Papers for Tuesday, May 10 2022

The IceCube Neutrino Observatory at the South Pole has measured astrophysical neutrinos using through-going and starting events in the TeV to PeV energy range. The origin of these astrophysical neutrinos is still largely unresolved, and among their potential sources could be dark matter decay. Measurements of the astrophysical flux using muon neutrinos are in slight tension with starting event measurements. This tension is driven by an excess observed in the energy range of 40-200 TeV with respect to the through-going expectation. Previous works have considered the possibility that this excess may be due to heavy dark matter decay and have placed constraints using gamma-ray and neutrino data. However, these constraints are not without caveats since they rely on the modeling of the astrophysical neutrino flux and the sources of gamma-ray emission. In this work, we derive background-agnostic galactic and extragalactic constraints on decaying dark matter by considering Tibet AS$_\gamma$ data, Fermi-LAT diffuse data, and the IceCube high-energy starting event sample. For the gamma-ray limits, we investigate the uncertainties on secondary emission from electromagnetic cascades during propagation arising from the unknown intensity of the extragalactic background light. We find that such uncertainties amount to a variation of up to $\sim 55\%$ in the gamma-ray limits derived with extragalactic data. Our results imply that a significant fraction of the astrophysical neutrino flux could be due to dark matter and that ruling it out depends on the assumptions on the gamma-ray and neutrino background. The latter depends on the yet unidentified sources.

We present the discovery of the first millimeter afterglow of a short-duration $\gamma$-ray burst (SGRB) and the first confirmed afterglow of an SGRB localized by the GUANO system on Swift. Our Atacama Large Millimeter/Sub-millimeter Array (ALMA) detection of SGRB 211106A solidifies an origin in a faint host galaxy detected in Hubble Space Telescope (HST) imaging at a projected separation of $\approx0.8$ kpc. The millimeter-band light curve captures the passage of the synchrotron peak from the afterglow forward shock, constraining the afterglow kinetic energy, $\log(E_{\rm K,iso}/{\rm erg})=53.2\pm0.3$ and density, $\log(n_0/{\rm cm}^{-3})=-0.6\pm0.2$ at a presumed redshift of $z=1$. We identify a jet break at $t_{\rm jet}=29.2^{+4.5}_{-4.0}$ days in the millimeter-band data and infer an opening angle of $\theta_{\rm jet}=(15.5\pm1.4)$ degrees and beaming-corrected kinetic energy of $\log(E_{\rm K}/{\rm erg})=54.3\pm0.3$, which are the widest and highest ever measured for an SGRB, respectively. From the lack of a detectable optical afterglow, coupled with the bright millimeter counterpart, we infer a high extinction, $A_{\rm V}\gtrsim2.6$ mag along the line of sight, making this the one of the most highly dust-extincted SGRBs known to date. Combining all published millimeter-band upper limits in conjunction with the energetics for a large sample of SGRBs, we find that energetic, wide-angled outflows in high density environments are more likely to have detectable millimeter counterparts. Concerted afterglow searches with ALMA should yield detection fractions of 24--40\% on timescales of $>2$ days at rates $\approx0.8$--1.6 per year, outpacing the historical discovery rate of SGRB centimeter-band afterglows.

The density profiles of dark matter haloes are commonly described by fitting functions such as the NFW or Einasto models, but these approximations break down in the transition region where halos become dominated by newly accreting matter. In Paper I we dynamically split simulation particles into orbiting and infalling components and analysed their separate profiles. Here we propose simple, accurate fitting functions designed to capture the asymptotic shapes of the two terms at large and small radii. The orbiting term is described as a truncated Einasto profile, $\rho_{\rm orb} \propto \exp \left[-2/\alpha\ (r / r_{\rm s})^\alpha - 1/\beta\ (r / r_{\rm t})^\beta \right]$, with a five-parameter space of normalization, physically distinct scale and truncation radii, and $\alpha$ and $\beta$, which control how rapidly the profiles steepen. The infalling profile is modelled as a power law in overdensity that smoothly transitions to a constant at the halo centre. We show that these formulae fit the averaged, total profiles in simulations to about 5% accuracy across almost all of an expansive parameter space in halo mass, redshift, cosmology, and accretion rate. When fixing $\alpha = 0.18$ and $\beta = 3$, the formula becomes a three-parameter model for the orbiting term that fits individual halos better than the Einasto profile on average.

The kinetic Sunyaev Zel'dovich effect is a secondary CMB temperature anisotropy that provides a powerful probe of the radial-velocity field of matter distributed across the Universe. This velocity field is reconstructed by combining high-resolution CMB measurements with galaxy survey data, and it provides an unbiased tracer of matter perturbations in the linear regime. In this paper, we show how this measurement can be used to probe primordial non-gaussianity of the local type, particularly focusing on the trispectrum amplitude $\tau_{\rm NL}$, as may arise in a simple two-field inflation model that we provide by way of illustration. Cross-correlating the velocity-field-derived matter distribution with the biased large-scale galaxy density field allows one to measure the scale-dependent bias factor with sample variance cancellation. We forecast that a configuration corresponding to CMB-S4 and VRO results in a sensitivity of $\sigma_{f_{\rm NL}} \approx 0.39$ and $\sigma_{\tau_{\rm NL}} \approx 0.23$. These forecasts predict improvement factors of 10 and 95 for $\sigma_{f_{\rm NL}}$ and $\sigma_{\tau_{\rm NL}}$, respectively, over the sensitivity using VRO data alone, without internal sample variance cancellation. Similarly, for a configuration corresponding to DESI and SO, we forecast a sensitivity of $\sigma_{f_{\rm NL}} \approx 2.3$ and $\sigma_{\tau_{\rm NL}} \approx 12$, with improvement factors of 2 and 3, respectively, over the use of the DESI data-set in isolation. We find that a high galaxy number density and large survey volume considerably improve our ability to probe the amplitude of the primordial trispectrum for the multi-field model considered.

Context: The Ophiuchus cluster of galaxies, located at low latitudes in the direction of the Galactic bulge, has been relatively poorly studied in comparison with other rich galaxy clusters like Coma, Virgo and Fornax, in spite of being the 2nd brightest X-ray cluster in the sky. Methods: Deep near-infrared images and photometry from the VISTA Variables in the V\'ia L\'actea eXtended survey (VVVX) were used to detect galaxy member candidates of Ophiuchus cluster up to 2 Mpc from the cD galaxy 2MASX J17122774-2322108 using the Galdeano et al. criteria to select the galaxies among the foreground sources. We also perform a morphological visual classification, color-magnitude diagram and density profiles. Results: We identified 537 candidate galaxy members of the Ophiuchus cluster up to 2 Mpc from the cD galaxy, increasing 7 times the number of galaxies reported in previous catalogs. In addition, we performed a morphological classification of these galaxy candidates finding that the fraction of Ellipticals reaches more than the 60% in the central region of the cluster. On the other hand the Spirals fraction is lower than the 20% remaining almost constant throughout the cluster. Moreover, we study the red sequence of galaxy member candidates and use mock catalogs to explore the density profile of the cluster, finding that the value derived from the mock catalog towards an overdense region is in agreement with the galaxy excess of the central zone of the Ophiuchus cluster. Conclusions: Our investigation of the hidden population of Ophiuchus galaxies underscores the importance of this cluster as a prime target for future photometric and spectroscopic studies. Moreover the results of this work highlights the potential of VVVX survey to study extragalactic objects in the Zone of Avoidance.

We present a nearly complete rapid neutron-capture process (r-process) chemical inventory of the metal-poor ([Fe/H] = -1.46 +/- 0.10) r-process-enhanced ([Eu/Fe] = +1.32 +/- 0.08) halo star HD 222925. This abundance set is the most complete for any object beyond the solar system, totaling 63 metals detected and 7 with upper limits. It comprises 42 elements from 31 <= Z <= 90, including elements rarely detected in r-process-enhanced stars, such as Ga, Ge, As, Se, Cd, In, Sn, Sb, Te, W, Re, Os, Ir, Pt, and Au. We derive these abundances from an analysis of 404 absorption lines in ultraviolet spectra collected using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope and previously analyzed optical spectra. A series of appendices discusses the atomic data and quality of fits for these lines. The r-process elements from Ba to Pb, including all elements at the third r-process peak, exhibit remarkable agreement with the Solar r-process residuals, with a standard deviation of the differences of only 0.08 dex (17%). In contrast, deviations among the lighter elements from Ga to Te span nearly 1.4 dex, and they show distinct trends from Ga to Se, Nb through Cd, and In through Te. The r-process contribution to Ga, Ge, and As is small, and Se is the lightest element whose production is dominated by the r-process. The lanthanide fraction, log(X_La) = -1.40 +/- 0.09, is typical for r-process-enhanced stars and higher than that of the kilonova from the GW170817 neutron-star merger event. We advocate adopting this pattern as an alternative to the Solar r-process-element residuals when confronting future theoretical models of heavy-element nucleosynthesis with observations.

We present the results of a search for deeply-eclipsing white dwarfs in the ZTF Data Release 4. We identify nine deeply-eclipsing white dwarf candidates, four of which we followed up with high-cadence photometry and spectroscopy. Three of these systems show total eclipses in the ZTF data and our follow-up APO 3.5-meter telescope observations. Even though the eclipse duration is consistent with sub-stellar companions, our analysis shows that all four systems contain a white dwarf with low-mass stellar companions of ~0.1 Msol. We provide mass and radius constraints for both stars in each system based on our photometric and spectroscopic fitting. Finally, we present a list of 41 additional eclipsing WD+M candidates identified in a preliminary search of ZTF DR7, including 12 previously studied systems. We identify two new candidate short-period, eclipsing, white dwarf-brown dwarf binaries within our sample of 41 WD+M candidates based on PanSTARRS colors.

The VISTA Variables in the Via L\'actea Extended Survey (VVVX) allows probing previously unexplored regions of the inner Milky Way (MW). We are looking for new candidate globular clusters (GCs), with the aim of completing the census of the MW GC system. We searched and characterised new GCs, using a combination of the near-IR VVVX survey and 2MASS datasets, and the optical Gaia EDR3 photometry and its precise proper motions (PMs). We report the discovery of a new Galactic GC, named Garro 02, situated at RA=18:05:51.1, Dec=-17:42:02 and l=12.042 deg, b=+1.656 deg. Performing a PM-decontamination procedure, we built a final catalogue with all cluster members, on which we performed a photometric analysis. We calculated a reddening of $E(J-K_s)=1.07\pm 0.06$ mag and extinction of $A_{Ks}=0.79\pm 0.04$ mag in the near-IR; while $E(BP-RP)=2.40\pm 0.01$ mag and $A_{G}=4.80\pm 0.02$ mag in optical passbands. Its heliocentric distance is $D=5.6\pm 0.8$ kpc, which places Garro 02 at a Galactocentric distance of $R_G=2.9$ kpc and Z=0.006 kpc above the Galactic plane. We estimated the metallicity and age by comparison with known GCs and by fitting PARSEC isochrones, finding [Fe/H]$=-1.30\pm 0.2$ dex and age=$12\pm 2$ Gyr. We derived the mean cluster PM of $(\mu_{\alpha}^{\ast}, \mu_{\delta}) = (-6.07\pm 0.62, -6.15\pm 0.75)$ mas yr$^{-1}$. We calculated the cluster luminosity in the near-IR of $M_{Ks}=-7.52\pm 1.23$ mag, which is equivalent to $M_{V}=-5.44$ mag. The core and tidal radii from the radial density profile are $r_c =1.25\pm 0.27$ arcmin (2.07 pc) and $r_t = 7.13\pm 3.83$ arcmin (11.82 pc), respectively. We confirm Garro 02 as a new genuine Galactic GC, located in the MW bulge. It is a low-luminosity, metal-poor, and old GC, and it is a lucky survivor of the strong dynamical processes that occurred during the MW's entire life.

The Laser Interferometer Space Antenna (LISA) will detect and characterize $\sim10^4$ Galactic Binaries consisting predominantly of two White Dwarfs (WD). An interesting prospect within this population is a third object--another WD star, a Circumbinary Exoplanet (CBP), or a Brown Dwarf (BD)--in orbit about the inner WD pair. We present the first fully Bayesian detection and posterior analysis of sub-stellar objects with LISA, focusing on the characterization of CBPs. We used an optimistic astrophysically motivated catalogue of these CBP third-body sources, including their orbital eccentricity around the inner binary for the first time. We examined Bayesian Evidence computations for detectability, as well as the effects on the posterior distributions for both the inner binary parameters and the third-body parameters. We find that the posterior behavior bifurcates based on whether the third-body period is above or below half the observation time. Additionally, we find that undetectable third-body sources can bias the inner binary parameters whether or not the correct template is used. We used the information retrieved from the study of the CBP population to make an initial conservative prediction for the number of detectable BD systems in the original catalogue. We end with commentary on the predicted qualitative effects on LISA global fitting and Galactic Binary population analysis. The procedure used in this work is generic and can be directly applied to other astrophysical effects expected within the Galactic Binary population.

The unexplained excess gamma-ray emission from the Milky Way's Galactic Center has puzzled astronomers for nearly a decade. Two theories strive to explain the origin of this excess: self-annihilating dark matter particles or an unresolved population of radio millisecond pulsars. We examine the plausibility of a pulsar origin for the GeV excess using N-body simulations. We simulated millisecond pulsars in a realistic dynamical environment: (i) pulsars were born from the known stellar mass components of our Galaxy; (ii) pulsars were given natal velocity kicks as empirically observed from two different studies (or, for comparison, without kicks); (iii) pulsars were evolved in a Galactic gravitational potential consistent with observations. Multiple populations of pulsars (with different velocity kicks) were simulated over 1 Gyr. With final spatial distributions of pulsars, we constructed synthetic gamma-ray surface brightness profiles. From comparisons with published Fermi-LAT surface brightness profiles, our pulsar simulations cannot reproduce the concentrated emission in the central degrees of the Bulge, though models without natal velocity kicks approach the data. We considered additive combinations of our (primordial MSP) simulations with models where pulsars are deposited from destroyed globular clusters in the Bulge, and a simple model for pulsars produced in the nuclear star cluster. We can reasonably reproduce the measured central gamma-ray surface brightness distribution of Horiuchi and collaborators using several combinations of these models, but we cannot reproduce the measured distribution of Di Mauro with any combination of models. Our fits provide constraints on potential pathways to explain the gamma-ray excess using MSPs.

We report a decaying kink oscillation of a flux rope during a confined eruptive flare, observed off the solar limb by SDO/AIA, that lacked a detectable white-light coronal mass ejection. The erupting flux rope underwent kinking, rotation, and apparent leg-leg interaction during the event. The oscillations were observed simultaneously in multiple AIA channels at 304, 171, and 193 {\AA}, indicating that multithermal plasma was entrained in the rope. After reaching the overlying loops in the active region, the flux rope exhibited large-amplitude, decaying kink oscillations with an apparent initial amplitude of 30 Mm, period of about 16 min, and decay time of about 17 min. We interpret these oscillations as a fundamental standing kink mode of the flux rope. The oscillation polarization has a clear vertical component, while the departure of the detected waveform from a sinusoidal signal suggests that the oscillation could be circularly or elliptically polarized. The estimated kink speed is 1080 km/s, corresponding to an Alfv\'en speed of about 760 km/s. This speed, together with the estimated electron density in the rope from our DEM analysis, $n_e \approx$(1.5--2.0)$\times 10^9$cm$^{-3}$, yields a magnetic field strength of about 15 G. To the best of our knowledge, decaying kink oscillations of a flux rope with non-horizontal polarization during a confined eruptive flare have not been reported before. These oscillations provide unique opportunities for indirect measurements of the magnetic-field strength in low-coronal flux ropes during failed eruptions.

Thanks to asteroseismology, constraints on the core rotation rate are available for hundreds of low- and intermediate-mass stars in evolved phases. Current physical processes tested in stellar evolution models cannot reproduce the evolution of these core rotation rates. We investigate the efficiency of the internal angular momentum redistribution in red giants during the hydrogen shell and core-helium burning phases based on the asteroseismic determinations of their core rotation rates. We compute stellar evolution models with rotation and model the transport of angular momentum by the action of a sole dominant diffusive process parametrized by an additional viscosity. We constrain the values of this viscosity to match the mean core rotation rates of red giants and their behaviour with mass and evolution along the red giant branch and in the red clump. For red giants in the hydrogen shell-burning phase the transport of angular momentum must be more efficient in more massive stars. The additional viscosity is found to vary by approximately two orders of magnitude in the mass range M $\sim$ 1 - 2.5 M$_{\odot}$. As stars evolve along the red giant branch, the efficiency of the internal transport of angular momentum must increase for low-mass stars (M $\lesssim$ 2 M$_{\odot}$) and remain approximately constant for slightly higher masses (2.0 M$_{\odot}$ $\lesssim$ M $\lesssim$ 2.5 M$_{\odot}$). In red-clump stars, the additional viscosities must be an order of magnitude higher than in younger red giants of similar mass during the hydrogen shell-burning phase. In combination with previous efforts, we obtain a clear picture of how the physical processes acting in stellar interiors should redistribute angular momentum from the end of the main sequence until the core-helium burning phase for low- and intermediate-mass stars to satisfy the asteroseismic constraints.

As the powerhouse of our solar system, the Sun's electromagnetic planetary influences appear contradictory. On the one hand, the Sun for aeons emitted radiation which was "just right" for life to evolve in our terrestrial Goldilocks zone, even for such complex organisms as ourselves. On the other, in the dawn of Earth's existence the Sun was far dimmer than today, and yet evidence for early liquid water is written into geology. Now in middle age, the Sun should be a benign object of little interest to society or even astronomers. However, for physical reasons yet to be fully understood, it contains a magnetic machine with a slightly arrhythmic 11 year magnetic heartbeat. Although these variations require merely 0.1% of the solar luminosity, this power floods the solar system with rapidly changing fluxes of photons and particles at energies far above the 0.5eV thermal energy characteristic of the photosphere. Ejected solar plasma carries magnetic fields into space with consequences for planets, the Earth being vulnerable to geomagnetic storms. This chapter discusses some physical reasons why the Sun suffers from such ailments, and examine consequences through time across the solar system. A Leitmotiv of the discussion is that any rotating and convecting star must inevitably generate magnetic "activity" for which the Sun represents the example par excellence.

Studying Ultraluminous X-ray sources (ULXs) in the optical wavelengths provides important clues about the accretion mechanisms and the evolutionary processes of X-ray binary systems. In this study, three (C1, C2, and C3) possible optical counterparts were identified for well-known neutron star (NS) candidate M51 ULX-8 through advanced astrometry based on the Chandra and Hubble Space Telescope (HST) observations, as well as the {\it GAIA} optical source catalogue. Optical periodic modulation of 125.5 days with an amplitude of 0.14 magnitude was determined for C3 which has evidence to represent the optical nature of ULX-8 using one-year (2016-2017) 34 HST ACS (Advanced Camera for Surveys)/WFC (Wide Field Camera) observations. Moreover, surprisingly it was also found that the X-ray fluxes and also the observed optical fluxes of C3 exhibit a bi-modal distribution. This could mean that there is a possible correlation between the optical fluxes and the X-ray fluxes of the ULX-8. The possible scenarios which are frequently mentioned in the literature proposed for the nature of optical emission and optical super-orbital period. The most probable scenario is that the optical emission could have originated from the accretion disk of the ULX-8.

Extreme-ultraviolet late phase (ELP) refers to the second extreme-ultraviolet (EUV) radiation enhancement observed in certain solar flares, which usually occurs tens of minutes to several hours after the peak of soft X-ray emission. The coronal loop system that hosts the ELP emission is often different from the main flaring arcade, and the enhanced EUV emission therein may imply an additional heating process. However, the origin of the ELP remains rather unclear. Here we present the analysis of a C1.4 flare that features such an ELP, which is also observed in microwave wavelengths by the Expanded Owens Valley Solar Array (EOVSA). Similar to the case of the ELP, we find a gradual microwave enhancement that occurs about three minutes after the main impulsive phase microwave peaks. Radio sources coincide with both footpoints of the ELP loops and spectral fits on the time-varying microwave spectra demonstrate a clear deviation of the electron distribution from the Maxwellian case, which could result from injected nonthermal electrons or nonuniform heating to the footpoint plasma. We further point out that the delayed microwave enhancement suggests the presence of an additional heating process, which could be responsible for the evaporation of heated plasma that fills the ELP loops, producing the prolonged ELP emission.

Interplanetary coronal mass ejections (ICMEs) are one of the main drivers for space weather disturbances. In the past, different approaches have been used to automatically detect events in existing time series resulting from solar wind in situ observations. However, accurate and fast detection still remains a challenge when facing the large amount of data from different instruments. For the automatic detection of ICMEs we propose a pipeline using a method that has recently proven successful in medical image segmentation. Comparing it to an existing method, we find that while achieving similar results, our model outperforms the baseline regarding training time by a factor of approximately 20, thus making it more applicable for other datasets. The method has been tested on in situ data from the Wind spacecraft between 1997 and 2015 with a True Skill Statistic (TSS) of 0.64. Out of the 640 ICMEs, 466 were detected correctly by our algorithm, producing a total of 254 False Positives. Additionally, it produced reasonable results on datasets with fewer features and smaller training sets from Wind, STEREO-A and STEREO-B with True Skill Statistics of 0.56, 0.57 and 0.53, respectively. Our pipeline manages to find the start of an ICME with a mean absolute error (MAE) of around 2 hours and 56 minutes, and the end time with a MAE of 3 hours and 20 minutes. The relatively fast training allows straightforward tuning of hyperparameters and could therefore easily be used to detect other structures and phenomena in solar wind data, such as corotating interaction regions.

We present a long term optical $R$ band light curve analysis of the gravitationally lensed blazar AO 0235+164 in the time span 1982 - 2019. Several methods of analysis lead to the result that there is a periodicity of ~8.13 years present in these data. In addition, each of these five major flares are apparently double-peaked, with the secondary peak following the primary one by ~2 years. Along with the well known system, OJ 287, our finding constitutes one of the most secure cases of long term quasi-periodic optical behaviour in a blazar ever found. A binary supermassive black hole system appears to provide a good explanation for these results.

The detection of astrophysical $\nu_\tau$ is an important verification of the observed flux of high-energy neutrinos. A flavour ratio of approximately $\nu_{e} : \nu_\mu : \nu_\tau \approx 1 : 1 : 1$ is predicted for astrophysical neutrinos measured at Earth due to neutrino oscillations. On top of this, the $\nu_\tau$ offers a unique channel for neutrino astronomy due to absence of an atmospheric $\nu_\tau$ background contribution. When a $\nu_\tau$ interacts it produces a particle cascade and often a $\tau$ lepton which in turn decays mainly into another cascade. This results in a double cascade signature. An excellent angular resolution can be achieved when both cascade vertices are reconstructed. The KM3NeT/ARCA detector, which is under construction in the Mediterranean sea, will be able to detect this signature due to its timing and spatial resolution for cascades. We will discuss the dedicated reconstruction algorithm and performance for reconstructing double cascades using KM3NeT. The angular deviation reaches sub-degree level for tau lengths larger than 25 meters.

We present the most extensive and well-sampled long-term multi-band near-infrared (NIR) temporal and spectral variability study of OJ 287, considered to be the best candidate binary supermassive black hole blazar. These observations were made between December 2007 and November 2021. The source underwent ~ 2 -- 2.5 magnitude variations in the J, H, and Ks NIR bands. Over these long-term timescales there were no systematic trends in either flux or spectral evolution with time or with the source's flux states. However, on shorter timescales, there are significant variations in flux and spectra indicative of strong changes during different activity states. The NIR spectral energy distributions show diverse facets at each flux state, from the lowest to the highest. The spectra are, in general, consistent with a power-law spectral profile (within 10%) and many of them indicate minor changes (observationally insignificant) in the shift of the peak. The NIR spectra generally steepens during bright phases. We briefly discuss these behaviors in the context of blazar emission scenarios/mechanisms, OJ 287's well-known traditional behavior, and implications for models of the source central engine invoked for its long-term optical semi-periodic variations.

The Polarized Instrument for Long-wavelength Observation of the Tenuous interstellar medium (PILOT) is a balloon-borne experiment that aims to measure the polarized emission of thermal dust at a wavelength of 240 um (1.2 THz). The PILOT experiment flew from Timmins, Ontario, Canada in 2015 and 2019 and from Alice Springs, Australia in April 2017. The in-flight performance of the instrument during the second flight was described in Mangilli et al. 2019. In this paper, we present data processing steps that were not presented in Mangilli et al. 2019 and that we have recently implemented to correct for several remaining instrumental effects. The additional data processing concerns corrections related to detector cross-talk and readout circuit memory effects, and leakage from total intensity to polarization. We illustrate the above effects and the performance of our corrections using data obtained during the third flight of PILOT, but the methods used to assess the impact of these effects on the final science-ready data, and our strategies for correcting them will be applied to all PILOT data. We show that the above corrections, and in particular that for the intensity to polarization leakage, which is most critical for accurate polarization measurements with PILOT, are accurate to better than 0.4 % as measured on Jupiter during flight#3.

We study weak gravitational lensing by the cosmic large-scale structure of the 21-cm radiation background in the 3d-weak lensing formalism. The interplay between source distance measured at finite resolution, visibility and lensing terms is analysed in detail and the resulting total covariance $C_{\ell}(k,k')$ is derived. The effect of lensing correlates different multipoles through convolution, breaking the statistical homogeneity of the 21-cm radiation background. This homogeneity breaking can be exploited to reconstruct the lensing field $\hat{\phi}_{\ell m}(\kappa)$ and noise lensing reconstruction $N_{\ell}^{\hat{\phi}}$ by means of quadratic estimators. The effects related to the actual measurement process (redshift precision and visibility terms) change drastically the values of the off-diagonal terms of the total covariance $C_{\ell}(k,k')$. It is expected that the detection of lensing effects on a 21-cm radiation background will require sensitive studies and high-resolution observations by future low-frequency radio arrays such as the SKA survey.

Carbon is produced during the helium burning phase of sufficiently massive stars through the triple alpha process. The $0^+$ energy level of the carbon nucleus allows for resonant nuclear reactions, which act to greatly increase the carbon yields compared to the non-resonant case. Many authors have argued that small changes to the energy level of this resonance would lead to a significantly lower carbon abundance in the universe, and this sensitivity is often considered an example of fine-tuning. By considering spallation reactions occuring during the process of planet formation, this paper presents a partial solution to this triple alpha fine-tuning problem. Young stellar objects generate substantial luminosities of particle radiation (cosmic rays) that can drive nuclear reactions through spallation. If the standard triple alpha process is inoperative, stars tend to synthesize oxygen (and other alpha elements) rather than carbon. Cosmic rays can interact with oxygen nuclei to produce carbon while planets are forming. The resulting carbon abundances are significant, but much smaller than those observed in our universe. However, for a range of conditions -- as delineated herein -- spallation reactions can result in carbon-to-oxygen ratios roughly comparable to those found on Earth and thereby obviate the triple alpha fine-tuning problem.

The diffuse flux of cosmic neutrinos has been measured by the IceCube Observatory from TeV to PeV energies. We show that an improved characterization of this flux at the lower energies, TeV and sub-TeV, reveals important information on the nature of the astrophysical neutrino sources in a model-independent way. Most significantly, it could confirm the present indications that neutrinos originate in cosmic environments that are optically thick to GeV-TeV $\gamma$-rays. This conclusion will become inevitable if a steeper or even uninterrupted neutrino power law is observed in the TeV region. In such $\gamma$-ray-obscured sources, the $\gamma$-rays that inevitably accompany cosmic neutrinos will cascade down to MeV-GeV energies. The requirement that the cascaded $\gamma$-ray flux accompanying cosmic neutrinos should not exceed the observed diffuse $\gamma$-ray background, puts constraints on the peak energy and density of the radiation fields in the sources. Our calculations inspired by the existing data suggest that a fraction of the observed diffuse MeV-GeV $\gamma$-ray background may be contributed by neutrino sources with intense radiation fields that obscure the high-energy $\gamma$-ray emission accompanying the neutrinos.

We study the formation and destruction of the first molecules at the epochs of the Dark Ages and Cosmic Dawn to evaluate the luminosity of the protogalaxy clumps (halos) in the molecular lines. The cosmological recombination is described using the model of an effective three-level atom, while the chemistry of the molecules is examined using the relevant basic kinetic equations. We then studied the effect of collisional and radiative excitation of molecules on the intensity of molecular emission in both warm and hot halos. Using the Planck data on the reionization of the intergalactic medium at z~6-8, we evaluated the upper limits of the light energy density for four models of thermal light from the first sources that appeared in the Cosmic Dawn epoch. Assuming that in the halos, the light energy density may essentially be even higher, we estimated the impact of the light from the first sources on the formation and destruction of the first molecules. We show that the molecules H2 and HD are destroyed by photodissociation processes shortly before the full reionization in the inter-halo medium, in the medium of both types of halos and for all models of the first light. At the same time, the number density of helium hydride ions, HeH+, shows essentially more complicated dependences on the kinetic temperature of halos and the models of the first light. Furthermore, we estimated the differential brightness temperature of the individual halo in the rotational lines of H2, HD and HeH+ molecules at redshifts corresponding to the Dark Ages and Cosmic Dawn epochs. It does not exceed the microkelvin, but its detection may be an important source of information about the physical processes taking place at the beginning of the formation of the first stars and galaxies at the epochs of the Dark Ages and Cosmic Dawn.

We introduce a new nonparametric representation of the neutron star (NS) equation of state (EoS) by using the variational auto-encoder (VAE). As a deep neural network, the VAE is widely used for dimensionality reduction since it can compress input data to a low dimensional latent space using the encoder component and then reconstruct the data using the decoder component. Once a VAE is trained one can take the decoder of the VAE as a generator. We employ 100,000 EoSs generated with the nonparametric representation method in \citet{2021ApJ...919...11H} as the training set and try different settings of the neural network, then get an EoS generator (trained VAE's decoder) with 4 parameters. We use the mass\textendash{}tidal-deformability data of binary neutron star (BNS) merger event GW170817, and the mass\textendash{}radius data of PSR J0030+0451, PSR J0740-6620, PSR J0437-4715, and 4U 1702-429 to perform the joint Bayesian inference. We find out that $R_{1.4}=12.66^{+0.71}_{-0.54}\,\rm km$, $\Lambda_{1.4}=484^{+118}_{-90}$, and $M_{\rm max}=2.30^{+0.30}_{-0.21}\,\rm M_\odot$ ($90\%$ credible levels), where $R_{1.4}$/$\Lambda_{1.4}$ are the radius/tidal-deformability of a canonical $1.4\,\rm M_\odot$ NS, and $M_{\rm max}$ is the maximum mass of a non-rotating NS.

Fast Radio Bursts (hereafter FRBs) can be used in cosmology by studying the Dispersion Measure (hereafter DM) as a function of redshift. The large scale structure of matter distribution is regarded as a major error budget for such application. Using optical galaxy and dispersion measure mocks built from N-body simulations, we have shown that the galaxy number density can be used as a tracer for large scale electron density and help improve the measurement of DM as a function of redshift. We have shown that, using the line-of-sight galaxy number counts within 1' around the given localized FRB source can help improve the cosmological parameter constraints by more than 20%.

The cores of neutron stars (NSs) near the maximum mass realize the most highly compressed matter in the universe where quark degrees of freedom may be liberated. Such a state of dense matter is hypothesized as quark matter (QM) and its presence has awaited to be confirmed for decades in nuclear physics. Gravitational waves from binary NS mergers are expected to convey useful information called the equation of state (EOS). However, the signature for QM with realistic EOS is not yet established. Here, we show that the gravitational wave in the post-merger stage can distinguish the theory scenarios with and without a transition to QM. Instead of adopting specific EOSs as studied previously, we compile reliable EOS constraints from the ab initio approaches. We demonstrate that early collapse to a black hole after NS merger signifies softening of the EOS associated with the onset of QM in accord with ab initio constraints. Nature of hadron-quark phase transition can be further constrained by the condition that electromagnetic counterparts need to be energized by the material left outside the remnant black hole.

Compact binary mergers involving at least one neutron star are promising sites for the synthesis of r-process elements found in stars and planets. However, mergers are generally thought to take place at high galactic latitudes, far from any star-forming regions of the host galaxy. It is thus important to understand the physical mechanisms involved in transporting enriched material from the gas environments of the galactic halo to the star-forming disk. We investigate these processes, starting from an explosive injection event and its interaction with the halo gas medium. We show that the total outflow mass in compact binary mergers is far too low for the material to travel to the disk in a ballistic fashion. Instead, the enriched ejecta is swept into a shell, which decelerates over $1-10$ pc scales, and becomes corrugated by the Rayleigh-Taylor instability. The corrugated shell is denser than the ambient medium, and breaks into clouds which then sink toward the disk. The sinking clouds lose thermal energy through radiative cooling, and are also ablated by shearing instabilities. We present a dynamical heuristic that models these effects, and would predict the delay times for delivery to the disk. However, we find that turbulent mass ablation is extremely efficient, and leads to the total fragmentation of sinking r-process clouds over $\sim 10^5$ yr. We thus predict that enriched material from halo injection events quickly assimilates into the gas medium of the halo, and that enriched mass flow to the disk could only be accomplished by turbulent diffusion or large-scale inflowing mass currents.

We present the catalogue of the TESS targets showing multiple eclipses. It means that in all of these stars we detected two sets of eclipses, for which their two distinctive periods can be derived. These multiple stellar systems can be either doubly eclipsing quadruples, or triple-star coplanar systems showing besides the inner eclipses also the eclipses on the outer orbit. In total, 116 systems were found as doubly eclipsing, while 25 stars were identified as triply eclipsing triples. Several confirmed blends of two close sources were not included into our analysis. All these systems were identified scanning the known eclipsing systems taken from VSX database checking their TESS light curves. The average period of the dominant pair A is 2.7 days in our sample, while for the second pair B the average period is 5.3 days. Several systems show evident ETV changes even from the short interval of the TESS data, indicating possible period changes and short mutual orbit. We also present an evidence that the system V0871 Cen is probably a septuple-star system of architecture (Aa-Ab)-B-C-D. Most of the presented systems are adequately bright and showing deep enough eclipses, hence we call for new ground-based observations for these extremely interesting multiples. Owing to this motivation our catalog contains besides the ephemerides for both pairs also their depths of eclipses and the light curve shapes as extracted from the TESS data. These new ground based observations would be very useful for further derivation of the mutual movement of both pairs on their orbit via detection of the ETVs of both pairs for example.

The study of the development of structures on multiple scales in the cold interstellar medium has experienced rapid expansion in the past decade, on both the observational and the theoretical front. Spectral line studies at (sub-)millimeter wavelengths over a wide range of physical scales have provided unique probes of the kinematics of dense gas in star-forming regions, and have been complemented by extensive, high dynamic range dust continuum surveys of the column density structure of molecular cloud complexes, while dust polarization maps have highlighted the role of magnetic fields. This has been accompanied by increasingly sophisticated numerical simulations including new physics (e.g., supernova driving, cosmic rays, non-ideal magneto-hydrodynamics, radiation pressure) and new techniques such as zoom-in simulations allowing multi-scale studies. Taken together, these new data have emphasized the anisotropic growth of dense structures on all scales, from giant ISM bubbles driven by stellar feedback on $\sim$50--100 pc scales through parsec-scale molecular filaments down to $< 0.1$ pc dense cores and $< 1000$ au protostellar disks. Combining observations and theory, we present a coherent picture for the formation and evolution of these structures and synthesize a comprehensive physical scenario for the initial conditions and early stages of star and disk formation.

We propose a new "helicity-pumping" method for energizing coronal equilibria that contain a magnetic flux rope (MFR) toward an eruption. We achieve this in a sequence of MHD relaxations of small line-tied pulses of magnetic helicity, each of which is simulated by a suitable rescaling of the current-carrying part of the field. The whole procedure is "magnetogram-matching" because it involves no changes to the normal component of the field at the photospheric boundary. The method is illustrated by applying it to an observed force-free configuration whose MFR is modeled with our regularized Biot-Savart law method. We find that, in spite of the bipolar character of the external field, the MFR eruption is sustained by two reconnection processes. The first, which we refer to as breakthrough reconnection, is analogous to breakout reconnection in quadrupolar configurations. It occurs at a quasi-separator inside a current layer that wraps around the erupting MFR and is caused by the photospheric line-tying effect. The second process is the classical tether-cutting reconnection, which develops at the second quasi-separator inside a vertical current layer that is formed below the erupting MFR. Both reconnection processes work in tandem with the magnetic forces of the unstable MFR to propel it through the overlying ambient field, and their interplay may also be relevant for the thermal processes occurring in the plasma of solar flares. The considered example suggests that our method will be beneficial for both the modeling of observed eruptive events and theoretical studies of eruptions in idealized magnetic configurations.

Neutron stars receive velocity kicks at birth in supernovae. Those formed in electron-capture supernovae from super asymptotic giant branch stars -- the lowest mass stars to end their lives in supernovae -- may receive significantly lower kicks than typical neutron stars. Given that many massive stars are members of wide binaries, this suggests the existence of a population of low-mass ($1.25 < M_\mathrm{psr} / $M$_\odot < 1.3$), wide ($P_\mathrm{orb} \gtrsim 10^{4}$\,day), eccentric ($e \sim 0.7$), unrecycled ($P_\mathrm{spin} \sim 1$\,s) binary pulsars. The formation rate of such binaries is sensitive to the mass range of (effectively) single stars leading to electron capture supernovae, the amount of mass lost prior to the supernova, and the magnitude of any natal kick imparted on the neutron star. We estimate that one such binary pulsar should be observable in the Milky Way for every 10,000 isolated pulsars, assuming that the width of the mass range of single stars leading to electron-capture supernovae is $\lesssim 0.2$\,M$_\odot$, and that neutron stars formed in electron-capture supernovae receive typical kicks less than 10\,km s$^{-1}$. We have searched the catalog of observed binary pulsars, but find no convincing candidates that could be formed through this channel, consistent with this low predicted rate. Future observations with the Square Kilometre Array may detect this rare sub-class of binary pulsar and provide strong constraints on the properties of electron-capture supernovae and their progenitors.

Giant planets acquire gas, ices and rocks during the early formation stages of planetary systems and thus inform us on the formation process itself. Proceeding from inside out, examining the connections between the deep interiors and the observable atmospheres, linking detailed measurements on giant planets in the solar system to the wealth of data on brown dwarfs and giant exoplanets, we aim to provide global constraints on interiors structure and composition for models of the formation of these planets. New developments after the Juno and Cassini missions point to both Jupiter and Saturn having strong compositional gradients and stable regions from the atmosphere to the deep interior. This is also the case of Uranus and Neptune, based on available, limited data on these planets. Giant exoplanets and brown dwarfs provide us with new opportunities to link atmospheric abundances to bulk, interior abundances \rev{and to link these abundances and isotopic ratios to formation scenarios. Analysing the wealth of data becoming available} will require new models accounting for the complexity of the planetary interiors and atmospheres

In the past 15 years, the triaxial Schwarzschild orbit-superposition code by van den Bosch et al. (2008) has been widely applied to study the dynamics of galaxies. Recently, Quenneville et al. (2022) reported a bug in the orbit calculation of this code, specifically in the mirroring procedure that is used to speed up the computation. We have fixed the incorrect mirroring in DYNAMITE, which is the publicly-released successor of the triaxial Schwarzschild code by van den Bosch et al. (2008). In this study, we provide a thorough quantification of how this bug has affected the results of dynamical analyses performed with this code. We compare results obtained with the original and corrected versions of DYNAMITE, and discuss the differences in the phase-space distribution of a single orbit and in the global stellar orbit distribution, in the mass estimate of the central black hole in the highly triaxial galaxy PGC 46832, and in the measurement of intrinsic shape and enclosed mass for more than 50 galaxies. Focusing on the typical scientific applications of a Schwarzschild triaxial code, in all our tests we find that differences are negligible with respect to the statistical and systematic uncertainties. We conclude that previous results with the van den Bosch et al. (2008) triaxial Schwarzschild code are not significantly affected by the incorrect mirroring.

Understanding the explosion mechanism of type Ia supernova is among the most challenging issues in astrophysics. Accretion of matter on a carbon-oxygen white dwarf from a companion star is one of the most important keys in this regard. Our aim is to study the effects of WD composition on various parameters during the accretion of helium rich matter at a slow rate. We have used the computer simulation code Modules for Experiments in Stellar Astrophysics (MESA) to understand the variations in the properties such as specific heat (\textit{$C_P$}) and degeneracy parameter (\textit{$\eta$}). The profile of specific heat shows a discontinuity and that of the degeneracy parameter shows a dip near the ignition region. As expected, the size of WD decreases and \textit{g} increases during the accretion. However, a red-giant-like expansion is observed after the rapid ignition towards the end. Our study explains the reason behind the delay in onset of helium ignition due to the difference in carbon abundance in a CO-WD. We find that white dwarfs of the lower abundance of carbon accrete slightly longer before the onset of helium ignition.

Simulations suggest that galactic gas disks can be treated as "modified accretion disks", in which coplanar gas spirals into the inner regions of the disk, while being consumed by star-formation and removed by outflows. Observationally there is little evidence for such inflows within the outer disks of galaxies. Taking realistic gas surface densities from observations, the radial velocity of the inflow is only a few km s$^{-1}$ within two scalelengths, but gradually increases with radius to of order 50-100 km s$^{-1}$ at the very outer disk. The effects of this inflow on the 2-d velocity field are examined and shown to be broadly similar to those produced by warped disks, with twist distortions of both the kinematic major and minor axes. By examining the twists of kinematic distortions and the spiral arms for a sample of nearby galaxies, we find that the effect of warps are likely to dominate over the effect of radial inflows. However, we then model mock HI velocity fields that combine warps with inflow velocities of the strength required in the modified accretion disks, and show that these composite systems can actually also be very well matched by pure warped disk models, with $\sim$85\% of the mock galaxies having a mean absolute error in the residuals of less than 10 km s$^{-1}$. This suggests that the signatures of significant radial inflows can easily be "hidden" within the warps and that this may therefore explain the apparent failure to detect radial inflows in galactic disks.

This paper aims to give a brief review of a new concept for the preliminary determination of the evolutionary status of supernova remnants (SNRs). Data obtained by radio observations in continuum are used. There are three different methods underlying the new concept: the first one based on the location of observationally obtained radio surface brightness and corresponding diameter of an SNR on the theoretically derived Sigma-D tracks; the second one based on the forms of radio spectra; and the third one, based on the magnetic field strengths that are estimated through the equipartition (eqp) calculation. Using a combination of these methods, developed over the last two decades by the Belgrade SNR Research Group, we can estimate the evolutionary status of SNRs. This concept helps radio observers to determine preliminarily the stage of the evolution of an SNR observed in radio domain. Additionally, this concept was applied for several SNRs, observed by the Australia Telescope Compact Array (ATCA), and the corresponding results are reviewed here. Moreover, some of the results are revised in this review to reflect the updated recently published Sigma-D and eqp analyses.

The detection of the very early gamma-emission of a Type Ia supernova (SNIa) could provide a deep insight on the explosion mechanism and nature of the progenitor. However this has not been yet possible as a consequence of the expected low luminosity and the distance at which all the events have occurred up to now. A SNIa occurring in our Galaxy could provide a unique opportunity to perform such measurement. The problem is that the optical flux would probably be so attenuated by interstellar extinction that would prevent triggering the observations with gamma-spectrometers at the due time. In this paper we analyse the possibility of using the anticoincidence system (ACS) of the spectrometer SPI on board of the INTEGRAL space observatory for detecting the early gamma-ray emission of a SNIa as a function of the explosion model and distance as well as of pointing direction. Our results suggest that such detection is possible at about 6 - 12 days after the explosion and, at the same time, we can discard missing any hidden explosion during the lifetime of INTEGRAL.

We report the phase-connected timing ephemeris, polarization pulse profiles, Faraday rotation measurements, and Rotating-Vector-Model (RVM) fitting results of twelve millisecond pulsars (MSPs) discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal radio Astronomy FAST survey (CRAFTS). The timing campaigns were carried out with FAST and Arecibo over three years. Eleven of the twelve pulsars are in neutron star - white dwarf binary systems, with orbital periods between 2.4 and 100 d. Ten of them have spin periods, companion masses, and orbital eccentricities that are consistent with the theoretical expectations for MSP - Helium white dwarf (He WD) systems. The last binary pulsar (PSR J1912$-$0952) has a significantly smaller spin frequency and a smaller companion mass, the latter could be caused by a low orbital inclination for the system. Its orbital period of 29 days is well within the range of orbital periods where some MSP - He WD systems have shown anomalous eccentricities, however, the eccentricity of PSR J1912$-$0952 is typical of what one finds for the remaining MSP - He WD systems.

Numerical models of Photodissociation Regions (PDRs) are an essential tool to quantitatively understand observations of massive star forming regions through simulations. Few mature PDR models are available and the Cologne KOSMA-$\tau$ PDR model is the only sophisticated model that uses a spherical cloud geometry thereby allowing us to simulate clumpy PDRs. We present the current status of the code as reference for modelers and for observers that plan to apply KOSMA-$\tau$ to interpret their data. For the numerical solution of the chemical problem we present a superior Newton-Raphson stepping algorithm and discuss strategies to numerically stabilize the problem and speed up the iterations. The chemistry in KOSMA-$\tau$ is upgraded to include the full surface chemistry in an up-to-date formulation and we discuss a novel computation of branching ratios in chemical desorption reactions. The high dust temperature in PDRs leads to a selective freeze-out of oxygen-bearing ice species due to their higher condensation temperatures and we study changes in the ice mantle structures depending on the PDR parameters, in particular the impinging UV field. Selective freeze-out can produce enhanced C abundances and higher gas temperatures resulting in a fine-structure line emission of atomic carbon [C] enhanced by up to 50% if surface reactions are considered. We show how recent ALMA observations of HCO$^+$ emission in the Orion Bar with high spatial resolution on the scale of individual clumps can be interpreted in the context of non-stationary, clumpy PDR ensembles. Additionally, we introduce WL-PDR, a simple plane-parallel PDR model written in Mathematica to act as numerical testing environment of PDR modeling aspects.

We investigated the applicability of the weak-field approximation (WFA) for retrieving the depth-dependent line-of-sight (LOS) magnetic field from the spectral region containing the Mg I $b_2$ spectral line and two photospheric Ti I and Fe I lines. We constructed and used a 12-level model for Mg I atom that realistically reproduces the $b_2$ line profile of the mean quiet Sun. We tested the applicability of the WFA to the spectra computed from the FAL C atmospheric model with ad hoc added different magnetic and velocity fields. Then, we extended the analysis to the spectra computed from two 3D magneto-hydrodynamic (MHD) MURaM simulations of the solar atmosphere. The first MHD cube is used to estimate the Stokes V formation heights of each spectral line. These heights correspond to optical depths at which the standard deviation of the difference between the WFA-inferred magnetic field and the magnetic field in the MHD cube is minimal. The estimated formation heights are verified using the second MHD cube. The LOS magnetic field retrieved by the WFA is reliable for the magnetic field strength up to 1.4 kG even when moderate velocity gradients are present. The exception is the Fe I line, for which we found a strong discrepancy in the inferred magnetic fields because of the line blend. We estimated the Stokes $V$ formation heights of each spectral line to be: $\log\tau_\mathrm{Fe}=-2.6$, $\log\tau_\mathrm{Mg}=-3.3$, and $\log\tau_\mathrm{Ti}=-1.8$. We were able to estimate the LOS magnetic field from the MURaM cube at these heights with the uncertainty of 150 G for the Fe I and Ti I lines and only 40 G for the Mg I $b_2$ line. Using the WFA we can quickly get a reliable estimate of the structure of the LOS magnetic field in the observed region. The Mg I $b_2$ line profile calculated from the quiet Sun MURaM simulation agrees very well with the observed mean spectrum of the quiet Sun.

Stellar convection is a non-local process responsible for the transport of heat and chemical species. It can lead to enhanced mixing through convective overshooting and excitation of internal gravity waves (IGWs) at convective boundaries. The relationship between these processes is still not well understood and requires global hydrodynamic simulations to capture the important large-scale dynamics. The steep stratification in stellar interiors suggests that the radial extent of such simulations can affect the convection dynamics, the IGWs in the stably stratified radiative zone, and the depth of the overshooting layer. We investigate these effects using two-dimensional global simulations performed with the fully compressible stellar hydrodynamics code MUSIC. We compare eight different radial truncations of the same solar-like stellar model evolved over approximately 400 convective turnover times. We find that the location of the inner boundary has an insignificant effect on the convection dynamics, the convective overshooting and the travelling IGWs. We relate this to the background conditions at the lower convective boundary which are unaffected by the truncation, as long as a significantly deep radiative layer is included in the simulation domain. However, we find that extending the outer boundary by only a few percent of the stellar radius significantly increases the velocity and temperature perturbations in the convection zone, the overshooting depth, the power and the spectral slope of the IGWs. The effect is related to the background conditions at the outer boundary, which are determined in essence by the hydrostatic stratification and the given luminosity.

We present Diffstar, a smooth parametric model for the in-situ star formation history (SFH) of galaxies. Diffstar is distinct from conventional SFH models that are used to interpret the spectral energy distribution (SED) of an observed galaxy, because our model is parametrized directly in terms of basic features of galaxy formation physics. The Diffstar model assumes that star formation is fueled by the accretion of gas into the dark matter halo of the galaxy, and at the foundation of Diffstar is a parametric model for halo mass assembly, Diffmah. We include parametrized ingredients for the fraction of accreted gas that is eventually transformed into stars, $\epsilon_{\rm ms},$ and for the timescale over which this transformation occurs, $\tau_{\rm cons};$ some galaxies in Diffstar experience a quenching event at time $t_{\rm q},$ and may subsequently experience rejuvenated star formation. We fit the SFHs of galaxies predicted by the IllustrisTNG (TNG) and UniverseMachine (UM) simulations with the Diffstar parameterization, and show that our model is sufficiently flexible to describe the average stellar mass histories of galaxies in both simulations with an accuracy of $\sim0.1$ dex across most of cosmic time. We use Diffstar to compare TNG to UM in common physical terms, finding that: (i) star formation in UM is less efficient and burstier relative to TNG; (ii) galaxies in UM have longer gas consumption timescales, $\tau_{\rm cons}$, relative to TNG; (iii) rejuvenated star formation is ubiquitous in UM, whereas quenched TNG galaxies rarely experience sustained rejuvenation; and (iv) in both simulations, the distributions of $\epsilon_{\rm ms}$, $\tau_{\rm cons}$, and $t_{\rm q}$ share a common characteristic dependence upon halo mass, and present significant correlations with halo assembly history. [Abridged]

During the formation of our solar system, a large number of planetesimals were ejected into interstellar space by gravitational encounters with the planets. Debris disks observations and numerical simulations indicate that many other planetary systems, now known to be quite common, would have undergone a similar dynamical clearing process. It is therefore expected that the galaxy should be teeming with expelled planetesimals, largely unaltered since their ejection. This is why astronomers were perplexed that none had been detected passing through the solar system. Then, in 2017, the discovery of1I/'Oumuamua transformed the situation from puzzlement to bewilderment. Its brief visit and limited observations left important questions about its nature and origin unanswered and raised the possibility that 1I/'Oumuamua could be a never-seen-before intermediate product of planet formation. If so, this could open a new observational window to study the primordial building blocks of planets, setting unprecedented constraints on planet formation models. Two years later 2I/Borisov was discovered, with an unquestionable cometary composition, confirming that a population of icy interstellar planetesimals exists. These objects have remained largely unchanged since their ejection, like time capsules of their planetary system most distant past. Interstellar planetesimals could potentially be trapped into star and planet formation environments, acting as seeds for planet formation, helping overcome the meter-size barrier that challenges the growth of cm-sized pebbles into km-sized objects. Interstellar planetesimals play a pivotal role in our understanding of planetary system formation and evolution and point to the possibility that one day, we will be able to hold a fragment from another world in our hand.

Solar nanoflares are small eruptive events releasing magnetic energy in the quiet corona. If nanoflares follow the same physics as their larger counterparts, they should emit hard X-rays (HXRs) but with a rather faint intensity. A copious and continuous presence of nanoflares would deliver enormous amounts of energy into the solar corona, possibly accounting for its high temperatures. To date, there has not been any direct observation of such sustained and persistent HXRs from the quiescent Sun. However, Hannah et al. in 2010 constrained the quiet Sun HXR emission using almost 12 days of quiescent solar-off-pointing observations by RHESSI. These observations set upper limits at $3.4\times 10^{-2}$ photons$^{-1}$ s$^{-1}$ cm$^{-2}$ keV$^{-1}$ and $9.5\times 10^{-4}$ photons$^{-1}$ s$^{-1}$ cm$^{-2}$ keV$^{-1}$ for the 3-6 keV and 6-12 keV energy ranges, respectively. Observing feeble HXRs is challenging because it demands high sensitivity and dynamic range instruments in HXRs. The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket experiment excels in these two attributes. Particularly, FOXSI completed its third successful flight (FOXSI-3) on September 7th, 2018. During FOXSI-3's flight, the Sun exhibited a fairly quiet configuration, displaying only one aged non-flaring active region. Using the entire $\sim$6.5 minutes of FOXSI-3 data, we constrained the quiet Sun emission in HXRs. We found $2\sigma$ upper limits in the order of $\sim 10^{-3}$ photons$^{-1}$ s$^{-1}$ cm$^{-2}$ keV$^{-1}$ for the 5-10 keV energy range. FOXSI-3's upper limit is consistent with what was reported by Hannah et al., 2010, but FOXSI-3 achieved this result using $\sim$1/2640 less time than RHESSI. A possible future spacecraft using FOXSI's concept would allow enough observation time to constrain the current HXR quiet Sun limits further or perhaps even make direct detections.

Using the latest observational data from Planck-CMB and its combination with the pre-reconstructed full-shape (FS) galaxy power spectrum measurements from the BOSS DR12 sample and eBOSS LRG DR16 sample, we report the observational constraints on the cosmic neutrino properties given by the extended $\Lambda$CDM scenario: $\Lambda$CDM + $N_{\rm eff}$ + $\sum m_{\nu}$ + $c^2_{\rm eff}$ + $c^2_{\rm vis}$ + $\xi_{\nu}$, and its particular case $\Lambda$CDM + $c^2_{\rm eff}$ + $c^2_{\rm vis}$ + $\xi_{\nu}$, where $N_{\rm eff}$, $\sum m_{\nu}$, $c^2_{\rm eff}$, $c^2_{\rm vis}$, $\xi_{\nu}$ are the effective number of species, the total neutrino mass, the sound speed in the neutrinos rest frame, the viscosity parameter and the degeneracy parameter quantifying a cosmological leptonic asymmetry, respectively. We observe that the combination of FS power spectrum measurements with the CMB data significantly improves the full parametric space of the models compared to the CMB data alone case. We find no evidence for neutrinos properties other than the ones predicted by the standard cosmological theory. Our most robust observational constraints are given by CMB + BOSS analysis. For the generalized extended $\Lambda$CDM scenario, we find $c^2_{\rm eff}=0.3300\pm 0.0083$, $c^2_{\rm vis}=0.283\pm 0.047$, $\xi_{\nu} < 0.26$, $N_{\rm eff}=2.98^{+0.20}_{-0.27}$ at 68\% CL, with $\sum m_{\nu} < 0.117$ eV at 95\% CL while for the aforementioned particular case, $\xi_{\nu} < 0.06$ at 68\% CL. These are the strongest limits ever reported for these extended $\Lambda$CDM scenarios.

We report the first detection of deuterated water (HDO) toward an extragalactic hot core. The HDO 2$_{11}$-2$_{12}$ line has been detected toward hot cores N105-2A and 2B in the N105 star-forming region in the low-metallicity Large Magellanic Cloud (LMC) dwarf galaxy with the Atacama Large Millimeter/submillimeter Array (ALMA). We have compared the HDO line luminosity ($L_{\rm HDO}$) measured toward the LMC hot cores to those observed toward a sample of seventeen Galactic hot cores covering three orders of magnitude in $L_{\rm HDO}$, four orders of magnitude in bolometric luminosity ($L_{\rm bol}$), and a wide range of Galactocentric distances (thus metallicities). The observed values of $L_{\rm HDO}$ for the LMC hot cores fit very well into the $L_{\rm HDO}$ trends with $L_{\rm bol}$ and metallicity observed toward the Galactic hot cores. We have found that $L_{\rm HDO}$ seems to be largely dependent on the source luminosity, but metallicity also plays a role. We provide a rough estimate of the H$_2$O column density and abundance ranges toward the LMC hot cores by assuming that HDO/H$_2$O toward the LMC hot cores is the same as that observed in the Milky Way; the estimated ranges are systematically lower than Galactic values. The spatial distribution and velocity structure of the HDO emission in N105-2A is consistent with HDO being the product of the low-temperature dust grain chemistry. Our results are in agreement with the astrochemical model predictions that HDO is abundant regardless of the extragalactic environment and should be detectable with ALMA in external galaxies.

We compute the expected strain power spectrum and energy density parameter of the stochastic gravitational wave background (SGWB) created by a network of long cosmic strings evolving during the whole cosmic history. As opposed to other studies, the contribution of cosmic string loops is discarded and our result provides a robust lower bound of the expected signal that is applicable to most string models. Our approach uses Nambu-Goto numerical simulations, running during the radiation, transition and matter eras, in which we compute the two-point unequal-time anisotropic stress correlators. These ones act as source terms in the linearised equations of motion for the tensor modes, that we solve using an exact Green's function integrator. Today, we find that the rescaled strain power spectrum $(k/\mathcal{H}_0)^2 \mathcal{P}_h$ peaks on Hubble scales and exhibits, at large wavenumbers, high frequency oscillations around a plateau of amplitude $100 (GU)^2$. Most of the high frequency power is generated by the long strings present in the matter era, the radiation era contribution being smaller.

We investigated six presolar grains from very primitive regions of the matrix in the unequilibrated ordinary chondrite Semarkona with TEM. These grains include one SiC, one oxide (Mg-Al spinel), and four silicates. Structural and elemental compositional studies of presolar grains located within their meteorite hosts have the potential to provide information on conditions and processes throughout the grains' histories. Our analyses show that the SiC and spinel grains are stoichiometric and well crystallized. In contrast, the majority of the silicate grains are non-stoichiometric and poorly crystallized. These findings are consistent with previous TEM studies of presolar grains from interplanetary dust particles and chondritic meteorites. We interpret the poorly crystalline nature, non-stoichiometry, more Fe- rather than Mg-rich compositions, and/or compositional heterogeneities as features of the formation by condensation under non-equilibrium conditions. Evidence for parent body alteration includes rims with mobile elements (S or Fe) on the SiC grain and one silicate grain. Other features characteristic of secondary processing in the interstellar medium, the solar nebula, and/or on parent bodies, were not observed or are better explained by processes operating in circumstellar envelopes. In general, there was very little overprinting of primary features of the presolar grains by secondary processes (e.g., ion irradiation, grain-grain collisions, thermal metamorphism, aqueous alteration). This finding underlines the need for additional TEM studies of presolar grains located in the primitive matrix regions of Semarkona, to address gaps in our knowledge of presolar grain populations accreted to ordinary chondrites.

Automating classification of galaxy components is important for understanding the formation and evolution of galaxies. Traditionally, only the larger galaxy structures such as the spiral arms, bulge, and disc are classified. Here we use machine learning (ML) pixel-by-pixel classification to automatically classify all galaxy components within digital imagery of massive spiral galaxy UGC 2885. Galaxy components include young stellar population, old stellar population, dust lanes, galaxy center, outer disc, and celestial background. We test three ML models: maximum likelihood classifier (MLC), random forest (RF), and support vector machine (SVM). We use high-resolution Hubble Space Telescope (HST) digital imagery along with textural features derived from HST imagery, band ratios derived from HST imagery, and distance layers. Textural features are typically used in remote sensing studies and are useful for identifying patterns within digital imagery. We run ML classification models with different combinations of HST digital imagery, textural features, band ratios, and distance layers to determine the most useful information for galaxy component classification. Textural features and distance layers are most useful for galaxy component identification, with the SVM and RF models performing the best. The MLC model performs worse overall but has comparable performance to SVM and RF in some circumstances. Overall, the models are best at classifying the most spectrally unique galaxy components including the galaxy center, outer disc, and celestial background. The most confusion occurs between the young stellar population, old stellar population, and dust lanes. We suggest further experimentation with textural features for astronomical research on small-scale galactic structures.

We present a map of the total intrinsic reddening across ~90 deg$^{2}$ of the Large Magellanic Cloud (LMC) derived using optical (ugriz) and near-infrared (IR; YJKs) spectral energy distributions (SEDs) of background galaxies. The reddening map is created from a sample of 222,752 early-type galaxies based on the LEPHARE $\chi^{2}$ minimisation SED-fitting routine. We find excellent agreement between the regions of enhanced intrinsic reddening across the central (4x4 deg$^2$) region of the LMC and the morphology of the low-level pervasive dust emission as traced by far-IR emission. In addition, we are able to distinguish smaller, isolated enhancements that are coincident with known star-forming regions and the clustering of young stars observed in morphology maps. The level of reddening associated with the molecular ridge south of 30 Doradus is, however, smaller than in the literature reddening maps. The reduced number of galaxies detected in this region, due to high extinction and crowding, may bias our results towards lower reddening values. Our map is consistent with maps derived from red clump stars and from the analysis of the star formation history across the LMC. This study represents one of the first large-scale categorisations of extragalactic sources behind the LMC and as such we provide the LEPHARE outputs for our full sample of ~2.5 million sources.

The origin of the quiet Sun magnetism is under debate. Investigating the solar cycle variation observationally in more detail can give us clues about how to resolve the controversies. We investigate the solar cycle variation of the most magnetically quiet regions and their surface gravity oscillation ($f$-) mode integrated energy ($E_f$). We use 12 years of HMI data and apply a stringent selection criteria, based on spatial and temporal quietness, to avoid any influence of active regions (ARs). We develop an automated high-throughput pipeline to go through all available magnetogram data and to compute $E_f$ for the selected quiet regions. We observe a clear solar cycle dependence of the magnetic field strength in the most quiet regions containing several supergranular cells. For patch sizes smaller than a supergranular cell, no significant cycle dependence is detected. The $E_f$ at the supergranular scale is not constant over time. During the late ascending phase of Cycle 24 (SC24, 2011-2012), it is roughly constant, but starts diminishing in 2013, as the maximum of SC24 is approached. This trend continues until mid-2017, when hints of strengthening at higher southern latitudes are seen. Slow strengthening continues, stronger at higher latitudes than at the equatorial regions, but $E_f$ never returns back to the values seen in 2011-2012. Also, the strengthening trend continues past the solar minimum, to the years when SC25 is already clearly ascending. Hence the $E_f$ behavior is not in phase with the solar cycle. The anticorrelation of $E_f$ with the solar cycle in gross terms is expected, but the phase shift of several years indicates a connection to the poloidal large-scale magnetic field component rather than the toroidal one. Calibrating AR signals with the QS $E_f$ does not reveal significant enhancement of the $f$-mode prior to AR emergence.

The metallicity dependence of the wide binary fraction (WBF) is critical for studying the formation of wide binaries. While controversial results have been found in recent years. Here we combine the wide binary catalog recognized from Gaia EDR3 and stellar parameters from LAMOST to investigate this topic. Taking bias of the stellar temperature at given separations into account, we find that the relationship between the WBF and metallicity depends on temperature for the thin-disk at s > 200 AU. It changes from negative to positive as the temperature increases from 4000 K to 7500 K. This temperature/mass dependence is not seen for the thick-disk. Besides, the general tendency between the WBF and metallicity varies with the separation, consistent with previous results. It shows anti-correlation at small separations, s < 200 AU for the thin-disk and s < 600 AU for the thick-disk. Then it becomes an "arcuate" shape at larger separations (hundreds to thousands of AU), peaking at [Fe/H] ~ 0.1 for the thin-disk and [Fe/H] ~ -0.5 for the thick disk. Finally it becomes roughly flat for the thin-disk at 1000 < s < 10000 AU. Our work provides new observational evidences for theoretical studies on binary formation and evolution.

The developments in modeling of instrumental background for MeV telescopes such as INTEGRAL/SPI and Fermi/GBM, as well as new gamma-ray projects such as the accepted COSI and the proposed e-ASTROGAM and AMEGO missions, suggest the potential of observing elusive transients. This allows testing the stellar explosion mechanisms and their corresponding nucleosynthesis through short-lived radioactive isotopes with improved sensitivity and accuracy. This raises for the need of a radiative transfer code which may efficiently explore different types of astrophysical $\gamma$-ray sources and their dependence on model parameters and input physics. In view of this, we present our new Monte-Carlo Radiative Transfer code in Python. The code synthesizes the spectra and light curves suitable for modeling supernova ejecta. We test the code extensively for reproducing results consistent with analytic models, in particular for scenarios including C+O novae, O+Ne novae, Type Ia and core-collapse supernovae. We also compare our results with similar models in the literature and discuss how our code depends on selected input physics and setting.

We present a detailed study of the evolution of the Galactic black hole transient GRS 1716-249 during its 2016-2017 outburst at optical (Las Cumbres Observatory), mid-infrared (Very Large Telescope), near-infrared (Rapid Eye Mount telescope), and ultraviolet (the Neil Gehrels Swift Observatory Ultraviolet/Optical Telescope) wavelengths, along with archival radio and X-ray data. We show that the optical/near-infrared and UV emission of the source mainly originates from a multi-temperature accretion disk, while the mid-infrared and radio emission are dominated by synchrotron emission from a compact jet. The optical/UV flux density is correlated with the X-ray emission when the source is in the hard state, consistent with an X-ray irradiated accretion disk with an additional contribution from the viscous disk during the outburst fade. We also report the long-term optical light curve of the source and find that the quiescent i-band magnitude is 21.39$\pm$0.15 mag. Furthermore, we discuss how previous estimates of the system parameters of the source are based on various incorrect assumptions, and so are likely to be inaccurate. By comparing our GRS 1716-249 dataset to those of other outbursting black hole X-ray binaries, we find that while GRS 1716-249 shows similar X-ray behaviour, it is noticeably optically fainter, if the literature distance of 2.4 kpc is adopted. Using several lines of reasoning, we argue that the source distance is further than previously assumed in the literature, likely within 4-17 kpc, with a most likely range of $\sim$4-8 kpc.

We study the Peccei-Quinn (PQ) symmetry of the sterile right-handed neutrino sector and the gauge symmetries of the Standard Model. Due to four-fermion interactions, spontaneous breaking of these symmetries at the electroweak scale generates top-quark Dirac mass and sterile-neutrino Majorana mass. The top quark channel yields massive Higgs, $W^\pm$ and $Z^0$ bosons. The sterile neutrino channel yields the heaviest sterile neutrino Majorana mass, sterile Nambu-Goldstone axion (or majoron) and massive scalar $\chi$boson. Four-fermion operators effectively induce their tiny couplings to SM particles. We show that a sterile QCD axion is the PQ solution to the strong CP problem. The lightest and heaviest sterile neutrinos ($m_N^e\sim 10^2$ keV and $m_N^\tau\sim 10^2$ GeV), a sterile QCD axion ($m_a< 10^{-8}$ eV, $g_{a\gamma}< 10^{-13} {\rm GeV}^{-1}$) and a Higgs-like $\chi$boson ($m_\chi\sim 10^2$ GeV) can be dark matter particle candidates, for the constraints of their tiny couplings and long lifetimes inferred from the $W$-boson decay width, Xenon1T and precision fine-structure-constant experiments. The axion and $\chi$boson couplings to SM particles are below the values reached by current laboratory experiments and astrophysical observations for directly or indirectly detecting dark matter particles.

Bosonic field theories with non-linear interactions alongside gravity, generally admit bound states known as solitons. Depending upon the spin nature of the field, they can even carry macroscopic intrinsic spin polarization. Focusing on the Higgsed SU($2$) Yang-Mills theory, we describe polarized solitons in non-Abelian theories with a heavy Higgs, which we refer to as `Yang-Mills stars'. Owing to both kinds of self-interactions; repulsive ones arising due to the Yang-Mills structure, while attractive ones arising due to the Higgs exchange; we can have a diverse zoo of solitons. Depending upon various parameters of the theory such as the mass of the Yang-Mills vector fields $m$, mass of the dark Higgs field $M_{\varphi}$, and the gauge coupling constant $g$, these objects can be astrophysically large with varying size and mass, and carry large intrinsic spin and/or isospin giving rise to interesting phenomenological implications. Even for vector mass as large as $m \simeq 10$ eV, we can accommodate gauge couplings $g \lesssim 10^{-4}-10^{-5}$, still evading Bullet cluster constraints. For these parameters, we get astrophysically long lived solitons having radii as large as $r_{s} \sim 10^{5}\,R_{\odot}$ and masses $M_{s} \sim 10 M_{\odot}$, carrying $M_{s}/m \sim 10^{66}$ amounts of intrinsic spin/isospin polarization.

We propose a novel way of probing high scale Dirac leptogenesis, a viable alternative to canonical leptogenesis scenario where the total lepton number is conserved, keeping light standard model (SM) neutrinos purely Dirac. The simplest possible seesaw mechanism for generating light Dirac neutrinos involve heavy singlet Dirac fermions and a singlet scalar. In addition to unbroken global lepton number, a discrete $Z_2$ symmetry is imposed to forbid direct coupling between right and left chiral parts of light Dirac neutrino. Generating light Dirac neutrino mass requires the singlet scalar to acquire a vacuum expectation value (VEV) that also breaks the $Z_2$ symmetry, leading to formation of domain walls in the early universe. These walls, if made unstable by introducing a soft $Z_2$ breaking term, generate gravitational waves (GW) with a spectrum characterized by the wall tension or the singlet VEV, and the soft symmetry breaking scale. The scale of leptogenesis depends upon the $Z_2$-breaking singlet VEV which is also responsible for the tension of the domain wall, affecting the amplitude of GW produced from the collapsing walls. We find that most of the near future GW observatories will be able to probe Dirac leptogenesis scale all the way upto $10^{11}$ GeV.

Post-inflationary reheating is a widely discussed mechanism for non-thermal production of dark matter (DM). In this scenario the momentum distribution of the produced DM particles is usually taken to be the one obtained at reheating, red-shifted at later times due to the expansion of the Universe. However, since in such a scenario both the DM and the standard model (SM) fields couple to the inflaton, the DM particles necessarily undergo self-scatterings, as well as elastic and inelastic scattering reactions with the SM bath, all of which proceed through $s-$channel or $t-$channel inflaton exchange. We compute the momentum distribution of the DM particles including the effect of these scatterings, and find that the distributions can be significantly altered, even though DM remains non-thermal throughout the cosmological evolution. We observe that if the inflaton dominantly couples to the SM Higgs boson through a renormalizable interaction, then reheating temperatures and inflaton masses at the TeV scale lead to a large effect from the scattering processes, with the DM-inflaton coupling constrained by the DM density. The scattering effects are found to be sensitive to the duration of the reheating process -- larger the duration, more momentum modes are filled at reheating, leading to an enhanced scattering probability. We also obtain the free-streaming length of such DM using the resulting non-thermal momentum distribution, which can be used to estimate the implications of the Lyman-$\alpha$ constraints on the DM mass. It is observed that in the scenarios considered, including the scattering effects can reduce the DM average velocity at matter-radiation equality, and its free-streaming length, by upto a factor of $40$, thereby making the constraints on light DM produced in inflaton decay significantly weaker.

We introduce a family of equations of state (EoS) for hybrid neutron star (NS) matter that is obtained by a two-zone parabolic interpolation between a soft hadronic EoS at low densities and a stiff quark matter EoS with color superconductivity at high densities within a finite region of baryonic chemical potentials $\mu_B^h < \mu_B < \mu_B^q$. We consider two scenarios corresponding to a cross-over and a strong first-order transition between quark and hadron phases considered at finite and zero temperatures. This allows us to analyze the effects of finite entropy on the EoS and mass-radius relation of NS. We demonstrate that the formation of a color superconducting state of quark matter drives the evolution of matter in supernovae explosions under the condition of entropy conservation to higher temperatures than in the case of deconfinement to normal quark matter. Within the presented hybrid EoS scenario, regions of the QCD phase diagram may be accessible to supernovae and NS mergers that can be reached also in terrestrial experiments with relativistic heavy ion collisions.

In modified gravity theories, such as the Brans-Dicke theory, the background evolution of the Universe and the perturbation around it are different from that in general relativity. Therefore, the gravitational waveforms used to study standard sirens in these theories should be modified. The modifications of the waveforms can be classified into two categories: wave generation effects and wave propagation effects. Hitherto, the waveforms used to study standard sirens in the modified gravity theories incorporate only the wave propagation effects and ignore the wave generation effects. In this work, we construct the consistent waveforms for standard sirens in the Brans-Dicke theory. The wave generation effects include the emission of the scalar breathing polarization $h_b$ and the corrections to the tensor polarizations $h_+$ and $h_\times$; the wave propagation effect is the modification of the luminosity distance for the gravitational waveforms. Using the consistent waveforms, we analyze the parameter estimation biases due to the ignorance of the wave generation effects. We find that the ratio of the theoretical bias to the statistical error of the redshifted chirp mass is two orders of magnitude larger than that of the source distance.

We discuss a way in which the geometric scalar field in a Brans-Dicke theory can evade local astronomical tests and act as a driver of the late-time cosmic acceleration. This requires a self-interaction of the Brans-Dicke scalar as well as an interaction with ordinary matter. The scalar field in this construct acquires a density-dependent effective mass much like a Chameleon field. We discuss the viability of this setup in the context of the Equivalence Principle, Fifth Force, and Solar System tests. The cosmological consistency is adjudged in comparison with observational data from recalibrated light curves of type Ia supernova (JLA), the Hubble parameter measurements (OHD), and the Baryon Acoustic Oscillation (BAO). We deduct that the astrophysical constraints indeed favor the existence of a mild scalar-matter interaction in the Jordan Frame.

Density filamentation has been observed in many beam-plasma simulations and experiments. Because current filamentation is a pure transverse mode, charge density filamentation cannot be produced directly by the current filamentation process. To explain this phenomenon, several mechanisms are proposed such as the coupling of the Weibel instability to the two-stream instability, coupling to the Langmuir wave, differences in thermal velocities between the beam and return currents, the magnetic pressure gradient force, etc. In this paper, it is shown that the gradient of the Lorentz factor can, in fact, represent the nonlinear behavior of a plasma fluid and further that the nonuniform Lorentz factor distribution can give rise to electrostatic fields and density filaments. Simulation results together with theoretical analyses are presented.

Variations in sea-level, based on tide gauge data (GSLTG) and on combining tide gauges and satellite data (GSLl) are subjected to singular spectrum analysis (SSA), to determine their trends and periodic or quasi-periodic components. GLSTG increases by 90 mm from 1860 to 2020, a contribution of 0.56 mm/yr to the mean rise rate. Annual to multi-decadal periods of ~90/80, 60, 30, 20, 10/11, and 4/5 years are found in both GSLTG and GSLl. These periods are commensurable periods of the Jovian planets, combinations of the periods of Neptune (165 yr), Uranus (84 yr), Saturn (29 yr) and Jupiter (12 yr). These same periods are encountered in sea-level changes, motion of the rotation pole RP and evolution of global pressure GP, suggesting physical links. The first SSA components comprise most of the signal variance: 95% for GSLTG, 89% for GSLI, 98% for GP, 75% for RP. Laplace derived the Liouville-Euler equations that govern the rotation and translation of the rotation axis of any celestial body. He emphasized that one must consider the orbital kinetic moments of all planets in addition to gravitational attractions and concluded that the Earth's rotation axis should undergo motions that carry the combinations of periods of the Sun, Moon and planets. Almost all the periods found in the SSA components of sea-level (GSLl and GSLTG), global pressure (GP) and polar motion (RP), of their modulations and their derivatives can be associated with the Jovian planets. It would be of interest to search for data series with longer time spans, that could allow one to test whether the trends themselves could be segments of components with still longer periodicities (e.g. 175 yr Jose cycle).

Seismic noise poses challenges for gravitational wave detection. Effective vibration isolation and methods to subtract unsheildable Newtonian Noise are examples. Seismic arrays offer one way to deal with these issues assuming seismic coherency. In this paper we find that wind induced seismic noise is incoherent and will dramatically reduce the projected low frequency sensitivity of future gravitational wave detectors. To quantify this, we measure the coherence length of wind induced seismic noise from 0.06--20~Hz in three distinct locations: close to a building, among tall trees and in shrubs. We show that wind induced seismic noise is ubiquitous and reduces the coherence lengths form several hundred meters to 2--40~m for 0.06--0.1~Hz, from $>$60~m to 3--16~m for 1.5--2.5~Hz and from $>$35~m to 1--16~m around 16.6 Hz frequency bands in the study area. This leads to significant loss of velocity and angular resolution of the array for primary microseism, 5 times worse Newtonian Noise cancellation by wiener filtering at 2~Hz, while it does not pose additional challenge for Newtonian Noise cancellation between 10--20~Hz.

We study the motion of test particles in the gravitational field of a Schwarzschild black hole surrounded by a spherical dark matter cloud with non-zero tangential pressure and compute the luminosity of the accretion disk. The presence of non vanishing tangential pressures allows to mimic the dark matter's angular momentum while still considering a static model, which simplifies the mathematical framework. We compare the numerical results about the influence of dark matter on the luminosity of accretion disks around static supermassive black holes with the previously studied cases of isotropic and anisotropic pressures. We show that the flux and luminosity of the accretion disk in the presence of dark matter are different from the case of a Schwarzschild black hole in vacuum and highlight the impact of the presence of tangential pressures.

The micro-canonical phase-space volume for the three-body problem is an elementary quantity of intrinsic interest, and within the flux-based statistical theory, it sets the scale of the disintegration time. While the bare phase-volume diverges, we show that a regularized version can be defined by subtracting a reference phase-volume, which is associated with hierarchical configurations. The reference quantity, also known as a counter-term, can be chosen from a 1-parameter class. The regularized phase-volume of a given (negative) total energy, $\bar\sigma(E)$, is evaluated. First, it is reduced to a function of the masses only, which is sensitive to the choice of a regularization scheme only through an additive constant. Then, analytic integration is used to reduce the integration to a sphere, known as shape sphere. Finally, the remaining integral is evaluated numerically, and presented by a contour plot in parameter space. Regularized phase-volumes are presented for both the planar three-body system and the full 3d system. In the test mass limit, the regularized phase-volume is found to become negative, thereby signalling the breakdown of the non-hierarchical statistical theory. This work opens the road to the evaluation of $\bar\sigma(E,L)$, where $L$ is the total angular momentum, and it turn, to comparison with simulation determined disintegration times.

We investigate in-medium polarization effects of the fermion and antifermion pairs at finite temperature and density in strong magnetic fields within the lowest Landau level approximation. Inspecting the integral representation of the polarization tensor by analytic and numerical methods, we provide both the real and imaginary parts of the polarization tensor obtained after delicate interplay between the vacuum and medium contributions essentially due to the Pauli-blocking effect. Especially, we provide a complete analytic form of the polarization tensor at zero temperature and finite density that exhibits an exact cancellation and associated relocation of the singular threshold behaviors for a single photon decay to a fermion and antifermion pair. As a physical application of the in-medium polarization tensor, we discuss the magneto-birefringence that is polarization-dependent dispersion relations of photons induced by the strong magnetic fields.

This paper presents high-order Runge-Kutta (RK) discontinuous Galerkin methods for the Euler-Poisson equations in spherical symmetry. The scheme can preserve a general polytropic equilibrium state and achieve total energy conservation up to machine precision with carefully designed spatial and temporal discretizations. To achieve the well-balanced property, the numerical solutions are decomposed into equilibrium and fluctuation components which are treated differently in the source term approximation. One non-trivial challenge encountered in the procedure is the complexity of the equilibrium state, which is governed by the Lane-Emden equation. For total energy conservation, we present second- and third-order RK time discretization, where different source term approximations are introduced in each stage of the RK method to ensure the conservation of total energy. A carefully designed slope limiter for spherical symmetry is also introduced to eliminate oscillations near discontinuities while maintaining the well-balanced and total-energy-conserving properties. Extensive numerical examples -- including a toy model of stellar core-collapse with a phenomenological equation of state that results in core-bounce and shock formation -- are provided to demonstrate the desired properties of the proposed methods, including the well-balanced property, high-order accuracy, shock capturing capability, and total energy conservation.