Papers for Monday, Jul 11 2022

The point-spread function (PSF) of an imaging system describes the response of the system to a point source. Accurately determining the PSF enables one to correct for the combined effects of focussing and scattering within the imaging system, and thereby enhance the spatial resolution and dynamic contrast of the resulting images. We present a semi-empirical semi-blind methodology to derive a PSF from partially occulted images. We partition the two-dimensional PSF into multiple segments, set up a multi-linear system of equations, and directly fit the system of equations to determine the PSF weight in each segment. The algorithm is guaranteed to converge towards the correct instrumental PSF for a large class of occultations, does not require a predefined functional form of the PSF, and can be applied to a large variety of partially occulted images, such as within laboratory settings, regular calibrations within a production line or in the field, astronomical images of distant clusters of stars, or partial solar eclipse images. We show that the central weight of the PSF, which gives the percentage of photons that are not scattered by the instrument, is accurate to bettern than 0.3%. The mean absolute percentage error between the reconstructed and true PSF is usually between 0.5% and 5% for the entire PSF, between 0.5% and 5% for the PSF core, and between 0.5% and 3% for the PSF tail.

We have mapped the number density and mean vertical velocity of the Milky Way's stellar disk out to a distance of a few kiloparsecs using Gaia Data Release 3 (DR3) and complementary photo-astrometric distance information from StarHorse. For the number counts, we carefully masked spatial regions that are compromised by open clusters, great distances, or dust extinction and used Gaussian processes to arrive at a smooth, non-parametric estimate for the underlying number density field. We find that the number density and velocity fields depart significantly from an axisymmetric and mirror-symmetric model. These departures, which include projections of the Gaia phase-space spiral, signal the presence of local disturbances in the disk. We identify two distinct features in both stellar number density and mean vertical fields and associate them with the Local Spiral Arm and the Galactic warp. The Local Spiral Arm feature is present mainly in the thin disk and is largely symmetric across the disk mid-plane in both density and velocity. The density and velocity fields are phase-shifted by roughly a quarter wavelength in the direction perpendicular to their axis of elongation, suggesting a breathing mode that is propagating in the direction of Galactic longitude $l\sim 270$ deg. The Galactic warp feature is asymmetric about the mid-plane and can be explained by a tilt of the thick stellar disk in the direction of the Galactic anti-centre, while the thin stellar disk remains flat.

Accurately reproducing the thin cold gas discs observed in nearby spiral galaxies has been a long standing issue in cosmological simulations. Here, we present measurements of the radially resolved HI scale height in 22 non-interacting Milky Way-mass galaxies from the FIREbox cosmological volume. We measure the HI scale heights using five different approaches commonly used in the literature: fitting the vertical volume density distribution with a Gaussian, the distance between maximum and half-maximum of the vertical volume density distribution, a semi-empirical description using the velocity dispersion and the galactic gravitational potential, the analytic assumption of hydrostatic equilibrium, and the distance from the midplane which encloses $\gtrsim$60 per cent of the HI mass. We find median HI scale heights, measured using the vertical volume distribution, that range from ~100 pc in the galactic centres to ~800 pc in the outskirts and are in excellent agreement with recent observational results. We speculate that the presence of a realistic multiphase interstellar medium, including cold gas, and realistic stellar feedback are the drivers behind the realistic HI scale heights.

We present deep broadband radio polarization observations of the Spiderweb radio galaxy (J1140-2629) in a galaxy proto-cluster at $z=2.16$. These yield the most detailed polarimetric maps yet made of a high redshift radio galaxy. The intrinsic polarization angles and Faraday Rotation Measures (RMs) reveal coherent magnetic fields spanning the $\sim60$ kpc length of the jets, while $\sim50$% fractional polarizations indicate these fields are well-ordered. Source-frame absolute RM values of $\sim1,000$ rad/m/m are typical, and values up to $\sim11,100$ rad/m/m are observed. The Faraday-rotating gas cannot be well-mixed with the synchrotron-emitting gas, or stronger-than-observed depolarization would occur. Nevertheless, an observed spatial coincidence between a localized absolute RM enhancement of $\sim1,100$ rad/m/m, a bright knot of Ly$\alpha$ emission, and a deviation of the radio jet provide direct evidence for vigorous jet-gas interaction. We detect a large-scale RM gradient totaling $\sim1,000$s rad/m/m across the width of the jet, suggesting a net clockwise (as viewed from the AGN) toroidal magnetic field component exists at 10s-of-kpc-scales, which we speculate may be associated with the operation of a Poynting-Robertson cosmic battery. We conclude the RMs are mainly generated in a sheath of hot gas around the radio jet, rather than the ambient foreground proto-cluster gas. The estimated magnetic field strength decreases by successive orders-of-magnitude going from the jet hotspots ($\sim90$ $\mu$G) to the jet sheath ($\sim10$ $\mu$G) to the ambient intracluster medium ($\sim1$ $\mu$G). Synthesizing our results, we propose that the Spiderweb radio galaxy is actively magnetizing its surrounding proto-cluster environment, with possible implications for theories of the origin and evolution of cosmic magnetic fields.

The ultra-faint dwarf galaxy Reticulum~II was enriched by a single rare and prolific r-process event. The r-process content of Reticulum~II thus provides a unique opportunity to study metal mixing in a relic first galaxy. Using multi-object high-resolution spectroscopy with VLT/GIRAFFE and Magellan/M2FS, we identify 32 clear spectroscopic member stars and measure abundances of Mg, Ca, Fe, and Ba where possible. We find $72^{+10}_{-12}$% of the stars are r-process-enhanced, with a mean $\left\langle\mbox{[Ba/H]}\right\rangle=-1.68~\pm~0.07$ and unresolved intrinsic dispersion $\sigma_{\rm [Ba/H]} < 0.20$. The homogeneous r-process abundances imply that Ret~II's metals are well-mixed by the time the r-enhanced stars form, which simulations have shown requires at least 100 Myr of metal mixing in between bursts of star formation to homogenize. This is the first direct evidence of bursty star formation in an ultra-faint dwarf galaxy. The homogeneous dilution prefers a prompt and high-yield r-process site, such as collapsar disk winds or prompt neutron star mergers. We also find evidence from [Ba/H] and [Mg/Ca] that the r-enhanced stars in Ret~II formed in the absence of substantial pristine gas accretion, perhaps indicating that ${\approx}70$% of Ret~II stars formed after reionization.

Models of dark sectors with a mass threshold can have important cosmological signatures. If, in the era prior to recombination, a relativistic species becomes non-relativistic and is then depopulated in equilibrium, there can be measurable impacts on the CMB as the entropy is transferred to lighter relativistic particles. In particular, if this ``step'' occurs near $z\sim 20,000$, the model can naturally accommodate larger values of $H_0$. If this stepped radiation is additionally coupled to dark matter, there can be a meaningful impact on the matter power spectrum as dark matter can be coupled via a species that becomes non-relativistic and depleted. This can naturally lead to suppressed power at scales inside the sound horizon before the step, while leaving conventional CDM signatures for power outside the sound horizon. We study these effects and show such models can naturally provide lower values of $S_8$ than scenarios without a step. This suggests these models may provide an interesting framework to address the $S_8$ tension, both in concert with the $H_0$ tension and without.

The last generation of X-ray focusing telescopes operating outside the Earth's radiation belt discovered that optics were able to focus not only astrophysical X-ray photons, but also low-energy heliophysical protons entering the Field of View (FOV). This "soft proton" contamination affects around 40\% of the observation time of XMM-Newton. The ATHENA Charged Particle Diverter (CPD) was designed to use magnetic fields to move these soft protons away from the FOV of the detectors, separating the background-contributing ions in the focused beam from the photons of interest. These magnetically deflected protons can hit other parts of the payload and scatter back to the focal plane instruments. Evaluating the impact of this secondary scattering with accurate simulations is essential for the CPD scientific assessment. However, while Geant4 simulations of grazing soft proton scattering on X-ray mirrors have been recently validated, the scattering on the unpolished surfaces of the payload (e.g. the baffle or the diverter itself) is still to be verified with experimental results. Moreover, the roughness structure can affect the energy and angle of the scattered protons, with a scattering efficiency depending on the specific target volume. Using Atomic Force Microscopy to take nanometer-scale surface roughness measurements from different materials and coating samples, we use Geant4 together with the CADMesh library to shoot protons at these very detailed surface roughness models to understand the effects of different material surface roughnesses, coatings, and compositions on proton energy deposition and scattering angles. We compare and validate the simulation results with laboratory experiments, and propose a framework for future proton scattering experiments.

The number of millisecond pulsars (MSPs) observed in Milky Way globular clusters has increased explosively in recent years, but the underlying population is still uncertain due to observational biases. We use state-of-the-art $N$-body simulations to study the evolution of MSP populations in dense star clusters. These cluster models span a wide range in initial conditions, including different initial masses, metallicities, and virial radii, which nearly cover the full range of properties exhibited by the population of globular clusters in the Milky Way. We demonstrate how different initial cluster properties affect the number of MSPs, for which we provide scaling relations as a function of cluster age and mass. As an application, we use our formulae to estimate the number of MSPs delivered to the Galactic Center from inspiralling globular clusters to probe the origin of the Galactic-Center gamma-ray excess detected by \textit{Fermi}. We predict about $400$ MSPs in the Galactic Center from disrupted globular clusters, which can potentially explain most of the observed gamma-ray excess.

The radial acceleration relation (RAR) represents a tight empirical relation between the inferred total and baryonic centripetal accelerations, $g_{\rm{tot}}=GM_{\rm{tot}}(<r)/r^2$ and $g_{\rm{bar}}=GM_{\rm{bar}}(<r)/r^2$, observed in galaxies and galaxy clusters. The tight correlation between these two quantities can provide insight into the nature of dark matter. Here we use BAHAMAS, a state-of-the-art suite of cosmological hydrodynamical simulations, to characterize the RAR in cluster-scale halos for both cold and collisionless dark matter (CDM) and self-interacting dark matter (SIDM) models. SIDM halos generally have reduced central dark matter densities, which reduces the total acceleration in the central region when compared with CDM. We compare the RARs in galaxy clusters simulated with different dark matter models to the RAR inferred from CLASH observations. Our comparison shows that the cluster-scale RAR in the CDM model provides an excellent match to the CLASH RAR obtained by Tian et al. including the high-acceleration regime probed by the brightest cluster galaxies (BCGs). By contrast, models with a larger SIDM cross-section yield increasingly poorer matches to the CLASH RAR. Excluding the BCG regions results in a weaker but still competitive constraint on the SIDM cross-section. Using the RAR data outside the central $r<100$kpc region, an SIDM model with $\sigma/m=0.3$cm$^{2}$g$^{-1}$ is disfavored at the $3.8\sigma$ level with respect to the CDM model. This study demonstrates the power of the cluster-scale RAR for testing the collisionless nature of dark matter.

Cosmic strings are predicted by many Standard Model extensions involving the cosmological breaking of a symmetry with nontrivial first homotopy group and represent a potential source of primordial gravitational waves (GWs). Present efforts to model the GW signal from cosmic strings are often based on minimal models, such as, e.g., the Nambu-Goto action that describes cosmic strings as exactly one-dimensional objects without any internal structure. In order to arrive at more realistic predictions, it is therefore necessary to consider nonminimal models that make an attempt at accounting for the microscopic properties of cosmic strings. With this goal in mind, we derive in this paper the GW spectrum emitted by current-carrying cosmic strings (CCCSs), which may form in a variety of cosmological scenarios. Our analysis is based on a generalized version of the velocity-dependent one-scale (VOS) model, which, in addition to the mean velocity and correlation length of the string network, also describes the evolution of a chiral (light-like) current. As we are able to show, the solutions of the VOS equations imply a temporarily growing fractional cosmic-string energy density, $\Omega_{\rm cs}$. This results in an enhanced GW signal across a broad frequency interval, whose boundaries are determined by the times of generation and decay of cosmic-string currents. Our findings have important implications for GW experiments in the Hz to MHz band and motivate the construction of realistic particle physics models that give rise to large currents on cosmic strings.

Hydrodynamic studies of stellar-mass compact objects (COs) in a common envelope (CE)have shown that the accretion rate onto the CO is a few orders of magnitude below the Bondi-Hoyle-Lyttleton (BHL) estimate. This is several orders of magnitude above the Eddington limit and above the limit for neutrino-cooled accretion (i.e., hypercritical accretion, or HCA). Considering that a binary system inside the CE of a third star accretes material at nearly the same rate as a single object of the same total mass, we propose stellar-evolution channels which form binary black hole (BBH) systems with its component masses within the pair-instability supernova (PISN) mass gap. Our model is based on HCA onto the BBH system engulfed into the CE of a massive tertiary star. Furthermore, we propose a mass transfer mode which allows to store mass lost by the binary onto a third star. Through the use of population synthesis simulations for the evolution of BBHs and standard binary-evolution principles for the interaction with a tertiary star, we are able to produce BBHs masses consistent with those estimated for GW190521. We also discuss the massive binary system Mk34 as a possible progenitor of BBHs in the PISN gap, as well as the spin distribution of the observed mergers in the gravitational-wave catalog.

We simultaneously model the gravitational potential and phase space distribution function (DF) of giant stars near the Sun using the {\it Gaia} DR2 radial velocity catalog. We assume that the Galaxy is in equilibrium and is symmetric about both the spin axis of the disk and the Galactic midplane. The potential is taken as a sum of terms that nominally represent contributions from the gas disk, stellar disk, bulge, and dark matter halo. Our DF model for the giants comprise two components to account for a mix of thin and thick disk stars. The DF for each component is described by an analytic function of the energy, the spin angular momentum, and the vertical energy, in accord with Jeans theorem. We present model predictions for the radial and vertical forces within $\sim 2\,{\rm kpc}$ of the Sun, highlighting the rotation curve and vertical force profile in the Solar Neighbourhood. Finally, we show residuals for star counts in the $R-z$ and $z-v_z$ planes as well as maps of the mean radial and azimuthal velocities in the $z-v_z$ plane. Using our model for the potential, we also examine the star count residuals in action-frequency-angle coordinates. The {\it Gaia} phase spirals, velocity arches, some of the known moving groups and bending modes appear as well-defined features in these maps.

The propagation of small bodies in the Solar system is driven by the combination of planetary encounters that cause abrupt changes in their orbits and secular long-term perturbations. We propose a propagation strategy that combines both of these effects into a single framework for long-term, rapid propagation of small bodies in the inner Solar System. The analytical secular perturbation of Jupiter is interrupted to numerically solve planetary encounters, which last a small fraction of the simulation time. The proposed propagation method is compared to numerical integrations in the Solar system, effectively capturing properties of the numerical solutions in a fraction of the computational time. We study the orbital history of the Janus mission targets: (35107) 1991 VH and (175706) 1996 FG3, obtaining a stochastic representation of their long-term dynamics and frequencies of very close encounters. Over the last million years the probability of a strongly perturbing flyby is found to be small.

Detailed observations of star forming galaxies at high redshift are critical to understand the formation and evolution of the earliest galaxies. Gravitational lensing provides an important boost, allowing observations at physical scales unreachable in unlensed galaxies. We present three lensed galaxies from the RELICS survey at $z_{phot} = 6 - 10$, including the most highly magnified galaxy at $z_{phot} \sim 6$ (WHL0137-zD1, dubbed the Sunrise Arc), the brightest known lensed galaxy at $z_{phot} \sim 6$ (MACS0308-zD1), and the only spatially resolved galaxy currently known at $z_{phot} \sim 10$ (SPT0615-JD). The Sunrise Arc contains seven star-forming clumps with delensed radii as small as 3 pc, the smallest spatial scales yet observed in a $z>6$ galaxy, while SPT0615-JD contains features measuring a few tens of parsecs. MACS0308-zD1 contains a $r\sim 30$ pc clump with a star formation rate (SFR) of $\sim 3 M_{\odot} \textrm{ yr}^{-1}$, giving it a SFR surface density of $\Sigma_{SFR} \sim 10^3 M_{\odot}\textrm{ yr}^{-1}\textrm{ kpc}^{-2}$. These galaxies provide a unique window into small scale star formation during the Epoch of Reionization. They will be excellent targets for future observations with JWST, including one approved program targeting the Sunrise Arc.

W43-MM1 is a young region, very rich in terms of high-mass star formation. We aim to systematically identify the massive cores which contain a hot core and compare their molecular composition. We used ALMA high-spatial resolution (2500 au) data of W43-MM1 to identify line-rich protostellar cores and make a comparative study of their temperature and molecular composition. The identification of hot cores is based on both the spatial distribution of the complex organic molecules and the contribution of molecular lines relative to the continuum intensity. We rely on the analysis of CH3CN and CH3CCH to estimate the temperatures of the selected cores. Finally, we rescale the spectra of the different hot cores based on their CH3OCHO line intensities to directly compare the detections and line intensities of the other species. W43-MM1 turns out to be a region rich in massive hot cores with at least 1 less massive and 7 massive hot cores. The excitation temperature of CH3CN is of the same order for all of them (120-160 K). There is a factor of up to 30 difference in the intensity of the complex organic molecules (COMs) lines. However the molecular emission of the hot cores appears to be the same within a factor 2-3. This points towards both a similar chemical composition and excitation of most of the COMs over these massive cores, which span about an order of magnitude in core mass. In contrast, CH3CCH emission is found to preferentially trace more the envelope, with a temperature ranging from 50 K to 90 K. Core 1, the most massive hot core of W43-MM1, shows a richer line spectrum than the other cores. In core 2, the emission of O-bearing molecules does not peak at the dust continuum core center; the blue and red shifted emission correspond to the outflow lobes, suggesting a formation via the sublimation of the ice mantles through shocks or UV irradiation on the walls of the cavity.

Ground-based optical astronomy necessarily involves sensing the light of astronomical objects along with the contributions of many natural sources ranging from the Earth's atmosphere to cosmological light. In addition, astronomers have long contended with artificial light pollution that further adds to the 'background' against which astronomical objects are seen. Understanding the brightness of the night sky is therefore fundamental to astronomy. The last comprehensive review of this subject was nearly a half-century ago, and we have learned much about both the natural and artificial night sky since. This Review considers which influences determine the total optical brightness of the night sky; the means by which that brightness is measured; and how night sky quality is assessed and monitored in the long term.

The neutrino fast flavor instability (FFI) can change neutrino flavor on time scales of nanoseconds and length scales of centimeters. It is expected to be ubiquitous in core-collapse supernovae and neutron star mergers, potentially modifying the neutrino signal we see, how matter is ejected from these explosions, and the types of heavy elements that form in the ejecta and enrich the universe. There has been a great deal of recent interest in understanding the role the FFI plays in supernovae and mergers, but the short length and time scales and the strong nonlinearity have prevented the FFI from being included consistently in these models. We review the theoretical nature of the FFI starting with the quantum kinetic equations, where the instability exists in neutron star mergers and supernovae, and how the instability behaves after saturation in simplified simulations. We review the proposed methods to test for instability in moment-based calculations where the full distribution is not available and describe the numerical methods used to simulate the instability directly. Finally, we close by outlining the trajectory toward realistic, self-consistent models that will allow a more complete understanding of the impact of the FFI in supernovae and mergers.

$\texttt{Eureka!}$ is a data reduction and analysis pipeline for exoplanet time-series observations, with a particular focus on James Webb Space Telescope (JWST) data. The goal of $\texttt{Eureka!}$ is to provide an end-to-end pipeline that starts with raw, uncalibrated FITS files and ultimately yields precise exoplanet transmission and/or emission spectra. The pipeline has a modular structure with six stages, and each stage uses a "Eureka! Control File" (ECF; these files use the .ecf file extension) to allow for easy control of the pipeline's behavior. Stage 5 also uses a "Eureka! Parameter File" (EPF; these files use the .epf file extension) to control the fitted parameters. We provide template ECFs for the MIRI, NIRCam, NIRISS, and NIRSpec instruments on JWST and the WFC3 instrument on the Hubble Space Telescope (HST). These templates give users a good starting point for their analyses, but $\texttt{Eureka!}$ is not intended to be used as a black-box tool, and users should expect to fine-tune some settings for each observation in order to achieve optimal results. At each stage, the pipeline creates intermediate figures and outputs that allow users to compare $\texttt{Eureka!}$'s performance using different parameter settings or to compare $\texttt{Eureka!}$ with an independent pipeline. The ECF used to run each stage is also copied into the output folder from each stage to enhance reproducibility. Finally, while $\texttt{Eureka!}$ has been optimized for exoplanet observations (especially the latter stages of the code), much of the core functionality could also be repurposed for JWST time-series observations in other research domains thanks to $\texttt{Eureka!}$'s modularity.

$ $Weak gravitational lensing is a powerful probe which is used to constrain the standard cosmological model and its extensions. With the enhanced statistical precision of current and upcoming surveys, high accuracy predictions for weak lensing statistics are needed to limit the impact of theoretical uncertainties on cosmological parameter constraints. For this purpose, we present a comparison of the theoretical predictions for the nonlinear matter and weak lensing power spectra, based on the widely used fitting functions ($\texttt{mead}$ and $\texttt{rev-halofit}$), emulators ($\texttt{EuclidEmulator}$, $\texttt{EuclidEmulator2}$, $\texttt{BaccoEmulator}$ and $\texttt{CosmicEmulator}$) and N-body simulations ($\texttt{Pkdgrav3}$). We consider the forecasted constraints on the $\Lambda \texttt{CDM}$ and $\texttt{wCDM}$ models from weak lensing for stage III and stage IV surveys. We study the relative bias on the constraints and their dependence on the assumed prescriptions. Assuming a $\Lambda \texttt{CDM}$ cosmology, we find that the relative agreement on the $S_8$ parameter is between $0.2-0.3\sigma$ for a stage III-like survey between the above predictors. For a stage IV-like survey the agreement becomes $1.4-3.0\sigma$. In the $\texttt{wCDM}$ scenario, we find broader $S_8$ constraints, and agreements of $0.18-0.26\sigma$ and $0.7-1.7\sigma$ for stage III and stage IV surveys, respectively. The accuracies of the above predictors therefore appear adequate for stage III surveys, while the fitting functions would need improvements for future stage IV weak lensing surveys. Furthermore, we find that, of the fitting functions, $\texttt{mead}$ provides the best agreement with the emulators. We discuss the implication of these findings for the preparation of the future weak lensing surveys.

The Nancy Grace Roman Space Telescope's (Roman) Coronagraph Instrument is a technology demonstration equipped to achieve flux contrast levels of up to 10$^{-9}$. This precision depends upon the quality of observations and their resultant on-sky corrections via an absolute flux calibration (AFC). Our plan utilizes 10 dim and 4 bright standard photometric calibrator stars from Hubble Space Telescope's (HST) CALSPEC catalog to yield a final AFC error of 1.94\% and total observation time of $\sim$22 minutes. Percent error accounts for systematic uncertainties (filters, upstream optics, quantum efficiency) in Roman component instrumentation along with shot noise for a signal to noise ratio (SNR) of 500.

The CALorimetric Electron Telescope (CALET) on the International Space Station (ISS) consists of a high-energy cosmic ray CALorimeter (CAL) and a lower-energy CALET Gamma ray Burst Monitor (CGBM). CAL is sensitive to electrons up to 20 TeV, cosmic ray nuclei from Z = 1 through Z $\sim$ 40, and gamma rays over the range 1 GeV - 10 TeV. CGBM observes gamma rays from 7 keV to 20 MeV. The combined CAL-CGBM instrument has conducted a search for gamma ray bursts (GRBs) since Oct. 2015. We report here on the results of a search for X-ray/gamma ray counterparts to gravitational wave events reported during the LIGO/Virgo observing run O3. No events have been detected that pass all acceptance criteria. We describe the components, performance, and triggering algorithms of the CGBM - the two Hard X-ray Monitors (HXM) consisting of LaBr$_{3}$(Ce) scintillators sensitive to 7 keV to 1 MeV gamma rays and a Soft Gamma ray Monitor (SGM) BGO scintillator sensitive to 40 keV to 20 MeV - and the high-energy CAL consisting of a CHarge-Detection module (CHD), IMaging Calorimeter (IMC), and fully active Total Absorption Calorimeter (TASC). The analysis procedure is described and upper limits to the time-averaged fluxes are presented.

We report the detection of an ionized gas outflow from an $X$-ray active galactic nucleus (AGN) hosted in a massive quiescent galaxy in a protocluster at $z=3.09$ (J221737.29+001823.4). It is a type-2 QSO with broad ($W_{80}>1000$ km s$^{-1}$) and strong ($\log (L_{\rm [OIII]}$ / erg s$^{-1})\approx43.4$) [O {\footnotesize III}]$\lambda\lambda$4959,5007 emission lines detected by slit spectroscopy in three-position angles using Multi-Object Infra-Red Camera and Spectrograph (MOIRCS) on the Subaru telescope and the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) on the Keck-I telescope. In the all slit directions, [O {\footnotesize III}] emission is extended to $\sim15$ physical kpc and indicates a powerful outflow spreading over the host galaxy. The inferred ionized gas mass outflow rate is $\rm 22\pm3~M_{\odot}~yr^{-1}$. Although it is a radio source, according to the line diagnostics using H$\beta$, [O {\footnotesize II}], and [O {\footnotesize III}], photoionization by the central QSO is likely the dominant ionization mechanism rather than shocks caused by radio jets. On the other hand, the spectral energy distribution of the host galaxy is well characterized as a quiescent galaxy that has shut down star formation by several hundred Myr ago. Our results suggest a scenario that QSOs are powered after the shut-down of the star formation and help to complete the quenching of massive quiescent galaxies at high redshift.

Gas accretion onto the circumplanetary disks and the source region of accreting gas are important to reveal dust accretion that leads to satellite formation around giant planets. We performed local three-dimensional high-resolution hydrodynamic simulations of isothermal and inviscid gas flow around a planet to investigate planetary-mass dependence of gas accretion band width and gas accretion rate onto circumplanetary disks. We examined cases with various planetary masses corresponding to M_p=0.05-1M_{Jup} at 5.2 au, where M_{Jup} is the current Jovian mass. We found that the radial width of the gas accretion band is proportional to M_p^{1/6} for the low-mass regime with M_p < 0.2 M_{Jup} while it is proportional to M_p for the high-mass regime with M_p > 0.2M_{Jup}. We found that the ratio of the mass accretion rate onto the circumplanetary disk to that into the Hill sphere is about 0.4 regardless of planetary mass for the cases we examined. Combining our results with the gap model obtained from global hydrodynamic simulations, we derive semi-analytical formulae of mass accretion rate onto circumplanetary disks. We found that the mass dependence of our three-dimensional accretion rates is the same as the previously-obtained two-dimensional case, although the qualitative behavior of accretion flow onto the CPD is quite different between the two cases.

We report on the near-infrared polarimetric observations of G11.11--0.12 with the 1.4 m IRSF telescope. The starlight polarization of the background stars reveals the magnetic fields in the envelope of G11.11--0.12, which are consistent in orientation with the magnetic fields obtained from submillimeter dust polarization. The magnetic fields in G11.11--0.12 are perpendicular to the filament in a large column density range, independent of the relative orientations of G11.11--0.12. The field strength on the plane of the sky in G11.11--0.12 has a typical value of $152\pm17\,\mu$G. The analyses of the magnetic fields and gas velocity dispersion indicate that the envelope of G11.11--0.12 is supersonic and sub-Alfv{\'e}nic to trans-Alfv{\'e}nic. The mass-to-flux ratio in the outer part of the envelope is $\lesssim 1$ and slightly increases to $\gtrsim 1$ closer to the filament. The weights on the relative importance of magnetic fields, turbulence and gravity indicate that gravity has been dominating the dynamical state of G11.11--0.12, with significant contribution from magnetic fields. The field strength increases slower than the gas density from the envelope to the spine of G11.11--0.12, characterized by the relation $B\propto n^{0.2}$. The observed strength and orientation of magnetic fields in G11.11--0.12 imply that supersonic gas flow is channelled by sub-Alfv{\'e}nic magnetic fields and is assembled into filaments perpendicular to the magnetic fields. The formation of low-mass stars is enhanced in the filaments with high column density, in agreement with the excess in numbers of low-mass protostars detected in one of the densest part of G11.11--0.12.

Galaxy peculiar velocities provide an integral source of cosmological information that can be harnessed to measure the growth rate of large scale structure and constrain possible extensions to General Relativity. In this work, we present a method for extracting the information contained within galaxy peculiar velocities through an ensemble of direct peculiar velocity and galaxy clustering correlation statistics, including the effects of redshift space distortions, using data from the 6-degree Field Galaxy Survey. Our method compares the auto- and cross-correlation function multipoles of these observables with respect to the local line-of-sight, with the predictions of cosmological models. We find that the uncertainty in our measurement is improved when combining these two sources of information when compared to fitting to either peculiar velocity or clustering information separately. When combining velocity and density statistics in the range $27 < s < 123 \,$h$^{-1}$Mpc we obtain a value for the local growth rate of $f\sigma_8 = 0.357 \pm 0.071$ and for the linear redshift distortion parameter $\beta = 0.297 \pm 0.061$, recovering both with approximately 20 per cent accuracy. We conclude this work by comparing our measurement with other recent local measurements of the growth rate, spanning different datasets and methodologies. We find that our results are in broad agreement with those in the literature and are fully consistent with $\Lambda$CDM cosmology. Our methods can be readily scaled to analyse upcoming large galaxy surveys and achieve accurate tests of the cosmological model.

Taking advantage of $~\sim4700$ deg$^2$ optical coverage of the Southern sky offered by the VST ATLAS survey, we construct a new catalogue of photometrically selected galaxy groups and clusters using the ORCA cluster detection algorithm. The catalogue contains $\sim 22,000$ detections with $N_{200}>10$ and $\sim9,000$ with $N_{200}>20$. We estimate the photometric redshifts of the clusters using machine learning and find the redshift distribution of the sample to extend to $z\sim0.7$, peaking at $z\sim0.25$. We calibrate the ATLAS cluster mass-richness scaling relation using masses from the MCXC, Planck, ACT DR5 and SDSS redMaPPer cluster samples. We estimate the ATLAS sample to be $>95\%$ complete and $>85\%$ pure at $z<0.35$ and in the $M_{200}>1\times10^{14}$ solar mass range. At $z<0.35$, we also find the ATLAS sample to be more complete than redMaPPer, recovering a $\sim33\%$ higher fraction of Abell clusters. This higher sample completeness places the amplitude of the $z<0.35$ ATLAS cluster mass function closer to the predictions of a $\Lambda$CDM model with parameters based on the Planck CMB analyses, compared to the cluster mass functions of ACT DR5, Planck and redMaPPer samples which have lower amplitudes in this redshift range. We shall present a detailed cosmological analysis of the ATLAS cluster mass functions in paper II. In the future, optical counterparts to X-ray detected eROSITA clusters can be identified using the ATLAS sample and the catalogue is also well suited for auxiliary spectroscopic target selection in 4MOST. The ATLAS cluster catalogue is publicly available at this http URL

The detection of small exoplanets by the radial velocity (RV) technique is limited by various, not well-known, noise sources. As a consequence, current detection techniques often fail to provide reliable estimates of the "significance levels" of detection tests in terms of false alarm rates or of p-values. We aim at designing a RV detection procedure that provides reliable p-values estimates. The method incorporates ancillary information on the noise (e.g., stellar activity indicators), and specific data- or context-driven data (e.g., instrumental measurements, simulations of stellar variability) if available. The detection part of the procedure uses a detection test applied to a standardized periodogram. Standardization allows for an autocalibration of the noise sources with partially unknown statistics (Algorithm 1). The part regarding the estimation of the p-value of the test output is based on dedicated Monte Carlo simulations allowing to handle unknown parameters (Algorithm 2). The procedure is versatile in the sense that the specific couple (test, periodogram) is chosen by the user. We demonstrate by numerical experiments on synthetic and real RV data from the Sun and aCenB that the proposed methodology allows to robustly estimate the p-values. The method also provides a way to evaluate the dependence on modeling errors of the estimated p-values attributed to a reported detection, which is a critical point for RV planet detection at low signal-to-noise ratio. The python algorithms developed in this work are available on GitHub. Accurate estimation of p-values in the case where unknown parameters are involved in the detection process is an important yet newly addressed question in the field of RV detection. Although this work presents a method to this aim, the statistical literature discussed in this paper may trigger the development of other strategies.

The search for Life in the Universe generally assumes three basic life's needs: I) building block elements (i.e., CHNOPS), II) a solvent to life's reactions (generally, liquid water) and III) a thermodynamic disequilibrium. It is assumed that similar requirements might be universal in the Cosmos. On our planet, life is able to harvest energy from a wide array of thermodynamic disequilibria, generally in the form of redox disequilibrium. The amount of different redox couples used by living systems has been estimated to be in the range of several thousands of reactions. Each of these reactions has a specific midpoint redox potential accessible thanks to specialised proteins called oxidoreductases, that constitute life's engines. These proteins have one or more metal cofactors acting as catalytic centres to exchange electrons. These metals are de facto the key component of the engines that life uses to tap into the thermodynamic disequilibria needed to fuel metabolism. The availability of these transition metals is not uniform in the Universe, and it is a function of the distribution (in time and space) of the supernovae explosions and complex galaxy dynamics. Despite this, Life's need for specific metals to access thermodynamic disequilibria has been so far completely overlooked in identifying astrobiological targets. We argue that the availability of at least some transition elements appears to be an essential feature of habitability, and should be considered a primary requisite in selecting exoplanetary targets in the search for life.

Using data from the SAMI Galaxy Survey, we investigate the correlation between the projected stellar kinematic spin vector of 1397 SAMI galaxies and the line-of-sight motion of their neighbouring galaxies. We calculate the luminosity-weighted mean velocity difference between SAMI galaxies and their neighbours in the direction perpendicular to the SAMI galaxies angular momentum axes. The luminosity-weighted mean velocity offsets between SAMI and neighbours, which indicates the signal of coherence between the rotation of the SAMI galaxies and the motion of neighbours, is 9.0 $\pm$ 5.4 km s$^{-1}$ (1.7 $\sigma$) for neighbours within 1 Mpc. In a large-scale analysis, we find that the average velocity offsets increase for neighbours out to 2 Mpc. However, the velocities are consistent with zero or negative for neighbours outside 3 Mpc. The negative signals for neighbours at distance around 10 Mpc are also significant at $\sim 2$ $\sigma$ level, which indicate that the positive signals within 2 Mpc might come from the variance of large-scale structure. We also calculate average velocities of different subsamples, including galaxies in different regions of the sky, galaxies with different stellar masses, galaxy type, $\lambda_{Re}$ and inclination. Although low-mass, high-mass, early-type and low-spin galaxies subsamples show 2 - 3 $\sigma$ signal of coherence for the neighbours within 2 Mpc, the results for different inclination subsamples and large-scale results suggest that the $\sim 2 \sigma$ signals might result from coincidental scatter or variance of large-scale structure. Overall, the modest evidence of coherence signals for neighbouring galaxies within 2 Mpc needs to be confirmed by larger samples of observations and simulation studies.

Binary systems can evolve into immensely different exotic systems such as blue straggle stars (BSSs), yellow straggler stars, cataclysmic variables, type Ia supernovae depending on their initial mass, the orbital parameters and evolution. The aim of this thesis is to understand the demographics of post-mass-transfer systems (BSSs, white dwarfs and blue lurkers) present in the open clusters and how they are formed. First, we identified the cluster members using Gaia EDR3 data in six open clusters. Two of the clusters, M67 and King2, were studied in detail using UVIT, Gaia, GALEX, 2MASS and other archival photometric data. The comprehensive panchromatic study showed that (i) there is a robust mass-transfer pathway for BSSs, and blue lurkers in M67, (ii) at least 15% of BSSs in King 2 were formed via binary mass transfer. We also created a homogeneous catalogue of open cluster BSSs using Gaia DR2 data. The analysis of 868 BSSs across 208 clusters showed that (i) BSS frequency increases with age, (ii) there is a power-law relation between cluster mass and maximum number of BSSs, (iii) the formation mechanism of BSSs is dominated by binary mass transfer (54-67%) though there exists a 10-16% chance of BSSs forming through more than 2 stellar interactions. This study demonstrates that there exists an extensive variety in the demographics of binary products, and the UV observations are vital for their detection and characterisation.

The case of SN Ia Hubble diagrams from photometrically selected samples using photometric SN host galaxy redshifts is investigated. The host redshift uncertainties and the contamination by core collapse SNe are addressed. As a test, we use the 3-year photometric SN Ia sample of the SuperNova Legacy Survey (SNLS), made of 437 objects between 0.1 and 1.05 in redshift. We combine this sample with non-SNLS objects of the JLA spectroscopic sample, made of 501 objects mostly below 0.4 in redshift. We study two options for the origin of the redshifts of the photometric sample, either provided entirely from the host photometric redshift catalogue or a mixed origin where 75% of the sample can be assigned spectroscopic redshifts. Using light curve simulations subject to the same photometric selection as data, we study the impact of photometric redshift uncertainties and contamination on flat $\Lambda CDM$ fits to Hubble diagrams from such combined samples. We find that photometric redshifts and contamination lead to biased cosmological parameters. The magnitude of the bias is similar for both redshift options. This bias can be largely accounted for if photometric redshift uncertainties and contamination are taken into account when computing the SN magnitude bias correction due to selection effects. To reduce the cosmological bias further, we explore two methods to propagate redshift uncertainties into the cosmological likelihood computation, either by refitting photometric redshifts with cosmology or by sampling the redshift resolution function. Redshift refitting fails at correcting the cosmological bias whatever the redshift option, while sampling slightly reduces it in both cases. For actual data, we find compatible results with the JLA ones for mixed photometric and spectroscopic redshifts, while the full photometric option is biased but consistent with JLA when all uncertainties are included.

We characterize the magnetic activity of M dwarfs to provide the planet community with information on the energy input from the star; in particular, in addition to the frequency of optical flares directly observed with TESS, we aim at estimating the corresponding X-ray flare frequencies, making use of the small pool of known events observed simultaneously in both wavebands. We identified 112 M dwarfs with a TESS magnitude <= 11.5 for which TESS can probe the full habitable zone for transits. These 112 stars have 1276 two-minute cadence TESS light curves from the primary mission, which we searched for rotational modulation and flares. We study the link between rotation and flares and between flare properties, for example the flare amplitude-duration relation and cumulative flare energy frequency distributions (FFDs). Assuming that each optical flare is associated with a flare in the X-ray band, and making use of published simultaneous Kepler/K2 and XMM-Newton flare studies, we estimate the X-ray energy released by our detected TESS flare events. Our calibration also involves the relation between flare energies in the TESS and K2 bands. We detected more than 2500 optical flare events on a fraction of about 32% of our targets and found reliable rotation periods only for 12 stars, which is a fraction of about 11%. For these 12 targets, we present cumulative FFDs and FFD power law fits. We construct FFDs in the X-ray band by calibrating optical flare energies to the X-rays. In the absence of directly observed X-ray FFDs for main-sequence stars, our predictions can serve for estimates of the high-energy input to the planet of a typical fast-rotating early- or mid-M dwarf.

Active Galaxies with a jet pointing towards us, so-called blazars, play an important role in the field of high-energy astrophysics. One of the most important features in the classification scheme of blazars is the peak frequency of the synchrotron emission ($\nu_{\rm peak}^S$) in the spectral energy distribution (SED). In contrast to standard blazar catalogs that usually calculate the $\nu_{\rm peak}^S$ manually, we have developed a machine-learning algorithm - BlaST - that not only simplifies the estimation, but also provides a reliable uncertainty evaluation. Furthermore, it naturally accounts for additional SED components from the host galaxy and the disk emission, which may be a major source of confusion. Using our tool, we re-estimate the synchrotron peaks in the Fermi 4LAC-DR2 catalog. We find that BlaST, improves the $\nu_{\rm peak}^S$ estimation especially in those cases where the contribution of components not related to the jet is important.

A comparison of the recent LOFAR 144 MHz map of the radio source 3C 223.1 (J094124.028+394441.95) with its VLA maps at 4.9 GHz and 8.3 GHz, made by us using the archival data, establishes this X-shaped radio galaxy (XRG) as the singularly robust case where the 'wings' exhibit a distinctly flatter radio spectrum than the primary lobes. The details of its anomalous spectral gradient are unravelled here with unprecedented precision. We also highlight the 'double boomerang' type radio morphology of this XRG. It is suggested that the peculiar spectral gradient in this XRG owes to particle acceleration associated with the rebounding of the collimated backflows of synchrotron plasma streaming in its two primary lobes, as they impinge upon and encounter the magnetic tension in the prominent dusty disk of the elliptical galaxy hosting this XRG. We also draw attention to an intriguing new morphological peculiarity of XRGs, namely a lateral offset observed between the (parallel) axes of the two primary radio lobes.

We present moderate-resolution ($R\sim4000$) $K$ band spectra of the planetary-mass companion VHS 1256 b. The data were taken with the OSIRIS integral field spectrograph at the W.M. Keck Observatory. The spectra reveal resolved molecular lines from H$_{2}$O and CO. The spectra are compared to custom $PHOENIX$ atmosphere model grids appropriate for young, substellar objects. We fit the data using a Markov Chain Monte Carlo forward modeling method. Using a combination of our moderate-resolution spectrum and low-resolution, broadband data from the literature, we derive an effective temperature of 1240 K, with a range of 1200--1300 K, a surface gravity of $\log{g}=$ 3.25, with a range of 3.25--3.75 and a cloud parameter of $\log P_{cloud}=$ 6, with a range of 6.0--6.6. These values are consistent with previous studies, regardless of the new, larger system distance from GAIA EDR3 (22.2$^{+1.1}_{-1.2}$ pc). We derive a C/O ratio of 0.590$_{-0.354}^{+0.280}$ for VHS 1256b. Both our OSIRIS data and spectra from the literature are best modeled when using a larger 3 $\mu$m grain size for the clouds than used for hotter objects, consistent with other sources in the L/T transition region. VHS 1256 b offers an opportunity to look for systematics in the modeling process that may lead to the incorrect derivation of properties like C/O ratio in the high contrast regime.

The interstellar medium (ISM) is an inseparable part of the Milky Way ecosystem whose evolutionary history remains a challenging question. We trace the evolution of the molecular ISM using a sample of Young Stellar Objects (YSO) association --molecular cloud complex (YSO-MC complex). We derive their three-dimensional (3D) velocities by combining the Gaia astrometric measurements of the YSO associations and the CO observations of the associated molecular clouds. Based on the 3D velocities, we simulate the motions of the YSO-MC complexes in the Galactic potential and forecast the ISM evolution by tracing the motions of the individual complexes, and reveal the roles of shear and stellar feedback in determining ISM evolution: Galactic shear stretches Galactic-scale molecular cloud complexes, such as the G120 Complex, into Galactic-scale filaments, and it also contributes to the destruction of the filaments; while stellar feedback creates interconnected superbubbles whose expansion injects peculiar velocities into the ISM. The Galactic-scale molecular gas clumps are often precursors of the filaments and the Galactic-scale filaments are transient structures under a constant stretch by shear. This evolutionary sequence sets a foundation to interpret other gas structures. Animations are available at https://gxli.github.io/ISM-6D/movie.html.

It has been suggested that the gravitational potential can have a significant role in suppressing the star formation in the nearby galaxies. To establish observational constrains on this scenario, we investigate the connection between the dynamics, through the circular velocity curves (CVCs) as a proxy of the inner gravitational potential, and star formation quenching in 215 non-active galaxies across Hubble sequence from the Calar Alto Legacy Integral Field Area (CALIFA) survey. Our results show that galaxies with similar CVCs tend to have a certain star-formation quenching pattern. To explore these findings in more details, we construct kpc-resolved relations of the equivalent width of the H$\alpha$ ($W_{{\rm H}\alpha}$) versus the amplitude ($V_c$) and shape ($\beta= d\ln V_c/ d\ln R$) of the circular velocity at given radius. We find that the $W_{{\rm H}\alpha}-V_c$ is a declining relationship, where the retired regions of the galaxies (the ones with $W_{{\rm H}\alpha}$ values below 3 \r{A}) tend to have higher $V_c$. Differently, $W_{{\rm H}\alpha}-\beta$ is a bi-modal relationship, characterised by two peaks: concentration of the star forming regions at a positive $\beta$ (rising CVC) and another one of the retired regions with a negative $\beta$ (declining CVC). Our results show that both the amplitude of the CVC, driven by the mass of the galaxies, and the shape of the CVC, reflecting the internal structure of the galaxies, play an important role in galaxy's quenching history.

Statistical classification of the Helios solar wind observations into several populations sorted by bulk speed has revealed an outward acceleration of the wind. The faster the wind is, the smaller is this acceleration in the 0.3 - 1 au radial range (Maksimovic et al. 2020). In this article we show that recent measurements from the Parker Solar Probe (PSP) are compatible with an extension closer to the Sun of the latter Helios classification. For instance the well established bulk speed/proton temperature (u,Tp) correlation and bulk speed/electron temperature (u,Te) anti-correlation, together with the acceleration of the slowest winds, are verified in PSP data. We also model the combined PSP and Helios data, using empirical Parker-like models for which the solar wind undergoes an "iso-poly" expansion: isothermal in the corona, then polytropic at distances larger than the sonic point radius. The polytropic indices are derived from the observed temperature and density gradients. Our modelling reveals that the electron thermal pressure has a major contribution in the acceleration process of slow and intermediate winds (in the range of 300-500 km/s at 1 au), over a broad range of distances and that the global (electron and protons) thermal energy, alone, is able to explain the acceleration profiles. Moreover, we show that the very slow solar wind requires in addition to the observed pressure gradients, another source of acceleration.

We report the discovery of five cyano derivatives of propene towards TMC-1 with the QUIJOTE line survey: $trans$ and $cis$-crotononitrile ($t$-CH$_3$CHCHCN, $c$-CH$_3$CHCHCN), methacrylonitrile (CH$_2$C(CH$_3$)CN), and $gauche$ and $cis$-allyl cyanide ($g$-CH$_2$CHCH$_2$CN and $c$-CH$_2$CHCH$_2$CN). The observed transitions allowed us to derive a common rotational temperature of 7$\pm$1 K for all them. The derived column densities are N($t$-CH$_3$CHCHCN)=(5$\pm$0.5)$\times$10$^{10}$ cm$^{-2}$, N($c$-CH$_3$CHCHCN)=(1.3$\pm$0.2)$\times$10$^{11}$ cm$^{-2}$, N(CH$_2$C(CH$_3$)CN)=(1.0$\pm$0.1)$\times$10$^{11}$ cm$^{-2}$, N($g$-CH$_2$CHCH$_2$CN)=(8.0$\pm$0.8)$\times$10$^{10}$ cm$^{-2}$, and N($c$-CH$_2$CHCH$_2$CN)=(7.0$\pm$0.7)$\times$10$^{10}$ cm$^{-2}$, respectively. The abundance of cyano-propene relative to that of propene is thus $\sim$10$^{-2}$, which is considerably lower than those of other cyano derivatives of abundant hydrocarbons. Upper limits are obtained for two ethynyl derivatives of propene ($E$ and $Z$-CH$_3$CHCHCCH).

The behaviour of molecules in space is to a large extent governed by where they freeze out or sublimate. The molecular binding energy is thus an important parameter for many astrochemical studies. This parameter is usually determined with time-consuming experiments, computationally expensive quantum chemical calculations, or the inexpensive, but inaccurate, linear addition method. In this work we propose a new method based on machine learning for predicting binding energies that is accurate, yet computationally inexpensive. A machine learning model based on Gaussian Process Regression is created and trained on a database of binding energies of molecules collected from laboratory experiments presented in the literature. The molecules in the database are categorized by their features, such as mono- or multilayer coverage, binding surface, functional groups, valence electrons, and H-bond acceptors and donors. The performance of the model is assessed with five-fold and leave-one-molecule-out cross validation. Predictions are generally accurate, with differences between predicted and literature binding energies values of less than $\pm$20\%. The validated model is used to predict the binding energies of twenty one molecules that have recently been detected in the interstellar medium, but for which binding energy values are not known. A simplified model is used to visualize where the snowlines of these molecules would be located in a protoplanetary disk. This work demonstrates that machine learning can be employed to accurately and rapidly predict binding energies of molecules. Machine learning complements current laboratory experiments and quantum chemical computational studies. The predicted binding energies will find use in the modelling of astrochemical and planet-forming environments.

Long-period transiting planets provide the opportunity to better understand the formation and evolution of planetary systems. Their atmospheric properties remain largely unaltered by tidal or radiative effects of the host star, and their orbital arrangement reflects a different, and less extreme, migrational history compared to close-in objects. The sample of long-period exoplanets with well determined masses and radii is still limited, but a growing number of long-period objects reveal themselves in the TESS data. Our goal is to vet and confirm single transit planet candidates detected in the TESS space-based photometric data through spectroscopic and photometric follow up observations with ground-based instruments. We use the Next Generation Transit Survey (NGTS) to photometrically monitor the candidates in order to observe additional transits. We report the discovery of two massive, warm Jupiter-size planets, one orbiting the F8-type star TOI-5153 and the other orbiting the G1-type star NGTS-20 (=TOI-5152). From our spectroscopic analysis, both stars are metal-rich with a metallicity of 0.12 and 0.15, respectively. Follow-up radial velocity observations were carried out with CORALIE, CHIRON, FEROS, and HARPS. TOI-5153 hosts a 20.33 day period planet with a planetary mass of 3.26 (+-0.18) Mj, a radius of 1.06 (+-0.04) Rj , and an orbital eccentricity of 0.091 (+-0.026). NGTS-20 b is a 2.98 (+-0.16) Mj planet with a radius of 1.07 (+-0.04) Rj on an eccentric (0.432 +- 0.023) orbit with an orbital period of 54.19 days. Both planets are metal-enriched and their heavy element content is in line with the previously reported mass-metallicity relation for gas giants. Both warm Jupiters orbit moderately bright host stars making these objects valuable targets for follow-up studies of the planetary atmosphere and measurement of the spin-orbit angle of the system.

The Atacama Large Aperture Submillimeter Telescope (AtLAST) is a concept for a 50m class single-dish telescope that will provide high sensitivity, fast mapping of the (sub-)millimeter sky. Expected to be powered by renewable energy sources, and to be constructed in the Atacama desert in the 2030s, AtLAST's suite of up to six state-of-the-art instruments will take advantage of its large field of view and high throughput to deliver efficient continuum and spectroscopic observations of the faint, large-scale emission that eludes current facilities. Here we present the key science drivers for the telescope characteristics, and discuss constraints that the transformational science goals place on future instrumentation.

Centaurus X-4 (Cen X-4) is a relatively nearby neutron star low-mass X-ray binary that showed outbursts in 1969 and 1979, but has not shown a full outburst since. Due to its proximity and sustained period of quiescence, it is a prime target to study the coupling between accretion and jet ejection in quiescent neutron star low-mass X-ray binaries. Here, we present four MeerKAT radio observations at 1.3 GHz of Cen X-4, combined with NICER and Swift X-ray monitoring. During the first and most sensitive observation, Cen X-4 was in a fully quiescent X-ray state. The three later and shorter observations targeted a brief period of faint X-ray activity in January 2021, which has been referred to as a 'mis-fired' outburst. Cen X-4 is not detected in any of the four MeerKAT observations. We place these radio non-detections on the X-ray -- radio luminosity diagram, improving the constraints on the correlation between the two luminosities from earlier quiescent radio studies. We confirm that Cen X-4 is radio fainter than the transitional milli-second pulsar PSR J1023+0038 at the same X-ray luminosity. We discuss the radio behaviour of accreting neutron stars at low X-ray luminosity more generally and finally comment on future observing campaigns.

We analyze the galaxy pairs in a set of volume limited samples from the SDSS to study the effects of minor interactions on the star formation rate (SFR) and colour of galaxies. We carefully design control samples of the isolated galaxies by matching the stellar mass and redshift of the minor pairs. The SFR distributions and colour distributions in the minor pairs differ from their controls at $>99\%$ significance level. We also simultaneously match the control galaxies in stellar mass, redshift and local density to assess the role of the environment. The null hypothesis can be rejected at $>99\%$ confidence level even after matching the environment. Our analysis shows that the minor interactions quench galaxies in the present Universe. The degree of quenching decreases with the increasing pair separation and plateaus beyond 50 kpc. Combining data from the Galaxy Zoo and Galaxy Zoo2, we find that only $\sim 1\%$ galaxies have a dominant bulge, $4\%-7\%$ galaxies host a bar, and $5\%-10\%$ galaxies show the AGN activity in minor pairs. The quenching in minor pairs can not be entirely explained by their environment and the presence of bar, bulge or AGN. The more massive companion satisfies the criteria for mass quenching in most of the minor pairs. We propose that the stripping and starvation likely caused the quenching in the less massive companion at a later stage of evolution.

We measure the role of major and minor mergers in forming the stellar masses of galaxies over $0<z<3$ using a combination of $\sim 3.25$ deg$^{2}$ of the deepest ground based near-infrared imaging taken to date as part of the REFINE survey. We measure the pair fraction and merger fractions for galaxy mergers of different mass ratios, and quantify the merger rate with newly measured time-scales derived from the Illustris simulation as a function of redshift and merger mass ratio. We find that over $0 < z < 3$ major mergers with mass ratios greater than 1:4 occur $0.85^{+0.19}_{-0.20}$ times on average, while minor mergers down to ratios of 1:10 occur on average $1.43^{+0.5}_{-0.3}$ times per galaxy. We also quantify the role of major and minor mergers in galaxy formation, whereby the increase in mass due to major mergers is $93^{+49}_{-31}$% while minor mergers account for an increase of $29^{+17}_{-12}$%; thus major mergers add more stellar mass to galaxies than minor mergers over this epoch. Overall, mergers will more than double the mass of massive galaxies over this epoch. Finally, we compare our results to simulations, finding that minor mergers are over predicted in Illustris and in semi-analytical models, suggesting a mismatch between observations and theory in this fundamental aspect of galaxy assembly.

Spectrogram classification plays an important role in analyzing gravitational wave data. In this paper, we propose a framework to improve the classification performance by using Generative Adversarial Networks (GANs). As substantial efforts and expertise are required to annotate spectrograms, the number of training examples is very limited. However, it is well known that deep networks can perform well only when the sample size of the training set is sufficiently large. Furthermore, the imbalanced sample sizes in different classes can also hamper the performance. In order to tackle these problems, we propose a GAN-based data augmentation framework. While standard data augmentation methods for conventional images cannot be applied on spectrograms, we found that a variant of GANs, ProGAN, is capable of generating high-resolution spectrograms which are consistent with the quality of the high-resolution original images and provide a desirable diversity. We have validated our framework by classifying glitches in the {\it Gravity Spy} dataset with the GAN-generated spectrograms for training. We show that the proposed method can provide an alternative to transfer learning for the classification of spectrograms using deep networks, i.e. using a high-resolution GAN for data augmentation instead. Furthermore, fluctuations in classification performance with small sample sizes for training and evaluation can be greatly reduced. Using the trained network in our framework, we have also examined the spectrograms with label anomalies in {\it Gravity Spy}.

The dynamical evolution of the solar system is chaotic with a Lyapunov time of only $\sim$5 Myr for the inner planets. Due to the chaos it is fundamentally impossible to accurately predict the solar system's orbital evolution beyond $\sim$50 Myr based on present astronomical observations. We have recently developed a method to overcome the problem by using the geologic record to constrain astronomical solutions in the past. Our resulting optimal astronomical solution (called ZB18a) shows exceptional agreement with the geologic record to $\sim$58 Ma (Myr ago) and a characteristic resonance transition around 50 Ma. Here we show that ZB18a and integration of Earth's and Mars' spin vector based on ZB18a yield reduced variations in Earth's and Mars' orbital inclination and Earth's obliquity (axial tilt) from $\sim$58 to $\sim$48 Ma -- the latter being consistent with paleoclimate records. The changes in the obliquities have important implications for the climate histories of Earth and Mars. We provide a detailed analysis of solar system frequencies ($g$- and $s$-modes) and show that the shifts in the variation in Earth's and Mars' orbital inclination and obliquity around 48 Ma are associated with the resonance transition and caused by changes in the contributions to the superposition of $s$-modes, plus $g$-$s$-mode interactions in the inner solar system. The $g$-$s$-mode interactions and the resonance transition (consistent with geologic data) are unequivocal manifestations of chaos. Dynamical chaos in the solar system hence not only affects its orbital properties, but also the long-term evolution of planetary climate through eccentricity and the link between inclination and axial tilt.

Diffusive TeV gamma-ray emissions have been recently discovered extending beyond the pulsar wind nebulae of a few middle-aged pulsars, implying that energetic electron/positron pairs are escaping from the pulsar wind nebulae and radiating in the ambient interstellar medium. It has been suggested that these extended emissions constitute a distinct class of nonthermal sources, termed "pulsar halos". In this article, I will review the research progress on pulsar halos and discuss our current understanding on their physics, including the multiwavelength observations, different theoretical models, as well as implications for the origin of cosmic-ray positron excess and Galactic diffuse gamma-ray emission.

We present the first high-resolution chemical abundances of seven stars in the recently discovered high-energy dwarf galaxy stream Typhon. Typhon stars have apocenters reaching to ${\gtrsim}100$ kpc, making this the first detailed chemical picture of the Milky Way's very distant stellar halo. Typhon's chemical abundances are more like a dwarf galaxy than a globular cluster, showing a metallicity dispersion and no presence of multiple stellar populations. We find that Typhon stars display enhanced $\alpha$-element abundances and increasing $r$-process abundances with increasing metallicity. The high-$\alpha$ abundances suggest a short star formation duration for Typhon, but this is at odds with expectations for the distant Milky Way halo and the presence of delayed $r$-process enrichment. If the progenitor of Typhon is indeed a new dwarf galaxy, possible scenarios explaining this apparent contradiction include a dynamical interaction within the Milky Way that increases Typhon's orbital energy, a burst of enhanced late-time star formation that raises [$\alpha$/Fe], and/or group preprocessing by another dwarf galaxy before infall into the Milky Way. An alternate explanation is that Typhon is the high-energy tail of a more massive disrupted dwarf galaxy that lost energy through dynamical friction. We cannot clearly identify a known low-energy progenitor of Typhon, but cosmological simulations give about 2:1 odds that Typhon is a high-energy tail of a massive galaxy instead of a new disrupted galaxy. Typhon's surprising combination of kinematics and chemistry thus underscores the need to fully characterize the dynamical history and detailed abundances of known substructures before identifying the origin of new substructures.

Local thermal instability can plausibly explain the formation of multiphase gas in many different astrophysical environments, but the theory is only well understood in the optically thin limit of the equations of radiation hydrodynamics (RHD). Here we lay groundwork for transitioning from this limit to a full RHD treatment assuming a gray opacity formalism. We consider a situation where the gas becomes thermally unstable due to the hardening of the radiation field when the main radiative processes are free-free cooling and Compton heating. We identify two ways in which this can happen: (i) when the Compton temperature increases with time, through a rise in either the intensity or energy of a hard X-ray component; and (ii) when attenuation reduces the flux of the thermal component so that the Compton temperature increases with depth through the slab. Both ways likely occur in the broad line region of active galactic nuclei where columns of gas can be ionization bounded. In such instances where attenuation is significant, thermal equilibrium solution curves become position-dependent and it no longer suffices to assess the stability of an irradiated column of gas at all depths using a single equilibrium curve. We demonstrate how to analyze a new equilibrium curve -- the attenuation curve -- for this purpose, and we show that by Field's instability criterion, a negative slope along this curve indicates that constant density slabs are thermally unstable whenever the gas temperature increases with depth.

Comparison of appropriate models to describe observational data is a fundamental task of science. The Bayesian model evidence, or marginal likelihood, is a computationally challenging, yet crucial, quantity to estimate to perform Bayesian model comparison. We introduce a methodology to compute the Bayesian model evidence in simulation-based inference (SBI) scenarios (also often called likelihood-free inference). In particular, we leverage the recently proposed learnt harmonic mean estimator and exploit the fact that it is decoupled from the method used to generate posterior samples, i.e. it requires posterior samples only, which may be generated by any approach. This flexibility, which is lacking in many alternative methods for computing the model evidence, allows us to develop SBI model comparison techniques for the three main neural density estimation approaches, including neural posterior estimation (NPE), neural likelihood estimation (NLE), and neural ratio estimation (NRE). We demonstrate and validate our SBI evidence calculation techniques on a range of inference problems, including a gravitational wave example. Moreover, we further validate the accuracy of the learnt harmonic mean estimator, implemented in the HARMONIC software, in likelihood-based settings. These results highlight the potential of HARMONIC as a sampler-agnostic method to estimate the model evidence in both likelihood-based and simulation-based scenarios.

The bias of dark matter halos and galaxies is a crucial quantity in many cosmological analyses. In this work, using large cosmological simulations, we explore the halo mass function and halo bias within cosmic voids. For the first time to date, we show that they are scale-dependent along the void profile, and provide a predictive theoretical model of both the halo mass function and halo bias inside voids, recovering for the latter and 1% accuracy against simulated data. These findings may help shed light on the dynamics of halo formation within voids and improve the analysis of several void statistics from ongoing and upcoming galaxy surveys.

Biological molecules chose one of two structurally, chiral systems which are related by reflection in a mirror. It is proposed that this choice was made, causally, by magnetically polarized and physically chiral cosmic-rays, which are known to have a large role in mutagenesis. It is shown that the cosmic rays can impose a small, but persistent, chiral bias in the rate at which they induce structural changes in simple, chiral monomers that are the building blocks of biopolymers. A much larger effect should be present with helical biopolymers, in particular, those that may have been the progenitors of RNA and DNA. It is shown that the interaction can be both electrostatic, just involving the molecular electric field, and electromagnetic, also involving a magnetic field. It is argued that this bias can lead to the emergence of a single, chiral life form over an evolutionary timescale. If this mechanism dominates, then the handedness of living systems should be universal. Experiments are proposed to assess the efficacy of this process.

The flavor evolution of neutrinos in core collapse supernovae and neutron star mergers is a critically important unsolved problem in astrophysics. Following the electron flavor evolution of the neutrino system is essential for calculating the thermodynamics of compact objects as well as the chemical elements they produce. Accurately accounting for flavor transformation in these environments is challenging for a number of reasons, including the large number of neutrinos involved, the small spatial scale of the oscillation, and the nonlinearity of the system. We take a step in addressing these issues by presenting a method which describes the neutrino fields in terms of angular moments. Our moment method successfully describes the fast flavor neutrino transformation phenomenon which is expected to occur in regions close to the central object. We apply our moment method to neutron star merger conditions and show that we are able to capture the three phases of growth, saturation, and decoherence by comparing with particle-in-cell calculations. We also determine the size of the growing fluctuations in the neutrino field.

Quasicircular binary black hole mergers are described by 15 parameters, of which gravitational wave observations can typically constrain only $\sim 10$ independent combinations to varying degree. In this work, we devise coordinates that remove correlations, and disentangle well- and poorly-measured quantities. Additionally, we identify approximate discrete symmetries in the posterior as the primary cause of multimodality, and design a method to tackle this type of multimodality. The resulting posteriors have little structure and can be sampled efficiently and robustly. We provide a Python package for parameter estimation, cogwheel, that implements these methods together with other algorithms for accelerating the inference process. One of the coordinates we introduce is a spin azimuth that can be measured remarkably well in the presence of orbital precession, and we anticipate that this will shed light on the occurrence of spin-orbit misalignment in nature.

The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA. This Letter reports results from LZ's first search for Weakly Interacting Massive Particles (WIMPs) with an exposure of 60 live days using a fiducial mass of 5.5 t. A profile-likelihood analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon cross-sections for WIMP masses above 9 GeV/c$^2$. The most stringent limit is set at 30 GeV/c$^2$, excluding cross sections above 5.9$\times 10^{-48}$ cm$^2$ at the 90% confidence level.

The recent transition from decelerated to accelerated expansion can be seen as a reflection (or ``bounce'') in the connection variable, defined by the inverse comoving Hubble length ($b=\dot a$, on-shell). We study the quantum cosmology of this process. We use a formalism for obtaining relational time variables either through the demotion of the constants of Nature to integration constants, or by identifying fluid constants of motion. We extend its previous application to a toy model (radiation and $\Lambda$) to the realistic setting of a transition from dust matter to $\Lambda$ domination. In the dust and $\Lambda$ model two time variables may be defined, conjugate to $\Lambda$ and to the dust constant of motion, and we work out the monochromatic solutions to the Schr\"odinger equation representing the Hamiltonian constraint. As for their radiation and $\Lambda$ counterparts, these solutions exhibit ``ringing'', whereby the incident and reflected waves interfere, leading to oscillations in the amplitude. In the semi-classical approximation we find that, close to the bounce, the probability distribution becomes double-peaked, one peak following a trajectory close to the classical limit but with a Hubble parameter slightly shifted downwards, the other with a value of $b$ stuck at its minimum $b=b_\star$. Still closer to the transition, the distribution is better approximated by an exponential distribution, with a single peak at $b=b_\star$, and a (more representative) average $b$ biased towards a value higher than the classical trajectory. Thus, we obtain a distinctive prediction for the average Hubble parameter with redshift: slightly lower than its classical value when $z\approx 0$, but potentially much higher than the classical prediction around $z\sim 0.64$, where the bounce most likely occurred. The implications for the ``Hubble tension'' have not escaped us.

The neutrino propagation and oscillations in various gravitational fields are studied. First, we consider the neutrino scattering off a black hole accounting for the neutrino spin precession. Then, we study the evolution of flavor neutrinos in stochastic gravitational waves. The astrophysical applications of the obtained results are considered.

We study black holes in a modified gravity scenario involving a scalar field quadratically coupled to the Gauss-Bonnet invariant. The scalar is assumed to be in a spontaneously broken phase at spatial infinity due to a bare Higgs-like potential. For a proper choice of sign, the non-minimal coupling to gravity leads to symmetry restoration near the black hole horizon, prompting the development of the scalar wall in its vicinity. The wall thickness depends on the bare mass of the scalar and can be much smaller than the Schwarzschild radius. In a weakly coupled regime, the quadratic coupling to the Gauss-Bonnet invariant effectively becomes linear, and no walls are formed. We find approximate analytical solutions for the scalar field in the test field regime, and obtain numerically static black hole solutions within this setup. We discuss cosmological implications of the model and show that it is fully consistent with the existence of an inflationary stage, unlike the spontaneous scalarization scenario assuming the opposite sign of the non-minimal coupling to gravity.

In the limit of large magnetic Reynolds numbers, it is shown that a smooth differential rotation can lead to fast dynamo action, provided that the electrical conductivity or magnetic permeability is anisotropic. If the shear is infinite, for example between two rotating solid bodies, the anisotropic dynamo becomes furious, meaning that the magnetic growth rate increases toward infinity with an increasing magnetic Reynolds number.

We show how to use matrix methods of quantum mechanics to efficiently and accurately calculate axially symmetric radiation transfer in clouds, with conservative scattering of arbitrary anisotropy. Analyses of conservative scattering, where the single scattering albedo is $\tilde\omega =1$ and no energy is exchanged between the radiation and scatterers, began with work by Schwarzschild, Milne, Eddington and others on radiative transfer in stars. There the scattering is isotropic or nearly so. It has been difficult to extend traditional methods to highly anisotropic scattering, like that of sunlight in Earth's clouds. The $2n$-stream method described here is a practical way to handle highly anisotropic, conservative scattering. The basic ideas of the $2n$-stream method are an extension of Wick's seminal work on transport of thermal neutrons by isotropic scattering to scattering with arbitrary anisotropy. How to do this for finite absorption and $\tilde\omega<1$ was described in our previous paper (arXiv:2205.09713v2). But those methods fail for conservative scattering, when $\tilde \omega = 1$. Here we show that minor modifications to the fundamental $2n$-scattering theory for $\tilde\omega <1$ make it suitable for $\tilde\omega = 1$.