Papers for Wednesday, Jul 19 2023

The chemical evolution history of the Small Magellanic Cloud (SMC) has been a matter of debate for decades. The challenges in understanding the SMC chemical evolution are related to a very slow star formation rate (SFR) combined with bursts triggered by the multiple interactions between the SMC and the Large Magellanic Cloud, a significant (~0.5 dex) metallicity dispersion for the SMC cluster population younger than about 7.5 Gyr, and multiple chemical evolution models tracing very different paths through the observed age-metallicity relation of the SMC. There is no doubt that these processes were complex. Therefore, a step-by-step strategy is required in order to better understand the SMC chemical evolution. We adopted an existing framework to split the SMC into regions on the sky, and we focus on the west halo in this work, which contains the oldest and most metal-poor stellar populations and is moving away from the SMC, that is, in an opposite motion with respect to the Magellanic Bridge. We present a sample containing ~60% of all west halo clusters to represent the region well, and we identify a clear age-metallicity relation with a tight dispersion that exhibits a 0.5 dex metallicity dip about 6 Gyr ago. We ran chemical evolution models and discuss possible scenarios to explain this metallicity dip, the most likely being a major merger accelerating the SFR after the event. This merger should be combined with inefficient internal gas mixing within the SMC and different SFRs in different SMC regions because the same metallicity dip is not seen in the AMR of the SMC combining clusters from all regions. We try to explain the scenario to better understand the SMC chemo-dynamical history.

This study uses archival high frequency continuum data to expand the search for Hypercompact HII regions and determine the conditions at which they appear, as this stage high mass star formation is short-lived and rare. We use 23 GHz continuum data taken towards methanol masers, which are an excellent signpost for very young embedded high-mass protostars. We have searched for high-frequency, optically thick radio sources to identify HC HII region candidates. The data cover 128 fields that include 141 methanol masers identified by the Methanol Multibeam (MMB) survey. We have detected 68 high-frequency radio sources and conducted a multi-wavelength analysis to determine their nature. This has identified 49 HII regions, 47 of which are embedded in dense clumps fourteen of which do not have a 5 GHz radio counterpart. We have identified 13 methanol maser sites that are coincident with radio sources that have a steep positive spectral index. The majority of these are not detected in the mid-infrared and have been classified as protostellar or young stellar objects in the literature and we therefore consider to be good HC HII region candidates, however, further work and higher resolution data are needed to confirm these candidates.

The Sun is a bright gamma-ray source due to hadronic cosmic-ray interactions with solar gas. While it is known that incoming cosmic rays must generally first be reflected by solar magnetic fields to produce outgoing gamma rays, theoretical models have yet to reproduce the observed spectra. We introduce a simplified model of the solar magnetic fields that captures the main elements relevant to gamma-ray production. These are a flux tube, representing the network elements, and a flux sheet, representing the intergranule sheets. Both the tube and sheet have a horizontal size of order $100~{\rm km}$ and serve as sites where cosmic rays are reflected and gamma rays are produced. Despite having no tuning to match gamma-ray data, our model produces a gamma-ray spectrum that reasonably matches both the hard spectrum seen by Fermi-LAT data at $\text{1--200}~{\rm GeV}$ and the considerably softer spectrum seen by HAWC at near $10^3~{\rm GeV}$. We show that lower-energy ($\lesssim 10~{\rm GeV}$) gamma rays are primarily produced in the network elements and higher-energy ($\gtrsim {\rm few} \times 10~{\rm GeV}$) gamma rays in the intergranule sheets. Notably, the spectrum softening observed by HAWC results from the limited effectiveness of capturing and reflecting $\sim 10^4~{\rm GeV}$ cosmic rays by the finite-sized intergranule sheets. Our study is important for understanding cosmic-ray transport in the solar atmosphere and will lead to insights about small-scale magnetic fields in the quiet photosphere.

Forthcoming imaging surveys will potentially increase the number of known galaxy-scale strong lenses by several orders of magnitude. For this to happen, images of tens of millions of galaxies will have to be inspected to identify potential candidates. In this context, deep learning techniques are particularly suitable for the finding patterns in large data sets, and convolutional neural networks (CNNs) in particular can efficiently process large volumes of images. We assess and compare the performance of three network architectures in the classification of strong lensing systems on the basis of their morphological characteristics. We train and test our models on different subsamples of a data set of forty thousand mock images, having characteristics similar to those expected in the wide survey planned with the ESA mission \Euclid, gradually including larger fractions of faint lenses. We also evaluate the importance of adding information about the colour difference between the lens and source galaxies by repeating the same training on single-band and multi-band images. Our models find samples of clear lenses with $\gtrsim 90\%$ precision and completeness, without significant differences in the performance of the three architectures. Nevertheless, when including lenses with fainter arcs in the training set, the three models' performance deteriorates with accuracy values of $\sim 0.87$ to $\sim 0.75$ depending on the model. Our analysis confirms the potential of the application of CNNs to the identification of galaxy-scale strong lenses. We suggest that specific training with separate classes of lenses might be needed for detecting the faint lenses since the addition of the colour information does not yield a significant improvement in the current analysis, with the accuracy ranging from $\sim 0.89$ to $\sim 0.78$ for the different models.

We report the discovery of two ultra-faint dwarf galaxies, Leo M and Leo K, that lie outside the halo of the Milky Way. Using Hubble Space Telescope imaging of the resolved stars, we create color-magnitude diagrams reaching the old main sequence turn-off of each system and (i) fit for structural parameters of the galaxies; (ii) measure their distances using the luminosity of the Horizontal Branch stars; (iii) estimate integrated magnitudes and stellar masses; and (iv) reconstruct the star formation histories. Based on their location in the Local Group, neither galaxy is currently a satellite of the Milky Way, although Leo K is located ~22 kpc from the low-mass galaxy Leo T and these two systems may have had a past interaction. Leo M and Leo K have stellar masses of 1.5+/-0.2 x 10^4 Msun and 1.0+/-0.2 x 10^4 Msun, and were quenched 10.9 (+1.8/-0.6) Gyr and 12.6 (+0.2/-5.8) Gyr ago, respectively. Given that the galaxies are not satellites of the MW, it is unlikely that they were quenched by environmental processing. Instead, such low masses and early quenching timescales are consistent with the scenario that a combination of reionization and stellar feedback shut down star formation at early cosmic times.

The recent supernova, SN 2023ixf, one of the closest observed type II SNe has revealed the presence of a dense circumstellar material (CSM). Interaction of the SN ejecta with this dense CSM may create high energy protons of PeV energies through shock acceleration. These accelerated protons then colliding with the CSM (inelastic $pp$ collision) can produce secondaries such as high energy gamma-rays and neutrinos. However, no gamma-rays and neutrinos have been detected by Fermi-LAT and IceCube from this event. Indeed, Fermi-LAT has placed an upper limits on the gamma-ray flux above $100$~MeV to be $2.6 \times 10^{-11}~\rm erg~cm^{-2}~s^{-1}$. On the other hand IceCube's upper limit on muon neutrino flux is $7.3\times 10^{-2} ~\rm GeV~cm^{-2}$. Using these experimental constraints and shock-CSM properties derived from observations, we obtain new upper limits on the gamma-ray ($10^{-11}~\rm erg~cm^{-2}~s^{-1}$) and neutrino ($10^{-3}~\rm GeV~cm^{-2}$) fluxes from SN 2023ixf produced via the $pp$ interaction channel. While we found the gamma-ray flux to be consistent with Fermi-LAT's upper limit, the neutrino flux is found to be about $2$ order smaller than the IceCube's upper limit. We further analyse detection prospects of such secondary signals from future SN 2023 like events with upcoming detectors, CTA and IceCube-Gen2 and found to have great discovery potential, if any event occurs within $7$ Mpc.

To what extent magnetic fields affect how molecular clouds (MCs) fragment and create dense structures is an open question. We present a numerical study of cloud fragmentation using the SILCC-Zoom simulations. These simulations follow the self-consistent formation of MCs in a few hundred parsec sized region of a stratified galactic disc; and include magnetic fields, self-gravity, supernova-driven turbulence, as well as a non-equilibrium chemical network. To discern the role of magnetic fields in the evolution of MCs, we study seven simulated clouds, five with magnetic fields, and two without, with a maximum resolution of 0.1 parsec. Using a dendrogram we identify hierarchical structures which form within the clouds. Overall, the magnetised clouds have more mass in a diffuse envelope with a number density between 1-100 cm$^{-3}$. We find that six out of seven clouds are sheet-like on the largest scales, as also found in recent observations, and with filamentary structures embedded within, consistent with the bubble-driven MC formation mechanism. Hydrodynamic simulations tend to produce more sheet-like structures also on smaller scales, while the presence of magnetic fields promotes filament formation. Analysing cloud energetics, we find that magnetic fields are dynamically important for less dense, mostly but not exclusively atomic structures (typically up to $\sim 100 - 1000$~cm$^{-3}$), while the denser, potentially star-forming structures are energetically dominated by self-gravity and turbulence. In addition, we compute the magnetic surface term and demonstrate that it is generally confining, and some atomic structures are even magnetically held together. In general, magnetic fields delay the cloud evolution and fragmentation by $\sim$ 1 Myr.

The use of galaxy clusters as cosmological probes relies on a detailed understanding of their properties. We aim to update the spectroscopic cluster identification of CODEX by running the spectroscopic group finder on the follow-up spectroscopy results and connecting the dynamical state of clusters to their scaling relations. We implemented a reproducible spectroscopic membership determination and cleaning procedures, based on the redMaPPer membership, running the spectroscopic group finder on the follow-up spectroscopy results and cleaning the membership for spectroscopic outliers. We applied the Anderson-Darling test for velocity substructure and analysed its influence on the scaling relations. We also tested the effect of the X-ray-to-optical centre offset on the scaling relations. We report on the scaling relations between richness, X-ray luminosity, and velocity dispersion for a complete sample of clusters with at least 15 members. Clusters with velocity substructure exhibit enhanced velocity dispersion for a given richness and are characterized by 2.5 times larger scatter. Clusters that have a strong offset in X-ray-to-optical centres have comparable scaling relations as clusters with substructure. We demonstrate that there is a consistency in the parameters of the scaling relations for the low- and high-richness galaxy clusters. Splitting the clusters by redshift, we note a decrease in scatter with redshift in all scaling relations. We localize the redshift range where a high scatter is observed to $z<0.15$, which is in agreement with the literature results on the scatter. We note that the increase in scatter for both high- and low-luminosity clusters is $z<0.15$, suggesting that both cooling and the resulting active galactic nucleus feedback are at the root of this scatter. Abridged.

Efforts to spectrally characterize the atmospheric compositions of temperate terrestrial exoplanets orbiting M-dwarf stars with the James Webb Space Telescope (JWST) are now underway. Key molecular targets of such searches include O$_2$ and CO, which are potential indicators of life. Recently, it was proposed that CO$_2$ photolysis generates abundant ($\gtrsim0.1$ bar) abiotic O$_2$ and CO in the atmospheres of habitable M-dwarf planets with CO$_2$-rich atmospheres, constituting a strong false positive for O$_2$ as a biosignature and further complicating efforts to use CO as a diagnostic of surface biology. Significantly, this implied that TRAPPIST-1e and TRAPPIST-1f, now under observation with JWST, would abiotically accumulate abundant O$_2$ and CO, if habitable. Here, we use a multi-model approach to re-examine photochemical O$_2$ and CO accumulation on planets orbiting M-dwarf stars. We show that photochemical O$_2$ remains a trace gas on habitable CO$_2$-rich M-dwarf planets, with earlier predictions of abundant O$_2$ and CO due to an atmospheric model top that was too low to accurately resolve the unusually-high CO$_2$ photolysis peak on such worlds. Our work strengthens the case for O$_2$ as a biosignature gas, and affirms the importance of CO as a diagnostic of photochemical O$_2$ production. However, observationally relevant false positive potential remains, especially for O$_2$'s photochemical product O$_3$, and further work is required to confidently understand O$_2$ and O$_3$ as biosignature gases on M-dwarf planets.

Stellar ages are critical building blocks of evolutionary models, but challenging to measure for low mass main sequence stars. An unexplored solution in this regime is the application of probabilistic machine learning methods to gyrochronology, a stellar dating technique that is uniquely well suited for these stars. While accurate analytical gyrochronological models have proven challenging to develop, here we apply conditional normalizing flows to photometric data from open star clusters, and demonstrate that a data-driven approach can constrain gyrochronological ages with a precision comparable to other standard techniques. We evaluate the flow results in the context of a Bayesian framework, and show that our inferred ages recover literature values well. This work demonstrates the potential of a probabilistic data-driven solution to widen the applicability of gyrochronological stellar dating.

We study supermassive black hole (SMBH) binary eccentricity of equal-mass galaxy mergers in $N$-body simulations with the KETJU code, which combines the GADGET-4 fast multipole gravity solver with accurate regularized integration and Post-Newtonian corrections around SMBHs. In simulations with realistic, high eccentricity galactic merger orbits, the binary eccentricity is found to be a non-linear function of the deflection angle in the SMBH orbit during the final, nearly radial close encounter between the SMBHs before they form a bound binary. This mapping between the deflection angle and the binary eccentricity has no apparent resolution dependence in our simulations spanning the resolution range of $1\times10^5 - 8\times10^6$ particles per galaxy. The mapping is also captured using a simple model with an analytic potential, indicating that it is driven by the interplay between a smooth asymmetric stellar background potential and dynamical friction acting on the SMBHs. Due to the non-linearity of this mapping, in certain merger configurations small, parsec-scale variations in the merger orbit can result in binary eccentricities varying in nearly the full possible range between $e=0$ and $e=1$. In idealized simulations, such variations are caused by finite resolution effects, and convergence of the binary eccentricity can be achieved with increasing resolution. However, in real galaxies, other mechanisms such as nuclear gas and substructure that perturb the merger orbit are likely to be significant enough for the binary eccentricity to be effectively random. Our results indicate that the distribution of these effectively random eccentricities can be studied using even moderate resolution simulations.

Close-in planets undergo strong tidal interactions with the parent star that modify their spins and orbits. In the two-body problem, the final stage for tidal evolution is the synchronisation of the rotation and orbital periods, and the alignment of the planet spin axis with the normal to the orbit (zero planet obliquity). The orbital eccentricity is also damped to zero, but over a much longer timescale, that may exceed the lifetime of the system. For non-zero eccentricities, the rotation rate can be trapped in spin-orbit resonances that delay the evolution towards the synchronous state. Here we show that capture in some spin-orbit resonances may also excite the obliquity to high values rather than damp it to zero. Depending on the system parameters, obliquities of 60 to 80 degrees can be maintained throughout the entire lifetime of the planet. This unexpected behaviour is particularly important for Earth-like planets in the habitable zone of M-dwarf stars, as it may help to sustain temperate environments and thus more favourable conditions for life.

We compile a catalog of 598 highly probable and 79 likely red supergiants (RSGs) of the Milky Way, which represents the largest list of Galactic RSG candidates to date. We matched distances measured by Gaia DR3, 2MASS photometry, and a 3D Galactic dust map to obtain luminous bright late-type stars. Determining the stars' bolometric luminosities and effective temperatures, we compared to Geneva stellar evolution tracks to determine likely RSG candidates, and quantified contamination using a catalog of Galactic AGB in the same luminosity-temperature space. We add details for common or interesting characteristics of RSG, such as multi-star system membership, variability, and classification as a runaway. As potential future core-collapse supernova (SN) progenitors, we studied the ability of the catalog to inform the Supernova Early Warning System (SNEWS) coincidence network made to automate pointing, and show that for 3D position estimates made possible by neutrinos, the number of progenitor candidates can be significantly reduced, improving our ability to observe the progenitor pre-explosion and the early phases of the core-collapse supernova.

To date, the search for radio technosignatures has focused on sky location as a primary discriminant between technosignature candidates and anthropogenic radio frequency interference (RFI). In this work, we investigate the possibility of searching for technosignatures by identifying the presence and nature of intensity scintillations arising from the turbulent, ionized plasma of the interstellar medium (ISM). Past works have detailed how interstellar scattering can both enhance and diminish the detectability of narrowband radio signals. We use the NE2001 Galactic free electron density model to estimate scintillation timescales to which narrowband signal searches would be sensitive, and discuss ways in which we might practically detect strong intensity scintillations in detected signals. We further analyze the RFI environment of the Robert C. Byrd Green Bank Telescope (GBT) with the proposed methodology and comment on the feasibility of using scintillation as a filter for technosignature candidates.

Gaia21bty, a pre-main sequence star that previously had shown aperiodic dips in its light curve, underwent a considerable $\Delta G\approx2.9$ mag brightening that occurred over a few months between 2020 October - 2021 February. The Gaia lightcurve shows that the star remained near maximum brightness for about $4-6$ months, and then started slowly fading over the next 2 years, with at least three superimposed $\sim$1 mag sudden rebrightening events. Whereas the amplitude and duration of the maximum is typical for EXors, optical and near-infrared spectra obtained at the maximum are dominated by features which are typical for FUors. Modelling of the accretion disc at the maximum indicates that the disc bolometric luminosity is 43 L$_{\odot}$ and the mass accretion rate is $2.5\times10^{-5}$ M$_{\odot}$ yr$^{-1}$, which are typical values for FUors even considering the large uncertainty in the distance ($1.7_{-0.4}^{+0.8}$ kpc). Further monitoring is necessary to understand the cause of the quick brightness decline, the rebrightening, and the other post-outburst light changes, as our multi-colour photometric data suggest that they could be caused by a long and discontinuous obscuration event. We speculate that the outburst might have induced large-scale inhomogeneous dust condensations in the line of sight leading to such phenomena, whilst the FUor outburst continues behind the opaque screen.

Multiwavelength observations are now the norm for studying blazars' various states of activity, classifying them, and determining possible underlying physical processes driving their emission. Broadband emission models became unavoidable tools for testing emission scenarios and setting values to physical quantities such as the magnetic field strength, Doppler factor, or shape of the particle distribution of the emission zone(s). We announce here the first public release of a new tool, Bjet_MCMC, that can automatically fit broadband spectral energy distributions (SEDs) of blazars. The complete code is available on GitHub and allows testing leptonic synchrotron self-Compton models (SSC), with or without external inverse-Compton processes from the thermal environment of supermassive black holes (accretion disk and broad line region). The code is designed to be user-friendly and computationally efficient. It contains a core written in C++ and a fully parallelized SED fitting method. The original multi-SSC zones model of Bjet is also available on GitHub but is not included in the MCMC fitting process at the moment. We present the features, performance, and results of Bjet_MCMC, as well as user advice.

Rebirth of X-ray polarimetric instruments will have a significant impact on our knowledge of compact accreting sources. The properties of inner-accreting regions of active galactic nuclei (AGNs) or X-ray binary systems (XRBs), such as black-hole spin, their disc inclination and orientation, shape and size of their corona, can be polarimetrically studied, parallelly to the well-known X-ray spectroscopic and timing techniques. In this work, we provide a new spectropolarimetric numerical estimate of X-rays in the lamp-post coronal model for a distant observer, including a polarized reflected radiation from the accretion disc. The local disc reflection was simulated using the codes TITAN and STOKES and includes variable disc ionization as well as Monte Carlo treatment of Compton multiple scatterings. We introduce a relativistic code KYNSTOKES based on our well-tested KY package that accounts for all relativistic effects on radiation near a black hole, apart from the returning radiation, and adds a possibility of polarized coronal emission. We study the spectrum, polarization degree and polarization angle at spatial infinity for various global system parameters and we demonstrate the difference at infinity, if analytical local reflection computations are used. We newly predict that in the hard X-rays the reflected component can be 25% polarized and the total emission can be 9% polarized in the most favourable, yet realistic configurations of radio-quiet AGNs. Thus, the relativistic disc reflection remains important for the interpretation of X-ray polarimetric observations.

We present a straightforward argument for why the luminous, hard state of black hole X-ray binaries (BHXRBs) cannot always be associated with a magnetically arrested accretion disc (MAD). It relies on three core premises: 1) that the type-C quasi-periodic oscillation (QPO) is best explained by Lense-Thirring (LT) precession of a tilted, inner, hot flow; 2) that observed optical and infrared (IR) QPOs with the same or lower frequency as the type-C QPO suggest the jet, too, must precess in these systems; and 3) that numerical simulations of MADs show that their strong magnetic fields promote alignment of the disc with the black hole and, thereby, suppress LT precession. If all three premises hold true, then, at least whenever the optical and IR QPOs are observed alongside the type-C QPO, these systems cannot be in the MAD state. Extending the argument further, if the type-C QPO is always associated with LT precession, then it would rule out MADs anytime this timing feature is seen, which covers nearly all BHXRBs when they are in the luminous, hard and hard-intermediate states.

The power-law slope of the rest-UV continuum ($f_{\lambda}\propto\lambda^{\beta}$) is a key metric of early star forming galaxies, providing one of our only windows into the stellar populations and physical conditions of $z>10$ galaxies. Expanding upon previous studies with limited sample sizes, we leverage deep imaging from JADES to investigate the UV slopes of 179 $z>9$ galaxies with apparent magnitudes of $m_{\rm F200W}=26-31$, which display a median UV slope of $\beta=-2.4$. We compare to a statistical sample of $z=5-9$ galaxies, finding a shift toward bluer rest-UV colors at all $\rm~M_{UV}$. The most UV-luminous $z>9$ galaxies are significantly bluer than their lower-redshift counterparts, representing a dearth of moderately-red galaxies in the first $500~$Myr. At yet earlier times, the $z>11$ galaxy population exhibits very blue UV slopes, implying very low attenuation from dust. We identify a robust sample of 44 galaxies with $\beta<-2.8$, which have SEDs requiring models of density-bounded HII regions and median ionizing photon escape fractions of $0.51$ to reproduce. Their rest-optical colors imply that this sample has weaker emission lines (median $m_{\rm F356W}-m_{\rm F444W}=0.19$ mag) than typical galaxies (median $m_{\rm F356W}-m_{\rm F444W}=0.39$ mag), consistent with the inferred escape fractions. This sample has relatively low stellar masses (median $\log(M/M_{\odot})=7.5$), and specific star-formation rates (median$=79\rm/Gyr$) nearly twice that of our full sample (median$=44\rm/Gyr$), suggesting they are more common among systems experiencing a recent upturn in star formation. We demonstrate that the shutoff of star formation provides an alternative solution for modelling of extremely blue UV colors, making distinct predictions for the rest-optical emission of these galaxies. Future spectroscopy will be required to distinguish between these physical pictures.

We investigate the core-cusp problem of the $\Lambda$ cold dark matter ($\Lambda$CDM) scenario in the context of Modified Newtonian Dynamics (MOND) paradigm exploiting the concept of equivalent Newtonian system (ENS). By means of particle-mesh $N-$body simulations in MOND we explore processes of galaxy formation via cold dissipationless collapse or merging of smaller substructures. From the end states of our simulations we recover the associated ENS and study the properties of their dark matter halos. We compare the simulation results with simple analytical estimates with a family of $\gamma-$models. We find that the dark matter density of ENSs of most spherical cold collapses ha a markedly cored structure, in particular for the lowest values of the initial virial ratios. End states of some simulations with clumpy initial conditions have more complex profiles and some of their ENSs exhibit a moderate cusp, with logarithmic density slope always shallower than 1. These results seem to point towards the fact that the absence in most observed galaxies of a central DM cusp, at variance with what one would expect from theoretical and numerical arguments in $\Lambda$CDM, would be totally consistent in a MONDian description.

We investigate the formation and evolution of z=0 massive compact galaxies (MCGs) in the IllustrisTNG cosmological simulation. We found that, as in observations, MCGs are mainly old (median age $\sim 10.8$ Gyr), have super-solar metallicities (median $\log Z/Z_{\odot}\sim0.35$) and are $\alpha$-enhanced (median $[\alpha/Fe]\sim0.25$). The age distribution extends to younger ages, however, and a few MCGs are as young as $\sim7$ Gyr. In general, MCGs assemble their mass early and accrete low angular momentum gas, significantly increasing their mass while growing their size much slower. A small fraction of MCGs follow another evolutionary path, going through a compaction event, with their sizes shrinking by 40% or more. The accretion of low angular momentum gas leads to enhanced SMBH growth, and MCGs reach the threshold SMBH mass of $\log M_\mathrm{BH}\sim10^{8.5} M_\odot$ - when kinetic AGN feedback kicks in and quenches the galaxy - earlier than non-compact galaxies. Comparing MCGs to a sample of median-sized quiescent galaxies matched in effective velocity dispersion, we find that their accretion histories are very different. 71% of MCGs do not merge after quenching compared to 37% of median-sized quiescent galaxies. Moreover, tracing these populations back in time, we find that at least a third of median-sized quiescent galaxies do not have a compact progenitor, underscoring that both dry mergers and progenitor bias effects are responsible for the differences in the kinematics and stellar population properties of MCGs and median-sized quiescent galaxies.

We have observed the Class 0/I protostellar system Ced110 IRS4 at an angular resolution of $0.05''$ ($\sim$10 au) as a part of the ALMA large program; Early Planet Formation in the Embedded Disks (eDisk). The 1.3 mm dust continuum emission reveals that Ced110 IRS4 is a binary system with a projected separation of $\sim$250 au. The continuum emissions associated with the main source and its companion, named Ced110 IRS4A and IRS4B respectively, exhibit disk-like shapes and likely arise from dust disks around the protostars. The continuum emission of Ced110 IRS4A has a radius of $\sim$110 au ($\sim0.6''$), and shows bumps along its major axis with an asymmetry. The bumps can be interpreted as an shallow, ring-like structure at a radius of $\sim$40 au ($\sim0.2''$) in the continuum emission, as demonstrated from two-dimensional intensity distribution models. A rotation curve analysis on the C$^{18}$O and $^{13}$CO $J=2$-1 lines reveals the presence of a Keplerian disk within a radius of 120 au around Ced110 IRS4A, which supports the interpretation that the dust continuum emission arises from a disk. The ring-like structure in the dust continuum emission might indicate a possible, annular substructure in the surface density of the embedded disk, although the possibility that it is an apparent structure due to the optically thick continuum emission cannot be ruled out.

SDSS J183131.63+420220.2 is an AM CVn-type cataclysmic variable. Using Asteroid Terrestrial-impact Last Alert System (ATLAS) and Zwicky Transient Facility (ZTF) data, I found that this object is actually a helium dwarf nova, which experienced a long (~6 yr) standstill (2017 to 2022). The object is currently (in 2023) in ER UMa-type state with supercycles of 20-30 d and large duty cycles exceeding 0.5. This object is the second known star among AM CVn stars having characteristics of ER UMa and Z Cam types. The long duration of the standstill phase is outstanding among helium dwarf novae. These observations indicate that the accretion disk in SDSS J183131.63+420220.2 is very close to thermal stability. I detected a period of 0.01602343(1) d in the ZTF data, which can be the orbital one. Combined with the case of MGAB-V240, the limit of thermal stability of the disks in AM CVn stars appears to be located around the orbital period of 0.0158-0.0160 d.

MeV nuclear de-excitation lines serve as a unique tool to study low-energy cosmic rays (CRs), containing both spectral and elemental information of the interacting material. In this paper, we estimated the possible nuclear de-excitation lines from the young supernova remnant Cassiopeia A. Given different CR spectral shapes and interacting materials, we found the predicted fluxes of strong narrow line emissions from the remnant are highly model-dependent, ranging from about $1\times10^{-10}\,{\rm \,cm^{-2}\,s^{-1}}$ to $1\times10^{-6}\, {\rm \,cm^{-2}\,s^{-1}}$ for the 4.44 MeV narrow line and from about $4\times10^{-11}\,{\rm \,cm^{-2}\,s^{-1}}$ to $2\times10^{-7}{\rm \,cm^{-2}\,s^{-1}}$ for the 6.13 MeV narrow line, respectively. Based on the new estimation, we also discussed the detection probability of these line emissions against the MeV diffuse Galactic background under different assumptions of instrument response functions.

Previous results suggest that there exists a correlation between the size of the bulge of a galaxy and the number of its dwarf galaxy satellites. This was found to be inconsistent with the standard model of cosmology based on comparisons to semi-analytical dark matter-only simulations, where no such correlation was found. In this work, we extend these studies using the volume-complete ELVES dwarf galaxy catalog, which increases the number of systems compared to previous work by a factor of four. For each giant galaxy we compile the bulge-to-total baryonic mass (B/T) ratio and put it as a function of the number of dwarf galaxies surrounding them within 250 kpc (N$_{250}$). For the 29 galaxy systems in the ELVES catalog, we find a linear relation between B/T and N$_{250}$ which is consistent with previous data. However, for a given stellar mass of the host galaxy this relation is mainly driven by their morphology, where early-type galaxies have a larger B/T ratio and a larger N$_{250}$ than late type galaxies. By investigating spiral galaxies in Illustris-TNG100, we tested whether the inclusion of baryons in the simulations will change the results based on Millennium-II. Contrary to dark matter-only simulations, we do find a correlation between B/T and N$_{250}$, indicating that the standard model of cosmology does predict a correlation. The empirical relation between the number of satellites and the bulge to total stellar mass is therefore not necessarily in tension with $\Lambda$CDM.

In the manuscript, a candidate of sub-pc binary black hole (BBH) system is reported in SDSS J1257+2023 through different properties of broad Balmer emission lines. After subtractions of host galaxy contributions, Gaussian functions are applied to measure emission lines in SDSS J1257+2023, leading line width (second moment) 760${\rm km/s}$ of broad H$\beta$ to be 0.69 times of line width 1100${\rm km/s}$ of broad H$\alpha$, quite different from normal line width ratio 1.1 of broad H$\beta$ to broad H$\alpha$ in quasars. The quite broader component in broad H$\alpha$ in SDSS J1257+2023 can be confirmed with confidence level higher than $5\sigma$ through F-test technique, through different model functions applied to measure emission lines. The broad Balmer emission lines having different line widths can be naturally explained by a BBH system with different obscurations on central two independent BLRs. Meanwhile, through ZTF light curves and corresponding phase folded light curves well described by sinusoidal function, BBH system expected optical QPOs can be detected with periodicity about 1000days, confirmed with confidence level higher than $3\sigma$ by Generalized Lomb-Scargle periodogram. And through CAR process simulated light curves, confidence level higher than $2\sigma$ can be determined to support the optical QPOs in SDSS J1257+2023 not from intrinsic AGN activities, although the ZTF light curves have short time durations. Moreover, through oversimplified BBH system simulated results, studying different broad Balmer lines as signs of BBH systems in normal quasars with flux ratios around 4 of broad H$\alpha$ to broad H$\beta$ could be done in near future.

The phenomenon of 1I/'Oumuamua introduced the interstellar object (ISO) class of celestial body into the astronomical lexicon, those objects with heliocentric speeds clearly in excess of that required to parabolically escape the Solar System - and therefore of extrasolar origin. A vogue topic at this moment in time is the possibility that some ISOs may impact with Earth, where they would be observed as bolides (meteor fireballs). There is the claim for instance that a meteor listed in the NASA-JPL CNEOS (Center for Near Earth Object Studies) database, CNEOS 2014-01-08 was interstellar, and additionally four further meteors from the database with interstellar origin have been proposed. This paper postulates that the origin of yet another meteor from this catalogue, CNEOS 2017-10-09 (observed over Bolivia, South America), was interstellar, as it may have been associated with 'Oumuamua. Note there is no direct velocity data for this object available, yet its observation time corresponds to the expected arrival time of an object ejected from 'Oumuamua and intersecting Earth's orbital position.

Observations of compact objects in Galactic binaries have provided tentative evidence of a dearth of masses in the so-called lower mass gap $\sim2.2-5$ M$_\odot$. Nevertheless, two such objects have been discovered in gravitational-wave data from LIGO and Virgo. Remarkably, the estimated masses of both secondaries in the coalescences GW190814 ($m_2=2.59^{+0.08}_{-0.09}$M$_\odot$) and GW200210_092254 ($m_2=2.83^{+0.47}_{-0.42}$M$_\odot$) fall near the total mass of $\sim 2.6$ M$_\odot$ of observed Galactic binary neutron star systems. The more massive components of the two binaries also have similar masses. Here we show that a neutron star merger origin of the lighter components in GW190814 and GW200210_092254 is favored over $M^{-2.3}$ (Bayes factor $\mathcal{B}\sim 5$) and uniform ($\mathcal{B}\sim 14$) mass distributions in the lower mass gap. We also examine the statistical significance of the similarity between the heavier component masses of GW190814 and GW200210_092254, and find that a model in which the mass of GW200210_092254 is drawn from the mass posterior of GW190814 is preferred ($\mathcal{B}\sim 18$) to a model in which its mass is drawn from the overall mass distribution of black holes detected in gravitational wave events. This hints at a common origin of the primary masses, as well as the secondary masses, in GW190814 and GW200210_092254.

We report the first laboratory and interstellar detection of the alpha-cyano vinyl radical (H2CCCN). This species was produced in the laboratory by an electric discharge of a gas mixture of vinyl cyanide, CH2CHCN, and Ne, and its rotational spectrum was characterized using a Balle-Flygare narrowband-type Fourier-transform microwave spectrometer operating in the frequency region of 8-40 GHz. The observed spectrum shows a complex structure due to tunneling splittings between two torsional sublevels of the ground vibronic state, 0+ and 0-, derived from a large-amplitude inversion motion. In addition, the presence of two equivalent hydrogen nuclei makes necessary to discern between ortho- and para-H2CCCN. A least squares analysis reproduces the observed transition frequencies with a standard deviation of ca. 3 kHz. Using the laboratory predictions, this radical is detected in the cold dark cloud TMC-1 using the Yebes 40m telescope and the QUIJOTE line survey. The 404-303 and 505-404 rotational transitions, composed of several hyperfine components, were observed in the 31.0-50.4 GHz range. Adopting a rotational temperature of 6K we derive a column density of (1.4+/-0.2)e11 cm-2 and (1.1+/-0.2)e11 cm-2 for ortho-H2CCCN and para-H2CCCN, respectively. The reactions C + CH3CN, and perhaps also N + CH2CCH, emerge as the most likely routes to H2CCCN in TMC-1.

Recently, hybrid bias expansions have emerged as a powerful approach to modelling the way in which galaxies are distributed in the Universe. Similarly, field-level emulators have recently become possible thanks to advances in machine learning and $N$-body simulations. In this paper we explore whether both techniques can be combined to provide a field-level model for the clustering of galaxies in real and redshift space. Specifically, here we will demonstrate that field-level emulators are able to accurately predict all the operators of a $2^{\rm nd}$-order hybrid bias expansion. The precision achieved in real and redshift space is similar to that obtained for the nonlinear matter power spectrum. This translates to roughly 1-2\% precision for the power spectrum of a BOSS and a Euclid-like galaxy sample up to $k\sim 0.6 h^{-1}$Mpc. Remarkably, this combined approach also delivers precise predictions for field-level galaxy statistics. Despite all these promising results, we detect several areas where further improvements are required. Therefore, this work serves as a road-map for the developments required for a more complete exploitation of upcoming large-scale structure surveys.

The relation between the resolved star formation rate per unit area and the non-thermal radio continuum emission is studied in 21 Virgo cluster galaxies and the two nearby spiral galaxies, NGC6946 and M51. For the interpretation and understanding of our results we used a 3D model where star formation, 2D cosmic ray (CR) propagation, and the physics of synchrotron emission are included. Based on the linear correlation between the star formation rate per unit area and the synchrotron emission and its scatter radio-bright and radio-dim regions can be robustly defined for our sample of spiral galaxies. We identified CR diffusion or streaming as the physical causes of radio-bright regions of unperturbed symmetric spiral galaxies as NGC6946. We identified the probable causes of radio-bright regions in several galaxies as CR transport, via either gravitational tides (M51) or galactic winds (NGC4532) or ram pressure stripping (NGC4330 and NGC4522). Three galaxies are overall radio-dim: NGC4298, NGC4535, and NGC4567. Based on our model of synchrotron-emitting disks we suggest that the overall radio-dim galaxies have a significantly lower magnetic field than expected by equipartition between the magnetic and turbulent energy densities. Radio-bright regions frequently coincide with asymmetric ridges of polarized radio continuum emission, and we found a clear albeit moderate correlation between the polarized radio continuum emission and the radio/SFR ratio. When compression or shear motions of the interstellar medium (ISM) are present in the galactic disk, the radio-bright regions are linked to the commonly observed asymmetric ridges of polarized radio continuum emission and represent a useful tool for the interaction diagnostics. Based on our results, we propose a scenario for the interplay between star formation, CR electrons, and magnetic fields in spiral galaxies.

The origin of the TeV--PeV astrophysical neutrinos seen by the IceCube telescope is unknown. If they are made in proton-photon interactions in astrophysical sources, their spectrum may show bump-like features. We search for such features in the 7.5-years High-Energy Starting Events (HESE), and forecast the power of such searches using larger data samples expected from upcoming telescopes. Present-day data reveals no evidence of bump-like features, which allows us to constrain candidate populations of photohadronic neutrino sources. Near-future forecasts show promising potential for stringent constraints or decisive discovery of bump-like features. Our results provide new insight into the origins of high-energy astrophysical neutrinos, complementing those from point-source searches.

Two recently discovered white dwarfs, WDJ041246.84$+$754942.26 and WDJ165335.21$-$100116.33, exhibit H$\alpha$ and H$\beta$ Balmer line emission similar to stars in the emerging DAHe class, yet intriguingly have not been found to have detectable magnetic fields. These white dwarfs are assigned the spectral type DAe. We present detailed follow-up of the two known DAe stars using new time-domain spectroscopic observations and analysis of the latest photometric time-series data from TESS and ZTF. We measure the upper magnetic field strength limit of both stars as $B < 0.05$ MG. The DAe white dwarfs exhibit photometric and spectroscopic variability, where in the case of WDJ041246.84$+$754942.26 the strength of the H$\alpha$ and H$\beta$ emission cores varies in anti-phase with its photometric variability over the spin period, which is the same phase relationship seen in DAHe stars. The DAe white dwarfs closely cluster in one region of the Gaia Hertzsprung-Russell diagram together with the DAHe stars. We discuss current theories on non-magnetic and magnetic mechanisms which could explain the characteristics observed in DAe white dwarfs, but additional data are required to unambiguously determine the origin of these stars.

IW Per, a single-lined spectroscopic binary with a short period of 0.92d, is known to be a A-type metallic-line (Am) star showing anomalous line strengths of specific elements. Previously, Kim (1980) reported that its equivalent widths of CaII 3934, SrII 4215, and ScII 4320 lines (important key lines characterizing the Am anomaly) show cyclic variations in accordance with the rotation phase, implyig that the chemical peculiarities on the surface are not uniform but of rather patchy distribution, though no trial of reconfirmation seems to have been done so far. In order to check the validity of this finding, 10 high-dispesion spectra of IW Per covering different phases were analyzed for these lines by using the spectrum-fitting technique to determine the abundances of Ca, Sr, and Sc and the corresponding equivalent widths. It turned out, however, that no firm evidence of such phase-dependent line-strength variations could be found, suggesting that significant chemical inhomogeneity on the surface of IW Per is unlikely to exist, at least as regards to the period of our observations (2010 December). Meanwhile, the abundances of O, Si, Ca, Ba, and Fe resulting from the 6130-6180A region corroborate that IW Per is a distinct Am star despite that its rotational velocity (~100 km/s) is near to the existent limit of Am phenomenon.

Joint observations in electromagnetic and gravitational waves shed light on the physics of objects and surrounding environments with extreme gravity that are otherwise unreachable via siloed observations in each messenger. However, such detections remain challenging due to the rapid and faint nature of counterparts. Protocols for discovery and inference still rely on human experts manually inspecting survey alert streams and intuiting optimal usage of limited follow-up resources. Strategizing an optimal follow-up program requires adaptive sequential decision-making given evolving light curve data that (i) maximizes a global objective despite incomplete information and (ii) is robust to stochasticity introduced by detectors/observing conditions. Reinforcement learning (RL) approaches allow agents to implicitly learn the physics/detector dynamics and the behavior policy that maximize a designated objective through experience. To demonstrate the utility of such an approach for the kilonova follow-up problem, we train a toy RL agent for the goal of maximizing follow-up photometry for the true kilonova among several contaminant transient light curves. In a simulated environment where the agent learns online, it achieves 3x higher accuracy compared to a random strategy. However, it is surpassed by human agents by up to a factor of 2. This is likely because our hypothesis function (Q that is linear in state-action features) is an insufficient representation of the optimal behavior policy. More complex agents could perform at par or surpass human experts. Agents like these could pave the way for machine-directed software infrastructure to efficiently respond to next generation detectors, for conducting science inference and optimally planning expensive follow-up observations, scalably and with demonstrable performance guarantees.

During a systematic search for new X-ray pulsators in the XMM-Newton archive, we discovered a high amplitude ($PF\simeq86\%$) periodic ($P\simeq7.25\,\mathrm{s}$) modulation in the X-ray flux of 4XMM J045626.3-694723 (J0456 hereafter), a previously unclassified source in the Large Magellanic Cloud (LMC). The period of the modulation is strongly suggestive of a spinning neutron star (NS). The source was detected only during one out of six observations in 2018-2022. Based on an absorbed power-law spectral model with photon slope of $\Gamma\simeq 1.9$, we derive a 0.3-10 keV luminosity of $L_\mathrm{X}\simeq2.7\times10^{34}$ erg cm$^{-2}$ s$^{-1}$ for a distance of 50 kpc. The X-ray properties of J0456 are at variance with those of variable LMC X-ray pulsars hosted in high-mass X-ray binary systems with a Be-star companion. Based on SALT spectroscopic observations of the only optical object that matches the X-ray uncertainty region, we cannot completely rule out that J0456 is a NS accreting from a late-type (G8-K3) star, an as-yet-unobserved binary evolutionary outcome in the MCs. We show that the source properties are in better agreement with those of magnetars. J0456 may thus be second known magnetar in the LMC after SGR 0526-66.

We present a forecast analysis on the feasibility of measuring the cosmological parameters with a large number of galaxy-galaxy scale strong gravitational lensing systems. Future wide area surveys are expected to discover and measure the properties of more than 10 000 strong lensing systems. We develop a hierarchical model that can simultaneously constrain the lens population and cosmological parameters by combining Einstein radius measurements with stellar dynamical mass estimates for every lens. Marginalizing over the lens density profiles and stellar orbital anisotropies, we find that $w$ can be constrained to a precision of $0.11$ with 10 000 galaxy-galaxy lens systems, which would be better than any existing single-probe constraint. We test our method on 161 existing lenses, finding $w=-0.96\pm0.46$. We also show how to mitigate against the potential systematic of redshift evolution in the mean lens density profile of the population.

We present high-resolution VLT/UVES spectroscopy and a detailed analysis of the unique Broad Absorption-Line system towards the quasar SDSS J165252.67+265001.96. This system exhibits low-ionization metal absorption lines from the ground states and excited energy levels of Fe II and Mn II, and the meta-stable 2^3S excited state of He I. The extended kinematics of the absorber encompasses three main clumps with velocity offsets of -5680, -4550, and -1770 km s$^{-1}$ from the quasar emission redshift, $z=0.3509\pm0.0003$, derived from [O II] emission. Each clump shows moderate partial covering of the background continuum source, $C_f \approx [0.53; 0.24; 0.81]$. We discuss the excitation mechanisms at play in the gas, which we use to constrain the distance of the clouds from the Active Galactic Nucleus (AGN) as well as the density, temperature, and typical sizes of the clouds. The number density is found to be $n_{\rm H} \sim 10^4\rm cm^{-3}$ and the temperature $T_e \sim 10^4\rm\,K$, with longitudinal cloudlet sizes of $\gtrsim0.01$ pc. Cloudy photo-ionization modelling of He I$^{*}$, which is also produced at the interface between the neutral and ionized phases, assuming the number densities derived from Fe II, constrains the ionization parameter to be $\log U \sim -3$. This corresponds to distances of a few 100 pc from the AGN. We discuss these results in the more general context of associated absorption-line systems and propose a connection between FeLoBALs and the recently-identified molecular-rich intrinsic absorbers. Studies of significant samples of FeLoBALs, even though rare per se, will soon be possible thanks to large dedicated surveys paired with high-resolution spectroscopic follow-ups.

MIRI/MRS on board the JWST allows us to probe the inner regions of protoplanetary disks. Here we examine the disk around the classical T Tauri star Sz 98, which has an unusually large dust disk in the millimetre with a compact core. We focus on the H$_2$O emission through both its ro-vibrational and pure rotational emission. Furthermore, we compare our chemical findings with those obtained for the outer disk from Atacama Large Millimeter/submillimeter Array (ALMA) observations. In order to model the molecular features in the spectrum, the continuum was subtracted and LTE slab models were fitted. The spectrum was divided into different wavelength regions corresponding to H$_2$O lines of different excitation conditions, and the slab model fits were performed individually per region. We confidently detect CO, H$_2$O, OH, CO$_2$, and HCN in the emitting layers. The isotopologue H$^{18}_2$O is not detected. Additionally, no other organics, including C$_2$H$_2$, are detected. This indicates that the C/O ratio could be substantially below unity, in contrast with the outer disk. The H$_2$O emission traces a large radial disk surface region, as evidenced by the gradually changing excitation temperatures and emitting radii. The OH and CO$_2$ emission are relatively weak. It is likely that H$_2$O is not significantly photodissociated; either due to self-shielding against the stellar irradiation, or UV-shielding from small dust particles. The relative emitting strength of the different identified molecular features point towards UV-shielding of H$_2$O in the inner disk of Sz 98, with a thin layer of OH on top. The majority of the organic molecules are either hidden below the dust continuum, or not present. In general, the inferred composition points to a sub-solar C/O ratio (<0.5) in the inner disk, in contrast with the larger than unity C/O ratio in the gas in the outer disk found with ALMA.

We study simultaneous soft ($0.7 - 7$ keV) and hard ($7 - 20$ keV) X-ray light curves at a total of eight epochs during $2016 - 2019$ of two TeV blazars Mrk 421 and 1ES 1959+650 observed by the SXT and LAXPC instruments onboard AstroSat. The light curves are $45 - 450$ ks long and may be sampled with time bins as short as $600 - 800$ sec with high signal to noise ratio. The blazars show a harder when brighter trend at all epochs. Discrete cross-correlation functions indicate that the hard and soft X-ray variability are strongly correlated. The time lag is consistent with zero in some epochs, and indicates hard or soft lag of a few hours in the rest. In the leptonic model of blazar emission, soft lag may be due to slower radiative cooling of lower energy electrons while hard lag may be caused by gradual acceleration of the high energy electrons emitting at the hard X-ray band. Assuming the above scenario and the value of the Doppler factor ($\delta$) to be $10 - 20$, the hard and soft lags may be used to estimate the magnetic field to be $\sim 0.1$ Gauss and the acceleration parameter to be $\sim 10^4$ in the emission region. Due to the availability of the high time resolution ($\sim$ minutes to hours) light curves from AstroSat, the value of the illusive acceleration parameter could be estimated, which provides a stringent constraint on the theories of particle acceleration in blazar jets.

In the primordial plasma, at temperatures above the scale of electroweak symmetry breaking, the presence of chiral asymmetries is expected to induce the development of helical hypermagnetic fields through the phenomenon of chiral plasma instability. It results in magnetohydrodynamic turbulence due to the high conductivity and low viscosity and sources gravitational waves that survive in the universe today as a stochastic polarized gravitational wave background. In this article, we show that this scenario only relies on Standard Model physics, and therefore the observable signatures, namely the relic magnetic field and gravitational background, are linked to a single parameter controlling the initial chiral asymmetry. We estimate the magnetic field and gravitational wave spectra, and validate these estimates with 3D numerical simulations.

Radio observations allow us to identify a wide range of active galactic nuclei (AGN), which are galaxies that have gas accreting onto the supermassive black-hole at the centre. By observing these sources at multiple radio frequencies, a more-complete picture can be built of black-hole accretion activity. This completeness is aided by radio waves being unaffected by dust along the line-of-sight to these sources, which cannot be said for waves in the optical part of the electromagnetic spectrum. (Hence, dust obscuration leads to biases in AGN samples selected using optical observations.) A thorough compilation of ~2,000 of the brightest radio-sources in the southern sky [and so of particular relevance for the Square Kilometre Array (SKA) and its precursor/pathfinder telescopes] is the GLEAM 4-Jy (G4Jy) Sample, selected at 151 MHz, with subsets being followed up with MeerKAT and the Australia Telescope Compact Array (ATCA). Meanwhile, optical spectroscopy from the Southern African Large Telescope (SALT) is being used to derive crucial redshift information, both for G4Jy sources and for radio-faint AGN in the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Survey. The origin of the radio emission in these faint sources is a subject of great debate within the AGN/radio-astronomy communities.

The lowest-order force balance in rotating stars is between gravity, pressure, and the centrifugal force (here referred to as 'GPR' balance). GPR balance determines both the stellar oblateness and the aspherical thermal anomalies. Here we emphasize a subtle point. Stellar thermal wind balance is simply the curl of GPR balance and the stellar thermal wind should be regarded as the baroclinic component of the oblateness. The thermal wind thus determines only part of the aspherical thermal anomalies, which have both baroclinic and barotropic contributions. Here we treat the full oblateness, including the thermal wind, using pressure coordinates. We derive the generalised stellar thermal wind equation and identify the parameter regime for which it holds. In the case of the Sun, not including the oblateness has resulted in conflicting calculations of the theoretical aspherical temperature anomaly. We provide new calculation here and find that the baroclinic anomaly from the thermal wind is ~3-60 times smaller than the barotropic anomaly and may not be measurable helioseismically. If measurement were possible, this would potentially yield a new way to bracket the depth of the solar tachocline.

The intracluster medium (ICM) is the low-density diffuse magnetized plasma in galaxy clusters, which reaches virial temperatures of up to 10^8 K. Under these conditions, the plasma is weakly collisional and therefore has an anisotropic pressure tensor with respect to the local direction of the magnetic field. This triggers very fast, Larmor-scale, pressure-anisotropy-driven kinetic instabilities that alter magnetic field amplification. We study magnetic field amplification through a turbulent small-scale dynamo, including the effects of the kinetic instabilities, during the evolution of a typical massive galaxy cluster. A specific aim of this work is to establish a redshift limit from which a dynamo has to start to amplify the magnetic field up to equipartition with the turbulent velocity field at redshift z=0. We implemented 1D radial profiles for various plasma quantities for merger trees generated with the Modified GALFORM algorithm. We assume that turbulence is driven by successive mergers of dark matter halos and construct effective models for the Reynolds number Re_eff dependence on the magnetic field in three different magnetization regimes, including the effects of kinetic instabilities. The magnetic field growth rate is calculated for the different Re_eff models. The model results in a higher magnetic field growth rate at higher redshift. For all scenarios considered, to reach equipartition at z=0, the amplification of the magnetic field has to start at redshift z_start=1.5 and above. The time to reach equipartition can be significantly shorter, in cases with systematically smaller turbulent forcing scales, and for the highest Re_eff models. Merger trees are useful tools for studying the evolution of magnetic fields in weakly collisional plasmas, and could also be used to constrain the different stages of the dynamo that potentially could be observed by future radio telescopes.

One of the major challenges for large-scale radio surface arrays, such as the Giant Radio Array for Neutrino Detection (GRAND), is the requirement of an autonomous online trigger for radio signals induced by extensive air showers. The NUTRIG project lays the foundations for the development of a pure, efficient, and scalable trigger in the context of GRAND. For this purpose, a GRAND prototype setup of four detection units has been deployed at Nan\c{c}ay, France, which currently serves as the main testing facility for the deployment of this autonomous trigger. This work provides a detailed description of the GRAND@Nan\c{c}ay setup, and a first analysis of background data gathered on site. Initial tests of signal recovery in laboratory conditions are also presented. Finally, near-future plans are outlined to scale NUTRIG to larger pathfinder arrays such as GRANDProto300.

The last few years have seen the development of a promising theoretical framework for statistics of the cosmic large-scale structure -- the theory of large deviations (LDT) for modelling weak-lensing one-point statistics in the mildly non-linear regime. The goal of this series of papers is to make the leap and lay out the steps to perform an actual data analysis with this theoretical tool. Building upon the LDT framework, in this work (Paper I) we demonstrate how to accurately model the Probability Distribution Function (PDF) of a reconstructed Kaiser-Squires convergence field under a realistic mask, that of the third data release of the Dark Energy Survey (DES). We also present how weak lensing systematics and higher-order lensing corrections due to intrinsic alignments, shear biases, photo-$z$ errors and baryonic feedback can be incorporated in the modelling of the reconstructed convergence PDF. In an upcoming work (Paper II) we will then demonstrate the robustness of our modelling through simulated likelihood analyses, the final step required before applying our method to actual data.

Accurately understanding the equation of state (EOS) of high-density, zero-temperature quark matter plays an essential role in constraining the behavior of dense strongly interacting matter inside the cores of neutron stars. In this Letter, we study the weak-coupling expansion of the EOS of cold quark matter and derive the complete, gauge-invariant contributions from the long-wavelength, dynamically screened gluonic sector at next-to-next-to-next-to-leading order (N3LO) in the strong coupling constant $\alpha_s$. This elevates the EOS result to the $O(\alpha_s^3 \ln \alpha_s)$ level, leaving only one unknown constant from the unscreened sector at N3LO, and places it on par with its high-temperature counterpart from 2003. This is achieved by generalizing next-to-leading order gluon self-energies within the hard-thermal-loop limit from high temperatures and densities to zero temperature. We find that including these screened gluonic contributions at N3LO yields a remarkably well-converged EOS, with essentially no renormalization-scale dependence. Finally, we perform a Bayesian estimation of the remaining unscreened contribution at N3LO and find that the full EOS of cold quark matter at this order may show markedly improved convergence over the lower-order results.

Invertible disformal transformations serve as a useful tool to explore ghost-free scalar-tensor theories. In this paper, we construct a generalization of invertible disformal transformations that involves arbitrary higher-order covariant derivatives of the scalar field. As a result, we obtain a more general class of ghost-free scalar-tensor theories than ever. Notably, our generalization is such that matter fields can be consistently coupled to these theories without introducing an unwanted extra degree of freedom in the unitary gauge.

To comprehensively understand saturation of two-dimensional ($2$D) magnetized Kelvin-Helmholtz-instability-driven turbulence, energy transfer analysis is extended from the traditional interaction between scales to include eigenmode interactions, by using the nonlinear couplings of linear eigenmodes of the ideal instability. While both kinetic and magnetic energies cascade to small scales, a significant fraction of turbulent energy deposited by unstable modes in the fluctuation spectrum is shown to be re-routed to the conjugate-stable modes at the instability scale. They remove energy from the forward cascade at its inception. The remaining cascading energy flux is shown to attenuate exponentially at a small scale, dictated by the large-scale stable modes. Guided by a widely used instability-saturation assumption, a general quasilinear model of instability is tested by retaining all nonlinear interactions except those that couple to the large-scale stable modes. These complex interactions are analytically removed from the magnetohydrodynamic equations using a novel technique. Observations are: an explosive large-scale vortex separation instead of the well-known merger of $2$D, a dramatic enhancement in turbulence level and spectral energy fluxes, and a reduced small-scale dissipation length-scale. These show critical role of the stable modes in instability saturation. Possible reduced-order turbulence models are proposed for fusion and astrophysical plasmas, based on eigenmode-expanded energy transfer analyses.

The Johannsen black hole (BH) is a generic rotating BH admitting three constants of motions ( energy, angular momentum and Carter constant) and is characterized by four deviation parameters besides mass and spin, which could be a model-independent probe of the no-hair theorem. We study the effects of the deviation parameters on the BH shadow as well as the effects of spin. By using the shadow boundaries of M87* and SgrA*, for the fist time, the deviation parameters of are constrained. The detail results depend on the spin $a$ and inclination angle $ \theta_0$. Assuming $a=0.2$ and $\theta_0=15^{\circ}$, the deviation parameter $\alpha_{13}$ are constained within $\sim $ [-3.5, 6] for M87* observation and [-3, 0.5] for SgrA* observation. We also show the images of a Johannsen BH surrounded by a Page-Thorne thin accretion disk observed by a remote observer with a ray-tracing method, and discuss the effects of the deviation parameters on deforming the accretion disk image, which could be tested by observations with higher sensitivities in the future.

Background: Precise understanding of nuclear fission is crucial for experimental and theoretical nuclear physics, astrophysics, and industrial applications; however, the complete physical mechanics is unresolved due to the complexities. Purpose: In this study, we present a new method to describe the dynamical-fission process and following prompt-neutron emission, where we combine the dynamical fission calculation based on the Langevin method and the Hauser-Feshbach statistical model. Methods: Two methods are connected smoothly within the universal charge distribution and the energy conservation, allowing us to calculate a sequence of fission dynamics and post-fission phase, including prompt neutron emission. Results: Using a certain set of model parameters, we successfully reproduce the experimental primary-fission yields, total kinetic energy, independent-fission yields, and prompt neutron emissions for the neutron induced fission of ${}^{236}$U, a compound nucleus of ${\rm n} + {}^{235}{\rm U}$. We elucidate the physical mechanism of the characteristic features observed in previous experiments, such as shell properties. Additionally, we apply our calculation to two very neutron-rich uranium isotopes, i.e., ${}^{250}$U and ${}^{255}$U, which are not experimentally confirmed but are important for r-process nucleosynthesis. Theoretical results indicate that ${}^{250}$U exhibits an asymmetric multiple-peak fission yield distribution, while the neutron-rich ${}^{255}$U has a single peak due to symmetric fission. Our method predicts post-neutron emission fragments, where ${}^{250}$U shows a stronger neutron emissivity than ${}^{255}$U. Conclusions: Our framework is highly reproducible in the experiments and shows that the number of emitted neutrons after fission differs significantly in neutron-rich uranium fission depending on distributions of fission variables.

In this paper, the implications of the symmetry energy on the hadron and quark phase transitions in the compact star, including the properties of the possible configurations of the quark-hadron hybrid stars, are investigated in the frameworks of the energy-density functional (EDF) models and the flavor SU(2) Nambu--Jona-Lasinio (NJL) model with the help of the Schwinger's covariant proper-time regularization (PTR) scheme. In this {theoretical setup}, the equations of states (EoSs) of hadronic matter for various values of symmetry energies obtained from the EDF models are employed to describe the hadronic matter, and the {flavor} SU(2) NJL model with various repulsive-vector interaction strengths are used to describe the quark matter. We then observe the obtained EoS in the mass-radius properties of the hybrid star configurations for various vector interactions and nuclear symmetry energies by solving the Tolman-Oppenheimer-Volkoff equation. We obtain that the critical density at which the phase transition occurs varies over the density (3.6--6.7)$\rho_0$ depending on the symmetry energy and the strength of the vector coupling $G_v$. The maximum mass of the neutron star (NS) is susceptible to $G_v$. When there is no repulsive force, the NS maximum mass is only about $1.5M_\odot$, but it becomes larger than $2.0M_\odot$ when the vector coupling constant is about half of the {attractive} scalar coupling constant. Surprisingly, the presence of the quark matter does not affect the canonical mass of NS ($1.4M_\odot$), so observing the canonical mass of NSs can provide unique constraints to the EoS of hadronic matter at high densities.

Ultralight bosonic fields (ULBFs) are predicted by various theories beyond the standard model of particle physics and are viable candidates of cold dark matter. There have been increasing interests to search for the ULBFs in physical and astronomical experiments. In this paper, we investigate the sensitivity of several planned space-based gravitational-wave interferometers to ultralight scalar and vector fields. Using time-delay interferometry (TDI) to suppress the overwhelming laser frequency noise, we derive the averaged transfer functions of different TDI combinations to scalar and vector fields, and estimate the impacts of bosonic field's velocities. We obtain the sensitivity curves for LISA, Taiji and TianQin, and explore their projected constraints on the couplings between ULBFs and standard model particles, illustrating with the ULBFs as dark matter.

It is shown that the required high quality of the Peccei-Quinn (PQ) symmetry can be a natural outcome of the multiple QCD axion models. In the axiverse, a hypothetical mass mixing between the QCD axions and axion-like particles (ALPs) can occur, which leads to an interesting phenomenon called the level crossing. In this paper, we investigate this mass mixing between one QCD axion and one ALP with the explicit PQ symmetry breaking in the early Universe. The dynamics of the axions and their cosmological evolutions when the level crossing occurs in this scenario are studied in detail. Then we focus our attention on the axion dark matter (DM) abundance. With several typical parameter sets for level crossing, we find that in the presence of the explicit PQ symmetry breaking term in the mixing, the total axion DM abundance is dominated by ALP and significantly suppressed.

Emission spectra of neodymium (Nd, Z=60) were recorded using Penning and hollow cathode discharge lamps in the region 11500-54000 cm$^{-1}$ (8695-1852 \r{A}) by Fourier transform spectroscopy at resolving powers up to 106. Wavenumber measurements were accurate to a few 10$^{-3}$ cm$^{-1}$. Grating spectroscopy of Nd vacuum sliding sparks and stellar spectra were used to aid line and energy level identification. The classification of 433 transitions of doubly-ionised neodymium (Nd III) from the Penning lamp spectra resulted in the determination of 144 energy levels of the 4f$^4$, 4f$^3$5d, 4f$^3$6s, and 4f$^3$6p configurations of Nd III, 105 of which were experimentally established for the first time. Of the 40 previously published Nd III levels, 1 was revised and 39 were confirmed. New Nd III atomic structure calculations were made using the Cowan code parameterised by newly established levels. These results will not only benchmark and improve future semi-empirical atomic structure calculations of Nd III, but also enable more reliable astrophysical applications of Nd III, such as abundance analyses of kilonovae and chemically peculiar stars, and studies of pulsational wave propagation in these stars.

Recently, a resonant state of four neutrons (tetraneutron) with an energy of $E_{4n}=2.37\pm 0.38 \rm{(stat)} \pm 0.44 \rm{(sys)}$ MeV and a width of $\Gamma=1.75\pm 0.22 \rm{(stat)} \pm 0.30 \rm{(sys)}$ MeV was reported. In this work, we analyse the effect of including such an exotic state on the yields of other light clusters, that not only form in astrophysical sites, such as core-collapse supernovae and neutron star mergers, but also in heavy-ion collisions. To this aim, we use a relativistic mean-field formalism, where we consider in-medium effects in a two-fold way, via the couplings of the clusters to the mesons, and via a binding energy shift, to compute the low-density equation of state for nuclear matter at finite temperature and fixed proton fraction. We consider five light clusters, deuterons, tritons, heliums, $\alpha$-particles, and $^6$He, immersed in a gas of protons and neutrons, and we calculate their abundances and chemical equilibrium constants with and without the tetraneutron. We also analyse how the associated energy of the tetraneutron would influence such results. We find that the low-temperature, neutron-rich systems, are the ones most affected by the presence of the tetraneutron, making neutron stars excellent environments for their formation. Moreover, its presence in strongly asymmetric matter may increase considerably the proton and the $\alpha$-particle fractions. This may have an influence on the dissolution of the accretion disk of the merger of two neutron stars.

Recent observations of high-energy neutrinos from active galactic nuclei (AGN), NGC 1068 and TXS 0506+056, suggest that cosmic rays (CRs) are accelerated in the vicinity of the central supermassive black hole and high-energy protons and electrons can cool efficiently via interactions with ambient photons and gas. The dark matter density may be significantly enhanced near the central black hole, and CRs could lose energies predominantly due to scatterings with the ambient dark matter particles. We propose CR cooling in AGN as a new probe of dark matter-proton and dark matter-electron scatterings. Under plausible astrophysical assumptions, our constraints on sub-GeV dark matter can be the strongest derived to date. Some of the parameter space favored by thermal light dark matter models might already be probed with current multimessenger observations of AGN.