Papers for Tuesday, Sep 13 2022

This proceeding contribution is a short summary of the invited talk about observational supernova science at Stockholm University that has been conducted at the Nordic Optical Telescope over the past 25 years, and some expectations for the future.

We present a method to characterize the noise in ground-based gravitational-wave observatories such as the Laser Gravitational-Wave Observatory (LIGO). This method uses linear regression algorithms such as the least absolute shrinkage and selection operator (LASSO) to identify noise sources and analyzes the detector output versus noise witness sensors to quantify the coupling of such noise. Our method can be implemented with currently available resources at LIGO, which avoids extra coding or direct experimentation at the LIGO sites. We present two examples to validate and estimate the coupling of elevated ground motion at frequencies below 10 Hz with noise in the detector output.

This white paper advocates the importance of multi-height measurements of the vector magnetic field in the solar atmosphere. As briefly described in this document, these measurements are critical for addressing some of the most fundamental questions in solar and heliospheric physics today, including: (1) What is the origin of the magnetic field observed in the solar atmosphere? (2) What is the coupling between magnetic fields and flows throughout the solar atmosphere? Accurate measurements of the photospheric and chromospheric three-dimensional magnetic fields are required for a precise determination of the emergence and evolution of active regions. Newly emerging magnetic flux in pre-existing magnetic regions causes an increase in the topological complexity of the magnetic field, which leads to flares and coronal mass ejections. Measurements of the vector magnetic field constitute also the primary product for space weather operations, research, and modeling of the solar atmosphere and heliosphere. The proposed next generation Ground-based solar Observing Network Group (ngGONG), a coordinated system of multi-platform instruments, will address these questions and provide large datasets for statistical investigations of solar feature behavior and evolution and continuity in monitoring for space-weather focused endeavors both research and operational. It will also enable sun-as-a-star investigations, crucial as we look toward understanding other planet-hosting stars.

We perform general relativistic simulations of self-gravitating black hole-disks in which the spin of the black hole is significantly tilted ($45^\circ$ and $90^\circ$) with respect to the angular momentum of the disk and the disk-to-black hole mass ratio is $16\%-28\%$. The black holes are rapidly spinning with dimensionless spins up to $\sim 0.97$. These are the first self-consistent hydrodynamic simulations of such systems, which can be prime sources for multimessenger astronomy. In particular tilted black hole-disk systems lead to: i) black hole precession; ii) disk precession and warping around the black hole; iii) earlier saturation of the Papaloizou-Pringle instability compared to aligned/antialigned systems, although with a shorter mode growth timescale; iv) acquisition of a small black-hole kick velocity; v) significant gravitational wave emission via various modes beyond, but as strong as, the typical $(2,2)$ mode; and vi) the possibility of a broad alignment of the angular momentum of the disk with the black hole spin. This alignment is not related to the Bardeen-Petterson effect and resembles a solid body rotation. Our simulations suggest that any electromagnetic luminosity from our models may power relativistic jets, such as those characterizing short gamma-ray bursts. Depending on the black hole-disk system scale the gravitational waves may be detected by LIGO/Virgo, LISA and/or other laser interferometers.

The distribution of gas in the circumgalactic medium (CGM) of galaxies of all types is poorly constrained. Foreground CGMs contribute an extra amount to the dispersion measure (DM) of fast radio bursts (FRB). We measure this DM excess for the CGMs of $10^{11}-10^{13}\ M_\odot$ halos using the CHIME/FRB first data release, a halo mass range that is challenging to probe in any other way. Because of the uncertainty in the FRBs' angular coordinates, only for nearby galaxies is the localization sufficient to confidently associate them with intersecting any foreground halo. Thus we stack on galaxies within 80 Mpc, optimizing the stacking scheme to approximately minimize the stack's variance and marginalize over uncertainties in FRB locations. The sample has 20-30 FRBs intersecting halos with masses of $10^{11}-10^{12}\ M_\odot$ and also of $10^{12}-10^{13}\ M_\odot$, and these intersections allow a marginal $1-2\,\sigma$ detection of the DM excess in both mass bins. The $10^{11}-10^{12}\ M_\odot$ halos bin also shows a DM excess at 1-2 virial radii. By comparing data with different models for the CGM gas profile, we find that all models are favored by the data up to 2-$\sigma$ level compared to the null hypothesis of no DM excess. With 2000-3000 more bursts from a future CHIME data release, we project a 4-$\sigma$ detection of the CGM. Distinguishing between viable CGM models by stacking FRBs with CHIME-like localization would require tens of thousands of bursts.

In the upcoming years, present and next-generation gravitational wave observatories will detect a larger number of Binary Neutron Star (BNS) mergers with increasing accuracy. In this context, improving BNS merger numerical simulations is crucial to correctly interpret the data and constrain the Equation of State (EOS) of Neutron Stars (NSs). State-of-the-art simulations of BNS mergers do not include muons. However, muons are known to be relevant in the microphysics of cold NSs and are expected to have a significant role in mergers, where the typical thermodynamics conditions favor their production. Our work aims at investigating the impact of muons on the merger remnant. We post-process the outcome of four numerical relativity simulations, performed with three different baryonic EOSs and two mass ratios, considering the first $15$ milliseconds after the merger. We compute the abundance of muons in the remnant and analyse how muons affect the trapped neutrino component and the fluid pressure. We find that the net fraction of muons is between $30 \%$ and $70 \%$ the one of electrons, depending on the baryonic EOS. Muons change the flavour hierarchy of trapped (anti)neutrinos, so that muon anti-neutrinos are the most abundant, followed by electron anti-neutrinos. Finally, muons modify the neutron to proton ratio inducing variations of the remnant pressure up to $7\%$. This work demonstrates that muons have a non-negligible effect on the outcome of BNS merger simulations, and they should be included to improve simulations accuracy.

Scientific articles published prior to the "age of digitization" in the late 1990s contain figures which are "trapped" within their scanned pages. While progress to extract figures and their captions has been made, there is currently no robust method for this process. We present a YOLO-based method for use on scanned pages, post-Optical Character Recognition (OCR), which uses both grayscale and OCR-features. When applied to the astrophysics literature holdings of the Astrophysics Data System (ADS), we find F1 scores of 90.9% (92.2%) for figures (figure captions) with the intersection-over-union (IOU) cut-off of 0.9 which is a significant improvement over other state-of-the-art methods.

We study the survival versus disruption of the giant clumps in high-redshift disc galaxies, short-lived (S) versus long-lived (L) clumps and two L sub-types, via analytic modeling tested against simulations. We develop a criterion for clump survival, with or without their gas, based on a predictive survivability parameter $S$. It compares the energy sources by supernova feedback and gravitational contraction to the clump binding energy and losses by outflows and turbulence dissipation. The clump properties are derived from Toomre instability, approaching virial and Jeans equilibrium, and the supernova energy deposit is based on an up-to-date bubble analysis. For moderate feedback levels, we find that L clumps exist with circular velocities $\sim\!50\, km\, s^{-1}$ and masses $\geq\!10^8\, M_\odot$. They are likely in galaxies with circular velocities $\geq \!200\, km\, s^{-1}$, consistent at $z \sim 2$ with the favored stellar mass for discs, $\geq\!10^{9.3}\, M_\odot$. L clumps favor disc gas fractions $\geq\!0.3$, low-mass bulges and redshifts $z\!\sim\! 2$. The likelihood of L clumps is reduced if the feedback is more ejective, e.g., if the supernovae are optimally clustered, if radiative feedback is very strong, if the stellar initial mass function is top-heavy, or if the star-formation-rate efficiency is particularly high. A sub-type of L clumps (LS), which lose their gas in several free-fall times but retain bound stellar components, may be explained by a smaller contraction factor and stronger external gravitational effects, where clump mergers increase the SFR efficiency. The more massive L clumps (LL) retain most of their baryons for tens of free-fall times with a roughly constant star-formation rate.

The detonation of a thin ($\lesssim$0.03\,$\mathrm{M_\odot}$) helium shell (He-shell) atop a $\sim$$1\,\mathrm{M_\odot}$ white dwarf (WD) is a promising mechanism to explain normal Type Ia supernovae (SNe\,Ia), while thicker He-shells and less massive WDs may explain some recently observed peculiar SNe\,Ia. We present observations of SN\,2020jgb, a peculiar SN\,Ia discovered by the Zwicky Transient Facility (ZTF). Near maximum light, SN\,2020jgb is slightly subluminous (ZTF $g$-band absolute magnitude $M_g$ between $-18.2$ and $-18.7$\,mag depending on the amount of host galaxy extinction) and shows an unusually red color ($g_\mathrm{ZTF}-r_\mathrm{ZTF}$ between 0.4 and 0.2\,mag) due to strong line-blanketing blueward of $\sim$5000\,\AA. These properties resemble those of SN\,2018byg, a peculiar SN\,Ia consistent with a thick He-shell double detonation (DDet) SN. Using detailed radiative transfer models, we show that the optical spectroscopic and photometric evolution of SN\,2020jgb are broadly consistent with a $\sim$0.95\,$\mathrm{M_\odot}$ (C/O core + He-shell; up to $\sim$1.00\,$\mathrm{M_\odot}$ depending on the total host extinction) progenitor ignited by a thick ($\sim$0.13\,$\mathrm{M_\odot}$) He-shell. We detect a prominent absorption feature at $\sim$1\,\micron\ in the near-infrared (NIR) spectrum of SN\,2020jgb, which could originate from unburnt helium in the outermost ejecta. While the sample size is limited, similar 1\,\micron\ features have been detected in all the thick He-shell DDet candidates with NIR spectra obtained to date. SN\,2020jgb is also the first subluminous, thick He-shell DDet SN discovered in a star-forming galaxy, indisputably showing that He-shell DDet objects occur in both star-forming and passive galaxies, consistent with the normal SN\,Ia population.

The spin of intergalactic filaments has been predicted from simulations, and supported by tentative evidence from redshift-space filament shapes in a galaxy redshift survey: generally, a filament is redshifted on one side of its axis, and blueshifted on the other. Here, we investigate whether filament spins could have a measurable kinetic Sunyaev-Zel'dovich (kSZ) signal, from CMB photons scattering off of moving ionized gas; this pure velocity information is rather complementary to filament redshift-space shapes. We develop a technique to measure the kSZ dipole by combining galaxy redshift surveys with CMB experiments. We base our S/N analyses first on an existing filament catalogue, making simple assumptions about how ionised gas follows the galaxies and matter in each filament, and its combination with Planck data. We then investigate the detectability of the kSZ dipole using the combination of DESI or SKA-2 with next-stage CMB experiments. We find that the gas halos of filament galaxies co-rotating with filaments induce a stronger kSZ dipole signal than that from the diffuse filamentary gas, but both signals seem too small to detect in near-term surveys such as DESI+future CMB experiments. But the combination of SKA-2 with future CMB experiments could give a more than $10\sigma$ detection. The gain comes mainly from an increased area overlap and an increased number of filaments, but also the low noise and high resolution in future CMB experiments are important to capture signals from filaments small on the sky. Successful detection of the signals may help to find the gravitomagnetic effect in large-scale structure and advance our understanding on baryons in the cosmic web.

Sonification is the technique of representing data with sound, with potential applications in astronomy research for aiding discovery and accessibility. Several astronomy-focused sonification tools have been developed; however, efficacy testing is extremely limited. We performed testing of astronify, a prototype tool for sonification functionality within the Barbara A. Mikulski Archive for Space Telescopes (MAST). We created synthetic light curves containing zero, one, or two transit-like signals with a range of signal-to-noise ratios (SNRs=3-100) and applied the default mapping of brightness to pitch. We performed remote testing, asking participants to count signals when presented with light curves as a sonification, visual plot, or combination of both. We obtained 192 responses, of which 118 self-classified as experts in astronomy and data analysis. For high SNRs (=30 and 100), experts and non-experts performed well with sonified data (85-100% successful signal counting). At low SNRs (=3 and 5) both groups were consistent with guessing with sonifications. At medium SNRs (=7 and 10), experts performed no better than non-experts with sonifications but significantly better (factor of ~2-3) with visuals. We infer that sonification training, like that experienced by experts for visual data inspection, will be important if this sonification method is to be useful for moderate SNR signal detection within astronomical archives and broader research. Nonetheless, we show that even a very simple, and non-optimised, sonification approach allows users to identify high SNR signals. A more optimised approach, for which we present ideas, would likely yield higher success for lower SNR signals.

We present James Webb Space Telescope (JWST) imaging of NGC 7469 with the Near-Infrared Camera (NIRCam) and the Mid-InfraRed Instrument (MIRI). NGC 7469 is a nearby, $z=0.016317$, luminous infrared galaxy (LIRG) that hosts both a Seyfert Type-1.5 nucleus and a circumnuclear starburst ring with a radius of $\sim$0.5 kpc. The new near-infrared (NIR) JWST imaging reveals 65 star-forming regions, 36 of which were not detected by HST observations. Nineteen of the 36 sources have very red NIR colors that indicate obscurations up to A$_{\rm{v}}\sim7$ and a contribution of at least 25$\%$ from hot dust emission to the 4.4$\mu$m band. Their NIR colors are also consistent with young ($<$5 Myr) stellar populations and more than half of them are coincident with the MIR emission peaks. These younger, dusty star-forming regions account for $\sim$2$\%$ and $\sim$10$\%$ of the total 1.5$\mu$m and 4.4$\mu$m luminosity of the starburst ring, respectively. The addition of these young regions confirm the age bimodality seen in the star-forming regions of the ring. Moreover, we have increased the number of young sources by a factor of four, raising the total percentage of the young population to $\sim$40$\%$. These results illustrate the effectiveness of JWST in identifying and characterizing previously hidden star formation in the densest star-forming environments around AGN.

In this work we analyze the full linear behaviour of the constrained interacting dark energy (CIDER) model, which is a conformally coupled quintessence model tailored to mimic a $\Lambda$CDM expansion. We compute the matter and temperature anisotropies power spectra and test the model against recent observational data. We shed light on some particular subtleties of the background behaviour that were not fully captured in previous works, and study the physics of the linear cosmological observables. One novelty found was that matter perturbations are enhanced at large scales when compared with the ones of the standard $\Lambda$CDM. The reason and impact of this trend on the cosmological observables and on the physics of the early Universe are considered. We find that the introduction of the coupling parameter alleviates the $\sigma_8$ tension between early and late time probes although Planck data favours the $\Lambda$CDM limit of the model.

Turbulence is often invoked to explain the origin of nonthermal particles in space and astrophysical plasmas. By means of 3D fully kinetic particle-in-cell simulations, we demonstrate that turbulence in low-$\beta$ plasmas ($\beta$ is the ratio of plasma pressure to magnetic pressure) accelerates ions and electrons into a nonthermal energy distribution with a power-law energy range. The ion spectrum is harder than the electron one, and both distributions get steeper for higher $\beta$. We show that the energization of electrons is accompanied by a significant energy-dependent pitch-angle anisotropy, with most electrons moving parallel to the local magnetic field, while ions stay roughly isotropic. We demonstrate that particle injection from the thermal pool occurs in regions of high current density. Parallel electric fields associated with magnetic reconnection are responsible for the initial energy gain of electrons, whereas perpendicular electric fields control the overall energization of ions. Our findings have important implications for the origin of nonthermal particles in space and astrophysical plasmas.

In the recent years, global coronal models have experienced an ongoing increase in popularity as tools for forecasting solar weather. Within the domain of up to 21.5Rsun, magnetohydrodynamics (MHD) is used to resolve the coronal structure using magnetograms as inputs at the solar surface. Ideally, these computations would be repeated with every update of the solar magnetogram so that they could be used in the ESA Modelling and Data Analysis Working Group (MADAWG) magnetic connectivity tool (this http URL). Thus, it is crucial that these results are both accurate and efficient. While much work has been published showing the results of these models in comparison with observations, not many of it discusses the intricate numerical adjustments required to achieve these results. These range from details of boundary condition formulations to adjustments as large as enforcing parallelism between the magnetic field and velocity. By omitting the electric field in ideal-MHD, the description of the physics can be insufficient and may lead to excessive diffusion and incorrect profiles. We formulate inner boundary conditions which, along with other techniques, reduce artificial electric field generation. Moreover, we investigate how different outer boundary condition formulations and grid design affect the results and convergence, with special focus on the density and the radial component of the B-field. The significant improvement in accuracy of real magnetic map-driven simulations is illustrated for an example of the 2008 eclipse.

We present a 3D MHD simulation of two merging flux ropes exhibiting self-generated and self-sustaining turbulent reconnection (SGTR) that is fully 3D and fast. The exploration of SGTR is crucial for understanding the relationship between MHD turbulence and magnetic reconnection in astrophysical contexts including the solar corona. We investigate the pathway towards SGTR and apply novel tools to analyse the structure and topology of the reconnection layer. The simulation proceeds from 2.5D Sweet-Parker reconnection to 2.5D nonlinear tearing, followed by a dynamic transition to a final SGTR phase that is globally quasi-stationary. The transition phase is dominated by a kink instability of a large "cat-eye" flux rope and the proliferation of a broad stochastic layer. The reconnection layer has two general characteristic thickness scales which correlate with the reconnection rate and differ by a factor of approximately six: an inner scale corresponding with current and vorticity densities, turbulent fluctuations, and outflow jets, and an outer scale associated with field line stochasticity. The effective thickness of the reconnection layer is the inner scale of the effective reconnection electric field produced by turbulent fluctuations, not the stochastic thickness. The dynamics within the reconnection layer are closely linked with flux rope structures that are highly topologically complicated. Explorations of the flux rope structures and distinctive intermediate regions between the inner core and stochastic separatrices ("SGTR wings") are potentially key to understanding SGTR. The study concludes with a discussion on the apparent dualism between plasmoid-mediated and stochastic perspectives on SGTR.

Many compelling dark matter (DM) scenarios feature Coulomb-like interactions between DM particles and baryons, in which the cross section for elastic scattering scales with relative particle velocity as $v^{-4}$. Previous studies have invoked such interactions to produce heat exchange between cold DM and baryons and alter the temperature evolution of hydrogen. In this study, we present a comprehensive study of the effects of Coulomb-like scattering on structure formation, in addition to the known effects on the thermal history of hydrogen. We find that interactions which significantly alter the temperature of hydrogen at Cosmic Dawn also dramatically suppress the formation of galaxies that source the Lyman-$\alpha$ background, further affecting the global 21-cm signal. In particular, an interaction cross section at the current observational upper limit leads to a decrease in the abundance of star-forming halos by a factor of $\sim 2$ at $z\sim 20$, relative to cold, collisionless DM. We also find that DM that is 100% millicharged cannot reproduce the depth and the timing of the reported EDGES anomaly in any part of the parameter space. These results critically inform modeling of the global 21-cm signal and structure formation in cosmologies with DM-baryon scattering, with repercussions for future and upcoming cosmological data analysis.

We present maps of 4 galactic giant molecular clouds (GMCs) in the J=2-1 emission of both CO and $^{13}$CO. We use an LTE analysis to derive maps of the CO excitation temperature and column density and the distribution of total molecular gas column density, $\Sigma_{gas}$. The depletion of CO by freeze-out onto cold dust grains is accounted for by an approximation to the results of Lewis et al. (2021) which were derived from far-IR observations with {\it Herschel}. The surface density of young stellar objects (YSOs) is obtained from published catalogs. The mean YSO surface density exhibits a power-law dependence on $\Sigma_{gas}$, with exponents in the range 0.9 to 1.9. Gas column density probability distribution functions (PDFs) show power-law tails extending to high column densities. The distributions of sonic Mach number, $M_S$ are sharply peaked at $M_S \sim 5 - 8$ for 3 GMCs; a fourth has a broad distribution up to $M_S =30$, possibly a result of feedback effects from multiple OB stars. An analysis following the methodology of Pokhrel et al. (2021) finds that our sample of GMCs shows power-law relations that are somewhat shallower than found by Pokhrel et al. (2021) for the star formation rate vs. $<\Sigma_{gas}>$ and vs. $<\Sigma_{gas}>/t_{ff}$ in a different sample of clouds. We discuss possible differences in the two samples of star-forming clouds and the effects of stellar feedback on the relation between gas density and star formation rate.

We re-analyze the global orbital architecture and dynamical stability of the $\mu$ Arae planetary system. We have updated the best-fit elements and minimal masses of the planets based on literature radial velocity (RV) measurements, now spanning 15 years. This is twice the RVs interval used for the first characterization of the system in 2006. It consists of a Saturn- and two Jupiter-mass planets in low-eccentric orbits resembling the Earth-Mars-Jupiter configuration in the Solar system, as well as the close-in warm Neptune with a mass of ~14 Earth masses. Here, we constrain this early solution with the outermost period to be accurate to one month. The best-fit Newtonian model is characterized by moderate eccentricities of the most massive planets below 0.1 with small uncertainties ~0.02. It is close but meaningfully separated from the 2e:1b mean motion resonance of the Saturn-Jupiter-like pair, but may be close to weak three-body MMRs. The system appears rigorously stable over a wide region of parameter space covering uncertainties of several $\sigma$. The system stability is robust to a five-fold increase in the minimal masses, consistent with a wide range of inclinations, from 20 to 90 deg. This means that all planetary masses are safely below the brown dwarf mass limit. We found a weak statistical indication of the likely system inclination I~20-30 deg. Given the well constrained orbital solution, we also investigate the structure of hypothetical debris disks, which are analogs of the Main Belt and Kuiper Belt, and may naturally occur in this system.

We evaluate the performance of the Lyman-$\alpha$ forest weak gravitational lensing estimator of Metcalf et al. on forest data from hydrodynamic simulations and ray-traced simulated lensing potentials. We compare the results to those obtained from the Gaussian random field simulated Ly$\alpha$ forest data and lensing potentials used in previous work. We find that the estimator is able to reconstruct the lensing potentials from the more realistic data, and investigate dependence on spectrum signal to noise. The non-linearity and non-Gaussianity in this forest data arising from gravitational instability and hydrodynamics causes a reduction in signal to noise by a factor of $\sim2.7$ for noise free data and a factor of $\sim 1.5$ for spectra with signal to noise of order unity (comparable to current observational data). Compared to Gaussian field lensing potentials, using ray-traced potentials from N-body simulations incurs a further signal to noise reduction of a factor of $\sim1.3$ at all noise levels. The non-linearity in the forest data is also observed to increase bias in the reconstructed potentials by $5-25\%$, and the ray-traced lensing potential further increases the bias by $20-30\%$. We demonstrate methods for mitigating these issues including Gaussianization and bias correction which could be used in real observations.

We present a table of 215 SNRs with distances. %estimate New distances are found to SNR G$51.26+0.11$ of $6.6 \pm 1.7$ kpc using HI absorption spectra%Additionally, and to 5 other SNRs using maser/molecular cloud associations. We recalculate the distances and errors to all SNRs using a consistent rotation curve and provide errors where they were not previously estimated. This results in a significant distance revisions for 20 SNRs. Because of observational constraints and selection effects, there %seems to be is an apparent deficit of observed number of Galactic supernova remnants (SNRs). To investigate this, we employ two methods. The first method applies correction factors for the selection effects to derive the radial density distribution. The second method compares functional forms for the SNR surface density and selection function against the data to find which functions are consistent with the data. The total number of SNRs in the Galaxy is $\sim3500$ (Method 1) or in the range $\sim2400$ to $\sim5600$ (Method 2). We conclude that the current observed number of SNRs is not yet complete enough to give a well-determined total SNR number or radial density function.

On 2020 September 18 US Government sensors detected a bolide with peak bolometric magnitude of -19 over the western Pacific. The impact was also detected by the Geostationary Lightning Mapper (GLM) instrument on the GOES-17 satellite and infrasound sensors in Hawaii. The USG measurements reported a steep entry angle of $67{^{\circ}}$ from horizontal from a radiant $13{^{\circ}}$ E of N and an impact speed of 11.7 km/s. Interpretation of all energy yields produces a preferred energy estimate of 0.4 KT TNT, corresponding to a $23,000$ kilogram $3$ meter diameter meteoroid. A post-impact search of telescopic images found that the ATLAS survey captured the object just 10 minutes prior to impact at an Earth-centred distance of nearly $11,900$ kilometers with apparent magnitude $m\text{=}12.5$. The object appears as a $0.44{^{\circ}}$ streak originating on the eastern edge of the image extending one-third of the predicted (based on the CNEOS state vector) $1.26{^{\circ}}$ over the 30 second exposure. The streak shows brightness variability consistent with small asteroid rotation. The position of Earth's shadow, the object's size, and its consistency with the CNEOS state vector confirm the object is likely natural. This is the sixth exoatmospheric detection of an NEA impactor and the closest initial telescopic detection prior to an impact. The high altitude of peak fireball brightness suggest it was a weak object comparable in many respects with 2008 TC3 (Almahatta Sitta meteorite), with an absolute magnitude of $H=32.5$ and likely low albedo. Therefore we suggest the NEA as having been a C-complex asteroid.

With the aim of finding microlensing binaries containing brown-dwarf (BD) companions, we investigate the microlensing survey data collected during the 2016--2018 seasons. For this purpose, we first conducted modeling of lensing events with light curves exhibiting anomaly features that are likely to be produced by binary lenses. We then sorted out BD-companion binary-lens events by applying the criterion that the companion-to-primary mass ratio is $q \lesssim 0.1$. From this procedure, we identify 6 binaries with candidate BD companions, including OGLE-2016-BLG-0890L, MOA-2017-BLG-477L, OGLE-2017-BLG-0614L, KMT-2018-BLG-0357L, OGLE-2018-BLG-1489L, and OGLE-2018-BLG-0360L. We estimate the masses of the binary companions by conducting Bayesian analyses using the observables of the individual lensing events. According to the Bayesian estimation of the lens masses, the probabilities for the lens companions of the events OGLE-2016-BLG-0890, OGLE-2017-BLG-0614, OGLE-2018-BLG-1489, and OGLE-2018-BLG-0360 to be in the BD mass regime are very high with $P_{\rm BD}> 80\%$. For MOA-2017-BLG-477 and KMT-2018-BLG-0357, the probabilities are relatively low with $P_{\rm BD}=61\%$ and 69\%, respectively.

A rapid and relatively simple scheme of calculation is elaborated and applied to cosmological recombination of helium. Employing the nonrelativistic Coulomb Green's function, a wavefunction of a colliding electron is represented in an integral form applicable for calculations. Bound electrons of helium are described by the Hartree-Fock wavefunctions. The free-bound transition probabilities into excited states of helium, and the probabilities of bound-bound transitions in helium are calculated in different modes. It is revealed that free-bound transition probabilities weakly depend on to what extent a field experienced by a colliding electron deviates from the purely Coulomb field with charge Z=1, whereas these probabilities strongly depend on the choice of a wavefunction of a bound active electron involved in recombination.

KIC 6951642 has been reported as a candidate hybrid pulsator of type-$\gamma$ Doradus-$\delta$ Scuti from observations of the first quarters of the Kepler mission. We aim to investigate the pulsating nature of KIC 6951642 and to search for the signature of rotation and/or activity in the light curves. We performed an iterative frequency search of both Fourier spectra, and searched for regular patterns in them. We applied spectrum synthesis to determine the atmospheric stellar parameters. Since KIC 6951642 was reported to belong to a spectroscopic binary system, we fitted the time delays derived from the light curves with the radial velocities obtained from published as well as new spectra in an attempt to improve the quality of the first orbit. Follow-up spectroscopy showed that KIC 6951642 is a fast-rotating F0-type star in a possible single-lined binary with a period of $\sim$4.8 yr. In the low-frequency regime, we identified the frequencies of 0.721 d$^{-1}$ as well as of 0.0087 d$^{-1}$. We attribute the first frequency to stellar rotation and the second one to stellar activity with a cycle. We also detected $g$ modes, with the strongest mode located at 2.238 d$^{-1}$, as well as three asymmetric multiplets (with a mean spacing of 0.675$\pm$0.044 d$^{-1}$). In the high-frequency regime, we detected frequencies of type-$\delta$ Scuti, with the strongest mode located at 13.96 d$^{-1}$, as well as seven asymmetric multiplets (with a mean spacing of 0.665$\pm$0.084 d$^{-1}$). We subsequently identified a few more frequencies that appear to be combinations of a $g$ or $p$ mode and one of the higher cited frequencies not due to pulsations. We propose that KIC 6951642 accommodates for a fast-rotating $\gamma$ Dor-$\delta$ Sct hybrid star with various rotationally split multiplets of $g$ and $p$ modes and that it also displays a cycle lasting years of (possible) stellar activity.

We present CosmoGridV1: a large set of lightcone simulations for map-level cosmological inference with probes of large scale structure. It is designed for cosmological parameter measurement based on Stage-III photometric surveys with non-Gaussian statistics and machine learning. CosmoGridV1 spans the $w$CDM model by varying $\Omega_m$, $\sigma_8$, $w_0$, $H_0$, $n_s$, $\Omega_b$, and assumes three degenerate neutrinos with $\sum m_\nu$ = 0.06 eV. This space is covered by 2500 grid points on a Sobol sequence. At each grid point, we run 7 simulations with PkdGrav3 and store 69 particle maps at nside=2048 up to $z$=3.5, as well as halo catalog snapshots. The fiducial cosmology has 200 independent simulations, along with their stencil derivatives. An important part of CosmoGridV1 is the benchmark set of 28 simulations, which include larger boxes, higher particle counts, and higher redshift resolution of shells. They allow for testing if new types of analyses are sensitive to choices made in CosmoGridV1. We add baryon feedback effects on the map level, using shell-based baryon correction model. The shells are used to create maps of weak gravitational lensing, intrinsic alignment, and galaxy clustering, using the UFalcon code. The main part of CosmoGridV1 are the raw particle count shells that can be used to create full-sky maps for a given $n(z)$. We also release projected maps for a Stage-III forecast, as well as maps used previously in KiDS-1000 deep learning constraints with CosmoGridV1. The data is available at www.cosmogrid.ai.

The Alfv\'en wave (AW) is the most common fluctuation present within the emitted solar wind from the Sun. Moreover, the interaction between interplanetary coronal mass ejection (ICME) and high-speed stream (HSS) has been observed on several occasions. However, can such interaction generate an AW? What will be the nature of AW in such a scenario remains an open question. To answer it, we have investigated an ICME-HSS interaction event observed on 21st October 1999 at 1 AU by Wind spacecraft. We have used the Wal\'en test to identify AW and estimated Elsasser variables to find the characteristics of the AWs. We explicitly find that ICME were dominant with Sunward AWs, whereas the trailing HSS has strong anti-Sunward AW. We suggest that the ICME-HSS interaction deforms the MC of the ICME, resulting in the AWs inside the MC. In addition, the existence of reconnection within the ICME early stage can also be the leading cause of the origin of AW within it.

In this study we explore the possibility of simplifying the modeling of magnetohydrodynamic (MHD) slow body modes observed in photospheric magnetic structure such as the umbrae of sunspots and pores. The simplifying approach assumes that the variation of the eigenvalues of slow body waves can be derived by imposing that the longitudinal component of velocity with respect to the tube axis is zero at the boundary of the magnetic flux tube, which is in a good agreement with observations. To justify our approach we compare the results of our simplified model for slow body modes in cylindrical flux tubes with the model prediction obtained by imposing the continuity of the radial component of the velocity and total pressure at the boundary of the flux tube. Our results show that, to a high accuracy (less than 1\% for the considered model), the conditions of continuity of the component of transversal velocity and pressure at the boundary can be neglected when modelling slow body modes under photospheric conditions.

Machine learning models are nowadays ubiquitous in space missions, performing a wide variety of tasks ranging from the prediction of multivariate time series through the detection of specific patterns in the input data. Adopted models are usually deep neural networks or other complex machine learning algorithms providing predictions that are opaque, i.e., human users are not allowed to understand the rationale behind the provided predictions. Several techniques exist in the literature to combine the impressive predictive performance of opaque machine learning models with human-intelligible prediction explanations, as for instance the application of symbolic knowledge extraction procedures. In this paper are reported the results of different knowledge extractors applied to an ensemble predictor capable of reproducing cosmic-ray data gathered on board the LISA Pathfinder space mission. A discussion about the readability/fidelity trade-off of the extracted knowledge is also presented.

We discuss the bulk viscosity of hot and dense $npe\mu$ matter arising from weak-interaction direct Urca processes. We consider two regimes of interest: (a) the neutrino-transparent regime with $T\leq T_{\rm tr}$ ($T_{\rm tr}\simeq 5\div 10$ MeV is the neutrino-trapping temperature); and (b) the neutrino-trapped regime with $T\geq T_{\rm tr}$. Nuclear matter is modeled in relativistic density functional approach with density-dependent parametrization DDME2. The maximum of the bulk viscosity is achieved at temperatures $T \simeq 5\div 6$ MeV in the neutrino-transparent regime, then it drops rapidly at higher temperatures where neutrino-trapping occurs. As an astrophysical application, we estimate the damping timescales of density oscillations by the bulk viscosity in neutron star mergers and find that, e.g., at the oscillation frequency $f=10$ kHz, the damping will be very efficient at temperatures $4\leq T\leq 7$ MeV where the bulk viscosity might affect the evolution of the post-merger object.

Primordial Black Holes could be an important component of the dark matter in the Universe. If they exist, they would add a Poisson component to the matter power spectrum. The extra power would speed up the emergence of dark matter halos that seed the formation of first stars and galaxies. Kashlinsky (2021) suggested that the additional velocity fluctuations would accelerate the infall of baryons onto the dark matter potential wells. We analyze the effect of Primordial Black Holes on the baryon infall from recombination to reionization and find the correction to be a few percent of the power suppression first identified by Tseliakhovich \& Hirata (2010). However, the dynamical effect of this correction in addition to the extra power speeds up the formation of halos in the mass range of $10^4-10^{5-6}$M$_\odot$, while slightly decreasing the formation of those in the range $10^6-10^8$M$_\odot$ confirming earlier analytic estimates and recent results of numerical simulations.

The angular distance of the solar flares from their position to the projection point of the center of the Sun on the solar disk has been studied during the periods 1975${-}$2021 for GOES events and 2002${-}$2021 for RHESSI events. This distribution by the number of events of flare importance gives a specific curvature shape, that remains the same without significant changes, with the different GOES classifications, and with different observational satellites. during each solar cycle. The curvature of the distance distribution has four peaks, which are denoted by the four central rings around the center of the solar disk that look like the solar inner layers in the background. 1) The core circle [0 ${-}$ 15$^{\circ}$]: it is a projection of the solar core onto the solar disk. 2) Radiative ring [15$^{\circ}$ ${-}$ 45$^{\circ}$]. 3) The convection ring [45$^{\circ}$ ${-}$ 55$^{\circ}$ ]. The limb ring [80$^{\circ}$ ${-}$ 90$^{\circ}$]. A large number of solar flares occurred in the radiative and convection rings. While we have a few events in the core and limb rings.

Some repeating fast radio burst (FRB) sources show high burst rates, and the physical origin is still unknown. Outstandingly, the first repeater FRB 121102 appears extremely high burst rate with the maximum value reaching $122\,\mathrm{h^{-1}}$ or even higher. In this work, we propose that the high burst rate of an FRB repeater may be due to plate collisions in the crust of young neutron stars (NSs). In the crust of an NS, vortex lines are pinned to the lattice nuclei. When the relative angular velocity between the superfluid neutrons and the NS lattices is nonzero, a pinned force will act on the vortex lines, which will cause the lattice displacement and the strain on the NS crust growing. With the spin evolution, the crustal strain reaches a critical value, then the crust may crack into plates, and each of plates will collide with its adjacent ones. The Aflv\'en wave could be launched by the plate collisions and further produce FRBs. In this scenario, the predicted burst rate can reach $\sim 770\,\mathrm{h}^{-1}$ for an NS with the magnetic field of $10^{13}\,\rm{G}$ and the spin period of $0.01\,\rm{s}$. We further apply this model to FRB 121102, and predict the waiting time and energy distribution to be $P(t_{\mathrm{w}}) \propto t_{\text{w}}^{\alpha_{t_{\text{w}}}}$ with $\alpha_{t_{\text{w}}} \simeq -1.75$ and $N(E)\text{d}E \propto E^{\alpha_{E}}\text{d}E$ with $\alpha_{E} \simeq -1.67$, respectively. These properties are consistent with the observations of FRB 121102.

We have analyzed the parsec-scale linear polarization properties of 436 active galactic nuclei (AGN) based on 15~GHz polarimetric Very Long Baseline Array (VLBA) observations. We present polarization and total intensity images averaged over at least five epochs since 1996 January 19 through 2019 August 4. Stacking improves the image sensitivity down to $\sim$30 $\mu$Jy beam$^{-1}$ and effectively fills out the jet cross-section both in total intensity and linear polarization. It delineates the long-term persistent magnetic field configuration and its regularity by restoring spatial distributions of the electric vector position angle (EVPA) and fractional polarization, respectively. On average, about 10 years of stacking period is needed to reveal the stable and most-complete polarization distribution of a source. We find that the degree of polarization significantly increases down and across the jet towards its edges, typically manifesting U or W-shaped transverse profiles, suggesting a presence of a large-scale helical magnetic field associated with the outflow. In some AGN jets, mainly BL Lacs, we detect quasi-constant fractional polarization profiles across the jet, accompanied by EVPAs closely following the outflow. BL Lacs show higher fractional polarization values in their cores and jets than those in quasars up to hectoparsec de-projected scales, while on larger scales they become comparable. High-synchrotron-peaked BL Lac jets are found to be less polarized than intermediate and low-synchrotron-peaked BL Lacs. We confirm that the EVPAs in BL Lacs tend to align with the local jet direction, while quasars show an excess of orthogonal polarization orientation.

The recently discovered high energy emission from the recurrent nova RS Ophiuchi by Fermi-LAT ($>$ 100 MeV), H.E.S.S. and MAGIC ($>$ 100 GeV), hints towards a possible hadronic origin of this radiation component. From this high energy photon flux we derive the expected number of neutrino events that could be detected by present and future neutrino telescopes in the different energy ranges. We find the number to be well below the detectors' capabilities. Therefore, both hadronic and leptonic processes remain valid interpretations of this $\gamma$-ray emission. Preliminary estimates indicate that in order to detect a plausible number of neutrino events with {IceCube-DeepCore} and KM3NeT the novae distances should not be greater than $\sim 1$ and $\sim 2$ kpc, respectively. Current values of the rates of nova eruptions in the Milky Way will allow present and future neutrino facilities to detect neutrino events from novae on a time scale of the order of once or twice per decade.

The energetic feedback from supermassive black holes can influence star formation at the centres of galaxies. Observational evidence for AGN impact on star formation can be searched in galaxies by combining ultraviolet imaging and optical integral field unit data. The ultraviolet flux directly traces recent star formation, and the integral field unit data can reveal dust attenuation, gas ionisation mechanisms, and gas/stellar kinematics from the central regions of the galaxy disk. A pilot study on NGC 3982 shows star formation suppression in the central regions of the galaxy, likely due to negative AGN feedback, and enhanced star formation in the outer regions. The case of NGC 3982 could be observational evidence of AGN feedback operating in a Seyfert galaxy.

The Early Universe, together with many nearby dwarf galaxies, is deficient in heavy elements. The evolution of massive stars in such environments is thought to be affected by rotation. Extreme rotators amongst them tend to form decretion disks and manifest themselves as OBe stars. We use a combination of U B, GAIA, Spitzer, and Hubble Space Telescope photometry to identify the complete populations of massive OBe stars - one hundred to thousands in number - in five nearby dwarf galaxies. This allows us to derive the galaxy-wide fractions of main sequence stars that are OBe stars (f_OBe), and how it depends on absolute magnitude, mass, and metallicity (Z). We find f_OBe = 0.22 in the Large Magellanic Cloud (0.5 Z_Sun), increasing to f_OBe = 0.31 in the Small Magellanic Cloud (0.2 Z_Sun). In the so far unexplored metallicity regime below 0.2 Z_Sun, in Holmberg I, Holmberg II, and Sextans A, we also obtain high OBe star fractions of 0.27, 0.27, and 0.27, respectively. These high OBe star fractions, and the strong contribution in the stellar mass range which dominates the production of supernovae, shed new light on the formation channel of OBe stars, as well as on the preference of long-duration gamma-ray bursts and superluminous supernovae to occur in metal-poor galaxies.

The existence of scalar fields can be probed by observations of stochastic gravitational waves. Scalar fields mediate attractive forces, usually stronger than gravity, on the length scales shorter than their Compton wavelengths, which can be non-negligible in the early universe, when the horizon size is small. These attractive forces exhibit an instability similar to the gravitational instability, only stronger. They can, therefore, lead to the growth of structures in some species. We identify a gravitational waves signature of such processes and show that it can be detected by the future gravitational waves experiments.

The Hubble constant ($H_{0}$) is a measurement to describe the expansion rate of the Universe in the current era. However, there is a $4.4\sigma$ discrepancy between the measurements from the early Universe and the late Universe. In this research, we propose a model-free and distance-free method to constrain $H_{0}$. Combining Friedman-Lema\^itre-Robertson-Walker cosmology with geometrical relation of the proper motion of extragalactic jets, the lower limit ($H_{\rm 0,min}$) of $H_{0}$ can be determined using only three cosmology-free observables: the redshifts of the host galaxies, as well as the approaching and receding angular velocities of radio jets. Using these, we propose to use the Kolmogorov-Smirnov test (K-S test) between cumulative distribution functions of $H_{\rm 0,min}$ to differentiate cosmology. We simulate 100, 200, and 500 extragalactic jets with 3 levels of accuracy of the proper motion ($\mu_{a}$ and $\mu_{r}$), at $10\%$, $5\%$, and $1\%$, corresponding to the accuracies of the current and future radio interferometers. We perform K-S tests between the simulated samples as theoretical distributions with different $H_{0}$ and power-law index of velocity distribution of jets and mock observational data. Our result suggests increasing sample sizes leads to tighter constraints on both power-law index and the Hubble constant at moderate accuracy (i.e., $10\%$ and $5\%$) while at $1\%$ accuracy, increasing sample sizes leads to tighter constraints on power-law index more. Improving accuracy results in better constraints in the Hubble constant compared with the power-law index in all cases but it alleviates the degeneracy.

The dynamic evolution of coronal mass ejection (CME) in interplanetary space generates highly turbulent, compressed, and heated shock-sheath. This region furnishes a unique environment to study the turbulent fluctuations at the small scales and serve an opportunity for unfolding the physical mechanisms by which the turbulence is dissipated and plasma is heated. How does the turbulence in the magnetized plasma control the energy transport process in space and astrophysical plasmas is an attractive and challenging open problem of the 21st century. For this, the literature discusses three types of magnetohydrodynamics (MHD) waves/ fluctuations in magnetized plasma as the magnetosonic (fast), Alfv'enic (intermediate), and sonic (slow). The magnetosonic type is most common in the interplanetary medium. However, Alfv'enic waves/fluctuations have not been identified to date in the ICME sheath. The steepening of the Alfv'en wave can form a rotational discontinuity that leads to an Alfv'enic shock. But, the questions were raised on their existence based on the theoretical ground. Here, we demonstrate the observable in-situ evidence of Alfv'en waves inside turbulent shock-sheath at 1 AU using three different methods desciribed in the literature. We also estimate Els"asser variables, normalized cross helicity, normalized residual energy and which indicate outward flow of Alfv'en waves. Power spectrum analysis of IMF indicates the existence of Alfv'enic turbulence in ICME shock-sheath. The study has strong implications in the domain of interplanetary space plasma, its interaction with planetary plasma, and astrophysical plasma.

We present the discovery of a rare system detected in the TESS data showing three different eclipsing-like signals. TIC 452991707 and TIC 452991693 seem to be the second such system on the sky, whose two components separated about 16" are gravitationally bounded, or comprise a co-moving pair. The three periods detected from the TESS data are: PA=1.46155 d, PB=1.77418 d, and PC=1.03989 d, respectively. The A and B periods belong to TIC 452991707, while the C comes from the component TIC 452991693. The pair A shows the deepest eclipses, and its orbit is very slightly eccentric. The third period C has lowest amplitude (eclipsing or ellipsoidal nature), but originates from TIC 452991693, which is connected to A+B because both visual components share similar proper motion and distance. Long-term collection of data from older photometry from various surveys also shows that the two inner pairs A and B orbit around their barycenter. Its period is probably of a few years, but for a final derivation of its orbital parameters one needs more up-to-date data. Hence, we call for new observations of this amazing system.

We present a detailed analysis of a superflare on the active M dwarf star AD Leonis. The event presents a rare case of a stellar flare observed simultaneously in X-rays (with XMM-Newton) and in optical (with the Transiting Exoplanet Survey Satellite, TESS). The radiated energy both in the 0.2-12 keV X-ray band ($1.26 \pm 0.01 \cdot 10^{33}$ erg) and the bolometric value ($E_{F,bol} = 5.57 \pm 0.03 \cdot 10^{33}$ erg) put this event at the lower end of the superflare class. The exceptional photon statistics deriving from the proximity of AD Leo has enabled measurements in the 1-8 AA GOES band for the peak flux (X1445 class) and integrated energy ($E_{F,GOES} = 4.30 \pm 0.05 \cdot 10^{32}$ erg), making possible a direct comparison with data on flares from our Sun. From extrapolations of empirical relations for solar flares we estimate that a proton flux of at least $10^5\,{cm^{-2} s^{-1} sr^{-1}}$ accompanied the radiative output. With a time lag of 300s between the peak of the TESS white-light flare and the GOES band flare peak as well as a clear Neupert effect this event follows very closely the standard (solar) flare scenario. Time-resolved spectroscopy during the X-ray flare reveals, in addition to the time evolution of plasma temperature and emission measure, a temporary increase of electron density and elemental abundances, and a loop that extends in the corona by 13% of the stellar radius ($4 \cdot 10^9$ cm). Independent estimates of the footprint area of the flare from TESS and XMM-Newton data suggest a high temperature of the optical flare (25000 K), but we consider more likely that the optical and X-ray flare areas represent physically distinct regions in the atmosphere of AD Leo.

Solar filament oscillations have been known for decades. Now thanks to the new capabilities of the new telescopes, these periodic motions are routinely observed. Oscillations in filaments show key aspects of their structure. A systematic study of filament oscillations over the solar cycle can shed light on the evolution of the prominences. This work is a proof of concept that aims to automatically detect and parameterise such oscillations using H$\alpha$ data from the GONG network of telescopes. The proposed technique studies the periodic fluctuations of every pixel of the H$\alpha$ data cubes. Using the FFT we compute the power spectral density (PSD). We define a criterion to consider whether it is a real oscillation or whether it is a spurious fluctuation. This consists in considering that the peak in the PSD must be greater than several times the background noise with a confidence level of 95\%. The background noise is well fitted to a combination of red and white noise. We applied the method to several observations already reported in the literature to determine its reliability. We also applied the method to a test case, which is a data set in which the oscillations of the filaments were not known a priori. The method shows that there are areas in the filaments with PSD above the threshold value. The periodicities obtained are in general agreement with the values obtained by other methods. In the test case, the method detects oscillations in several filaments. We conclude that the proposed spectral technique is a powerful tool to automatically detect oscillations in prominences using H$\alpha$ data.

We draw the multimessenger picture of J1048+7143, a flat-spectrum radio quasar known to show quasi-periodic oscillations in the $\gamma$-ray regime. We generate the adaptively-binned Fermi Large Area Telescope light curve of this source above 168 MeV to find three major $\gamma$-ray flares of the source, such that all three flares consist of two-two sharp sub-flares. Based on radio interferometric imaging data taken with the Very Large Array, we find that the kpc-scale jet is directed towards west, while our analysis of $8.6$-GHz very long baseline interferometry data, mostly taken with the Very Long Baseline Array, revealed signatures of two pc-scale jets, one pointing towards east, one pointing towards south. We suggest that the misalignment of the kpc- and pc-scale jets is a revealing signature of jet precession. We also analyze the $5$-GHz total flux density curve of J1048+7143 taken with the Nanshan(Ur) and RATAN-600 single dish radio telescopes and find two complete radio flares, slightly lagging behind the $\gamma$-ray flares. We model the timing of $\gamma$-ray flares as signature of the spin-orbit precession in a supermassive black hole binary, and find that the binary could merge in the next $\sim 60-80$ years. We show that both the Pulsar Timing Arrays and the planned Laser Interferometer Space Antenna lack sensitivity and frequency coverage to detect the hypothetical supermassive black hole binary in J1048$+$7143. We argue that the identification of sources similar to J1048+7143 plays a key role to reveal periodic high-energy sources in the distant Universe.

Electron and positron fluxes in cosmic rays are currently measured with unprecedented precision by AMS-02 up to TeV energies, and represent unique probes for the local properties of our Galaxy. The interpretation of their spectra is at present still debated, especially for the excess of positrons above 10 GeV. The hypothesis that pulsars can significantly contribute to this excess has been consolidated after the observation of gamma-ray halos at TeV energies of a few degree size around Geminga and Monogem pulsars. However, the spatial and energetic Galactic distribution of pulsars and the details of the positron production, acceleration and release from these sources are not yet fully understood. I will describe how we can use the high-precision AMS-02 positron data to constrain the main properties of the Galactic pulsar population and of the positron acceleration needed to explain the observed fluxes. This is achieved by simulating a large number of Galactic pulsar populations, following the most recent self-consistent modelings for the pulsar spin-down and evolution properties, calibrated on catalog observations. By fitting the positron AMS-02 data together with a secondary component due to collisions of primary cosmic rays with the interstellar medium, we determine the physical parameters of the pulsars dominating the positron flux, and assess the impact of different assumptions on radial distributions, spin-down properties, Galactic propagation scenarios and positron emission time.

Novae are caused by runaway thermonuclear burning in the hydrogen-rich envelopes of accreting white dwarfs, which results in the envelope to expand rapidly and to eject most of its mass. For more than 30 years, nova theory has predicted the existence of a "fireball" phase following directly the runaway fusion, which should be observable as a short, bright, and soft X-ray flash before the nova becomes visible in the optical. Here we present the unequivocal detection of an extremely bright and very soft X-ray flash of the classical Galactic nova YZ Reticuli 11 hours prior to its 9 mag optical brightening. No X-ray source was detected 4 hours before and after the event, constraining the duration of the flash to shorter than 8 hours. In agreement with theoretical predictions, the source's spectral shape is consistent with a black body of $3.27^{+0.11}_{-0.33}\times 10^5$ K ($28.2^{+0.9}_{-2.8}$ eV), or a white dwarf atmosphere, radiating at the Eddington luminosity, with a photosphere that is only slightly larger than a typical white dwarf. This detection of the expanding white dwarf photosphere before the ejection of the envelope provides the last link of the predicted photospheric lightcurve evolution and opens a new window to measure the total nova energetics.

Operational flare forecasting aims at providing predictions that can be used to make decisions, typically at a daily scale, about the space weather impacts of flare occurrence. This study shows that video-based deep learning can be used for operational purposes when the training and validation sets used for the network optimization are generated while accounting for the periodicity of the solar cycle. Specifically, the paper describes an algorithm that can be applied to build up sets of active regions that are balanced according to the flare class rates associated to a specific cycle phase. These sets are used to train and validate a Long-term Recurrent Convolutional Network made of a combination of a convolutional neural network and a Long-Short Memory network. The reliability of this approach is assessed in the case of two prediction windows containing the solar storm of March 2015 and September 2017, respectively.

The observed deficit and excess of adjacent planet pairs with period ratios narrow and wide of 3:2 and 2:1, the nominal values for the corresponding mean motion resonances (MMRs), have intrigued many. Previously, using a suite of simulations, Chatterjee & Ford 2015 showed that the excess above the 2:1 MMR can be naturally explained if planet pairs, initially trapped in the 2:1 MMR, dynamically interact with nearby planetesimals in a disk. We build on this work by: a) updating the census of discovered planet pairs, b) extending the study to initially non-resonant as well as resonant planet pairs, c) using initial planet and orbital properties directly guided by those observed, and d) extending the initial period ratios to include both 2:1 and 3:2. We find that 1) interactions with planetesimals typically increase the period ratios of both initially resonant and non-resonant planet pairs; 2) starting from an initially flat distribution of systems across 3:2 and 2:1, these interactions can naturally create the deficits observed narrow of these period ratios; 3) contribution from initially resonant planet pairs is needed to explain the observed levels of excess wide of 3:2; 4) a mixture model where about 25% (1%) planet pairs were initially trapped into 3:2 (2:1) MMRs is favored to explain both the observed deficit and excess of systems across these period ratios, however, up to a few percent of planet pairs are expected to remain in MMR today.

Microwave Kinetic Inductance Detectors (MKIDs) are beginning to become more prominent in astronomical instrumentation, due to their sensitivity, low noise, high pixel count for superconducting detectors, and inherent energy and time resolving capability. The Kinetic Inductance Detector Spectrometer (KIDSpec) will take advantage of these features, KIDSpec is a medium resolution MKID spectrograph for the optical/near infrared. KIDSpec will contribute to many science areas particularly those involving short and/or faint observations. When short period binary systems are found, typical CCD detectors will struggle to characterise these systems due to the very short exposures required, causing errors as large as the estimated parameter itself. The KIDSpec Simulator (KSIM) has been developed to investigate how much KIDSpec could improve on this. KIDSpec was simulated on an ELT class telescope to find the extent of its potential, and it was found that KIDSpec could observe a $m_{V}\approx{24}$ with an SNR of 5 for a 10s exposure at 1420 spectral resolution. This would mean that KIDSpec on an ELT class telescope could spectroscopically follow up on any LSST photometric discoveries of LISA verification sources.

Flickering is a fast variability observed in all accreting systems. It has been shown that in most cataclysmic variables flickering originates in the accretion disc. However, in polars the strong magnetic field of the white dwarf prevents the formation of an accretion disc. Therefore, the origin of flickering in polars is not clear. We analyzed the changes of flickering amplitude with orbital phase in seven polars in order to reveal its site of origin. We show that at least in some polars there are two separate sources of flickering. Moreover, at least one of the sources is located at a large distance from the main source of light in the system.

By means of 3D hydrodynamic simulations, we explore the effects of rotation in the formation of second-generation (SG) stars in globular clusters (GC). Our simulations follow the SG formation in a first-generation (FG) internally rotating GC; SG stars form out of FG asymptotic giant branch (AGB) ejecta and external pristine gas accreted by the system. We have explored two different initial rotational velocity profiles for the FG cluster and two different inclinations of the rotational axis with respect to the direction of motion of the external infalling gas, whose density has also been varied. For a low (10^-24 g cm^-3) external gas density, a disk of SG helium-enhanced stars is formed. The SG is characterized by distinct chemo-dynamical phase space patterns: it shows a more rapid rotation than the FG with the helium-enhanced SG subsystem rotating more rapidly than the moderate helium-enhanced one. In models with high external gas density (10^-23 g cm^-3), the inner SG disc is disrupted by the early arrival of external gas and only a small fraction of highly enhanced helium stars preserves the rotation acquired at birth. Variations in the inclination angle between the rotation axis and the direction of the infalling gas and the velocity profile can slightly alter the extent of the stellar disc and the rotational amplitude. No significant variation has been found in the timespan of our simulations when changing the inclination angle between the rotation axis and the direction of the infalling gas, while different velocity profiles can slightly alter the extent of the stellar disc and the rotational amplitude. The results of our simulations illustrate the complex link between dynamical and chemical properties of multiple populations and provide new elements for the interpretation of observational studies and future investigations of the dynamics of multiple-population GCs.

We investigate the roles of stochastic grain heating in the formation of complex organic molecules (COMs) in cold cores, where COMs have been detected. Two different types of grain-size distributions are used in the chemical models. The first one is the MRN distribution, and the second one considers grain coagulation to study its effects on the chemical evolution in these environments. The macroscopic Monte Carlo method is used to perform the two-phase chemical model simulations. We find that (1) grain coagulation can affect certain gas-phase species, such as CO$_2$ and N$_2$H$^+$, in the cold core environments, which can be attributed to the volatile precursors originating from the small grains with temperature fluctuations; (2) grains with radii around 4.6 $\times$ 10$^{-3}$ $\mu$m contribute most to the production of COMs on dust grains under cold core conditions, while few species can be formed on even smaller grains with radii less than 2 $\times$ 10$^{-3}$ $\mu$m; (3) COMs formed on stochastically heated grains could help explain the observed abundances of gas-phase COMs in cold cores.

Spherical and aspherical models are presented for two outbursts in 2012 of supernova 2009ip. Models are based on a scenario which suggests that the August 2012 outburst is caused by the explosive shell ejection from LBV-presupernova. The model predicts an emergence of an unobserved outburst in late July 2012 related to a shock breakout and a subsequent diffusive radiative cooling of the ejected envelope. The luminosity of the first observed outburst in August 2012 was presumably powered by the central source, whereas the second, more powerful outburst in late September 2012, was caused by the ejecta interaction with the circumstellar envelope. Models provide estimates of the ejecta energy and mass along with the mass of the circumstellar shell.

The detection of habitable worlds is one of humanity's greatest endeavors. So far, astrobiological studies show that one of the most critical components for life development is liquid water. Its chemical properties and its capacity to dissolve and hence transport other substances makes this constituent a key piece in the development of life. As a consequence, looking for life as we know it is directly related to the search for liquid water. For a remote detection of life in distant planetary systems, this means looking for planets in the so-called habitable zone. In this sense, K-dwarf stars are the perfect hosts. Contrary to G-dwarfs, the habitable zone is closer, thus making planet detection easier using transit or radial velocity techniques. Contrary to M-dwarfs, the stellar activity is much smaller, hence having a smaller impact in both the detectability and in the true habitability of the planet. Also, K-dwarfs are the quietest in terms of oscillations, and granulation noise. Despite this, there is a dearth of planets in the habitable zone of K-dwarfs due to a lack of observing programs devoted to this parameter space. In response to a call for Legacy Programs of the Calar Alto observatory, we have started the first dedicated and systematic search for habitable planets around K-dwarfs, the K-dwarfs Orbited By habitable Exoplanets (KOBE). This survey is monitoring the radial velocity of 50 carefully pre-selected K-dwarfs with the CARMENES instrument along 5 semesters with an average of 90 data points per target. Based on planet occurrence rates convolved with our detectability limits, we expect to find $1.68\pm 0.25$ planets per star in the KOBE sample and in half of the sample we expect to find one of those planets within the habitable zone. In this paper, we describe the project motivation, goals and target selection and preliminary stellar characterization.

The molecule studied in this work, 2-hydroxyprop-2-enal, is among the candidates to be searched for in the interstellar medium (ISM), as it is a dehydration product of C3 sugars and contains structural motifs typical for some interstellar molecules. The aim of this work is to deepen knowledge about the millimetre-wave spectrum of 2-hydroxyprop-2-enal in the region enabling its search towards astronomical objects. We target the solar-type protostar IRAS16293-2422 and star-forming region Sagittarius (Sgr) B2(N). The rotational spectrum of 2-hydroxyprop-2-enal was measured and analysed in the frequency regions of 128-166 GHz and 285-329 GHz. The interstellar exploration towards IRAS16293-2422 was based on the Atacama Large Millimeter/submillimeter Array (ALMA) data of the Protostellar Interferometric Line Survey. We also used the imaging spectral line survey ReMoCA performed with ALMA toward Sgr B2(N). We modelled the astronomical spectra under the assumption of local thermodynamic equilibrium. We provide analysis of hundreds of rotational transitions of 2-hydroxyprop-2-enal in the ground state and the lowest lying excited vibrational state. We report its nondetection towards IRAS16293 B. The 2-hydroxyprop-2-enal/3-hydroxypropenal abundance ratio is estimated to be less-than or similar to 0.9-1.3 in agreement with the predicted value of 1.4. We also report the nondetection of 2-hydroxyprop-2-enal toward the hot molecular core Sgr B2(N1). We did not detect the related aldehydes 2-hydroxypropanal and 3-hydroxypropenal either. We find that these three molecules are at least 9, 4, and 10 times less abundant than acetaldehyde in this source, respectively. Despite the nondetections, the results of this work represent a significant improvement on previous investigations in the microwave region and meets the requirements for further searches of this molecule in the ISM.

The focus of this work is the current distribution of asteroids in co-orbital motion with Venus, Earth and Jupiter, under a quasi-coplanar configuration and for a medium-term timescale of the order of 900 years. A co-orbital trajectory is a heliocentric orbit trapped in a 1:1 mean-motion resonance with a given planet. As such, to model it this work considers the Restricted Three-Body Problem in the circular-planar case with the help of averaging techniques. The domain of each co-orbital regime, that is, the quasi-satellite motion, the horseshoe motion and the tadpole motion, can be neatly defined by means of an integrable model and a simple bi-dimensional map, that is invariant with respect to the mass parameter of the planet, and turns out to be a remarkable tool to investigate the distribution of the co-orbitals objects of interest. The study is based on the data corresponding to the ephemerides computed by the JPL Horizons system for asteroids with a sufficient low orbital inclination with respect to the Sun-planet orbital plane. These objects are cataloged according to their current dynamics, together with the transitions that occur in the given time frame from a given type of co-orbital motion to another. The results provide a general catalog of co-orbital asteroids in the solar system, the first one to our knowledge, and an efficient mean to study transitions.

After decades of speculation and searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance of cyanonaphthalene (CNN, C10H7CN) in the Taurus Molecular Cloud (TMC-1) is six orders of magnitude higher than expected from astrophysical modeling. Here, we report absolute unimolecular dissociation and radiative cooling rate coefficients of the 1-CNN isomer in its cationic form. These results are based on measurements of the time-dependent neutral product emission rate and Kinetic Energy Release distributions produced from an ensemble of internally excited 1-CNN + studied in an environment similar to that in interstellar clouds. We find that Recurrent Fluorescence - radiative relaxation via thermally populated electronic excited states - efficiently stabilizes 1-CNN+ , owing to a large enhancement of the electronic transition probability by vibronic coupling. Our results help explain the anomalous abundance of CNN in TMC-1 and challenge the widely accepted picture of rapid destruction of small PAHs in space.

Recent observations discovered that some repeating fast radio bursts (FRBs) show complex variations and reversals of Faraday rotation measures (RMs), indicating the sources of these FRBs are embedded in a dynamically magnetized environment. One possible scenario is that repeating FRBs generated by pulsars in binary systems, especially containing a high-mass companion with strong stellar outflows. Here, we study the RM variations caused by stellar winds, and a possible stellar disc. If the magnetic field is radial in the stellar wind, RM will reach the peak at periastron and will not reverse. For the toroidal magnetic field in the wind, RM will reverse at the super conjunction. The $\left| \mathrm{RM} \right|$ evolution is symmetric before and after the periastron for a radial magnetic field, or the super conjunction for a toroidal magnetic field. For the case of the toroidal field in the disc, the RM variations only occur at the time when the pulsar passes through the inclined disc before and after periastron. Our model can explain the secular RM variation of FRB 20180916B. Besides, the clumps in the stellar wind and disc can cause short time-scale ($< 1$ day) variations or reversals of RM. Therefore, long-term monitoring of RM variations can reveal the origins of FRBs.

The detection of GW170817 and the accompanying electromagnetic counterpart, AT2017gfo, have provided an important set of observational constraints for theoretical models of neutron star mergers, nucleosynthesis, and radiative transfer for kilonovae. We apply the 3D Monte Carlo radiative transfer code ARTIS to produce synthetic light curves of the dynamical ejecta from a neutron star merger, which has been modelled with 3D smooth-particle hydrodynamics (SPH) and included neutrino interactions. Nucleosynthesis calculations provide the energy released from radioactive decays of r-process nuclei, and radiation transport is performed using grey opacities given as functions of the electron fraction. We present line-of-sight dependent bolometric light curves, and find the emission along polar lines of sight to be up to a factor of ~2 brighter than along equatorial lines of sight. Instead of a distinct emission peak, our bolometric light curve exhibits a monotonic decline, characterised by a shoulder at the time when the bulk ejecta becomes optically thin. We show approximate band light curves based on radiation temperatures and compare these to the observations of AT2017gfo. We find that the rapidly declining temperatures lead to a blue to red colour evolution similar to that shown by AT2017gfo. We also investigate the impact of an additional, spherically symmetric secular ejecta component, and we find that the early light curve remains nearly unaffected, while after about 1 day the emission is strongly enhanced and dominated by the secular ejecta, leading to the shift of the shoulder from 1-2 to 6-10 days.

The study of the interstellar medium (ISM) in the X-rays has entered a golden age with the advent of the X-ray observatories XMM-Newton and Chandra. High-energy resolution allowed to study dust spectroscopic features with unprecedented detail. At the same time, the X-ray imaging capabilities offered a new perspective of dust scattering halos. Both spectroscopy and imaging rely on a simple geometry, where a distant X-ray source, usually a bright X-ray binary system, lies behind a multi-layered ISM. X-ray binaries can be found in different regions in the Galaxy, providing the unique chance to study the ISM in distinct environments. In the following we will describe how X-rays can be used as a tool to study gas and dust along the line of sight, revealing elemental abundances and depletion. The study of interstellar dust spectroscopic and imaging features can be used to extract the chemical and physical properties of the intervening dust, as well as its distribution along the line of sight.

This paper reports an environmental analysis of 41 uniformly-selected stripped-envelope supernovae (SESNe) based on deep ultraviolet-optical images acquired by the Hubble Space Telescope. Young stellar populations are detected in most SN environments and their ages are derived with a hierarchical Bayesian approach. The age distributions are indistinguishable between Type IIb and Type Ib while that for Type Ic is systematically younger. This suggests that the Type Ic SN progenitors are more massive while the Type IIb and Type Ib SNe have very similar progenitor masses. Our result supports a hybrid envelope-stripping mechanism, in which the hydrogen envelopes of the SESN progenitors are stripped via a mass-insensitive process (e.g. binary interaction) while the helium envelopes are stripped via a mass-sensitive process (e.g. stellar wind of the post-binary interaction progenitor). We also provide progenitor constraints for three Type Ibn SNe and two broad-lined Type Ic SNe. All these results demonstrate the importance of the very diverse mass-loss processes in the origins of SESNe.

SIGWfast is a python code to compute the scalar-induced gravitational wave spectrum from a primordial scalar power spectrum that can be given in analytical or numerical form. SIGWfast was written with the aim of being easy to install and use, and to produce results fast, typically in a matter of a few seconds. To this end the code employs vectorization techniques within python, but there is also the option to compile a C++ module to perform the relevant integrations, further accelerating the computation. The python-only version should run on all platforms that support python 3. The version employing the C++ module is only available for Linux and MacOS systems.

Observations of the phase curves and secondary eclipses of extrasolar planets provide a window on the composition and thermal structure of the planetary atmospheres. For example, the photometric observations of secondary eclipses lead to the measurement of the planetary geometric albedo $A_g$, which is an indicator of the presence of clouds in the atmosphere. In this work we aim to measure the $A_g$ in the optical domain of WASP-43b, a moderately irradiated giant planet with an equilibrium temperature of $\sim$1400~K. To this purpose, we analyze the secondary eclipse light curves collected by CHEOPS, together with TESS observations of the system and the publicly available photometry obtained with HST WFC3/UVIS. We also analyze the archival infrared observations of the eclipses and retrieve the thermal emission spectrum of the planet. By extrapolating the thermal spectrum to the optical bands, we correct the optical eclipses for thermal emission and derive the optical $A_g$. The fit of the optical data leads to a marginal detection of the phase curve signal, characterized by an amplitude of $160\pm60$~ppm and 80$^{+60}_{-50}$~ppm in the CHEOPS and TESS passband respectively, with an eastward phase shift of $\sim50^\circ$ (1.5$\sigma$ detection). The analysis of the infrared data suggests a non-inverted thermal profile and solar-like metallicity. The combination of optical and infrared analysis allows us to derive an upper limit for the optical albedo of $A_g<0.087$ with a confidence of 99.9\%. Our analysis of the atmosphere of WASP-43b places this planet in the sample of irradiated hot Jupiters, with monotonic temperature-pressure profile and no indication of condensation of reflective clouds on the planetary dayside.

We propose a new simple formalism to predict the orbital separations after common-envelope phases with massive star donors. We focus on the fact that massive red supergiants tend to have a sizeable radiative layer between the dense helium core and the convective envelope. Our formalism treats the common-envelope phase in two stages: dynamical in-spiral through the outer convective envelope and thermal timescale mass transfer from the radiative intershell. With fiducial choices of parameters, the new formalism typically predicts much wider separations compared to the classical energy formalism. Moreover, our formalism predicts that final separations strongly depend on the donor evolutionary stage and companion mass. Our formalism provides a physically-motivated alternative option for population synthesis studies to treat common-envelope evolution. This treatment will impact on predictions for massive-star binaries, including gravitational-wave sources, X-ray binaries and stripped-envelope supernovae.

The imprint of gravitational waves (GWs) on large-scale structures (LSS) is a useful and promising way to detect or to constrain them. Tensor fossils have been largely studied in the literature as an indirect way to detect primordial GWs. In this paper we analyze a new effect induced by primordial GWs: a correction to the density contrast of the underlying matter distribution of LSS, as well as its radiation counterpart, induced by the energy density fluctuation of the gravitational radiation. We perform our derivation of the full analytical solution of the density contrast for waves entering the horizon during radiation dominance. We account for two phases in the radiation era, depending on the main contributor to the perturbed energy density of the Universe. By comparing the density contrast of cold dark matter and radiation -- sourced by linear gravitational waves only -- we conclude that the former overcomes the latter at some time in the radiation era, a behaviour analogous to their linear counterpart. Then we conclude by discussing the case of density perturbations produced by GWs entering the Hubble radius during the matter era as well as their evolution in the late dark-energy dominated phase.

The meteorite sample Erg Chech (EC) 002 is the oldest felsic igneous rock from the Solar System analysed to date and provides a unique opportunity to study the formation of felsic crusts on differentiated protoplanets immediately after metal-silicate equilibration or core formation. The extinct 53Mn-53Cr chronometer provides chronological constraints on the formation of EC 002 by applying the isochron approach using chromite, metal-silicate-sulphide and whole-rock fractions as well as "leachates" obtained by sequential digestion of a bulk sample. Assuming a chondritic evolution of its parent body, a 53Cr/52Cr model age is also obtained from the chromite fraction. The 53Mn-53Cr isochron age of 1.73 (+/-) 0.96 Ma (anchored to D'Orbigny angirte) and the chromite model age constrained between 1.46 (-0.68/+0.78) and 2.18 (-1.06/+1.32) Ma after the formation of calcium-aluminium-rich inclusions (CAIs) agree with the 26Al-26Mg ages (anchored to CAIs) reported in previous studies. This indicates rapid cooling of EC 002 that allowed near-contemporaneous closure of multiple isotope systems. Additionally, excess in the neutron-rich 54Cr (nucleosynthetic anomalies) combined with mass-independent isotope variations of 17O provide genealogical constraints on the accretion region of the EC 002 parent body. The 54Cr and 17O isotope compositions of EC 002 confirm its origin in the "non-carbonaceous" reservoir and overlap with the vestoid material NWA 12217 and anomalous eucrite EET 92023. This indicates a common feeding zone during accretion in the protoplanetary disk between the source of EC 002 and vestoids. The enigmatic origin of iron meteorites remains still unresolved as EC 002, which is more like a differentiated crust, has an isotope composition that does not match known irons meteorite groups that were once planetesimal cores.

The dynamical corotation torque arising from the deformation of the horseshoe orbits, along with the vortensity gradient in the background disk, is important for determining orbital migration rate and direction of low-mass planets. Previous two-dimensional studies predicted that the dynamical corotation torque is positive, decelerating the inward planet migration. In contrast, recent three-dimensional studies have shown that buoyancy resonance makes the dynamical corotation torque negative, accelerating the inward migration. In this paper, we study the dependence of the dynamical corotation torque on the thermal transport using three-dimensional simulations. We first show that our results are consistent with previous three-dimensional studies when the disk is fully adiabatic. In more realistic radiative disks, however, radiative diffusion suppresses the buoyancy resonance significantly, especially at high-altitude regions, and yields a positive dynamical corotation torque. This alleviates the issue of a rapid migration caused by the negative dynamical corotation torque in the adiabatic disks. Our results suggest that radiative diffusion together with stellar irradiation and accretion heating is needed to accurately describe the migration of low-mass planets.

We use the Very Long Baseline Array to conduct high precision astrometry of a sample of 33 compact, flat spectrum, variable radio sources in the direction of the Galactic plane (Becker et al. 2010). Although Becker et al. (2010) ruled out a few potential scenarios for the origin of the radio emission, the study could not rule out that these sources were black hole X-ray binaries (BHXBs). Most known BHXBs are first detected by X-ray or optical emission when they go into an outburst, leaving the larger quiescent BHXB population undiscovered. In this paper, we attempt to identify any Galactic sources amongst the Becker et al. (2010) sample by measuring their proper motions as a first step to finding quiescent BHXB candidates. Amongst the 33 targets, we could measure the proper motion of six sources. We find that G32.7193$-$0.6477 is a Galactic source and are able to constrain the parallax of this source with a 3$\sigma$ significance. We found three strong Galactic candidates, G32.5898$-$0.4468, G29.1075$-$0.1546, and G31.1494$-$0.1727, based purely on their proper motions, and suggest that G29.1075$-$0.1546, is also likely Galactic. We detected two resolved targets for multiple epochs (G30.1038+0.3984 and G29.7161$-$0.3178). We find six targets are only detected in one epoch and have an extended structure. We cross-match our VLBA detections with the currently available optical, infrared and X-ray surveys, and did not find any potential matches. We did not detect 19 targets in any VLBA epochs and suggest that this could be due to limited $uv$-coverage, drastic radio variability or faint, extended nature of the sources.

We present SIPGI, a spectroscopic pipeline to reduce optical/near-infrared data from slit-based spectrographs. SIPGI is a complete spectroscopic data reduction environment which retains the high level of flexibility and accuracy typical of the standard "by-hand" reduction methods but is characterized by a significantly higher level of efficiency. This is obtained by exploiting three main concepts: $i)$ the instrument model: at the core of the data reduction is an analytic description of the main calibration relations (e.g. spectra location and wavelength calibration) that can be easily checked and adjusted on data using a graphical tool; $ii)$ a built-in data organizer that classifies the data, together with a graphical interface that helps in providing the recipes with the correct input; $iii)$ the design and flexibility of the reduction recipes: the number of tasks required to perform a complete reduction is minimized, while preserving the possibility of verifying the accuracy of the main stages of data-reduction process with provided tools. The current version of SIPGI manages data from the MODS and LUCI spectrographs mounted at the Large Binocular Telescope, and it is our plan to extend SIPGI to support other through-slit spectrographs. Meanwhile, to allow using the same approach based on the instrument model with other instruments, we have developed SpectraPy, a spectrograph independent Python library working on through-slit spectra. In its current version, SpectraPy produces two-dimensional wavelength calibrated spectra corrected by instrument distortions. The current release of SIPGI and its documentation can by downloaded from this http URL, while SpectraPy can be found at this http URL

Understanding the physics of star formation is one of the key problems facing modern astrophysics. The Cosmic Infrared Background (CIB), sourced by the emission from all dusty star-forming galaxies since the epoch of reionisation, is a complementary probe to study the star formation history, as well as an important extragalactic foreground for studies of the Cosmic Microwave Background (CMB). Understanding the physics of the CIB is therefore of high importance for both cosmology and galaxy formation studies. In this paper, we make high signal-to-noise measurements of the cross-correlation between maps of the CIB from the Planck experiment, and cosmic shear measurements from the Dark Energy Survey and Kilo-Degree Survey. Cosmic shear, sourced mainly by the weak gravitational lensing of photons emitted by background galaxies, is a direct tracer of the matter distribution, and thus we can use its cross-correlation with the CIB to directly test our understanding of the link between the star formation rate (SFR) density and the matter density. We use our measurements to place constraints on a halo-based model of the SFR that parametrises the efficiency with which gas is transformed into stars as a function of halo mass and redshift. These constraints are enhanced by combining our data with model-independent measurements of the bias-weighted SFR density extracted from the tomographic cross-correlation of galaxies and the CIB. We are able to place constraints on the peak efficiency at low redshifts, $\eta=0.445^{+0.055}_{-0.11}$, and on the halo mass at which this peak efficiency is achieved today $\log_{10}(M_1/M_\odot) = 12.17\pm0.25$. Our constraints are in excellent agreement with direct measurements of the SFR density, as well as other CIB-based studies.

In preparation for future space-borne gravitational-wave (GW) detectors, should the modelling effort focus on high-precision vacuum templates or on the the astrophysical environment of the sources? We perform a systematic comparison of the phase contributions caused by 1) known environmental effects in both gaseous and stellar matter backgrounds, or 2) high-order post-Newtonian terms in the evolution of mHz GW sources. We use the accuracy of currently available analytical waveform models as a benchmark and find the following trends: the largest unmodelled contributions are likely environmental for binaries lighter than $\sim 10^7/(1+z)^2$~M$_{\odot}$, where $z$ is the redshift. Binaries heavier than $\sim 10^8/(1+z)$~M$_{\odot}$ do not require more accurate waveforms due to low signal-to-noise ratios (SNRs). For high-SNR sources, environmental influences are relevant at low redshift, while high-order vacuum templates are required at $z > 4$. Led by these findings, we argue that including environmental effects in waveform models should be prioritised in order to maximize the science yield of mHz detectors.

A new experimental area, the NEAR station, has recently been built at the CERN n TOF facility, at a short distance from the spallation target (1.5 m). The new area, characterized by a neutron beam of very high flux, has been designed with the purpose of performing activation measurements of interest for astrophysics and various applications. The beam is transported from the spallation target to the NEAR station through a hole in the shielding wall of the target, inside which a collimator is inserted. The new area is complemented with a {\gamma}-ray spectroscopy laboratory, the GEAR station, equipped with a high efficiency HPGe detector, for the measurement of the activity resulting from irradiation of a sample in the NEAR station. The use of a moderator/filter assembly is envisaged, in order to produce a neutron beam of Maxwellian shape at different thermal energies, necessary for the measurement of Maxwellian Averaged Cross Sections of astrophysical interest. A new fast-cycling activation technique is also being investigated, for measurements of reactions leading to isotopes of very short half life.

In this short review, we discuss how Earth's climatological and geological history and also how the shadows of galactic black holes might reveal our Universe's past evolution. Specifically we point out that a pressure singularity that occurred in our Universe's past might have left its imprint on Earth's geological and climatological history and on the shadows of cosmological black holes. Our approach is based on the fact that the $H_0$ tension problem may be resolved if some sort of abrupt physics change occurred in our Universe $70-150\,$Myrs ago, an abrupt change that deeply affected the Cepheid parameters. We review how such an abrupt physics change might have been caused in our Universe by a smooth passage of it through a pressure finite-time singularity. Such finite-time singularities might occur in modified gravity and specifically in $F(R)$ gravity, so we show how modified gravity might drive this type of evolution, without resorting to peculiar cosmic fluids or scalar fields. The presence of such a pressure singularity can distort the elliptic trajectories of bound objects in the Universe, causing possible geological and climatological changes on Earth, if its elliptic trajectory around the Sun might have changed. Also, such a pressure singularity affects directly the circular photon orbits around supermassive galactic black holes existing at cosmological redshift distances, thus the shadows of some cosmological black holes at redshifts $z\leq 0.01$, might look different in shape, compared with the SgrA* and M87* supermassive black holes. This feature however can be checked experimentally in the very far future.

Is Dark Matter part of a Dark Sector? The possibility of a dark sector neutral under Standard Model (SM) forces furnishes an attractive explanation for the existence of Dark Matter (DM), and is a compelling new-physics direction to explore in its own right, with potential relevance to fundamental questions as varied as neutrino masses, the hierarchy problem, and the Universe's matter-antimatter asymmetry. Because dark sectors are generically weakly coupled to ordinary matter, and because they can naturally have MeV-to-GeV masses and respect the symmetries of the SM, they are only mildly constrained by high-energy collider data and precision atomic measurements. Yet upcoming and proposed intensity-frontier experiments will offer an unprecedented window into the physics of dark sectors, highlighted as a Priority Research Direction in the 2018 Dark Matter New Initiatives (DMNI) BRN report. Support for this program -- in the form of dark-sector analyses at multi-purpose experiments, realization of the intensity-frontier experiments receiving DMNI funds, an expansion of DMNI support to explore the full breadth of DM and visible final-state signatures (especially long-lived particles) called for in the BRN report, and support for a robust dark-sector theory effort -- will enable comprehensive exploration of low-mass thermal DM milestones, and greatly enhance the potential of intensity-frontier experiments to discover dark-sector particles decaying back to SM particles.

Deriving governing equations of complex physical systems based on first principles can be quite challenging when there are certain unknown terms and hidden physical mechanisms in the systems. In this work, we apply a deep learning architecture to learn fluid partial differential equations (PDEs) of a plasma system based on the data acquired from a fully kinetic model. The learned multi-moment fluid PDEs are demonstrated to incorporate kinetic effects such as Landau damping. Based on the learned fluid closure, the data-driven, multi-moment fluid modeling can well reproduce all the physical quantities derived from the fully kinetic model. The calculated damping rate of Landau damping is consistent with both the fully kinetic simulation and the linear theory. The data-driven fluid modeling of PDEs for complex physical systems may be applied to improve fluid closure and reduce the computational cost of multi-scale modeling of global systems.

We briefly review the recent novel solution of General Relativity, we call the cosmological black hole, firstly discovered in [Roupas, Z. Eur. Phys. J. C 82, 255 (2022)]. A dark energy universe and a Schwartzschild black hole are matched on a common dual event horizon which is finitely thick due to quantum indeterminacy. The system gets stabilized by a finite tangential pressure applied on the dual horizon. The fluid entropy of the system at a Tolman temperature identified with the cosmological horizon temperature is calculated to be equal with the Bekenstein-Hawking entropy.

In this note, we present a pedagogical illustration of peculiar properties of motion in the vicinity and inside black holes. We discuss how a momentary impulse can modify the lifetime of an object radially falling into a Schwarzschild black hole down to singularity. The well known upper limit for a proper time spent within a horizon, in fact, requires an infinitely powerful kick. We calculate the proper time interval (perceived as personal lifetime of a falling observer) till the contact with the singularity, as well as the time interval in the Lema\^itre frame (which reflects how far into the future of the outer world a falling observer can look), for different values of the kick received by the falling body. We discuss the ideal strategy to increase both time intervals by the engine with a finite power. This example is suitable for university seminars for undergraduate students specializing in General Relativity and related astrophysical subjects.

The need of reconciling our understanding of the behavior of hadronic matter across a wide range of densities, especially at the time when data from multimessenger observations and novel experimental facilities are flooding in, has provided new challenges to the nuclear models. Particularly, the density dependence of the isovector channel of the nuclear energy functionals seems hard to pin down if experiments like PREX-II (or PREX) and CREX are required to be taken on the same footing. We put to test this anomaly in a semi-agnostic modelling technique, by performing a full Bayesian analysis of static properties of neutron stars, together with global properties of nuclei as binding energy, charge radii and neutron skin calculated at the semi-classical level. Our results show that the interplay between bulk and surface properties, and the importance of high order empirical parameters that effectively decouple the subsaturation and the supersaturation density regime, might partially explain the tension between the different measurements and observations. If the surface behaviors, however, are decoupled from the bulk properties, we found a rather harmonious situation among experimental and observational data.

This is a summary of White Papers on micro-pattern gaseous detectors, submitted to Instrumentation Frontier Group 'IF5', as part of the Snowmass 2021 decadal survey of particle physics.

The properties of an axisymmetric, stationary gas cloud surrounding a massive central object are discussed. It is assumed that the gravitational field is dominated by the central object which is modeled by a nonrelativistic rotationally-symmetric potential. Further, we assume that the gas consists of collisionless, identical massive particles that follow bound orbits in this potential. Several models for the one-particle distribution function are considered and the essential formulae that describe the relevant macroscopical observables, such as the particle and energy densities, pressure tensor, and the kinetic temperature are derived. The asymptotic decay of the solutions at infinity is discussed and we specify configurations with finite total mass, energy and (zero or non-zero) angular momentum. Finally, our configurations are compared to their hydrodynamic analogs. In an accompanying paper, the equivalent general relativistic problem is discussed, where the central object consists of a Schwarzschild black hole.

The properties of a stationary gas cloud surrounding a black hole are discussed, assuming that the gas consists of collisionless, identical massive particles that follow spatially bound geodesic orbits in the Schwarzschild spacetime. Several models for the one-particle distribution function are considered, and the essential formulae that describe the relevant macroscopic observables, like the current density four-vector and the stress-energy-momentum tensor are derived. This is achieved by rewriting these observables as integrals over the constants of motion and by a careful analysis of the range of integration. In particular, we provide configurations with finite total mass and angular momentum. Differences between these configurations and their nonrelativistic counterparts in a Newtonian potential are analyzed. Finally, our configurations are compared to their hydrodynamic analogues, the "polish doughnuts".

The shear modulus of neutron star matter is one of the important properties for determining torsional oscillations in neutron stars. We take into account the effects of finite sizes of spherical nuclei on the shear modulus and examine the frequencies of crustal torsional oscillations. The shear modulus decreases owing to the finite-size effect, which in turn decreases the frequencies of torsional oscillations. In particular, the finite-size effect becomes more crucial for oscillations with a larger azimuthal quantum number and for neutron star models with a weaker density dependence of nuclear symmetry energy. In practice, when one identifies the quasi-periodic oscillations from a neutron star, where the magnetic effect is negligible, with crustal torsional oscillations, the finite-size effect can be more significant at frequencies higher than $\sim 100$ Hz.

The self-force is the leading method in modelling waveforms for extreme mass ratio inspirals, a key target of ESA's future space-based gravitational wave detector LISA. In modelling these systems, one approximates the smaller body as a point particle leading to problematic singularities that need to be removed. Modelling of this singular structure has settled on the Detweiler-Whiting singular field as the gold standard. As a solution to the governing wave equation itself, on removal, it leaves a smooth regular field that is a solution to the homogeneous wave equation, much like its well established flat spacetime counterpart. The mode-sum method enables subtraction of this singularity mode by mode via a spherical harmonic decomposition. The more modes one has, the faster the convergence in the $\ell$-sum, making these expressions highly beneficial, especially considering the heavy computational burden of waveform production. Until recently, only the two leading orders were known for generic orbits in Kerr spacetime. In a previous paper, we produced the next non-zero parameter for a scalar charged particle in curved spacetime, laying the groundwork for the electromagnetic and gravitational case which we present here.

Gaussian noise is an irreducible component of the background in gravitational wave (GW) detectors. Although stationary Gaussian noise is uncorrelated in frequencies, we show that there is an important correlation in time when looking at the matched filter signal to noise ratio (SNR) of a template, with a typical autocorrelation time that depends on the template and the shape of the noise power spectral density (PSD). Taking this correlation into account, we compute from first principles the false alarm rate (FAR) of a template in Gaussian noise, defined as the number of occurrences per unit time that the template's matched filter SNR goes over a threshold $\rho$. We find that the Gaussian FAR can be well approximated by the usual expression for uncorrelated noise, if we replace the sampling rate by an effective sampling rate that depends on the parameters of the template, the noise PSD and the threshold $\rho$. This results in a minimum SNR threshold that has to be demanded to a given GW trigger, if we want to keep events generated from Gaussian noise below a certain FAR. We extend the formalism to multiple detectors and to the analysis of GW events. We apply our method to the GW candidates added in the GWTC-3 catalog, and discuss the possibility that GW200308\_173609 and GW200322\_091133 could be generated by Gaussian noise fluctuations.