Papers for Monday, Mar 08 2021

The exact result for non-relativistic quadrupole bremsstrahlung in a Coulomb field was established only recently in Pradler & Semmelrock (2020). It requires the evaluation and integration of hypergeometric functions across a wide range of parameters and arguments, which, in practice, is unfeasible. Here we provide a highly accurate tabulation of the Gaunt factor for quadrupole radiation, its thermal average in a Maxwellian plasma, and the associated cooling function over the entire kinematically relevant range. In addition, we provide a simple approximate formula for the emission cross section which works to within a few percent accuracy for all practical purposes. The results can be applied to the scattering of electrons with themselves, for which quadrupole radiation is the dominant process.

Several lines of evidence suggest the Milky Way underwent a major merger at z~2 with a galaxy known as Gaia-Sausage-Enceladus (GSE). Here we use H3 Survey data to argue that GSE entered the Galaxy on a retrograde orbit based on a population of highly retrograde stars with chemistry similar to the largely radial GSE debris. We present the first tailored, high-resolution N-body simulations of the merger. From a grid of ~500 simulations we find a GSE with $M_{*}=5\times10^{8}\ M_{\odot}, M_{\rm{DM}}=2\times10^{11} M_{\odot}$ (a 2.5:1 total mass merger) best matches the H3 data. This simulation shows the retrograde GSE stars are stripped from its outer disk early in the merger before the orbit loses significant angular momentum. Despite being selected purely on angular momenta and radial distributions, this simulation reproduces and explains the following empirical phenomena: (i) the elongated, triaxial shape of the inner halo (axis ratios $10:7.9:4.5$), whose major axis is at ~35{\deg} to the plane and connects GSE's apocenters, (ii) the Hercules-Aquila Cloud & the Virgo Overdensity, which arise due to apocenter pile-up, (iii) the 2 Gyr lag between the quenching of GSE and the truncation of the age distribution of the in-situ halo, which tracks the 2 Gyr gap between the first and final GSE pericenters. We make the following predictions: (i) the inner halo has a "double-break" density profile with breaks at both ~15-18 kpc and 30 kpc, coincident with the GSE apocenters, (ii) the outer halo has retrograde streams containing ~10% of GSE stars awaiting discovery at >30 kpc. The retrograde (radial) GSE debris originates from its outer (inner) disk -- exploiting this trend we reconstruct the stellar metallicity gradient of GSE ($-0.04\pm0.01$ dex $r_{\rm{50}}^{-1}$). These simulations imply GSE delivered ~20% of the Milky Way's present-day dark matter and ~50% of its stellar halo. (ABRIDGED)

The period in which hydrogen in the intergalactic medium (IGM) is ionized, known as the Epoch of Reionization (EoR) is still poorly understood. The timing and duration of the EoR is expected to be governed by the underlying astrophysics. Furthermore, most models of reionization predict a correlation between the density and ionization field. Here we consider using the mean dispersion measure (DM) of high redshift Fast Radio Bursts (FRBs) as a probe of the underlying astrophysics and morphology of the EoR. To do this, we forecast observational scenarios by building mock data sets of non-repeating FRBs between redshifts $8\leq z \leq 10$. It is assumed that all FRBs have accompanying spectroscopic redshift measurements. We find that samples of 100 high redshift FRBs, in the above mentioned narrow redshift range, can rule out uncorrelated reionization at $68\%$ credibility, while larger samples, $\geq 10^4$ FRBs, can rule out uncorrelated reionization at $95\%$ credibility. We also find 100 high redshift FRBs can rule out scenarios where the Universe is entirely neutral at $z = 10$ with $68\%$ credibility. Further with $\geq 10^5$ FRBs, we can constrain the duration $\Delta z$ of reionization (duration between mean ionized fraction 0.25 to 0.75) to $\Delta z = 2.0^{+0.5}_{-0.4}$, and the midpoint of reionization to $z = 7.8^{+0.4}_{-0.2}$ at $95\%$ credibility.

We present constraints on the dust continuum flux and inferred gas content of a gravitationally lensed massive quiescent galaxy at $z$=1.883$\pm$0.001 using AzTEC 1.1mm imaging with the Large Millimeter Telescope. MRG-S0851 appears to be a prototypical massive compact quiescent galaxy, but has evidence that it experienced a centrally concentrated rejuvenation event in the last 100 Myr (see Akhshik et al. 2020). This galaxy is undetected in the AzTEC image but we calculate an upper limit on the millimeter flux and use this to estimate the H$_2$ mass limit via an empirically calibrated relation that assumes a constant molecular gas-to-dust ratio of 150. We constrain the 3$\sigma$ upper limit of the H$_2$ fraction from the dust continuum in MRG-S0851 to be ${M_{H_2}/M_{\star}}$ $\leq$ 6.8%. MRG-S0851 has a low gas fraction limit with a moderately low sSFR owing to the recent rejuvenation episode, which together results in a relatively short depletion time of $<$0.6 Gyr if no further H$_2$ gas is accreted. Empirical and analytical models both predict that we should have detected molecular gas in MRG-S0851, especially given the rejuvenation episode; this suggests that cold gas and/or dust is rapidly depleted in at least some early quiescent galaxies.

The vast quantity of strong galaxy-galaxy gravitational lenses expected by future large-scale surveys necessitates the development of automated methods to efficiently model their mass profiles. For this purpose, we train an approximate Bayesian convolutional neural network (CNN) to predict mass profile parameters and associated uncertainties, and compare its accuracy to that of conventional parametric modelling for a range of increasingly complex lensing systems. These include standard smooth parametric density profiles, hydrodynamical EAGLE galaxies and the inclusion of foreground mass structures, combined with parametric sources and sources extracted from the Hubble Ultra Deep Field. In addition, we also present a method for combining the CNN with traditional parametric density profile fitting where the CNN provides initial priors on the latter's parameters. Across the test sets of images, the CNN achieved errors 19 $\pm$ 22 per cent lower than the traditional method's blind modelling. Using these CNN-predicted parameters as priors for this method to use in an automated fashion instead achieved 27 $\pm$ 11 per cent lower errors over the latter. This was reduced further to 37 $\pm$ 11 per cent when also incorporating the CNN-predicted uncertainties into the priors, helping it to avoid local minima in parameter space, with errors also 17 $\pm$ 21 per cent lower than the CNN by itself. While the CNN is undoubtedly the fastest modelling method, the combination of the two increases the speed of conventional fitting alone by a factor of 1.73 and 1.19 with and without CNN-predicted uncertainties, respectively. This, combined with greatly improved accuracy, highlights the benefits one can obtain through combining neural networks with conventional techniques in order to achieve an efficient automated modelling approach.

Arbitrariness attributed to the zero point constant of the $V$ band bolometric corrections ($BC_V$) and its relation to "bolometric magnitude of a star ought to be brighter than its visual magnitude" and "bolometric corrections must always be negative" was investigated. The falsehood of the second assertion became noticeable to us after IAU 2015 General Assembly Resolution B2, where the zero point constant of bolometric magnitude scale was decided to have a definite value $C_{Bol}(W)= 71.197~425~...$~. Since the zero point constant of the $BC_V$ scale could be written as $C_2=C_{Bol}-C_V$, where $C_V$ is the zero point constant of the visual magnitudes in the basic definition $BC_V=M_{Bol}-M_V=m_{bol}-m_V$, and $C_{Bol}>C_V$, the zero point constant ($C_2$) of the $BC_V$ scale cannot be arbitrary anymore; rather, it must be a definite positive number obtained from the two definite positive numbers. The two conditions $C_2>0$ and $0<BC_V<C_2$ are also sufficient for $L_V<L$, a similar case to negative $BC_V$ numbers, which means that "bolometric corrections are not always negative". In sum it becomes apparent that the first assertion is misleading causing one to understand bolometric corrections must always be negative, which is not necessarily true.

Up to date planet ephemerides are becoming increasingly important as exoplanet science moves from detecting exoplanets to characterising their architectures and atmospheres in depth. In this work ephemerides are updated for 22 Kepler planets and 4 Kepler planet candidates, constituting all Kepler planets and candidates with sufficient signal to noise in the TESS 2min dataset. A purely photometric method is utilised here to allow ephemeris updates for planets even when they do not posses significant radial velocity data. The obtained ephemerides are of very high precision and at least seven years 'fresher' than archival ephemerides. In particular, significantly reduced period uncertainties for Kepler-411d, Kepler-538b and the candidates K00075.01/K00076.01 are reported. O-C diagrams were generated for all objects, with the most interesting ones discussed here. Updated TTV fits of five known multiplanet systems with significant TTVs were also attempted (Kepler-18, Kepler-25, Kepler-51, Kepler-89, and Kepler-396), however these suffered from the comparative scarcity and dimness of these systems in TESS. Despite these difficulties, TESS has once again shown itself to be an incredibly powerful follow-up instrument as well as a planet-finder in its own right. Extension of the methods used in this paper to the 30min-cadence TESS data and TESS extended mission has the potential to yield updated ephemerides of hundreds more systems in the future.

Our understanding of the intergalactic medium at redshifts $z=5$-$6$ has improved considerably in the last few years due to the discovery of quasars with $z>6$ that enable Lyman-$\alpha$ forest studies at these redshifts. A realisation from this has been that hydrogen reionization could end much later than previously thought, so that large "islands" of cold, neutral hydrogen could exist in the IGM at redshifts $z=5$-$6$. By using radiation transfer simulations of the IGM, we consider the implications of the presence of these neutral hydrogen islands for the 21-cm power spectrum signal and its potential detection by experiments such as HERA, SKA, LOFAR, and MWA. In contrast with previous models of the 21-cm signal, we find that thanks to the late end of reionization the 21-cm power in our simulation continues to be as high as $\Delta^2_{21}=10~\mathrm{mK}^2$ at $k\sim 0.1~h/$cMpc at $z=5$-$6$. This value of the power spectrum is several orders of magnitude higher than that in the conventional models considered in the literature for these redshifts. Such high values of the 21-cm power spectrum should be detectable by HERA and SKA1-LOW in $\sim 1000$ hours, assuming optimistic foreground subtraction. This redshift range is also attractive due to relatively low sky temperature and potentially greater abundance of multiwavelength data.

In early type galaxies, externally accreted gas is thought to be the main source of gas replenishment at late times. We use MUSE integral field spectroscopy data to study the active S0 galaxy NGC 5077, known to have disturbed dynamics, indicative of a past external interaction. We confirm the presence of a stellar kinematically distinct core with a diameter of 2.8 kpc, counter-rotating with respect to the main stellar body of the galaxy. We find that the counter-rotating core consists of an old stellar population, not significantly different from the rest of the galaxy. The ionised gas is strongly warped and extends out to 6.5 kpc in the polar direction and in a filamentary structure. The gas dynamics is complex, with significant changes in the position angle as a function of radius. The ionised gas line ratios are consistent with LINER excitation by the AGN both in the nucleus and at kiloparsec scales. We discover a nuclear outflow with projected velocity V ~ 400 km/s, consistent with a hollow outflow cone intersecting the plan of the sky. The properties of the misaligned gas match predictions from numerical simulations of misaligned gas infall after a gas-rich merger. The warp and change in the gas orientation as a function of radius are consistent with gas relaxation due to stellar torques, that are stronger at small radii where the gas aligns faster than in the outer regions, driving gas to the nucleus. The stellar and gas dynamics indicate that NGC 5077 has had at least two external interactions, one that resulted in the formation of the counter-rotating core followed by late time external gas accretion. NGC 5077 illustrates the importance of external interactions in the replenishment of the galaxy gas reservoir and the nuclear gas content available for black hole fuelling.

In recent years, the availability of large, complete cluster samples has enabled numerous cosmological parameter inference analyses using cluster number counts. These have provided constraints on the cosmic matter density $\Omega_m$ and the amplitude of matter density fluctuations $\sigma_8$ alternative to those obtained from other standard probes. However, systematics uncertainties, such as the mass calibration bias and selection effects, may still significantly affect these data analyses. Hence, it is timely to explore other proxies of galaxy cluster cosmology that can provide cosmological constraints complementary to those obtained from cluster number counts. Here, we use measurements of the cluster sparsity from weak lensing mass estimates of the LC$^2$-{\it single} and HSC-XXL cluster catalogs to infer constraints on a flat $\Lambda$CDM model. The cluster sparsity has the advantage of being insensitive to selection and mass calibration bias. On the other hand, it primarily constrains a degenerate combination of $\Omega_m$ and $\sigma_8$ (along approximately constant curves of $S_8=\sigma_8\sqrt{\Omega_m/0.3}$), and to less extent the reduced Hubble parameter $h$. Hence, in order to break the internal parameter degeneracies we perform a combined likelihood analysis of cluster sparsities with cluster gas mass fraction measurements and BAO data. We find marginal constraints that are competitive with those from other standard cosmic probes: $\Omega_m=0.316\pm 0.013$, $\sigma_8=0.757\pm 0.067$ (corresponding to $S_8=0.776\pm 0.064$) and $h=0.696\pm 0.017$ at $1\sigma$. Moreover, assuming a conservative Gaussian prior on the mass bias of gas mass fraction data, we find a lower limit on the gas depletion factor $Y_{b,500c}\gtrsim 0.89$.

1I/'Oumuamua (or 1I) and 2I/Borisov (or 2I), the first InterStellar Objects (ISOs) discovered passing through the solar system, have opened up entirely new areas of exobody research. Finding additional ISOs and planning missions to intercept or rendezvous with these bodies will greatly benefit from knowledge of their likely orbits and arrival rates. Here, we use the local velocity distribution of stars from the Gaia Early Data Release 3 Catalogue of Nearby Stars and a standard gravitational focusing model to predict the velocity dependent flux of ISOs entering the solar system. With an 1I-type ISO number density of $\sim$0.1 AU$^{-3}$, we predict that a total of $\sim$6.9 such objects per year should pass within 1 AU of the Sun. There will be a fairly large high-velocity tail to this flux, with half of the incoming ISOs predicted to have a velocity at infinity, v$_{\infty}$, $>$ 40 km s$^{-1}$. Our model predicts that $\sim$92\% of incoming ISOs will be residents of the galactic thin disk, $\sim$6\% ($\sim$4 per decade) will be from the thick disk, $\sim$1 per decade will be from the halo and at most $\sim$3 per century will be unbound objects, ejected from our galaxy or entering the Milky Way from another galaxy. The rate of ISOs with very low v$_{\infty}$ $\lesssim$ 1.5 km s$^{-1}$ is so low in our model that any incoming very low velocity ISOs are likely to be previously lost solar system objects. Finally, we estimate a cometary ISO number density of $\sim$7 $\times$ 10$^{-5}$ AU$^{-3}$ for 2I type ISOs, leading to discovery rates for these objects possibly approaching once per decade with future telescopic surveys.

Upcoming full-sky large-scale structure surveys such as Euclid can probe the primordial Universe. Using the specifications for the Euclid survey, we estimate the constraints on the inflation potential beyond slow-roll. We use mock Euclid and Planck data from fiducial cosmological models using the Wiggly Whipped Inflation (WWI) framework, which generates features in the primordial power spectrum. We include Euclid cosmic shear and galaxy clustering, with two setups (Conservative and Realistic) for the non-linear cut-off. We find that the addition of Euclid data gives an improvement in constraints in the WWI potential, with the Realistic setup providing marginal improvement over the Conservative for most models. This shows that Euclid may allow us to identify oscillations in the primordial spectrum present at intermediate to small scales.

Radio sources at the highest redshifts can provide unique information on the first massive galaxies and black holes, the densest primordial environments, and the epoch of reionization. The number of astronomical objects identified at z>6 has increased dramatically over the last few years, but previously only three radio-loud (R2500>10) sources had been reported at z>6, with the most distant being a quasar at z=6.18. Here we present the discovery and characterization of P172+18, a radio-loud quasar at z=6.823. This source has an MgII-based black hole mass of ~3x10^8 Msun and is one of the fastest accreting quasars, consistent with super-Eddington accretion. The ionized region around the quasar is among the largest measured at these redshifts, implying an active phase longer than the average lifetime of the z>6 quasar population. From archival data, there is evidence that its 1.4 GHz emission has decreased by a factor of two over the last two decades. The quasar's radio spectrum between 1.4 and 3.0 GHz is steep (alpha=-1.31) and has a radio-loudness parameter R2500~90. A second steep radio source (alpha=-0.83) of comparable brightness to the quasar is only 23.1" away (~120 kpc at z=6.82; projection probability <2%), but shows no optical or near-infrared counterpart. Further follow-up is required to establish whether these two sources are physically associated.

We deploy and demonstrate the capabilities of the magnetic field model developed by Ewertowski & Basu (2013) by fitting observed polarimetry data of the prestellar core FeSt 1-457. The analytic hourglass magnetic field function derived directly from Maxwell's equations yields a central-to-surface magnetic field strength ratio in the equatorial plane, as well as magnetic field directions with relative magnitudes throughout the core. This fit emerges from a comparison of a single plane of the model with the polarization map that results from the integrated properties of the magnetic field and dust throughout the core. Importantly, our fit is independent of any assumed density profile of the core. We check the robustness of the fit by using the POLARIS code to create synthetic polarization maps that result from the integrated scattering and emission properties of the dust grains and their radiative transfer, employing an observationally-motivated density profile. We find that the synthetic polarization maps obtained from the model also provides a good fit to the observed polarimetry. Our model fits the striking feature of significant curvature of magnetic field lines in the outer part of FeSt 1-457. Combined with independent column density estimates, we infer that the core of size $R_{\rm gas}$ has a mildly supercritical mass-to-flux ratio and may have formed through dynamical motions starting from a significantly larger radius $R$. A breakdown of flux-freezing through neutral-ion slip (ambipolar diffusion) could be responsible for effecting such a transition from a large-scale magnetic field structure to a more compact gas structure.

Knowledge of the night sky radiance over a large territory may be valuable informationto identify sites appropriate to astronomical observations or for assessing the impacts ofartificial light at night on ecosystems. Measuring the sky radiance can be a complex endeavourdepending on the desired temporal and spatial resolution. Similarly, modelling of artificialnight sky radiance for multiple points of a territory can represent a significant amount ofcomputing time depending on the complexity of the model used. The use of the convolutionof a point spread function with the light sources geographical distribution has been suggestedin order to model the sky radiance over large territories of hundreds of kilometres in size.We determine how the point spread function is sensitive to the main driving parameters ofthe artificial night sky radiance such as the wavelength, the ground reflectance, the obstaclesproperties, the Upward Light Output Ratio and the Aerosol Optical Depth using the Illuminav2 model. The obtained functions were used to model the artificial night sky brightness ofthe Mont-M\'egantic International Dark Sky Reserve for winter and summer conditions. Theresults were compared to the New world atlas of artificial night sky brightness, the Illuminav2 model and in situ Sky Quality Camera measurements. We found that the New world atlasoverestimates the artificial sky brightness by 55% whereas the Illumina model underestimatesit by 48%. This may be due to varying atmospherical conditions and the fact that the modelonly accounts for public light sources.

We present observations of 86 meteor radio afterglows (MRAs) using the new broadband imager at the Long Wavelength Array Sevilleta (LWA-SV) station. The MRAs were detected using the all-sky images with a bandwidth up to 20 MHz. We fit the spectra with both a power law and a log-normal function. When fit with a power law, the spectra varied from flat to steep and the derived spectral index distribution from the fit peaked at -1.65. When fit with a log-normal function, the spectra exhibits turnovers at frequencies between 30-40 MHz, and appear to be a better functional fit to the spectra. We compared the spectral parameters from the two fitting methods with the physical properties of MRAs. We observe a weak correlation between the log-normal turnover frequency and the altitude of MRAs. However, the spectral indices from the power law fit do not show any strong correlations with the physical properties of MRAs.

Atom-in-jellium calculations of the electron states, and perturbative calculations of the Einstein frequency, were used to construct equations of state (EOS) from around $10^{-5}$ to $10^7$g/cm$^3$ and $10^{-4}$ to $10^{6}$eV for elements relevant to white dwarf (WD) stars. This is the widest range reported for self-consistent electronic shell structure calculations. Elements of the same ratio of atomic weight to atomic number were predicted to asymptote to the same $T=0$ isotherm, suggesting that, contrary to recent studies of the crystallization of WDs, the amount of gravitational energy that could be released by separation of oxygen and carbon is small. A generalized Lindemann criterion based on the amplitude of the ion-thermal oscillations calculated using atom-in-jellium theory, previously used to extrapolate melt curves for metals, was found to reproduce previous thermodynamic studies of the melt curve of the one component plasma with a choice of vibration amplitude consistent with low pressure results. For elements for which low pressure melting satisfies the same amplitude criterion, such as Al, this melt model thus gives a likely estimate of the melt curve over the full range of normal electronic matter; for the other elements, it provides a useful constraint on the melt locus.

Black hole - neutron star (BH-NS) mergers are a major target for ground-based gravitational wave (GW) observatories. A merger can also produce an electromagnetic counterpart (a kilonova) if it ejects neutron-rich matter that assembles into heavy elements through r-process nucleosynthesis. We study the kilonova signatures of the unbound dynamical ejecta of a BH-NS merger. We take as our initial state the results from a numerical relativity simulation, and then use a general relativistic hydrodynamics code to study the evolution of the ejecta with parameterized r-process heating models. The unbound dynamical ejecta is initially a flattened, directed tidal tail largely confined to a plane. Heating from the r-process inflates the ejecta into a more spherical shape and smooths its small-scale structure, though the ejecta retains its bulk directed motion. We calculate the electromagnetic signatures using a 3D radiative transfer code and a parameterized opacity model for lanthanide-rich matter. The light curve varies with viewing angle due to two effects: asphericity results in brighter emission for orientations with larger projected areas, while Doppler boosting results in brighter emission for viewing angles more aligned with the direction of bulk motion. For typical r-process heating rates, the peak bolometric luminosity varies by a factor of $\sim 3$ with orientation while the peak in the optical bands varies by $\sim 3$ magnitudes. The spectrum is blue-shifted at viewing angles along the bulk motion, which increases the $V$-band peak magnitude to $\sim -14$ despite the lanthanide-rich composition.

We present a new study of the merger dynamics of Abell~1775 by analyzing the high-quality Chandra and XMM-Newton archival data. We confirm/identify an arc-shaped edge (i.e., the head) at $\sim48$~kpc west of the X-ray peak, a split cold gas tail that extends eastward to $\sim163$~kpc, and a plume of spiral-like X-ray excess (within about $81-324$~kpc northeast of the cluster core) that connects to the end of the tail. The head, across which the projected gas temperature rises outward from $3.39_{-0.18}^{+0.28}$~keV to $5.30_{-0.43}^{+0.54}$~keV, is found to be a cold front with a Mach number of $\mathcal{M}\sim0.79$. Along the surfaces of the cold front and tail, typical KHI features (noses and wings, etc.) are found and are used to constrain the upper limit of the magnetic field ($\sim11.2~\mu$G) and the viscosity suppression factor ($\sim0.01$). Combining optical and radio evidence we propose a two-body merger (instead of systematic motion in a large-scale gas environment) scenario and have carried out idealized hydrodynamic simulations to verify it. We find that the observed X-ray emission and temperature distributions can be best reproduced with a merger mass ratio of 5 after the first pericentric passage. The NAT radio galaxy is thus more likely to be a single galaxy falling into the cluster center at a relative velocity of 2800~$\rm km~s^{-1}$, a speed constrained by its radio morphology. The infalling subcluster is expected to have a relatively low gas content, because only a gas-poor subcluster can cause central-only disturbances as observed in such an off-axis merger.

In this paper, we report the first extended GeV $\gamma$-ray emission, at a significant level of $\sim$ 8.13$\sigma$, is reported from the region of the supernova remnant (SNR) SNR G317.3-0.2 by analyzing $\sim$ 12.2 years of Fermi Large Area Telescope (Fermi-LAT) Pass 8 data in the work. The best-fit position of the new $\gamma$-ray source matches that of the 843 MHz radio energy band of SNR G317.3-0.2, and there is no significant variability of the photon flux of the corresponding light curve (LC) in the data for the 12.2 year period; therefore, by excluding other known $\gamma$-ray sources or candidates within a 2$\sigma$ error radius from the best-fit position of SNR G317.3-0.2, we suggest that the $\gamma$-ray source is likely to be a GeV counterpart of SNR G317.3-0.2.

Using comoving distance $d_c$ and angular diameter distance $d_A$, we recalculate parameters describing kinematical state of the universe, still combining the kinematical model of universe but not relying on dynamical equations for gravity. Comoving distance $d_c$ comes from Hubble data H(z) and is more reliable. Angular diameter distance $d_A$ comes from SZE (Sunyaev-Zel dovich Effect) and X-ray data, and needs calibration. In low redshift case, we use expansion of relation between luminosity distance and redshift about redshift $z$; in high redshift case, we take variable substitution $y=1/(1+z)$, and expand the relation between luminosity distance and redshift about variable $y$ in order to reduce computational errors. Finally we get the more precise value of Hubble parameter $H_0=69.13\pm 0.24{\kern 1pt} km{\kern 1pt} \cdot {s^{ - 1}} \cdot Mp{c^{ - 1}}$, corresponding to 0.4\% uncertainty in $68.3\%$ confidence region, also deceleration factor $q_0=-0.57\pm0.04 $ and acceleration rate $j_0=1.28\pm0.33$, and their statistical values and probability graph. We compare the values of ${H_0}$, ${q_0}$, ${j_0}$ with those obtained from other observation data and model.

Radio Active Galactic Nuclei (RAGN) are found preferentially in dense structures (i.e., clusters/groups) at redshifts of z$<$2 and are commonly used to detect protoclusters at higher redshift. Here, we attempt to study the host and environmental properties of two relatively faint ($\mathrm L_\mathrm{1.4GHz} \sim10^{25}$ W Hz$^{-1}$) RAGN in a known protocluster at z=3.3 in the PCl J0227-0421 field, detected using the latest radio observation obtained as part of the ORELSE Survey. Using new spectroscopic observations obtained from Keck/MOSFIRE as part of the Charting Cluster Construction with VUDS and ORELSE (C3VO) survey and previous spectroscopic data obtained as part of the VIMOS-VLT Deep Survey (VVDS) and VIMOS Ultra-Deep Survey (VUDS), we revise the three-dimensional overdensity field around this protocluster. The protocluster is embedded in a large scale overdensity proto-structure. This proto-structure has an estimated total mass of $\sim2.6\times10^{15}$ M$_\odot$ and contains several overdensity peaks. Both RAGN are hosted by very bright and massive galaxies, while their hosts show extreme differences color, indicating that they have different ages and are in different evolutionary stages. Furthermore, we find that they are not in the most locally dense parts of the proto-structure, but are fairly close to the centers of their parent overdensity peaks. We propose a scenario where merging might already have happened in both cases that have lowered the local density of their surrounding area and boosted their stellar mass. This work is the first time that two RAGN at low-luminosity have been found and studied within a high redshift proto-structure.

We present the results of a study of the prospect of detecting habitable Trojan planets in the Kepler Habitable Zone circumbinary planetary systems (Kepler-16, -47, -453, -1647, -1661). We integrated the orbits of 10,000 separate N-body systems (N=4,6), each with a one Earth-mass body in a randomly selected orbit near the L4 and L5 Lagrangian points of the host HZ circumbinary planet. We find that stable Trojan planets are restricted to a narrow range of semimajor axes in all five systems and limited to small eccentricities in Kepler-16, -47, and -1661. To assess the prospect of the detection of these habitable Trojan planets, we calculated the amplitudes of the variations they cause in the transit timing of their host bodies. Results show that the mean amplitudes of the transit timing variations (TTVs) correlate with the mass of the transiting planet and range from 70 minutes for Kepler-16b to 390 minutes for Kepler-47c. Our analysis indicates that the TTVs of the circumbinary planets caused by these Trojan bodies fall within the detectable range of timing precision obtained from the Kepler telescope's long-cadence data. The latter points to Kepler data as a viable source to search for habitable Trojan planets.

We present high angular resolution imaging of the quasar PSO J172.3556+18.7734 at $z=6.82$ with the Very Long Baseline Array (VLBA). This source currently holds the record of being the highest redshift radio-loud quasar. These observations reveal a dominant radio source with a flux density of $398.4 \pm 61.4~\mu$Jy at 1.53 GHz, a deconvolved size of $9.9 \times 3.5$ mas ($52.5 \times 18.6$ pc), and an intrinsic brightness temperature of ($4.7 \pm 0.7) \times 10^7$ K. A weak unresolved radio extension from the main source is also detected at $\sim~3.1\sigma$ level. The total flux density recovered with the VLBA at 1.53 GHz is consistent with that measured with the Very Large Array (VLA) at a similar frequency. The quasar is not detected at 4.67 GHz with the VLBA, suggesting a steep spectral index with a limit of $\alpha^{1.53}_{4.67} < -$1.55. The quasar is also not detected with the VLBA at 7.67 GHz. The overall characteristics of the quasar suggest that it is a very young radio source similar to lower redshift Gigahertz Peaked Spectrum radio sources, with an estimated kinematic age of $\sim~10^3$ years. The VLA observations of this quasar revealed a second radio source in the field $23\rlap{.}{''}1$ away. This radio source, which does not have an optical or IR counterpart, is not detected with the VLBA at any of the observed frequencies. Its non-detection at the lowest observed VLBA frequency suggests that it is resolved out, implying a size larger than ~$0\rlap{.}{''}17$. It is thus likely situated at lower redshift than the quasar.

Massive stars have a strong impact on their local environments. However, how stellar feedback regulates star formation is still under debate. In this context, we studied the chemical properties of 80 dense cores in the Orion molecular cloud complex composed of the Orion A (39 cores), B (26 cores), and lambda Orionis (15 cores) clouds using multiple molecular line data taken with the Korean Very Long Baseline Interferometry Network (KVN) 21-m telescopes. The lambda Orionis cloud has an H ii bubble surrounding the O-type star lambda Ori, and hence it is exposed to the ultraviolet (UV) radiation field of the massive star. The abundances of C2H and HCN, which are sensitive to UV radiation, appear to be higher in the cores in the lambda Orionis cloud than those in the Orion A and B clouds, while the HDCO to H2CO abundance ratios show an opposite trend, indicating a warmer condition in the lambda Orionis cloud. The detection rates of dense gas tracers such as the N2H+, HCO+, and H13CO+ lines are also lower in the lambda Orionis cloud. These chemical properties imply that the cores in the lambda Orionis cloud are heated by UV photons from lambda Ori. Furthermore, the cores in the lambda Orionis cloud do not show any statistically significant excess in the infall signature of HCO+ (1 - 0), unlike the Orion A and B clouds. Our results support the idea that feedback from massive stars impacts star formation in a negative way by heating and evaporating dense materials, as in the lambda Orionis cloud.

NGC 2617 has attracted a lot of attention after the detection of the changes in spectral type, and its geometry and kinematics of broad-line region (BLR) are still ambiguous. In this paper, we present the high cadence ($\sim$ 2 days) reverberation mapping campaign of NGC 2617 from 2019 October to 2020 May undertaken at Lijiang 2.4 m telescope. For the first time, the velocity-resolved reverberation signature of the object was successfully detected. Both H$\alpha$ and H$\beta$ show an asymmetrical profile with a peak in the velocity-resolved time lags. For each of both lines, the lag of the line core is longer than those of the relevant wings, and the peak of the velocity-resolved lags is slightly blueshifted. These characteristics are not consistent with the theoretical prediction of the inflow, outflow or Keplerian disk model. Our observations give the time lags ofH$\alpha$, H$\beta$, H$\gamma$, and He I, with a ratio of $\tau_{\rm{H}\alpha}$:$\tau_{\rm{H}\beta}$:$\tau_{\rm{H}\gamma}$:$\tau_{\rm{He~I}}$ = 1.27:1.00:0.89:0.20, which indicates a stratified structure in the BLR of the object. It is the first time that the lags of H$\alpha$ and He I are obtained. Assuming a virial factor of $f$ = 5.5 for dispersion width of line, the masses of black hole derived from H$\alpha$ and H$\beta$ are $\rm{23.8^{+5.4}_{-2.7}}$ and $\rm{21.1^{+3.8}_{-4.4}} \times 10^{6}M_{\odot}$, respectively. Our observed results indicate the complexity of the BLR of NGC 2617.

Globular clusters (GCs) are important tools to understand the formation and evolution of the Milky Way (MW). The known MW sample is still incomplete, so the discovery of new GC candidates and the confirmation of their nature are crucial for the census of the MW GC system. Our goal is to confirm the physical nature of two GC candidates: Patchick99 and TBJ3, located towards the Galactic bulge. We use public data in the near-IR from the VVV, VVVX and 2MASS along the with deep optical data from the Gaia DR2, in order to estimate their main physical parameters: reddening, extinction, distance, luminosity, mean cluster proper motions (PMs), size, metallicity and age. We investigate both candidates at different wavelengths. We use near-IR and optical CMDs in order to analyse Patchick99. We decontaminate CMDs following a statistical procedure and PM-selection. Reddening and extinction are derived by adopting reddening maps. Metallicity and age are evaluated by fitting stellar isochrones. Reddening and extinction are E(J-Ks)=0.12+/-0.02 mag, AKs=0.09+/-0.01 mag from the VVV data, whereas E(BP-RP)=0.21+/-0.03 mag, AG=0.68+/-0.08 mag from Gaia DR2. We estimate a distance d=6.4+/-0.2 kpc in near-IR and D=7.0+/-0.2 kpc in optical. We derive its metallicity and age fitting PARSEC isochrones, finding [Fe/H]=-0.2+/-0.2 dex and t=10+/-2 Gyr. The mean PMs for Patchick99 are pmRA=-298+/-1.74 mas/yr and pmDEC=-5.49+/-2.02 mas/yr. We confirm that it is a low-luminosity GC, with MKs=-7.0+/-0.6 mag. The radius estimation is performed building the radial density profile, finding r~10'. We recognise 7 RR Lyrae star members within 8.2 arcmin from its centre, confirming the distance found by other methods. We found that TBJ3 shows mid-IR emissions that are not present in GCs. We discard TBJ3 as GC candidate and we focus on Patchick99. We conclude that it is an old metal-rich GC, situated in the Galactic bulge.

In protoplanetary disks, zones of dense particle configuration promote planet formation. Solid particles in dense clouds alter their motion through collective effects and back reaction to the gas. The effect of particle-gas feedback with ambient solid-to-gas ratios $\epsilon > 1$ on the stopping time of particles is investigated. In experiments on board the International Space Station we studied the evolution of a dense granular gas while interacting with air. We observed diffusion of clusters released at the onset of an experiment but also the formation of new dynamical clusters. The solid-to-gas mass ratio outside the cluster varied in the range of about $\epsilon_{\rm avg} \sim 2.5 - 60$. We find that the concept of gas drag in a viscous medium still holds, even if the medium is strongly dominated in mass by solids. However, a collective factor has to be used, depending on $\epsilon_{\rm avg} $, i.e. the drag force is reduced by a factor 18 at the highest mass ratios. Therefore, flocks of grains in protoplanetary disks move faster and collide faster than their constituents might suggest.

In this Letter we construct the Hubble diagram for a Universe where dark matter is universally charged under a dark non-linear electromagnetic force which features a screening mechanism of the K-mouflage type for repulsive forces. By resorting to the Newtonian approximation, we explicitly show that the cosmological evolution generates an inhomogeneous Hubble diagram that corresponds to a curvature dominated expansion at short distances and converges to the cosmological one of $\Lambda$CDM. We discuss the potential impact of this inhomogeneous profile on the Hubble tension. For completeness, we explicitly show how the Newtonian approximation can be derived from an inhomogeneous relativistic Lema\^itre model.

A number of solar filaments/prominences demonstrate failed eruptions, when a filament at first suddenly starts to ascend and then decelerates and stops at some greater height in the corona. The mechanism of the termination of eruptions is not clear yet. One of the confining forces able to stop the eruption is the gravity force. Using a simple model of a partial current-carrying torus loop anchored to the photosphere and photospheric magnetic field measurements as the boundary condition for the potential magnetic field extrapolation into the corona, we estimated masses of 15 eruptive filaments. The values of the filament mass show rather wide distribution in the range of $4\times10^{15}$ -- $270\times10^{16}$g. Masses of the most of filaments, laying in the middle of the range, are in accordance with estimations made earlier on the basis of spectroscopic and white-light observations.

Context. Magnetic helicity is a physical quantity of great importance in the study of astrophysical and natural plasmas. Although a density for helicity cannot be defined, a good proxy for it is field line helicity. The appropriate quantity for use in solar conditions is relative field line helicity (RFLH). Aims. This work aims to study in detail the behaviour of RFLH, for the first time, in a solar active region (AR). Methods. The target active region is the large, eruptive AR 11158. In order to compute RFLH and all other quantities of interest we use a non-linear force-free reconstruction of the AR coronal magnetic field of excelent quality. Results. We find that the photospheric morphology of RFLH is quite different than that of the magnetic field or of the electrical current, and this is not sensitive to the chosen gauge in the computation of RFLH. The value of helicity experiences a large decrease, 25% of its pre-flare value, during an X-class flare of the AR, a change that is also depicted in the photospheric morphology of RFLH. Moreover, the area of this change coincides with the area that encompasses the flux rope, the magnetic structure that later erupted. Conclusions. The use of RFLH can provide important information about the value and location of the magnetic helicity expelled from the solar atmosphere during eruptive events.

AN Cam is a little-studied eclipsing binary containing somewhat evolved components in an orbit with a period of 21.0 d and an eccentricity of 0.47. A spectroscopic orbit based on photoelectric radial velocities was published in 1977. AN Cam has been observed using the TESS satellite in three sectors: the data were obtained in long-cadence mode and cover nine eclipses. By modelling these data and published radial velocities we obtain masses of 1.380 +/- 0.021 Msun and 1.402 +/- 0.025 Msun, and radii of 2.159 +/- 0.012 Rsun and 2.646 +/- 0.014 Rsun. We also derive a precise orbital ephemeris from these data and recent times of minimum light, but find that the older times of minimum light cannot be fitted assuming a constant orbital period. This could be caused by astrophysical or instrumental effects; forthcoming TESS observations will help the investigation of this issue. We use the Gaia EDR3 parallax and optical/infrared apparent magnitudes to measure effective temperatures of 6050 +/- 150 K and 5750 +/- 150 K: the primary star is hotter but smaller and less massive than its companion. A comparison with theoretical models indicates that the system has an approximately solar chemical composition and an age of 3.3 Gyr. Despite the similarity of their masses the two stars are in different evolutionary states: the primary is near the end of its main-sequence lifetime and the secondary is now a subgiant. AN Cam is a promising candidate for constraining the strength of convective core overshooting in 1.4 Msun stars.

In this paper, we aim to study the main properties and luminosity function (LF) of the [OII] emitters detected in the OTELO survey in order to characterise the star formation processes in low-mass galaxies at $z\sim1.43$ and to constrain the faint-end of the LF. Here, we describe the selection method and analysis of the emitters obtained from narrow-band scanning techniques. In addition, we present several relevant properties of the emitters and discuss the selection biases and uncertainties in the determination of the LF and the star formation rate density (SFRD). We confirmed a total of 60 sources from a preliminary list of 332 candidates as [OII] emitters. Approximately 93% of the emitters have masses in the range of $10^{8}<M_{*}/{\rm M_{\odot}}<10^{9}$. All of our emitters are classified as late-type galaxies, with a lower value of $(u-v)$\, when compared with the rest of the emitters of the OTELO survey. We find that the cosmic variance strongly affects the normalisation ($\phi^*$) of the LF and explains the discrepancy of our results when compared with those obtained from surveys of much larger volumes. However, we are able to determine the faint-end slope of the LF, namely, $\alpha=-1.42\pm0.06$, by sampling the LF down to $\sim1$\,dex lower than in previous works. We present our calculation of the SFRD of our sample and compare it to the value obtained in previous studies from the literature.

We report the discovery of a new high mass X-ray binary pulsar, XMMU J050722.1-684758, possibly associated with the supernova remnant MCSNR J0507-6847 in the Large Magellanic Cloud, using XMM-Newton X-ray observations. Pulsations with a periodicity of 570 s are discovered from the Be X-ray binary XMMU J050722.1-684758 confirming its nature as a HMXB pulsar. The HMXB is located near the geometric centre of the supernova remnant MCSNR J0507-6847 (0.9 arcmin from the centre) which supports the XRB-SNR association. The estimated age of the supernova remnant is 43-63 kyr which points to a middle aged to old supernova remnant. The large diameter of the supernova remnant combined with the lack of distinctive shell counterparts in optical and radio indicates that the SNR is expanding into the tenous environment of the superbubble N103. The estimated magnetic field strength of the neutron star is $B\gtrsim10^{14}$ G assuming a spin equilibrium condition which is expected from the estimated age of the parent remnant and assuming that the measured mass-accretion rate remained constant throughout.

In the paper, we consider two models in which dark energy is coupled with either dust matter or dark matter, and discuss the conditions that allow more time for structure formation to take place at high redshifts. These models are expected to have a larger age of the universe than that of $\Lambda$CDM [universe consists of cold dark matter (CDM) and dark energy (a cosmological constant, $\Lambda$)], so it can explain the formation of high redshift gravitationally bound systems which the $\Lambda$CDM model cannot interpret. We use the observational Hubble parameter data (OHD) and Hubble parameter obtained from cosmic chronometers method ($H(z)$) in combination with baryon acoustic oscillation (BAO) data to constrain these models. With the best-fitting parameters, we discuss how the age, the deceleration parameter, and the energy density parameters evolve in the new universes, and compare them with that of $\Lambda$CDM.

Spectroscopic studies of Galactic O and B stars show that many stars with masses above 8 M$_{\odot}$ are observed in the HR diagram just beyond the Main-Sequence (MS) band predicted by stellar models computed with a moderate overshooting. This may be an indication that the convective core sizes in stars in the upper part of the HR diagram are larger than predicted by these models. Combining stellar evolution models and spectroscopic parameters derived for a large sample of Galactic O and B stars, including brand new information about their projected rotational velocities, we reexamine the question of the convective core size in MS massive stars. We confirm that for stars more massive than about 8 M$_{\odot}$, the convective core size at the end of the MS phase increases more rapidly with the mass than in models computed with a constant step overshoot chosen to reproduce the main sequence width in the low mass range (around 2 M$_{\odot}$). This conclusion is valid for both the cases of non-rotating models and rotating models either with a moderate or a strong angular momentum transport. The increase of the convective core mass with the mass obtained from the TAMS position is, however, larger than the one deduced from the surface velocity drop for masses above about 15 M$_{\odot}$. Although observations available at the moment cannot decide what is the best choice between the core sizes given by the TAMS and the velocity drop, we discuss different methods to get out of this dilemma. At the moment, comparisons with eclipsing binaries seem to favor the solution given by the velocity drop. While we confirm the need for larger convective cores at higher masses, we find tensions in-between different methods for stars more massive than 15 M$_{\odot}$. The use of single-aged stellar populations (non-interacting binaries or stellar clusters) would be a great asset to resolve this tension.

We report the results of optical spectroscopy of the Small Magellanic Cloud supernova remnant (SNR) MCSNR J0127-7332 and the mass donor Be star, 2dFS 3831, in its associated high-mass X-ray binary SXP 1062 carried out with the Southern African Large Telescope (SALT). Using high-resolution long-slit spectra, we measured the expansion velocity of the SNR shell of \approx 140 km/s, indicating that MCSNR J0127-7332 is in the radiative phase. We found that the observed line ratios in the SNR spectrum can be understood if the local interstellar medium is ionized by 2dFS 3831 and/or OB stars around the SNR. We propose that MCSNR J0127-7332 is the result of supernova explosion within a bubble produced by the stellar wind of the supernova progenitor and that the bubble was surrounded by a massive shell at the moment of supernova explosion. We estimated the age of MCSNR J0127-7332 to be \la 10 000 yr. We found that the spectrum of 2dFS 3831 changes with orbital phase. Namely, the equivalent width of the Halpha emission line decreased by \approx 40 per cent in \approx 130 d after periastron passage of the neutron star and then almost returned to its original value in the next \approx 100 d. Also, the spectrum of 2dFS 3831 obtained closest to the periastron epoch (about three weeks after the periastron) shows a noticeable emission line of He II \lambda 4686, which disappeared in the next about two weeks. We interpret these changes as a result of the temporary perturbation and heating of the disk as the neutron star passes through it.

The recent rediscovery of magnetic field switchbacks or deflections embedded in the solar wind flow by the Parker Solar Probe mission lead to a huge interest in the modelling of the formation mechanisms and origin of these switchbacks. Several scenarios for their generation were put forth, ranging from lower solar atmospheric origins by reconnection, to being a manifestation of turbulence in the solar wind, and so on. Here we study some potential formation mechanisms of magnetic switchbacks in the lower solar atmosphere, using three-dimensional magneto-hydrodynamic (MHD) numerical simulations. The model is that of an intense flux tube in an open magnetic field region, aiming to represent a magnetic bright point opening up to an open coronal magnetic field structure, e.g. a coronal hole. The model is driven with different plasma flows in the photosphere, such as a fast up-shooting jet, as well as shearing flows generated by vortex motions or torsional oscillations. In all scenarios considered, we witness the formation of magnetic switchbacks in regions corresponding to chromospheric heights. Therefore, photospheric plasma flows around the foot-points of intense flux tubes appear to be suitable drivers for the formation of magnetic switchbacks in the lower solar atmosphere. Nevertheless, these switchbacks do not appear to be able to enter the coronal heights of the simulation in the present model. In conclusion, based on the presented simulations, switchbacks measured in the solar wind are unlikely to originate from photospheric or chromospheric dynamics.

Jupiter's moon Io is the most volcanically active body in the Solar System with hundreds of active volcanoes varying in intensity on different timescales. Io has been observed during occultations by other Galilean moons and Jupiter since the 1980s, using high-cadence near infrared photometry. These observations encode a wealth of information about the volcanic features on its surface. We built a generative model for the observed occultations using the code starry which enables fast, analytic, and differentiable computation of occultation light curves in emitted and reflected light. Our probabilistic Bayesian model is able to recover known hotspots on the surface of Io using only two light curves and without any assumptions on the locations, shapes or the number of spots. The methods we have developed are also directly applicable to the problem of mapping the surfaces of stars and exoplanets.

The detection of gravity modes is expected to give us unprecedented insights into the inner dynamics of the Sun. Within this framework, predicting their amplitudes is essential to guide future observational strategies and seismic studies. In this work, we predict the amplitude of low-frequency asymptotic gravity modes generated by penetrative convection at the top of the radiative zone. The result is found to depend critically on the time evolution of the plumes inside the generation region. Using a solar model, we compute the GOLF apparent surface radial velocity of low-degree gravity modes in the frequency range $10~\mu H_z\le \nu \le 100~\mu H_z$. In case of a Gaussian plume time evolution, gravity modes turn out to be undetectable because of too small surface amplitudes. This holds true despite a wide range of values considered for the parameters of the model. In the other limiting case of an exponential time evolution, plumes are expected to drive gravity modes in a much more efficient way because of a much higher temporal coupling between the plumes and the modes than in the Gaussian case. Using reasonable values for the plume parameters based on semi-analytical models, the apparent surface velocities in this case turn out to be one order of magnitude smaller than the 22-years GOLF detection threshold and than the previous estimates considering turbulent pressure as the driving mechanism, with a maximum value of $0.05$ cm s${}^{-1}$ for $\ell =1$ and $\nu\approx 100~\mu H_z$. When accounting for uncertainties on the plume parameters, the apparent surface velocities in the most favorable plausible case become comparable to those predicted with turbulent pressure, and the GOLF observation time required for a detection at $ \nu \approx100~\mu H_z$ and $\ell=1$ is reduced to about 50 yrs.

The Ultraviolet Imaging Telescope (UVIT) onboard the AstroSat observatory has imaged the Andromeda Galaxy (M31) from 2017 to 2019 in FUV and NUV with the high spatial resolution of ~1". The survey covered the large sky area of M31 with a set of observations (Fields) each 28 arcminutes in diameter. Field 1 was observed in two epochs with the F148W filter, separated by 1133 days (~3.10 years). The 6.4 kpc diameter Field 1 (at the distance of M31) includes a substantial part of the inner spiral arms of the galaxy. We identify UVIT sources in both epochs of Field 1 and obtain catalogs of sources that are variable in FUV at > 3 sigma and > 5 sigma confidence level. The fraction of FUV variable sources is higher for brighter sources, and the fraction is higher in the two main spiral arms compared to other areas. This is evidence that a significant fraction of the FUV variables are associated with hot young stars. Source counterparts are found for 42 of the 86 > 5 sigma FUV variables using existing catalogs. The counterparts include 10 star clusters, 6 HII regions, 5 regular or semiregular variables, 6 other variables and 6 nova or nova candidates. The UVIT FUV-NUV and FUV-FUV color-magnitude diagrams confirm the association of most of the FUV variables with hot young stars. A catalog of UVIT photometry for the variable sources is presented.

The amount, size, and complexity of astronomical data-sets and databases are growing rapidly in the last decades, due to new technologies and dedicated survey telescopes. Besides dealing with poly-structured and complex data, sparse data has become a field of growing scientific interest. A specific field of Astroinformatics research is the estimation of redshifts of extra-galactic sources by using sparse photometric observations. Many techniques have been developed to produce those estimates with increasing precision. In recent years, models have been favored which instead of providing a point estimate only, are able to generate probabilistic density functions (PDFs) in order to characterize and quantify the uncertainties of their estimates. Crucial to the development of those models is a proper, mathematically principled way to evaluate and characterize their performances, based on scoring functions as well as on tools for assessing calibration. Still, in literature inappropriate methods are being used to express the quality of the estimates that are often not sufficient and can potentially generate misleading interpretations. In this work we summarize how to correctly evaluate errors and forecast quality when dealing with PDFs. We describe the use of the log-likelihood, the continuous ranked probability score (CRPS) and the probability integral transform (PIT) to characterize the calibration as well as the sharpness of predicted PDFs. We present what we achieved when using proper scoring rules to train deep neural networks as well as to evaluate the model estimates and how this work led from well calibrated redshift estimates to improvements in probabilistic weather forecasting. The presented work is an example of interdisciplinarity in data-science and illustrates how methods can help to bridge gaps between different fields of application.

Recent detections of gravitational waves from mergers of neutron stars (NSs) and black holes (BHs) in the low and high-end mass gap regimes (with masses between ~2-5 M_Sun and exceeding ~50 M_Sun, respectively) pose a puzzle to standard stellar and binary evolution theory. Mass-gap mergers may originate from successive mergers in hierarchical systems such as quadruples. Here, we consider repeated mergers of NSs and BHs in stellar 2+2 quadruple systems. Under certain circumstances, secular evolution acts to accelerate the merger of one of the inner binaries. Subsequently, the merger remnant may interact with the companion binary, yielding a second-generation merger event. We model the initial stellar and binary evolution of the inner binaries as isolated systems. In the case of successful compact object formation, we subsequently follow the secular dynamical evolution of the quadruple system. When a merger occurs, we take into account merger recoil, and model subsequent evolution using direct N-body methods. With different assumptions on the initial binary properties, we find that the majority of first-generation mergers are not much affected by secular evolution, with their observational properties mostly consistent with isolated binaries. A small subset shows imprints of secular evolution through residual eccentricity in the LIGO band, and retrograde spin-orbit orientations. Second-generation mergers can be strongly affected by scattering (i.e., three-body interactions) induced by the first-generation merger. In particular, scattering can account for mergers within the low-end mass gap, although not the high-end mass gap. Also, scattering could explain highly eccentric LIGO sources and negative effective spin parameters.

We perform radiative magnetohydrodynamic calculations for the solar quiet region to investigate the dependence of statistical flow on magnetic properties and the three-dimensional (3D) structure of magnetic patches in the presence of large-scale flow that mimics differential rotation. It has been confirmed that strong magnetic field patches move faster in the longitudinal direction at the solar surface. Consequently, strong magnetic patches penetrate deeper into the solar interior. The motion of the deep-rooted magnetic patches is influenced by the faster differential rotation in the deeper layer. In this study, we perform realistic radiative magnetohydrodynamic calculations using R2D2 code to validate that stronger patches have deeper roots. We also add large-scale flow to mimic the differential rotation. The magnetic patches are automatically detected and tracked, and we evaluate the depth of 30,000 magnetic patches. The velocities of 2.9 million magnetic patches are then measured at the photosphere. We obtain the dependence of these values on the magnetic properties, such as field strength and flux. Our results confirm that strong magnetic patches tend to show deeper roots and faster movement, and we compare our results with observations using the point spread function of instruments at the Hinode and Solar Dynamics Observatory (SDO). Our result is quantitatively consistent with previous observational results of the SDO.

We present the first identification in interstellar space of the propargyl radical (CH2CCH). This species was observed in the cold dark cloud TMC-1 using the Yebes 40m telescope. The six strongest hyperfine components of the 2,0,2-1,0,1 rotational transition, lying at 37.46~GHz, were detected with signal-to-noise ratios in the range 4.6-12.3 sigma. We derive a column density of 8.7e13 cm-2 for CH2CCH, which translates to a fractional abundance relative to H2 of 8.7e-9. This radical has a similar abundance to methyl acetylene, with an abundance ratio CH2CCH/CH3CCH close to one. The propargyl radical is thus one of the most abundant radicals detected in TMC-1, and it is probably the most abundant organic radical with a certain chemical complexity ever found in a cold dark cloud. We constructed a gas-phase chemical model and find calculated abundances that agree with, or fall two orders of magnitude below, the observed value depending on the poorly constrained low-temperature reactivity of CH2CCH with neutral atoms. According to the chemical model, the propargyl radical is essentially formed by the C + C2H4 reaction and by the dissociative recombination of C3Hn+ ions with n = 4-6. The propargyl radical is believed to control the synthesis of the first aromatic ring in combustion processes, and it probably plays a key role in the synthesis of large organic molecules and cyclization processes to benzene in cold dark clouds.

The reaction between atomic oxygen and molecular hydrogen is an important one in astrochemistry as it regulates the abundance of the hydroxyl radical and serves to open the chemistry of oxygen in diverse astronomical environments. However, the existence of a high activation barrier in the reaction with ground state oxygen atoms limits its efficiency in cold gas. In this study we calculate the dependence of the reaction rate coefficient on the rotational and vibrational state of H$_2$ and evaluate the impact on the abundance of OH in interstellar regions strongly irradiated by far-UV photons, where H2 can be efficiently pumped to excited vibrational states. We use a recently calculated potential energy surface and carry out time-independent quantum mechanical scattering calculations to compute rate coefficients for the reaction O(3P) + H2(v,j) -> OH + H, with H2 in vibrational states v = 0-7 and rotational states j = 0-10. We find that the reaction becomes significantly faster with increasing vibrational quantum number of H2, although even for high vibrational states of H2 (v = 4-5) for which the reaction is barrierless, the rate coefficient does not strictly attain the collision limit and still maintains a positive dependence with temperature. We implemented the calculated state-specific rate coefficients in the Meudon PDR code to model the Orion Bar PDR and evaluate the impact on the abundance of the OH radical. We find the fractional abundance of OH is enhanced by up to one order of magnitude in regions of the cloud corresponding to Av = 1.3-2.3, compared to the use of a thermal rate coefficient for O + H2, although the impact on the column density of OH is modest, of about 60 %. The calculated rate coefficients will be useful to model and interpret JWST observations of OH in strongly UV-illuminated environments.

We investigate a generalized form of the Phenomenologically Emergent Dark Energy (PEDE) model, known as Generalized Emergent Dark Energy (GEDE), introduced in~\cite{Li:2020ybr} in light of a series of cosmological probes and considering the evolution of the model at the level of linear perturbations. This model introduces a free parameter $\Delta$ that can discriminate between the $\Lambda$CDM (corresponds to $\Delta=0$) or the PEDE (corresponds to $\Delta=1$) models, allowing us to determine which model is preferred most by the fit of the observational datasets. We find a strong evidence of the GEDE scenario for most of the employed observational datasets. In particular, we find that $\Lambda$CDM model is disfavored at more than $2\sigma$ CL for most of the observational datasets considered in this work and PEDE is in agreement with Planck 2018+BAO+R19 combination within $1\sigma$. Finally, a Bayesian Model comparison shows a strong evidence for GEDE against $\Lambda$CDM for most of the dataset combinations.

Measurements of visible and near-infrared reflection (0.38-5 {\mu}m) and mid to far infrared emission (5-200 {\mu}m) from telescope and satellite remote sensing instruments make it possible to investigate the composition of planetary surfaces via electronic transitions and vibrational modes of chemical bonds. Red spectral slopes at visible and near infrared wavelengths and absorption features at 3.3 and 3.4 {\mu}m observed in circumstellar disks, the interstellar medium, and on the surfaces of solar-system bodies are interpreted to be due to the presence of organic material and other carbon compounds. Identifying the origin of these features requires measurements of the optical properties of a variety of relevant analog and planetary materials. Spectroscopic models of dust within circumstellar disks and the interstellar medium as well as planetary regoliths often incorporate just one such laboratory measurement despite the wide variation in absorption and extinction properties of organic and other carbon-bearing materials. Here we present laboratory measurements of transmission spectra in the 1.5-13 {\mu}m region and use these to derive real and imaginary indices of refraction for two samples: 1) an analog to meteoritic insoluble organic matter and 2) a powdered Allende meteorite sample. We also test our refractive index retrieval method on a previously published transmission spectrum of an Mg-rich olivine. We compare optical measurements of the insoluble organic-matter analog to those of other solar-system and extrasolar organic analogs, such as amorphous carbon and tholins, and find that the indices of refraction of the newly characterized material differ significantly from other carbonaceous samples.

Prompted by a recent paper by Dima and Schad, we re-consider the problem of inferring magnetic properties of the corona using polarimetric observations of magnetic dipole (M1) lines. Dima and Schad point to a potential source of degeneracy in a formalism developed by Plowman, which under some circumstances can lead to the solution being under-determined. Here we clarify the nature of the problem. Its resolution lies in solving for the scattering geometry using the elongation of the observed region of the corona. We discuss some conceptual problems that arise when casting the problem for inversion in the observer's reference frame, and satisfactorily resolve difficulties identified by Plowman, Dima and Schad.

Since 1996 the blast wave driven by SN 1987A has been interacting with the dense circumstellar material, which provides us with a unique opportunity to study the early evolution of a newborn supernova remnant (SNR). Based on the XMM-Newton RGS and EPIC-pn X-ray observations from 2007 to 2019, we investigated the post-impact evolution of the X-ray emitting gas in SNR 1987A. The hot plasma is represented by two non-equilibrium ionization components with temperature of $\sim0.6$ keV and $\sim2.5$ keV. The low-temperature plasma has a density $\sim2400$ cm$^{-3}$, which is likely dominated by the lower density gas inside the equatorial ring (ER). The high-temperature plasma with a density $\sim550$ cm$^{-3}$ could be dominated by the H II region and the high-latitude material beyond the ring. In the last few years, the emission measure of the low-temperature plasma has been decreasing, indicating that the blast wave has left the main ER. But the blast wave is still propagating into the high-latitude gas, resulting in the steadily increase of the high-temperature emission measure. In the meantime, the average abundances of N, O, Ne, and Mg are found to be declining, which may reflect the different chemical compositions between two plasma components. We also detected the Fe K lines in most of the observations, showing increasing flux and centroid energy. We interpret the Fe K lines as from a third hot component, which may come from the reflected shock-heated gas or originate from Fe-rich ejecta clumps, shocked by the reverse shock.

A self-similar spherical collapse model predicts a dark matter (DM) splashback and accretion shock in the outskirts of galaxy clusters while misses a key ingredient of structure formation - processes associated with mergers. To fill this gap, we perform simulations of merging self-similar clusters and investigate their DM and gas evolution in an idealized cosmological context. Our simulations show that the cluster rapidly contracts during the major merger and the splashback radius $r_{\rm sp}$ decreases, approaching the virial radius $r_{\rm vir}$. While $r_{\rm sp}$ correlates with a smooth mass accretion rate (MAR) parameter $\Gamma_{\rm s}$ in the self-similar model, our simulations show a similar trend with the total MAR $\Gamma_{\rm vir}$ (includes both mergers and $\Gamma_{\rm s}$). The scatter of the $\Gamma_{\rm vir}-r_{\rm sp}/r_{\rm vir}$ relation indicates a generally low $\Gamma_{\rm s}\sim1$ in clusters in cosmological simulations. In contrast to the DM, the hot gaseous atmospheres significantly expand by the merger-accelerated (MA-) shocks formed when the runaway merger shocks overtake the outer accretion shock. After a major merger, the MA-shock radius is larger than $r_{\rm sp}$ by a factor of up to $\sim1.7$ for $\Gamma_{\rm s}\lesssim1$ and is $\sim r_{\rm sp}$ for $\Gamma_{\rm s}\gtrsim3$. This implies that (1) mergers could easily generate the MA-shock-splashback offset measured in cosmological simulations, and (2) the smooth MAR is small in regions away from filaments where MA-shocks reside. We further discuss various shocks and contact discontinuities formed at different epochs of the merger, the ram pressure stripping in cluster outskirts, and the dependence of member galaxies' splashback feature on their orbital parameters.

The mass accretion rate is the fundamental parameter to understand the process of mass assembly that results in the formation of a low-mass star. This parameter has been largely studied in Classical TTauri stars in star-forming regions with ages of 1-10Myr. However, little is known about the accretion properties of young stellar objects (YSOs) in younger regions and early stages of star formation, such as in the Class0/I phases. We present new NIR spectra of 17 ClassI/Flat and 35 ClassII sources located in the young (<1Myr) NGC1333 cluster, acquired with the KMOS instrument at the VLT. Our goal is to study whether the mass accretion rate evolves with age, as suggested by the widely adopted viscous evolution model, by comparing the properties of the NGC1333 members with samples of older regions. We measured the stellar parameters and accretion rates of our sample, finding a correlation between accretion and stellar luminosity, and between mass accretion rate and stellar mass. Both correlations are compatible within the errors with the older Lupus star-forming region, while only the latter is consistent with results from ChamaeleonI. The ClassI sample shows larger accretion luminosities with respect to the ClassII stars of the same cloud. However, the derived accretion rates are not sufficiently high to build up the inferred stellar masses, assuming steady accretion during the ClassI lifetime. This suggests that the sources are not in their main accretion phase and that most of their mass has already been accumulated during a previous stage and/or that the accretion is an episodic phenomenon. We show that some of the targets originally classified as Class I through Spitzer photometry are in fact evolved or low accreting objects. This evidence can have implications for the estimated protostellar phase lifetimes. Further observations are needed to determine if this is a general result.

Atomic carbon (CI) has been proposed to be a global tracer of the molecular gas as a substitute for CO, however, its utility remains unproven. To evaluate the suitability of CI as the tracer, we performed [CI]$(^3P_1-^3P_0)$ (hereinafter [CI](1-0)) mapping observations of the northern part of the nearby spiral galaxy M83 with the ASTE telescope and compared the distributions of [CI](1-0) with CO lines (CO(1-0), CO(3-2), and $^{13}$CO(1-0)), HI, and infrared (IR) emission (70, 160, and 250$ \mu$m). The [CI](1-0) distribution in the central region is similar to that of the CO lines, whereas [CI](1-0) in the arm region is distributed outside the CO. We examined the dust temperature, $T_{\rm dust}$, and dust mass surface density, $\Sigma_{\rm dust}$, by fitting the IR continuum-spectrum distribution with a single-temperature modified blackbody. The distribution of $\Sigma_{\rm dust}$ shows a much better consistency with the integrated intensity of CO(1-0) than with that of [CI](1-0), indicating that CO(1-0) is a good tracer of the cold molecular gas. The spatial distribution of the [CI] excitation temperature, $T_{\rm ex}$, was examined using the intensity ratio of the two [CI] transitions. An appropriate $T_{\rm ex}$ at the central, bar, arm, and inter-arm regions yields a constant [C]/[H$_2$] abundance ratio of $\sim7 \times 10^{-5}$ within a range of 0.1 dex in all regions. We successfully detected weak [CI](1-0) emission, even in the inter-arm region, in addition to the central, arm, and bar regions, using spectral stacking analysis. The stacked intensity of [CI](1-0) is found to be strongly correlated with $T_{\rm dust}$. Our results indicate that the atomic carbon is a photodissociation product of CO, and consequently, compared to CO(1-0), [CI](1-0) is less reliable in tracing the bulk of "cold" molecular gas in the galactic disk.

The majoron, a neutrinophilic pseudo-Goldstone boson conventionally arising in the context of neutrino mass models, can damp neutrino free-streaming and inject additional energy density into neutrinos prior to recombination. The combination of these effects for an eV-scale mass majoron has been shown to ameliorate the outstanding $H_0$ tension, however only if one introduces additional dark radiation at the level of $\Delta N_{\rm eff} \sim 0.5$. We show here that models of low-scale leptogenesis can naturally source this dark radiation by generating a primordial population of majorons from the decays of GeV-scale sterile neutrinos in the early Universe. Using a posterior predictive distribution conditioned on Planck2018+BAO data, we show that the value of $H_0$ observed by the SH$_0$ES collaboration is expected to occur at the level of $\sim 10\%$ in the primordial majoron cosmology (to be compared with $\sim 0.1\%$ in the case of $\Lambda$CDM). This insight provides an intriguing connection between the neutrino mass mechanism, the baryon asymmetry of the Universe, and the discrepant measurements of $H_0$.

We show that the minimal Type-I Seesaw mechanism can successfully account for the observed dark matter abundance in the form of a keV sterile neutrino. This population can be produced by the decay of the heavier neutral leptons, with masses above the Higgs mass scale, while they are in thermal equilibrium in the early Universe (freeze-in). Moreover, the implementation of the relevant phenomenological constraints (relic abundance, indirect detection and structure formation) on this model automatically selects a region of the parameter space featuring an approximate lepton number symmetry.

In the next decades, ultra-high-energy neutrinos in the EeV energy range will be potentially detected by next-generation neutrino telescopes. Although their primary goals are to observe cosmogenic neutrinos and to gain insight into extreme astrophysical environments, they can also indirectly probe the nature of dark matter. In this paper, we study the projected sensitivity of up-coming neutrino radio telescopes, such as RNO-G, GRAND and IceCube-gen2 radio array, to decaying dark matter scenarios. We investigate different dark matter decaying channels and masses, from $10^7$ to $10^{15}$ GeV. By assuming the observation of cosmogenic or newborn pulsar neutrinos, we forecast conservative constraints on the lifetime of heavy dark matter particles. We find that these limits are competitive with and highly complementary to previous multi-messenger analyses.

This paper aims to study the feasibility of building an Earth-skimming cosmic tau neutrinos detector, with the aim of eventually identifying the ideal dimensions of a natural site (mountainvalley) for the detection, with the energy range to be determined (evidently, the highest possible numbers range from 1015 eV to 1020 eV), and possibly locate one such site in Algeria. First, a Monte Carlo simulation of the neutrino-[mountain]matter interaction as well as the resulting decay of the tau lepton is conducted to determine the optimal dimensions of the mountain as well as the location of the tau decay in the valley. Second, a CORSIKA (COsmic Ray Simulation for KAscade) [1] simulation with the CONEX option is conducted to track the evolution of the almost horizontal air shower born from the tau lepton. Among the particles produced in the shower are: electrons, muons, gammas, pions, etc). The study of the spatial distribution of muons enables the discovery of the optimal width of the valley, and consequently, the distance at which to lay the detection network.

We revisit the possibility of first order electroweak phase transition~(EWPT) in one of the simplest extensions of the Standard Model (SM) scalar sector, namely the two-Higgs-doublet model~(2HDM). We take into account the ensuing constraints from the electroweak precision tests, Higgs signal strengths, and the recent LHC bounds from direct scalar searches. By studying the vacuum transition in 2HDM, we discuss in detail the entropy released in the first order EWPT in various parameter planes of 2HDM.

In recent years, much work have studied the use of convolutional neural networks for gravitational-wave detection. However little work pay attention to whether the transient noise can trigger the CNN model or not. In this paper, we study the responses of the sine-Gaussian glitches, the Gaussian glitches and the ring-down glitches in the trained convolutional neural network classifier. We find that the network is robust to the sine-Gaussian and Gaussian glitches, whose false alarm probabilities are close to that of the LIGO-like noises, in contrast to the case of the ring-down glitches, in which the false alarm probability is far larger than that of the LIGO-like noises. We also investigate the responses of the glitches with different frequency. We find that when the frequency of the glitches falls in that of the trained GW signals, the false alarm probability of the glitches will be much larger than that of the LIGO-like noises, and the probability of the glitches being misjudged as the GW signals may even exceed 30%.

In this paper we consider the massive scalar perturbation on the top of a small spinning-like black hole in context of Einstein-bumblebee modified gravity in order to probe the role of spontaneous Lorentz symmetry breaking on the superradiance scattering and corresponding instability. We show that at the low-frequency limit of the scalar wave the superradiance scattering will be enhanced with the Lorentz-violating parameter $\alpha<0$ and will be weakened with $\alpha>0$. Moreover, by addressing the black hole bomb issue, we extract an improved bound in the instability regime indicating that $\alpha<0$ increases the parameter space of the scalar field instability, while $\alpha>0$ decreases it.

The role of CP-violating decay and annihilation processes have been extensively studied in the context of generating cosmological particle-antiparticle asymmetries, both as sources of the asymmetry and its subsequent wash-out. In the scenarios for which the lowest order source of CP-violation is scattering processes, we highlight the role of additional CP-conserving annihilations in indirectly affecting the asymmetry generation. This stems from the strong dependence of the relevant out-of-equilibrium number densities on the rate of CP-conserving reactions. The net asymmetry generated, in turn, is proportional to the out-of-equilibrium number densities and the rate of CP-violation. Such CP-conserving scatterings occur naturally in scenarios of baryogenesis, leptogenesis and asymmetric dark matter production through scattering, as we illustrate through several examples. We find that the asymmetric yields for relevant particle-antiparticle systems can vary by orders of magnitude depending upon the relative size of the CP-conserving and violating reaction rates.

Metric of axially symmetric asymptotically flat black holes in an arbitrary metric theory of gravity can be represented in the general form which depends on infinite number of parameters. We constrain this general class of metrics by requiring of the existence of additional symmetries, which lead to the separation of variables in the Hamilton-Jacobi and Klein-Gordon equations and show that, once the metric functions change sufficiently moderately in some region near the black hole, the black-hole shadow depends on a few deformation parameters only. We analyze the influence of these parameters on the black-hole shadow. We also show that the shadow of the rotating black hole in the Einstein-dilaton-Gauss-Bonnet theory is well approximated if the terms violating the separation of variables are neglected in the metric.

We simulate numerically the formation of spherically symmetric primordial black holes (PBHs) seeded by different families of primordial curvature perturbations profiles on a Friedman-Robertson-Walker (FRW) Universe filled by radiation fluid. We have studied the dependency on the curvature profile of the initial mass $M_{\rm BH,i}$ of the PBHs at the time of apparent horizon formation $t_{AH}$, and the final mass $M_{\rm BH,f}$ after the accretion process, using an excision technique, comparing $M_{\rm BH,i}$ to previous analytical estimations obtained using compensated PBHs model approach. The analytical estimations are in agreement with numerical results, except for large values of the initial perturbation amplitude, when the compensated model is less accurate. The masses $M_{\rm BH,f}$ and $M_{\rm BH,i}$ do not depend only on the shape around the compaction function peak, but on the full profile of the initial curvature perturbation. We also estimate the accretion effects, and for those PBHs with masses relevant for the dark matter abundance, with a final mass equal to the horizon crossing mass, we find $M_{\rm BH,f}\approx 3 M_{\rm BH,i} $.