Papers for Tuesday, Feb 08 2022

The kilonova (KN) associated with the binary neutron star (BNS) merger GW170817 is the only known electromagnetic counterpart to a gravitational wave source. Here we produce a sequence of radiative transfer models (using \textsc{tardis}) with updated atomic data, and compare them to accurately calibrated spectra. We use element compositions from nuclear network calculations based on a realistic hydrodynamical simulation of a BNS merger. We show that the blue spectrum at +1.4 days after merger requires a nucleosynthetic trajectory with a high electron fraction. Our best-fitting model is composed entirely of first $r$-process peak elements (Sr \& Zr) and the strong absorption feature is reproduced well by Sr\,\textsc{ii} absorption. At this epoch, we set an upper limit on the lanthanide mass fraction of $X_{\textrm{LN}} \lesssim 5 \times 10^{-3}$. In contrast, all subsequent spectra from $+2.4 - 6.4$ days require the presence of a modest amount of lanthanide material ($X_{\textrm{LN}} \simeq 0.05^{+0.05}_{-0.02}$), produced by a trajectory with $Y_{\rm e} = 0.29$. This produces lanthanide-induced line blanketing below 6000\,\AA, and sufficient light $r$-process elements to explain the persistent strong feature at $\sim 0.7 - 1.0$\,\micron\ (Sr\,\textsc{ii}). The composition gives good matches to the observed data, indicating that the strong blue flux deficit results in the near-infrared (NIR) excess. The disjoint in composition between the first epoch and all others indicates either ejecta stratification, or the presence of two distinct components of material. This further supports the `two-component' kilonova model, and constrains the element composition from nucleosynthetic trajectories. The major uncertainties lie in availability of atomic data and the ionisation state of the expanding material.

We determine the error introduced in a joint halo model analysis of galaxy-galaxy lensing and galaxy clustering observables when adopting the standard approximation of linear halo bias. Considering the Kilo-Degree Survey, we forecast that ignoring the non-linear halo bias would result in up to 5$\sigma$ offsets in the recovered cosmological parameters describing structure growth, $S_8$, and the matter density parameter, $\Omega_{\mathrm{m}}$. The direction of these offsets are shown to depend on the freedom afforded to the halo model through other nuisance parameters. We conclude that a beyond-linear halo bias correction must therefore be included in future cosmological halo model analyses of large-scale structure observables on non-linear scales.

The halo assembly bias, a phenomenon referring to dependencies of the large-scale bias of a dark matter halo other than its mass, is a fundamental property of our standard cosmological model. First discovered in 2005 via high-resolution numerical simulations, it has been proven very difficult to be detected observationally, with only a few convincing claims of detection thus far. The main obstacle lies in finding an accurate proxy of the halo formation time. In this study, by utilizing a constrained simulation that can faithfully reproduce the observed structures larger than ~ 2 Mpc in the local universe, for a sample of about 630 massive clusters at ${z \leq 0.12}$, we find their counterpart halos in the simulation and use the mass growth history of the matched halos to estimate the formation time of the observed clusters. This allows us to construct a pair of early- and late-forming clusters, with similar mass as measured via weak gravitational lensing, and large-scale bias differing at at least $4{\sigma}$ level, implying a detection of assembly bias.

We present a catalog of stellar companions to host stars of TESS Objects of Interest (TOIs) identified from a marginalized likelihood ratio test that incorporates astrometric data from the Gaia Early Data Release 3 catalog (EDR3). The likelihood ratio is computed using a probabilistic model that incorporates parallax and proper motion covariances and marginalizes the distances and 3D velocities of stars in order to identify comoving stellar pairs. We find 172 comoving companions to 170 non-false positive TOI hosts, consisting of 168 systems with two stars and 2 systems with three stars. Amongst the 170 TOI hosts, 54 harbor confirmed planets that span a wide range of system architectures. We conduct an investigation of the mutual inclinations between the stellar companion and planetary orbits using Gaia EDR3, which is possible because transiting exoplanets must orbit within the line-of-sight, thus stellar companion kinematics can constrain mutual inclinations. While the statistical significance of the current sample is weak, we find that 73$^{+14}_{-20}\%$ of systems with Kepler-like architectures ($R_{P}$ $\leq$ 4 $R_\oplus$ and $a$ $<$ 1 AU) appear to favor a non-isotropic orientation between the planetary and companion orbits with a typical mutual inclination $\alpha$ of 35 $\pm$ 24$^\circ$. In contrast, 65$^{+20}_{-35}\%$ of systems with close-in giants ($P$ $<$ 10 days and $R_{P}$ $>$ 4 $R_{\oplus}$) favor a perpendicular geometry ($\alpha =$ 89 $\pm$ 21$^\circ$) between the planet and companion. Moreover, the close-in giants with large stellar obliquities (planet-host misalignment) are also those that favor significant planet-companion misalignment.

The observation of quasars at high redshifts presents a mystery in the theory of black hole formation. In order to source such objects, one often relies on the presence of heavy seeds ($M \approx 10^{4-6} \, M_{\odot}$) in place at early times. Unfortunately, the formation of these heavy seeds are difficult to realize within the standard astrophysical context. Here, we investigate whether superconducting cosmic string loops can source sufficiently strong overdensities in the early universe to address this mystery. We review a set of direct collapse conditions under which a primordial gas cloud will undergo monolithic collapse into a massive black hole (forming with a mass of $M_{BH} \approx 10^5 \, M_{\odot}$ at $z \approx 300$ in our scenario), and systematically show how superconducting cosmic string loops can satisfy such conditions in regions of the $G\mu-I$ parameter space.

There is overwhelming geological evidence from 60Fe and 244Pu isotopes that Earth was in direct contact with the interstellar medium (ISM) 2-3 Myr ago. The local interstellar medium is home to several nearby cold clouds. Here we show that if the solar system passed through a cloud such as Local Leo Cold Cloud, then the heliosphere which protects the solar system from interstellar particles, had shrunk to a scale smaller than the Earth's orbit around the Sun $(0.22~AU)$. Using a magnetohydrodynamic simulation that includes charge exchange between neutral atoms and ions, we show that during the heliosphere shrinkage, Earth was exposed to a neutral hydrogen density of up to $3000cm^{-3}$. This could have had drastic effects on Earth's climate and potentially of human evolution at that time, as suggested by previous data.

After the successful detection of cosmic high-energy neutrinos, the field of multiwavelength photon studies of active galactic nuclei (AGN) is entering an exciting new phase. The first hint of a possible neutrino signal from the blazar TXS 0506+056 leads to the anticipation that AGN could soon be identified as point sources of high-energy neutrino radiation, representing another messenger signature besides the well-established photon signature. To understand the complex flaring behavior at multiwavelengths, a genuine theoretical understanding needs to be developed. These observations of the electromagnetic spectrum and neutrinos can only be interpreted fully when the charged, relativistic particles responsible for the different emissions are modeled properly. The description of the propagation of cosmic rays in a magnetized plasma is a complex question that can only be answered when analysing the transport regimes of cosmic rays in a quantitative way. In this paper, we therefore present a quantitative analysis of the propagation regimes of cosmic rays in the approach that is most commonly used to model non-thermal emission signatures from blazars, i.e. the existence of a high-energy cosmic-ray population in a relativistic plasmoid traveling along the jet axis. In this paper, we show that in the considered energy range of high-energy photon and neutrino emission, the transition between diffusive and ballistic propagation takes place, significantly influencing not only the spectral energy distribution but also the lightcurve of blazar flares.

The study of binary neutron stars mergers by the detection of the emitted gravitational waves is one of the most promised tools to study the properties of dense nuclear matter at high densities. It is worth claiming that, at the moment, strong evidence that the temperature of the stars is zero during the last orbits before coalescing, does not exist. Nevertheless, theoretical studies suggest that the temperature concerning the inspiral phase, could reach even a few MeV. According to the main theory, tides transfer mechanical energy and angular momentum to the star at the expense of the orbit, where friction within the star converts the mechanical energy into heat. During the inspiral, these effects are potentially detectable. Different treatments have been used to estimate the transfer of the mechanical energy and the size of the tidal friction, leading to different conclusions about the importance of pre-merger tidal effects. The present work is dedicated to the study of the effect of temperature on the tidal deformability of neutron stars during the inspiral of a neutron star system just before the merger. We applied a class of hot equations of state, both isothermal and adiabatic, originated from various nuclear models. We found that even for low values of temperature ($T<1$ MeV), the effects on the basic ingredients of tidal deformability are not negligible. On the other hand, in the case of the adiabatic star, the thermal effects on tidal deformability remain imperceptible, up to the value $S=0.2 \ {\rm k}_{B}$. According to the main finding, the effect of the temperature on the tidal deformability is indistinguishable. The consequences of the above result are discussed and analyzed.

We study the impact of an Upwind scheme on the numerical convergence of simulations of the Hall and Ohmic effect in neutron stars crusts. While simulations of these effects have explored a variety of geometries and wide ranges of physical parameters, they are limited to relatively low values of the Hall parameter, playing the role of the magnetic Reynolds number, which should be not exceed a few hundred for numerical convergence. We study the evolution of the magnetic field in a plane-parallel Cartesian geometry. We discretise the induction equation using a finite difference scheme and then integrate it via the Euler forward method. Two different approaches are used for the integration of the advective terms appearing in the equation: a Forward Time and Central in Space (FTCS) and an Upwind scheme. We compare them in terms of accuracy and performance. We explore the impact of the Upwind method on convergence according to the ratio of planar to vertical field and the Hall parameter. In the limit of a low strength planar field the use of an Upwind scheme provides a vast improvement leading to the convergence of simulations where the Hall parameter is 2 orders of magnitude higher than that of the FTCS. Upwind is still better if the planar field is stronger, yet, the difference of the maximum value of the Hall parameter reached is within a factor of 10 or a few. Moreover, we notice if the schemes diverge their behaviour is very different, with FTCS producing infinite energy, while the Upwind scheme only temporarily increasing the overall magnetic field energy. Overall, the Upwind scheme enhances the efficiency of the simulations allowing the exploration of environments with higher value of electric conductivity getting us closer than before to realistic environmental conditions of magnetars.

The data volumes stored in telescope archives is constantly increasing due to the development and improvements in the instrumentation. Often the archives need to be stored over a distributed storage architecture, provided by independent compute centres. Such a distributed data archive requires overarching data management orchestration. Such orchestration comprises of tools which handle data storage and cataloguing, and steering transfers integrating different storage systems and protocols, while being aware of data policies and locality. In addition, it needs a common Authorisation and Authentication Infrastructure (AAI) layer which is perceived as a single entity by end users and provides transparent data access. The scientific domain of particle physics also uses complex and distributed data management systems. The experiments at the Large Hadron Collider\,(LHC) accelerator at CERN generate several hundred petabytes of data per year. This data is globally distributed to partner sites and users using national compute facilities. Several innovative tools were developed to successfully address the distributed computing challenges in the context of the Worldwide LHC Computing Grid (WLCG). The work being carried out in the ESCAPE project and in the Data Infrastructure for Open Science (DIOS) work package is to prototype a Scientific Data Lake using the tools developed in the context of the WLCG, harnessing different physics scientific disciplines addressing FAIR standards and Open Data. We present how the Scientific Data Lake prototype is applied to address astronomical data use cases. We introduce the software stack and also discuss some of the differences between the domains.

Interstellar dust is a key physical ingredient of galaxies, obscuring star formation, regulating the heating and cooling of the gas, and building-up chemical complexity. In this manuscript, I give a wide review of interstellar dust properties and some of the modern techniques used to study it. I start with a general introduction presenting the main concepts, in molecular and solid-state physics, required to understand the contemporary literature on the subject. I then review the empirical evidence we currently use to constrain state-of-the-art dust models. Follows a long discussion about our current understanding of the grain properties of nearby galaxies, with an emphasis on the results from spectral energy distribution modeling. The following chapter presents dust evolution at all scales. I review the different microphysical evolution processes, and the way they are accounted for in cosmic dust evolution models. I give my take on the origin of interstellar dust in galaxies of different metallicities. The last chapter focusses on methodology. I give an introduction to the Bayesian method and compare it to frequentist techniques. I discuss the epistemological consequences of the two approaches, and show why the field of interstellar dust requires a probabilistic viewpoint. I end the manuscript with a summary of the major breakthroughs achieved in the past decade, and delineate a few prospectives for the next decade.

We present the analysis of five black hole (BH) candidates identified from gravitational microlensing surveys. HST astrometric data and densely sampled lightcurves from ground-based microlensing surveys are fit with a single-source, single-lens microlensing model in order to measure the mass and luminosity of each lens and determine if it is a black hole. One of the five targets (OGLE-2011-BLG-0462/MOA-2011-BLG-191 or OB110462 for short) shows a significant $>1$ mas coherent astrometric shift, little to no lens flux, and has an inferred lens mass of 1.6 - 4.2 $M_\odot$. This makes OB110462 the first definitive discovery of a compact object through astrometric microlensing and it is most likely either a neutron star or a low-mass black hole. This compact object lens is relatively nearby (690 - 1370 pc) and has a slow transverse motion of $<$ 25 km/s. OB110462 shows significant tension between models well-fit to photometry vs. astrometry, making it currently difficult to distinguish between a neutron star and a black hole. Additional observations and modeling with more complex system geometries, such as binary sources are needed to resolve the puzzling nature of this object. For the remaining four candidates, the lens masses are $<2 M_\odot$ and they are unlikely to be black holes; but two of the four are likely white dwarfs or neutron stars. We compare the full sample of 5 candidates to theoretical expectations on the number ($\sim 10^8$) of BHs in the Milky Way and find reasonable agreement given the small sample size.

The precessing jet-nozzle scenario has been applied to interpret the VLBI-kinematics of twenty-seven superluminal components in blazar 3C345 measured during an about 38-yr period. The superluminal knots could be ejected from a double jet-nozzle system forming a double-jet structure.Both nozzles could precess with a period of about 7.30yr and in the same direction.For both jets a steady precessing common trajectory could exist, along which different knots moved according to their precession phases. Most knots were model-simulated to be accelerated with their bulk Lorentz factor in the range of about 4 to 30 and their Lorentz/Doppler factor profiles were derived. The radio light-curves of knot C9 were well coincident with its Doppler boosting profile. The double precessing nozzle scenario has been applied to interpret the VLBI-kinematics for four blazars (3C279, OJ287, 3C454.3 and 3C345). The charateristic parameters of the four putative supermassive black hole binaries (including hole masses, orbital separation and gravitational radiation lifetime, etc.) were derived and compared, showing that they are in physically reasonable ranges, and well consistent with some theoretical arguments for close black hole binaries.

Radio pulsar glitches probe far-from-equilibrium processes involving stress accumulation and relaxation in neutron star interiors. Previous studies of glitch rates have focused on individual pulsars with as many recorded glitches as possible. In this work we analyze glitch rates using all available data including objects that have glitched never or once. We assume the glitch rate follows a homogeneous Poisson process, and therefore exclude pulsars which exhibit quasiperiodic glitching behavior. Calculating relevant Bayes factors shows that a model in which the glitch rate $\lambda$ scales as a power of the characteristic age $\tau$ is preferred over models which depend arbitrarily on powers of the spin frequency $\nu$ and/or its time derivative $\dot{\nu}$. For $\lambda = A (\tau/\tau\vref)^{-\gamma}$, where $\tau_{\rm ref}=1\ {\rm yr}$ is a reference time, the posterior distributions are unimodal with $A=\ModelAAglitch\ \rm{yr}^{-1}$, and $\gamma=\ModelAgammaglitch$. Importantly, the data exclude with 99\% confidence the possibility $\gamma=1$ canvassed in the literature. When objects with zero recorded glitches are included, the age-based rate law is still preferred and the posteriors change to give $A=\ModelAAall\ \rm{yr}^{-1}$, and $\gamma=\ModelAgammaall$. The updated estimates still support increased glitch activity for younger pulsars, while demonstrating that the large number of objects with zero glitches contain important statistical information about the rate, provided that they are part of the same population as opposed to a disjoint population which never glitches for some unknown physical reason.

We present the first ever discovery of a short-period and unusually helium-deficient dwarf nova KSP-OT-201701a by the Korea Microlensing Telescope Network Supernova Program. The source shows three superoutbursts, each led by a precursor outburst, and several normal outbursts in BVI during the span of ~2.6 years with supercycle and normal cycle lengths of about 360 and 76 days, respectively. Spectroscopic observations near the end of a superoutburst reveal the presence of strong double-peaked HI emission lines together with weak HeI emission lines. The helium-to-hydrogen intensity ratios measured by HeI{\lambda}5876 and H{\alpha} lines are 0.10 {\pm} 0.01 at a quiescent phase and 0.26 {\pm} 0.04 at an outburst phase, similar to the ratios found in long-period dwarf novae while significantly lower than those in helium cataclysmic variables (He CVs). Its orbital period of 51.91 {\pm} 2.50 minutes, which is estimated based on time series spectroscopy, is a bit shorter than the superhump period of 56.52 {\pm} 0.19 minutes, as expected from the gravitational interaction between the eccentric disk and the secondary star. We measure its mass ratio to be 0.37^{+0.32}_{-0.21} using the superhump period excess of 0.089 {\pm} 0.053. The short orbital period, which is under the period minimum, the unusual helium deficiency, and the large mass ratio suggest that KSP-OT-201701a is a transition object evolving to a He CV from a long-period dwarf nova with an evolved secondary star.

The measurement of the apsidal motion in close eccentric massive binary systems provides essential information to probe the internal structure of the stars that compose the system. Following the determination of the fundamental stellar and binary parameters, we make use of the tidally induced apsidal motion to infer constraints on the internal structure of the stars composing the binary system HD152219. The extensive set of spectroscopic, photometric, and radial velocity observations allows us to constrain the fundamental parameters of the stars together with the rate of apsidal motion of the system. Stellar structure and evolution models are further built with the Cl\'es code testing different prescriptions for the internal mixing occurring inside the stars. The effect of stellar rotation axis misalignment with respect to the normal to the orbital plane on our interpretation of the apsidal motion in terms of internal structure constants is investigated. Made of an O9.5 III primary star (M1 = 18.64+/-0.47M${_\odot}$, R1 = 9.40+0.14-0.15R${_\odot}$, Teff,1 = 30900+/-1000 K) and a B1-2 V-III secondary star (M2 = 7.70+/-0.12M${_\odot}$, R2 = 3.69+/-0.06R${_\odot}$, Teff,2 = 21697+/-1000 K), the binary system HD152219 displays apsidal motion at a rate (1.198+/-0.300){\deg}yr-1. The weighted-average mean of the internal structure constant of the binary system is inferred: k2 = 0.00173+/-0.00052. For the Cl\'es models to reproduce the k2-value of the primary star, a significant enhanced mixing is required, notably through the turbulent mixing, but at the cost that other stellar parameters cannot be reproduced simultaneously. The difficulty to reproduce the k2-value simultaneously with the stellar parameters as well as the incompatibility between the age estimates of the primary and secondary stars are indications that some physics of the stellar interior are still not completely understood.

Ultra-massive white dwarfs (UMWDs) with masses larger than 1.05Msun are basically believed to harbour oxygen-neon (ONe) cores. Recently, Gaia data reveals an enhancement of UMWDs on Hertzsprung-Russell diagram (HRD), which indicates that extra cooling delay mechanism such as crystallization and elemental sedimentation may exist in the UMWDs. Further studies suggested that a portion of UMWDs should have experienced pretty long cooling delays, implying that they are carbon-oxygen (CO) WDs. However, the formation mechanism of these UMCOWDs is still under debate. In this work, we investigated whether the merges of massive CO WDs with helium WDs (He WDs) can evolve to UMCOWDs. By employing stellar evolution code MESA, we construct double WD merger remnants to investigate their final fates. We found that the post-merger evolution of the remnants are similar to R CrB stars. The helium burning of the He shell leads to the mass growing of the CO core at a rate from 2.0*10^-6 to 5.0*10^-6 Msun/yr . The final CO WD mass is influenced by the wind-mass-loss rate during the post-merger evolution, and cannot exceed about 1.2Msun. The remnants with core mass larger than 1.2Msun will experience surface carbon ignition, which may finally end their lives as ONe WDs. Current results implies that at least a portion of UMWDs which experience extra long cooling delay may stem from merging of CO WDs and He WDs.

Extreme temperature contrasts between the day and nightside of ultra-hot Jupiters result in significantly asymmetric atmospheres, with a large expansion occurring over a small range of longitude around the terminator. Over the course of a transit, WASP-76b rotates by about 30 degree, changing the observable part of the atmosphere and invoking variations in the appearance of its constituents. As recently reported, this results in time-variable effects in the neutral iron signal, which are amplified by its possible condensation on the nightside. Here, we study the presence of molecular signals during a transit of WASP-76b observed with the CARMENES spectrograph and compare the contributions from this planet's morning and evening terminators. The results are somewhat puzzling, with formal detections of water vapor (5.5$\sigma$) and hydrogen cyanide (5.2$\sigma$) but at significantly different positions in the K$_p$-V$_{sys}$ diagram, with a blueshift of -14.3 $\pm$ 2.6 km/s and a redshift of $+$20.8 $^{+7.8}_{-3.9}$ km/s respectively, and a higher K$_p$ than expected. The H$_2$O signal also appears stronger later on in the transit, in contrast to that of HCN, which seems stronger early on. We tentatively explain this by silicate clouds forming and raining out on the nightside, partially removing oxygen from the upper atmosphere. For C/O values between 0.7 and 1, this leads to the formation of HCN at the morning limb. At the evening terminator, with the sequestered oxygen being returned to the gas phase due to evaporation, these C/O values lead to formation of H$_2$O instead of HCN. If confirmed, these results indicate that individual molecules trace different parts of the atmosphere, as well as nightside condensation, allowing spatial characterization. As these results are based on a single transit, we advocate that more data are needed to confirm them and further explore these scenarios.

The evolution of white dwarfs is essentially a gravothermal process of cooling in which the basic ingredients for predicting their evolution are well identified, although not always well understood. There are two independent ways to test the cooling rate. One is the luminosity function of the white dwarf population, and another is the secular drift of the period of pulsation of those individuals that experience variations. Both scenarios are sensitive to the cooling or heating time scales, for which reason, the inclusion of any additional source or sink of energy will modify these properties and will allow to set bounds to these perturbations. These studies also require complete and statistical significant samples for which current large data surveys are providing an unprecedented wealth of information. In this paper we review how these techniques are applied to several cases like the secular drift of the Newton gravitational constant, neutrino magnetic moments, axions and weakly interacting massive particles (WIMPS).

During the Zwicky Transient Facility (ZTF) Phase-I operation, 78 hydrogen-poor superluminous supernovae (SLSNe-I) were discovered in less than three years, making up the largest sample from a single survey. This paper (Paper I) presents the data, including the optical/ultraviolet light curves and classification spectra, while Paper II in this series will focus on the detailed analysis of the light curves and modeling. Our photometry is primarily taken by the ZTF in the $g,r,i$ bands, and with additional data from other ground-based facilities and $\it Swift$. The events of our sample cover a redshift range of $z = 0.06 - 0.67$, with a median and $1\sigma$ error ($16\%$ and $84\%$ percentiles) $z_{med} = 0.265^{+0.143}_{-0.135}$. The peak luminosity covers $-22.9\,{\rm mag} \leq M_{g,peak} \leq -19.9\,$mag, with a median value of $-21.54^{+1.12}_{-0.61}\,$mag. Their light curves evolve slowly with the mean rest-frame rise time of $t_{rise} =42.0\pm17.8\,$days. The luminosity and time scale distributions suggest that low luminosity SLSNe-I with peak luminosity $\sim -20\,$mag or extremely fast rising events ($<10 - 15\,$days) exist but are rare. We confirm previous findings that slowly rising SLSNe-I also tend to fade slowly. The rest-frame color and temperature evolution show large scatters, suggesting that the SLSN-I population may have diverse spectral energy distributions. The peak rest-frame color shows a moderate correlation with the peak absolute magnitude, $\it i.e.$ brighter SLSNe-I tend to have bluer colors. With optical and ultraviolet photometry, we construct bolometric luminosity and derive a bolometric correction relation generally applicable for converting $g,r$-band photometry to bolometric luminosity for SLSNe-I.

We present analysis of the light curves (LCs) of 77 hydrogen-poor superluminous supernovae (SLSNe-I) discovered during the Zwicky Transient Facility Phase-I operation. We find that the majority ($67\%$) of the sample can be fit equally well by both magnetar and ejecta-circumstellar medium (CSM) interaction plus $^{56}Ni$ decay models. This implies that LCs alone can not unambiguously constrain the physical power sources for SLSNe-I. However, $20\%$ of the sample show clear signatures such as inverted V-shape or steep declining LCs, which are better described by the CSM+Ni model. The remaining $13\%$ of the sample favor the magnetar model. Moreover, our analysis shows that LC undulations are quite common, observed in $34-62\%$ of the sample, depending on the strength of the undulations and the quality of the LCs. The majority ($73\%$) of the undulations occur post-peak and "bumps"/"dips" each account for around half of the undulations. Undulations show a wide range in energy and duration, with median values and 1$\sigma$ errors of $1.8\%^{+3.4\%}_{-0.9\%}\,\rm E_{rad,total}$ and $26.2^{+22.6}_{-10.7}\,$days, respectively. Our analysis of the undulation time scales suggests that intrinsic temporal variations of the central engine can explain half of the undulating events, while CSM interaction can account for the majority of the sample. Finally, all of the well-observed He-rich SLSNe-Ib have either strongly undulating LCs or the LCs are much better fit by the CSM+Ni model. These observations imply that their progenitor stars have not had enough time to lose all of the He-envelopes before supernova explosions, and H-poor CSM are likely to present in these events.

We revisit the model of axion inflation in the context of stochastic inflation and investigate the effects of the stochastic noises associated to the electromagnetic fields. Because of the parity violating interaction, one polarization of the gauge field is amplified inducing large curvature perturbation power spectrum. Taking into account the stochastic kicks arising from the short modes at the time of horizon crossing we obtain the corresponding Langevin equations for the long modes of the electromagnetic and axion fields. It is shown that a mean-reverting process governs the dynamics of the electromagnetic fields such that the tachyonic growth of the gauge fields is balanced by the diffusion forces. As the instability parameter grows towards the end of inflation, the large curvature perturbations induced from gauge field perturbations lead to copious production of small mass primordial black holes (PBHs). It is shown that the produced PBHs follow a Gaussian statistics. Imposing the observational constraints on PBHs formation relaxes the previous bounds on the instability parameter by about fifty percents.

The chromosphere is the active atmosphere in which energetic eruption events, such as flares, occur. Chromospheric activity is driven by the magnetic field generated by stellar rotation and convection. The relationship between chromospheric activity and the Rossby number, the ratio of the rotational period to the convective turnover time, has been extensively examined for many types of stars, by using narrow chromospheric emission lines, such as the Ca II lines and the Mg II h and k lines. However, the stars with small Rossby numbers, i.e., stars with rapid rotations and/or long convective turnover times, show constant strengths of such lines against the Rossby number. In this study, we investigate the infrared Mg I emission lines at 8807 A of 47 zero-age main-sequence (ZAMS) stars in IC 2391 and IC 2602 using the archive data of the Anglo-Australian Telescope at the University College London Echelle Spectrograph. After subtracting the photospheric absorption component, the Mg I line is detected as an emission line for 45 ZAMS stars, whose equivalent widths are between 0.02 A and 0.52 A. A total of 42 ZAMS stars show the narrower Mg I emission lines instead of the Ca II infrared triplet emission lines, suggesting that they are formed at different depths. The ZAMS stars with smaller Rossby numbers show stronger Mg I emission lines. The Mg I emission line is not saturated even in "the saturated regime of the Ca II emission lines," i.e., Rossby number < 10^(-1.1). The Mg I emission line is considered to be a good indicator of chromospheric activity, particularly for active objects.

We perform particle-in-cell simulations to elucidate the microphysics of relativistic weakly magnetized shocks loaded with electron-positron pairs. Various external magnetizations $\sigma\lesssim 10^{-4}$ and pair-loading factors $Z_\pm \lesssim 10$ are studied, where $Z_\pm$ is the number of loaded electrons and positrons per ion. We find the following. (1) The shock becomes mediated by the ion Larmor gyration in the mean field when $\sigma$ exceeds a critical value $\sigma_{\rm L}$ that decreases with $Z_\pm$. At $\sigma\lesssim\sigma_{\rm L}$ the shock is mediated by particle scattering in the self-generated microturbulent fields, the strength and scale of which decrease with $Z_\pm$, leading to lower $\sigma_{\rm L}$. (2) The energy fraction carried by the post-shock pairs is robustly in the range between 20% and 50% of the upstream ion energy. The mean energy per post-shock electron scales as $\overline{E}_{\rm e}\propto (Z_\pm+1)^{-1}$. (3) Pair loading suppresses nonthermal ion acceleration at magnetizations as low as $\sigma\approx 5\times 10^{-6}$. The ions then become essentially thermal with mean energy $\overline{E}_{\rm i}$, while electrons form a nonthermal tail, extending from $E\sim (Z_\pm + 1)^{-1}\overline{E}_{\rm i}$ to $\overline{E}_{\rm i}$. When $\sigma = 0$, particle acceleration is enhanced by the formation of intense magnetic cavities that populate the precursor during the late stages of shock evolution. Here, the maximum energy of the nonthermal ions and electrons keeps growing over the duration of the simulation. Alongside the simulations, we develop theoretical estimates consistent with the numerical results. Our findings have important implications for models of early gamma-ray burst afterglows.

Properties of the first generation of stars (Pop III), such as their initial mass function (IMF), are poorly constrained by observations and have yet to converge between simulations. The cosmological 21-cm signal of neutral hydrogen is predicted to be sensitive to Lyman band photons produced by these stars, thus providing a unique way to probe the first stellar population. In this paper, we investigate the impacts of the Pop III IMF on the cosmic dawn 21-cm signal via the Wouthysen-Field effect, Lyman-Werner feedback, Ly-alpha heating, and CMB heating. We calculate the emission spectra of star-forming halos for different IMFs by integrating over individual metal-free stellar spectra, computed from a set of stellar evolution histories and stellar atmospheres, and taking into account variability of the spectra with stellar age. Through this study, we therefore relax two common assumptions: that the zero-age main sequence emission rate of a Pop III star is representative of its lifetime mean emission rate, and that Pop III emission can be treated as instantaneous. Exploring a bottom-heavy, a top-heavy, and intermediate IMFs, we show that variations in the 21-cm signal are driven by stars lighter than 20 solar masses. For the explored models we find maximum relative differences of 68% in the cosmic dawn global 21-cm signal, and 137% between power spectra. Although this impact is modest, precise modelling of the first stars and their evolution is necessary for accurate prediction and interpretation of the 21-cm signal.

Full-polarization primary beam patterns of MeerKAT antennas have been measured in L-band (856 to 1711 MHz) by means of radio holography using celestial targets. This paper presents the observed frequency dependent properties of these beams, and guides users of this 64 antenna radio telescope that are concerned by its direction dependent polarization effects. In this work the effects on the primary beams due to modeling simplifications, bandwidth averaging, gravitational loading and ambient temperature are quantified within the half power region of the beam. A perspective is provided on the level of significance of typical use case effects. It is shown that antenna pointing is a leading cause of inaccuracy for telescope users in the presumed beam shape, introducing errors exceeding 1% in power near the half power point of beams, owing to a telescope pointing accuracy of $\sigma\approx 0.6$ arcminutes. Disregarding these pointing errors, variability in the Stokes I beam shape relative to the array average is most commonly around 0.3% in power; however, the impact above 1500 MHz is on average triple that of the lower half of the band. This happens because the proportion of higher order waveguide modes that are activated and propagate is sensitive to small manufacturing differences in the orthomode transducer for each receiver. Primary beam correction verification test results for an off-axis spectral index measurement experiment are included.

Context. There is a class of binary post-asymptotic giant branch (post-AGB) stars that exhibit remarkable near-infrared (NIR) excess. Such stars are surrounded by Keplerian or quasi-Keplerian disks, as well as extended outflows composed of gas escaping from the disk. This class can be subdivided into disk- and outflow-dominated sources, depending on whether it is the disk or the outflow that represents most of the nebular mass, respectively. The chemistry of this type of source has been practically unknown thus far. Methods. We focused our observations on the 1.3, 2, 3 mm bands of the 30 m IRAM telescope and on the 7 and 13 mm bands of the 40 m Yebes telescope. Our observations add up around 600 hours of telescope time. Results. We present the first single-dish molecular survey of mm-wave lines in nebulae around binary post-AGB stars. We conclude that the molecular content is relatively low in nebulae around binary post-AGB stars, as their molecular lines and abundances are especially weaker compared with AGB stars. This fact is very significant in those sources where the Keplerian disk is the dominant component of the nebula. The study of their chemistry allows us to classify nebulae around AC Her, the Red Rectangle, AI CMi, R Sct, and IRAS 20056+1834 as O-rich, while that of 89 Her is probably C-rich. The calculated abundances of the detected species other than CO are particularly low compared with AGB stars. The initial stellar mass derived from the 17O/18O ratio for the Red Rectangle and 89 Her is compatible with the central total stellar mass derived from previous mm-wave interferometric maps. The very low 12CO/13CO ratios found in binary post-AGB stars reveal a high 13CO abundance compared to AGB and other post-AGB stars.

We announce the detection of two new planetary-mass companions around Kepler-451 binary system in addition to the one detected previously based on eclipse timing variation analysis. We found that an inner planet with 43 d period with a minimum mass of 1.76 Mjup and an outer one with a $\sim$ 1800 d orbital period with a minimum mass of 1.61 Mjup can explain the periodic variations in the residuals of the one-planet fit of the eclipse timings. We updated the orbital period of the middle planet as 406 d, and determined its eccentricity as 0.33. The newly discovered outer planet is also on an eccentric orbit (0.29), while the innermost planet was assumed to have a circular orbit. All three Jovian planets have similar masses, and our dynamical stability test yields that the system is stable.

Stellar streams are a promising tool to study the Milky Way's dark matter subhalo population, as interactions with subhalos could produce substructure in streams. However, other possible causes for substructure first need to be well understood. Here we study the kinematics and the unusual morphology of the stellar stream Jhelum. Using a combination of ground-based photometry and Gaia EDR3 astrometry we characterize the morphology of Jhelum. We combine this new data with radial velocities from the literature to perform orbit integrations of the stream in static Galactic potentials. We also explore N-body models in the presence of large perturbers to explain some of the kinematic and morphological features observed. The new data reveals a previously unreported tertiary component in the stream, as well as several gaps and a kink-like feature in its narrow component. We find that for a range of realistic Galactic potentials, no single orbit is able to reproduce Jhelum's radial velocity data entirely. A generic property of the orbital solutions is that they share a similar orbital plane to Sagittarius and this leads to repeated encounters with the stream. Using N-body simulations that include a massive Sagittarius, we show that these encounters are able to reproduce the narrow and broad components in Jhelum, as well as create a tertiary component in some cases. We also find evidence that such encounters can result in an apparent increase in the velocity dispersion of the stream by a factor up to ~ 5 due to overlapping narrow and broad components. Our findings suggest that the Jhelum stream is even more complex than once thought, however its morphology and kinematics can be relatively easily explained via the interactions with Sagittarius. In this scenario, the formation of Jhelum's narrow and broad components occurs naturally, yet some of the smaller gap-like features remain to be explained.

A solar-type system starts from an initial molecular core that acquires organic complexity as it evolves. The so-called prestellar cores that can be studied are rare, which has hampered our understanding of how organic chemistry sets in and grows. Aims. We selected the best prestellar core targets from the cold core catalogue that represent a diversity in terms of their environment to explore their chemical complexity: 1390 (in the compressed shell of Lambda Ori), 869 (in the MBM12 cloud), and 4149 (in the California nebula). We obtained a spectral survey with the IRAM 30 m telescope in order to explore the molecular complexity of the cores. We carried out a radiative transfer analysis of the detected transitions in order to place some constraints on the physical conditions of the cores and on the molecular column densities. We also used the molecular ions in the survey to estimate the cosmic-ray ionisation rate and the S/H initial elemental abundance using a gas-phase chemical model to reproduce their abundances. We found large differences in the molecular complexity (deuteration, complex organic molecules, sulphur, carbon chains, and ions) and compared their chemical properties with a cold core and two prestellar cores. The chemical diversity we found in the three cores seems to be correlated with their chemical evolution: two of them are prestellar (1390 and 4149), and one is in an earlier stage (869). The influence of the environment is likely limited because cold cores are strongly shielded from their surroundings. The high extinction prevents interstellar UV radiation from penetrating deeply into the cores. Higher spatial resolution observations of the cores are therefore needed to constrain the physical structure of the cores, as well as a larger-scale distribution of molecular ions to understand the influence of the environment on their molecular complexity.

In the context of extreme adaptive optics (ExAO) for large telescopes, we present the Kraken multi-frame blind deconvolution (MFBD) algorithm for processing high-cadence acquisitions, capable to provide a diffraction-limited estimation of the source brightness distribution. This is achieved by a data modeling of each frame in the sequence driven by the estimation of the instantaneous wavefront at the entrance pupil. Under suitable physical contraints, numerical convergence is guaranteed by an iteration scheme starting from a Compact MFBD (CMFBD) which provides a very robust initial guess which only employs a few frames. We describe the mathematics behind the process and report the high-resolution reconstruction of the spectroscopic binary {\alpha} And (16.3 mas separation) acquired with the precursor of SHARK-VIS, the upcoming high-contrast camera in the visible for the Large Binocular Telescope.

Black hole neutron star (BHNS) mergers have recently been detected through their gravitational-wave (GW) emission. BHNS mergers could also produce electromagnetic (EM) emission as a short gamma-ray burst (sGRB), and/or an sGRB afterglow upon interaction with the circummerger medium. Here, we make predictions for the expected detection rates with the Square Kilometre Array Phase 1 (SKA1) of sGRB radio afterglows associated with BHNS mergers. We also investigate the benefits of a multimessenger analysis in inferring the properties of the merging binary. We simulate a population of BHNS mergers and estimate their sGRB afterglow flux to obtain the detection rates with SKA1. We investigate how this rate depends on the GW detector sensitivity, the primary black hole (BH) spin, and the neutron star equation of state. We then perform a multimessenger Bayesian inference study on a fiducial BHNS merger. We simulate its sGRB afterglow and GW emission and take systematic errors into account. The expected rates of a combined GW and radio detection with the current generation GW detectors are likely low. Due to the much increased sensitivity of future GW detectors like the Einstein Telescope, the chances of an sGRB localisation and radio detection increase substantially. The unknown distribution of the BH spin has a big influence on the detection rates, however, and it is a large source of uncertainty. Furthermore, for our fiducial BHNS merger we are able to infer both the binary source parameters as well as the parameters of the sGRB afterglow simultaneously when combining the GW and radio data. The radio data provides useful extra information on the binary parameters such as the mass ratio but this is limited by the systematic errors involved. A better understanding of the systematics will further increase the amount of information on the binary parameters that can be extracted from this radio data.

Future ground-based telescopes, such as the 4-metre class facilities DKIST and EST, will dramatically improve on current capabilities for simultaneous multi-line polarimetric observations in a wide range of wavelength bands, from the near-ultraviolet to the near-infrared. As a result, there will be an increasing demand for fast diagnostic tools, i.e., inversion codes, that can infer the physical properties of the solar atmosphere from the vast amount of data these observatories will produce. The advent of substantially larger apertures, with the concomitant increase in polarimetric sensitivity, will drive an increased interest in observing chromospheric spectral lines. Accordingly, pertinent inversion codes will need to take account of line formation under general non-local thermodynamic equilibrium (NLTE) conditions. Several currently available codes can already accomplish this, but they have a common practical limitation that impairs the speed at which they can invert polarised spectra, namely that they employ numerical evaluation of the so-called response functions to changes in the atmospheric parameters, which makes them less suitable for the analysis of very large data volumes. Here we present DeSIRe (Departure coefficient aided Stokes Inversion based on Response functions), an inversion code that integrates the well-known inversion code SIR with the NLTE radiative transfer solver RH. The DeSIRe runtime benefits from employing analytical response functions computed in local thermodynamic equilibrium (through SIR), modified with fixed departure coefficients to incorporate NLTE effects in chromospheric spectral lines. This publication describes the operating fundamentals of DeSIRe and describes its behaviour, robustness, stability, and speed. The code is ready to be used by the solar community and is being made publicly available.

Context. Understanding the conditions in which stars and stellar clusters form is of great importance. In particular the role that stellar feedback may have is still hampered by large uncertainties. Aims. We investigate the role played by ionising radiation and protostellar outflows during the formation and evolution of a stellar cluster. To self-consistently take into account gas accretion, we start with clumps of tens of parsecs in size. Methods. Using an adaptive mesh refinement code, we run magneto-hydrodynamical numerical simulations aiming at describing the collapse of massive clumps with either no stellar feedback or taking into account ionising radiation and/or protostellar jets. Results. Stellar feedback substantially modifies the protostellar cluster properties, in several ways. We confirm that protostellar outflows reduce the star formation rate by a factor of a few, although the outflows do not stop accretion and likely enough do not modify the final cluster mass. On the other hand, ionising radiation, once sufficiently massive stars have formed, efficiently expels the remaining gas and reduces the final cluster mass by a factor of several. We found that while HII radiation and jets barely change the distribution of high density gas, the latter increases, at a few places, the dense gas velocity dispersion again by a factor of several. As we are starting from a relatively large scale, we found that the clusters whose mass and size are respectively on the order of a few 1000 M and a fraction of parsec, present a significant level of rotation. Moreover we found that the sink particles which mimic the stars themselves, tend to have rotation axis aligned with the cluster large scale rotation. Finally, computing the classical Q parameter used to quantify stellar cluster structure, we infer that when jets are included in the calculation, [...]

The thermal Sunyaev-Zel'dovich (tSZ) effect is the distortion generated in the cosmic microwave background (CMB) spectrum by the inverse-Compton scattering of CMB photons off free, energetic electrons, primarily located in the intracluster medium (ICM). Cosmic infrared background (CIB) photons from thermal dust emission in star-forming galaxies are expected to undergo the same process. In this work, we perform the first calculation of the resulting tSZ-like distortion in the CIB. Focusing on the CIB monopole, we use a halo model approach to calculate both the CIB signal and the Compton-$y$ field that generates the distortion. We self-consistently account for the redshift co-evolution of the CIB and Compton-$y$ fields: they are (partially) sourced by the same dark matter halos, which introduces new aspects to the calculation as compared to the CMB case. We find that the inverse-Compton distortion to the CIB monopole spectrum has a positive (negative) peak amplitude of $\approx 4$ Jy/sr ($\approx -5$ Jy/sr) at 2250 GHz (940 GHz). In contrast to the usual tSZ effect, the distortion to the CIB spectrum has two null frequencies, at approximately 196 GHz and 1490 GHz. We perform a Fisher matrix calculation to forecast the detectability of this new distortion signal by future experiments. $\textit{PIXIE}$ would have sufficient instrumental sensitivity to detect the signal at $4\sigma$, but foreground contamination reduces the projected signal-to-noise by a factor of $\approx 40$. A future ESA Voyage 2050 spectrometer would detect the CIB distortion at $\approx 2$-$10\sigma$ significance, even after marginalizing over foregrounds. A measurement of this signal would provide new information on the star formation history of the Universe, and the distortion anisotropies may be accessible by near-future ground-based experiments.

We present stellar population models to calculate the mass-to-light ratio ($\Upsilon_*$) based on galaxy's colors ranging from $GALEX$ FUV to Spitzer IRAC1 at 3.6$\mu$m. We present a new composite bulge+disk $\Upsilon_*$ model that considers the varying contribution from bulges and disks based on their optical and near-IR colors. Using these colors, we build plausible star formation histories and chemical enrichment scenarios based on the star formation rate-stellar mass and mass-metallicity correlations for star-forming galaxies. The most accurate prescription is to use the actual colors for the bulge and disk components to constrain $\Upsilon_*$; however, a reasonable bulge+disk model plus total color only introduces 5% more uncertainty. Full bulge+disk $\Upsilon_*$ prescriptions applied to the baryonic TF relation improves the linearity of the correlation, increases the slope and reduces the total scatter by 4%.

While stars are often found in binary systems, brown dwarf binaries are much rarer. Brown dwarf--brown dwarf pairs are typically difficult to resolve because they often have very small separations. Using brown dwarfs discovered with data from the Wide-field Infrared Survey Explorer (WISE) via the Backyard Worlds: Planet 9 citizen science project, we inspected other, higher resolution, sky surveys for overlooked cold companions. During this process we discovered the brown dwarf binary system CWISE J0146$-$0508AB, which we find has a very small chance alignment probability based on the similar proper motions of the components of the system. Using follow-up near-infrared spectroscopy with Keck/NIRES, we determined component spectral types of L4 and L8 (blue), making CWISE J0146$-$0508AB one of only a few benchmark systems with a blue L dwarf. At an estimated distance of $\sim$40 pc, CWISE J0146$-$0508AB has a projected separation of $\sim$129 AU, making it the widest separation brown dwarf pair found to date. We find that such a wide separation for a brown dwarf binary may imply formation in a low-density star-forming region.

Complexity Theory is highly interdisciplinary, therefore any regularities must hold on all levels of organization, independent on the nature of the system. An open question in science is how complex systems self-organize to produce emergent structures and properties, a branch of non-equilibrium thermodynamics. It has long been known that there is a quantity-quality transition in natural systems. This is to say that the properties of a system depend on its size. More recently, this has been termed the size-complexity rule, which means that to increase their size, systems must increase their complexity, and that to increase their complexity they must grow in size. This rule goes under different names in different disciplines and systems of different nature, such as the area-speciation rule, economies of scale, scaling relations (allometric) in biology and for cities, and many others. We apply the size-complexity rule to stars to compare them with other complex systems in order to find universal patterns of self-organization independent of the substrate. Here, as a measure of complexity of a star, we are using the degree of grouping of nucleons into atoms, which reduces nucleon entropy, increases the variety of elements, and changes the structure of the star. As seen in our previous work, complexity, using action efficiency, is in power law proportionality of all other characteristics of a complex system, including its size. Here we find that, as for the other systems studied, the complexity of stars is in a power law proportionality with their size - the bigger a system is, the higher its level of complexity is - despite differing explosion energies and initial metallicities from simulations and data, which confirms the size-complexity rule and our model.

Complex scalar fields charged under approximate $U(1)$ symmetries appear in well-motivated extensions of the Standard Model. One example is the field that contains the QCD axion field associated with the Peccei-Quinn symmetry; others include flat directions in supersymmetric theories with baryon, lepton, or flavor charges. These fields may take on large values and rotate in field space in the early universe. The relevant approximate $U(1)$ symmetry ensures that the angular direction of the complex field is light during inflation and that the rotation is thermodynamically stable and is long-lived. These properties allow rotating complex scalar fields to naturally serve as curvatons and explain the observed perturbations of the universe. The scenario imprints non-Gaussianity in the curvature perturbations, likely at a level detectable in future large scale structure observations. The rotation can also explain the baryon asymmetry of the universe without producing excessive isocurvature perturbations.

A cosmological model in an Einstein-Cartan framework endowed with torsion is studied. For a torsion function assumed to be proportional to Hubble expansion function, namely $\phi=-\alpha H$, the contribution of torsion function as a dark matter component is studied in two different approaches. In the first one, the total matter energy density is altered by torsion coupling $\alpha$, giving rise to an effective dark matter and cosmological constant terms that reproduce quite well the flat cosmic concordance model. In the second approach, starting with just standard baryonic matter plus a cosmological constant term, it is obtained that the coupling of torsion with baryons and cosmological constant term naturally gives rise to a dark matter contribution, together a modified cosmological term. In this model the dark matter sector can be interpreted as an effective coupling of the torsion function with the ordinary baryonic matter and cosmological constant. Finally, it is shown that both models are totally compatible with recent cosmological data from Supernovae and Hubble parameter measurements.

We examine statistics of magnetic field vector components to explore how intermittency evolves from near sun plasma to radial distances as large as 10 au. Statistics entering the analysis include auto-correlation, magnetic structure functions of order n (SFn), and scale dependent kurtosis (SDK), each grouped in ranges of heliocentric distance. The Goddard Space Flight Center Space Physics Data Facility (SPDF) provides magnetic field measurements for resolutions of 6.8ms for Parker Solar Probe, 6s for Helios, and 1.92s for Voyager 1. We compute SF2 to determine the scales encompassing the inertial range and examine SDK to investigate degree of non-Gaussianity. Auto-correlations are used to resolve correlation scales. Correlation lengths and ion inertial lengths provide an estimate of effective Reynolds number (Re). Variation in Re allows us to examine for the first time the relationship between SDK and Re in an interplanetary plasma. A conclusion from this observed relationship is that regions with lower Re at a fixed physical scale have on average lower kurtosis, implying less intermittent behavior. Kolmogorov refined similarity hypothesis is applied to magnetic SFn and kurtosis to calculate intermittency parameters and fractal scaling in the inertial range. A refined Voyager 1 magnetic field dataset is generated.

We present a method for measurements of electric dipole moments on (sub)-mm size (basalt) particles levitated in an acoustic trap and centered within a plate capacitor. If an electric field is applied the particles oscillate with specific frequencies due to their permanent dipole moments. We observe dipole moments on the order of $D_P = 10^{-15} ... 10^{-14} \rm \, C \, m $. The dipole moment increases in small aggregates with the number of grains and is larger for samples vibrated (tribocharged) before trapping. The basalt grains show no sign of change in their dipole moment during measurements, implying a timescale for charge mobility being at least larger than minutes.

Various profiles of matter distribution in galactic halos (such as Navarro-Frenk-White, Burkert, Hernquist, Moore, Taylor-Silk and others) are considered here as sources for the Einstein equations. We solve these equations and find exact solutions which represent the metric of a central black hole immersed in a galactic halo. Even though in the general case the solution is numerical, very accurate general analytical metric, which includes all the particular models, are found in the astrophysically relevant regime, when the mass of the galaxy is much smaller than the characteristic scale in the halo.