Papers for Monday, Aug 30 2021

We present Gemini/NIFS near-IR integral field spectroscopy of the fields-of-view around two AGNs behind the Fermi Bubbles (PDS 456 and 1H1613-097) to search for molecular gas in the Milky Way's nuclear wind. These two AGN sightlines were selected by the presence of high-velocity neutral and ionized gas seen in UV absorption. We do not detect any extended emission from the H2 ro-vibrational S(0) and S(1) lines at 2.224 and 2.122 microns in either direction. For the S(1) line, the 3-sigma surface brightness limits derived from spectra extracted across the full 3x3 arcsecond NIFS field-of-view are 2.4e-17 erg/cm2/s/A/arcsec2 for PDS 456 and and 4.9e-18 erg/cm2/s/A/arcsec2 for 1H1613-097. Given these non-detections, we conclude that CO emission-line studies and H2 UV absorption-line studies are more promising approaches for characterizing the molecular gas in the Fermi Bubbles.

We present far- and near-ultraviolet absorption spectroscopy of the $\sim$23 Myr edge-on debris disk surrounding the A0V star $\eta$ Telescopii, obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph. We detect absorption lines from C I, C II, O I, Mg II, Al II, Si II, S II, Mn II, Fe II, and marginally N I. The lines show two clear absorption components at $-22.7\pm0.5$ km s$^{-1}$ and $-17.8\pm0.7$ km s$^{-1}$, which we attribute to circumstellar (CS) and interstellar (IS) gas, respectively. CO absorption is not detected, and we find no evidence for star-grazing exocomets. The CS absorption components are blueshifted by $-16.9\pm2.6$ km s$^{-1}$ in the star's reference frame, indicating that they are outflowing in a radiatively driven disk wind. We find that the C/Fe ratio in the $\eta$ Tel CS gas is significantly higher than the solar ratio, as is the case in the $\beta$ Pic and 49 Cet debris disks. Unlike those disks, however, the measured C/O ratio in the $\eta$ Tel CS gas is consistent with the solar value. Our analysis shows that because $\eta$ Tel is an earlier type star than $\beta$ Pic and 49 Cet, with more substantial radiation pressure at the dominant C II transitions, this species cannot bind the CS gas disk to the star as it does for $\beta$ Pic and 49 Cet, resulting in the disk wind.

A self-interacting dark matter halo can experience gravothermal collapse, resulting in a central core with an ultrahigh density. It can further contract and collapse into a black hole, a mechanism proposed to explain the origin of supermassive black holes. We study dynamical instability of the core in general relativity. We use a truncated Maxwell-Boltzmann distribution to model the dark matter distribution and solve the Tolman-Oppenheimer-Volkoff equation. For given model parameters, we obtain a series of equilibrium configurations and examine their dynamical instability based on considerations of total energy, binding energy, fractional binding energy, and adiabatic index. The numerical results from our semi-analytical method are in good agreement with those from fully relativistic N-body simulations. We further show for the instability to occur in the classical regime, the boundary temperature of the core should be at least $10\%$ of the mass of dark matter particles; for a $10^9~{\rm M_\odot}$ seed black hole, the particle mass needs to be larger than a few keV. These results can be used to constrain different collapse models, in particular, those with dissipative dark matter interactions.

We report the discovery of SDSS J133725.26+395237.7 (hereafter SDSS J1337+3952), a double-lined white dwarf (WD+WD) binary identified in early data from the fifth generation Sloan Digital Sky Survey (SDSS-V). The double-lined nature of the system enables us to fully determine its orbital and stellar parameters with follow-up Gemini spectroscopy and Swift UVOT ultraviolet fluxes. The system is nearby ($d = 113$ pc), and consists of a $0.51\, M_\odot$ primary and a $0.32\, M_\odot$ secondary. SDSS J1337+3952 is a powerful source of gravitational waves in the millihertz regime, and will be detectable by future space-based interferometers. Due to this gravitational wave emission, the binary orbit will shrink down to the point of interaction in $\approx 220$ Myr. The inferred stellar masses indicate that SDSS J1337+3952 will likely not explode as a Type Ia supernova (SN Ia). Instead, the system will probably merge and evolve into a rapidly rotating helium star, and could produce an under-luminous thermonuclear supernova along the way. The continuing search for similar systems in SDSS-V will grow the statistical sample of double-degenerate binaries across parameter space, constraining models of binary evolution and SNe Ia.

We select eight nearby AGNs which, based on previous work, appear to be Compton-thin in the line of sight. We model with MYTORUS their broadband X-ray spectra from 20 individual observations with $Suzaku$, accounting self-consistently for Fe K$\alpha$ line emission, as well as direct and scattered continuum from matter with finite column density and solar Fe abundance. Our model configuration allows us to measure the global, out of the line of sight, equivalent hydrogen column density separately from that in the line of sight. For 5 out of 20 observations (in 3 AGNs) we find that the global column density is in fact $\gtrsim 1.5 \times 10^{24}$cm$^{-2}$, consistent with the distant scattering matter being Compton-thick. For a fourth AGN, 2 out of 5 observations are also consistent with being Compton-thick, although with large errors. Some of these AGNs have been reported to host relativistically broadened Fe K$\alpha$ emission. Based on our modeling, the Fe K$\alpha$ emission line is not resolved in all but two $Suzaku$ observations, and the data can be fitted well with models that only include a narrow Fe K$\alpha$ emission line.

Accreting black holes are sources of major interest in astronomy, particular those launching jets because of their ability to accelerate particles, and dramatically affect their surrounding environment up to very large distances. The spatial, energy and time scales at which a central active black hole radiates and impacts its environment depend on its mass. The implied scale-invariance of accretion/ejection physics between black hole systems of different central masses has been confirmed by several studies. Therefore, designing a self-consistent theoretical model that can describe such systems, regardless of their mass, is of crucial importance to tackle a variety of astrophysical sources. We present here a new and significantly improved version of a scale invariant, steady-state, multi-zone jet model, which we rename bhjet, resulting from the efforts of our group to advance the modelling of black hole systems. We summarise the model assumptions and basic equations, how they have evolved over time, and the additional features that we have recently introduced. These include additional input electron populations, the extension to cyclotron emission in near-relativistic regime, an improved multiple inverse Compton scattering method, external photon seeds typical of AGN and a magnetically-dominated jet dynamical model as opposed to the pressure-driven jet configuration present in older versions. In this paper, we publicly release the code on Github and, in order to facilitate the user's approach to its many possibilities, showcase a few applications as a tutorial.

Stellar members of binary systems are formed from the same material, therefore they should be chemically identical. However, recent high-precision studies have unveiled chemical differences between the two members of binary pairs composed by Sun-like stars. The very existence of these chemically inhomogeneous binaries represents one of the most contradictory examples in stellar astrophysics and source of tension between theory and observations. It is still unclear whether the abundance variations are the result of chemical inhomogeneities in the protostellar gas clouds or instead if they are due to planet engulfment events occurred after the stellar formation. While the former scenario would undermine the belief that the chemical makeup of a star provides the fossil information of the environment where it formed, a key assumption made by several studies of our Galaxy, the second scenario would shed light on the possible evolutionary paths of planetary systems. Here, we perform a statistical study on 107 binary systems composed by Sun-like stars to provide - for the first time - unambiguous evidence in favour of the planet engulfment scenario. We also establish that planet engulfment events occur in stars similar to our own Sun with a probability ranging between 20 and 35$\%$. This implies that a significant fraction of planetary systems undergo very dynamical evolutionary paths that can critically modify their architectures, unlike our Solar System which has preserved its planets on nearly circular orbits. This study also opens to the possibility of using chemical abundances of stars to identify which ones are the most likely to host analogues of the calm Solar System.

We present the analysis of deep X-ray observations of 10 massive galaxy clusters at redshifts $1.05 < z < 1.71$, with the primary goal of measuring the metallicity of the intracluster medium (ICM) at intermediate radii, to better constrain models of the metal enrichment of the intergalactic medium. The targets were selected from X-ray and Sunyaev-Zel'dovich (SZ) effect surveys, and observed with both the \textit{XMM-Newton} and \textit{Chandra} satellites. For each cluster, a precise gas mass profile was extracted, from which the value of $r_{500}$ could be estimated. This allows us to define consistent radial ranges over which the metallicity measurements can be compared. In general, the data are of sufficient quality to extract meaningful metallicity measurements in two radial bins, $r<0.3r_{500}$ and $0.3<r/r_{500}<1.0$. For the outer bin, the combined measurement for all ten clusters, $Z/Z_{\odot} = 0.21 \pm 0.09$, represents a substantial improvement in precision over previous results. This measurement is consistent with, but slightly lower than, the average metallicity of 0.315 Solar measured at intermediate-to-large radii in low-redshift clusters. Combining our new high-redshift data with the previous low-redshift results allows us to place the tightest constraints to date on models of the evolution of cluster metallicity at intermediate radii. Adopting a power law model of the form $Z \propto \left(1+z\right)^\gamma$, we measure a slope $\gamma = -0.5^{+0.4}_{-0.3}$, consistent with the majority of the enrichment of the ICM having occurred at very early times and before massive clusters formed, but leaving open the possibility that some additional enrichment in these regions may have occurred since a redshift of 2.

Spectroscopic studies of planets outside of our own solar system provide some of the most crucial information about their formation, evolution, and atmospheric properties. In ground-based spectroscopy, the process of extracting the planet's signal from the stellar and telluric signal has proven to be the most difficult barrier to accurate atmospheric information. However, with novel normalization and smoothing methods, this barrier can be minimized and the detection significance dramatically increased over existing methods. In this paper, we take two examples of CRIRES emission spectroscopy taken of HD 209458 b and HD 179949 b and apply SPORK (SPectral cOntinuum Refinement for telluriKs) and iterative smoothing to boost the detection significance from 5.78 to 9.71 sigma and from 4.19 sigma to 5.90 sigma, respectively. These methods, which largely address systematic quirks introduced by imperfect detectors or reduction pipelines, can be employed in a wide variety of scenarios, from archival data sets to simulations of future spectrographs.

We present the second part of results of the on-going project of searching for and studying eXtremely Metal-Poor (XMP, adopted as those with Z(gas) <~ Zo/30, or with 12+log(O/H) <~ 7.21~dex) very gas-rich blue dwarfs in voids.They were first identified in course of the 'unbiased' study of galaxy population in the nearby Lynx-Cancer void. These very rare and unusual galaxies seem to be the best proxies of so-called Very Young Galaxies (VYGs) defined recently in model simulations by Tweed et al. To date, for 16 preselected void XMP candidates, we obtained with the SAO 6-m telescope (BTA) spectra suitable for determination of O/H. For majority of the observed galaxies, the principal line [OIII]4363 used for the direct classical T_e method of O/H determination, is undetected. Therefore, to estimate O/H, we use a new 'Strong-lines' method by Izotov et al. This appears the most accurate empirical O/H estimator for the range of 12+log(O/H) < 7.4-7.5. For higher O/H objects, we use the semi-empirical method by Izotov and Thuan with our modification accounting for variance of the excitation parameter O32. Six of those 16 candidates are found to be the confident XMP dwarfs. In addition, eight studied galaxies are somewhat less metal-poor, with 12+log(O/H) = 7.24-7.33. They also can fall into the category of VYG candidates. With account of the recently published by us and previously known (9 prototype galaxies) XMP gas-rich void objects, the new findings increase the number of this type galaxies to the total of 19.

Blazars constitute the vast majority of extragalactic $\gamma$-ray sources. They can also contribute a sizable fraction of the diffuse astrophysical neutrinos detected by IceCube. In the past few years, the real-time alert system of IceCube has led to multiwavelength follow-up of very high-energy neutrino events of plausible astrophysical origin. Spatial and temporal coincidences of these neutrino events with the high-activity state of $\gamma$-ray blazars can provide a unique opportunity to decipher cosmic-ray interactions in the relativistic jets. Assuming that blazars accelerate cosmic rays up to ultrahigh energies ($E>10^{17}$ eV), we calculate the "guaranteed" contribution to the line-of-sight cosmogenic $\gamma$-ray and neutrino fluxes from four blazars associated with IceCube neutrino events. Detection of these fluxes by upcoming $\gamma$-ray imaging telescopes like CTA and/or by planned neutrino detectors like IceCube-Gen2 may lead to the first direct signature(s) of ultrahigh-energy cosmic-ray (UHECR) sources. We find that detection of the cosmogenic neutrino fluxes from the blazars TXS~0506+056, PKS~1502+106 and GB6~J1040+0617 would require UHECR luminosity $\gtrsim 10$ times the inferred neutrino luminosity from the associated IceCube events. Blazars TXS~0506+056, 3HSP~J095507.9+355101 and GB6~J1040+0617 can be detected by CTA if the UHECR luminosity is $\gtrsim 10$ times the neutrino luminosity inferred from the associated IceCube events. Given their relatively low redshifts and hence total energetics, TXS~0506+056 and 3HSP~J095507.9+355101 should be the prime targets for upcoming large neutrino and $\gamma$-ray telescopes.

We report on the host association of FRB 20181030A, a repeating fast radio burst (FRB) with a low dispersion measure (DM, 103.5 pc cm$^{-3}$) discovered by CHIME/FRB Collaboration et al. (2019a). Using baseband voltage data saved for its repeat bursts, we localize the FRB to a sky area of 5.3 sq. arcmin (90% confidence). Within the FRB localization region, we identify NGC 3252 as the most promising host, with an estimated chance coincidence probability $< 2.5 \times 10^{-3}$. Moreover, we do not find any other galaxy with M$_{r} < -15$ AB mag within the localization region to the maximum estimated FRB redshift of 0.05. This rules out a dwarf host 5 times less luminous than any FRB host discovered to date. NGC 3252 is a star-forming spiral galaxy, and at a distance of $\approx$ 20 Mpc, it is one of the closest FRB hosts discovered thus far. From our archival radio data search, we estimate a 3$\sigma$ upper limit on the luminosity of a persistent compact radio source (source size $<$ 0.3 kpc at 20 Mpc) at 3 GHz to be ${\rm 2 \times 10^{26} erg~s^{-1} Hz^{-1}}$, at least 1500 times smaller than that of the FRB 20121102A persistent radio source. We also argue that a population of young millisecond magnetars alone cannot explain the observed volumetric rate of repeating FRBs. Finally, FRB 20181030A is a promising source for constraining FRB emission models due to its proximity, and we strongly encourage its multi-wavelength follow-up.

We revisit a possible scale-dependence of local-type primordial non-Gaussianities induced by super-horizon evolution of scalar field perturbations. We develop the formulation based on $\delta N$ formalism and derive the generalized form of the local-type bispectrum and also trispectrum which allows us to implement the scale-dependence and suitably compare model prediction with observational data. We propose simple but phenomenologically meaningful expressions, which encompass the information of a wide range of physically motivated models. We also formulate large-scale power spectrum and bispectrum of biased objects in the presence of the scale-dependent primordial non-Gaussianities. We perform the Fisher analysis for future galaxy surveys and give the projected constraints on the parameters of the generalized local-form of primordial non-Gaussianities.

The column density of free electrons with a cosmological-scale depth, cosmic dispersion measures (DMs), is among the most interesting observables in future transient surveys at radio wavelengths. For future surveys of fast radio bursts (FRBs), we clarify information available from cosmic DMs through cross-correlation analyses of foreground dark matter haloes (hosting galaxies and galaxy clusters) with their known redshifts. With a halo-model approach, we predict that the cross-correlation with cluster-sized haloes is less affected by the details of gastrophysics, providing robust cosmological information. For less massive haloes, the cross-correlation at angular scales of $<10\, \mathrm{arcmin}$ is sensitive to gas expelled from the halo centre due to galactic feedback. Assuming $20000$ FRBs over $20000 \, {\rm deg}^2$ with a localisation error being 3 arcmin, we expect that the cross-correlation signal at halo masses of $10^{12}$-$10^{14}\, M_\odot$ can be measured with a level of $\sim 1\%$ precision in a redshift range of $0<z<1$. Such precise measurements enable to put a $1.5\%$ level constraint on $\sigma_8\, (\Omega_\mathrm{M}/0.3)^{0.5}$ and a $3\%$ level constraint on $(\Omega_\mathrm{b}/0.049)(h/0.67)(f_\mathrm{e}/0.95)$ ($\sigma_8$, $\Omega_\mathrm{M}$, $\Omega_\mathrm{b}$, $h$ and $f_\mathrm{e}$ are the linear mass variance smoothed at $8\, h^{-1}\mathrm{Mpc}$, mean mass density, mean baryon density, the present-day Hubble parameter and fraction of free electrons in cosmic baryons today), whereas the gas-to-halo mass relation in galaxies and clusters can be constrained with a level of $10\%$-$20\%$. Furthermore the cross-correlation analyses can break the degeneracy among $\Omega_\mathrm{b}$, $h$ and $f_\mathrm{e}$, inherent in the DM-redshift relation.

We report optical, ultraviolet, X-ray and $\gamma$-ray observations of BL Lac objects prototype BL Lacertae carried out over a period of nearly 13 years, between 2008 and 2021. The source is characterized by strongly variable emission at all frequencies, often accompanied by spectral changes. In the $\gamma$-ray band several prominent flares have been detected, the largest one reaching the flux of $F_{\rm \gamma}(>196.7\: {\rm MeV})=(4.39\pm1.01)\times10^{-6}\:{\rm photon\:cm^{-2}\:s^{-1}}$, corresponding to the isotropic luminosity of $\simeq10^{47}\:{\rm erg\:s^{-1}}$. At the time of the first major X-ray flare, on MJD 56268.65, a traditional harder-when-brighter trend was observed. During the brightest flare, which occurred on MJD 59128.18, the source instead exhibited a softer-when-brighter trend due to a shift of the synchrotron peak to $10^{16}$ Hz, well into the HBL domain. The widely changing multi-wavelength emission of BL Lacertae was investigated by fitting one-zone and two-zone leptonic models to 520 high-quality and quasi-simultaneous broad-band spectral energy distributions. The HBL behaviour observed during the brightest X-ray flare is interpreted as due to the emergence of synchrotron emission from freshly accelerated particles in a second emission zone.

Despite the close relationship between planetary science and plasma physics, few advanced numerical tools allow to bridge the two topics. The code Menura proposes a breakthrough towards the self-consistent modelling of these overlapping field, in a novel 2-step approach allowing for the global simulation of the interaction between a fully turbulent solar wind and various bodies of the solar system. This article introduces the new code and its 2-step global algorithm, illustrated by a first example: the interaction between a turbulent solar wind and a comet.

The $2p$-$3s$ lines of Fe XVII in the X-ray spectrum of the O-type star $\zeta$ Puppis exhibit an anomalous (3G + M2)/(3F) line ratio of $\sim$1.4, in comparison with $\sim$2.4 for almost all other collisionally excited astrophysical spectra. Based on the work of Mauche et al. (2001), we conjectured that the strong UV field of $\zeta$ Puppis produces the observed ratio by depopulation of metastable $3s$ excited states, and that the ratio can potentially be used as an independent diagnostic of plasma formation radius. We used the Flexible Atomic Code (FAC) collisional-radiative model to model the effect of UV photoexcitation from O stars on the Fe XVII lines. We compared our model calculations to archival spectra of coronal and hot stars from the Chandra HETGS and XMM-Newton RGS to benchmark our calculations for various electron densities and UV field intensities. Our calculations show that UV photoexcitation does not produce a sufficiently large dynamic range in the 3F/(3F + 3G + M2) fraction to explain the difference in the observed ratio between coronal stars and $\zeta$ Pup. Thus, this effect likely cannot explain the observed line ratio of $\zeta$ Pup, and its origin is still unexplained.

The multi-wavelength emission from a newly identified population of `extreme-TeV' blazars, with Compton peak frequencies around 1 TeV, is difficult to interpret with standard one-zone emission models. Large values of the minimum electron Lorentz factor and quite low magnetisation values seem to be required. We propose a scenario where protons and electrons are co-accelerated on internal or recollimation shocks inside the relativistic jet. In this situation, energy is transferred from the protons to the electrons in the shock transition layer, leading naturally to a high minimum Lorentz factor for the latter. A low magnetisation favours the acceleration of particles in relativistic shocks. The shock co-acceleration scenario provides additional constraints on the set of parameters of a standard one-zone lepto-hadronic emission model, reducing its degeneracy. Values of the magnetic field strength of a few mG and minimum electron Lorentz factors of 10^3 to 10^4, required to provide a satisfactory description of the observed spectral energy distributions of extreme blazars, result here from first principles. While acceleration on a single standing shock is sufficient to reproduce the emission of most of the extreme-TeV sources we have examined, re-acceleration on a second shock appears needed for those objects with the hardest gamma-ray spectra. Emission from the accelerated proton population, with the same number density as the electrons but in a lower range of Lorentz factors, is strongly suppressed. Satisfactory self-consistent representations were found for the most prominent representatives of this new blazar class.

We report signatures of episodic accretion in young stellar objects (YSOs) that emerge in protobinary configurations in a gravoturbulent gas collapse. We find in most of these protobinary systems strong accretion bursts between the two companions with a recurrence time-scale of about 1 kyr. The accretion rate onto the secondary star typically exceeds that onto the primary with a peak value of 2 $\times 10^{-2}$ M$_{\odot}$ yr$^{-1}$ for the former and 6 $\times 10^{-3}$ M$_{\odot}$ yr$^{-1}$ for the latter. We propose that the secondary companion which remains more active in its episodes of accretion bursts, especially for the gas cores with subsonic velocity dispersion, may provide observational opportunities to find traces of episodic accretion in the surrounding gas of the embedded YSOs that are in a binary configuration. Also, protostars evolving as single objects in the same environment show fewer accretion bursts and all together a more steady mass growth history. The prestellar cores with subsonic velocity dispersion exhibit an order of magnitude more intense accretion bursts than in the case of cores with supersonic velocity dispersions. The latter shows the formation of some of the protobinaries in which the primary acts as a more actively accreting companion. This can support these binaries to become systems of extreme mass ratio. Moreover, the YSOs in binary configurations with small semi-major axis $a$ $\approx$ 50 au and high mass ratio $q$ > 0.7 support phases of intense episodic accretion. The eccentricity, however, seems to play no significant role in the occurrence of accretion bursts.

Close-in super-Earths are the most abundant exoplanets known. It has been hypothesized that they form in the inner regions of protoplanetary discs, out of the dust that may accumulate at the boundary between the inner region susceptible to the magneto-rotational instability (MRI) and an MRI-dead zone further out. In Paper I we presented a model for the viscous inner disc which includes heating due to both irradiation and MRI-driven accretion; thermal and non-thermal ionization; dust opacities; and dust effects on ionization. Here we examine how the inner disc structure varies with stellar, disc and dust parameters. For high accretion rates and small dust grains, we find that: (1) the main sources of ionization are thermal ionization and thermionic and ion emission; (2) the disc features a hot, high-viscosity inner region, and a local gas pressure maximum at the outer edge of this region (in line with previous studies); and (3) an increase in the dust-to-gas ratio pushes the pressure maximum outwards. Consequently, dust can accumulate in such inner discs without suppressing the MRI, with the amount of accumulation depending on the viscosity in the MRI-dead regions. Conversely, for low accretion rates and large dust grains, there appears to be an additional steady-state solution in which: (1) stellar X-rays become the main source of ionization; (2) MRI-viscosity is high throughout the disc; and (3) the pressure maximum ceases to exist. Hence, if planets form in the inner disc, larger accretion rates (and thus younger disks) are favoured.

The number of satellites in low-Earth orbit is increasing rapidly, and many tens of thousands of them are expected to be launched in the coming years. There is a strong concern among the astronomical community about the contamination of optical and near-infrared observations by satellite trails. We analyze the impact analysis of such constellations on optical and near-infrared astronomical observations in a rigorous and quantitative way, using updated constellation information, and considering imagers and spectrographs and their very different characteristics. We introduce an analytical method that allows us to rapidly and accurately evaluate the effect of a very large number of satellites, accounting for their magnitudes and the effect of trailing of the satellite image during the exposure. We use this to evaluate the impact on a series of representative instruments, including imagers (traditional narrow field instruments, wide-field survey cameras, and astro-photographic cameras) and spectrographs (long-slit and fibre-fed), taking into account their limiting magnitude. As already known (Walker et al. 2020), the effect of satellite trails is more damaging for high-altitude satellites, on wide-field instruments, or essentially during the first and last hours of the night. Thanks to their brighter limiting magnitudes, low- and mid-resolution spectrographs will be less affected, but the contamination will be at about the same level as that of the science signal, introducing additional challenges. High-resolution spectrographs will essentially be immune. We propose a series of mitigating measures, including one that uses the described simulation method to optimize the scheduling of the observations. We conclude that no single mitigation measure will solve the problem of satellite trails for all instruments and all science cases.

We present the results of nine simulations of radiatively-inefficient magnetically arrested disks (MADs) across different values of the black hole spin parameter $a_*$: $-0.9$, $-0.7$, $-0.5$, $-0.3$, 0, 0.3, 0.5, 0.7, and 0.9. Each simulation was run up to $t \gtrsim 100,000\,GM/c^3$ to ensure disk inflow equilibrium out to large radii. We find that the saturated magnetic flux level, and consequently also jet power, of MAD disks depends strongly on the black hole spin, confirming the results of Tchekhovskoy et al. (2012). Prograde disks saturate at a much higher relative magnetic flux and have more powerful jets than their retrograde counterparts. MADs with spinning black holes naturally launch jets with generalized parabolic profiles with width varying as a power of distance from the black hole. For distances up to $100GM/c^2$, the power-law index is $k \approx 0.27-0.42$. There is a strong correlation between the disk-jet geometry and the dimensionless magnetic flux, resulting in prograde systems displaying thinner equatorial accretion flows near the black hole and wider jets, compared to retrograde systems. Prograde and retrograde MADs also exhibit different trends in disk variability: accretion rate variability increases with increasing spin for $a_*>0$ and remains almost constant for $a_*\lesssim 0$, while magnetic flux variability shows the opposite trend. Jets in the MAD state remove more angular momentum from black holes than is accreted, effectively spinning down the black hole. If powerful jets from MAD systems in Nature are persistent, this loss of angular momentum will notably reduce the black hole spin over cosmic time.

Primordial black holes (PBHs) have been proposed to explain at least a portion of dark matter. Observations have put strong constraints on PBHs in terms of the fraction of dark matter which they can represent, $f_{\rm PBH}$, across a wide mass range -- apart from the stellar-mass range of $20M_\odot\lesssim M_{\rm PBH}\lesssim 100M_\odot$. In this paper, we explore the possibility that such PBHs could serve as point-mass lenses capable of altering the gravitational-wave (GW) signals observed from binary black hole (BBH) mergers along their line-of-sight. We find that careful GW data analysis could verify the existence of such PBHs based on the $fitting~factor$ and odds ratio analyses. When such a lensed GW signal is detected, we expect to be able to measure the redshifted mass of the lens with a relative error $\Delta M_{\rm PBH}/M_{\rm PBH}\lesssim0.3$. If no such lensed GW events were detected despite the operation of sensitive GW detectors accumulating large numbers of BBH mergers, it would translate into a stringent constraint of $f_{\rm PBH}\lesssim 10^{-2}-10^{-5}$ for PBHs with a mass larger than $\sim10M_\odot$ by the Einstein Telescope after one year of running, and $f_{\rm PBH}\lesssim 0.2$ for PBHs with mass greater than $\sim 50M_\odot$ for advanced LIGO after ten years of running.

In the stellar forming region NGC 2264 there are objects catalogued as hosting a transitional disk according to spectrum modeling. Four members of this set have optical and infrared light curves coming from the CoRoT and Spitzer telescopes. In this work, we try to simultaneously explain the light curves using the extinction of the stellar radiation and the emission of the dust inside the hole of a transitional disk. For the object Mon-296, we were successful. However, for Mon-314, and Mon-433 our evidence suggests that they host a pre-transitional disk. For Mon-1308 a new spectrum fitting using the 3D radiative transfer code Hyperion allows us to conclude that this object hosts a full disk instead of a transitional disk. This is in accord to previous work on Mon-1308 and with the fact that we cannot find a fit for the light curves using only the contribution of the dust inside the hole of a transitional disk.

Interstellar grains are known to be important actors in the formation of interstellar molecules such as H$_2$, water, ammonia, and methanol. It has been suggested that the so-called interstellar complex organic molecules (iCOMs) are also formed on the interstellar grain icy surfaces by the combination of radicals via reactions assumed to have an efficiency equal to unity. In this work, we aim to investigate the robustness or weakness of this assumption by considering the case of acetaldehyde (CH$_3$CHO) as a starting study case. In the literature, it has been postulated that acetaldehyde is formed on the icy surfaces via the combination of HCO and CH$_3$. Here we report new theoretical computations on the efficiency of its formation. To this end, we coupled quantum chemical calculations of the energetics and kinetics of the reaction CH$_3$ + HCO, which can lead to the formation of CH$_3$CHO or CO + CH$_4$. Specifically, we combined reaction kinetics computed with the Rice-Ramsperger-Kassel-Marcus (RRKM) theory (tunneling included) method with diffusion and desorption competitive channels. We provide the results of our computations in the format used by astrochemical models to facilitate their exploitation. Our new computations indicate that the efficiency of acetaldehyde formation on the icy surfaces is a complex function of the temperature and, more importantly, of the assumed diffusion over binding energy ratio $f$ of the CH$_3$ radical. If the ratio $f$ is $\geq$0.4, the efficiency is equal to unity in the range where the reaction can occur, namely between 12 and 30 K. However, if $f$ is smaller, the efficiency dramatically crashes: with $f$=0.3, it is at most 0.01. In addition, the formation of acetaldehyde is always in competition with that of CO + CH$_4$.

Both NASA's Solar Dynamics Observatory (SDO) and the JAXA/NASA Hinode mission include spectropolarimetric instruments designed to measure the photospheric magnetic field. SDO's Helioseismic and Magnetic Imager (HMI) emphasizes full-disk high-cadence and good spatial resolution data acquisition while Hinode's Solar Optical Telescope Spectro-Polarimeter (SOT-SP) focuses on high spatial resolution and spectral sampling at the cost of a limited field of view and slower temporal cadence. This work introduces a deep-learning system named SynthIA (Synthetic Inversion Approximation), that can enhance both missions by capturing the best of each instrument's characteristics. We use SynthIA to produce a new magnetogram data product, SynodeP (Synthetic Hinode Pipeline), that mimics magnetograms from the higher spectral resolution Hinode/SOT-SP pipeline, but is derived from full-disk, high-cadence, and lower spectral-resolution SDO/HMI Stokes observations. Results on held-out data show that SynodeP has good agreement with the Hinode/SOT-SP pipeline inversions, including magnetic fill fraction, which is not provided by the current SDO/HMI pipeline. SynodeP further shows a reduction in the magnitude of the 24-hour oscillations present in the SDO/HMI data. To demonstrate SynthIA's generality, we show the use of SDO/AIA data and subsets of the HMI data as inputs, which enables trade-offs between fidelity to the Hinode/SOT-SP inversions, number of observations used, and temporal artifacts. We discuss possible generalizations of SynthIA and its implications for space weather modeling. This work is part of the NASA Heliophysics DRIVE Science Center (SOLSTICE) at the University of Michigan under grant NASA 80NSSC20K0600E, and will be open-sourced.

We consider a recent approach to the construction of gauge-invariant relational observables in gravity in the context of cosmological perturbation theory. These observables are constructed using a field-dependent coordinate system, which we take to be geodesic lightcone coordinates. We show that the observables are gauge-independent in the fully non-linear theory, and that they have the expected form when one adopts the geodesic lightcone gauge for the metric. We give explicit expressions for the Sasaki-Mukhanov variable at linear order, and the Hubble rate -- as measured both by geodesic observers and by observers co-moving with the inflaton -- to second order. Moreover, we show that the well-known linearised equations of motion for the Sasaki-Mukhanov variable and the scalar constraint variables follow from the gauge-invariant Einstein equations.

In extensions of the Standard Model with no dimensionful parameters the electroweak phase transition can be delayed to temperatures of order 100 MeV. Then the chiral phase transition of QCD could proceed with 6 massless quarks. The top-quark condensate destabilizes the Higgs potential through the Yukawa interaction, triggering the electroweak transition. Based on the symmetries of massless QCD, it has been argued that the chiral phase transition is first order. We point out that the top-Higgs Yukawa interaction is non-perturbatively large at the QCD scale, and that its effect on the chiral phase transition may not be negligible, violating some of the symmetries of massless QCD. A symmetry breaking top-quark condensation would then happen in a second-order phase transition, a symmetry-breaking first-order transition could occur in the light-quark sector.

Understanding granular materials' aging poses a substantial challenge: Grain contacts form networks with complex topologies, and granular flow is far from equilibrium. In this letter, we experimentally measure a three-dimensional granular system's reversibility and aging under cyclic compression. We image the grains using a refractive-index-matched fluid, then analyze the images using the artificial intelligence of variational autoencoders. These techniques allow us to track all the grains' translations and three-dimensional rotations with accuracy sufficient to infer contact-point sliding and rolling. Our observations reveal unique roles played by three-dimensional rotations in granular flow, aging, and energy dissipation. First, we find that granular rotations dominate the bulk dynamics, penetrating more deeply into the granular material than translations do. Second, sliding and rolling do not exhibit aging across the experiment, unlike translations. Third, aging appears not to minimize energy dissipation, according to our experimental measurements of rotations, combined with soft-sphere simulations. The experimental tools, analytical techniques, and observations that we introduce expose all the degrees of freedom of the far-from-equilibrium dynamics of granular flow.

The excitation and further sustenance of large-scale magnetic fields in rotating astrophysical systems, including planets, stars and galaxies, is generally thought to involve a fluid magnetic dynamo effect driven by helical magnetohydrodynamic turbulence. While this scenario is appealing on general grounds, it however currently remains largely unconstrained, notably because a fundamental understanding of the nonlinear asymptotic behaviour of large-scale fluid magnetism in the astrophysically-relevant but treacherous regime of large magnetic Reynolds number $Rm$ is still lacking. We explore this problem using local high-resolution simulations of turbulent magnetohydrodynamics driven by an inhomogeneous helical forcing generating a sinusoidal profile of kinetic helicity, mimicking the hemispheric distribution of kinetic helicity in rotating turbulent fluid bodies. We identify a transition at large $Rm$ to an asymptotic nonlinear state, followed up to $Rm\simeq 3\times 10^3$, characterized by an asymptotically small resistive dissipation of magnetic helicity, by its efficient spatial redistribution across the equator through turbulent fluxes driven by the hemispheric distribution of kinetic helicity, and by the presence in the tangled dynamical magnetic field of plasmoids typical of reconnection at large $Rm$.

"Glitches" -- transient noise artifacts in the data collected by gravitational wave interferometers like LIGO and Virgo -- are an ever-present obstacle for the search and characterization of gravitational wave signals. With some having morphology similar to high mass, high mass-ratio, and extreme-spin binary black hole events, they limit sensitivity to such sources. They can also act as a contaminant for all sources, requiring targeted mitigation before astrophysical inferences can be made. We propose a data driven, parametric model for frequently encountered glitch types using probabilistic principal component analysis. As a noise analog of parameterized gravitational wave signal models, it can be easily incorporated into existing search and detector characterization techniques. We have implemented our approach with the open source glitschen package. Using LIGO's currently most problematic glitch types, the 'blip' and 'tomte', we demonstrate that parametric models of modest dimension can be constructed and used for effective mitigation in both frequentist and Bayesian analyses.

We propose a scenario that the Electroweak-Skyrmion, a solitonic object made of the Higgs field and the electroweak gauge fields, is identified as an asymmetric dark matter. In this scenario, the relic abundance of the dark matter is related to the baryon asymmetry of the Universe through a sphaleron-like process. We show that the observed ratio of dark matter abundance to the baryon asymmetry can be explained by this scenario with an appropriate choice of model parameters that is allowed by currently available experimental constraints.

We present our experience with the modernization on the GR-MHD code BHAC, aimed at improving its novel hybrid (MPI+OpenMP) parallelization scheme. In doing so, we showcase the use of performance profiling tools usable on x86 (Intel-based) architectures. Our performance characterization and threading analysis provided guidance in improving the concurrency and thus the efficiency of the OpenMP parallel regions. We assess scaling and communication patterns in order to identify and alleviate MPI bottlenecks, with both runtime switches and precise code interventions. The performance of optimized version of BHAC improved by $\sim28\%$, making it viable for scaling on several hundreds of supercomputer nodes. We finally test whether porting such optimizations to different hardware is likewise beneficial on the new architecture by running on ARM A64FX vector nodes.

We apply the gravity-thermodynamics conjecture, namely the first law of thermodynamics on the Universe horizon, but using the generalized Kaniadakis entropy instead of the standard Bekenstein-Hawking one. The former is a one-parameter generalization of the classical Boltzmann-Gibbs-Shannon entropy, arising from a coherent and self-consistent relativistic statistical theory. We obtain new modified cosmological scenarios, namely modified Friedmann equations, which contain new extra terms that constitute an effective dark energy sector depending on the single model Kaniadakis parameter $K$. We investigate the cosmological evolution, by extracting analytical expressions for the dark energy density and equation-of-state parameters and we show that the Universe exhibits the usual thermal history, with a transition redshift from deceleration to acceleration at around 0.6. Furthermore, depending on the value of $K$, the dark energy equation-of-state parameter deviates from $\Lambda$CDM cosmology at small redshifts, while lying always in the phantom regime, and at asymptotically large times the Universe always results in a dark-energy dominated, de Sitter phase. Finally, even in the case where we do not consider an explicit cosmological constant the resulting cosmology is very interesting and in agreement with the observed behavior.

Upcoming observing campaigns with improved detectors will yield numerous detections of gravitational waves from neutron star binary inspirals. Rare loud signals together with numerous signals of moderate strength promise stringent constraints on the properties of neutron star matter, with a projected radius statistical uncertainty of $50-200$m with ${\cal{O}}(2000)$ sources. Given this precision we revisit all analysis assumptions and identify sources of systematic errors, quantify their impact on radius extraction, and discuss their relative importance and ways to mitigate them.

We present new rotating vacuum configurations endowed with both dynamical torsion and nonmetricity fields in the framework of Metric-Affine gauge theory of gravity. For this task, we consider scalar-flat Weyl-Cartan geometries and obtain an axisymmetric Kerr-Newman solution in the decoupling limit between the orbital and the spin angular momentum. The corresponding Kerr-Newman-de Sitter solution is also compatible with a cosmological constant and additional electromagnetic fields.

Particulate dark matter captured by a population of neutron stars distributed around the galactic center while annihilating through long-lived mediators can give rise to an observable neutrino flux. We examine the prospect of an idealized gigaton detector like IceCube/KM3Net in probing such scenarios. Within this framework, we report an improved reach in the dark matter nucleon cross-section below the current limits for dark matter masses in the ${\rm TeV - PeV}$ range.