Papers for Wednesday, Apr 13 2022

We present a study of the stellar populations of globular clusters (GCs) in the Virgo Cluster core with a homogeneous spectroscopic catalog of 692 GCs within a major axis distance $R_{\rm maj} = $ 840 kpc from M87. We investigate radial and azimuthal variations in the mean age, total metallicity, [Fe/H], and $\alpha$-element abundance, of blue (metal-poor) and red (metal-rich) GCs using their co-added spectra. We find that the blue GCs have a steep radial gradient in [Z/H] within $R_{\rm maj} =$ 165 kpc, with roughly equal contributions from [Fe/H] and [$\alpha$/Fe], and flat gradients beyond. By contrast, the red GCs show a much shallower gradient in [Z/H], which is entirely driven by [Fe/H]. We use GC-tagged Illustris simulations to demonstrate an accretion scenario where more massive satellites (with more metal- and $\alpha$-rich GCs) sink further into the central galaxy than less massive ones, and where the gradient flattening occurs because of the low GC occupation fraction of low-mass dwarfs disrupted at larger distances. The dense environment around M87 may also cause the steep [$\alpha$/Fe] gradient of the blue GCs, mirroring what is seen in the dwarf galaxy population. The progenitors of red GCs have a narrower mass range than those of blue GCs, which makes their gradients shallower. We also explore spatial inhomogeneity in GC abundances, finding that the red GCs to the northwest of M87 are slightly more metal-rich. Future observations of GC stellar population gradients will be useful diagnostics of halo merger histories.

We present measurements of broad emission lines and virial estimates of supermassive black hole masses ($M_{BH}$) for a large sample of ultra-hard X-ray selected active galactic nuclei (AGNs) as part of the second data release of the BAT AGN Spectroscopic Survey (BASS/DR2). Our catalog includes $M_{BH}$ estimates for a total 689 AGNs, determined from the H$\alpha$, H$\beta$, $MgII\lambda2798$, and/or $CIV\lambda1549$ broad emission lines. The core sample includes a total of 512 AGNs drawn from the 70-month Swift/BAT all-sky catalog. We also provide measurements for 177 additional AGNs that are drawn from deeper Swift/BAT survey data. We study the links between $M_{BH}$ estimates and line-of-sight obscuration measured from X-ray spectral analysis. We find that broad H$\alpha$ emission lines in obscured AGNs ($\log (N_{\rm H}/{\rm cm}^{-2})> 22.0$) are on average a factor of $8.0_{-2.4}^{+4.1}$ weaker, relative to ultra-hard X-ray emission, and about $35_{-12}^{~+7}$\% narrower than in unobscured sources (i.e., $\log (N_{\rm H}/{\rm cm}^{-2}) < 21.5$). This indicates that the innermost part of the broad-line region is preferentially absorbed. Consequently, current single-epoch $M_{BH}$ prescriptions result in severely underestimated ($>$1 dex) masses for Type 1.9 sources (AGNs with broad H$\alpha$ but no broad H$\beta$) and/or sources with $\log (N_{\rm H}/{\rm cm}^{-2}) > 22.0$. We provide simple multiplicative corrections for the observed luminosity and width of the broad H$\alpha$ component ($L[{\rm b}{\rm H}\alpha]$ and FWHM[bH$\alpha$]) in such sources to account for this effect, and to (partially) remedy $M_{BH}$ estimates for Type 1.9 objects. As key ingredient of BASS/DR2, our work provides the community with the data needed to further study powerful AGNs in the low-redshift Universe.

The characterization of the dynamical state of galaxies up to z~7 is crucial for constraining the mechanisms driving the mass assembly in the early Universe. However, it is unclear whether the data quality of current and future observations is sufficient to perform a solid dynamical analysis. This paper defines the angular resolution and S/N required for a robust characterization of the dynamical state of galaxies up to the EoR. The final aim is to help design spatially-resolved surveys targeting emission lines of primeval galaxies. We investigate the [CII]-158um emission from z~6-7 LBGs from the SERRA cosmological simulation, covering a range of dynamical states: from disks to major mergers. We create ALMA mock observations with various data quality and apply the kinematic classification methods used in the literature. These tests allow us to quantify the performances of such methods as a function of angular resolution and S/N. We find that barely-resolved observations do not allow the correct dynamical characterization of a galaxy, resulting in the misclassification of all disks in our sample. However, even when using spatially-resolved observations with data quality typical of high-z galaxies, the standard kinematic classification methods, based on the analysis of the moment maps, fail to distinguish a merger from a disk. The high angular resolution and S/N needed to apply these standard methods successfully can be achieved with current data only for a handful of bright galaxies. We propose a new classification method, called PVsplit, that quantifies the asymmetries and morphological features in position-velocity diagrams using three empirical parameters. We test PVsplit on our mock data concluding that it can predict whether a galaxy is a disk or a merger provided that S/N $\gtrsim10$, and the major axis is covered by $\gtrsim3$ independent resolution elements.

NLTT 5306 is a post-common envelope binary made up of a white dwarf host and brown dwarf companion that has shown evidence of inflation and active mass donation despite not filling its Roche lobe. Two proposed mechanisms for the brown dwarf's inflation are magnetic interactions and a high metallicity, cloudy atmosphere. We present moderate resolution ($R\lesssim2000$) $J$ band Keck/NIRSPEC observations of this system. These phase-resolved data allow us to constrain differences between atmospheric parameters of the day- and night-side of the brown dwarf. Our day- and night-side effective temperature measurements are consistent, in agreement with the brightness temperatures measurements from Casewell et al. 2021a. The day-side favors a slightly lower surface gravity, perhaps stemming from the material streaming between the two objects. Finally, our data show a preference for low metallicity models. This would be expected from the system's old age, but provides direct evidence that a high metallicity, cloudy brown dwarf atmosphere is not responsible for the witnessed inflation. These results strengthen the case for magnetic interactions leading to inflation of NLTT 5306 B.

We present observational constraints on the galaxy-halo connection, focusing particularly on galaxy assembly bias, from a novel combination of counts-in-cylinders statistics, $P(N_{\rm{CIC}})$, with the standard measurements of the projected two-point correlation function, $w_{\rm{p}}(r_{\rm{p}})$, and number density, $n_{\rm{gal}}$, of galaxies. We measure $n_{\rm{gal}}$, $w_{\rm{p}}(r_{\rm{p}})$ and $P(N_{\rm{CIC}})$ for volume-limited, luminosity-threshold samples of galaxies selected from SDSS DR7, and use them to constrain halo occupation distribution (HOD) models, including a model in which galaxy occupation depends upon a secondary halo property, namely halo concentration. We detect significant positive central assembly bias for the $M_r<-20.0$ and $M_r<-19.5$ samples. Central galaxies preferentially reside within haloes of high concentration at fixed mass. Positive central assembly bias is also favoured in the $M_r<-20.5$ and $M_r<-19.0$ samples. We find no evidence of central assembly bias in the $M_r<-21.0$ sample. We observe only a marginal preference for negative satellite assembly bias in the $M_r<-20.0$ and $M_r<-19.0$ samples, and non-zero satellite assembly bias is not indicated in other samples. Our findings underscore the necessity of accounting for galaxy assembly bias when interpreting galaxy survey data, and demonstrate the potential of count statistics in extracting information from the spatial distribution of galaxies, which could be applied to both galaxy-halo connection studies and cosmological analyses.

We report 4 new pulsars discovered in the core-collapsed globular cluster (GC) NGC 6624 by the TRAPUM Large Survey Project with the MeerKAT telescope. All of the new pulsars found are isolated. PSR J1823$-$3021I and PSR J1823$-$3021K are millisecond pulsars with period of respectively 4.319 ms and 2.768 ms. PSR J1823$-$3021J is mildly recycled with a period of 20.899 ms, and PSR J1823$-$3022 is a long period pulsar with a period of 2.497 s. The pulsars J1823$-$3021I, J1823$-$3021J, and J1823$-$3021K have position and dispersion measure (DM) compatible with being members of the GC and are therefore associated with NGC 6624. Pulsar J1823$-$3022 is the only pulsar bright enough to be re-detected in archival observations of the cluster. This allowed the determination of a timing solution that spans over two decades. It is not possible at the moment to claim the association of pulsar J1823$-$3022 with the GC given the long period and large offset in position ($\sim 3$ arcminutes) and DM (with a fractional difference of 11 percent compared the average of the pulsars in NGC 6624). The discoveries made use of the beamforming capability of the TRAPUM backend to generate multiple beams in the same field of view which allows sensitive searches to be performed over a few half-light radii from the cluster center and can simultaneously localise the discoveries. The discoveries reflect the properties expected for pulsars in core-collapsed GCs.

GW190425 was the second gravitational wave (GW) signal compatible with a binary neutron star (BNS) merger detected by the Advanced LIGO and Advanced Virgo detectors. Despite intense follow-up campaigns, no electromagnetic counterpart was identified. Whether the associated kilonova was too dim or the localisation area too broad is still an open question. We simulate 28 BNS mergers with the chirp mass of GW190425 and spanning a mass ratio $1 \leq q \leq 1.67$, using numerical-relativity simulations with finite temperature, composition dependent nuclear equation of state (EOS) and neutrino radiation. The energy emitted in GWs is $\lesssim 0.083 M_{\odot} c^2$ with a peak luminosity of $1.1-2.4 \times 10^{58} {\rm erg~s^{-1}}/(1+q)^2$. Dynamical ejecta and disc mass are relatively small, the former ranging between $5 \times 10^{-6}$ and $\sim 10^{-3}~M_{\odot}$ and the latter between $10^{-5}$ and $0.1~M_{\odot}$. Asymmetric mergers, especially in the case of stiff EOS, are able to unbind more matter and to form heavier discs compared to equal mass binaries. The angular momentum of the disc is $8-10 M_{\odot}~GM_{\rm disc}/c$ over three orders of magnitude in $M_{\rm disc}$. While the associated nucleosynthesis shows no peculiarity, the simulated kilonovae are relatively dim compared with the GW170817 event. In particular, for distances compatible with GW190425, we find AB magnitudes always dimmer than $\sim20~{\rm mag}$ for the $B$, $r$ and $K$ bands, with brighter kilonovae associated to more asymmetric binaries and stiffer EOS. We suggest that, even assuming a good coverage of GW190425's sky location, the kilonova signal could hardly have been detected by present wide-field surveys and no firm constraints on the binary parameters or neutron star (NS) EOS can be argued from the lack of the detection.

The strongest existing constraints on primordial black holes with masses in the range of $m_{\rm BH} \sim 10^{15}-10^{17} \, {\rm g}$ have been derived from measurements of the local cosmic-ray electron-positron flux by Voyager 1, and MeV-scale gamma-ray observations of the Inner Galaxy by COMPTEL and INTEGRAL. In this paper, we evaluate the sensitivity of future MeV-scale gamma-ray telescopes such as e-ASTROGAM or AMEGO to Hawking radiation. We show that such an instrument would be able to provide the strongest constraints on black holes in the mass range of $m_{\rm BH} \sim (0.6-20) \times 10^{16} \, {\rm g}$, typically exceeding current constraints by approximately two orders of magnitude. In scenarios in which the observed 511 keV excess is the result of Hawking radiation, we find that e-ASTROGAM or AMEGO would not only be able to detect the Hawking radiation from the Inner Galaxy, but could precisely measure the abundance and mass distribution of the black holes responsible for this signal.

I explore the properties of "dark gaps" - regions in quasar absorption spectra without significant transmission - with several simulations from the Cosmic Reionization On Computers (CROC) project. CROC simulations in largest available boxes (120 cMpc) come close to matching both the distribution of mean opacities and the frequency of dark gaps, but alas not in the same model: the run that matches the mean opacities fails to contain enough dark gaps and vice versa.:( Never-the-less, the run that matches the dark gap distributions serves as a counter-example to claims in the literature that the dark gap statistics requires a late end to reionization - in that run reionization ends at z=6.7 (likely too early). While multiple factors contribute to the frequency of large dark gaps in the simulations, the primary factor that controls the overall shape of the dark gap distribution is the ionization level in voids - the lowest density regions produce the highest transmission spikes that terminate long gaps. As the result, the dark gap distribution correlates strongly with the fraction of the spectrum above the gap detection threshold, the observed distribution is matched by the simulation in which this fraction is 2%. Hence, the gap distribution by itself does not constrain the timing of reionization.

Extreme mass ratio inspirals (EMRIs) are compact binary systems characterized by a mass-ratio $q=m/M$ in the range $~10^{-9}-10^{-4}$ and represent primary gravitational wave (GW) sources for the forthcoming Laser Interferometer Space Antenna (LISA). While their standard formation channel involves relaxation processes deflecting compact objects on very low angular momentum orbits around the central massive black hole, a number of alternative formation channels has been proposed, including binary tidal break-up, migration in accretion disks and secular and chaotic dynamics around a massive black hole binary (MBHB). In this work, we take an extensive closer look at this latter scenario, investigating how EMRIs can be triggered by a MBHBs, formed in the aftermath of galaxy mergers. By employing a suite of relativistic three-body simulations, we evaluate the efficiency of EMRI formation for different parameters of the MBHB, assessing the importance of both secular and chaotic dynamics. By modelling the distribution of compact objects in galaxy nuclei, we estimate the resulting EMRI formation rate, finding that EMRI are produced in a sharp burst, with peak rates that are 10-100 times higher than the standard two-body relaxation channel, lasting for 10$^6$--10$^8$ years. By coupling our results with an estimate of the cosmic MBHB merger rate, we finally forecast that LISA could observe ${\cal O}(10)$ EMRIs per year formed by this channel.

The driving of turbulence in galaxies is deeply connected with the physics of feedback, star formation, outflows, accretion, and radial transport in disks. The velocity dispersion of gas in galaxies therefore offers a promising observational window into these processes. However, the relative importance of each of these mechanisms remains controversial. In this work we revisit the possibility that turbulence on galactic scales is driven by the direct impact of accreting gaseous material on the disk. We measure this effect in a disk-like star-forming galaxy in IllustrisTNG, using the high-resolution cosmological magnetohydrodynamical simulation TNG50. We employ Lagrangian tracer particles with a high time cadence of only a few Myr to identify accretion and other events, such as star formation, outflows, and movement within the disk. The energies of particles as they arrive in the disk are measured by stacking the events in bins of time before and after the event. The average effect of each event is measured on the galaxy by fitting explicit models for the kinetic and turbulent energies as a function of time in the disk. These measurements are corroborated by measuring the cross-correlation of the turbulent energy in the different annuli of the disk with other time series, and searching for signals of causality, i.e. asymmetries in the cross-correlation across zero time lag. We find that accretion contributes to the large-scale turbulent kinetic energy even if it is not the dominant driver of turbulence in this $\sim 5 \times 10^{9} M_\odot$ stellar mass galaxy. Extrapolating this finding to a range of galaxy masses, we find that there are regimes where energy from direct accretion may dominate the turbulent energy budget, particularly in disk outskirts, galaxies less massive than the Milky Way, and at redshift $\sim 2$.

Agriculture is one of the oldest forms of technology on Earth. The cultivation of plants requires a terrestrial planet with active hydrological and carbon cycles and depends on the availability of nitrogen in soil. The technological innovation of agriculture is the active management of this nitrogen cycle by applying fertilizer to soil, at first through the production of manure excesses but later by the Haber-Bosch industrial process. The use of such fertilizers has increased the atmospheric abundance of nitrogen-containing species such as NH$_3$ and N$_2$O as agricultural productivity intensifies in many parts of the world. Both NH$_3$ and N$_2$O are effective greenhouse gases, and the combined presence of these gases in the atmosphere of a habitable planet could serve as a remotely detectable spectral signature of technology. Here we use a synthetic spectral generator to assess the detectability of NH$_3$ and N$_2$O that would arise from present-day and future global-scale agriculture. We show that present-day Earth abundances of NH$_3$ and N$_2$O would be difficult to detect but hypothetical scenarios involving a planet with 30-100 billion people could show a change in transmittance of about 50-70% compared to pre-agricultural Earth. These calculations suggest the possibility of considering the simultaneous detection of NH$_3$ and N$_2$O in an atmosphere that also contains H$_2$O, O$_2$, and CO$_2$ as a technosignature for extraterrestrial agriculture. The technology of agriculture is one that could be sustainable across geologic timescales, so the spectral signature of such an "ExoFarm" is worth considering in the search for technosignatures.

The spectra of active galactic nuclei exhibit broad-emission lines that presumably originate in the Broad-Line Region (BLR) with gaseous-dusty clouds in a predominantly Keplerian motion around the central black hole. Signatures of both inflow and outflow motion are frequently seen. The dynamical character of BLR is consistent with the scenario that has been branded as the Failed Radiatively Accelerated Dusty Outflow (FRADO; Czerny & Hryniewicz 2011). In this scheme, frequent high-velocity impacts of BLR clouds falling back onto the underlying accretion disk are predicted. The impact velocities depend mainly on the black-hole mass, accretion rate, and metallicity and they range from a few km s$^{-1}$ up to thousands of km s$^{-1}$. Formation of strong shocks due to the collisions can give rise to the production of relativistic particles and associated radiation signatures. In this work, the non-thermal radiation generated in this process is investigated, and the spectral energy distributions for different parameter sets are presented. We find that the non-thermal processes caused by the impacts of clouds can lead to emission in the X-ray and the gamma-ray bands, playing the cloud density and metallicity a key role.

We explore how the assumption of ionization equilibrium modulates the modeled intergalactic medium (IGM) at the end of the hydrogen Epoch of Reionization using the cosmological radiation hydrodynamic \textsc{Technicolor Dawn} simulation. In neutral and partially-ionized regions where the metagalactic ultraviolet background (UVB) is weak, the ionization timescale $t_\mathrm{ion}\equiv \Gamma^{-1}$ exceeds the Hubble time. Assuming photoionization equilibrium in such regions artificially boosts the ionization rate, accelerating reionization. By contrast, the recombination time $t_\mathrm{rec} < t_\mathrm{ion}$ in photoionized regions, with the result that assuming photoionization equilibrium artificially increases the neutral hydrogen fraction. Using snapshots between $8 \geq z \geq 5$, we compare the predicted Lyman-$\alpha$ forest flux power spectrum with and without the assumption of ionization equilibrium. Small scales ($k > 0.1$ rad s km$^{-1}$) exhibit reduced power from $7 \leq z \leq 5.5$ in the ionization equilibrium case while larger scales are unaffected. This occurs for the same reasons: ionization equilibrium artificially suppresses the neutral fraction in self-shielded gas and boosts ionizations in voids, suppressing small-scale fluctuations in the ionization field. When the volume-averaged neutral fraction drops below $10^{-4}$, the signature of non-equilibrium ionizations on the Lyman-$\alpha$ forest (LAF) disappears. Comparing with recent observations indicates that these non-equilibrium effects are not yet observable in the LAF flux power spectrum.

Improving the understanding of the processes governing small-scale nonlinear clustering is a necessary task for interpreting upcoming high-quality cosmological data, as it will allow one to break degeneracies and obtain tight neutrino mass and warm dark matter constraints from large-scale structure probes. The Sejong Suite, an extensive collection of state-of-the-art high-resolution cosmological hydrodynamical simulations, has been intended with this primary goal in mind. Spanning a large number of cosmological and astrophysical parameters (especially suitable for the dark sector), and organized into three main categories (Grid Suite, Supporting Suite, and Systematics Suite), the release may be useful for a broader variety of cosmological and astrophysical purposes - while primarily developed for Lyman-Alpha (LyA) forest studies. In particular, the overall architecture of the Grid Suite has been designed to achieve an equivalent resolution up to 3x3328^3=110 billion particles in a 100 Mpc/h box, corresponding to a 30 kpc/h mean grid resolution, which ensures convergence on LyA flux statistics closer to the desired 1.0% level that data from surveys such as the Dark Energy Spectroscopic Instrument (DESI) will provide. Here, we briefly highlight the main characteristics, improvements, and novelties of the Sejong Suite, as well as ongoing and future applications.

Resolved dust continuum and CO line ALMA imaging, and in some cases detection of H$\alpha$ emission, hint that young massive planets are abundant at wide separations in protoplanetary discs. Here, we show how these observations can probe the runaway phase of planetary growth in the Core Accretion theory. Planets in this phase have the right range of masses to account for the predominantly moderate contrast gaps and rings seen in ALMA observations. However, we find that these planets gain mass and migrate inward very rapidly. As a result, the phase when they could produce gaps with properties similar to those observed is very short, i.e., $t_{\rm gap} \lesssim 0.1$~Myr, independently of the disc viscosity parameter. This would require many tens to hundreds of gas giant planets to be born per ALMA system, violating the available mass budget of solids in realistic discs. This also predicts preponderance of discs with very wide gaps or complete inner disc holes, which is not observed. We show that suppression of both planet accretion and migration by a factor of at least ten is a possible solution to these serious problems. Future population synthesis models of planet formation should aim to address both exoplanetary data of older discless planetary systems and ALMA discs with embedded planets in one framework.

In response to the challenges presented by high reviewer workloads in traditional panel reviews and increasing numbers of submitted proposals, ALMA implemented distributed peer review to assess the majority of proposals submitted to the Cycle 8 Main Call. In this paper, we present an analysis of this review process. Over 1000 reviewers participated in the process to review 1497 proposals, making it the largest implementation of distributed peer review to date, and marking the first time this process has been used to award the majority of observing time at an observatory. We describe the process to assign proposals to reviewers, analyze the nearly 15,000 ranks and comments submitted by reviewers to identify any trends and systematics, and gather feedback on the process from reviewers and Principal Investigators (PIs) through surveys. Approximately 90% of the proposal assignments were aligned with the expertise of the reviewer, as measured both by the expertise keywords provided by the reviewers and the reviewers' self-assessment of their expertise on their assigned proposals. PIs rated 73% of the individual review comments as helpful, and even though the reviewers had a broad range of experience levels, PIs rated the quality of the comments received from students and senior researchers similarly. The primary concerns raised by PIs were the quality of some reviewer comments and high dispersions in the ranks. The ranks and comments are correlated with various demographics to identify the main areas in which the review process can be improved in future cycles.

We present observations of three-dimensional magnetic power spectra in wavevector space to investigate the anisotropy and scalings of sub-Alfv\'enic solar wind turbulence in low$-\beta_p$ plasma at magnetohydrodynamic (MHD) scale using the Magnetospheric Multiscale spacecraft. The magnetic power distributions are organized in a new coordinate determined by wavevectors (k) and background magnetic field ($b_0$) in Fourier space. This study utilizes two approaches to determine wavevectors: the singular value decomposition method and multi-spacecraft timing analysis. The combination of both methods allows an examination of magnetic field fluctuation properties in terms of mode compositions without spatiotemporal hypothesis. Observations show that fluctuations ($\delta B_{\perp1}$) in the direction perpendicular to k and $b_0$ prominently cascade perpendicular to $b_0$, and such anisotropy increases with wavenumber. The reduced power spectra of $\delta B_{\perp1}$ follow Goldreich-Sridhar scalings: $P(k_\perp)\sim k_\perp^{-5/3}$ and $P(k_{||}) \sim k_{||}^{-2}$. In contrast, fluctuations within $kb_0$ plane show isotropic behaviors: perpendicular power distributions are approximately the same as parallel distributions. The reduced power spectra of fluctuations within $kb_0$ plane follow the scalings: $P(k_\perp)\sim k_\perp^{-3/2}$ and $P(k_{||})\sim k_{||}^{-3/2}$. Comparing frequency-wavevector spectra with theoretical dispersion relations of MHD modes, we find that $\delta B_{\perp1}$ are probably associated with Alfv\'en modes. On the other hand, magnetic field fluctuations within $kb_0$ plane more likely originate from fast modes in low-$\beta_p$ plasma based on their isotropic behaviors. The observations of anisotropy and scalings of different magnetic field components are consistent with the predictions of current compressible MHD theory.

Large potentially hazardous asteroids (PHAs) are capable of causing a global catastrophe in the event of a planetary collision. Thus, rapid assessment of such an object's physical characteristics is crucial for determining its potential risk scale. We treated the near-Earth asteroid (99942) Apophis as a newly discovered object during its 2020-2021 close-approach as part of a mock planetary defense exercise. The object was detected by the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), and data collected by the two active bands (3.4 ${\mu}$m and 4.6 ${\mu}$m) were analyzed using thermal and thermophysical modeling. Our results indicate that Apophis is an elongated object with an effective spherical diameter D$_{eff}$ = 340 $\pm$ 70 m, a geometric visual albedo p$_{V}$ = 0.31 $\pm$ 0.09, and a thermal inertia $\Gamma$ $\sim$ 150 - 2850 Jm$^{-2}$s$^{-0.5}$K$^{-1}$ with a best-fit value of 550 Jm$^{-2}$s$^{-0.5}$K$^{-1}$. NEOWISE "discovery" observations reveal that (99942) Apophis is a potentially hazardous asteroid that would likely cause damage at a regional level and not a global one.

The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the MeV to the Planck scale. However, the range of potential cosmological applications of gravitational wave observations extends well beyond these two objectives. This publication presents a summary of the state of the art in LISA cosmology, theory and methods, and identifies new opportunities to use gravitational wave observations by LISA to probe the universe.

It is well known that the power spectrum is not able to fully characterize the statistical properties of non-Gaussian density fields. Recently, many different statistics have been proposed to extract information from non-Gaussian cosmological fields that perform better than the power spectrum. The Fisher matrix formalism is commonly used to quantify the accuracy with which a given statistic can constrain the value of the cosmological parameters. However, these calculations typically rely on the assumption that the likelihood of the considered statistic follows a multivariate Gaussian distribution. In this work we follow Sellentin & Heavens (2017) and use two different statistical tests to identify non-Gaussianities in different statistics such as the power spectrum, bispectrum, marked power spectrum, and wavelet scatering transform (WST). We remove the non-Gaussian components of the different statistics and perform Fisher matrix calculations with the \textit{Gaussianized} statistics using Quijote simulations. We show that constraints on the parameters can change by a factor of $\sim 2$ in some cases. We show with simple examples how statistics that do not follow a multivariate Gaussian distribution can achieve artificially tight bounds on the cosmological parameters when using the Fisher matrix formalism. We think that the non-Gaussian tests used in this work represent a powerful tool to quantify the robustness of Fisher matrix calculations and their underlying assumptions. We release the code used to compute the power spectra, bispectra, and WST that can be run on both CPUs and GPUs.

We hereby report the discovery of ATLAS17jrp as an extraordinary TDE in star-forming galaxy SDSSJ162034.99+240726.5 in our recent sample of mid-infrared outbursts in nearby galaxies. Its optical/UV light curves rise to a peak luminosity $\sim1.06\times10^{44}\rm\,erg\,s^{-1}$ in about a month and then decay as $\rm t^{-5/3}$ with a roughly constant temperature around 19000~K, and the optical spectra show a blue continuum and very broad Balmer lines with FWHM$\sim$15000 km/s which gradually narrowed to 1400 km/s within 4 years, all agreeing well with other optical TDEs. A delayed and rapidly rising X-ray flare with a peak luminosity $\rm \sim 1.27\times10^{43}\,erg\,s^{-1}$ was detected at $\rm \sim$ 170 days after the optical peak. The high MIR luminosity of ATLAS17jrp ($\sim2\times10^{43} \rm\,erg\,s^{-1}$) has revealed a distinctive dusty environment with covering factor as high as $\sim0.2$, that is comparable with that of torus in active galactic nuclei but at least one order of magnitude higher than normal optical TDEs. Therefore, ATLAS17jrp turns out to be one of the rare unambiguous TDE found in star-forming galaxies and its high dust covering factor implies that the dust extinction could play an important role in the absence of optical TDEs in star-forming galaxies.

As the only known intelligent civilization, human beings are always curious about the existence of other communicating extraterrestrial intelligent civilizations (CETIs). Based on the latest astrophysical information, we carry out Monte Carlo simulations to estimate the number of possible CETIs within our Galaxy and the communication probability among them. Two poorly known parameters have a great impact on the results. One is the probability of life appearing on terrestrial planets and eventually evolving a into CETI ($f_c$), and the other determines at what stage of their host star's evolution CETIs would be born ($F$). In order to ensure the completeness of the simulation, we consider a variety of combinations of $f_c$ and $F$. Our results indicate that for optimistic situations (e.g. $F=25\%$ and $f_c=0.1\%$), there could be $42777_{-369}^{+267}$ CETIs and they need to survive for $3_{-2}^{+17}$ yr ($2000_{-1400}^{+2000}$ yr) to achieve one-way communication (two-way communication). In this case, human beings need to survive $0.3_{-0.298}^{+0.6}$ Myr to receive one alien signal. For pessimistic situations (e.g. $F=75\%$ and $f_c=0.001\%$), only $111_{-17}^{+28}$ CETIs could be born and they need to survive for $0.8_{-0.796}^{+1.2}$ Myr ($0.9_{-0.88}^{+4.1}$ Myr) to achieve one-way communication (two-way communication). In this case, human beings need to survive $50_{-49.6}^{+250}$ Myr to receive one signal from other CETIs. Our results may quantitatively explain why we have not detected any alien signals so far. The uncertainty of the results has been discussed in detail and would be alleviated with the further improvement of our astronomical observation ability in the future.

We introduce a new method for detecting ultra-diffuse galaxies by searching for over-densities in intergalactic globular cluster populations. Our approach is based on an application of the log-Gaussian Cox process, which is a commonly used model in the spatial statistics literature but rarely used in astronomy. This method is applied to the globular cluster data obtained from the PIPER survey, a \textit{Hubble Space Telescope} imaging program targeting the Perseus cluster. We successfully detect all confirmed ultra-diffuse galaxies with known globular cluster populations in the survey. We also identify a potential galaxy that has no detected diffuse stellar content. Preliminary analysis shows that it is unlikely to be merely an accidental clump of globular clusters or other objects. If confirmed, this system would be the first of its kind. Simulations are used to assess how the physical parameters of the globular cluster systems within ultra-diffuse galaxies affect their detectability using our method. We quantify the correlation of the detection probability with the total number of globular clusters in the galaxy and the anti-correlation with increasing half-number radius of the globular cluster system. The S\'{e}rsic index of the globular cluster distribution has little impact on detectability.

The dust extinction curves toward individual sight lines in M33 are derived for the first time with a sample of reddened O-type and B-type supergiants obtained from the LGGS. The observed photometric data are obtained from the LGGS, PS1 Survey, UKIRT, PHATTER Survey, GALEX, Swift/UVOT and XMM-SUSS. We combine the intrinsic spectral energy distributions (SEDs) obtained from the ATLAS9 and Tlusty stellar model atmosphere extinguished by the model extinction curves from the silicate-graphite dust model to construct model SEDs. The extinction traces are distributed along the arms in M33, and the derived extinction curves cover a wide range of shapes ($R_V \approx 2-6$), indicating the complexity of the interstellar environment and the inhomogeneous distribution of interstellar dust in M33. The average extinction curve with $R_V \approx 3.39$ and dust size distribution $dn/da \sim a^{-3.45}{\rm exp}(-a/0.25)$ is similar to that of the MW but with a weaker 2175 Ang bump and a slightly steeper rise in the far-UV band. The extinction in the $V$ band of M33 is up to 2 mag, with a median value of $ A_V \approx 0.43$ mag. The multiband extinction values from the UV to IR bands are also predicted for M33, which will provide extinction corrections for future works. The method adopted in this work is also applied to other star-resolved galaxies (NGC 6822 and WLM), but only a few extinction curves can be derived because of the limited observations.

We present the first characterisation of the average dust attenuation curve at $z\sim1.3$ by combining rest-frame ultraviolet through near-IR photometry with Balmer decrement ($\mathrm{H}\alpha$/$\mathrm{H}\beta$) constraints for $\sim$900 galaxies with $8\lesssim\log (M_\star /M_\odot)<10.2$ at $0.75<z<1.5$ in the HST WFC3 IR Spectroscopic Parallel (WISP) and 3D-HST grism surveys. Using galaxies in SDSS, we establish that the ($\mathrm{H}\alpha$+[NII])/[OIII] line ratio and stellar mass are good proxies for the Balmer decrement in low-spectral resolution grism data when only upper-limits on $\mathrm{H}\beta$ are available and/or $\mathrm{H}\alpha$ is blended with [NII]. The slope of the $z\sim1.3$ attenuation curve ($A(0.15\mu m)/A(V)=3.15$) and its normalization ($R_V=3.26$) lie in-between the values found for $z=0$ and $z\sim2$ dust attenuation curves derived with similar methods. These provide supporting evidence that the average dust attenuation curve of star forming galaxies evolves continuously with redshift. The $z\sim1.3$ curve has a mild 2175\r{A} feature (bump amplitude, $E_b=0.83$; $\sim$25% that of the MW extinction curve), which is comparable to several other studies at $0<z\lesssim3$, and suggests that the average strength of this feature may not evolve significantly with redshift. The methods we develop to constrain dust attenuation from HST grism data can be applied to future grism surveys with JWST, Euclid, and RST. These new facilities will detect millions of emission line galaxies and offer the opportunity to significantly improve our understanding of how and why dust attenuation curves evolve.

Neutron stars (NSs) could efficiently capture dark matter (DM) due to their extreme densities and are considered sensitive probes of the presence and the properties of DM. The distribution of the DM in DM-admixed NSs (DANSs) is supposed to be either a dense dark core or an extended dark halo, which is subject to the DM fraction of DANS ($f_{\chi}$) and the DM properties, such as the mass ($m_{\chi}$) and the strength of the self-interaction ($y$). In this paper, we perform an in-depth analysis of the formation criterion for dark core/dark halo and point out that the relative distribution of these two components is essentially determined by the ratio of the central enthalpy of the DM component to that of the baryonic matter component inside DANSs. For the critical case where the radii of DM and baryonic matter are the same, we further derive an analytical formula to describe the dependence of $f^{\rm crit}_{\chi}$ on $m_{\chi}$ and $y$ for given DANS mass. The relative distribution of the two components in DANSs can lead to different observational effects on NSs. We here focus on the modification of the pulsar pulse profile due to the extra light-bending effect in the case of a dark-halo existence and conduct the first investigation of the dark-halo effects on NS pulse profiles. We find that the peak flux deviation is strongly dependent on the ratio of the halo mass to the radius of the DM component. Lastly, we perform Bayesian parameter estimation on the DM particle properties based on the recent X-ray observations of PSR J0030+0451 and PSR J0740+6620 by the Neutron Star Interior Composition Explorer.

Prestellar cores are generally spheroidal, some of which appear oblate while others appear prolate. Very few of them appear circular in projection. Little, however, is understood about the processes or the physical conditions under which prolate/oblate cores form. We find that an initially sub-critical filament experiencing relatively low pressure ($\lesssim 10^{4}$ K cm$^{-3}$) forms prolate cores (i.e., those with axial ratios in excess of unity) via gradual accumulation of gas in density crests. Meanwhile, a filament that is initially transcritical and experiences pressure similar to that in the Solar neighbourhood (between $\mathrm{few}\ \times 10^{4}$ K cm$^{-3}$ - $\mathrm{few}\ \times 10^{5}$ K cm$^{-3}$) forms oblate cores (i.e., those with axial ratios less than unity) via \emph{Jeans like} fragmentation. At higher pressure, however, fragments within the filament do not tend to survive as they rebound soon after formation. We also argue that quasi-oscillatory features of velocity gradient observed along the filament axis, and in the direction orthogonal to the axis, are integral to the filament evolution process and arise due to the growth of corrugations on its surface. The axial component of the velocity gradient, in particular, traces the gas-flow along the filament length. We therefore posit that it could be used to constrain the filament-formation mechanism. The magnitude of the respective components of velocity gradients increases with increasing external pressure.

In this paper I investigate the possibility to test Einstein's equations with observations of cosmological large scale structure. I first show that we have not tested the equations in observations concerning only the homogeneous and isotropic Universe. I then show with several examples how we can do better when considering the fluctuations of both, the energy momentum tensor and the metric. This is illustrated with galaxy number counts, intensity mapping and cosmic shear, three examples that are by no means exhaustive.

Large-scale Extreme-ultraviolet (EUV) waves are frequently observed as an accompanying phenomenon of flares and coronal mass ejections (CMEs). Previous studies mainly focus on EUV waves with single wavefronts that are generally thought to be driven by the lateral expansion of CMEs. Using high spatio-temporal resolution multi-angle imaging observations taken by the Solar Dynamic Observatory and the Solar Terrestrial Relations Observatory, we present the observation of a broad quasi-periodic fast propagating (QFP) wave train composed of multiple wavefronts along the solar surface during the rising phase of a GOES M3.5 flare on 2011 February 24. The wave train transmitted through a lunate coronal hole (CH) with a speed of 840 +/-67 km/s, and the wavefronts showed an intriguing refraction effect when they passed through the boundaries of the CH. Due to the lunate shape of the CH, the transmitted wavefronts from the north and south arms of the CH started to approach each other and finally collided, leading to the significant intensity enhancement at the collision site. This enhancement might hint the occurrence of interference between the two transmitted wave trains. The estimated magnetosonic Mach number of the wave train is about 1.13, which indicates that the observed wave train was a weak shock. Period analysis reveals that the period of wave train was $\sim$90 seconds, in good agreement with that of the accompanying flare. Based on our analysis results, we conclude that the broad QFP wave train was a large-amplitude fast-mode magnetosonic wave or a weak shock driven by some non-linear energy release processes in the accompanying flare.

We report the discovery and analysis of a triple-lens single-source (3L1S) microlensing event, OGLE-2019-BLG-1470. This event was first classified as a normal binary-lens single-source (2L1S) event, but a careful 2L1S modelling showed that it needs an additional lens or source to fit the observed data. It is found that the 3L1S model provides the best fit. The binary-lens binary-source (2L2S) model is excluded by $\Delta\chi^2 = 47$ and is also strong disfavored by its unreasonably small lens-source relative proper motion $\mu_{rel} \sim 0.8~{mas,yr^{-1}}$. We find that four 3L1S solutions can fit the observed data, and all of them contain a planet in a binary system. A Bayesian analysis based on a Galactic model indicates that the planet is super-Jovian and the binary stars are likely two M or K dwarfs. The projected primary-planet separation is about 3 AU. By investigating the properties of all microlensing planets in binary systems, we find another "missing planetary caustics" problem in the KMTNet planetary simple. A systematic KMTNet planetary anomaly search for planets in binary systems is needed.

We present results from a combined radio polarization and emission line study of five type 2 quasars at $z<0.2$ with the Karl G. Jansky Very Large Array (VLA) B-array at 5 GHz and Hubble Space Telescope (HST) [O~{\sc{iii}}] observations. These five sources are known to exhibit close association between radio structures and ionized gas morphology and kinematics. Four sources (J0945+1737, J1000+1242, J1356+1026 and J1430+1339) show polarization in the current data. J1010+1413 is the unpolarized source in our sample. We detect $0.5-1\%$ fractional polarization in the radio cores and a high fractional polarization ($10-30\%$) in the lobes of these sources. The morphological, spectral and polarization properties suggest a jet origin for radio emission in J0945+1737, J1000+1242, J1010+1413 and J1430+1339 whereas the current data cannot fully discern the origin of radio emission (jet or wind) in J1356+1026. An anti-correlation between various polarized knots in the radio and [O~{\sc{iii}}] emission is observed in our sources, similar to that observed in some radio-loud AGN in the literature. This suggests that the radio emission is likely to be depolarized by the emission-line gas. By modeling the depolarization effects, we estimate the size of the emission-line gas clouds to be $\sim(2.8\pm1.7)\times10^{-5}$ parsec and the amount of thermal material mixed with the synchrotron plasma to be $\sim(9.2\pm0.8)\times10^{5}$~M$_\odot$ in the lobe of J0945+1737 (which exhibits the most prominent polarization signature in its lobe). The current work demonstrates that the interplay of jets/winds and emission-line gas is most likely responsible for the nature of radio outflows in radio-quiet AGN.

Theoretically, misalignment between the magnetic field and rotational axis in a dense core is considered to be dynamically important in the star formation process, however, extent of this influence remains observationally unclear. For a sample of 32 Class 0 and I protostars in the Perseus Molecular Cloud, we analyzed gas motions using C$^{18}$O data from the SMA MASSES survey and the magnetic field structures using 850 $\mu$m polarimetric data from the JCMT BISTRO-1 survey and archive. We do not find any significant correlation between the velocity gradients in the C$^{18}$O emission in the protostellar envelopes at a 1,000 au scale and the misalignment between the outflows and magnetic field orientations in the dense cores at a 4,000 au scale, and there is also no correlation between the velocity gradients and the angular dispersions of the magnetic fields. However, a significant dependence on the misalignment angles emerges after we normalize the rotational motion by the infalling motion, where the ratios increase from $\lesssim1$ to $\gtrsim1$ with increasing misalignment angles. This suggests that the misalignment could prompt angular momentum transportation to the envelope scale but is not a dominant factor in determining the envelope rotation, and other parameters, like mass accretion in protostellar sources, also play an important role. These results remain valid after taking into account projection effects. The comparison between our estimated angular momentum in the protostellar envelopes and the sizes of the known protostellar disks suggests that significant angular momentum is likely lost between radii of $\sim$1,000-100 au in protostellar envelopes.

The advanced gravitational wave (GW) detector network has started {routine detection of } signals from merging compact binaries. Data indicate that in a fair fraction of these sources, at least one component was a neutron star, bringing with it the possibility of electromagnetic (EM) radiation. So far, a confirmed link between EM and GW radiation has been established for only one source, GW170817. Joint analysis of broadband multiwavelength data and the GW signal have yielded rich information spanning fields as varied as jet physics, cosmology, and nucleosynthesis. Here, we discuss the importance of such joint observations, as well as current and near-future efforts to discover and study more EM counterparts to GW sources.

Hot, massive (OB) stars experience strong line-driven stellar winds and mass loss. As the majority of efficient driving lines are metallic, the amount of wind driving and mass loss is dependent on the stellar metallicity Z. In addition, line-driven winds are intrinsically inhomogeneous and clumpy. However, to date, neither theoretical nor empirical studies of line-driven winds have investigated how such wind clumping may also depend on Z. We theoretically investigated the degree of wind clumping due to the line-deshadowing instability (LDI) as a function of Z. We performed two-dimensional hydrodynamic simulations of the LDI with an assumed one-dimensional radiation line force for a grid of O-star wind models with fixed luminosity, but with different metal contents by varying the accumulative line strength Qbar describing the total ensemble of driving lines. We find that, for this fixed luminosity, the amount of wind clumping decreases with metallicity. The decrease is clearly seen in the statistical properties of our simulations, but is nonetheless rather weak; a simple power-law fit for the dependence of the clumping factor f_cl = <rho^2>/<rho>^2 on metallicity yields f_cl ~ Z^(0.15 +/- 0.01). This implies that empirically derived power-law dependencies of mass-loss rate Mdot on metallicity -- which were previously inferred from spectral diagnostics effectively depending on Mdot*sqrt(f_cl) but without having any constraints on f_cl(Z) -- should be only modestly altered by clumping. We expect that this prediction can be directly tested using new data from the Hubble Space Telescope Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) project.

The galaxy cluster SRGe CL2305.2$-$2248 (SPT-CL J2305$-$2248, ACT-CL J2305.1$-$2248) is one of the most massive clusters at high redshifts ($z \simeq 0.76$) and is of great interest for cosmology. For an optical identification of this cluster, deep images were obtained with the 1.5-m Russian-Turkish telescope RTT-150. Together with the open archival data of the Hubble Space Telescope, it became possible to identify candidates for gravitationally lensed images of distant blue galaxies in the form of arcs and arclets. The observed giant arc near the brightest cluster galaxies allowed us to estimate the radius of the Einstein ring, which is $ 9.8 \pm 1.3 $ arcseconds. The photometric redshift of the lensed source was obtained ($ z_s = 2.44 \pm 0.07 $). Its use in combination with the Einstein radius estimate made it possible to independently estimate the \cl2305 mass. It was done by extrapolating the strong lensing results to large radii and using the model density distribution profiles in relaxed clusters. This extrapolation leads to mass estimates $ \sim 1.5-3 $ times smaller than those obtained from X-ray and microwave observations. A probable cause for this discrepancy may be the process of cluster merging, which is also confirmed by SRGe CL2305.2-2248 morphology in the optical range.

We report the discovery of a highly eccentric long-period Jovian planet orbiting the hot-Jupiter host HD\,83443. By combining radial velocity data from four instruments (AAT/UCLES, Keck/HIRES, HARPS, Minerva-Australis) spanning more than two decades, we find evidence for a planet with m~sin~$i=1.35^{+0.07}_{-0.06}$\,\mj, moving on an orbit with $a=8.0\pm$0.8\,au and eccentricity $e=0.76\pm$0.05. We combine our radial velocity analysis with \textit{Gaia} eDR3 /\textit{Hipparcos} proper motion anomalies and derive a dynamical mass of $1.5^{+0.5}_{-0.2} M_{\rm Jup}$. We perform a detailed dynamical simulation that reveals locations of stability within the system that may harbor additional planets, including stable regions within the habitable zone of the host star. HD\,83443 is a rare example of a system hosting a hot Jupiter and an exterior planetary companion. The high eccentricity of HD\,83443c suggests that a scattering event may have sent the hot Jupiter to its close orbit while leaving the outer planet on a wide and eccentric path.

In the last decade, white-light illuminated Fabry-P\'erot interferometers wave been established as a widely used, relatively simple, reliable, and cost-effective way to precisely calibrate high-resolution echelle spectrographs. However, Terrien et al. (2021) recently reported a chromatic drift of the Fabry-P\'erot interferometer installed at the Habitable-zone Planet Finder spectrograph. In particular, they found that the variation of the etalon effective gap size is not achromatic as usually assumed but in fact depends on wavelength. Here, we present a similar study of the Espresso Fabry-P\'erot interferometer. Using daily calibrations spanning a period of over 2.5 years, we also find clear evidence for a chromatic drift with an amplitude of a few cm/s per day that has a characteristic, quasi-oscillatory dependence on wavelength. We conclude that this effect is probably caused by an aging of the dielectric mirror coatings and expect that similar chromatic drifts might affect all Fabry-P\'erot interferometers used for calibration of astronomical spectrographs. However, we also demonstrate that the chromatic drift can be measured and in principle corrected using only standard calibrations based on hollow cathode lamp spectra.

Microwave Kinetic Inductance Detector (MKID) arrays are currently being developed and deployed for astronomical applications in the visible and near infrared and for sub-millimetre astronomy. One of the main drawbacks of MKIDs is that large arrays would exhibit a pixel yield, the percentage of individually distinguishable pixels to the total number of pixels, of 75 - 80 %. Imperfections arising during the fabrication can induce an uncontrolled shift in the resonance frequency of individual resonators which can end up resonating at the same frequency of a different resonator. This makes a number of resonators indistinguishable and therefore unusable for imaging. This paper proposes an approach to individually re-tune the colliding resonators in order to remove the degeneracy and increase the number of MKIDs with unique resonant frequencies. The frequency re-tuning is achieved through a DC bias of the resonator, the kinetic inductance of a superconducting thin film is current dependent and its dependence is non linear. Even though this approach has been already proposed, an innovative pixel design, described in this paper, may solve two issues previously described in literature such as increased electromagnetic losses to the DC-bias line, and the multiplexibility of multiple resonators on a single feedline.

We present deep, full-sky maps built from Wide-field Infrared Survey Explorer (WISE) and NEOWISE exposures spanning the 2010 January - 2020 December time period. These coadds, which incorporate roughly 8 years of W1 (3.4 microns) and W2 (4.6 microns) imaging, are the deepest ever full-sky maps at wavelengths of 3-5 microns. Photometry based on these coadds will be a component of DESI Legacy Imaging Surveys DR10.

Being able to distinguish between galaxies that have recently undergone major merger events, or are experiencing intense star formation, is crucial for making progress in our understanding of the formation and evolution of galaxies. As such, we have developed a machine learning framework based on a convolutional neural network (CNN) to separate star forming galaxies from post-mergers using a dataset of 160,000 simulated images from IllustrisTNG100 that resemble observed deep imaging of galaxies with Hubble. We improve upon previous methods of machine learning with imaging by developing a new approach to deal with the complexities of contamination from neighbouring sources in crowded fields and define a quality control limit based on overlapping sources and background flux. Our pipeline successfully separates post-mergers from star forming galaxies in IllustrisTNG $80\%$ of the time, which is an improvement by at least 25\% in comparison to a classification using the asymmetry ($A$) of the galaxy. Compared with measured S\'ersic profiles, we show that star forming galaxies in the CANDELS fields are predominantly disc-dominated systems while post-mergers show distributions of transitioning discs to bulge-dominated galaxies. With these new measurements, we trace the rate of post-mergers among asymmetric galaxies in the universe finding an increase from $20\%$ at $z=0.5$ to $50\%$ at $z=2$. Additionally, we do not find strong evidence that the scattering above the Star Forming Main Sequence (SFMS) can be attributed to major post-mergers. Finally, we use our new approach to update our previous measurements of galaxy merger rates $\mathcal{R} = 0.022 \pm 0.006 \times (1+z)^{2.71\pm0.31}$

It is recently proposed that cosmic rays generate a seed magnetic field in the early universe. In this paper, we propose another generation mechanism of magnetic fields by cosmic rays, which is the Biermann battery driven by resistive heating induced by the streaming of cosmic rays. This new mechanism is dominant in small-scale, low-temperature, and strongly-ionized regions, compared with other previously proposed mechanisms. Because cosmic rays are expected to be accelerated after the death of the first stars, this mechanism can work during structure formation in the early universe. We show that it makes the seed magnetic field with sufficient strength for the subsequent dynamo to amplify it to the micro Gauss level in the current galaxies.

The discovery and characterization of extrasolar planets using radial velocity (RV) measurements is limited by noise sources from the surfaces of host stars. Current techniques to suppress stellar magnetic activity rely on decorrelation using an activity indicator (e.g., strength of the Ca II lines, width of the cross-correlation function, broadband photometry) or measurement of the RVs using only a subset of spectral lines that have been shown to be insensitive to activity. Here, we combine the above techniques by constructing a high signal-to-noise activity indicator, the depth metric $\mathcal{D}(t)$, from the most activity-sensitive spectral lines using the "line-by-line" method of Dumusque (2018). Analogous to photometric decorrelation of RVs or Gaussian progress regression modeling of activity indices, time series modeling of $\mathcal{D}(t)$ reduces the amplitude of magnetic activity in RV measurements; in an $\alpha$CenB RV time series from HARPS, the RV RMS was reduced from 2.67 to 1.02 m s$^{-1}$. $\mathcal{D}(t)$ modeling enabled us to characterize injected planetary signals as small as 1 m s$^{-1}$. In terms of noise reduction and injected signal recovery, $\mathcal{D}(t)$ modeling outperforms activity mitigation via the selection of activity-insensitive spectral lines. For Sun-like stars with activity signals on the m s$^{-1}$ level, the depth metric independently tracks rotationally modulated and multiyear stellar activity with a level of quality similar to that of the FWHM of the CCF and log$R^{\prime}_{HK}$. The depth metric and its elaborations will be a powerful tool in the mitigation of stellar magnetic activity, particularly as a means of connecting stellar activity to physical processes within host stars.

We present the results of a radio observing campaign on GRB 201216C, combined with publicly available optical and X-ray data. The detection of very high energy (VHE, >100GeV) emission by MAGIC makes this the fifth VHE GRB at time of publication. Comparison between the optical and X-ray light curves show that GRB 201216C is a dark GRB, i.e. the optical emission is significantly absorbed and is fainter than expected from the X-ray detections. Our e-MERLIN data also shows evidence of diffractive interstellar scintillation. We can study the column density along the line-of-sight to the GRB in both the host galaxy, from the damped optical light curve, and the Milky Way, via scintillation studies. We find that the afterglow is best modelled using a jet-cocoon geometry within a stellar wind environment. Fitting the data with a multi-component model we estimate that the optical, X-ray and higher-frequency radio data before ~25days originates from an ultra-relativistic jet with an isotropic equivalent kinetic energy of (0.6-10)x10^52erg and an opening angle of ~1-9deg. The lower-frequency radio emission detected by MeerKAT, from day 28 onwards, is produced by the cocoon with a kinetic energy that is between two and seven orders of magnitude lower (0.02-50)x10^48erg. The energies of the two components are comparable to those derived in simulations of such scenarios.

A growing disquiet has emerged in recent years that standard stellar models are at odds with observations of the colour-magnitude diagrams (CMDs) and lithium depletion patterns of pre main sequence (PMS) stars in clusters. In this work we select 1,246 high probability K/M-type constituent members of 5 young open clusters (5--125\,Myr) in the Gaia-ESO Survey to test a series of models that use standard input physics and others that incorporate surface magnetic fields or cool starspots. We find that: standard models provide systematically under-luminous isochrones for low-mass stars in the CMD and fail to predict Li-depletion of the right strength at the right colour; magnetic models provide better CMD fits with isochrones that are $\sim 1.5-2$ times older, and provide better matches to Li depletion patterns. We investigate how rotation periods, most of which are determined here for the first time from Transiting Exoplanet Survey Satellite data, correlate with CMD position and Li. Among the K-stars in the older clusters we find the brightest and least Li-depleted are the fastest rotators, demonstrating the classic "Li-rotation connection" for the first time at $\sim 35$ Myr in NGC 2547, and finding some evidence that it exists in the early M-stars of NGC 2264 at $<10\,$Myr. However, the wide dispersion in Li depletion observed in fully-convective M-dwarfs in the $\gamma$ Vel cluster at $\sim 20$ Myr appears not to be correlated with rotation and is challenging to explain without a very large ($>10$ Myr) age spread.

We analyze the energy dependence of the X-ray pulse profile and the phase-resolved spectra (PRS) of the Crab pulsar using observations from the Neutron star Interior Composition Explorer (NICER) and the Hard X-ray Modulation Telescope (Insight-HXMT). We parameterize the pulse profiles and quantify the evolution of these parameters in the broad energy band of 0.4-250 keV. A log-parabola function is used to fit the PRS in 2-250 keV, and the curvature of the spectrum, i.e., the evolution of the photon index with energy, as represented by the parameter \{beta} of the log-parabola model, also changes with phase. The relation of \{beta} and phase has two turning points slightly later than those of the pulse intensity profile, where the values of \{beta} are the lowest, suggesting that the energy-loss rate of the particles is the lowest in the corresponding regions. A three-segment broken-power-law model is also used to fit those PRS. The differences between the hard spectral index and the soft ones have a distribution similar to that of \{beta}, confirming the fitting results of the log-parabola model, while the broken energies are generally higher in the region bridging the two pulses. We find anticorrelations between the spectral indices and the curvature of the log-parabola model fitting and a similar anticorrelation between the spectral indices and broken energies of the broken-power-law model fitting, suggesting a scenario where the highest-energy particles are produced in regions where radiation energy loss is strongest.

We present the first data release of HI sources extracted from a pilot extragalactic HI survey using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). We extracted sources from three-dimensional(3D) spectral data cubes to perform interactive searching and computing, yielding global HI parameters for eachsource, extending redshift ranges of HI emission up to z = 0.04.A total of 544 extragalactic HI sources have been detected by the pilot FAST HI drift scan survey covering part of the sky region in right ascension(R.A. or $\alpha$) and declination(Dec or $\delta$) range $00^{\rm h} 47^{\rm m}< \rm R.A.(J2000)<23^{\rm h}22^{\rm m}$ and $+24^{\circ}<\rm Dec.(J2000)<+43^{\circ}$ . Of which, 528 sources are matched with optical counterparts via examination of digital optical survey databases collected from NED (this http URL) and Vizier (https://vizier.u-strasbg.fr/viz-bin/VizieR-2) data center, and 449 of them have optical velocities. Furthermore, We detect 36 galaxies with HI mass $ < 10^8 M_{\odot}$, which is significant for the study of low-mass systems in local universe. We present catalogs for all HI detections with signal to noise ratio(S/N) greater than 5.1. The data are classified into four categories based on their S/N and baseline qualities, which are flagged with code 1 to 4 :(1) 422 sources with signal of S/N \textgreater 6.5; (2) 61 sources with signal of $\rm 5.1\lesssim S/N\lesssim 6.5$; (3) 28 sources with relatively poor baselines; (4) 33 sources that are partly masked by strong RFIs. Besides, we find 16 HI sources that have not been matched with any counterparts in the existing galaxy catalogs. This data release can provide guidence for the future extragalactic HI survey with FAST.

Polarization measurements of the gamma-ray component of transient sources are of great scientific interest, they are however, also highly challenging. This is due to the typical low signal to noise and the potential for significant systematic errors. Both issues are made worse by the transient nature of the events which prompt one to observe a large portion of the sky. The POLAR instrument was designed as a dedicated transient gamma-ray polarimeter. It made use of a large effective area and large field of view to maximize the signal to noise as well as the number of observed transients. Additionally, it was calibrated carefully on ground and in orbit to mitigate systematic errors. The main scientific goal of POLAR was to measure the polarization of the prompt emission of Gamma-Ray Bursts. During the 6 months operation in orbit POLAR observed 55 Gamma-Ray Bursts of which 14 were bright enough to allow for constraining polarization measurements. In this chapter we mainly discuss about the POLAR instrument along with the calibration and analysis procedures. Two analyses are described, the first is a straightforward method previously implemented in polarization measurements, whilst the second was developed to improve the sensitivity and to mitigate several of the issues with the former. Both methods are described in detail along with information on how these can be extended to perform time and energy resolved polarization measurements.

We discovered rapid intra-day variability in radio source PMN J1726+0639 at GHz frequencies, during a survey to search for such variability with the Australia Telescope Compact Array. Follow-up observations were conducted over two years and revealed a clear, repeating annual cycle in the rate, or characteristic timescale, of variability, showing that the observed variations can be attributed to scintillations from interstellar plasma inhomogeneities. The strong annual cycle includes an apparent "standstill" in April and another in September. We fit kinematic models to the data, allowing for finite anisotropy in the scintillation pattern. The cycle implies a very high degree of anisotropy, with an axial ratio of at least 13:1, and the fit is consistent with a purely one-dimensional scintillation pattern. The position angle of the anisotropy, and the transverse velocity component are tightly constrained. The parameters are inconsistent with expectations from a previously proposed model of scattering associated with plasma filaments radially oriented around hot stars. We note that evidence for a foreground interstellar cloud causing anomalous Ca II absorption towards the nearby star Rasalhague ($\alpha$ Oph) has been previously reported, and we speculate that the interstellar scintillation of PMN 1726+0639 might be associated with this nearby cloud.

Most simulations of outflow feedback on star formation are based on the assumption that outflows are driven by a wide angle "X-wind," rather than a narrow jet. However, the arguments initially raised against pure jet-driven flows were based on steady ejection in a uniform medium, a notion that is no longer supported based on recent observations. We aim to determine whether a pulsed narrow jet launched in a density-stratified, self-gravitating core could reproduce typical molecular outflow properties, without the help of a wide-angle wind component. We performed axisymmetric hydrodynamic simulations using the MPI-AMRVAC code with optically thin radiative cooling on timescales up to 10000 yrs. Then we computed and compared the predicted properties with observational data. First, the jet-driven shell expands faster and wider through a core with steeply decreasing density than through an uniform core. Second, when blown into the same singular flattened core, a jet-driven shell has a similar width as a wide-angle wind-driven shell in the first few hundred years, but a decelerating expansion on long timescales. The flow adopts a conical shape and a base opening angle reaching up to $90\unicode{xb0}$. Third, after $\sim$ 10000 yrs, a pulsed jet-driven shell shows fitting features and a qualitative resemblance with recent observations of protostellar outflows with the Atacama Large Millimeter Array (ALMA), such as HH46-47 and CARMA-7. In particular, similarities are seen in the shell widths, opening angles, position-velocity diagrams, and mass-velocity distribution, with some showing a closer resemblance than in simulations based on a wide-angle "X-wind" model. Therefore, a realistic ambient density stratification in addition to millenia-long integration times are equally essential to reliably predict the properties of outflows driven by a pulsed jet and to confront them with the observations.

Phase curves of asteroids are typically considered to depend solely on the scattering properties of airless particulate surfaces and the size of the object being studied. In this study, we demonstrate the additional dependence of phase curves on object shape, rotation pole orientation, and viewing geometry over an apparition. Variations in the phase curve of near-Earth asteroid (159402) 1999 AP10 over its apparition from July 2020 - January 2021 are verified to be due to aspect changes over the apparition. This is achieved through shape modelling of the asteroid and simulation of the phase curve over the apparition. We present simulations of asteroid phase curves over a range of geometries to understand the potential magnitude of this aspect effect, and under which circumstances it can begin to dominate in the phase curves. This dependence on aspect may introduce significant additional uncertainty in the properties derived from phase curve data. We provide and demonstrate software code to estimate the aspect-related uncertainty in near-Earth asteroid phase curves through simulation and model fitting of a randomly generated sample of ellipsoidal asteroid models over the observed viewing geometry. We demonstrate how ignoring this effect may lead to misleading interpretations of the data and underestimation of uncertainties in further studies, such as those in the infrared that use phase curve derived parameters when fitting physical properties of an asteroid.

RR Lyrae variable stars have long been reliable standard candles used to discern structure in the Local Group. With this in mind, we present a routine to identify groupings containing a statistically significant number of RR Lyrae variables in the Milky Way environment. RR Lyrae variable groupings, or substructures, with potential Galactic archaeology applications are found using a forest of agglomerative, hierarchical clustering trees, whose leaves are Milky Way RR Lyrae variables. Each grouping is validated by ensuring that the internal RR Lyrae variable proper motions are sufficiently correlated. Photometric information was collected from the Gaia second data release and proper motions from the (early) third data release. After applying this routine to the catalogue of 91234 variables, we are able to report sixteen unique RR Lyrae substructures with physical sizes of less than 1 kpc. Five of these substructures are in close proximity to Milky Way globular clusters with previously known tidal tails and/or a potential connection to Galactic merger events. One candidate substructure is in the neighbourhood of the Large Magellanic Cloud but is more distant (and older) than known satellites of the dwarf galaxy. Our study ends with a discussion of ways in which future surveys could be applied to the discovery of Milky Way stellar streams.

The Simons Observatory (SO) is a suite of instruments sensitive to temperature and polarization of the cosmic microwave background (CMB) to be located at Cerro Toco in the Atacama Desert in Chile. Five telescopes, one large aperture telescope and four small aperture telescopes, will host roughly 70,000 highly multiplexed transition edge sensor (TES) detectors operated at 100 mK. Each SO focal plane module (UFM) couples 1,764 TESes to microwave resonators in a microwave multiplexing (uMux) readout circuit. Before detector integration, the 100 mK uMux components are packaged into multiplexing modules (UMMs), which are independently validated to ensure they meet SO performance specifications. Here we present the assembly developments of these UMM readout packages for mid frequency (90/150 GHz) and ultra high frequency (220/280 GHz) UFMs.

The SKA will be the largest radio astronomy observatory ever built, providing unprecedented sensitivity over a very broad frequency (50 MHz to 15.3 GHz). The SKA-Low (50 - 350 MHz), will be built at the MRO in Western Australia. It will consist of 512 stations each composed of 256 dual-polarised antennas, and the sensitivity of an individual station is pivotal to the performance of the entire SKA-Low telescope. The answer to the question in the title is, it depends. The sensitivity of a low frequency array, such as an SKA-Low station, depends strongly on the pointing direction of the digitally formed station beam and the local sidereal time (LST), and is different for the two orthogonal polarisations of the antennas. The accurate prediction of the SKA-Low sensitivity in an arbitrary direction in the sky is crucial for future observation planning. We present here a sensitivity calculator for the SKA-Low radio telescope, using a database of pre-computed sensitivity values for two realisations of an SKA-Low station architecture. One realisation uses the log-periodic antennas selected for SKA-Low. The second uses a known benchmark, in the form of the bowtie dipoles of the MWA. Data collected by both stations (deployed at the MRO in 2019) were used to measure their sensitivity at selected frequencies and over at least 24 h intervals, and were compared to the predictions described in this paper. The sensitivity values stored in the SQLite database were pre-computed for the X, Y and Stokes I polarisations in 10 MHz frequency steps, 0.5 hour LST intervals, and 5 degree resolution in pointing directions. The database allows users to estimate the sensitivity of SKA-Low for their favourite object using interactive web-based or command line interface, which can also calculate the sensitivity for arbitrary pointing directions, frequencies, and times without interpolations.

3C186 is a powerful radio loud quasar (QSO) at the center of a cool-core cluster at z=1.06. Previous studies reported evidence for a projected spatial offset of ~1'' between the isophotal center of the galaxy and the point-source QSO as well as a spectral shift of ~2000 km/s between the narrow and broad line region of the system. In this work we report high-resolution molecular gas CO(4-3) observations of the system taken with NOEMA interferometer. We clearly detect a large reservoir of molecular gas, $M_{H_2}\sim8\times10^{10}~M_\odot$, that is cospatial with the host galaxy and likely associated with a rotating disk-like structure. We firmly confirm both the spatial offset of the galaxy's gas reservoir with respect to the continuum emission of the QSO and the spectral offset with respect to the redshift of the broad line region. Our morphological and kinematical analysis confirms that the most likely scenario to explain the 3C186 system is that the QSO is a kicked super-massive black hole (SMBH), which we believe may have resulted from a strong gravitational wave recoil as two SMBHs coalesced after the merger of their host galaxies.

We present the capabilities of Galapagos--2 and Galfitm in the context of fitting 2-component profiles to galaxies, on the way to providing complete multi-band, multi-component fitting of large samples of galaxies in future surveys. We release both the code and the fit results to 234,239 objects from the DR3 of the Gama survey, a sample significantly deeper than previous works. We use stringent tests on both simulated and real data, as well as comparison to public catalogues to evaluate the advantages of using multi-band over single-band data. We show that multi-band fitting using Galfitm provides significant advantages when trying to decompose galaxies into their individual constituents, as more data are being used, by effectively being able to use the colour information buried in the individual exposures to its advantage. Using simulated data, we find that multi-band fitting significantly reduces the deviations from real parameter values, allows component sizes and S\'ersic indices to be recovered more accurately, and, by design, constrains the band-to-band variations of these parameters to more physical values. On both simulated and real data, we confirm that the SEDs of the 2 main components can be recovered to fainter magnitudes compared to using single-band fitting, which tends to recover disks and bulges to - on average - have identical SEDs when the galaxies become too faint, instead of the different SEDs they truly have. By comparing our results to those provided by other fitting codes, we confirm that they agree in general, but measurement errors can be significantly reduced by using the multi-band tools developed by the MegaMorph project. We conclude that the multi-band fitting employed by Galapagos-2 and Galfitm significantly improves the accuracy of structural galaxy parameters and enables much larger samples to be be used in a scientific analysis.

Solar flares create adverse space weather impacting space and Earth-based technologies. However, the difficulty of forecasting flares, and by extension severe space weather, is accentuated by the lack of any unique flare trigger or a single physical pathway. Studies indicate that multiple physical properties contribute to active region flare potential, compounding the challenge. Recent developments in Machine Learning (ML) have enabled analysis of higher dimensional data leading to increasingly better flare forecasting techniques. However, consensus on high-performing flare predictors remains elusive. In the most comprehensive study till date, we conduct a comparative analysis of four popular ML techniques (K-Nearest Neighbor, Logistic Regression, Random Forest Classifier, and Support Vector Machine) by training these on magnetic parameters obtained from the Helioseismic Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) during the entirety of solar cycle 24. We demonstrate that Logistic Regression and Support Vector Machine algorithms perform extremely well in forecasting active region flaring potential. The logistic regression algorithm returns the highest true skill score of $0.967 \pm 0.018$, possibly the highest classification performance achieved with any parametric study alone. From a comparative assessment, we establish that the magnetic properties like total current helicity, total vertical current density, total unsigned flux, R\_value, and total absolute twist are the top-performing flare indicators. We also introduce and analyze two new performance metrics, namely, Severe and Clear Space Weather indicators. Our analysis constrains the most successful ML algorithms and identifies physical parameters that contribute most to active region flare productivity.

Non-observation of Faraday rotation of polarized radio emission from extragalactic sources can be used to constrain volume-filling intergalactic magnetic field (IGMF) of cosmological origin. Previously derived Faraday rotation constraints on IGMF have used analytic models that made a range of simplifying assumptions about magnetic field evolution in the intergalactic medium and did not consider the effect of baryonic feedback on large-scale structures. We revise the Faraday rotation constraint on IGMF using a numerical model of the intergalactic medium from IllustrisTNG cosmological simulation that includes a sophisticated model of the baryonic feedback. We use the IllustrisTNG model to calculate the rotation measure and compare the resulting mean and median of the absolute value of the rotation measure with the data of the NRAO VLA Sky Survey (NVSS). The numerical model of the intergalactic medium includes the full magneto-hydrodynamic model of the compressed primordial magnetic field as well as the model of the regions where the magnetic field is not primordial, but it is rather produced by the process of the baryonic feedback. Separating the two types of regions, we are able to assess the primordial magnetic field influence on the Faraday rotation signal. We find that correction of the model of compressed primordial field and account for the fact that part of the intergalactic medium is occupied by magnetic fields spread by the baryonic feedback process rather than by the primordial field relaxed the Faraday rotation bound by a factor of $\simeq 3$, to $B_0< 1.8\times10^{-9}$ G for large correlation length IGMF.

Gravitationally lensed supernovae (LSNe) are important probes of cosmic expansion, but they remain rare and difficult to find. Current cosmic surveys likely contain and 5-10 LSNe in total while next-generation experiments are expected to contain several hundreds to a few thousands of these systems. We search for these systems in observed Dark Energy Survey (DES) 5-year SN fields -- 10 3-sq. deg. regions of sky imaged in the $griz$ bands approximately every six nights over five years. To perform the search, we utilize the DeepZipper approach: a multi-branch deep learning architecture trained on image-level simulations of LSNe that simultaneously learns spatial and temporal relationships from time series of images. We find that our method obtains a LSN recall of 61.13% and a false positive rate of 0.02% on the DES SN field data. DeepZipper selected 2,245 candidates from a magnitude-limited ($m_i$ $<$ 22.5) catalog of 3,459,186 systems. We employ human visual inspection to review systems selected by the network and find three candidate LSNe in the DES SN fields.

At the first Galactic quadrant, at l=33.134, b=-0.091, an extended photodissociation region generated by an HII region complex lies. This region is related to abundant molecular gas, and particularly, a hot molecular core, known as G33.133-mm3, appears embedded in a molecular clump. Using data from the James Clerk Maxwell Telescope with an angular resolution of about 15", we studied the 13CO/C18O abundance ratio towards the mentioned molecular clump and its relation with the ultraviolet radiation. At smaller spatial scales, using data from the Atacama Large Millimeter Array (angular resolution about 0.7\arcsec), the hot molecular core G33.133-mm3, that has a size of about 2600 au, and is an appropriate site to form stars, was characterized. In particular, some points about its chemistry are mentioned based on the emission of the cyanide or nitrile radical (CN) and others more complex molecules, such as CH3OH, CH3CN, CH3OCHO, and CH3CCH.

The atmospheres of sub-Neptunes are expected to exhibit considerable chemical diversity, beyond what is anticipated for gas-giant exoplanets. In the current study, we construct self-consistent radiative transfer and equilibrium chemistry models to explore this chemical diversity. We use GJ 436 b as a case study to further study joint atmosphere-interior models. In particular, we constrain the properties of the interior and atmosphere of the planet based on the available Spitzer measurements. While it is possible to fit the emission spectrum of GJ 436 b using a high-metallicity model, we demonstrate that such an atmosphere is inconsistent with physically plausible interior structures. It remains the case that no existing study can adequately fit the 4.5-micron Spitzer secondary eclipse measurement, which is probably caused by chemical disequilibrium. Finally, an information content analysis reveals that emission and transmission spectra constrain the carbon-to-oxygen ratio and metallicity at different wavelengths, but the former are less susceptible to flat spectra stemming from highly metal-enriched atmospheres. With the recently-launched JWST, we recommend that future analysis of emission and transmission spectra of sub-Neptune planets are carried out self-consistently using both the atmospheric and interior structure models.

We analyze circular velocity profiles of seven ultra-diffuse galaxies (UDGs) that are isolated and gas-rich. Assuming that the dark matter halos of these UDGs have a modified Navarro-Frenk-White (NFW) density profile with a constant density core, the inferred halo concentrations are systematically lower than the cosmological median, even as low as $-0.6$ dex (about $5\sigma$ away) in some cases. Alternatively, similar fits can be obtained with a density profile that scales roughly as $1/r^2$ for radii larger than a few $\rm kpc$. Both solutions require the radius where the halo circular velocity peaks ($R_{\rm max}$) to be much larger than the median expectation. Surprisingly, we find an overabundance of such large $R_{\rm max}$ halos in the IllustrisTNG dark matter-only simulations compared to the Gaussian expectation. These halos form late and have higher spins compared to median halos of similar masses. The inner densities of the most extreme among these late-forming halos are higher than their NFW counterparts, leading to a $\sim 1/r^2$ density profile. However, the two well-resolved UDGs in our sample strongly prefer lower dark matter densities in the center than the simulated ones. Comparing to IllustrisTNG hydrodynamical simulations, we also find a tension in getting both low enough circular velocities and high enough halo mass to accommodate the measurements. Our results indicate that the gas-rich UDGs present a significant challenge for galaxy formation models.

We present DarkFlux, a software tool designed to analyze indirect-detection signatures for next-generation models of dark matter (DM) with multiple annihilation channels. Version 1.0 of this tool accepts user-generated models with $2\to 2$ tree-level dark matter annihilation to pairs of Standard Model (SM) particles and analyzes DM annihilation to $\gamma$ rays. The tool consists of three modules -- the annihilation fraction module, the flux module, and the analysis module -- which can be run in a loop in order to scan over DM mass if desired. [A description of each module is available in the full abstract.] DarkFlux v1.0 compares the total $\gamma$-ray flux to a joint-likelihood analysis of fifteen dwarf spheroidal galaxies (dSphs) analyzed by the $Fermi$-LAT collaboration. DarkFlux automatically provides data tables and can plot the output of the three modules. In this manual, we briefly motivate this indirect-detection computer tool and review the essential DM physics. We then describe the several modules of DarkFlux in greater detail. Finally, we show how to install and run DarkFlux and provide two worked examples demonstrating its capabilities.

Black holes in scalar-Gauss-Bonnet gravity are prone to scalarization, that is a spontaneous development of scalar hair for strong enough spacetime curvature while the weak field regime of the theory coincides with general relativity. Since large spacetime curvature is associated with smaller black hole masses, the merging of black holes can lead to dynamical descalarization. This is a spontaneous release of the scalar hair of the newly formed black hole in case its mass is above the scalarization threshold. Depending on the exact form of the Gauss-Bonnet coupling function, the stable scalarized solutions can be either continuously connected to the Schwarzschild black hole, or the transitions between the two can happen with a jump. By performing simulations of black hole head-on collisions in scalar-Gauss-Bonnet gravity prone to dynamical descalization, we have demonstrated that such a jump can be clearly observed in the accumulated gravitational wave data of multiple merger events with different masses. The distinct signature in the gravitational wave signal will share similarities with the effects expected from first order matter phase transitions happening during neutron star binary mergers.

Black holes typically inhabit highly dynamical galactic environments and are frequently permeated by accretion media. The inevitable scattering of scalar, electromagnetic and gravitational waves off rotating and charged black holes provides a remarkable demonstration of the energy extraction and subsequent amplification of scattered waves under the expense of the compact object's rotational and electromagnetic energy; a phenomenon known as superradiance. Certain circumstances tremendously favor the energy extraction process in such extent that linear superradiant instabilities are triggered. We examine the superradiant amplification of monochromatic charged scalar fields impinging Reissner-Nordstr\"om-de Sitter black holes which are known to exhibit superradiantly unstable quasinormal modes. We find that even though the frequency range of superradiance is reduced when a positive cosmological constant is incorporated, the amplification factors are significantly elevated with respect to those occurring in Reissner-Nordstr\"om spacetime. Intriguingly, we confirm that the long-lived quasinormal resonances that reside in the superradiant regime induce resonant peaks when the wave's frequency matches the real part of the quasinormal mode, regardless of the spacetime's modal stability.

We study cosmological perturbations for k-essence and kinetic gravity braiding models in the context of the two-field measure theory (TMT). Considering scalar perturbations and the uniform field gauge, we obtain the sound speed of the fields and present a stability analysis by means of the kinetic matrix and the mass eigenvalues. For k-essence models, in the two-field measure theory, the speed of propagation of the field is modified completely due to the new measure field and it gives rise to crucial differences with respect to the case without new measure. The stability analysis gives a physical viable model for the Universe. For the kinetic gravity braiding models in the two-field measure theory we get that, in general, the speed of perturbations is equal to the speed of light which is a consequence of the properties of the new measure field. In the later case, there is always a ghost field. Furthermore, we calculate general expressions for the mass eigenvalues and find, for an explicit example, the existence of tachyonic instabilities.

Linearized gravity in the Very Special Relativity (VSR) framework is considered. We prove that this theory allows for a non-zero graviton mass $m_g$ without breaking gauge invariance nor modifying the relativistic dispersion relation. We find the analytic solution for the new equations of motion in our gauge choice, verifying as expected the existence of only two physical degrees of freedom. Finally, through the geodesic deviation equation, we confront some results for classic gravitational waves (GW) with the VSR ones: we see that the ratios between VSR effects and classical ones are proportional to $(m_g/E)^2$, $E$ being the energy of a graviton in the GW. For GW detectable by the interferometers LIGO and VIRGO this ratio is at most $10^{-20}$. However, for GW in the lower frequency range of future detectors, like LISA, the ratio increases significantly to $ 10^{-10}$, that combined with the anisotropic nature of VSR phenomena may lead to observable effects.

Based on the background of the 2021 Higher Education Club Cup National College Students Mathematical Contest in Modeling A, according to the relevant data of the China Sky Eye (FAST) radio telescope, the main cable nodes and actuators are adjusted and controlled by mathematical modeling and computer simulation methods to realize the active reflector. The adjustment of the shape enables it to better receive the signal of the external celestial body and improve the utilization rate of the reflector, so as to achieve a higher receiving ratio of the feed cabin. In this paper, a point set mapping algorithm based on the rotation matrix of the spatial coordinate axis is proposed, that is, the mapping matrix is obtained by mathematical derivation, and the linear interpolation algorithm based on the original spherical surface and the ideal paraboloid to solve the working paraboloid is obtained. When the interpolation ratio is adjusted to 89% to satisfy the optimal solution under realistic constraints. Then, a three-dimensional spatial signal reflection model based on spatial linear invariance is proposed. Each reflective panel is used as an evaluation index. For each reflective surface, the 0-1 variable of signal accessibility on the feeder is defined. The signal is mapped to the plane where the feeder is located, which reduces a lot of computational difficulty. Finally, it is found that the panel of the feed cabin that can receive the reflected signal accounts for 19.3%. Compared with the original spherical reflection model, the working paraboloid model established in this paper has a The signal ratio has increased by 224%.

To what extent are all astrophysical, dark, compact objects both black holes (BHs) and described by the Kerr geometry? We embark on the exercise of defying the universality of this remarkable idea, often called the "Kerr hypothesis". After establishing its rationale and timeliness, we define a minimal set of reasonability criteria for alternative models of dark compact objects. Then, as proof of principle, we discuss concrete, dynamically robust non-Kerr BHs and horizonless imitators, that 1) pass the basic theoretical, and in particular dynamical, tests, 2) match (some of the) state of the art astrophysical observables and 3) only emerge at some (macroscopic) scales. These examples illustrate how the universality (at all macroscopic scales) of the Kerr hypothesis can be challenged.

In the Universe matter outside of stars and compact objects is mostly composed of collisionless plasma. The interaction of a supersonic plasma flow with an obstacle results in collisionless shocks that are often associated with intense nonthermal radiation and the production of cosmic ray particles. Motivated by simulations of non-relativistic high-Mach-number shocks in supernova remnants, we investigate the instabilities excited by relativistic electron beams in the extended foreshock of oblique shocks. The phase-space distributions in the inner and outer foreshock regions are derived with a Particle-in-Cell simulation of the shock and used as initial conditions for simulations with periodic boundary conditions to study their relaxation towards equilibrium. We find that the observed electron-beam instabilities agree very well with the predictions of a linear dispersion analysis: the electrostatic electron-acoustic instability dominates in the outer region of the foreshock, while the denser electron beams in the inner foreshock drive the gyroresonant oblique-whistler instability.

Geomagnetic storms, disturbances of Earth's magnetosphere caused by masses of charged particles being emitted from the Sun, are an uncontrollable threat to modern technology. Notably, they have the potential to damage satellites and cause instability in power grids on Earth, among other disasters. They result from high sun activity, which are induced from cool areas on the Sun known as sunspots. Forecasting the storms to prevent disasters requires an understanding of how and when they will occur. However, current prediction methods at the National Oceanic and Atmospheric Administration (NOAA) are limited in that they depend on expensive solar wind spacecraft and a global-scale magnetometer sensor network. In this paper, we introduce a novel machine learning and computer vision approach to accurately forecast geomagnetic storms without the need of such costly physical measurements. Our approach extracts features from images of the Sun to establish correlations between sunspots and geomagnetic storm classification and is competitive with NOAA's predictions. Indeed, our prediction achieves a 76% storm classification accuracy. This paper serves as an existence proof that machine learning and computer vision techniques provide an effective means for augmenting and improving existing geomagnetic storm forecasting methods.