Papers for Tuesday, Dec 06 2022

From the Archean toward the Proterozoic, the Earth's atmosphere underwent a major shift from anoxic to oxic conditions, around 2.4 to 2.1 Gyr, known as the Great Oxidation Event (GOE). This rapid transition may be related to an atmospheric instability caused by the formation of the ozone layer. Previous works were all based on 1D photochemical models. Here, we revisit the GOE with a 3D photochemical-climate model to investigate the possible impact of the atmospheric circulation and the coupling between the climate and the dynamics of the oxidation. We show that the diurnal, seasonal and transport variations do not bring significant changes compared to 1D models. Nevertheless, we highlight a temperature dependence for atmospheric photochemical losses. A cooling during the late Archean could then have favored the triggering of the oxygenation. In addition, we show that the Huronian glaciations, which took place during the GOE, could have introduced a fluctuation in the evolution of the oxygen level. Finally, we show that the oxygen overshoot which is expected to have occurred just after the GOE, was likely accompanied by a methane overshoot. Such high methane concentrations could have had climatic consequences and could have played a role in the dynamics of the Huronian glaciations.

The distribution of gas and metals in the circumgalactic medium (CGM) plays a critical role in how galaxies evolve. The MUSE-ALMA Halos survey combines MUSE, ALMA and HST observations to constrain the properties of the multi-phase gas in the CGM and the galaxies associated with the gas probed in absorption. In this paper, we analyse the properties of galaxies associated with 32 strong \ion{H}{i} Ly-$\alpha$ absorbers at redshift $0.2 \lesssim z \lesssim 1.4$. We detect 79 galaxies within $\pm 500$ \kms \!of the absorbers in our 19 MUSE fields. These associated galaxies are found at physical distances from 5.7 kpc and reach star-formation rates as low as $0.1$ \Moyr. The significant number of associated galaxies allows us to map their physical distribution on the $\Delta v$ and $b$ plane. Building on previous studies, we examine the physical and nebular properties of these associated galaxies and find the following: i) 27/32 absorbers have galaxy counterparts and more than 50 per cent of the absorbers have two or more associated galaxies, ii) the \ion{H}{i} column density of absorbers is anti-correlated with the impact parameter (scaled by virial radius) of the nearest galaxy as expected from simulations, iii) the metallicity of associated galaxies is typically larger than the absorber metallicity which decreases at larger impact parameters. It becomes clear that while strong \ion{H}{i} absorbers are typically associated with more than a single galaxy, we can use them to statistically map the gas and metal distribution in the CGM.

We study the physical drivers of slow molecular cloud mergers within a simulation of a Milky Way-like galaxy in the moving-mesh code Arepo, and determine the influence of these mergers on the mass distribution and star formation efficiency of the galactic cloud population. We find that 83 per cent of these mergers occur at a relative velocity below 5 km/s, and are associated with large-scale atomic gas flows, driven primarily by (1) expanding bubbles of hot, ionised gas caused by supernova explosions and (2) galactic rotation. The major effect of these mergers is to aggregate molecular mass into higher-mass clouds: mergers account for over 50 per cent of the molecular mass contained in clouds of mass M > 2 x 10^6 Msun. These high-mass clouds have higher densities, internal velocity dispersions and instantaneous star formation efficiencies than their unmerged, lower-mass precursors. As such, the mean instantaneous star formation efficiency in our simulated galaxy, with its merger rate of just 1 per cent of clouds per Myr, is 25 per cent higher than in a similar population of clouds containing no mergers.

We report the first star formation history study of the Milky Way's nuclear star cluster (NSC) that includes observational constraints from a large sample of stellar metallicity measurements. These metallicity measurements were obtained from recent surveys from Gemini and VLT of 770 late-type stars within the central 1.5 pc. These metallicity measurements, along with photometry and spectroscopically derived temperatures, are forward modeled with a Bayesian inference approach. Including metallicity measurements improves the overall fit quality, as the low-temperature red giants that were previously difficult to constrain are now accounted for, and the best fit favors a two-component model. The dominant component contains 93%$\pm$3% of the mass, is metal-rich ($\overline{[M/H]}\sim$0.45), and has an age of 5$^{+3}_{-2}$ Gyr, which is $\sim$3 Gyr younger than earlier studies with fixed (solar) metallicity; this younger age challenges co-evolutionary models in which the NSC and supermassive black holes formed simultaneously at early times. The minor population component has low metallicity ($\overline{[M/H]}\sim$ -1.1) and contains $\sim$7% of the stellar mass. The age of the minor component is uncertain (0.1 - 5 Gyr old). Using the estimated parameters, we infer the following NSC stellar remnant population (with $\sim$18% uncertainty): 1.5$\times$10$^5$ neutron stars, 2.5$\times$10$^5$ stellar mass black holes (BHs) and 2.2$\times$10$^4$ BH-BH binaries. These predictions result in 2-4 times fewer neutron stars compared to earlier predictions that assume solar metallicity, introducing a possible new path to understand the so-called "missing pulsar problem". Finally, we present updated predictions for the BH-BH merger rates (0.01-3 Gpc$^{-3}$yr$^{-1}$).

Photoionisation is one of the main mechanisms at work in the gaseous environment of bright astrophysical sources. Many information on the gas physics, chemistry and kinematics, as well as on the ionising source itself, can be gathered through optical to X-ray spectroscopy. While several public time equilibrium photoionisation codes are readily available and can be used to infer average gas properties at equilibrium, time-evolving photoionisation models have only very recently started to become available. They are needed when the ionising source varies faster than the typical gas equilibration timescale. Indeed, using equilibrium models to analyse spectra of non-equilibrium gas may lead to inaccurate results and prevents a solid assessment of the gas density, physics and geometry. We present our novel Time-Evolving PhotoIonisation Device (TEPID), which self-consistently solves time evolving photoionisation equations (thermal and ionisation balance) and follows the response of the gas to changes of the ionising source. The code can be applied to a variety of astrophysical scenarios and produces time-resolved gas absorption spectra to fit the data. To describe the main features of TEPID, we apply it to two dramatically different astrophysical scenarios: a typical ionised absorber observed in the X-ray spectra of Active Galactic Nuclei (e.g. Warm Absorbers and UFOs) and the circumburst environment of a Gamma-Ray Burst. In both cases, the gas energy and ionisation balances vary as a function of time, gas density and distance from the ionising source. Time evolving ionisation leads to unique ionisation patterns which cannot be reproduced by stationary codes when the gas is out of equilibrium. This demonstrates the need for codes such as TEPID in view of the up-coming high-resolution X-ray spectrometers onboard missions like XRISM or Athena.

Stellar feedback-driven outflows regulate the stellar formation and chemical enrichment of galaxies, yet the underlying dependence of mass outflow rate on galaxy properties remains largely unknown. We develop a simple yet comprehensive non-equilibrium chemical evolution model~(NE-CEM) to constrain the mass-loading factor $\eta$ of outflows using the metallicity-stellar mass-SFR relation observed by SDSS at $z{=}0$. Our NE-CEM predicts the chemical enrichment by explicitly tracking both the histories of star formation and mass-loading. After exploring the EAGLE simulation, we discover a compact yet flexible model that accurately describes the average star formation histories of galaxies. Applying a novel method of chemically measuring $\eta$ to EAGLE, we find $\eta$ can be parametrised by its dependence on stellar mass and specific SFR as $\log\eta\propto M_*^{\alpha}s{\mathrm{SFR}}^{\beta}$, with $\alpha{=}{-}0.12$ and $\beta{=}0.32$ in EAGLE. Our chemically-inferred $\eta$ agrees remarkably well with the kinematic measurements by Mitchell et al. After extensive tests with EAGLE, we apply an NE-CEM Bayesian analysis to the SDSS data, yielding a tight constraint of $\log(\eta/1.585)=0.731{\pm}0.002\times(M_*/10^{9.5}M_{\odot})^{-0.222\pm0.004} (s{\mathrm{SFR}}/10^{-9.5}yr^{-1})^{0.078\pm0.003}$, in good agreement with the down-the-barrel measurements. Our best-fitting NE-CEM not only accurately describes the metallicity-stellar mass-SFR relation at $z{=}0$, but also successfully reproduce the so-called "fundamental metallicity relation'' at higher redshifts. Our results reveal that different galaxies form stars and enrich their gas in a non-equilibrium but strikingly coherent fashion across cosmic time.

We use hydrodynamical cosmological simulations to test the differences between cold and self-interacting dark matter models (CDM and SIDM) in the mass range of massive galaxies ($10^{12}M_{\odot}h^{-1}<M<10^{13.5}M_{\odot}h^{-1}$). We consider two SIDM models: one with constant cross section $\sigma/m_{\chi}=1\mathrm{cm^2g^{-1}}$ and one where the cross section is velocity-dependent. We analyse the halo density profiles and concentrations, comparing the predictions of dark-matter-only and hydrodynamical simulations in all scenarios. We calculate the best-fit Einasto profiles and compare the resulting parameters with previous studies and define the best-fit concentration-mass relations. We find that the inclusion of baryons reduces the differences between different dark matter models with respect to the DM-only case. In SIDM hydro runs, deviations from the CDM density profiles weakly depend on mass: the most massive systems ($M>10^{13}M_{\odot}h^{-1}$) show cored profiles, while the least massive ones ($M<10^{12.5}M_{\odot}h^{-1}$) have cuspier profiles. Finally, we compare the predictions of our simulations to observational results, by looking at the dark matter fractions and the distribution of strong lensing Einstein radii. We find that in SIDM the DM-fractions decrease more rapidly with increasing stellar mass than in CDM, leading to lower fractions at $M_{*}>10^{11}M_{\odot}$, a distinctive signature of SIDM. At the same time, the distribution of Einstein radii, derived from both CDM and SIDM hydro runs, is comparable to observed samples of strong lenses with $M>10^{13}M_{\odot}h^{-1}$. We conclude that the interplay between self-interaction and baryons can greatly reduce the expected differences between CDM and SIDM models at this mass scale, and that techniques able to separate the dark and luminous mass in the inner regions of galaxies are needed to constrain self-interactions.

Barnard's Loop is a famous arc of H$\alpha$ emission located in the Orion star-forming region. Here, we provide evidence of a possible formation mechanism for Barnard's Loop and compare our results with recent work suggesting a major feedback event occurred in the region around 6 Myr ago. We present a 3D model of the large-scale Orion region, indicating coherent, radial, 3D expansion of the OBP-Near/Brice\~{n}o-1 (OBP-B1) cluster in the middle of a large dust cavity. The large-scale gas in the region also appears to be expanding from a central point, originally proposed to be Orion X. OBP-B1 appears to serve as another possible center, and we evaluate whether Orion X or OBP-B1 is more likely to be the cause of the expansion. We find that neither cluster served as the single expansion center, but rather a combination of feedback from both likely propelled the expansion. Recent 3D dust maps are used to characterize the 3D topology of the entire region, which shows Barnard's Loop's correspondence with a large dust cavity around the OPB-B1 cluster. The molecular clouds Orion A, Orion B, and Orion $\lambda$ reside on the shell of this cavity. Simple estimates of gravitational effects from both stars and gas indicate that the expansion of this asymmetric cavity likely induced anisotropy in the kinematics of OBP-B1. We conclude that feedback from OBP-B1 has affected the structure of the Orion A, Orion B, and Orion $\lambda$ molecular clouds and may have played a major role in the formation of Barnard's Loop.

We discuss studies of polarization in astrophysical masers with particular emphasis on the case where the Zeeman splitting is small compared to the Doppler profile, resulting in a blend of the transitions between magnetic substates. A semi-classical theory of the molecular response is derived, and coupled to radiative transfer solutions for 1 and 2-beam linear masers, resulting in a set of non-linear, algebraic equations for elements of the molecular density matrix. The new code, PRISM, implements numerical methods to compute these solutions. Using PRISM, we demonstrate a smooth transfer between this case and that of wider splitting. For a J=1-0 system, with parameters based on the $v=1, J=1-0$ transition of SiO, we investigate the behaviour of linear and circular polarization as a function of the angle between the propagation axis and the magnetic field, and with the optical depth, or saturation state, of the model. We demonstrate how solutions are modified by the presence of Faraday rotation, generated by various abundances of free electrons, and that strong Faraday rotation leads to additional angles where Stokes-Q changes sign. We compare our results to a number of previous models, from the analytical limits derived by Goldreich, Keeley and Kwan in 1973, through computational results by W. Watson and co-authors, to the recent work by Lankhaar and Vlemmings in 2019. We find that our results are generally consistent with those of other authors given the differences of approach and the approximations made.

The recent development of $\theta-\theta$ techniques in pulsar scintillometry has opened the door for new high resolution imaging techniques of the scattering medium. By solving the phase retrieval problem and recovering the wavefield from a pulsar dynamic spectrum, the Doppler shift, time delay, and phase offset of individual images can be determined. However, the results of phase retrieval from a single dish are only know up to a constant phase rotation, which prevents their use for astrometry using Very Long Baseline Interferometry. We present an extension to previous $\theta-\theta$ methods using the interferometric visibilities between multiple stations to calibrate the wavefields. When applied to existing data for PSR B0834+06 we measure the effective screen distance and lens orientation with five times greater precision than previous works.

We present panco2, an open-source Python library designed to extract galaxy cluster pressure profiles from maps of the thermal Sunyaev-Zeldovich effect. The extraction is based on forward modeling of the total observed signal, allowing to take into account usual features of millimeter observations, such as beam smearing, data processing filtering, and point source contamination. panco2 offers a large flexibility in the inputs that can be handled and in the analysis options, enabling refined analyses and studies of systematic effects. We detail the functionalities of the code, the algorithm used to infer pressure profile measurements, and the typical data products. We present examples of running sequences, and the validation on simulated inputs. The code is available on GitHub at https://github.com/fkeruzore/panco2, and comes with an extensive technical documentation to complement this paper at https://panco2.readthedocs.io.

We present a procedure designed to standardize input received during faculty searches with the goal of amplifying student voices. The framework was originally used to collect feedback from graduate students, but it can be adapted easily to collect feedback from undergraduate students, faculty, staff or other stakeholders. Implementing this framework requires agreement across participating parties and minimal organization prior to the start of faculty candidate visits.

Feedback from massive stars plays an important role in the formation of star clusters. Whether a very massive star is born early or late in the cluster formation timeline has profound implications for the star cluster formation and assembly processes. We carry out a controlled experiment to characterize the effects of early forming massive stars on star cluster formation. We use the star formation software suite $\texttt{Torch}$, combining self-gravitating magnetohydrodynamics, ray-tracing radiative transfer, $N$-body dynamics, and stellar feedback to model four initially identical $10^4$ M$_\odot$ giant molecular clouds with a Gaussian density profile peaking at $521.5 \mbox{ cm}^{-3}$. Using the $\texttt{Torch}$ software suite through the $\texttt{AMUSE}$ framework we modify three of the models to ensure that the first star that forms is very massive (50, 70, 100 M$_\odot$). Early forming massive stars disrupt the natal gas structure, resulting in fast evacuation of the gas from the star forming region. The star formation rate is suppressed, reducing the total mass of stars formed. Our fiducial control model without an early massive star has a larger star formation rate and efficiency by up to a factor of three compared to the other models. Early forming massive stars promote the buildup of spatially separate and gravitationally unbound subclusters, while the control model forms a single massive cluster.

We describe a search for gravitational waves from compact binaries with at least one component with mass 0.2 $M_\odot$ -- $1.0 M_\odot$ and mass ratio $q \geq 0.1$ in Advanced LIGO and Advanced Virgo data collected between 1 November 2019, 15:00 UTC and 27 March 2020, 17:00 UTC. No signals were detected. The most significant candidate has a false alarm rate of 0.2 $\mathrm{yr}^{-1}$. We estimate the sensitivity of our search over the entirety of Advanced LIGO's and Advanced Virgo's third observing run, and present the most stringent limits to date on the merger rate of binary black holes with at least one subsolar-mass component. We use the upper limits to constrain two fiducial scenarios that could produce subsolar-mass black holes: primordial black holes (PBH) and a model of dissipative dark matter. The PBH model uses recent prescriptions for the merger rate of PBH binaries that include a rate suppression factor to effectively account for PBH early binary disruptions. If the PBHs are monochromatically distributed, we can exclude a dark matter fraction in PBHs $f_\mathrm{PBH} \gtrsim 0.6$ (at 90% confidence) in the probed subsolar-mass range. However, if we allow for broad PBH mass distributions we are unable to rule out $f_\mathrm{PBH} = 1$. For the dissipative model, where the dark matter has chemistry that allows a small fraction to cool and collapse into black holes, we find an upper bound $f_{\mathrm{DBH}} < 10^{-5}$ on the fraction of atomic dark matter collapsed into black holes.

We provide a brief, and inevitably incomplete overview of the use of Machine Learning (ML) and other AI methods in astronomy, astrophysics, and cosmology. Astronomy entered the big data era with the first digital sky surveys in the early 1990s and the resulting Terascale data sets, which required automating of many data processing and analysis tasks, for example the star-galaxy separation, with billions of feature vectors in hundreds of dimensions. The exponential data growth continued, with the rise of synoptic sky surveys and the Time Domain Astronomy, with the resulting Petascale data streams and the need for a real-time processing, classification, and decision making. A broad variety of classification and clustering methods have been applied for these tasks, and this remains a very active area of research. Over the past decade we have seen an exponential growth of the astronomical literature involving a variety of ML/AI applications of an ever increasing complexity and sophistication. ML and AI are now a standard part of the astronomical toolkit. As the data complexity continues to increase, we anticipate further advances leading towards a collaborative human-AI discovery.

UHECR propagation in a turbulent intergalactic magnetic field in the small-angle scattering regime is well understood for propagation distances much larger than the field coherence scale. The diffusion theory doesn't work and unexpected effects may appear for propagation over smaller distances, from a few and up to 10-20 coherence scales. We study the propagation of UHECRs in this regime, which may be relevant for intermediate mass UHECR nuclei and nG scale intergalactic magnetic fields with 1 Mpc coherence scale. We found that the trajectories form a non-trivial caustic-like pattern with strong deviation from isotropy. Thus, measurements of the flux from a source at a given distance will depend on the position of the observer.

We use PHANGS-JWST data to identify and classify 1271 compact 21 $\mu$m sources in four nearby galaxies using MIRI F2100W data. We identify sources using a dendrogram-based algorithm, and we measure the background-subtracted flux densities for JWST bands from 2 $\mu$m to 21 $\mu$m. Using the SED in JWST as well as HST bands, plus ALMA and MUSE/VLT observations, we classify the sources by eye. Then we use this classification to define regions in color-color space, and so establish a quantitative framework for classifying sources. We identify 1085 sources as belonging to the ISM of the target galaxies with the remainder being dusty stars or background galaxies. These 21 $\mu$m sources are strongly spatially associated with HII regions ($>92\%$ of sources), while 74$\%$ of sources are coincident with a stellar association defined in the HST data. Using SED fitting, we find that the stellar masses of the 21 $\mu$m sources span a range of 10$^{2}$ to 10$^{4}~M_\odot$ with mass-weighted ages down to 2 Myr. There is a tight correlation between attenuation-corrected H$\alpha$ and 21 $\mu$m luminosity for $L_{\nu,\mathrm{F2100W}}>10^{19}~\mathrm{W~Hz}^{-1}$. Young embedded source candidates selected at 21 $\mu$m are found below this threshold and have $M_\star < 10^{3}~M_\odot$.

We examine radiation and its effects on accretion disks orbiting astrophysical black holes. These disks are thermally radiating and can be geometrically and optically thin or thick. In this first paper of the series, we discuss the physics and the formulation required for this study. Subsequently, we construct and solve the relativistic radiative transfer equation, or find suitable solutions where that is not possible. We continue by presenting some of the accretion disks we considered for this work. We then describe the families of codes developed in order to study particle trajectories in strong gravity, calculate radiation forces exerted onto the disk material, and generate observation pictures of black hole systems at infinity. Furthermore, we also examine the veracity and accuracy of our work. Finally, we investigate how we can further use our results to estimate the black hole spin and the motion of disk material subjected to these radiation forces.

We present the study of arcsecond scale radio continuum and OH line emission of a sample of known OH megamaser galaxies with $z \geq$ 0.15 using archival Very Large Array (VLA) data. And also the results of our pilot Five hundred meter aperture spherical radio telescope (FAST) observations of 12 of these OHM galaxies. The arcsecond-scale resolution images show that the OH emission is distributed in one compact structure and spatially associated with radio continuum emission. Furthermore, nearly all the fitted components are likely smaller than the beam size ($\sim$ 1.4"), which indicates that the broad OH line profiles of these sources originated from one masing region or that more components are distributed in sub-arcsec scales. The radio parameters, including brightness temperature, spectral index, and q-index, show no significant differences with the low-redshift OHM galaxies, which have significantly lower OH line luminosities. Because these parameters are indicators of the central power sources (AGN, starburst, or both), our results indicate that the presence of radio AGN in the nuclei may not be essential for the formation of OH emission. Over 1/3 of OHMs in this sample (6/17) show possible variable features likely caused by interstellar scintillation due to small angular sizes. We might underestimate this value because these sources are associated with this sample's highest OH line flux densities. Those with low OH line flux densities might need higher sensitivity observations to study the variabilities. These results support the compact nature of OH maser emission and a starburst origin for the OHMs in our selected sample.

Aims. We perform a statistical study of the relations between the properties of solar energetic electron (SEE) events measured by the MESSENGER mission from 2010 to 2015 and the parameters of the respective parent solar activity phenomena to identify the potential correlations between them. During the time of analysis MESSENGER heliocentric distance varied between 0.31 and 0.47 au. Conclusions. (1) In this particular sample of events, with a majority of SEE events being widespread in heliolongitude and displaying relativistic electron intensity enhancements, a shock-related acceleration mechanism might be more relevant than a flare-related process in the acceleration of near-relativistic electrons. This result is mainly based on the stronger and more significant correlation found between the SEE peak intensities and the shock speed in comparison to the flare intensity; and on the asymmetry to the east of the range of connection angles (CAs) for which the SEE events present higher peak intensities and higher correlations with the solar activity, which might be related to the evolution of the magnetic field connection to the shock front. We note that the CA is the angular distance between the footpoint of the magnetic field connecting to the spacecraft and the longitude of the source region. (2) The correlations between the peak intensity of the SEE event and the shock speed or the flare intensity are stronger than in previous studies using measurements by spacecraft near 1 au.

We review the main experimental evidences on ultra high energy cosmic rays and their implications in the physics of these extremely energetic particles, also in connection with dark matter and cosmology. We discuss the basis of theoretical models aiming at explaining observations, highlighting the most relevant open questions in this fascinating field of research.

The environment of the high-redshift (z=1.408), powerful radio-loud galaxy 3C 297 has several distinctive features of a galaxy cluster. Among them, a characteristic halo of hot gas revealed by Chandra X-ray observations. In addition, a radio map obtained with the Very Large Array (VLA) shows a bright hotspot in the northwestern direction, created by the interaction of the AGN jet arising from 3C 297 with its environment. In the X-ray images, emission cospatial with the northwestern radio lobe is detected, and peaks at the position of the radio hotspot. The extended, complex X-ray emission observed with our new Chandra data is largely unrelated to its radio structure. Despite having attributes of a galaxy cluster, no companion galaxies have been identified from 39 new spectra of neighboring targets of 3C 297 obtained with the Gemini Multi-Object Spectrograph. None of the 19 galaxies for which a redshift was determined lies at the same distance as 3C 297. The optical spectral analysis of the new Gemini spectrum of 3C 297 reveals an isolated Type-II radio-loud AGN. We also detected line broadening in [O II](3728) with a FWHM about 1700 km/s and possible line shifts of up to 500-600 km/s. We postulate that the host galaxy of 3C 297 is a fossil group, in which most of the stellar mass has merged into a single object, leaving behind an X-ray halo.

In order to extract information about inflationary gravitational waves using $B$-mode patterns of cosmic microwave polarization anisotropy, we need to remove the foreground radiation from the Milky Way. In our previous delta-map method for foreground removal, the number of observation bands is limited to the number of parameters of the assumed foreground model, and therefore it was difficult to improve the sensitivity by increasing the number of observation bands. Here, we extend the previous method so that it can be adapted to an arbitrary number of observation bands. Using parametric likelihood and realistic foreground and CMB simulations, we show that our method can increase the sensitivity to the tensor-to-scalar ratio $r$ without inducing any significant bias.

In this work, we have studied the variability and frequency of occurrence of the grand minima using kinematic dynamo models of one solar mass star with different rotation rates and depths of convection zones. We specify the large-scale flows (differential rotations and meridional circulations) from corresponding hydrodynamic models. We include stochastic fluctuations in the Babcock-Leighton source for the poloidal field to produce variable stellar cycles. We observe that the rapidly rotating stars produce highly irregular cycles with strong magnetic fields and rarely produce Maunder-like grand minima, whereas the slowly rotating stars (Sun and longer rotation period) produce smooth cycles of weaker strength and occasional grand minima. In general, the number of the grand minima increases with the decrease in rotation rate. These results can be explained by the fact that with the increase of rotation period, the supercriticality of the dynamo decreases, and the dynamo is more prone to produce extended grand minima in this regime.

Randomly oriented flattened spheroids have been used to describe a broad range of astrophysical phenomena. Here we use this geometric approach to derive equations representing lines of sight through quasar absorption clouds to constrain cloud sizes.

In the past few years, the Event Horizon Telescope (EHT) has provided the first-ever event horizon-scale images of the supermassive black holes (BHs) M87* and Sagittarius A* (Sgr A*). The next-generation EHT project is an extension of the EHT array that promises larger angular resolution and higher sensitivity to the dim, extended flux around the central ring-like structure, possibly connecting the accretion flow and the jet. The ngEHT Analysis Challenges aim to understand the science extractability from synthetic images and movies so as to inform the ngEHT array design and analysis algorithm development. In this work, we take a look at the numerical fluid simulations used to construct the source models in the challenge set, which currently target M87* and Sgr A*. We have a rich set of models encompassing steady-state radiatively-inefficient accretion flows with time-dependent shearing hotspots, radiative and non-radiative general relativistic magneto-hydrodynamic simulations that incorporate electron heating and cooling. We find that the models exhibit remarkably similar temporal and spatial properties, except for the electron temperature since radiative losses substantially cool down electrons near the BH and the jet sheath. We restrict ourselves to standard torus accretion flows, and leave larger explorations of alternate accretion models to future work.

Galactic cosmic rays are mostly made up of energetic nuclei, with less than $1\%$ of electrons (and positrons). Precise measurement of the electron and positron component requires a very efficient method to reject the nuclei background, mainly protons. In this work, we develop an unsupervised machine learning method to identify electrons and positrons from cosmic ray protons for the Dark Matter Particle Explorer (DAMPE) experiment. Compared with the supervised learning method used in the DAMPE experiment, this unsupervised method relies solely on real data except for the background estimation process. As a result, it could effectively reduce the uncertainties from simulations. For three energy ranges of electrons and positrons, 80--128 GeV, 350--700 GeV, and 2--5 TeV, the residual background fractions in the electron sample are found to be about (0.45 $\pm$ 0.02)$\%$, (0.52 $\pm$ 0.04)$\%$, and (10.55 $\pm$ 1.80)$\%$, and the background rejection power is about (6.21 $\pm$ 0.03) $\times$ $10^4$, (9.03 $\pm$ 0.05) $\times$ $10^4$, and (3.06 $\pm$ 0.32) $\times$ $10^4$, respectively. This method gives a higher background rejection power in all energy ranges than the traditional morphological parameterization method and reaches comparable background rejection performance compared with supervised machine learning~methods.

Hadronic $\gamma$-ray sources associated with supernova remnants (SNRs) can serve as stopwatches for the escape of cosmic rays from SNRs, which gradually develops from highest-energy particles to lowest-energy particles with time. In this work, we analyze the 13.7~yr \emph{Fermi}-LAT data to investigate the $\gamma$-ray feature in/around the SNR G298.6$-$0.0 region. With $\gamma$-ray spatial analyses, we detect three point-like components. Among them, Src-NE is at the eastern SNR shell, and Src-NW is adjacent to the western edge of this SNR. Src-NE and Src-NW demonstrate spectral breaks at energies around/below 1.8~GeV, suggesting an old SNR age of $>$10~kyr. We also look into the X-ray emission from the G298.6$-$0.0 region, with the Chandra-ACIS data. We detected an extended keV source having a centrally filled structure inside the radio shell. The X-ray spectra are well fit by a model which assumes a collisional ionisation equilibrium of the thermal plasma, further supporting an old SNR age. Based on our analyses of the NANTEN CO- and ATCA-Parkes HI-line data, we determined a kinematic distance of $\sim$10.1~kpc from us to G298.6$-$0.0. This distance entails a large physical radius of the SNR of $\sim$15.5~pc, which is an additional evidence for an old age of $>$10~kyr. Besides, the CO data cube enables us to three-dimensionally locate the molecular clouds (MCs) which are potentially interacting with SNR G298.6$-$0.0 and could account for the hadronic $\gamma$-rays detected at Src-NE or Src-NW. Furthermore, the multiwavelength observational properties unanimously imply that the SNR--MC interaction occurs mainly in the northeast direction.

The review is devoted to the Radcliffe Wave recently discovered by Alves et al. from the analysis of molecular clouds. These authors singled out a narrow chain of molecular clouds, elongated almost in one line, located at an inclination of about 30$^o$ to the galactic axis y. The Radcliffe Wave itself describes damped vertical oscillations of molecular clouds with a maximum oscillation amplitude of about 160 pc and a characteristic wavelength of about 2.5 kpc. To date, the presence of the Radcliffe Wave has been confirmed in the vertical distribution of a) interstellar dust, b) sources of maser radiation and radio stars, which are very young stars and protostars closely associated with molecular clouds, c) low-mass stars of the T Tau type, d) more massive OB stars and e) young open clusters of stars. The Radcliffe Wave is also traced in the vertical velocities of young stars. Most of the considered results of the analysis of the vertical velocities of various young stars show that the oscillations of the vertical positions and vertical velocities of stars in the Radcliffe Wave occur synchronously. The nature of the Radcliffe Wave is completely unclear. The majority of researchers associate its occurrence with the assumption of an external gravitational impact on the galactic disk of a striker such as a dwarf satellite galaxy of the Milky Way.

The SKA PAthfinder Radio Continuum Surveys (SPARCS) are providing deep-field imaging of the faint (sub-mJy) extra-galactic radio source populations through a series of reference surveys. One of the key science goals for SPARCS is to characterize the relative contribution of radio emission associated with AGN from star-formation (SF) in these faint radio source populations, using a combination of high sensitivity and high angular resolution imaging over a range of spatial scales (arcsec to mas). To isolate AGN contribution from SF, we hypothesise that there exists a brightness temperature cut-off point separating pure AGN from SF. We present a multi-resolution (10-100 mas) view of the transition between compact AGN and diffuse SF through a deep wide-field EVN+e-MERLIN, multiple phase centre survey of the centre of the Northern SPARCS (SLOAN) reference field at 1.6 GHz. This is the first (and only) VLBI (+e-MERLIN) milliarcsecond angular resolution observation of this field, and of the wider SPARCS reference field programme. Using these high spatial resolution (9 pc - 0.3 kpc at z ~ 1.25) data, 11 milliarcsecond-scale sources are detected from a targeted sample of 52 known radio sources from previous observations with the e-MERLIN, giving a VLBI detection fraction of ~ 21%. At spatial scales of ~ 9 pc, these sources show little to no jet structure whilst at ~ 0.3 kpc one-sided and two-sided radio jets begin to emerge on the same sources, indicating a possible transition from pure AGN emissions to AGN and star-formation systems.

In this work, for the first time, we use seismic data as well as surface abundances to model the supergiant $\alpha$-Ori, with the goal of setting an upper bound on the axion-photon coupling constant $g_{a\gamma}$. We found that, in general, the stellar models with $g_{a \gamma} \in [0.002;2.0]\times 10^{-10}{\rm GeV}^{-1}$ agree with observational data, but beyond that upper limit, we did not find stellar models compatible with the observational constraints, and current literature. From $g_{a \gamma} = 3.5 \times 10^{-10} {\rm GeV}^{-1}$ on, the algorithm did not find any fitting model. Nevertheless, all axionic models considered, presented a distinct internal profile from the reference case, without axions. Moreover, as axion energy losses become more significant, the behaviour of the stellar models becomes more diversified, even with very similar input parameters. Nonetheless, the consecutive increments of $g_{a \gamma}$ still show systematic tendencies, resulting from the axion energy losses. Moreover, we establish three important conclusions: (1) The increased luminosity and higher neutrino production are measurable effects, possibly associated with axion energy losses. (2) Stellar models with axion energy loss show a quite distinct internal structure. (3) The importance of future asteroseismic missions in observing low-degree non-radial modes in massive stars:internal gravity waves probe the near-core regions, where axion effects are most intense. Thus, more seismic data will allow us to constrain $g_{a\gamma}$ better and prove or dismiss the existence of axion energy loss inside massive stars.

The study of galaxy evolution hinges on our ability to interpret multi-wavelength galaxy observations in terms of their physical properties. To do this, we rely on spectral energy distribution (SED) models which allow us to infer physical parameters from spectrophotometric data. In recent years, thanks to the wide and deep multi-waveband galaxy surveys, the volume of high quality data have significantly increased. Alongside the increased data, algorithms performing SED fitting have improved, including better modeling prescriptions, newer templates, and more extensive sampling in wavelength space. We present a comprehensive analysis of different SED fitting codes including their methods and output with the aim of measuring the uncertainties caused by the modeling assumptions. We apply fourteen of the most commonly used SED fitting codes on samples from the CANDELS photometric catalogs at z~1 and z~3. We find agreement on the stellar mass, while we observe some discrepancies in the star formation rate (SFR) and dust attenuation results. To explore the differences and biases among the codes, we explore the impact of the various modeling assumptions as they are set in the codes (e.g., star formation histories, nebular, dust, and AGN models) on the derived stellar masses, SFRs, and A_V values. We then assess the difference among the codes on the SFR-stellar mass relation and we measure the contribution to the uncertainties by the modeling choices (i.e., the modeling uncertainties) in stellar mass (~0.1dex), SFR (~0.3dex), and dust attenuation (~0.3mag). Finally, we present some resources summarizing best practices in SED fitting.

We develop a novel approach to measure dust attenuation properties of galaxies,including the dust opacity and shape of the attenuation curve in both optical and NUV, as well as the strength of the 2175{\AA} absorption feature. From an observed spectrum the method uses a model-independent approach to derive a relative attenuation curve.The absolute amplitude is then calibrated with the NIR photometry. The dust-corrected spectrum is fitted with stellar population models to derive the dust-free model spectrum covering the whole wavelength range from NUV to NIR and is compared with the observed SED/spectrum to determine dust attenuation properties. We apply this method to investigate dust attenuation on kpc scales, using a sample of 134 galaxies with the integral field spectroscopy from MaNGA, the NIR imaging from 2MASS, and the NUV imaging from Swift/UVOT. We find that the attenuation curves in regions of kpc scales span a wide range of slopes in both optical and UV. The slope is shallower at higher optical opacity, a trend that is held even when the sample is limited to narrow ranges of specific star formation rate (sSFR), minor-to-major axis ratio (b/a) and the location within individual galaxies. The 2175{\AA} bump in the attenuation curve at kpc scales presents a wide range of strength. The strength shows a strong negative correlation with the sSFR, but the correlations with the optical opacity, $b/a$ and the location within individual galaxies are all weak. All these trends appear to be independent of the stellar mass of galaxies, implying that the dust attenuation is regulated by local processes rather than by global properties of galaxies. Our results support the scenario that the variation of the 2175{\AA} bump is driven predominantly by processes related to star formation, such as destruction of small dust grains by UV radiation in star-forming regions.

I present general analytic expressions for distance calculations (comoving distance, time coordinate, and absorption distance) in the standard $\Lambda$CDM cosmology, allowing for the presence of radiation and for non-zero curvature. The solutions utilise the symmetric Carlson basis of elliptic integrals, which can be evaluated with fast numerical algorithms that allow trivial parallelisation on GPUs and automatic differentiation without the need for additional special functions. I introduce a PyTorch-based implementation in the phytorch.cosmology package and briefly examine its accuracy and speed in comparison with numerical integration and other known expressions (for special cases). Finally, I demonstrate an application to high-dimensional Bayesian analysis that utilises automatic differentiation through the distance calculations to efficiently derive posteriors for cosmological parameters from up to $10^6$ mock type Ia supernovae using variational inference.

The dynamics of the Universe is analyzed using an exponential function for the dark energy equation of state, known as Gong-Zhang parameterization. The phase space of the free parameters presented in the model is constrained using Cosmic Microwave Background radiation, Cosmic Chronometers, modulus distance from Hydrogen II Galaxies, Type Ia Supernovae and measurements from Baryon Acoustic Oscillations, together with a stronger bound from a Joint analysis. The cosmological model is confronted with $\Lambda$CDM, observing there is a strong evidence for $\Lambda$CDM in the Joint analysis although the exponential model is preferred when the data are separated. Based on the Joint analysis, a value of $\omega_0 = -1.202^{+0.027}_{-0.026}$ is found for the characteristic parameter presented in the equation of state. Additionally, the cosmographic parameters at current times are reported, having $q_0 = -0.789^{+0.034}_{-0.036}$, $j_0=1.779^{+0.130}_{-0.119}$, and a transition deceleration-acceleration redshift $z_T = 0.644^{+0.011}_{-0.012}$. Furthermore, the age of the Universe is estimated as $t_U = 13.788^{+0.019}_{-0.019}$ Gyrs. Finally, under the $\mathbf{\mathbb{H}}0(z)$ diagnostic, we discuss this model could alleviate the $H_0$ tension.

The ultra-light dark matter (ULDM) model has become a popular dark matter scenario nowadays. The mass of the ULDM particles is extremely small so that they can exhibit wave properties in the central dark matter halo region. Numerical simulations show that a soliton core with an almost constant mass density would be formed inside the ULDM halo. If our Galactic Centre has a dark matter soliton core, some of the stars orbiting about the supermassive black hole (Sgr A*) would be crossing the soliton core boundary. In this article, we report the first theoretical study on how the dark matter soliton core near the Sgr A* could affect the surrounding stellar orbital precession. We show that some particular stellar orbital precession may become retrograde in direction, which is opposite to the prograde direction predicted by General Relativity. We anticipate that future orbital data of the stars S2, S12 and S4716 can provide crucial tests for the ULDM model for $m \sim 10^{-19}-10^{-17}$ eV.

We present 850 $\mu$m dust polarization observations of the massive DR21 filament from the B-fields In STar-forming Region Observations (BISTRO) survey, using the POL-2 polarimeter and the SCUBA-2 camera on the James Clerk Maxwell Telescope. We detect ordered magnetic fields perpendicular to the parsec-scale ridge of the DR21 main filament. In the sub-filaments, the magnetic fields are mainly parallel to the filamentary structures and smoothly connect to the magnetic fields of the main filament. We compare the POL-2 and Planck dust polarization observations to study the magnetic field structures of the DR21 filament on 0.1--10 pc scales. The magnetic fields revealed in the Planck data are well aligned with those of the POL-2 data, indicating a smooth variation of magnetic fields from large to small scales. The plane-of-sky magnetic field strengths derived from angular dispersion functions of dust polarization are 0.6--1.0 mG in the DR21 filament and $\sim$ 0.1 mG in the surrounding ambient gas. The mass-to-flux ratios are found to be magnetically supercritical in the filament and slightly subcritical to nearly critical in the ambient gas. The alignment between column density structures and magnetic fields changes from random alignment in the low-density ambient gas probed by Planck to mostly perpendicular in the high-density main filament probed by JCMT. The magnetic field structures of the DR21 filament are in agreement with MHD simulations of a strongly magnetized medium, suggesting that magnetic fields play an important role in shaping the DR21 main filament and sub-filaments.

The X-ray afterglow of many gamma-ray bursts (GRBs) exhibits a plateau phase before the normal power-law decay stage, which may be related to continued activities of the central engine. Tang et al. 2019 collected 174 such GRBs and confirmed the so called $L-T-E$ correlation which involves three key parameters, i.e., the isotropic $\gamma$-ray energy $E_{\gamma,\rm iso}$ of the prompt phase, the end time $T_{a}$ of the plateau phase and the corresponding X-ray luminosity $L_{X}$. In this study, the $L-T-E$ correlation is confirmed and updated as $L_{X} \propto T_{a}^{-0.99} E_{\gamma ,\rm iso}^{0.86}$ with a large sample consisting of 210 plateau GRBs with known redshifts. The tight correlation is then applied to derive the pseudo redshift of other 130 plateau GRBs whose redshifts are not directly measured. Statistical analysis is also carried out on this pseudo redshift sample.

We present 250~GHz continuum and H29alpha line data toward W49N:A2, a hypercompact HII region ionized by an O9 star. The data obtained with ALMA at a resolution of ~0"05 (600 au) confirmed the presence of an ionized ring with a radius of~700 au inclined by ~50degree (0degree for pole-on). It has a width of ~1000 au and is relatively flat with a scale height of less than several hundred au. The tilted ring, or the apparent ellipse, has a prominent velocity difference between its NW and SE ridges along the minor axis, suggesting that it is expanding in the equatorial plane at a velocity of 13.2 km/s. The ring also shows a hint of rotation at 2.7 km/s, which is significantly (2.5sigma) smaller than the Kepler velocity of 5.2 km/s at its radius around the 20 M$_sun star. This can be interpreted that the ring gas has been transported from the radius of ~170 au by conserving its original specific angular momentum that it had there. The ionized ring may thus be a remnant of the accretion disk that fed the O9 star, whose radiation or magnetic activities became so strong that the disk accretion was reversed due to the intense thermal or magneto-hydrodynamic pressure around the star. The data has revealed a rare example of how a massive star terminates its accretion at the end of its formation, transforming a hypercompact HII region into an ultracompact HII region.

The interacting dark energy (IDE) model is a promising alternative cosmological model which has the potential to solve the fine-tuning and coincidence problems by considering the interaction between dark matter and dark energy. Previous studies have shown that the energy exchange between the dark sectors in this model can significantly affect the dark matter halo properties. In this study, utilising a large set of cosmological $N$-body simulations, we analyse the redshift evolution of the halo concentration - mass ($c$ - $M$) relation in the IDE model, and show that the $c$ - $M$ relation is a sensitive proxy of the interaction strength parameter $\xi_2$, especially at lower redshifts. Furthermore, we construct parametrized formulae to quantify the dependence of the $c$ - $M$ relation on $\xi_2$ at redshifts ranging from $z=0$ to $0.6$. Our parametrized formulae provide a useful tool in constraining $\xi_2$ with the observational $c$ - $M$ relation. As a first attempt, we use the data from X-ray, gravitational lensing, and galaxy rotational curve observations and obtain a tight constraint on $\xi_2$, i.e. $\xi_2 = 0.071 \pm 0.034$. Our work demonstrates that the halo $c$ - $M$ relation, which reflects the halo assembly history, is a powerful probe to constrain the IDE model.

The X-ray emission mechanism of powerful extragalactic jets, which has important implications for their environmental impact, is poorly understood. The X-ray/radio positional offsets in individual features of jets provide important clues. Extending the previous work in Reddy et al. 2021, we present a detailed comparison between X-ray maps deconvolved using the Low Count Image Reconstruction and Analysis (LIRA) tool and radio maps of 164 components from 77 Chandra-detected X-ray jets. We detect 94 offsets (57%), with 58 new detections. In FR II-type jet knots, the X-rays peak and decay before the radio in about half the cases, disagreeing with the predictions of one-zone models. While a similar number of knots lack statistically significant offsets, we argue that projection and distance effects result in offsets below the detection level. Similar de-projected offsets imply that X-rays could be more compact than radio for most knots, and we qualitatively reproduce this finding with a "moving-knot" model. The bulk Lorentz factor derived for knots under this model is consistent with previous radio-based estimates, suggesting kpc-scale jets are only mildly relativistic. An analysis of X-ray/radio flux ratio distributions does not support the commonly invoked mechanism of X-ray production from inverse Compton scattering of the cosmic microwave background but does show a marginally significant trend of declining flux ratio as a function of distance from the core. Our results imply the need for multi-zone models to explain the X-ray emission from powerful jets. We provide an interactive list of our X-ray jet samples at this http URL

We show that the Laser Interferometer Gravitational Wave Observatory (LIGO) is a powerful instrument in the Search for Extra-Terrestrial Intelligence (SETI). LIGO's ability to detect gravitational waves (GWs) from accelerating astrophysical sources, such as binary black holes, also provides the potential to detect extra-terrestrial mega-technology, such as Rapid And/or Massive Accelerating spacecraft (RAMAcraft). We show that LIGO is sensitive to RAMAcraft of $1$ Jupiter mass accelerating to a fraction of the speed of light (e.g. $10\%$) up to about $100\,{\rm kpc}$. Existing SETI searches probe on the order of thousands to tens of thousands of stars for human-scale technology (e.g. radiowaves), whereas LIGO can probe all $10^{11}$ stars in the Milky Way for RAMAcraft. Moreover, thanks to the $f^{-1}$ scaling of the GW signal produced by these sources, our sensitivity to these objects will increase as low-frequency, space-based detectors are developed and improved. In particular, we find that DECIGO and the Big Bang Observer (BBO) will be about 100 times more sensitive than LIGO, increasing the search volume by 10$^{6}$. In this paper, we calculate the waveforms for linearly accelerating RAMAcraft in a form suitable for LIGO, Virgo, or KAGRA searches and provide the range for a variety of possible masses and accelerations. We expect that the current and upcoming GW detectors will soon become an excellent complement to the existing SETI efforts.

The angular momentum of molecular cloud cores plays an essential role in the star formation process. However, the time evolution of the angular momentum of molecular cloud cores is still unclear. In this paper, we perform three-dimensional simulations to investigate the time evolution of the angular momentum of molecular cloud cores formed through filament fragmentation. As a result, we find that most of the cores rotate perpendicular to the filament axis. The mean angular momentum of the cores changes by only around 30% during the initial stage of their formation process and then remains almost constant. In addition, we analyze the internal angular momentum structure of the cores. Although the cores gain angular momentum with various directions from the initial turbulent velocity fluctuations of their parent filaments, the angular momentum profile in each core converges to the self-similar solution. We also show that the degree of complexity of the angular momentum structure in a core slightly decreases with time. Moreover, we perform synthetic observations and show that the angular momentum profile measured from the synthetic mean velocity map is compatible with the observations when the filament inclination is taken into account. The present study suggests a theory of core formation from filament fragmentation where the angular momentum structures of the cores are determined by the velocity fluctuation along the filaments and both are compatible with the observations. This theory also provides new insights on the core properties that could be observationally tested.

The Cherenkov Telescope Array (CTA) Observatory will be the next-generation ground-based very-high-energy gamma-ray observatory, sensitive from 20 GeV up to 300 TeV. The Large-Sized Telescope prototype (LST-1), currently in the commissioning phase, was inaugurated in October 2018 on La Palma (Spain). It is the first of four LST telescopes for CTA, to be built in La Palma. In 2021, LST-1 performed observations of one of the Galactic PeVatron candidates, LHAASO J2108+5157, recently discovered by the LHAASO collaboration. We present results of our analysis of the LST-1 data, putting strong constraints on the emission of the source in the multi-TeV band. We also present results of multi-wavelength modeling using 12-years Fermi-LAT data and Target of Opportunity observations with XMM-Newton. We test different scenarios for the parent particles producing the high energy emission and put constraints on their spectra.

Gamma-ray bursts (GRBs) are the most powerful explosions in the universe. The standard model invokes a relativistic fireball with a bright photosphere emission component. How efficiently the jet converts its energy to radiation is a long-standing problem and it is poorly constrained. A definitive diagnosis of GRB radiation components and measurement of GRB radiative efficiency requires prompt emission and afterglow data with high-resolution and wide-band coverage in time and energy. Here we report a comprehensive temporal and spectral analysis of the TeV-emitting bright GRB 190114C. Its fluence is one of the highest of all GRBs detected so far, which allows us to perform a high-resolution study of the prompt emission spectral properties and their temporal evolution down to a timescale of about 0.1 s. We observe that each of the initial pulses has a thermal component contributing $\sim20\%$ of the total energy, the corresponding temperature and the inferred Lorentz factor of the photosphere evolve following broken power-law shapes. From the observation of the non-thermal spectra and the light-curve, the onset of afterglow corresponding to the deceleration of the fireball is considered at $\sim 6$~s. By incorporating the thermal and the non-thermal observations, as well as the photosphere and the synchrotron radiative mechanisms, we can directly derive the fireball energy budget with little dependence on hypothetical parameters and to measure a $\sim 16\%$ radiative efficiency for this GRB. With the fireball energy budget derived, the afterglow microphysics parameters can also be constrained directly from the data.

Type U radio bursts are impulsive coherent radio emissions produced by the Sun that indicate the presence of subrelativistic electron beams propagating along magnetic loops in the solar corona. In this work, we present the analysis of a type U radio burst that was exceptionally imaged on 2011 March 22 by the Nan\c{c}ay Radioheliograph (NRH) at three different frequencies (298.7, 327.0, and 360.8 MHz). Using a novel modelling approach, we show for the first time that the use of high-resolution radio heliograph images of type U radio bursts can be sufficient to both accurately reconstruct the 3D morphology of coronal loops (without recurring to triangulation techniques) and to fully constrain their physical parameters. At the same time, we can obtain unique information on the dynamics of the accelerated electron beams, which provides important clues as to the plasma mechanisms involved in their acceleration and as to why type U radio bursts are not observed as frequently as type III radio bursts. We finally present plausible explanations for a problematic aspect related to the apparent lack of association between the modeled loop as inferred from radio images and the extreme-ultraviolet (EUV) structures observed from space in the same coronal region

Large coronal loops around one solar radius in altitude are an important connection between the solar wind and the low solar corona. However, their plasma properties are ill-defined as standard X-ray and UV techniques are not suited to these low-density environments. Diagnostics from type J solar radio bursts at frequencies above 10 MHz are ideally suited to understand these coronal loops. Despite this, J-bursts are less frequently studied than their type III cousins, in part because the curvature of the coronal loop makes them unsuited for using standard coronal density models. We used LOw-Frequency-ARray (LOFAR) and Parker Solar Probe (PSP) solar radio dynamic spectrum to identify 27 type III bursts and 27 J-bursts during a solar radio noise storm observed on 10 April 2019. We found that their exciter velocities were similar, implying a common acceleration region that injects electrons along open and closed magnetic structures. We describe a novel technique to estimate the density model in coronal loops from J-burst dynamic spectra, finding typical loop apex altitudes around 1.3 solar radius. At this altitude, the average scale heights were 0.36 solar radius, the average temperature was around 1 MK, the average pressure was 0.7 mdyn cm$^{-2}$, and the average minimum magnetic field strength was 0.13 G. We discuss how these parameters compare with much smaller coronal loops.

On Mars it is possible that after the recession of the seasonal polar ice cap, small icy patches left behind in shady places due to the low thermal conductivity of the Martian surface and atmosphere, are met by direct sunlight during the summer. These patches might warm up substantially and we analyzed below how could a liquid phase emerge in these places, surveying HiRISE images. 110 images were analyzed out of the available 1400 that fit the selection criteria of location and season, and we identified 37 images with smaller ice patches on them. Their separation from other bright patches, like clouds or lighter shades of layers and rocks were possible by their bluish color and strong connection to local topographic shading. These areas range between 140{\deg} and 200{\deg} solar longitude in the latitude band between -40{\deg} and -60{\deg}. The diameter of the ice patches ranges between 1.5-300 meters, and they remain on the surface even after the seasonal polar cap has passed over the area for the duration range of 19-133 martian days. With the help of The Mars Climate Database (MCD) we simulated the surface temperature and predicted CO2 and H2O ice cover at 22 analyzed areas. Judging by the models, the average noon temperature does not reach the melting point of water, which is 273 K, therefore the occurrence of liquid water on the macroscopic scale is highly unlikely, however there is a possibility that an interfacial premelting of ice (a few nanometers thick waterlayer) might form between the layered and the water ice.

The Maximum Eccentricity Method (MEM) is a standard tool for the analysis of planetary systems and their stability. The method amounts to estimating the maximal stretch of orbits over sampled domains of initial conditions. The present paper leverages on the MEM to introduce a sharp detector of separatrices and chaotic seas. After introducing the MEM analogue for nearly-integrable action-angle Hamiltonians, i.e., diameters, we use low-dimensional dynamical systems with multi-resonant modes and junctions, supporting chaotic motions, to recognise the drivers of the diameter metric. Once this is appreciated, we present a second-derivative based index measuring the regularity of this application. This quantity turns to be a sensitive and robust indicator to detect separatrices, resonant webs and chaotic seas. We discuss practical applications of this framework in the context of $N$-body simulations for the planetary case affected by mean-motion resonances, and demonstrate the ability of the index to distinguish minute structures of the phase space, otherwise undetected with the original MEM.

The Approximate Bayesian Computation (ABC) algorithm considers natural selection in biology as a guiding principle for statistical model selection and parameter estimation. We take this ABC approach to cosmology and use it to infer which model anchored on a choice of a Hubble constant prior would be preferred by the data. We find in all of our runs that the Planck Hubble constant ($H_0 = 67.4 \pm 0.5$ km s$^{-1}$Mpc$^{-1}$) always emerge naturally selected by the ABC over the SH$0$ES estimate ($H_0 = 73.30 \pm 1.04$ km s$^{-1}$Mpc$^{-1}$). The result holds regardless of how we mix our data sets, including supernovae, cosmic chronometers, baryon acoustic oscillations, and growth data. Compared with the traditional MCMC, we find that the ABC always results with narrower cosmological constraints, but remain consistent inside the corresponding MCMC posteriors.

In the submm regime, spectral line scans and line intensity mapping (LIM) are new promising probes for the cold gas content and star formation rate of galaxies across cosmic time. However, both of these two measurements suffer from field-to-field variance. We study the effect of field-to-field variance on the predicted CO and [CII] power spectra from future LIM experiments such as CONCERTO, as well as on the line luminosity functions (LFs) and the cosmic molecular gas mass density that are currently derived from spectral line scans. We combined a 117 $\rm deg^2$ dark matter lightcone from the Uchuu cosmological simulation with the simulated infrared dusty extragalactic sky (SIDES) approach. We find that in order to constrain the CO LF with an uncertainty below 20%, we need survey sizes of at least 0.1 $\rm deg^2$. Furthermore, accounting for the field-to-field variance using only the Poisson variance can underestimate the total variance by up to 80%. The lower the luminosity is and the larger the survey size is, the higher the level of underestimate. At $z$<3, the impact of field-to-field variance on the cosmic molecular gas density can be as high as 40% for the 4.6 arcmin$^2$ field, but drops below 10% for areas larger than 0.2 deg$^2$. However, at $z>3$ the variance decreases more slowly with survey size and for example drops below 10% for 1 deg$^2$ fields. Finally, we find that the CO and [CII] LIM power spectra can vary by up to 50% in $\rm 1 deg^2$ fields. This limits the accuracy of the constraints provided by the first 1 deg$^2$ surveys. The level of the shot noise power is always dominated by the sources that are just below the detection thresholds. We provide an analytical formula to estimate the field-to-field variance of current or future LIM experiments. The code and the full SIDES-Uchuu products (catalogs, cubes, and maps) are publicly available.

Gas giant planets are believed to accrete from their circumplanetary disks (CPDs). The CPDs usually involve accretion through the boundary layer (BL) in the vicinity of planets. Prior studies have concentrated on the BL of non-spinning planets. We investigate the influence of planetary spin on the wave behaviors within the BL. The rotation profile in such BLs would show sharp transition from the rigid rotation to the Keplerian rotation. We examine the angular momentum transport in these BL in terms of linear perturbation analysis. We find that the global inertia-acoustic mode associated with spinning planets would give rise to the inflow of angular momentum and the accretion of gas. In this work, we identify a new kind of global mode, namely the Rossby mode. The Rossby mode can lead to the outflow of angular momentum and the decretion of gas from a spinning planet. The Rossby mode provide a negative feedback that regulates the planetary spin and mass. We compare the growth rate of the two modes as a function of the width of BL, the Mach number and the spin rate of planet. Our results reveal the underlying hydrodynamic mechanism of terminal spins and asymptotic mass of the giant planets.

We study the optical variability of a sample of candidate low-mass (dwarf ang Seyfert) active galactic nuclei (AGNs) using Zwicky Transient Facility g-band light curves. Our sample is compiled from broad-line AGNs in dwarf galaxies reported in the literature with single-epoch virial black hole (BH) masses in the range $M_{\rm{BH}} \sim 10^{4}$--$10^{8}\ M_{\odot}$. We measure the characteristic ``damping'' timescale of the optical variability $\tau_{\rm{DRW}}$, beyond which the power spectral density flattens, of a final sample of 79 candidate low-mass AGNs with high-quality light curves. Our results provide further confirmation of the $M_{\rm{BH}} - \tau_{\rm{DRW}}$ relation from Burke et al. 2022 within $1\sigma$ agreement, adding 78 new low-mass AGNs to the relation. The agreement suggests that the virial BH mass estimates for these AGNs are generally reasonable. We expect that the optical light curve of an accreting intermediate-mass black hole (IMBH) to vary with a rest-frame damping timescale of $\sim$ tens of hours, which could enable detection and direct mass estimation of accreting IMBHs in wide-field time-domain imaging surveys with sufficient cadence like with the Vera C. Rubin Observatory.

We search for a linearity in the ratio of dark matter to baryonic matter as a function of radius for galaxy clusters, motivated by a recent result by Lovas (arXiv:2206.11431), who has discovered such a linearity for a diverse suite of galaxies in the SPARC sample. For our analysis, we used a sample of 54 non-cool core clusters from the HIFLUGCS sample. We do not find any evidence for a linear trend in the aforementioned ratio as a function of radius for individual clusters. We then repeat this analysis for the stacked sample, which also does not show this linearity. Therefore, the linear scaling found by Lovas is not a universal property of dark matter haloes at all scales.

The recent exquisite Gaia astrometric, photometric, and radial velocity (RV) measurements resulted in a substantial advancement for the determination of the orbits for old star clusters, including the oldest Milky Way globular clusters (MW GCs). The main goal of this paper is to use the Gaia DR3 and the VVVX measurements to obtain the orbits for nearly a dozen new Galactic GC candidates that have been poorly studied or previously unexplored. We use the Gaia DR3 and VVVX databases to identify bonafide members of the Galactic GC candidates: VVV-CL160, Patchick122, Patchick125, Patchick126, Kronberger99, Kronberger119, Kronberger143, ESO92-18, ESO93-08, Gaia2, and Ferrero54. The relevant mean cluster physical parameters are derived (distances, Galactic coordinates, proper motions, RVs). We measure accurate mean RVs for the GCs VVV-CL160 and Patchick126, using observations acquired at the Gemini-South telescope with the IGRINS high-resolution spectrograph. Orbits for each cluster are then computed using the GravPot16 model, assuming typical Galactic bar pattern speeds. We reconstruct the orbits for these clusters for the first time. These include star clusters with retrograde and prograde orbital motions, both in the Galactic bulge and disk. Orbital properties, such as the mean time-variations of perigalactic and apogalactic distances, eccentricities, vertical excursions from the Galactic plane, and Z-components of the angular momentum are obtained for our sample. Our main conclusion is that, based on the orbital parameters, Patchick125 and Patchick126 are genuine MW bulge/halo GCs; Ferrero54, Gaia2 and Patchick122 are MW disk GCs. The orbits of Kronberger99, Kronberger119, Kronberger143, ESO92-18, and ESO93-08 are more consistent with old MW disk open clusters. VVV-CL160 falls very close to the Galactic centre, but reaches larger distances beyond the Sun, thus its origin is still unclear.

Mini-EUSO (Multiwavelength Imaging New Instrument for the Extreme Universe Space Observatory) is a telescope observing the Earth from the International Space Station since 2019. The instrument employs a Fresnel-lens optical system and a focal surface composed of 36 multi-anode photomultiplier tubes, 64 channels each, for a total of 2304 channels with single photon counting sensitivity. Mini-EUSO also contains two ancillary cameras to complement measurements in the near infrared and visible ranges. The scientific objectives of the mission range from the search for extensive air showers generated by Ultra-High Energy Cosmic Rays (UHECRs) with energies above 10$^{21}$ eV, the search for nuclearites and Strange Quark Matter (SQM), up to the study of atmospheric phenomena such as Transient Luminous Events (TLEs), meteors and meteoroids. Mini-EUSO can map the night-time Earth in the near UV range (between 290-430 nm) with a spatial resolution of about 6.3 km (full field of view of 44{\deg}) and a maximum temporal resolution of 2.5 $\mu$s, observing our planet through a nadir-facing UV-transparent window in the Russian Zvezda module. The detector saves triggered transient phenomena with a sampling rate of 2.5 $\mu$s and 320 $\mu$s, as well as continuous acquisition at 40.96 ms scale. In this paper we discuss the detector response and the flat-fielding and calibration procedures. Using the 40.96 ms data, we present $\simeq$6.3 km resolution night-time Earth maps in the UV band, and report on various emissions of anthropogenic and natural origin. We measure ionospheric airglow emissions of dark moonless nights over the sea and ground, studying the effect of clouds, moonlight, and artificial (towns, boats) lights. In addition to paving the way forward for the study of long-term variations of natural and artificial light, we also estimate the observation live-time of future UHECR detectors.

Background. Astrometry at or below the micro-arcsec level with an imaging telescope assumes that the uncertainty on the location of an unresolved source can be an arbitrarily small fraction of the detector pixel, given a sufficient photon budget. Aim. This paper investigates the geometric limiting precision, in terms of CCD pixel fraction, achieved by a large set of star field images, selected among the publicly available science data of the TESS mission. Method. The statistics of the distance between selected bright stars ($G \simeq 5\,mag$), in pixel units, is evaluated, using the position estimate provided in the TESS light curve files. Results. The dispersion of coordinate differences appears to be affected by long term variation and noisy periods, at the level of $0.01$ pixel. The residuals with respect to low-pass filtered data (tracing the secular evolution), which are interpreted as the experimental astrometric noise, reach the level of a few milli-pixel or below, down to $1/5,900$ pixel. Saturated images are present, evidencing that the astrometric precision is mostly preserved across the CCD columns, whereas it features a graceful degradation in the along column direction. The cumulative performance of the image set is a few micro-pixel across columns, or a few 10 micro-pixel along columns. Conclusions. The idea of astrometric precision down to a small fraction of a CCD pixel, given sufficient signal to noise ratio, is confirmed by real data from an in-flight science instrument to the $10^{-6}$ pixel level. Implications for future high precision astrometry missions are briefly discussed.

Understanding the magnetic connections from the Sun to interplanetary space is crucial for linking in situ particle observations with the solar source regions of the particles. A simple connection along the large-scale Parker spiral magnetic field is made complex by the turbulent random-walk of field lines. In this paper, we present the first analytical model of heliospheric magnetic fields where the dominant 2D component of the turbulence is transverse to the Parker spiral. The 2D wave field is supplemented with a minor wave field component that has asymptotically slab geometry at small and large heliocentric distances. We show that turbulence spreads field lines from a small source region at the Sun to a 60$^\circ$ heliolongitudinal and -latitudinal range at 1~au, with standard deviation of the angular spread of the field lines $14^\circ$. Small source regions map to an intermittent range of longitudes and latitudes at 1~au, consistent with dropouts in solar energetic particle intensities. The lengths of the field lines are significantly extended from the nominal Parker spiral length of 1.17~au up to 1.6~au, with field lines from sources at and behind the west limb considerably longer than those closer to the solar disk centre. We discuss the implications of our findings on understanding charged particle propagation, and the importance of understanding the turbulence properties close to the Sun.

Spiral galaxies undergo strong ram-pressure effects when they fall into the galaxy cluster potential. As a consequence, their gas is stripped to form extended tails within which star formation can happen, giving them the typical jellyfish appearance. The ultraviolet imaging observations of jellyfish galaxies provide an opportunity to understand ongoing star formation in the stripped tails. We report the ultraviolet observations of the jellyfish galaxies JW39, JO60, JO194 and compare with observations in optical continuum and $\mathrm{H}{\alpha}$. We detect knots of star formation in the disk and tails of the galaxies and find that their UV and H$\alpha$ flux are well correlated. The optical emission line ratio maps of these galaxies are used to identify for every region the emission mechanism, due to either star formation, LINER or a mix of the two phenomena. The star-forming regions in the emission line maps match very well with the regions having significant UV flux. The central regions of two galaxies (JW39, JO194) show a reduction in UV flux which coincides with composite or LINER regions in the emission line maps. The galaxies studied here demonstrate significant star formation in the stripped tails, suppressed star formation in the central regions and present a possible case of accelerated quenching happening in jellyfish galaxies.

The Euclid satellite is an ESA mission scheduled for launch in September 2023. To optimally perform critical stages of the data reduction, such as object detection and morphology determination, a new and modern software package was required. We have developed SourceXtractor++ as open source software for detecting and measuring sources in astronomical images. It is a complete redesign of the original SExtractor, written mainly in C++. The package follows a modular approach and facilitates the analysis of multiple overlapping sources over many images with different pixel grids. SourceXtractor++ is already operational in many areas of the Euclid processing, and we demonstrate here the capabilities of the current version v0.19 on the basis of a set of typical use cases, which are available for download

Due to their cosmological distances high-energy astrophysical sources allow for unprecedented tests of fundamental physics. Gamma-ray bursts (GRBs) comprise among the most sensitive laboratories for exploring the violation of the central physics principle of Lorentz invariance (LIV), by exploiting spectral time lag of arriving photons. It has been believed that GRB spectral lags are inherently related with their luminosities, and intrinsic source contributions, which remain poorly understood, could significantly impact the LIV results. Using a combined sample of 49 long and short GRBs observed by the Swift telescope, we perform a stacked spectral lag search for LIV effects. We set novel limits on LIV, including limits on quadratic effects, and systematically explore for the first time the impacts of the intrinsic GRB lag-luminosity relation. We find that source contributions can strongly impact resulting LIV tests, modifying their limits by up to a factor of few. We discuss constraints coming from GRB 221009A.

In this study we examine the radial dependence of the inertial and dissipation range indices, as well as the spectral break separating the inertial and dissipation range in power density spectra of interplanetary magnetic field fluctuations using {\it Parker Solar Probe} data from the fifth solar encounter between $\sim$0.1 and $\sim$0.7 au. The derived break wavenumber compares reasonably well with previous estimates at larger radial distances and is consistent with gyro-resonant damping of Alfv\'enic fluctuations by thermal protons. We find that the inertial scale power law index varies between approximately -1.65 and -1.45. This is consistent with either the Kolmogorov (-5/3) or Iroshnikov-Kraichnan (-3/2) values, has a very weak radial dependence with a possible hint that the spectrum becomes steeper closer to the Sun. The dissipation range power law index, however, has a clear dependence on radial distance (and turbulence age), decreasing from -3 near 0.7 au (4 days) to -4 [$\pm$0.3] at 0.1 au (0.75 days) closer to the Sun.

This article reviews the two major recent developments that significantly improved cosmological measurements of fundamental constants derived from high resolution quasar spectroscopy. The first one is the deployment of astronomical Laser Frequency Combs on high resolution spectrographs and the second one is the development of spectral analysis tools based on Artificial Intelligence methods. The former all but eliminated the previously dominant source of instrumental uncertainty whereas the latter established optimal methods for measuring the fine structure constant ($\alpha$) in quasar absorption systems. The methods can be used on data collected by the new ESPRESSO spectrograph and the future ANDES spectrograph on the Extremely Large Telescope to produce unbiased $\Delta\alpha/\alpha$ measurements with unprecedented precision.

A giant impact is commonly thought to explain the dramatic contrast in elevation and crustal thickness between the two hemispheres of Mars known as the "Martian Dichotomy". Initially, this scenario referred to an impact in the northern hemisphere that would lead to a huge impact basin (dubbed the "Borealis Basin"), while more recent work has instead suggested a hybrid origin that produces the Dichotomy through impact-induced crust-production. The majority of these studies have relied upon impact scaling-laws inaccurate at such large-scales, however, and those that have included realistic impact models have utilised over-simplified geophysical models and neglected any material strength. Here we use a large suite of strength-including smoothed-particle hydrodynamics (SPH) impact simulations coupled with a more sophisticated geophysical scheme of crust production and primordial crust to simultaneously investigate the feasibility of a giant impact on either hemisphere of Mars to have produced its dichotomous crust distribution, and utilise spherical harmonic analysis to identify the best-fitting cases. We find that the canonical Borealis-forming impact is not possible without both excessive crust production and strong antipodal effects not seen on Mars' southern hemisphere today. Our results instead favour an impact and subsequent localised magma ocean in the southern hemisphere that results in a thicker crust than the north upon crystallisation. Specifically, our best-fitting cases suggest that the projectile responsible for the Dichotomy-forming event was of radius 500-750 km, and collided with Mars at an impact angle of 15-30{\deg} with a velocity of 1.2-1.4 times mutual escape speed ($\sim$6-7 km/s).

We present a new constraint on the mass of the black hole in the active S0 galaxy NGC 5273. Due to the proximity of the galaxy at $16.6 \pm 2.1$ Mpc, we were able to resolve and extract the bulk motions of stars near the central black hole using AO-assisted observations with Gemini NIFS, as well as constrain the large-scale kinematics using re-reduced archival SAURON spectroscopy. High resolution HST imaging allowed us to generate a surface brightness decomposition, determine approximate mass-to-light ratios for the bulge and disk, and obtain an estimate for the disk inclination. We constructed an extensive library of dynamical models using the Schwarzschild orbit-superposition code FORSTAND, exploring a range of disk and bulge shapes, halo masses, etc. We determined a black hole mass of $M_{\bullet} = [0.5 - 2] \times 10^{7}$ $M_{\odot}$, where the low side of the range is in agreement with the reverberation mapping measurement of $M_{\bullet} = [4.7 \pm 1.6] \times 10^{6}$ $M_{\odot}$. NGC 5273 is one of only a small number of nearby galaxies hosting broad-lined AGN, allowing crucial comparison of the black hole masses derived from different mass measurement techniques.

A tight positive correlation between the stellar mass and the gas-phase metallicity of galaxies has been observed at low redshifts, with only $\sim 0.1$ dex scatter in metallicity. The shape and normalization of this correlation can set strong constraints on theories of galaxy evolution. In particular, its redshift evolution is thought to be determined by stellar and active galactic nucleus feedback-driven outflows, the redshift evolution of the stellar initial mass function or stellar yields, and broadly the star-formation histories of galaxies. The advent of \jwst\ allows probing the mass--metallicity relation at redshifts far beyond what was previously accessible. Here we report the discovery of two emission-line galaxies at redshift $z = 8.15$ and $z = 8.16$ in \jwst\ NIRCam imaging and NIRSpec spectroscopy of galaxies gravitationally lensed by the cluster RX\,J2129.4$+$0009. We measure their metallicities using the strong-line method and their stellar masses through spectral-energy-distribution fitting with a nonparametric star-formation history. We combine these with nine similarly re-analysed galaxies at $7.2 < z < 9.5$ to compile a sample of eleven galaxies at $z \approx 8$ (six with \jwst\ metallicities and five with ALMA metallicities). Based on this sample, we report the first quantitative statistical inference of the mass--metallicity relation at $z\approx8$ (median $z = 8.15$). We measure a $\sim 1.0$ dex redshift evolution in the normalization of the mass--metallicity relation from $z \approx 8$ to the local Universe; at fixed stellar mass, galaxies are 10 times less metal enriched at $z \approx 8$ compared to the present day (abridged).

While there have been far fewer missions to the outer Solar System than to the inner Solar System, spacecraft destined for the giant planets have conducted a wide range of fundamental investigations, returning data that continues to reshape our understanding of these complex systems, sometimes decades after the data were acquired. These data are preserved and accessible from national and international planetary science archives. For all NASA planetary missions and instruments the data are available from the science discipline nodes of the NASA Planetary Data System (PDS). Looking ahead, the PDS will be the primary repository for giant planets data from several upcoming missions and derived datasets, as well as supporting research conducted to aid in the interpretation of the remotely sensed giant planets data already archived in the PDS.

I report updates to the substellar mass-radius diagram for 11 transiting brown dwarfs (BDs) and low-mass stars published before the third data release from the Gaia mission (Gaia DR3). I reanalyse these transiting BD systems whose physical parameters were published between 2008 and 2019 and find that when using the parallax measurements from Gaia DR3, 7 BDs show significant differences in their radius estimate or an improvement in the radius uncertainty. This has important implications for how these BDs are used to test substellar evolutionary models in the mass-radius diagram. The remaining 4 BDs show mass-radius estimates that are consistent with their previous pre-Gaia DR3 measurements. The 7 BDs that show significant deviation from the original mass-radius measurements are AD 3116b, CoRoT-3b, CoRoT-15b, EPIC 201702477b, Kepler-39b, KOI-205b, and KOI-415b. Of these, AD 3116b is a known member of the Praesepe cluster at an age of 600 Myr. Additionally, some of the previously smallest known transiting BDs, KOI-205b and KOI-415b, are not as small as once thought, leaving the mass-radius region for the very oldest BDs relatively sparse as a result of this work.

Lambert's problem has been long studied in the context of space operations; its solution enables accurate orbit determination and spacecraft guidance. This work offers an analytical solution to Lambert's problem using the Koopman Operator (KO). In contrast to previous methods in the literature, the KO provides the analysis of a nonlinear system by seeking a transformation that embeds the nonlinear dynamics into a global linear representation. Our new methodology to solve for Lambert solutions considers the position of the system's eigenvalues on the phase plane, evaluating accurate state transition polynomial maps for a computationally efficient propagation of the dynamics. The methodology used and multiple-revolution solutions found are compared in accuracy and performance with other techniques found in the literature, highlighting the benefits of the newly developed analytical approach over classical numerical methodologies.

Discrete ordinate ($S_N$) and filtered spherical harmonics ($FP_N$) based schemes have been proven to be robust and accurate in solving the Boltzmann transport equation but they have their own strengths and weaknesses in different physical scenarios. We present a new method based on a finite element approach in angle that combines the strengths of both methods and mitigates their disadvantages. The angular variables are specified on a spherical geodesic grid with functions on the sphere being represented using a finite element basis. A positivity-preserving limiting strategy is employed to prevent non-physical values from appearing in the solutions. The resulting method is then compared with both $S_N$ and $FP_N$ schemes using four test problems and is found to perform well when one of the other methods fail.

We present a method for improving the performance of nested sampling as well as its accuracy. Building on previous work by Chen et al., we show that posterior repartitioning may be used to reduce the amount of time nested sampling spends in compressing from prior to posterior if a suitable ``proposal'' distribution is supplied. We showcase this on a cosmological example with a Gaussian posterior, and release the code as an LGPL licensed, extensible Python package https://gitlab.com/a-p-petrosyan/sspr.

The kinetics and energetic relaxation associated with collisions between fast and thermal atoms are of fundamental interest for escape and therefore also for the evolution of the Mars atmosphere. The total and differential cross-sections of fast O($^3P$) atom collisions with CO have been calculated from quantum mechanical calculations. The cross-sections are computed at collision energies from 0.4 to 5 eV in the center-of-mass frame relevant to the planetary science and astrophysics. All the three potential energy surfaces ($^3$A', $^3$A" and 2 $^3$A" symmetry) of O($^3P$) + CO collisions separating to the atomic ground state have been included in calculations of cross-sections. The cross-sections are computed for all three isotopes of energetic O($^3P$) atoms collisions with CO. The isotope dependence of the cross-sections are compared. Our newly calculated data on the energy relaxation of O atoms and their isotopes with CO molecules will be very useful to improve the modeling of escape and energy transfer processes in the Mars' upper atmosphere.

The short-duration noise transients in LIGO and Virgo detectors significantly affect the search sensitivity of compact binary coalescence (CBC) signals, especially in the high mass region. In the previous work by the authors \cite{Joshi_2021}, a $\chi^2$ statistic was proposed to distinguish them from CBCs. This work is an extension where we demonstrate the improved noise-discrimination of the optimal $\chi^2$ statistic in real LIGO data. The tuning of the optimal $\chi^2$ includes accounting for the phase of the CBC signal and a well informed choice of sine-Gaussian basis vectors to discern how CBC signals and some of the most worrisome noise-transients project differently on them~\cite{sunil_2022}. We take real blip glitches (a type of short-duration noise disturbance) from the second observational (O2) run of LIGO-Hanford and LIGO-Livingston detectors. The binary black hole signals were simulated using \textsc{IMRPhenomPv2} waveform and injected into real LIGO data from the same run. We show that in comparison to the traditional $\chi^2$, the optimal $\chi^2$ improves the signal detection rate by around 4\% in a lower-mass bin ($m_1,m_2 \in [20,40]M_{\odot}$) and by more than 5\% in a higher-mass bin ($m_1,m_2 \in [60,80]M_{\odot}$), at a false alarm probability of $10^{-3}$. We find that the optimal $\chi^2$ also achieves significant improvement over the sine-Gaussian $\chi^2$.

In this paper, we first analyze the horizon structure of the Van der Waals(VdW) black hole and then investigate its shadow in the absence of a plasma medium as well as the presence of a homogeneous plasma medium. We find that both the Van der Waals parameters $a$ and $b$ have a significant effect on the shadow of the black hole. We also observe that the radius of the shadow in a homogeneous plasma medium decreases while parameter $\sigma =\frac{\omega_p}{\omega_{\infty}}$ ( the ratio of plasma frequency and photon frequency) increases and the radius of the shadow inhomogeneous plasma medium is larger than the vacuum medium. We also discuss the strong gravitational lensing in a homogeneous plasma medium. We observe that the photon sphere radius, deflection limit coefficients and deflection angle in the strong field are highly affected by the presence of a homogeneous plasma medium. We also find that the deflection angle in the strong field limit by the Van der Waals black hole with the homogeneous plasma is greater than that of the Vacuum medium. Further, we discuss the observables quantities angular position $\theta_{\infty}$, separation $S$ and magnification $r_{mag}$ by taking the example of a supermassive black hole in the strong field limit with the effects of homogeneous plasma. It is concluded that the Van der Waals parameters $a$, $b$ and homogeneous plasma medium have a significant effect on both the shadows and strong gravitational lensing.

Nuclear astrophysics is a multi-disciplinary field with a huge demand for nuclear data. Among its various fields, stellar evolution and nucleosynthesis are clearly the most closely related to nuclear physics. The need for nuclear data for astrophysics applications challenges experimental techniques as well as the robustness and predictive power of present nuclear models. Despite impressive progress for the last years, major problems and puzzles remain. In the present contribution, only a few nuclear astrophysics specific aspects are discussed. These concern some experimental progress related to the measurement of key reactions of relevance for the so-called s-and p-processes of nucleosynthesis, the theoretical effort in predicting nuclear properties of exotic neutron-rich nuclei of interest for the r-process nucleosynthesis, and the recent introduction of machine learning techniques in nuclear astrophysics applications.

The imprint of extremely low frequency primordial gravitational wave on a gravitational lens system with a non-aligned source-deflector-observer configuration is investigated in work (Liu, 2022, MNRAS, 517, 2769) from which it shows that time delay with perturbation from extremely low frequency primordial gravitational wave could deviate from the one deduced from the theoretical model as much as 100 percent with a series of chosen parameters. However, the frequency of gravitational wave chosen in work (Liu, 2022, MNRAS, 517, 2769) is a little bit confusing. Here, with the suitable parameters chosen in this work, the results show that time delay between different images of the source in the gravitational lens system with perturbation from primordial gravitational wave with extremely low frequency could strongly deviate from the one resulting from the theoretical model as much as about several hundred percent, indicating that time delay from gravitational lens system could be used to detect extremely low frequency primordial gravitational wave.

The properties of neutron stars are studied in a composite model of the strong interaction. In the regime of low to medium baryonic densities a covariant hadronic model is adopted which includes an effective hyperon-hyperon vertex. The presence of free quarks in the core of the star is considered by using the Nambu-Jona Lasinio model supplemented with a vector interaction. The deconfinement process is described by a continuous coexistence of phases. Several structure parameters of neutron stars, such as mass-radius relation, moment of inertia, tidal deformability, and the propagation of nonradial f and g-modes within the relativistic Cowling approximation are studied. The predictions of the model are in good agreement with recent observational data.

Using an eigenfunction expansion to solve the transport equation, complemented by Monte-Carlo simulations, we show that ultrarelativistic shocks can be effective particle accelerators even when they fail to produce large amplitude turbulence in the downstream plasma. This finding contradicts the widely held belief that a uniform downstream magnetic field perpendicular to the shock normal inhibits acceleration by the first order Fermi process. In the ultrarelativistic limit, we find a stationary power-law particle spectrum of index s=4.17 for these shocks, close to that predicted for a strictly parallel shock.

We discuss slowly-rotating, general relativistic, superfluid neutron stars in the Hartle-Thorne formulation. The composition of the stars is described by a simple two-fluid model which accounts for superfluid neutrons and all other constituents. We apply a perturbed matching framework to derive a new formalism for slowly-rotating superfluid neutron stars, valid up to second-order perturbation theory, building on the original formulation reported by Andersson and Comer in 2001. The present study constitutes an extension of previous work in the single-fluid case where it was shown that the Hartle-Thorne formalism needs to be amended since it does not provide the correct results when the energy density does not vanish at the surface of the star. We discuss in detail the corrections that need to be applied to the original two-fluid formalism in order to account for non vanishing energy densities at the boundary. In the process, we also find a correction needed in the computation of the deformation of the stellar surface in the original two-fluid model in all cases (irrespective of the value of the energy density at the surface). The discrepancies found between the two formalisms are illustrated by building numerical stellar models, focusing on the comparison in the calculation of the stellar mass, the deformation of the star, and in the Kepler limit of rotation. In particular, using a toy-model equation of state for which the energy density does not vanish at the boundary of the star we demonstrate that the corrections to the formalism we find impact the structure of slowly-rotating superfluid neutron stars in a significant way.

It is well known that helical magnetohydrodynamic (MHD) turbulence exhibits an inverse transfer of magnetic energy from small to large scales, which is related to the approximate conservation of magnetic helicity. Recently, several numerical investigations noticed the existence of an inverse energy transfer also in nonhelical MHD flows. We run a set of fully resolved direct numerical simulations and perform a wide parameter study of the inverse energy transfer and the decaying laws of helical and nonhelical MHD. Our numerical results show only a small inverse transfer of energy that grows as with increasing Prandtl number (Pm). This latter feature may have interesting consequences for cosmic magnetic field evolution. Additionally, we find that the decaying laws $E \sim t^{-p}$ are independent of the scale separation and depend solely on Pm and Re. In the helical case we measure a dependence of the form $p_b \approx 0.6 + 14/Re$. We also make a comparison between our results and previous literature and discuss the possible reason for the observed disagreements.

WIMPs, weakly-interacting massive particles, have been leading candidates for particle dark matter for decades, and they remain a viable and highly motivated possibility. In these lectures, I describe the basic motivations for WIMPs, beginning with the WIMP miracle and its under-appreciated cousin, the discrete WIMP miracle. I then give an overview of some of the basic features of WIMPs and how to find them. These lectures conclude with some variations on the WIMP theme that have by now become significant topics in their own right and illustrate the richness of the WIMP paradigm.

Atomic dark matter (aDM) is a simple but highly theoretically motivated possibility for an interacting dark sector that could constitute some or all of dark matter. We perform a comprehensive study of precision cosmological observables on minimal atomic dark matter, exploring for the first time the full parameter space of dark QED coupling and dark electron and proton masses $(\alpha_{D}, m_{e_{D}}, m_{p_{D}})$ as well as the two cosmological parameters of aDM mass fraction $f_D$ and temperature ratio $\xi$ at time of SM recombination. We find that significant aDM mass fractions require the dark electron mass to obey an $\alpha_{D}$-dependent lower bound. We also show how aDM can accommodate the $(H_0, S_8)$ tension from late-time measurements, leading to a significantly better fit than $\Lambda$CDM or $\Lambda$CDM + dark radiation. Furthermore, including late-time measurements leads to strikingly tight constraints on the parameters of atomic dark matter. The dark QED coupling must obey an upper bound of $\alpha_{D} < 0.025$, the dark electron cannot be lighter than the SM electron, and $\Delta N_D, f_{D} \gtrsim 0.1$ are preferred. The dark proton mass is seemingly unconstrained. Our results serve as an important new jumping-off point for future precision studies of atomic dark matter at non-linear and smaller scales.