Papers for Thursday, Jun 24 2021

Peculiar motion of the solar system, determined from the dipole anisotropy in the Cosmic Microwave Background Radiation (CMBR), has given a velocity $370$ km s$^{-1}$ along RA$=168^{\circ}$, Dec$=-7^{\circ}$. Subsequent peculiar motion determinations from the number counts, sky brightness or redshift dipoles observed in large samples of distant radio galaxies and quasars yielded peculiar velocities two to ten times larger than CMBR, though in all cases the directions matched with the CMBR dipole. Here we introduce a novel technique for determining the peculiar motion from the magnitude-redshift ($m_{\rm B}-z$) Hubble diagram of Type Ia Supernovae (SN Ia), one of the best standard candles available. We find a peculiar velocity $1.6\pm 0.4 \times 10^3$ km s$^{-1}$, about four times larger than the CMBR value, along RA$=173^{\circ}\pm21^{\circ}$, Dec$=10^{\circ}\pm19^{\circ}$, the direction being within $\sim 1\sigma$ of the CMBR dipole. Since a genuine solar motion would not depend upon the method or the dataset employed, large discrepancies seen among various dipole amplitudes could imply that these dipoles, including the CMBR one, might not pertain to observer's peculiar motion. However, a common direction for various dipoles might indicate a preferred direction in the universe, implying an intrinsic anisotropy, in violation of the cosmological principle, a cornerstone of the modern cosmology.

We consider a model where a light scalar field (with mass $\lesssim 30\, {\rm eV}$), conjectured to be dark matter, has a non-minimal coupling to gravity. In the non-relativistic limit, this new coupling introduces a self-interaction term in the scalar-field equation of motion, and modifies the source term for the gravitational field. Moreover, in the small-coupling limit justified by the observed dark-matter density, the system further reduces to the Gross-Pitaevskii-Poisson equations, which remarkably also arise from a self-gravitating and self-interacting Bose-Einstein condensate system. We derive predictions of our model on linear and non-linear structure formation by exploiting this unexpected connection.

The Molecular Ridge in the LMC extends several kiloparsecs south from 30 Doradus, and it contains ~30% of the molecular gas in the entire galaxy. However, the southern end of the Molecular Ridge is quiescent - it contains almost no massive star formation, which is a dramatic decrease from the very active massive star-forming regions 30 Doradus, N159, and N160. We present new ALMA and APEX observations of the Molecular Ridge at a resolution as high as ~16'' (~3.9 pc) with molecular lines 12CO(1-0), 13CO(1-0), 12CO(2-1), 13CO(2-1), and CS(2-1). We analyze these emission lines with our new multi-line non-LTE fitting tool to produce maps of T_kin, n_H2, and N_CO across the region based on models from RADEX. Using simulated data for a range of parameter space for each of these variables, we evaluate how well our fitting method can recover these physical parameters for the given set of molecular lines. We then compare the results of this fitting with LTE and X_CO methods of obtaining mass estimates and how line ratios correspond with physical conditions. We find that this fitting tool allows us to more directly probe the physical conditions of the gas and estimate values of T_kin, n_H2, and N_CO that are less subject to the effects of optical depth and line-of-sight projection than previous methods. The fitted n_H2 values show a strong correlation with the presence of YSOs, and with the total and average mass of the associated YSOs. Typical star formation diagnostics, such as mean density, dense gas fraction, and virial parameter do not show a strong correlation with YSO properties.

Large-scale stellar surveys coupled with recent developments in magneto-hydrodynamical simulations of the formation of Milky Way-mass galaxies provide an unparalleled opportunity to unveil the physical processes driving the evolution of the Galaxy. We developed a framework to compare a variety of parameters with their corresponding predictions from simulations in an unbiased manner, taking into account the selection function of a stellar survey. We applied this framework to a sample of over 7000 stars with asteroseismic, spectroscopic, and astrometric data available, together with 6 simulations from the Auriga project. We found that some simulations are able to produce abundance dichotomies in the $[{\rm Fe}/{\rm H}]-[\alpha/{\rm Fe}]$ plane which look qualitatively similar to observations. The peak of their velocity distributions match the observed data reasonably well, however they predict hotter kinematics in terms of the tails of the distributions and the vertical velocity dispersion. Assuming our simulation sample is representative of Milky Way-like galaxies, we put upper limits of 2.21 and 3.70 kpc on radial migration for young ($< 4$ Gyr) and old ($\in [4, 8]$ Gyr) stellar populations in the solar cylinder. Comparison between the observed and simulated metallicity dispersion as a function of age further constrains migration to about 1.97 and 2.91 kpc for the young and old populations. These results demonstrate the power of our technique to compare numerical simulations with high-dimensional datasets, and paves the way for using the wider field TESS asteroseismic data together with the future generations of simulations to constrain the subgrid models for turbulence, star formation and feedback processes.

Upcoming measurements of the 21-cm line of neutral hydrogen will open a new observational window into the early stages of structure growth, providing a unique opportunity for probing large-scale cosmological signatures using the small-scale signals from the first stars. In this paper we evaluate the detection significance of compensated isocurvature perturbations (CIPs) from observations of the 21-cm hydrogen-line during the cosmic-dawn era. CIPs are modulations of the relative baryon and dark-matter density that leave the total matter density unchanged. We find that, under different assumptions for feedback and foregrounds, the ongoing HERA and upcoming SKA1-low experiments will provide constraints on uncorrelated CIPs at the level of $\sigma(A_{\rm CIP})= 10^{-3}-10^{-4}$, comparable to the sensitivity of upcoming CMB experiments, and potentially exceeding the constraints from cosmic-variance limited BAO surveys.

We present results from \textsc{GigaEris}, a cosmological, $N$-body hydrodynamical ``zoom-in'' simulation of the formation of a Milky Way-sized galaxy with unprecedented resolution, encompassing of order a billion particles within the refined region. The simulation employs a modern implementation of smoothed-particle hydrodynamics, including metal-line cooling and metal and thermal diffusion. We focus on the early assembly of the galaxy, down to redshift $z=4.4$. The simulated galaxy has properties consistent with extrapolations of the main sequence of star-forming galaxies to higher redshifts and levels off to a star formation rate of $\sim$60$\, M_{\odot}$yr$^{-1}$ at $z=4.4$. A compact, thin rotating stellar disk with properties analogous to those of low-redshift systems arises already at $z \sim 8$-9. The galaxy rapidly develops a multi-component structure, and the disk, at least at these early stages, does not grow upside-down as often reported in the literature. Rather, at any given time, newly born stars contribute to sustain a thin disk, while the thick disk grows from stars that are primarily added through accretion and mergers. The kinematics reflect the early, ubiquitous presence of a thin disk, as a stellar disk component with $v_\phi/\sigma_R$ larger than unity is already present at $z \sim 9$-10. Our results suggest that high-resolution spectro-photometric observations of very high-redshift galaxies should find thin rotating disks, consistent with the recent discovery of cold rotating gas disks by ALMA. Finally, we present synthetic images for the JWST NIRCam camera, showing how the early disk would be easily detectable already at $z \sim 7$.

This paper uses Gaussian mixture techniques to dissect the Milky Way (MW) stellar halo in angular momentum space. Application to a catalogue of 5389 stars near the plane of the Sagittarius (Sgr) stream with full 6D phase-space coordinates supplied by Gaia EDR3 and SEGUE returns four independent dynamical components. The broadest and most populated corresponds to the `smooth' MW halo. The narrowest and faintest contains 40 stars of the Orphan stream. We find a component with little or no angular momentum likely associated with the GSE substructure. We also identify 925 stars and 7 Globular Clusters with probabilities $>90\%$ to be members of the Sgr stream. Comparison against $N$-body models shows that some of these members trace the continuation of the leading/trailing tails in the Southern/Northern hemispheres. The new detections span $\sim 800^\circ$ on the sky, thus wrapping the Galaxy {\it twice}.

This paper provides a catalogue of stars, quasars, and galaxies for the Southern Photometric Local Universe Survey Data Release 2 (S-PLUS DR2) in the Stripe 82 region. We show that a 12-band filter system (5 Sloan-like and 7 narrow bands) allows better performance for object classification than the usual analysis based solely on broad bands (regardless of infrared information). Moreover, we show that our classification is robust against missing values. Using spectroscopically confirmed sources retrieved from the Sloan Digital Sky Survey DR16 and DR14Q, we train a random forest classifier with the 12 S-PLUS magnitudes + 4 morphological features. A second random forest classifier is trained with the addition of the W1 (3.4 $\mu$m) and W2 (4.6 $\mu$m) magnitudes from the Wide-field Infrared Survey Explorer (WISE). Forty-four percent of our catalogue have WISE counterparts and are provided with classification from both models. We achieve 95.76% (52.47%) of quasar purity, 95.88% (92.24%) of quasar completeness, 99.44% (98.17%) of star purity, 98.22% (78.56%) of star completeness, 98.04% (81.39%) of galaxy purity, and 98.8% (85.37%) of galaxy completeness for the first (second) classifier, for which the metrics were calculated on objects with (without) WISE counterpart. A total of 2,926,787 objects that are not in our spectroscopic sample were labelled, obtaining 335,956 quasars, 1,347,340 stars, and 1,243,391 galaxies. From those, 7.4%, 76.0%, and 58.4% were classified with probabilities above 80%. The catalogue with classification and probabilities for Stripe 82 S-PLUS DR2 is available for download.

The traditional core accretion model of giant planet formation, developed from 1D quasi-static models, has been challenged by the discovery of recycling flows between the planetary envelope and the disc that can slow or stall envelope accretion. We carry out 3D radiation hydrodynamic simulations with an updated opacity compilation to model the proto-Jupiter's envelope. To isolate the 3D effects of convection and recycling, we simulate both isolated spherical envelopes and envelopes embedded in discs. The envelopes are heated at given rates to achieve steady states, enabling comparisons with 1D models. We vary envelope properties to obtain both radiative and convective solutions. Using a passive scalar, we observe significant mass recycling on the orbital timescale. For a radiative envelope, recycling can only penetrate to $\sim$0.1-0.2 Hill radii, while for a convective envelope, the convective motion can ``dredge up'' the deeper part of the envelope so that the entire simulated envelope is recycled efficiently. This recycling, however, has only limited effects on the envelopes' thermal structure. The radiative envelope embedded in the disc has identical structures as the isolated envelope. The convective envelopes are also similar, following the adiabatics, except for a slightly higher density when the envelope is embedded in a disc. We introduce a modified 1D approach which can fully reproduce our 3D simulations in both the radiative and convective limits. With our updated opacity, equation of states, and 1D models, we recompute Jupiter's envelope accretion with a 10 $M_{\oplus}$ core. Consistent with prior work, the timescale to runaway accretion is shorter than the disc lifetime.

We carried out new CO($J$ = 2-1) observations toward the mixed-morphology supernova remnant (SNR) W49B with the Atacama Large Millimeter/submillimeter Array (ALMA). We found that CO clouds at $\sim$10 km s$^{-1}$ show a good spatial correspondence with synchrotron radio continuum as well as an X-ray deformed shell. The bulk mass of molecular clouds accounts for the western part of the shell, not for the eastern shell where near-infrared H$_2$ emission is detected. The molecular clouds at $\sim$10 km s$^{-1}$ show higher kinetic temperature of $\sim$20-60 K, suggesting that modest shock-heating occurred. The expanding motion of the clouds with $\Delta V \sim$6 km s$^{-1}$ was formed by strong winds from the progenitor system. We argue that the barrel-like structure of Fe rich ejecta was possibly formed not only by an asymmetric explosion, but also by interactions with dense molecular clouds. We also found a negative correlation between the CO intensity and the electron temperature of recombining plasma, implying that the origin of the high-temperature recombining plasma in W49B can be understood as the thermal conduction model. The total energy of accelerated cosmic-ray protons $W_\mathrm{p}$ is estimated to be $\sim$$2\times 10^{49}$ erg by adopting an averaged gas density of $\sim$$650\pm200$ cm$^{-3}$. The SNR age-$W_\mathrm{p}$ diagram indicates that W49B shows one of the highest in-situ values of $W_\mathrm{p}$ in the gamma-ray bright SNRs.

We present an analysis of a new 120 deg$^{2}$ radio continuum image of the Large Magellanic Cloud (LMC) at 888 MHz with a bandwidth of 288 MHz and beam size of $13\rlap{.}^{\prime\prime}9\times12\rlap{.}^{\prime\prime}1$, from the Australian Square Kilometre Array Pathfinder (ASKAP) processed as part of the Evolutionary Map of the Universe (EMU) survey. The median Root Mean Squared noise is 58 $\mu$Jy beam$^{-1}$. We present a catalogue of 54,612 sources, divided over a GOLD list (30,866 sources) complete down to 0.5 mJy uniformly across the field, a SILVER list (22,080 sources) reaching down to $<$ 0.2 mJy and a BRONZE list (1,666 sources) of visually inspected sources in areas of high noise and/or near bright complex emission. We discuss detections of planetary nebulae and their radio luminosity function, young stellar objects showing a correlation between radio luminosity and gas temperature, novae and X-ray binaries in the LMC, and active stars in the Galactic foreground that may become a significant population below this flux level. We present examples of diffuse emission in the LMC (H II regions, supernova remnants, bubbles) and distant galaxies showcasing spectacular interaction between jets and intracluster medium. Among 14,333 infrared counterparts of the predominantly background radio source population we find that star-forming galaxies become more prominent below 3 mJy compared to active galactic nuclei. We combine the new 888 MHz data with archival Australia Telescope Compact Array data at 1.4 GHz to determine spectral indices; the vast majority display synchrotron emission but flatter spectra occur too. We argue that the most extreme spectral index values are due to variability.

We report on the analysis of a deep Chandra observation of the high-magnetic field pulsar (PSR) J1119-6127 and its compact pulsar wind nebula (PWN) taken in October 2019, three years after the source went into outburst. The 0.5-7 keV post-outburst (2019) spectrum of the pulsar is best described by a two-component blackbody plus powerlaw model with a temperature of 0.2\pm0.1 keV, photon index of 1.8\pm0.4 and X-ray luminosity of ~1.9e33 erg s^{-1}, consistent with its pre-burst quiescent phase. We find that the pulsar has gone back to quiescence. The compact nebula shows a jet-like morphology elongated in the north-south direction, similar to the pre-burst phase. The post-outburst PWN spectrum is best fit by an absorbed powerlaw with a photon index of 2.3\pm0.5 and flux of ~3.2e-14 erg cm^{-2} s^{-1} (0.5-7 keV). The PWN spectrum shows evidence of spectral softening in the post-outburst phase, with the pre-burst photon index of 1.2\pm0.4 changing to 2.3\pm0.5, and pre-burst luminosity of ~1.5e32 erg s^{-1} changing to 2.7e32 erg s^{-1} in the 0.5-7 keV band, suggesting magnetar outbursts can impact PWNe. The observed timescale for returning to quiescence, of just a few years, implies a rather fast cooling process and favors a scenario where J1119 is temporarily powered by magnetic energy following the magnetar outburst, in addition to its spin-down energy.

The afterglow of GRB~190114C has been observed at {60-1200~s} after the burst in the {sub-TeV range} by the {MAGIC Cherenkov} telescope. The simultaneous observations in X-ray range, which is presumed to be of synchrotron origin, and in sub-TeV range, where the emission is presumed to be inverse Compton, provide new stringent constraints on the conditions within the emitting regions {and their evolution in time}. While the additional data contain a lot of new information, it turns out that fitting both the X-ray and the TeV emission, is much more complicated than what was originally anticipated. We find that optical flux measurements provide important complementary information that in combination with TeV measurements breaks degeneracy in the parameter space. We present here a numerical fit to the multi-wavelength observed spectrum using a new code that calculates the single-zone synchrotron including self-Compton emission taking into account the exact Klein-Nishina cross-sections as well as pair production via absorption of the high-energy photons inside the emitting zone and the emission from the resulting secondary pairs. We also present a revised set of single zone parameters and a method for fitting the data to the observations. Our model for GRB~190114C that fits all the observations, from the optical data point to the sub-TeV range, suggests that it is in the fast cooling regime. The inferred parameters for observations {at two separate moments of time} show significant deviations from some of the common expectations in afterglow modeling but are all consistent with the predictions of the {pair-balance} model.

We present a comprehensive statistical analysis of 106 sheath regions driven by coronal mass ejections (CMEs) and measured near 1 AU. Using data from the STEREO probes, this extended analysis focuses on two discrete categorizations. In the first categorization, we investigate how the generic features of sheaths change with their potential formation mechanisms (propagation and expansion sheaths), namely, their associations with magnetic ejectas (MEs) which are primarily expanding or propagating in the solar wind. We find propagation sheaths to be denser and driven by stronger MEs, whereas expansion sheaths are faster. Exploring the temporal profiles of these sheaths with a superposed epoch technique, we observe that most of the magnetic field and plasma signatures are more elevated in propagation sheaths relative to expansion sheaths. The second categorization is based on speed variations across sheaths. Employing linear least squares regression, we categorize four distinct speed profiles of the sheath plasma. We find that the associated shock properties and solar cycle phase do not impact the occurrence of such variations. Our results also highlight that the properties of the driving MEs are a major source of variability in the sheath properties. Through logistic regression, we conclude that the magnetic field strength and the ME speed in the frame of the solar wind are likely drivers of these speed variations.

Nereid, Neptune's third largest satellite, lies in an irregular orbit and is the only outer satellite in the system (apart from Triton) that can be spectroscopically characterized with the current generation of Earth-based telescopes. We report our results on spectral characterization of Nereid using its reflectance spectrum from 0.8-2.4 $\mu m$, providing the first measurements over the range of 0.8-1.4 $\mu m$. We detect spectral absorption features of crystalline water ice in close agreement with previous measurements. We show that model fits of simple intimate mixtures including water ice do not provide simultaneous matches to absorption band depths at 1.5 and 2.0 $\mu m$ when accounting for the spectral continuum. Possible solutions include invoking a more complex continuum, including both crystalline and amorphous water ice, and allowing for sub-micron sized grains. We show that mixtures including magnetite and the CM2 chondrite Murchison provide a flexible framework for interpreting spectral variation of bodies with neutral-sloped spectra like that of Nereid. Magnetite in particular provides a good match to the spectral continuum without requiring the presence of Tholin-like organics. We note that carbonaceous chondrites and their components may be useful analogs for the non-ice components of outer solar system bodies, consistent with recent findings by Fraser et al. (2019). Comparison to spectra of large TNOs and satellites of Uranus show that Nereid's low albedo, deep water bands, and neutral color is distinct from many other icy objects, but such comparisons are limited by incomplete understanding of spectral variability among $\sim$100km-sized icy bodies.

We present the Heraklion Extragalactic Catalogue, or HECATE, an all-sky value-added galaxy catalogue, aiming to facilitate present and future multi-wavelength and multi-messenger studies in the local Universe. It contains 204,733 galaxies up to a redshift of 0.047 (D<200 Mpc), and it is >50% complete in terms of the B-band luminosity density at distances in the 0-170 Mpc range. By incorporating and homogenising data from astronomical databases and multi-wavelength surveys, the catalogue offers positions, sizes, distances, morphological classifications, star-formation rates, stellar masses, metallicities, and nuclear activity classifications. This wealth of information can enable a wide-range of applications, such as: (i) demographic studies of extragalactic sources, (ii) initial characterisation of transient events, and (iii) searches for electromagnetic counterparts of gravitational-wave events. The catalogue is publicly available to the community at a dedicated portal, which will also host future extensions in terms of the covered volume, and data products.

The tension between current expansion rate H$_0$ using Planck data and direct model-independent measurements in the local universe has reached a tension above 5$\sigma$ in the context of the $\Lambda$CDM model. The growing tension among early time and local measurements of H$_0$ has not ameliorated and remains a crucial and open question in cosmology. Solutions to understand this tension are possible hidden sources of systematic error in the observable measurements or modifications to the concordance $\Lambda$CDM model. In this work, we investigate a solution to the H$_0$ tension by modifying $\Lambda$CDM and we add at early times extra relativistic energy density $\rho_{ex}$. In some context this $\rho_{ex}$ corresponds to EDE or Bound Dark Energy. We implement our model in CAMB and perform a full COSMO-MC (MCMC) allowing to simultaneously fit the latest data from CMB anisotropies and the value of H$_0 = 74.03\pm 1.42,\mathrm{km\, s^{-1}Mpc^{-1}}$ from A. Riess [R-19] \ci{Riess:2019cxk}. The inclusion of $\rho_{ex}$ ameliorates the tension between early and late time measurements only slightly and we obtain a value H$_0 = (68.70\pm 0.45$\ksm) still in conflict with local measurements [R-19]. We follow up our analysis by proposing two forecasting standard deviation $\sigma_H=1$ and $\sigma_H=0.5$ (in units of \ksm) for local distance measurements H$_0 = (74.03\pm \sigma_H)$ \ksm. From MCMC we obtain a value of H$_0 =(72.83\pm 0.47)$ \ksm\, at 68\% confidence level for $\sigma_H =0.5$, fully consistent with [R-19], while the price to pay is a percentage increase of $0.12\%$ in CMB $\chi_{cmb}^2$. Finally, the extra energy density $\rho_{ex}$ leaves distinctive imprints in the matter power spectrum at scales $k \sim k_c$ with $k_c=a_cH(a_c)$ and in the CMB power spectrum, allowing for independent verification of our analysis.

We present a multi-wavelength photometric and spectroscopic analysis of thirteen ``Super-Chandrasekhar Mass"/2003fg-like type Ia Supernova (SNe Ia). Nine of these objects were observed by the Carnegie Supernova Project. 2003fg-like SNe have slowly declining light curves ($\Delta m_{15}$(B) $<$1.3 mag), and peak absolute B-band magnitudes between -19 $< M_{B} <$ -21 mag. Many 2003fg-like SNe are located in the same part of the luminosity width relation as normal SNe Ia. In the optical B and V bands, 2003fg-like SNe look like normal SNe Ia, but at redder wavelengths they diverge from normal objects. Unlike other luminous SNe Ia, 2003fg-like SNe generally have only one i-band maximum which peaks after the epoch of B-band maximum, while their NIR light curve rise times can be $>$40 days longer than those of normal SNe Ia. They are also at least one magnitude brighter in the NIR bands than normal SNe Ia, peaking above $M_{H}<$ -19 mag, and generally have negative Hubble residuals. Spectroscopically, 2003fg-like SNe exhibit peculiarities such as unburnt carbon well past maximum light, a large spread (8000-12000 km s$^{-1}$) in Si II $\lambda$6355 velocities at maximum light with no rapid early velocity decline, no clear H-band break at +10d, and low ionization lines in the nebular phase. We find that SNe with a larger pseudo equivalent width of C II at maximum light have lower Si II $\lambda$6355 velocities and slower declining light curves. There are also multiple factors that contribute to the peak luminosity of 2003fg-like SNe. The explosion of a C-O degenerate core inside a carbon-rich envelope is consistent with these observations. Such a configuration may come from the core degenerate scenario.

The classical nova V2491 Cyg was once suggested to be a recurrent nova. We have broadly reproduced the light curve of V2491 Cyg by a nova outburst model on a cold $1.36~M_\odot$ white dwarf (WD), which strongly suggests that V2491 Cyg is a classical nova outbursting on a cold very massive WD rather than a recurrent nova outbursting on a warmer WD like the recurrent nova RS Oph. In a long-term evolution of a cataclysmic binary, an accreting WD has been settled down to a thermal equilibrium state with the balance of gravitational energy release and neutrino loss. The central temperature of the WD is uniquely determined by the energy balance. The WD is hot (cold) for a high (low) mass-accretion rate. We present the central temperatures, ignition masses, ignition radii, and recurrence periods for various WD masses and mass-accretion rates. In a classical nova, which corresponds to a low mass-accretion rate, the WD is cool and strongly degenerated and the ignition mass is large, which result in a strong nova outburst. In a recurrent nova, the WD is relatively warmer because of a high mass accretion rate and the outburst is relatively weaker. The gravitational energy release substantially contributes to the luminosity during the recurrent nova outbursts. We compare physical properties between classical novae and recurrent novae and discuss the essential differences between them.

The Large Area Telescope (LAT), the primary instrument for the Fermi Gamma-ray Space Telescope (Fermi) mission, is an imaging, wide field-of-view, high-energy gamma-ray telescope, covering the energy range from 30 MeV to more than 300 GeV. We describe the performance of the instrument at the 10-year milestone. LAT performance remains well within the specifications defined during the planning phase, validating the design choices and supporting the compelling case to extend the duration of the Fermi mission. The details provided here will be useful when designing the next generation of high-energy gamma-ray observatories.

We present the analysis of a sample of \ha\,, \hb\ and \oii\ emission line galaxies from the \otelo\ survey, with masses typically below $log(M_*/M_\sun) \sim 9.4$ and redshifts between $z \sim 0.4$ and 1.43. We study the star formation rate, star formation rate density, and number density and their evolution with redshift. We obtain a robust estimate of the specific star formation rate -- stellar mass relation based on the lowest mass sample published so far. We also determine a flat trend of the star formation rate density and number density with redshift. Our results suggest a scenario of no evolution of the number density of galaxies, regardless of their masses, up to redshift $z\sim1.4$. This implies a gradual change of the relative importance of the star forming processes, from high-mass galaxies to low-mass galaxies, with decreasing redshift. We also find little or no variation of the star formation rate density in the redshift range of $0.4<z<1.43$.

Recent observational and theoretical studies indicate that the damping of solar coronal loop oscillations depends on the oscillation amplitude. We consider two mechanisms, linear resonant absorption and a nonlinear damping model. We confront theoretical predictions from these models with observed data in the plane of observables defined by the damping ratio and the oscillation amplitude. The structure of the Bayesian evidence in this plane displays a clear separation between the regions where each model is more plausible relative to the other. There is qualitative agreement between the regions of high marginal likelihood and Bayes factor for the nonlinear damping model and the arrangement of observed data. A quantitative application to 101 loop oscillation cases observed with SDO/AIA results in the marginal likelihood for the nonlinear model being larger in the majority of them. The cases with conclusive evidence for the nonlinear damping model outnumber considerably those in favor of linear resonant absorption.

The production spectrum of high-energy muons as a function of depth in the atmosphere is relevant for understanding properties of event rates in deep detectors. For a given atmospheric profile, cascades of heavy nuclei develop at higher altitude than proton showers, giving rise to larger separation of muons at depth. For a given type of primary cosmic ray, seasonal variations in muon rates reflect the fact that higher temperatures correspond to lower densities and to a relative increase in the ratio of decay to re-interaction of the parent mesons. In this paper, we present a generalization of the Elbert formula that tracks meson decay to muons along the trajectory of the primary cosmic-ray nucleus. The convolution of the production spectrum with a changing atmospheric profile provides the dependence of event rates and sizes of muon bundles on temperature and primary mass. We consider applications to IceCube and also to multiple muon events in the compact underground detectors of MINOS and the NOvA Near Detector.

Context. Binary evolution can result in fast-rotating stars, predicted to be observable as Be stars, through accretion of angular momen- tum during mass-transfer phases. Despite numerous observational evidence pointing to this possibly being the dominant Be formation channel, current models struggle to produce a satisfactory description of Be star populations. Aims. Given distinct uncertainties in detailed binary evolution calculations, we investigate a rigorous and model independent upper limit for the production of Be stars through binary interaction and aim to confront this limit with observations of Be stars in young star clusters. Methods. Using extreme assumptions, we calculate the number ratio of post-interaction to pre-interaction binary systems in a coeval population, which describes an upper limit to Be star formation through mass-transfer. A detailed comparison is made between our derived upper limit and relevant observations of Be stars, which allows us to probe several aspects of binary star physics. Results. We find that in coeval populations, binary interaction can at most account for one third of all main-sequence stars being Be stars. Near the cluster turn-off region, this limit appears to be realised in the clusters studied. Away from the turn-off, applying simple assumptions about which systems undergo unstable mass-transfer produces a good fit to the observed Be fraction as a function of mass. Conclusions. We find that assuming distinct physics, binary evolution alone can in principle match the high numbers of Be stars observed in open clusters. Whether the required binary physics is realised in nature remains to be investigated.

Galaxy clusters have been found to host a range of diffuse, non-thermal emission components, generally with steep, power law spectra. In this work we report on the detection and follow-up of radio halos, relics, remnant radio galaxies, and other fossil radio plasmas in Southern Sky galaxy clusters using the Murchison Widefield Array, Australian Square Kilometre Array Pathfinder. We make use of the frequency coverage between the two radio interferometers - from 88 to $\sim 900$ MHz - to characterise the integrated spectra of these sources within this frequency range. Highlights from the sample include the detection of a double relic system in Abell 3186, a mini-halo in RXC J0137.2-0912, a candidate halo and relic in Abell 3399, and a complex multi-episodic head-tail radio galaxy in Abell 3164. We compare this selection of sources and candidates to the literature sample, finding sources consistent with established radio power-cluster mass scaling relations. Finally, we use the low-frequency integrated spectral index, $\alpha$ ($S_\nu \propto \nu^\alpha$), of the detected sample of cluster remnants and fossil sources to compare with samples of known halos, relics, remnants and fossils to investigate a possible link between their electron populations. We find the distributions of $\alpha$ to be consistent with relic and halo emission generated by seed electrons that originated in fossil or remnant sources. However, the present sample sizes are insufficient to rule out other scenarios.

Black hole imaging challenges the 3rd generation space VLBI, the Very Long Baseline Interferometry, to operate on a 500 GHz band. The coherent integration timescale needed here is of 450 s though the available space oscillators cannot offer more than 10 s. Self-calibration methods might solve this issue in an interferometer formed by 3 antenna/satellite system, but the need in the 3rd satellite increases mission costs. A frequency transfer is of special interest to alleviate both performance and cost issues. A concept of 2-way optical frequency transfer is examined to investigate its suitability to enable space-to-space interferometry, in particular, to image the 'shadows' of black holes from space. The concept, promising on paper, has been demonstrated by tests. The laboratory test set-up is presented and the verification of the temporal stability using standard analysis tool as TimePod is given. The resulting Allan Deviation is dominated by the 1/$\tau$ phase noise trend since the frequency transfer timescale of interest is shorter than 0.2 s. This trend continues into longer integration times, as proven by the longest tests spanning over a few hours. The Allan Deviation between derived 103.2 GHz oscillators is $1.1\times10^{-14}/\tau$ within 10 ms < $\tau$ < 1,000 s that degrades twice towards the longest delay 0.2 s. The worst case satisfies the requirement with a margin of an order of magnitude. The obtained coherence in range of 0.997-0.9998 is beneficial for space VLBI at 557 GHz. The result is of special interest to future science missions for black hole imaging from space.

The real-time recognition of neutrino signals from astrophysical objects with very-low false alarm rate and short-latency, is crucial to perform multi-messenger detection, especially in the case of distant core-collapse supernovae accessible with the next generation of large-scale neutrino telescopes. The current time-based selection algorithms implemented in operating online monitors depend mainly on the number of events (multiplicity) detected in a fixed time window, under the hypothesis of Poisson-distributed background. However, these methods are not capable of exploiting the time profile discrepancies between the expected supernova neutrino burst and the stationary background. In this paper we propose a new general and flexible technique (beta filter method) which provides specific decision boundaries on the cluster multiplicity-duration plane, guaranteeing the desired false alarm rate in an analytical way. The performance is evaluated using the injection of a general purpose SN-like signal on top of realistic background rates in current detectors. An absolute gain in efficiency of up to $\sim 80\%$ is achieved compared with the standard techniques, and a new ultra-low multiplicity region is unveiled.

Recently the LHAASO Collaboration published the detection of 12 ultra-high-energy gamma-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV gamma rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy gamma rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^5 times the Planck scale M_{pl} and that the second-order LIV scale is >10^{-3}M_{pl}. Both limits improve by at least one order of magnitude the previous results.

Retrieval of exoplanetary atmospheric properties from their transmission spectra commonly assumes that the errors in the data are Gaussian and independent. However, non-Gaussian noise can occur due to instrumental or stellar systematics and merging discrete datasets. We investigate the effect of correlated noise and constrain the potential biases incurred in the retrieved posteriors. We simulate multiple noise instances of synthetic data and perform retrievals to obtain statistics of goodness-of-retrieval for varying noise models. We find that correlated noise allows for overfitting the spectrum, thereby yielding better goodness-of-fit on average but degrading the overall accuracy of retrievals. In particular, correlated noise can manifest as an apparent non-Rayleigh slope in the optical range, leading to an incorrect estimate of cloud/haze parameters. We also find that higher precision causes correlated results to be further off from the input values in terms of estimated errors. As such, we emphasize that caution must be taken in analyzing retrieved posteriors and that estimated parameter uncertainties are best understood as lower limits. Finally, we show that while correlated noise cannot be be reliably distinguished with HST observations, inferring its presence and strength may be possible with JWST observations.

We report on an unusually bright observation of PSR J2051$-$0827 recorded during a regular monitoring campaign of black-widow pulsar systems with the Effelsberg 100-m telescope. Through fortunate coincidence, a particularly bright scintillation maximum is simultaneous with the eclipse by the companion, enabling precise measurements of variations in the flux density, dispersion measure (DM), and scattering strength throughout the eclipse. The flux density is highly variable throughout the eclipse, with a peak 1.7 times the average away from the eclipse, and yet does not significantly decrease on average. We recover the flux density variations from the measured DM variations using geometric optics, with a relative velocity as the only free parameter. We measure an effective velocity of 470 $\pm$ 10 km/s, consistent with the relative orbital motion of the companion, suggesting that the outflow velocity of the lensing material is low, or is directly along the line-of-sight. The 2% uncertainty on the effective velocity is a formal error; systematics related to our current model are likely to dominate, and we detail several extensions to the model to be considered in a full treatment of lensing. This is a demonstration of the causal link between DM and lensing; the flux density variations can be predicted directly through the derivatives of DM. Going forward, this approach can be applied to investigate the dynamics of other eclipsing systems, and to investigate the physical nature of scintillation and lensing in the ionized interstellar medium.

The detection of the unusually heavy binary neutron star merger GW190425 marked a stark contrast to the mass distribution from known Galactic millisecond pulsars in neutron star binaries and gravitational-wave source GW170817. We suggest here a formation channel for heavy binary neutron stars in which massive helium stars, assembled after common envelope, remain compact and avoid mass transfer onto the neutron star companion and thus evade pulsar recycling. In particular we present three-dimensional simulations of the supernova explosion of the massive stripped helium star and follow the mass fallback evolution and the subsequent accretion onto the neutron star companion. We find that fallback leads to significant mass growth in the newly formed neutron star and that the companion does not accrete sufficient mass to become a millisecond pulsar. This can explain the formation of heavy binary neutron star systems such as GW190425, as well as predict the assembly of neutron star - light black hole systems. Moreover, this hints to the existence of a sizable population of radio-quiet double compact objects in our Galaxy. Finally, this formation avenue is consistent with the observed mass-eccentricity correlation of binary neutron stars in the Milky Way.

We measure the projected half-light radii of young star clusters in 31 galaxies from the Legacy Extragalactic UV Survey (LEGUS). We implement a custom pipeline specifically designed to be robust against contamination, which allows us to measure radii for 6097 clusters. This is the largest sample of young star cluster radii currently available. We find that most (but not all) galaxies share a common cluster radius distribution, with the peak at around 3 pc. We find a clear mass-radius relation of the form $R_{\mathrm{eff}} \propto M^{0.24}$. This relation is present at all cluster ages younger than 1 Gyr, but with a shallower slope for clusters younger than 10 Myr. We present simple toy models to interpret these age trends, finding that high-mass clusters are more likely to be not tidally limited and expand. We also find that most clusters in LEGUS are gravitationally bound, especially at older ages or higher masses. Lastly, we present the cluster density and surface density distributions, finding a large scatter that appears to decrease with cluster age. The youngest clusters have a typical surface density of 100 $M_\odot$ pc$^{-2}$.

We study inflation with the most general non-degenerate gravitational action that depends on the symmetric part of the Ricci tensor coupled to a scalar field in the Palatini formulation of gravity. We use field redefinitions to shift the effect of the Ricci terms from gravity to the scalar field, and apply the result to slow-roll inflation. As examples, we consider actions quadratic and cubic in the Ricci tensor. In the quadratic case the results are similar to the case $R+\alpha R^2$ that has been studied earlier: the tensor-to-scalar ratio $r$ can be suppressed by an arbitrary amount, while the scalar spectrum is unaffected. In the cubic case, $r$ can be suppressed by at most a factor of $2/9$, and the change in the scalar spectral index $n_s$ can be large.

Here we present new - and, nevertheless, last - mid-infrared (mid-IR) data for supernovae (SNe) based on measurements with the Spitzer Space Telescope. Comparing our recent 3.6 and 4.5 $\mu$m photometry with previously published mid-IR and further multiwavelength datasets, we were able to draw some conclusions about the origin and heating mechanism of the dust in these SNe or in their environments, as well as on possible connection with circumstellar matter (CSM) originating from pre-explosion mass-loss events in the progenitor stars. We also present new results regarding both certain SN classes and single objects. We highlight the mid-IR homogeneity of SNe Ia-CSM, which may be a hint of their common progenitor type and of their basically uniform circumstellar environments. Regarding single objects, it is worth highlighting the late-time interacting Type Ib SNe 2003gk and 2004dk, for which we present the first-ever mid-IR data, which seem to be consistent with clues of ongoing CSM interaction detected in other wavelength ranges. Our current study suggests that long-term mid-IR follow-up observations play a key role in a better understanding of both pre- and post-explosion processes in SNe and their environments. While Spitzer is not available any more, the expected unique data from the James Webb Space Telescope, as well as long-term near-IR follow-up observations of dusty SNe, can bring us closer to the hidden details of this topic.

Context: Galaxy interactions and mergers can lead to supermassive black hole (SMBH) binaries which become active galactic nuclei (AGN) pairs when the SMBHs start accreting mass. If there is a third galaxy involved in the interaction, then a triple AGN system can form. Aims: Our goal is to investigate the nature of the nuclear emission from the galaxies in the interacting pair NGC\,7733--NGC\,7734 using archival VLT/MUSE Integral field spectrograph data and study its relation to the stellar mass distribution traced by near-infrared (NIR) observations from the South African Astronomical Observatory (SAAO). Methods:We conducted near-infrared observations using the SAAO and identified the morphological properties of bulges in each galaxy. We used MUSE data to obtain a set of ionized emission lines from each galaxy and studied the ionization mechanism. We also examined the relation of the galaxy pair with any nearby companions with Far-UV observations using the UVIT. Conclusions: The emission line analysis from the central regions of NGC\,7733 and NGC\,7734 show Seyfert and LINER type AGN activity. The galaxy pair NGC\,7733--34 also shows evidence of a third component, which has Seyfert-like emission. Hence, the galaxy pair NGC\,7733--34 forms a triple AGN system. We also detected an Extended Narrow-line region (ENLR) associated with the nucleus of NGC\,7733.

ESA's INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) was launched on 17 Oct 2002 at 06:41 CEST. Since then, it has been providing long, uninterrupted observations (up to about 47 hr, or 170 ksec, per satellite orbit of 2.7 days) with a large field-of-view (fully coded: 100 deg^2), msec time resolution, keV energy resolution, polarization measurements, as well as additional coverage in the optical. This is realized by two main instruments in the 15 keV to 10 MeV range, the spectrometer SPI (spectral resolution 3 keV at 1.8 MeV) and the imager IBIS (angular resolution 12 arcmin FWHM), complemented by X-ray (JEM-X; 3-35 keV) and optical (OMC; Johnson V-band) monitors. All instruments are co-aligned to simultaneously observe the target region. A particle radiation monitor (IREM) measures charged particle fluxes near the spacecraft. The Anti-coincidence subsystems of the main instruments are also efficient all-sky gamma-ray detectors, which provide omni-directional monitoring above ~75 keV. INTEGRAL can also rapidly (within a couple of hours) re-point and conduct Target of Opportunity observations. INTEGRAL has build an impressive legacy: e.g. discovery of >600 new high-energy sources; first-ever direct detection of 56Ni and 56Co radio-active decay lines from a Type Ia supernova; new insights on positron annihilation in the Galactic bulge and disk; pioneering gamma-ray polarization studies. INTEGRAL is also a successful in multi-messenger astronomy: INTEGRAL found the first prompt electromagnetic radiation in coincidence with a binary neutron star merger. More than 1750 papers based on INTEGRAL data have been published in refereed journals. Here we give a comprehensive update of the satellite status after more than 18 years of operations in a harsh space environment, and an account of the successful Ground Segment.

Clouds are expected to form in a wide range of conditions in the atmosphere of exoplanets given the large range of possible condensible species. However this diversity might lead to very different small-scale dynamics depending on radiative transfer in various thermal conditions: we aim at providing some insights into these dynamical regimes. We perform an analytical linear stability analysis of a compositional discontinuity with a heating source term that depends on composition. We also perform idealized two-dimensional (2D) simulations of an opacity discontinuity in a stratified medium with the code ARK. We use a two-stream grey model for radiative transfer and explore the brown-dwarf and earth-like regimes. We reveal the existence of a Radiative Rayleigh-Taylor Instability (RRTI hereafter, a particular case of diabatic Rayleigh-Taylor instability) when an opacity discontinuity is present in a stratified medium. This instability is similar in nature to diabatic convection and relies only on buoyancy with radiative transfer heating and cooling. When the temperature is decreasing with height in the atmosphere, a lower-opacity medium on top of a higher-opacity medium is dynamically unstable while a higher-opacity medium on top of a lower-opacity medium is stable. This stability/instability behavior is reversed if the temperature is increasing with height. The existence of the RRTI could have important implications for the stability of the cloud cover of a wide range of planetary atmospheres. In our solar system, it could help explain the formation of mammatus cloud in Earth atmospheres and the existence of Venus cloud deck. Likewise, it suggests that stable and large scale cloud covers could be ubiquitous in strongly irradiated exoplanets but might be more patchy in low-irradiated or isolated objects like brown dwarfs and directly imaged exoplanets.

Narrow-line Seyfert 1 (NLS1) galaxies are a class of active galactic nuclei (AGN) that, in some cases, can harbor powerful relativistic jets. One of them, PKS 2004-447, shows gamma-ray emission, and underwent its first recorded multifrequency flare in 2019. However, past studies revealed that in radio this source can be classified as a compact steep-spectrum source (CSS), suggesting that, unlike other gamma-ray sources, the relativistic jets of PKS 2004-447 have a large inclination with respect to the line of sight. We present here a set of spectroscopic observations of this object, aimed at carefully measuring its black hole mass and Eddington ratio, determining the properties of its emission lines, and characterizing its long term variability. We find that the black hole mass is $(1.5\pm0.2)\times10^7$ M$_\odot$, and the Eddington ratio is 0.08. Both values are within the typical range of NLS1s. The spectra also suggest that the 2019 flare was caused mainly by the relativistic jet, while the accretion disk played a minor role during the event. In conclusion, we confirm that PKS 2004-447 is one of the rare examples of gamma-ray emitting CSS/NLS1s hybrid, and that these two classes of objects are likely connected in the framework of AGN evolution.

Following the collapse of their cores, some of the massive binary stars that populate our Universe are expected to form merging binaries composed of black holes and neutron stars. Gravitational-wave observations of the resulting compact binaries can reveal precious details on the inner workings of the supernova mechanism and the subsequent formation of compact objects. Within the framework of the population-synthesis code MOBSE, we present the implementation of a new supernova model that relies on the compactness of the collapsing star. The model has two free parameters, namely the compactness threshold that separates the formation of black holes and that of neutron stars, and the fraction of the envelope that falls back onto the newly formed black holes. We compare this model extensively against other prescriptions that are commonly used in binary population synthesis. We find that the cleanest signatures of the role of the pre-supernova stellar compactness are (i) the relative formation rates of the different kinds of compact binaries, which mainly depend on the compactness threshold parameter, and (ii) the location of the upper edge of the mass gap between the lightest black holes and the heaviest neutron stars, which mainly depends on the fallback fraction.

In this work we study how to employ the upcoming Legacy Survey of Space and Time (LSST) data to constrain physical properties of normal, star forming galaxies. We use simulated LSST data and existing real observations to test the estimations of the physical properties of galaxies, such as star formation rate (SFR), stellar mass ($M_{star}$), and dust luminosity ($L_{dust}$). We focus on normal star-forming galaxies, as they form the majority of the galaxy population in the universe and therefore are more likely to be observed by the LSST. We perform a simulation of LSST observations and uncertainties of 50,385 real galaxies within redshift range $0<z<2.5$. In order to achieve this goal, we used the unique multi-wavelength data from the Herschel Extragalactic Legacy Project (HELP) survey. Our analysis focus on two fields: ELAIS-N1 and COSMOS. To obtain galaxy physical properties we fit their Spectral Energy Distributions (SEDs) using the Code Investigating GALaxy Emission (CIGALE). We compare the main galaxy physical properties obtained from the fit of the observed multi-wavelength photometry of galaxies (from UV to FIR) to the ones obtained from the simulated LSST optical measurements only. The stellar masses estimated based on the LSST measurements are in agreement with the full UV-FIR SED estimations, as they depend mainly on the UV and optical emission, well covered by LSST in the considered redshift range. We obtain a clear overestimation of SFR, $L_{dust}$, $M_{dust}$ estimated with LSST only, highly correlated with redshift. We investigate the cause of this overestimation and we conclude that it is related to an overestimation of the dust attenuation, both UV and NIR. We find that it is necessary to employ auxiliary rest-frame mid-infrared observations, simulated UV observations, or FUV attenuation (AFUV)- Mstar relation, to correct the overestimation.

While the LCDM framework has been incredibly successful for modern cosmology, it requires the admission of two mysterious substances as a part of the paradigm, dark energy and dark matter. Although this framework adequately explains most of the large-scale properties of the Universe (i.e., existence and structure of the CMB, the large-scale structure of galaxies, the abundances of light elements and the accelerating expansion), it has failed to make significant predictions on smaller scale features such as the kinematics of galaxies and their formation. In particular, the rotation curves of disk galaxies (the original observational discovery of dark matter) are better represented by non-Newtonian models of gravity that challenge our understanding of motion in the low acceleration realm (much as general relativity provided an extension of gravity into the high acceleration realm e.g., blackholes). The tension between current cold dark matter scenarios and proposed new formulations of gravity in the low energy regime suggests an upcoming paradigm shift in cosmology. And, if history is a guide, observations will lead the way.

We propose a new mechanism for baryogenesis, in which baryon asymmetry is generated by absorption of a new particle $X$ carrying baryon number onto Primordial Black Holes (PBHs). Due to CP violation of $X$ and $\overline{X}$ scattering with the plasma surrounding PBHs, the two conjugate particles are differently absorbed by PBHs, leading to the production of an asymmetry in the $X$ sector. The production is halted by PBH evaporation, after which the asymmetry is transferred into the baryonic sector via $X$ decay. We show that this mechanism can produce the correct amount of asymmetry without violating the known constraints on PBHs concentration. Furthermore, we provide a systematic study of the parameter space, identifying the regions leading to the production of the correct baryon asymmetry.

The lepton flavour asymmetries of the Universe are observationally almost unconstrained before the onset of neutrino oscillations. We calculate the cosmic trajectory during the cosmic QCD epoch in the presence of large lepton flavour asymmetries. By including QCD thermodynamic quantities derived from functional QCD methods in our calculation our work reveals for the first time the possibility of a first-order cosmic QCD transition. We specify the required values of the lepton flavour asymmetries for which a first-order transition occurs for a number of different benchmark scenarios.

We propose a new method for discriminating sub-micron nuclear recoil tracks from an instrumental background in fine-grain nuclear emulsions used in the directional dark matter search. The proposed method is based on the Deep Learning approach and uses a 3D Convolutional Neural Network architecture with parameters optimised by Bayesian search. Unlike previous studies focused on extracting the directional information, we focus on the signal/background separation exploiting the polarisation dependence of the Localised Surface Plasmon Resonance phenomenon. Comparing the proposed method with the conventional cut-based approach shows a significant boost in the rejection power while keeping the signal efficiency at the same level.

The performance of on telescope depend strongly on its operating conditions. During pointing the telescope can move at a relatively high velocity, and the system can tolerate trajectory position errors higher than during tracking. On the contrary, during tracking Alt-Az telescopes generally move slower but still in a large dynamic range. In this case, the position errors must be as close to zero as possible. Tracking is one of the essential factors that affect the quality of astronomical observations. In this paper, a hybrid Genetic-Fuzzy approach to control the movement of a two-link direct-drive Celestron telescope is introduced. The proposed controller uses the Genetic algorithm (GA) for optimizing a fuzzy logic controller (FLC) to improve the tracking of the 14-inches Celestron telescope of the Kottamia Astronomical Observatory (KAO). The fuzzy logic input is a vector of the position error and its rate of change, and the output is torque. The GA objective function used here is the Integral Time Absolute Error (ITAE). The proposed method is compared with a conventional Proportional-Differential (PD) controller, an optimized PD controller with a GA, and a Fuzzy controller. The results show the effectiveness of the proposed controller to improve the dynamic response of the overall system.

The abundance of light nuclei and hyperons, that are produced in stellar environments such as supernova or binary mergers, is calculated within a relativistic mean-field model with density dependent couplings in low-density matter. Five light nuclei are considered, together with three light hyper-nuclei. We show that the presence of hyperons shifts the dissolution of clusters to larger densities, and increases the amount of clusters. This effect is larger the smaller the charge fraction, and the higher the temperature. The abundance of hyperons is also affected by the cluster formation: neutral and positively charged hyperons suffer a reduction, and the negatively charged ones an increase. We also observe that the dissolution of the less-abundant clusters occurs at larger densities due to smaller Pauli-blocking effects. Overall, hyper-nuclei set in at temperatures above 25 MeV, and depending on the temperature and chemical composition, they may be more abundant than $\alpha$-particles, or even more abundant than other heavier clusters.

In previous papers, explicit symplectic integrators were designed for nonrotating black holes, such as a Schwarzschild black hole. However, they fail to work in the Kerr spacetime because not all variables can be separable, or not all splitting parts have analytical solutions as explicit functions of proper time. To cope with this difficulty, we introduce a time transformation function to the Hamiltonian of Kerr geometry so as to obtain a time-transformed Hamiltonian consisting of five splitting parts, whose analytical solutions are explicit functions of the new coordinate time. The chosen time transformation function can cause time steps to be adaptive, but it is mainly used to implement the desired splitting of the time transformed Hamiltonian. In this manner, new explicit symplectic algorithms are easily available. Unlike Runge Kutta integrators, the newly proposed algorithms exhibit good long term behavior in the conservation of Hamiltonian quantities when appropriate fixed coordinate time steps are considered. They are better than same order implicit and explicit mixed symplectic algorithms and extended phase space explicit symplectic like methods in computational efficiency. The proposed idea on the construction of explicit symplectic integrators is suitable for not only the Kerr metric but also many other relativistic problems, such as a Kerr black hole immersed in a magnetic field, a Kerr Newman black hole with an external magnetic field, axially symmetric core shell systems, and five dimensional black ring metrics.

AMIGO - The Astrodynamical Middle-frequency Interferometric GW (Gravitation-Wave) Observatory is a first-generation mid-frequency GW mission bridging the sensitivity gap between the high-frequency GW detectors and low-frequency space GW detectors. In our previous works, we have obtained appropriate heliocentric orbit formations of nominal arm length 10,000 km with their first-generation time-delay configurations satisfying frequency noise reduction requirement, and we have also worked out thrust-fuel friendly constant-arm heliocentric orbit formations. In this paper, we review and study noise requirements and present the corresponding GW sensitivities. From the design white position noises and acceleration noises, we obtain the GW sensitivities for the first-generation Michelson X TDI configuration of b-AMIGO (baseline AMIGO), AMIGO, and e-AMIGO (enhanced AMIGO). In view of the current technology development, we study and indicate steps to implement the AMIGO mission concept.

A small fraction of the gravitational-wave (GW) signals that will be detected by second and third generation detectors are expected to be strongly lensed by galaxies and clusters, producing multiple observable copies. While optimal Bayesian model selection methods are developed to identify lensed signals, processing tens of thousands (billions) of possible pairs of events detected with second (third) generation detectors is both computationally intensive and time consuming. To mitigate this problem, we propose to use machine learning to rapidly rule out a vast majority of candidate lensed pairs. As a proof of principle, we simulate non-spinning binary black hole events added to Gaussian noise, and train the machine on their time-frequency maps (Q-transforms) and localisation skymaps (using Bayestar), both of which can be generated in seconds. We show that the trained machine is able to accurately identify lensed pairs with efficiencies comparable to existing Bayesian methods.

Magnetic reconnection can convert magnetic energy into kinetic energy of non-thermal electron beams. We have now characterized the EVDFs generated by 3D kinetic magnetic reconnection obtained by numerical simulations utilizing the ACRONYM particle-in-cell (PIC) code, and their consequences for plasma instabilities which differ from those of 2D kinetic magnetic reconnection, since in 3D unstable waves can propagate in all directions. We found that: (1) In both diffusion region and separatrices of reconnection, EVDFs with positive velocity-space gradients in the direction parallel to the local magnetic field are formed. These gradients can cause counter-streaming and bump-on-tail instabilities. (2) In regions with weak magnetic field strength, namely, regions near the current sheet midplane, EVDF with positive velocity space gradients are generated in the direction perpendicular to the local magnetic field. In particular crescent-shaped EVDFs in the velocity space perpendicular to local magnetic field are mainly formed in the diffusion region of reconnection. These perpendicular gradients in the EVDFs can cause electron cyclotron maser instabilities. (3) As guide-field strength increases, less regions in the current sheets feature perpendicular velocity-space gradients in the EVDFs. The formation of EVDFs with positive gradients in the parallel (magnetic field-aligned) direction is mainly due to magnetized and adiabatic electrons, while EVDFs with positive gradients in the direction perpendicular to the local magnetic field are attributed to unmagnetized, nonadiabatic electrons in the diffusion and outflow region near the reconnection midplane.

The measurement of the epicyclic frequencies is a widely used astrophysical technique to infer information on a given self-gravitating system and on the related gravity background. We derive their explicit expressions in static and spherically symmetric wormhole spacetimes. We discuss how these theoretical results can be applied to: (1) detect the presence of a wormhole, distinguishing it by a black hole; (2) reconstruct wormhole solutions through the fit of the observational data, once we have them. Finally, we discuss the physical implications of our proposed epicyclic method.