity of the order of ${10}^{48}~{\rm ergs~{s}^{-1}}$. The additional less-significant gamma-ray flares, if true, also have similar luminosities; such flares could contribute to a 5-day average luminosity of the order of ${10}^{45}~{\rm ergs~{s}^{-1}}$. These high-luminosity flares challenge the traditional FRB engine scenario involving a seconds-period magnetar. Rather, it suggests a powerful, long-lived, but newborn energy source at the location of this active repeater, either directly powering the bursts or indirectly triggering bursts in the vicinity of the FRB engine.

We present the design, rationale, properties and catalogs of the MusE Gas FLOw and Wind survey (MEGAFLOW), a survey of the cool gaseous halos of $z\sim1$ galaxies using low-ionization MgII absorption systems. The survey consists of 22 quasar fields selected from the Sloan Digital Sky Survey (SDSS) having multiple ($\geq3$) strong MgII absorption lines over the redshift range $0.3<z<1.5$. Each quasar was observed with the Multi-Unit Spectroscopic Explorer (MUSE) and the Ultraviolet and Visual Echelle Spectrograph (UVES), for a total of 85~hr and 63~hr, respectively. The UVES data resulted in 127 MgII absorption lines over $0.25<z<1.6$, with a median rest-frame equivalent width (REW) $3\sigma$ limit of $\approx 0.05$~Å. The MUSE data resulted in $\sim$2400 galaxies of which 1403 with redshift confidence ZCONF$>1$, i.e. more than 60 galaxies per arcmin$^{2}$. They were identified using a dual detection algorithm based on both continuum and emission line objects. The achieved [OII] 50\%\ completeness is 3.7$\times 10^{-18}$ erg/s/cm$^2$ (corresponding to SFR$>0.01$ M$_\odot$ yr$^{-1}$ at $z=1$) using realistic mock [OII] emitters and the 50\%\ completeness is $m_{F775W}\approx26$ AB magnitudes for continuum sources. We find that (i) the fraction of [OII] emitting galaxies which have no continuum is $\sim15$\%; (ii) the success rate in identifying at least one galaxy within 500 km/s and 100 kpc is $\approx90$\%\ for MgII absorptions with $W_r^{2796}\gtrsim0.5$~Å; (iii) the mean number of galaxies per MgII absorption is $2.9\pm1.6$ within the MUSE field-of-view; (iv) of the 80 MgII systems at $0.3<z<1.5$, 40 (20) have 1 (2) galaxies within 100 kpc, respectively; (v) all but two host galaxies have stellar masses $M_\star>10^9$ M$_\odot$, and star-formation rates $>1$ M$_\odot$ yr$^{-1}$.

Stellar occultations provide a powerful tool to explore objects of the outer solar system. The Gaia mission now provides milli-arcsec accuracy on the predictions of these events and makes possible observations that were previously unthinkable. Occultations return kilometric accuracies on the three-dimensional shape of bodies irrespective of their geocentric distances, with the potential of detecting topographic features along the limb. From the shape, accurate values of albedo can be derived, and if the mass is known, the bulk density is pinned down, thus constraining the internal structure and equilibrium state of the object. Occultations are also extremely sensitive to tenuous atmospheres, down to the nanobar level. They allowed the monitoring of Pluto's and Triton's atmospheres in the last three decades, constraining their seasonal evolution. They may unveil in the near future atmospheres around other remote bodies of the solar system. Since 2013, occultations have led to the surprising discovery of ring systems around the Centaur object Chariklo, the dwarf planet Haumea and the large trans-Neptunian object Quaoar, while revealing dense material around the Centaur Chiron. This suggests that rings are probably much more common features than previously thought. Meanwhile, they have raised new dynamical questions concerning the confining effect of resonances forced by irregular objects on ring particles. Serendipitous occultations by km-sized trans-Neptunian or Oort objects has the potential to provide the size distribution of a population that suffered few collisions until now, thus constraining the history of primordial planetesimals in the 1-100 km range.

The microphysics of the intracluster medium (ICM) in galaxy clusters is still poorly understood. Observational evidence suggests that the effective viscosity is suppressed by plasma instabilities that reduce the mean free path of particles. Measuring the effective viscosity of the ICM is crucial to understanding the processes that govern its physics on small scales. The trails of ionized interstellar medium left behind by the so-called jellyfish galaxies can trace the turbulent motions of the surrounding ICM and constrain its local viscosity. We present the results of a systematic analysis of the velocity structure function (VSF) of the H$\alpha$ line for ten galaxies from the GASP sample. The VSFs show a sub-linear power law scaling below 10 kpc which may result from turbulent cascading and extends to 1 kpc, below the supposed ICM dissipation scales of tens of kpc expected in a fluid described by Coulomb collisions. Our result constrains the local ICM viscosity to be 0.3-25$\%$ of the expected Spitzer value. Our findings demonstrate that either the ICM particles have a smaller mean free path than expected in a regime defined by Coulomb collisions, or that we are probing effects due to collisionless physics in the ICM turbulence.

Neutron star - black hole (NSBH) mergers that undergo tidal disruption may launch jets that could power a gamma-ray burst. We use a population of simulated NSBH systems to measure jet parameters from the gravitational waves emitted by these systems. The conditions during the tidal disruption and merger phase required to power a gamma-ray burst are uncertain. It is likely that the system must achieve some minimum remnant baryonic mass after the merger before a jet can be launched to power a gamma-ray burst. Assuming a fiducial neutron star equation of state, we show how Bayesian hierarchical inference can be used to infer the minimum remnant mass required to launch a gamma-ray burst jet as well as the maximum gamma-ray burst viewing angle to detect a gamma-ray burst. We find that with 200 NSBH observations, we can measure the minimum disk mass to within 0.01 solar masses at 90% credibility. We simultaneously infer the maximum gamma-ray burst viewing angle to within 13 degrees at 90% credibility. We conclude that upcoming upgrades to the LIGO observatories may provide important new insights into the physics of NSBH jets.

The impact of disk-locking on the stellar properties related to magnetic activity from the theoretical point of view is investigated. We use the ATON stellar evolution code to calculate theoretical values of convective turnover times ($\tau_{\rm c}$) and Rossby numbers ($Ro$, the ratio between rotation periods and $\tau_{\rm c}$) for pre-main sequence (pre-MS) and main sequence (MS) stars. We investigate how $\tau_{\rm c}$ varies with the initial rotation period and with the disk lifetime, using angular momentum conserving models and models simulating the disk-locking mechanism. In the latter case, the angular velocity is kept constant, during a given locking time, to mimic the magnetic locking effects of a circumstellar disk. The local convective turnover times generated with disk-locking models are shorter than those obtained with angular momentum conserving models. The differences are smaller in the early pre-MS, increase with stellar age and become more accentuated for stars with $M$$\geq$$1 {\rm M}_{\odot}$ and ages greater than 100 Myr. Our new values of $\tau_{\rm c}$ were used to estimate $Ro$ for a sample of stars selected from the literature in order to investigate the rotation-activity relationship. We fit the data with a two-part power-law function and find the best fitting parameters of this relation. The differences we found between both sets of models suggest that the star's disk-locking phase properties affect its Rossby number and its position in the rotation-activity diagram. Our results indicate that the dynamo efficiency is lower for stars that had undergone longer disk-locking phases.

Magnetic fields play a crucial role in various astrophysical processes within the intracluster medium, including heat conduction, cosmic ray acceleration, and the generation of synchrotron radiation. However, measuring magnetic field strength is typically challenging due to the limited availability of Faraday Rotation Measure sources. To address the challenge, we propose a novel method that employs Convolutional Neural Networks (CNNs) alongside synchrotron emission observations to estimate magnetic field strengths in galaxy clusters. Our CNN model is trained on either Magnetohydrodynamic (MHD) turbulence simulations or MHD galaxy cluster simulations, which incorporate complex dynamics such as cluster mergers and sloshing motions. The results demonstrate that CNNs can effectively estimate magnetic field strengths with median uncertainties of approximately $0.22\mu$G, $0.01\mu$G, and $0.1\mu$G for $\beta = 100$, 200, and 500 conditions, respectively. Additionally, we have confirmed that our CNN model remains robust against noise and variations in viewing angles with sufficient training, ensuring reliable performance under a wide range of observational conditions. We compare the CNN approach with the traditional magnetic field strength estimates method that assumes equipartition between cosmic ray electron energy and magnetic field energy. Unlike the equipartition method, this CNN approach does not rely on the equipartition assumption, offering a new perspective for comparing traditional estimates and enhancing our understanding of cosmic ray acceleration mechanisms.

We propose a new model-independent reconstruction method for the matter power spectrum based on its time dependence and a combination of observations from different redshifts. The method builds on a perturbative expansion in terms of the linear growth function, with each coefficient in the expansion being a free function of scale, to be reconstructed from the data. When using the linear growth function of a specific cosmological model, e.g. $\Lambda$CDM, the reconstruction can serve as a consistency check for non-linear modeling in that given model, as well as a new method for detecting departures from the assumed model in the data. As an application, we show how using DES Y3 3x2pt and Planck PR4 CMB lensing data, assuming a $\Lambda$CDM linear growth and first order expansion, the reconstructed matter power spectrum $P_{\rm m}(k)$ is compatible with that computed from $\Lambda$CDM and halo model. In particular, we show that the method reconstructs the non-linear part of $P_{\rm m}(k)$ for $k\gtrsim 1\ \rm{Mpc}^{-1}$ without the need of assuming a non-linear model.

We conducted the MeerKAT Vela Supercluster survey, named Vela$-$HI, to bridge the gap between the Vela SARAO MeerKAT Galactic Plane Survey (Vela$-$SMGPS, $-2^{\circ} \leq b \leq 1^{\circ}$), and optical and near-infrared spectroscopic observations of the Vela Supercluster (hereafter Vela$-$OPT/NIR) at $|b| \gtrsim 7^{\circ}$. Covering coordinates from $263^{\circ} \leq \ell \leq 284^{\circ}$ and $1^{\circ} \leq b \leq 6.2^{\circ}$ above, and $-6.7^{\circ} \leq b \leq -2^{\circ}$ below the Galactic Plane (GP), we sampled 667 fields spread across an area of ${\sim} \rm 242 ~deg^2$. With a beam size of ${\sim} 38'' \times 31''$, Vela$-$HI achieved a sensitivity of $\langle \rm rms \rangle = 0.74$ mJy beam$^{-1}$ at 44.3 km s$^{-1}$ velocity resolution over ${\sim}$67 hours of observations. We cataloged 719 galaxies, with only 211 (29%) previously documented in the literature, primarily through the HIZOA, 2MASX, and WISE databases. Among these known galaxies, only 66 had optical spectroscopic redshift information. We found marginal differences of less than one channel resolution for all galaxies in common between HIZOA and Vela$-$SMGPS, and a mean difference of $70 \pm 15$ km s$^{-1}$ between optical and HI velocities. Combining data from Vela$-$SMGPS, Vela$-$HI, and Vela$-$OPT/NIR confirmed the connection of the Hydra/Antlia filament across the GP and revealed a previously unknown diagonal wall at a heliocentric velocity range of $6500-8000$ km s$^{-1}$. Vela$-$HI reinforces the connection between the first wall at $18500-20000$ km s$^{-1}$ and the inner ZOA. The second wall seems to traverse the GP at $270^{\circ} \leq \ell \leq 279^{\circ}$, where it appears that both walls intersect, jointly covering the velocity range $18500-21500$ km s$^{-1}$.

We extend our time-dependent hydrogen ionization simulations of diffuse ionized gas to include metals important for collisional cooling and diagnostic emission lines. The combination of heating from supernovae and time-dependent collisional and photoionization from midplane OB stars produces emission line intensities (and emission line ratios) that follow the trends observed in the Milky Way and other edge-on galaxies. The long recombination times in low density gas result in persistent large volumes of ions with high ionization potentials, such as O III and Ne III. In particular, the vertically extended layers of Ne III in our time-dependent simulations result in [Ne III] 15$\mu$m/[Ne II] 12$\mu$m emission line ratios in agreement with observations of the edge-on galaxy NGC 891. Simulations adopting ionization equilibrium do not allow for the persistence of ions with high ionization states and therefore cannot reproduce the observed emission lines from low density gas at high altitudes.

In recent years, it has become increasingly clear that space weather disturbances can be triggered by transient upstream mesoscale structures (TUMS), independently of the occurrence of large-scale solar wind (SW) structures, such as interplanetary coronal mass ejections and stream interaction regions. Different types of magnetospheric pulsations, transient perturbations of the geomagnetic field and auroral structures are often observed during times when SW monitors indicate quiet conditions, and have been found to be associated to TUMS. In this mini-review we describe the space weather phenomena that have been associated with four of the largest-scale and the most energetic TUMS, namely hot flow anomalies, foreshock bubbles, travelling foreshocks and foreshock compressional boundaries. The space weather phenomena associated with TUMS tend to be more localized and less intense compared to geomagnetic storms. However, the quiet time space weather may occur more often since, especially during solar minima, quiet SW periods prevail over the perturbed times.

The recent detection of extended $\gamma$-ray emission around middle-aged pulsars is interpreted as inverse-Compton scattering of ambient photons by electron-positron pairs escaping the pulsar wind nebula, which are confined near the system by unclear mechanisms. This emerging population of $\gamma$-ray sources was first discovered at TeV energies and remains underexplored in the GeV range. To address this, we conducted a systematic search for extended sources along the Galactic plane using 14 years of Fermi-LAT data above 10 GeV, aiming to identify a number of pulsar halo candidates and extend our view to lower energies. The search covered the inner Galactic plane ($\lvert l\rvert\leq$ 100$^{\circ}$, $\lvert b\rvert\leq$ 1$^{\circ}$) and the positions of known TeV sources and bright pulsars, yielding broader astrophysical interest. We found 40 such sources, forming the Second Fermi Galactic Extended Sources Catalog (2FGES), most with 68% containment radii smaller than 1.0$^{\circ}$ and relatively hard spectra with photon indices below 2.5. We assessed detection robustness using field-specific alternative interstellar emission models and by inspecting significance maps. Noting 13 sources previously known as extended in the 4FGL-DR3 catalog and five dubious sources from complex regions, we report 22 newly detected extended sources above 10 GeV. Of these, 13 coincide with H.E.S.S., HAWC, or LHAASO sources; six coincide with bright pulsars (including four also coincident with TeV sources); six are associated with 4FGL point sources only; and one has no association in the scanned catalogs. Notably, six to eight sources may be related to pulsars as classical pulsar wind nebulae or pulsar halos.

There is still much uncertainty around the mechanism that rules the accretion of proto-planetary disks. In the last years, Magnetohydrondynamic (MHD) wind-driven accretion has been proposed as a valid alternative to the more conventional viscous accretion. In particular, winds have been shown to reproduce the observed correlation between the mass of the disk Md and the mass accretion rate onto the central star Macc, but this has been done only for specific conditions. It is not clear whether this implies fine tuning or if it is a general result. We investigate under which conditions the observed correlation between the mass of the disk Md and the mass accretion rate onto the central star Macc can be obtained. We find that, in the absence of a correlation between the initial mass M0 and the initial accretion timescale tacc,0, the slope of the Md-Macc correlation depends on the value of the spread of the initial conditions of masses and lifetimes of disks. Then, we clarify the conditions under which a disk population can be fitted with a single power-law. Moreover, we derive an analytical expression for the spread of log(Md/Macc) valid when the spread of tacc is taken to be constant. In the presence of a correlation between M0 and tacc,0, we derive an analytical expression for the slope of the Md-Macc correlation in the initial conditions of disks and at late times. We conclude that MHD winds can predict the observed values of the slope and the spread of the Md-Macc correlation under a broad range of initial conditions. This is a fundamental expansion of previous works on the MHD paradigm, exploring the establishment of this fundamental correlation beyond specific initial conditions.

The strongest and most universal scaling relation between a supermassive black hole and its host galaxy is known as the $M_\bullet-\sigma$ relation, where $M_\bullet$ is the mass of the central black hole and $\sigma$ is the stellar velocity dispersion of the host galaxy. This relation has been studied for decades and is crucial for estimating black hole masses of distant galaxies. However, recent studies suggest the potential absence of central black holes in some galaxies, and a significant portion of current data only provides upper limits for the mass. Here, we introduce a novel approach using a Bayesian hurdle model to analyze the $M_\bullet-\sigma$ relation across 244 galaxies. This model integrates upper mass limits and the likelihood of hosting a central black hole, combining logistic regression for black hole hosting probability with a linear regression of mass on $\sigma$. From the logistic regression, we find that galaxies with a velocity dispersion of $11$, $34$ and $126$ km/s have a $50$%, $90$% and $99$% probability of hosting a central black hole, respectively. Furthermore, from the linear regression portion of the model, we find that $M_\bullet \propto \sigma^{5.8}$, which is significantly steeper than the slope reported in earlier studies. Our model also predicts a population of under-massive black holes ($M_\bullet=10-10^5 M_\odot$) in galaxies with $\sigma \lesssim 127$ km/s and over-massive black holes ($M_\bullet \geq 1.8 \times 10^7$) above this threshold. This reveals an unexpected abundance of galaxies with intermediate-mass and ultramassive black holes, accessible to next-generation telescopes like the Extremely Large Telescope.

We investigate the constraints on the Inert Doublet Model (IDM), a minimal extension of the Standard Model of Particle Physics featuring a scalar dark matter candidate, using data from recent and future gamma-ray observatories. The relevance of the model for indirect searches of dark matter stems from two key features: first, in the high-mass regime, IDM can achieve the correct dark matter relic abundance for masses between approximately 500 GeV and 25 TeV, aligning perfectly with the energy sensitivity of Imaging Atmospheric Cherenkov Telescopes. Second, this regime is dominated by co-annihilation processes, which elevate the thermal-relic velocity-weighted annihilation cross-section to the range of 0.5 $-$ 1.0$\times 10^{-25}$ cm$^3$ s$^{-1}$, thereby enhancing the potential gamma-ray signal from dark matter annihilation. Analyzing recent H.E.S.S. observations of the Galactic Center region, we find that dark matter particle masses within the 1 to 8 TeV range are excluded by current data. Furthermore, we project that the Cherenkov Telescope Array Observatory (CTAO) will comprehensively probe the remaining viable parameter space of the IDM. Our findings are further examined in the context of the most recent theoretical constraints, collider searches, and direct detection results from the LUX-ZEPLIN experiment.

We investigate the effects of Chern-Simons-Gauss-Bonnet gravity on fundamental metrics. This theory involves perturbative corrections to general relativity, as well as two scalar fields, the axion and the dilaton, that arise from Chern-Simons and Gauss-Bonnet gravity modifications respectively. The combined Chern-Simons-Gauss-Bonnet gravity is motivated by a wide range of theoretical and phenomenological perspectives, including particle physics, string theory, and parity violation in the gravitational sector. In this work, we provide the complete set of field equations and equations of motion of the Chern-Simons-Gauss-Bonnet modified gravity theory for a suite of fundamental metrics (Friedmann-Lemaitre-Robertson-Walker, Schwarzschild, spherically symmetric, and perturbed Minkowski), under no prior assumptions on the behavior of the fields. The full set of field equations and equations of motion can be numerically solved and applied to specific observables under certain assumptions, and can be used to place constraints on the Chern-Simons-Gauss-Bonnet modified gravity theory.

The structure and stability of quark stars (QSs) made of interacting quark matter are discussed in this study, taking color superconductivity and perturbative QCD corrections into account. By combining this EoS with the Tolman-Oppenheimer-Volkoff (TOV) equations, we explore the mass-radius ($M-R$) relations of QSs. The analysis is conducted within the framework of $R^2$ gravity, where the gravity model is described by $f(R) = R + a R^2$. Our primary goal is to investigate how variations in the $R^2$ gravity parameter $a$ affect the mass-radius and mass-central density ($M-\rho_c$) relationships of QSs. Furthermore, we study the dynamical stability of these stars by analyzing the impact of anisotropy parameters $\beta$ and the interaction parameter $\lambda$ derived from the EoS, on their stability. Our results demonstrate that the presence of pressure anisotropy plays a significant role in increasing the maximum mass of QSs, with potential implications for the existence of super-massive pulsars. These findings are in agreement with recent astronomical observations, which suggest the possibility of neutron stars exceeding $2M_{\odot}$.

We show that a slowly varying Newton's constant, consistent with existing bounds, can potentially explain a host of observations pertaining to gravitational effects or phenomena across distances spanning from planetary to the cosmological, relying neither on the existence of Dark Matter or (and) Dark Energy, nor on any expected high proportions of either of them in the Universe. It may also have implications at very short distances or quantum gravity scales.

The cosmological constant term (CC), $\Lambda$, is a pivotal ingredient in the standard model of cosmology or $\Lambda$CDM, but it is a rigid quantity for the entire cosmic history. This is unnatural and inconsistent. Different theoretical and phenomenological conundrums suggest that the $\Lambda$CDM necessitates further theoretical underpinning to cope with modern observations. An interesting approach is the framework of the `running vacuum model' (RVM). It endows $\Lambda$ with cosmic dynamics within a fundamental framework since it is based on QFT. In the RVM, the vacuum energy density (VED) appears as a series of powers of the Hubble function and its derivatives, $\rho_{\rm vac} (H, \dot{H},...)$. In the current universe, $\rho_{\rm vac}$ changes as $\sim H^2$. Higher order effects ${\cal O}(H^4)$, on the other hand, can be responsible for a new mechanism of inflation (RVM-inflation). On the practical side the RVM can alleviate the cosmological tensions on $\sigma_8$ and $H_0$. An intriguing smoking gun signature of the RVM is that its equation of state can mimic quintessence, as recently observed by DESI, so the vacuum can be the sought-for dynamical DE. At a deeper theoretical level, the RVM-renormalized form of the VED can avoid extreme fine tuning related to the well-known cosmological constant problem. Overall, the RVM has the capacity to impinge positively on relevant theoretical and practical aspects of modern cosmology.

In this work, we linearize the field equations in the $f(R)$ theory using the Starobinsky model, $R+R^2/(6m^2)$, and explore the impact of modifications to the gravitational field equations on the propagation and structure of gravitational waves. An equation for the trace of the perturbation was then derived and decomposed with the aid of an auxiliary field that obeyed the pure wave equation and was sourced by the matter-energy distribution, while also acting as a fictitious source for generating the actual perturbation via the Klein-Gordon equation. The fields were expressed in terms of Green's functions, whose symmetry properties facilitated the solution of the trace equation. This trace value was then substituted into the linearized field equation to determine the perturbation tensor in terms of a modified or effective matter-energy distribution. We subsequently calculated the components of the quadrupole moment tensor as well as the perturbation tensor for a binary star system and compared them to the General Relativity case. The results indicate that the amplitude of the oscillation depends on the orbital parameters, specifically: the angular frequency and radius of the system. This suggests that high-frequency binary systems could be promising candidates for detecting the effects of this modified gravity theory.

Warm dense matter (WDM) plays an important role in astrophysical objects and technological applications, but the rigorous diagnostics of corresponding experiments is notoriously difficult. In this work, we present a model-free analysis of x-ray Thomson scattering (XRTS) measurements at multiple scattering angles. Specifically, we analyze scattering data that have been collected for isochorically heated graphite at the Linac Coherent Light Source (LCLS). Overall, we find good consistency in the extracted temperature between small and large scattering angles, whereas possible signatures of non-equilibrium may be hidden by the source function, and by the available dynamic spectral range. The present proof-of-principle study directly points to improved experimental set-ups for equation-of-state measurements and for the model-free study of relaxation times.

In this study, we investigate gravitational lensing within modified gravity frameworks, focusing on the Hu-Sawicki $f(R)$ and normal branch Dvali-Gabadadze-Porrati (nDGP) models, and we compare these results with those obtained from general relativity (GR). Our results reveal that both modified gravity models consistently enhance key lensing parameters relative to GR, including the Einstein radius, lensing optical depth, and time delays. Notably, we find that the Hu-Sawicki $f(R)$ and nDGP models yield significantly larger Einstein radii and higher lensing probabilities, especially at greater redshifts, indicating an increased likelihood of lensing events under modified gravity. Our analysis of time delays further shows that the broader mass distributions in these frameworks lead to pronounced differences in high-mass lens systems, providing potential observational markers of modified gravity. Additionally, we observe amplified magnification factors in wave optics regimes, highlighting the potential for gravitational wave (GW) lensing to differentiate modified gravity effects from GR predictions. Through these findings, we propose modified gravity theories as compelling alternatives to GR in explaining cosmic phenomena, with promising implications for future high-precision gravitational lensing surveys.

We explore a comprehensive analysis of the formalism governing the gravitational field equations in degenerate higher-order scalar-tensor theories. The propagation of these theories in the vacuum has a maximum of three degrees of freedom and is at most quadratic in the second derivative of the scalar field. We investigate the gravitational field equation for spherically symmetric anisotropic matter content along with its non-conserved equations. Our analysis focuses on the evaluation of structure scalars to assess their behavior under Einstein's modification. We present a realistic mass contribution that sheds light on both geometric mass and total energy budget evaluations for celestial objects. Ultimately, we discuss two viable models restricted as minimal complexity and conformal flatness to enhance the scientific contribution of the present manuscript.

A covariant relativistic approach based on the Vlasov equation is applied to the study of infinite asymmetric nuclear matter. We use several Walecka-type hadronic models and obtain the dispersion relations for the longitudinal modes. The isovector and isoscalar collective modes are determined for a wide range of densities as a function of isospin asymmetry and momentum transfer within a set of eleven relativistic mean field models with different nuclear matter properties. Special attention is given to beta-equilibrium matter. It is shown that the possible propagation of isoscalar and isovector-like modes depends directly on the density dependence of the symmetric nuclear matter equation of state and of the symmetry energy, with a stiff equation of state favouring the propagation of isoscalar like collective modes at high densities, and a stiff symmetry energy defining the behavior of the isovector like modes which propagate for densities below two times saturation density. The coupling of the nuclear modes to the electron plasmon is also discussed.

We demonstrate an end-to-end technique for observing and characterizing massive black hole binary signals before they merge with the LISA space-based gravitational-wave observatory. Our method uses a zero-latency whitening filter, originally designed for rapidly observing compact binary mergers in ground-based observatories, to be able to observe signals with no additional latency due to filter length. We show that with minimal computational cost, we are able to reliably observe signals as early as 14 days premerger as long as the signal has accrued a signal-to-noise ratio of at least 8 in the LISA data. We also demonstrate that this method can be used to characterize the source properties, providing early estimates of the source's merger time, chirp mass, and sky localization. Early observation and characterization of massive black holes is crucial to enable the possibility of rapid multimessenger observations, and to ensure that LISA can enter a protected operating period when the merger signal arrives.

In a multi-field/fluid cosmological system consisting of a number of minimally coupled canonical scalar fields, non-canonical scalar fields and barotropic perfect fluids, we introduce a new definition of effective speed of sound of the entire system for describing the evolution of cosmological perturbations. This effective speed of sound is not just gauge invariant but also a background dependent quantity and therefore can be treated as a parameter to quantify perturbations in such multi-field/fluid systems. It is with this effective speed that the gauge invariant Bardeen potential and the curvature perturbation propagate at scales much smaller than the sound horizon. Further, the effective speed of sound defined in this paper generalizes the one defined by Garriga and Mukhanov for a single non-canonical scalar field to a system consisting of many minimally coupled barotropic perfect fluids, canonical and non-canonical scalar fields. Moreover, just like in the case of a single pure-kinetic non-canonical scalar field, this effective speed of the sound of the total system turns out to be identically equal to the total adiabatic speed of sound when the dynamic of the universe is driven by a number of pure kinetic non-canonical scalar fields making such a system tantamount to a system of equivalent multi barotropic perfect fluids. We also derive a set of equations which governs the evolution of perturbations in a general multi-field/fluid universe containing barotropic perfect fluids, canonical and non-canonical scalar fields. Using these equations we show that, in the large scale limit ($k = 0$ scales), if the perturbations are initially adiabatic, then it continues to remain so at that scales throughout the evolution of the universe. Consequently, at that scales, such multi-field/fluid universe dynamically behaves as if it contains only a single barotropic perfect fluid.

The nature of gravity can be tested by how gravitational waves (GWs) are emitted, detected, and propagate through the universe. Propagation tests are powerful, as small deviations compound over cosmological distances. However, GW propagation tests of theories beyond Einstein's general relativity (GR) are limited by the high degree of symmetry of the average cosmological spacetime. Deviations from homogeneity, i.e. gravitational lenses, allow for new interactions, e.g., between standard GW polarization and new scalar or vector fields, with different spin. Therefore, GW lensing beyond GR offers novel tests of cosmological gravity. Here we present the theory of GW propagation beyond GR in the short-wave expansion, including corrections to the leading-order amplitude and phase for the first time. As an example, we compute the dispersive (frequency-dependent) corrections to all metric and scalar field perturbations in Brans-Dicke, the simplest modified theory exhibiting GW dispersion. GW lensing effects are too small to observe in Brans-Dicke theories compatible with solar system and binary pulsar limits. Nevertheless, our formalism opens the possibility of novel tests of gravity, including dark-energy theories and screening mechanisms.