Papers for Thursday, Feb 24 2022

The importance of alternative methods to measure the Hubble constant such as time-delay cosmography is highlighted by the recent Hubble tension. It is paramount to thoroughly investigate and rule out systematic biases in all measurement methods before we can accept new physics as the source of this tension. In this study, we perform a check for systematic biases in the lens modelling procedure of time-delay cosmography by comparing independent and blind time-delay predictions of the system WGD 2038$-$4008 from two teams using two different software programs: Glee and lenstronomy. The predicted time delays from both teams incorporate the stellar kinematics of the deflector and the external convergence from line-of-sight structures. The unblinded time-delay predictions from the two teams agree within $1.2\sigma$ implying that once the time delay is measured the inferred Hubble constant will also be mutually consistent. However, there is a $\sim$4$\sigma$ discrepancy between the power-law model slope and external shear, which is a significant discrepancy at the level of lens models before incorporating the stellar kinematics and the external convergence. We identify the difference in the reconstructed point spread function (PSF) to be the source of this discrepancy. If the same reconstructed PSF is used by both teams, then we achieve excellent agreement within $\sim$0.6$\sigma$, indicating that potential systematics stemming from source reconstruction algorithms and investigator choices are well under control. We recommend future studies to supersample the PSF as needed and marginalize over multiple algorithms/realizations for the PSF reconstruction to mitigate the systematic associated with the PSF. A future study will measure the time delays of the system WGD 2038$-$4008 and infer the Hubble constant based on our mass models.

The ultraluminous infrared galaxy IRAS 17208$-$0014 is a late-stage merger that hosts a buried active galactic nucleus (AGN). To investigate its nuclear structure, we performed high spatial resolution ($\sim0.\!\!^{\prime\prime}04\sim32\,\mathrm{pc}$) Atacama Large Millimeter/submillimeter Array (ALMA) observations in Band 9 ($\sim$450\,\micron\ or $\sim$660\,GHz), along with near-infrared AKARI spectroscopy in 2.5--5.0\,\micron. The Band 9 dust continuum peaks at the AGN location, and toward this position CO($J$=6--5) and CS($J$=14--13) are detected in absorption. Comparison with non-local thermal equilibrium calculations indicates that, within the central beam ($r\sim20\,\mathrm{pc}$), there exists a concentrated component that is dense ($10^7\,\mathrm{cm}^{-2}$) and warm ($>$200\,K) and has a large column density ($N_\mathrm{H_2}>10^{23}\,\mathrm{cm}^{-2}$). The AKARI spectrum shows deep and broad CO ro-vibrational absorption at 4.67\,\micron. Its band profile is well reproduced with a similarly dense and large column but hotter ($\sim$1000\,K) gas. The region observed through absorption in the near-infrared is highly likely in the nuclear direction, as in the sub-millimeter, but with a narrower beam including a region closer to the nucleus. The central component is considered to possess a hot structure where vibrationally excited HCN emission originates. The most plausible heating source for the gas is X-rays from the AGN. The AKARI spectrum does not show other AGN signs in 2.5--4\,\micron, but this absence may be usual for AGNs buried in a hot mid-infrared core. Besides, based on our ALMA observations, we relate various nuclear structures of IRAS 17208$-$0014 that have been proposed in the literature.

In this paper we present the X-ray analysis of SDSS DR8 redMaPPer (SDSSRM) clusters using data products from the $XMM$ Cluster Survey (XCS). In total, 1189 SDSSRM clusters fall within the $XMM$-Newton footprint. This has yielded 456 confirmed detections accompanied by X-ray luminosity ($L_{X}$) measurements. Of the detected clusters, 382 have an associated X-ray temperature measurement ($T_{X}$). This represents one of the largest samples of coherently derived cluster $T_{X}$ values to date. Our analysis of the X-ray observable to richness ($\lambda$) scaling relations has demonstrated that scatter in the $T_{X}-\lambda$ relation is roughly a third of that in the $L_{X}-\lambda$ relation, and that the $L_{X}-\lambda$ scatter is intrinsic, i.e. will not be significantly reduced with larger sample sizes. Our analysis of the scaling relation between $L_{X}$ and $T_{X}$ has shown that the fits are sensitive to the selection method of the sample, i.e. whether the sample is made up of clusters detected "serendipitously" compared to those deliberately targeted by $XMM$. These differences are also seen in the $L_{X}-\lambda$ relation and, to a lesser extent, in the $T_{X}-\lambda$ relation. Exclusion of the emission from the cluster core does not make a significant impact to the findings. A combination of selection biases is a likely, but as yet unproven, reason for these differences. Finally, we have also used our data to probe recent claims of anisotropy in the $L_{X}-T_{X}$ relation across the sky. We find no evidence of anistropy, but stress that this may be masked in our analysis by the incomplete declination coverage of the SDSS DR8 sample.

The calibration of the tip of the red giant branch (TRGB) in the I-band has a direct role in determinations of the Hubble constant, a subject of recent interest. We present a maximum likelihood (ML) method designed to obtain an independent calibration of the brightness of TRGB using Gaia parallaxes from the Early Data Release 3 (EDR3) of Milky Way field Giants at high Galactic latitude. We adopt simple parameterizations for the Milky Way stellar luminosity function and density law and and optimize the likelihood of the observed sample as a function of those parameters. Using parameters to partially constrain the luminosity function from other galaxies similar to the Milky Way for which high quality TRGB data are available, we find values of the TRGB magnitude of $ M_I^{TRGB} $ = $-3.978$ $\pm$ $0.031$ (stat) $\pm$ $0.045$ (sys) mag, where the systematic uncertainty covers the range of shape parameters found in our reference galaxies. While current data are insufficient to simultaneously characterize the shape of the Milky Way luminosity function we estimate that the photometry from Gaia Data Release 3 (mid-2022) will allow better constraints on the shape, and lower statistical uncertainties on the tip by a factor of 3. With expected releases of improved parallax measurements from Gaia, the method of calibrating the TRGB luminosity from field Giants is expected to reach $\sim$ 0.01 mag uncertainty, which is an important step toward a precise TRGB-based determination of the Hubble constant.

Fast radio bursts are brief, intense flashes of radio waves that arise from unknown sources in galaxies across the universe. Observations of the polarization properties in repeating fast radio bursts have shown they can reside in highly magnetized environments, such as in the immediate vicinity of a recent supernova or massive black hole. We have observed the actively repeating FRB 20190520B over a span of fourteen months and found that its Faraday rotation measure is both large in magnitude and rapidly varying, including two sign changes which indicate time-dependent orientation changes of the magnetic field along our line of sight. The FRB also depolarizes rapidly at lower frequencies. These phenomena can be explained in terms of multi-path propagation through a highly turbulent, dense magnetized screen within a range of 8 AU to 100 pc away from the FRB source, distinctly narrowing the possible physical configurations that could give rise to the emission seen in FRB 20190520B.

Over recent years there has been mounting evidence that accreting supermassive black holes in active galactic nuclei (AGN) and stellar mass black holes have similar observational signatures: thermal emission from the accretion disk, X-ray corona, and relativisitic jets. Further, there have been investigations into whether or not AGN have spectral states similar to that of X-ray binaries (XRBs) and what parallels can be drawn between the two using a hardness-intensity diagram (HID). To address whether AGN jets might be related to accretion states as in XRBs, we explore whether populations of radio-AGN classified according to their radio jet morphology (Fanaroff-Riley classes I and II; FR I and II), excitation class (HERG and LERG), and radio jet linear extent (compact to giant) occupy different and distinct regions of the AGN hardness-intensity diagram (total luminosity vs. hardness). We do this by cross correlating 15 catalogs of radio galaxies with the desired characteristics from the literature withXMM_Newton and Swift X-ray and ultraviolet (UV) source catalogs. We calculate the luminosity and hardness from the X-ray and UV photometry, place the sources on the AGN hardness-intensity diagram, and search for separation of populations and analogies with the XRB spectral state HID. We find that (a) FR Is and IIs, (b) HERGs and LERGs, (c) FR I-LERGs and FR II-HERGs occupy distinct areas of the HID at a statistically significant level (p-value < 0.05) and no clear evidence for population distinction between the different radio jet linear extents. The separation between FR I-LERG and FR II-HERG populations is the strongest in this work.Our results indicate that radio-loud AGN occupy distinct areas of the HID depending on the morphology and excitation class, showing strong similarities to XRBs.

The interaction of jets in High-Mass X-ray Binaries (HMXBs) with the strong winds driven by the hot companion star in the vicinity of the compact object is fundamental to understand the jet dynamics, non-thermal emission and long-term stability. However, the role of the jet magnetic field in this process is unclear. We study the dynamical role of weak and moderate-to-strong toroidal magnetic fields during the first hundreds of seconds of jet propagation, focusing on the magnetized flow dynamics and the mechanisms of energy conversion. We have developed the code L\'ostrego v1.0, a new 3D RMHD code to simulate astrophysical plasmas in Cartesian coordinates. Using this tool, we performed the first 3D RMHD numerical simulations of relativistic magnetized jets propagating through the clumpy stellar wind in a HMXB. The overall morphology and dynamics of weakly magnetized jet models is similar to previous hydrodynamical simulations, where the jet head generates a strong shock in the ambient medium and the initial over-pressure with respect to the stellar wind drives one or more recollimation shocks. In the time scales of our simulations, these jets are ballistic and seem to be more stable against internal instabilities than jets with the same power in the absence of fields. However, moderate-to-strong toroidal magnetic fields favour the development of current-driven instabilities and the disruption of the jet within the binary. A detailed analysis of the energy distribution in the relativistic outflow and the ambient medium reveals that both magnetic and internal energies can contribute to the effective acceleration of the jet. We certify that the jet feedback into the ambient medium is highly dependent on the jet energy distribution at injection, where hotter, more dilute and/or more magnetized jets are more efficient, as anticipated by feedback studies in the case of jets in active galaxies.

Neutrinos offer a unique window to the distant, high-energy universe. Several next-generation instruments are being designed and proposed to characterize the flux of TeV--EeV neutrinos. The projected physics reach of the detectors is often quantified with simulation studies. However, a complete Monte Carlo estimate of detector performance is costly from a computational perspective, restricting the number of detector configurations considered when designing the instruments. In this paper, we present a new Python-based software framework, toise, which forecasts the performance of a high-energy neutrino detector using parameterizations of the detector performance, such as the effective areas, angular and energy resolutions, etc. The framework can be used to forecast performance of a variety of physics analyses, including sensitivities to diffuse fluxes of neutrinos and sensitivity to both transient and steady state point sources. This parameterized approach reduces the need for extensive simulation studies in order to estimate detector performance, and allows the user to study the influence of single performance metrics, like the angular resolution, in isolation. The framework is designed to allow for multiple detector components, each with different responses and exposure times, and supports paramterization of both optical- and radio-Cherenkov (Askaryan) neutrino telescopes. In the paper, we describe the mathematical concepts behind toise and provide detailed instructive examples to introduce the reader to use of the framework.

Motivated by the integral field units on large aperture telescopes and proposals for ultraviolet-sensitive space telescopes to probe circumgalactic medium (CGM) emission, we survey the most promising CGM emission lines and how such observations can inform our understanding of the CGM and its relation to galaxy formation. We tie our emission estimates to HST/COS absorption measurements of ions around z= 0.2 Milky Way mass halos and motivated models for the density and temperature of gas, and we provide formulas that simplify extending our estimates to other samples and physical scenarios. We find that OIII 5007 A and NII 6583 A, which at fixed ionic column density are primarily sensitive to the thermal pressure of the gas they inhabit, may be detectable with KCWI and especially IFUs on 30 m telescopes out to half a virial radius. We comment on the implications of existing OIII and NII stacking measurements by Zhang and coworkers (2018). OV 630 A and OVI 1032,1038 A are perhaps the most promising ultraviolet lines, with motivated models predicting intensities >100 $\gamma$ cm$^{-2}$ s$^{-1}$ sr$^{-1}$ in the inner 100 kpc of Milky Way-like systems. A detection would confirm the collisionally ionized picture and constrain the density profile of the CGM. Other ultraviolet metal lines constrain the amount of gas that is actively cooling and mixing. We find that CIII 978 A and CIV 1548 A may be detectable if an appreciable fraction of the observed OVI column is associated with mixing or cooling gas. Hydrogen n>2 Lyman-series lines are too weak to be detectable, and H$\alpha$ emission within 100 kpc of Milky Way-like galaxies is within the reach of current integral field units even for the minimum signal from ionizing background fluorescence.

This study calculated astrophysical parameters, as well as kinematic and galactic orbital parameters, of the open clusters NGC 1664 and NGC 6939. The work is based on CCD UBV and Gaia photometric and astrometric data from ground and space-based observations. Considering Gaia Early Data Release 3 (EDR3) astrometric data, we determined membership probabilities of stars located in both of the clusters. We used two-color diagrams to determine $E(B-V)$ color excesses for NGC 1664 and NGC 6939 as $0.190 \pm 0.018$ and $0.380 \pm 0.025$ mag, respectively. Photometric metallicities for the two clusters were estimated as [Fe/H] = $-0.10 \pm 0.02$ dex for NGC 1664 and as [Fe/H] = $-0.06 \pm 0.01$ dex for NGC 6939. Using the reddening and metallicity calculated in the study, we obtained distance moduli and ages of the clusters by fitting PARSEC isochrones to the color-magnitude diagrams based on the most likely member stars. Isochrone fitting distances are $1289 \pm 47$ pc and $1716 \pm 87$ pc, which coincide with ages of $675 \pm 50$ Myr and $1.5 \pm 0.2$ Gyr for NGC 1664 and NGC 6939, respectively. We also derived the distances to the clusters using Gaia trigonometric parallaxes and compared these estimates with the literature. We concluded that the results are in good agreement with those given by the current study. Present day mass function slopes were calculated as $\Gamma=-1.22\pm0.33$ and $\Gamma=-1.18\pm0.21$ for NGC 1664 and NGC 6939, respectively, which are compatible with the Salpeter (1955) slope. Analyses showed that both of clusters are dynamically relaxed. The kinematic and dynamic orbital parameters of the clusters were calculated, indicating that the birthplaces of the clusters are outside the solar circle.

The San Antonio Teacher Training Astronomy Academy (SATTAA) completed its fourth annual iteration in June 2021 . While the program began as a face-to-face professional development opportunity for future and current school teachers, it transitioned to a fully online opportunity in 2020. In our efforts to offer an astronomy education program that is inclusive and particularly attentive to highly diverse populations, the transition to online programming became a core aspect of scaling up the program. The 2021 iteration featured an international facilitation team, and, for the first time, supported teachers from across the State of Texas. In this paper, we share data on how the facilitation team transitioned from a local to an international group, and on how the participant pool expanded from local to state-wide.

Capitalizing on the enthusiasm about space science in the general public, our goal as an interdisciplinary group of scholars is to design and teach a new team-taught interdisciplinary course, "Philosophy and Science of Space Exploration (PoSE)" at the University of Texas at San Antonio (UTSA) where we currently teach. We believe that this course will not only help overcome disciplinary silos to advance our understanding of space and critically examine its ethical ramifications, but also will better educate the public on how science works and help overcome the science skepticism that has unfortunately become more prominent in recent years. In what follows, we first juxtapose two seemingly contradictory trends: increased interest in space science on the one hand and increased skepticism about and distrust in science on the other. We then turn to how our anticipated Philosophy and Science of Space Exploration (PoSE) course will develop tools that could dismantle distrust in science while also enhancing the scientific and philosophical understandings of space science. We explain the content and the questions we will examine in POSE and conclude with how we will measure our success and progress.

Variability is a powerful tool to investigate properties of X-ray binaries (XRB), in particular for Ultraluminous X-ray sources (ULXs) that are mainly detected in the X-ray band. For most ULXs the nature of the accretor is unknown, although a few ULXs have been confirmed to be accreting at super-Eddington rates onto a neutron star (NS). Monitoring these sources is particularly useful both to detect transients and to derive periodicities, linked to orbital and super-orbital modulations. Here we present the results of our monitoring campaign of the galaxy NGC 925, performed with the Neil Gehrels Swift Observatory. We also include archival and literature data obtained with Chandra, XMM-Newton and NuSTAR. We have studied spectra, light-curves and variability properties on days to months time-scales. All the three ULXs detected in this galaxy show flux variability. ULX-1 is one of the most luminous ULXs known, since only 10% of the ULXs exceed a luminosity of $\sim$5$\times$10$^{40}$ erg s$^{-1}$, but despite its high flux variability we found only weak spectral variability. We classify it as in a hard ultraluminous regime of super-Eddington accretion. ULX-2 and ULX-3 are less luminous but also variable in flux and possibly also in spectral shape. We classify them as in between the hard and the soft ultraluminous regimes. ULX-3 is a transient source: by applying a Lomb-Scargle algorithm we derive a periodicity of $\sim$ 126 d, which could be associated with an orbital or super-orbital origin.

We calculated the electron-positron pair production rate at the base of the jet of 3C 120 by collisions of photons from the hot accretion flow using the measurement of its average soft gamma-ray spectrum by Compton Gamma Ray Observatory. We found that this rate approximately equals the flow rate of the leptons emitting the observed synchrotron radio-to-IR spectrum of the jet core, calculated using the extended jet model following Blandford \& Konigl. This coincidence shows the jet composition is likely to be pair-dominated. We then calculated the jet power in the bulk motion of ions, and found it greatly exceeds that achievable by the magnetically arrested disk scenario for the maximum black hole spin unless the jet contains mostly pairs. Next, we found that the magnetic flux through the synchrotron-emitting jet equals the maximum poloidal flux that can thread the black hole. Finally, we compared two estimates of the magnetization parameter at the onset of the synchrotron emission and found they are in agreement only if pairs dominate the jet content.

During a close encounter between a star and a supermassive black hole, the star can get disrupted by the black hole's tidal forces, resulting in a tidal disruption event (TDE). The accretion of the star's material onto the black hole produces strong emission in different wavelength regimes. Here we report the discovery with ROSAT of an X-ray-selected transient source in an optically non-active galaxy. At the location RA: 13h31m57.66s and Dec: -32deg3arcmin19.7arsec a sudden rise in X-ray luminosity by a factor of 8 within 8 days has been observed. Additionally, a very soft X-ray spectrum with a black-body temperature kT=0.1 keV and a peak luminosity of at least 10^43 erg/s suggest a TDE interpretation, and the observed properties are very similar to previously identified soft X-ray (ROSAT) TDEs. An optical spectrum taken of the galaxy at the position of RXJ133157.6-324319.7 six years after the X-ray outburst does not show any emission lines as would be expected from a persistent active galactic nucleus (AGN). The redshift of the galaxy is determined to be 0.051 based on absorption lines. It is therefore likely a member of the galaxy cluster Abell 3560. The rise in X-ray luminosity happens within 8 days and thus appears to be fast for such an event. No X-ray emission was detected 170 days before and 165 days after the event, and none was detected 25 years later with the Neil Gehrels Swift Observatory. The change in X-ray luminosity is at least a factor of 40.

SNe II show great photometric and spectroscopic diversity which is attributed to the varied physical characteristics of their progenitor and explosion properties. In this study, the third of a series of papers where we analyse a sample of SNe II observed by the Carnegie Supernova Project-I, we present correlations between their observed and physical properties. Our analysis shows that explosion energy is the physical property that correlates with the highest number of parameters. We recover previously suggested relationships between the hydrogen-rich envelope mass and the plateau duration, and find that more luminous SNe II with higher expansion velocities, faster declining light curves, and higher Ni masses are consistent with higher energy explosions. In addition, faster declining SNe II are also compatible with more concentrated Ni in the inner regions of the ejecta. Positive trends are found between the initial mass, explosion energy, and Ni mass. While the explosion energy spans the full range explored with our models, the initial mass generally arises from a relatively narrow range. Observable properties were measured from our grid of models to determine the effect of each physical parameter on the observed SN II diversity. We argue that explosion energy is the physical parameter causing the greatest impact on SN II diversity, when assuming standard single-star evolution as in the models used in this study. The inclusion of pre-SN models assuming higher mass loss produces a significant increase in the strength of some correlations, particularly those between the progenitor hydrogen-rich envelope mass and the plateau and optically thick phase durations. These differences clearly show the impact of having different treatments of stellar evolution, implying that changes in the assumption of standard single-star evolution are necessary for a complete understanding of SN II diversity.

Recent results of Singh et al. (2016) show that the emergence of an active region (AR) can be seen in a strengthening of the f-mode power up to two days prior of the region's formation. In the original work, ring diagram analysis was used to estimate the power evolution. In this study, we make use of the Fourier-Hankel method, essentially testing the aforementioned results with an independent method. The data is acquired from SDO/HMI, studying the ARs 11158, 11072, 11105, 11130, 11242 and 11768. Investigating the total power as a function of time, we find a similar behavior to the original work, which is an enhancement of f-mode power about one to three days prior to AR emergence. Analysis of the absorption coefficient $\alpha$, yielded by a Fourier-Hankel analysis, shows neither absorption ($\alpha > 0$) nor emission ($\alpha < 0$) of power during the enhancement. Finding no changes of the absorption coefficient (i.e. $\alpha = 0$) is an important result, as it narrows down the possible physical interpretation of the original f-mode power enhancement, showing that no directional dependence (in the sense of inward and outward moving waves) is present.

StrayCats, the catalog of NuSTAR stray light observations, contains data from bright X-ray sources that fall within crowded source regions. These observations offer unique additional data with which to monitor sources like X-ray binaries that show variable timing behavior. In this work, we present a timing analysis of stray light data of the high mass X-ray binary SMC X-1, the first scientific analysis of a single source from the StrayCats project. We describe the process of screening stray light data for scientific analysis, verify the orbital ephemeris, and create both time and energy resolved pulse profiles. We find that the orbital ephemeris of SMC X-1 is unchanged and confirm a long-term spin up rate of $\dot{\nu}=(2.52\pm0.03)\times10^{-11}$ Hz s$^{-1}$. We also note that the shape of SMC X-1's pulse profile, while remaining double-peaked, varies significantly with time and only slightly with energy.

In the manuscript, central black hole (BH) mass is estimated in the distant TDE (tidal disruption event) of {\it Swift} J2058.4+0516 as the second candidate of relativistic jet birth related to TDE. {\it Swift} J2058.4+0516 have quite different BH masses estimated through different indirect methods in the literature. Therefore, it is necessary and interesting to determine the central BH mass in {\it Swift} J2058.4+0516 by one another independent method. Here, based on the theoretical TDE model applied to describe the long-term time-dependent X-ray variabilities of {\it Swift} J2058.4+0516, the central BH mass can be well determined to be around $1.05_{-0.29}^{+0.39}\times10^5{\rm M_\odot}$, after kind considerations of suggested intrinsic beaming effects from such relativistic jet tightly related to TDE. Moreover, the {\it Swift} J2058.4+0516 is an unique object in the space of BH masses versus energy transfer efficiencies of the reported TDE candidates, providing interesting clues to detect and/or anticipate candidates of relativistic TDE to make the birth of relativistic jets.

The scattering of cosmic microwave background (CMB) radiation in galaxy clusters induces polarization signals according to the quadrupole anisotropy in the photon distribution at the cluster location. This `remote quadrupole' derived from the measurements of the induced polarization provides an opportunity for reconstructing primordial fluctuations on large scales. We discuss that comparing the local CMB quadrupoles predicted by these reconstructed primordial fluctuations and the direct measurements done by CMB satellites may enable us to test the dark energy beyond cosmic variance limits.

Ubiquitous transition region (TR) network jets are considered to be substantial sources of mass and energy to the corona and solar wind. We conduct a case study of a network jet to better understand the nature of mass flows along its length and the energetics involved in its launch. We present an observation of a jet with the Interface Region Imaging Spectrograph (IRIS), while also using data from the Solar Dynamics Observatory (SDO) to provide further context. The jet was located within a coronal hole close to the disk center. We find that a blueshifted secondary component of TR emission is associated with the jet and is persistent along its spire. This component exhibits upward speeds of approximately 20-70 km s$^{-1}$ and shows enhanced line broadening. However, plasma associated with the jet in the upper chromosphere shows downflows of 5-10 km s$^{-1}$. Finally, the jet emanates from a seemingly unipolar magnetic footpoint. While a definitive magnetic driver is not discernible for this event, we infer that the energy driving the network jet is deposited at the top of the chromosphere, indicating that TR network jets are driven from the mid-atmospheric layers of the Sun. The energy flux associated with the line broadening indicates that the jet could be powered all the way into the solar wind.

Ethanol (CH$_3$CH$_2$OH) is a relatively common molecule, often found in star forming regions. Recent studies suggest that it could be a parent molecule of several so-called interstellar complex organic molecules (iCOMs). Yet, the formation route of this species remains debated. In the present work, we study the formation of ethanol through the reaction of CCH with one H$_2$O molecule belonging to the ice, as a test case to investigate the viability of chemical reactions based on a "radical + ice component" scheme as an alternative mechanism for the synthesis of iCOMs, beyond the usual radical-radical coupling. This has been done by means of DFT calculations adopting two clusters of 18 and 33 water molecules as ice models. Results indicate that CH$_3$CH$_2$OH can potentially be formed by this proposed reaction mechanism. The reaction of CCH with H$_2$O on the water ice clusters can be barrierless (thanks to the help of boundary icy water molecules acting as proton transfer assistants) leading to the formation of vinyl alcohol precursors (H$_2$CCOH and CHCHOH). Subsequent hydrogenation of vinyl alcohol yielding ethanol is the only step presenting a low activation energy barrier. We finally discuss the astrophysical implications of these findings.

Recent observations found close-in planets with significant atmospheres of hydrogen and helium in great abundance. These are the so-called super-Earths and mini-Neptunes. Their atmospheric composition suggests that they formed early during the gas-rich phase of the circumstellar disk and were able to avoid becoming hot Jupiters. As a possible explanation, recent studies explored the recycling hypothesis and showed that atmosphere-disk recycling is able to fully compensate for radiative cooling and thereby halt Kelvin-Helmholtz contraction to prevent runaway gas accretion. To understand the parameters that determine the efficiency of atmospheric recycling, we extend our earlier studies by exploring the effects of the core mass, the effect of circumstellar gas on sub-Keplerian orbits (headwind), and the optical depth of the surrounding gas on the recycling timescale. Additionally, we analyze their effects on the size and mass of the forming atmosphere. For the explored parameter space, all simulations eventually reach an equilibrium where heating due to hydrodynamic recycling fully compensates radiative cooling. In this equilibrium, the atmosphere-to-core mass ratio stays well below $10 \, \%$, preventing the atmosphere from becoming self-gravitating and entering runaway gas accretion. Higher core masses cause the atmosphere to become turbulent, which further enhances recycling. Even for our highest core mass of $10 \, M_\mathrm{Earth}$, atmosphere-disk recycling is efficient enough to fully compensate for radiative cooling and prevent the atmosphere from becoming self-gravitating. Hence, in-situ formation of hot Jupiters is very unlikely, and migration of gas giants is a key process required to explain their existence. Our findings imply that atmosphere-disk recycling is the most natural explanation for the prevalence of close-in super-Earths and mini-Neptunes.

The relation between the integrated Sunyaev-Zeldovich (SZ) $y$-decrement versus halo mass ($Y$-$M$) can potentially constrain galaxy formation models, if theoretical and observational systematics can be properly assessed. We investigate the $Y-M$ relation in the SIMBA and IllustrisTNG-100 cosmological hydrodynamic simulations, quantifying the effects of feedback, line-of-sight projection, and beam convolution. We find that SIMBA's AGN jet feedback generates strong deviations from self-similar expectations for the $Y-M$ relation, especially at $M_{500}<10^{13}M_{\odot}$. In SIMBA this is driven by suppressed in-halo $y$ contributions owing to lowered halo baryon fractions. IllustrisTNG results more closely resemble SIMBA without jets. Projection of line-of-sight structures weakens these model differences slightly, but they remain significant at mostly group and lower halo masses. In contrast, beam smearing at $\textit{Planck}$ resolution makes the models indistinguishable, and both models appear to agree well with $\textit{Planck}$ data down to the lowest masses probed. We show that the arcminute resolution expected from forthcoming facilities would retain the differences between model predictions, and thereby provide strong constraints on AGN feedback.

We present a novel physically-motivated parametrized temperature model for phasecurve retrieval, able to self-consistently assess the variation in the thermal structure in multidimensions. To develop this approach we drew motivation from both full three-dimensional general circulation models and analytic formulations, accounting for the dominant dynamical feature of tidally-locked planets, the planetary jet. Our formulation shows notable flexibility. It can generate planetary jets of various characteristics and redistribution efficiencies seen in the literature, including both standard eastward and unusual westward offset hotspots, as well as more exotic configurations for potential future observations. In our modelling scheme we utilize a tractable set of parameters efficient enough to enable future Bayesian analysis and, in addition to the resolved temperature structure, we return physical insights not yet derived from retrievals: the amplitude and the phase offset, and the location and the extent of the equatorial jet.

The presence of Multiple Stellar Populations (MSPs) in Galactic Globular Clusters (GCs) is a poorly understood phenomenon. By probing different spectral ranges that are affected by different absorption lines using the multi-band photometric survey S-PLUS, we study four GCs -- NGC 104, NGC 288, NGC 3201 and NGC 7089 -- that span a wide range in metallicities. With the combination of broad and narrow-band photometry in 12 different filters from 3485A (u) to 9114A (z), we identified MSPs along the rectified red-giant branch in colour-magnitude diagrams (CMDs) and separated them using a K-means clustering algorithm. Additionally, we take advantage of the large Field of View of the S-PLUS detector to investigate radial trends in our sample. We report on six colour combinations that can be used to successfully identify two stellar populations in all studied clusters and show that they can be characterized as Na-rich and Na-poor. For both NGC 288 and NGC 7089, their radial profiles show a clear concentration of 2P. This directly supports the formation theories that propose an enrichment of the intra-cluster medium and subsequent star formation in the more dense central regions. However, in the case of NGC 3201, the trend is reversed. The 1P is more centrally concentrated, in direct contradiction with previous literature studies. NGC 104 shows a well-mixed population. We also constructed radial profiles up to 1 half-light radius of the clusters with HST data to highlight that radial differences are lost in the inner regions of the GCs and that wide-field studies are essential when studying this.

The link between the surface temperature of Mercury and the exosphere sodium content has been investigated. Observations show that, along the orbit of Mercury, two maxima of total Na content are present: one at aphelion and one at perihelion. Previous models, based on a simple thermal map, were not able to reproduce the aphelion peak. Here we introduce a new thermophysical model giving soil temperatures as an input for the IAPS exospheric model already used in the past with the input of a simple thermal map. By comparing the reference model output with the new one, we show that such improved surface temperature map is crucial to explain the temporal variability of Sodium along the orbit.

Globular clusters (GCs) are proxies of the formation assemblies of their host galaxies. However, few studies exist targeting GC systems of spiral galaxies up to several effective radii. Through 12-band Javalambre Photometric Local Universe Survey (J-PLUS) imaging, we study the point sources around the M81/M82/NGC3077 triplet in search of new GC candidates. We develop a tailored classification scheme to search for GC candidates based on their similarity to known GCs via a principal components analysis (PCA) projection. Our method accounts for missing data and photometric errors. We report 642 new GC candidates in a region of 3.5 deg$^2$ around the triplet, ranked according to their Gaia astrometric proper motions when available. We find tantalising evidence for an overdensity of GC candidate sources forming a bridge connecting M81 and M82. Finally, the spatial distribution of the GC candidates $(g-i)$ colours is consistent with halo/intra-cluster GCs, i.e. it gets bluer as they get further from the closest galaxy in the field. We further employ a regression-tree based model to estimate the metallicity distribution of the GC candidates based on their J-PLUS bands. The metallicity distribution of the sample candidates is broad and displays a bump towards the metal-rich end. Our list increases the population of GC candidates around the triplet by 3-fold, stresses the usefulness of multi-band surveys in finding these objects, and provides a testbed for further studies analysing their spatial distribution around nearby (spirals) galaxies.

We present MeqSilhouette v2.0 (MeqSv2), a fully polarimetric, time-and frequency-resolved synthetic data generation software for simulating millimetre (mm) wavelength very long baseline interferometry (VLBI) observations with heterogeneous arrays. Synthetic data are a critical component in understanding real observations, testing calibration and imaging algorithms, and predicting performance metrics of existing or proposed sites. MeqSv2 applies physics-based instrumental and atmospheric signal corruptions constrained by empirically-derived site and station parameters to the data. The new version is capable of applying instrumental polarization effects and various other spectrally-resolved effects using the Radio Interferometry Measurement Equation (RIME) formalism and produces synthetic data compatible with calibration pipelines designed to process real data. We demonstrate the various corruption capabilities of MeqSv2 using different arrays, with a focus on the effect of complex bandpass gains on closure quantities for the EHT at 230 GHz. We validate the frequency-dependent polarization leakage implementation by performing polarization self-calibration of synthetic EHT data using PolSolve. We also note the potential applications for cm-wavelength VLBI array analysis and design and future directions.

In this study, we exhibit a number elementary strategies that might be at disposal in diverse computational applications in the GEANT4 simulations with the purpose of hemispherical particle sources. To further detail, we initially generate random points on a spherical surface for a sphere of a practical radius by employing Gaussian distributions for the three components of the Cartesian coordinates, thereby obtaining a generating surface for the initial positions of the corresponding particles. Since we do not require the half bottom part of the produced spherical surface for our tomographic applications, we take the absolute value of the vertical component in the Cartesian coordinates by leading to a half-spherical shell, which is traditionally called a hemisphere. Last but not least, we direct the generated particles into the target material to be irradiated by favoring a selective momentum direction that is based on the vector construction between the random point on the hemispherical surface and the origin of the target material, hereby optimizing the particle loss through the source biasing. In the end, we incorporate our strategy by using G4ParticleGun in the GEANT4 code. Furthermore, we also exhibit a second scheme that is based on the coordinate transformation from the spherical coordinates to the Cartesian coordinates, thereby reducing the number of random number generators. While we plan to exert our strategy in the computational practices for muon scattering tomography, this source scheme might find its straightforward applications in different neighboring fields including but not limited to atmospheric sciences, space engineering, and astrophysics where a 3D particle source is a necessity for the modeling goals.

We report the detection of the secondary eclipse of the hot Jupiter HD 209458b in optical/visible light using the CHEOPS space telescope. Our measurement of 20.4 +/- 3.3 ppm translates into a geometric albedo of A_g = 0.096 +/- 0.016. The previously estimated dayside temperature of about 1500 K implies that our geometric albedo measurement consists predominantly of reflected starlight and is largely uncontaminated by thermal emission. This makes the present result one of the most robust measurements of A_g for any exoplanet. Our calculations of the bandpass-integrated geometric albedo demonstrate that the measured value of A_g is consistent with a cloud-free atmosphere, where starlight is reflected via Rayleigh scattering by hydrogen molecules, and the water and sodium abundances are consistent with stellar metallicity. We predict that the bandpass-integrated TESS geometric albedo is too faint to detect and that a phase curve of HD 209458b observed by CHEOPS would have a distinct shape associated with Rayleigh scattering if the atmosphere is indeed cloud free.

We present a review of the observations of the solar F-corona from space with a special emphasis of the 25 years of continuous monitoring achieved by the LASCO-C2 and C3 coronagraphs. Our work includes images obtained by the navigation cameras of the Clementine spacecraft, the SECCHI/HI-1A heliospheric imager onboard STEREO-A, and the Wide Field Imager for Solar Probe onboard the Parker Solar Probe. The connection to the zodiacal light is considered based on ground- and space-based observations, prominently from the past Helios, IRAS, COBE, and IRAKI missions. The characteristic radiance profiles along the equatorial and polar directions follow power laws in the 5{\deg}-50{\deg} range of elongation, with constant power exponents of -2.33 and -2.55. Both profiles connect extremely well to the corresponding standard profiles of the zodiacal light. The LASCO equatorial profile exhibits a shoulder implying a 17% decrease of the radiance within 10Rsun that may be explained by the disappearance of organic materials within 0.3 AU. LASCO detected for the first time a secular variation of the F-corona, an increase at a rate of 0.46% per year of the integrated radiance in the LASCO-C3 FoV. This is likely the first observational evidence of the role of collisions in the inner zodiacal cloud. A composite of C2 and C3 images produced the LASCO reference map of the radiance of the F-corona from 2 to 30Rsun and, by combining with ground-based measurements, the LASCO extended map from 1 to 6 Rsun. The plane of symmetry of the inner zodiacal cloud is strongly warped, its inclination increasing towards the planes of the inner planets and ultimately the solar equator. In contrast, its longitude of ascending node is found to be constant and equal to 87.6{\deg}. LASCO did not detect any small scale structures such as putative rings occasionally reported during solar eclipses.

We present a statistical analysis of power distribution of oscillations in a plage region in active region NOAA AR12651, observed jointly with ALMA (Atacama Large Millimeter/Submillimeter Array), IRIS (Interface Region Imaging Spectrograph), and SDO (Solar Dynamics Observatory). We employ coordinated ALMA Band-6 (1.25 mm) brightness temperature maps, IRIS Slit-Jaw Images in 2796 {\AA} passband, and observations in six passbands (1600 {\AA}, 304 {\AA}, 131 {\AA}, 171 {\AA}, 193 {\AA} and 211 {\AA}) of AIA (Atmospheric Imaging Assembly) onboard SDO. We perform Lomb-Scargle transforms to study the distribution of oscillation power over the observed region by means of dominant period maps and power maps. We study spatial association of oscillations through the atmosphere mapped by the different passbands, with focus on the correlation of power distribution of ALMA oscillations with others. We do not observe any significant association of ALMA oscillations with IRIS and AIA oscillations. While the global behavior of ALMA dominant oscillations shows similarity with that of transition region and coronal passbands of AIA, the ALMA dominant period maps and power maps do not show any correlation with those from the other passbands. The spatial distribution of dominant periods and power in different period intervals of ALMA oscillations is uncorrelated with any other passband. We speculate the non-association of ALMA oscillations with those of IRIS and AIA be due to significant variations in the height of formation of the millimeter continuum observed by ALMA. Additionally, the fact that ALMA directly maps the brightness temperature, in contrast to the intensity observations by IRIS and AIA, can result in the very different intrinsic nature of the ALMA oscillations compared to the IRIS and AIA oscillations.

Presolar stardust grains found in primitive meteorites are believed to retain the isotopic composition of stellar outflows at the time of grain condensation. Therefore, laboratory measurements of their isotopic ratios represent sensitive probes for investigating open questions related to stellar evolution, stellar explosions, nucleosynthesis, mixing mechanisms, dust formation, and galactic chemical evolution. For a few selected presolar grains, classical novae have been discussed as a potential source. For SiC, silicate, and graphite presolar grains, the association is based on the observation of small $N(^{12}$C)/$N(^{13}$C) and $N(^{14}$N)/$N(^{15}$N) number abundance ratios compared to solar values, and abundance excesses in $^{30}$Si relative to $^{29}$Si, as previously predicted by models of classical novae. We report on a direct measurement of the $^{29}$Si(p,$\gamma$)$^{30}$P reaction, which strongly impacts simulated $\delta ^{29}$Si values from classical novae. Our new experimental $^{29}$Si(p,$\gamma$)$^{30}$P thermonuclear reaction rate differs from previous results by up to 50\% in the classical nova temperature range ($T$ $=$ $100$ $-$ $400$~MK), while the rate uncertainty is reduced by up to a factor of $3$. Using our new reaction rate in Monte Carlo reaction network and hydrodynamic simulations of classical novae, we estimate $\delta ^{29}$Si values with much reduced uncertainties. Our results establish $\delta ^{29}$Si values measured in presolar grains as a sensitive probe for assessing their classical nova paternity. We also demonstrate that $\delta ^{30}$Si values from nova simulations are presently not a useful diagnostic tool unless the large uncertainty of the $^{30}$P(p,$\gamma$)$^{31}$S reaction rate can be significantly reduced.

Cosmic rays represent one of the most important energy transformation processes of the universe. They bring information about the surrounding universe, our galaxy, and very probably also the extragalactic space, at least at the highest observed energies. More than one century after their discovery, we have no definitive models yet about the origin, acceleration and propagation processes of the radiation. The main reason is that there are still significant discrepancies among the results obtained by different experiments located at ground level, probably due to unknown systematic uncertainties affecting the measurements. In this document, we will focus on the detection of galactic cosmic rays from ground with air shower arrays up to 10$^{18}$ eV. The aim of this paper is to discuss the conflicting results in the 10$^{15}$ eV energy range and the perspectives to clarify the origin of the so-called `knee' in the all-particle energy spectrum, crucial to give a solid basis for models up to the end of the cosmic ray spectrum. We will provide elements useful to understand the basic techniques used in reconstructing primary particle characteristics (energy, mass, and arrival direction) from the ground, and to show why indirect measurements are difficult and results are still conflicting.

Thermal ionization is a critical process at temperatures T > 10 3 K, particularly during star formation. An increase in ionization leads to a decrease in nonideal magnetohydrodynamics (MHD) resistivities, which has a significant impact on protoplanetary disks and protostar formation. We developed an extension of the fast computational ionization method presented in our recent paper to include thermal ionization. The model can be used to inexpensively calculate the density of ions and electrons and the electric charge of each size of grains for an arbitrary size distribution. This tool should be particularly useful for the self-consistent calculation of nonideal MHD resistivities in multidimensional simulations, especially of protostellar collapse and protoplanetary disks.

Fast Radio Bursts (FRBs) are extremely luminous and brief signals (with duration of milliseconds or even shorter) of extragalactic origin. Despite the fact that hundreds of FRBs have been discovered to date, their nature still remains unclear. Precise localizations of FRBs can unveil their host galaxies and local environments -- and thus shed light on the physical processes that led to the burst production. However, this has only been achieved for a few FRBs to date. The European VLBI Network (EVN) is currently the only instrument capable of localizing FRBs down to the milliarcsecond level. This level of precision was critical to associate the first localized FRB, 20121102A, to a star-forming region in a low-metallicity dwarf galaxy and physically related it to a compact persistent radio source. Analogously, a second repeating FRB, 20180916B, was found to just outside the edge of a prominent star-forming region of a nearby spiral galaxy. The PRECISE project (Pinpointing REpeating ChIme Sources with EVN dishes), starting from 2019, has observed hundreds of hours per year with a subset of EVN telescopes with the goal of localizing repeating FRBs discovered by the CHIME/FRB Collaboration. The ultimate goal of PRECISE is to disentangling the environments where FRBs can be produced. Here we present the state of the art of the FRB field, the PRECISE project, and the localizations achieved until now, which have unveiled a variety of environments where FRBs can be found that challenges the current models.

We present an extensive exploration of the impact of 29 physical parameters in the oxygen abundance for a sample of 299 star-forming galaxies extracted from the extended CALIFA sample. We corroborate that the stellar mass is the physical parameter that better traces the observed oxygen abundance (i.e., the mass-metallicity relation, MZR), while other physical parameters could play a potential role in shaping this abundance, but with a lower significant impact. We find that the functional form that best describes the MZR is a third-order polynomial function. From the residuals between this best functional form and the MZR, we find that once considered the impact of the mass in the oxygen abundance, the other physical parameters do not play a significant secondary role in shaping the oxygen abundance in these galaxies (including the gas fraction or the star formation rate). Our analysis suggests that the origin of the MZR is related to the chemical enrichment evolution of the interstellar medium due, most likely, to the build-up of stellar mass in these star-forming galaxies.

Axion-like particles (ALPs) are very light, neutral, spin zero bosons predicted by many theories which try to complete the standard model of elementary particles. ALPs interact primarily with two photons and can generate photon-ALP oscillations in the presence of an external magnetic field. They are attracting increasing interest since photon-ALP oscillations produce deep consequences in astrophysics particularly in the very-high-energy (VHE) band. Two hints for the existence of an ALP have recently been proposed. In this paper, we study another effect of the photon-ALP interaction: the change of the polarization state of photons. In particular, we study the propagation of the photon-ALP beam starting where photons are produced - we consider photons generated in a galaxy cluster or in the jet of a blazar - crossing several magnetized media (blazar jet, host galaxy, galaxy cluster, extragalactic space, Milky Way) up to their arrival at the Earth, where photons can be detected. In the presence of photon-ALP interaction, we analyze the photon survival probability $P_{\gamma \to \gamma}$ and the corresponding photon degree of linear polarization $\Pi_L$ for observed energies in the range $(1-10^{15}) \, \rm eV$. We observe that photons, which are expected as unpolarized in the absence of ALPs, are made partially polarized by photon-ALP interaction. Our findings about the X-ray and high-energy bands can be tested by current and planned observatories like IXPE, Polstar, COSI, e-ASTROGAM and AMEGO. We also discover a peculiar feature in the VHE band, where photons at energies above $ \sim 1 \, \rm TeV$ are fully polarized because of photon-ALP interaction. A possible detection of this feature would represent a proof for the existence of an ALP, but, unfortunately, current technologies do not allow yet to detect photon polarization up to so high energies.

The chromosphere above active regions (ARs) on the Sun hosts magnetized supersonic downflows. Studies of these supersonic downflows help to decipher the magnetic fine structure and dynamics of the chromosphere. We perform a statistical analysis of the magnetized supersonic downflows in a number of ARs and survey their characteristics. We analyze spectro-polarimetric scans of parts of 13 ARs obtained in the infrared He I 10830 \r{A} triplet formed in the upper chromosphere recorded with the GREGOR Infrared Spectrograph (GRIS) mounted at the GREGOR solar telescope. We retrieve the line-of-sight velocities and the magnetic field vector using the HeLIx+ inversion code that assumes Milne-Eddington atmospheres. We find magnetized supersonic downflows in all the ARs, with larger area coverage by such flows in ARs observed during their emerging phase. The fact that supersonic downflows were detected in all scans, though they cover only a small fraction, 0.2--6.4%, of the observed field-of-view, suggests that they are a common phenomenon in the upper chromospheres of ARs. The supersonic downflows are found to be associated with many AR features such as pores, sunspot umbrae, sunspot penumbrae, light bridges, plages, He I loops as part of arch filament systems characteristic of emerging fields, and filaments. Although several mechanisms are identified to be causing the supersonic downflows, by far the most common one appears to be the draining of plasma along the legs of rising magnetic loops. The loops mainly drain into forming pores. The line-of-sight velocities of the supersonic downflows reach up to 49 kms-1 and the velocity distribution shows multiple populations. Almost 92% of these supersonic downflows coexist with a subsonic flow component. The weaker, more horizontal fields associated with the supersonic component suggests that it is formed above the subsonic component.

A lattice quantizer approximates an arbitrary real-valued source vector with a vector taken from a specific discrete lattice. The quantization error is the difference between the source vector and the lattice vector. In a classic 1996 paper, Zamir and Feder show that the globally optimal lattice quantizer (which minimizes the mean square error) has white quantization noise: for a uniformly distributed source, the covariance of the error is the identity matrix, multiplied by a positive real factor. We generalize the theorem, showing that the same property holds (i) for any locally optimal lattice quantizer and (ii) for an optimal product lattice, if the component lattices are themselves locally optimal. We derive an upper bound on the normalized second moment (NSM) of the optimal lattice in any dimension, by proving that any lower- or upper-triangular modification to the generator matrix of a product lattice reduces the NSM. Using these tools and employing the best currently known lattice quantizers to build product lattices, we construct improved lattice quantizers in dimensions 13 to 15, 17 to 23, and 25 to 48. In some dimensions, these are the first reported lattices with normalized second moments below the Zador upper bound.

We present the first atlas of the continuous gravitational wave sky, produced using LIGO O3a public data. For each 0.045 Hz frequency band and every point on the sky the atlas provides upper limits, signal-to-noise ratios (SNR) and frequencies where the search measures the maximum SNR. The results presented in the atlas are produced with the Falcon pipeline and cover nearly monochromatic gravitational wave signals in the 500-1000 Hz band, with up to +/-5e-11 Hz/s frequency derivative. Compared to the most sensitive results previously published (also produced with the Falcon pipeline) our upper limits are 50% more constraining. Neutron stars with ellipticity of 1e-8 can be detected up to 150 pc away, while allowing for a large fraction of the stars' energy to be lost through non-gravitational channels.

We demonstrate that the dynamics of neural networks trained with gradient descent and the dynamics of scalar fields in a flat, vacuum energy dominated Universe are structurally profoundly related. This duality provides the framework for synergies between these systems, to understand and explain neural network dynamics and new ways of simulating and describing early Universe models. Working in the continuous-time limit of neural networks, we analytically match the dynamics of the mean background and the dynamics of small perturbations around the mean field, highlighting potential differences in separate limits. We perform empirical tests of this analytic description and quantitatively show the dependence of the effective field theory parameters on hyperparameters of the neural network. As a result of this duality, the cosmological constant is matched inversely to the learning rate in the gradient descent update.

China is planning to construct a new space-borne gravitational-wave (GW) observatory, the TianQin project, in which the spaceborne telescope is an important component in laser interferometry. The telescope is aimed to transmit laser beams between the spacecrafts for the measurement of the displacements between proof-masses in long arms. The telescope should have ultra-small wavefront deviation to minimize noise caused by pointing error, ultra-stable structure to minimize optical path noise caused by temperature jitter, ultra-high stray light suppression ability to eliminate background noise. In this paper, we realize a telescope system design with ultra-stable structure as well as ultra-low wavefront distortion for the space-based GW detection mission. The design requirements demand extreme control of high image quality and extraordinary stray light suppression ability. Based on the primary aberration theory, the initial structure design of the mentioned four-mirror optical system is explored. After optimization, the maximum RMS wavefront error is less than lamda/300 over the full field of view (FOV), which meets the noise budget on the telescope design. The stray light noise caused by the back reflection of the telescope is also analyzed. The noise at the position of optical bench is less than 10-10 of the transmitted power, satisfying the requirements of space gravitational-wave detection. We believe that our design can be a good candidate for TianQin project, and can also be a good guide for the space telescope design in any other similar science project.

Editorial of a special issue on dark matter & modified gravity, distributed across the journals Studies in History and Philosophy of Modern Physics and Studies in History and Philosophy of Science. Published version of the open access editorial (in SHPS) available here: https://doi.org/10.1016/j.shpsa.2021.08.015. The six papers are collected here: https://www.sciencedirect.com/journal/studies-in-history-and-philosophy-of-science-part-b-studies-in-history-and-philosophy-of-modern-physics/special-issue/10CR71RJLWM.

The search for dark matter through indirect detection remains a promising avenue to decipher the nature of this elusive yet dominant component of matter in the universe. Dark-matter particles produced in the early universe annihilate or decay to a set of Standard-Model particles that can undergo complex sequences of processes, including strong and electromagnetic radiation, hadronization, and hadron decays, to produce stable particles. Antiprotons produced in this way may leave footprints in experiments such as AMS-02. Several groups have reported an excess of events in the antiproton flux in the rigidity range of $10$-$20$ GV. However, the theoretical modeling of baryon production is not straightforward and relies in part on phenomenological models in Monte Carlo event generators. The associated theoretical uncertainties have so far not been systematically quantified in this context. In this Letter we assess the impact of QCD uncertainties on the spectra of antiprotons from dark-matter annihilation. As a proof-of-principle, we show that within a Supersymmetric scenario these uncertainties can be as large as the experimental errors of the AMS-02 data in the region of the excess.

The purpose of our present work is to investigate some new features of a static anisotropic relativistic hybrid compact star composed of strange quark matter (SQM) in the inner core and normal baryonic matter distribution in the crust. Here we apply the simplest form of the phenomenological MIT bag model equation of state $p_q = \frac{1}{3}(\rho_q - 4B_g)$ to correlate the density and pressure of strange quark matter within the stellar interior, whereas radial pressure and matter density due to baryonic matter are connected by the simple linear equation of state $p_r = \alpha \rho - \beta$. In order to obtain the solution of the Einstein field equations, we have used the Tolman-Kuchowicz {\em ansatz} [Tolman, Phys Rev 55:364, 1939; Kuchowicz, Acta Phys Pol 33:541, 1968] and further derivation of the arbitrary constants from some physical conditions. Here, we examine our proposed model graphically and analytically in detail for physically plausible conditions. In particular, for this investigation, we have reported on the compact object Her $X-1$ [Mass=$(0.98 \pm 0.12)M_{\odot}$; Radius= $8.1_{-0.41}^{+0.41}$ km] in our paper as a strange quark star candidate. In order to check the physical validity and stability of our suggested model, we have performed various physical tests both analytically and graphically, namely, dynamical equilibrium of applied forces, energy conditions, compactness factor, and surface redshift etc. Finally, we have found that our present model meets all the necessary physical requirements for a realistic model and can be studied for strange quark stars (SQS).

The theory of General Relativity was established on a spacetime manifold equipped with a metric tensor, $(\mathcal{M}_4,\text{g})$, and the connection on $\mathcal{M}_4$ identified with the Levi-Civita one. Even though there are valid reasons to assume a torsionless manifold that preserves the metric, it was shown that dealing away with these assumptions the Levi-Civita condition can be reproduced at the level of equations of motion of GR. It was not long before the equivalence of General Relativity between the two descriptions, known as the Palatini or first-order formalism in which the connection is independent of the metric, and the conventional metric or second-order formalism, was broken for more complicated actions involving higher-order curvature invariants and/or nonminimal couplings between the gravitational and matter sector. Nowadays these types of theories are prominent in modeling inflation where they have found major success. Since the paradigm of inflation is fused with the gravitational degrees of freedom and thus their parametrisation, it is interesting to understand how the predictions of these models differ between the two formulations. One of the outstanding models of inflation is the Starobinsky or quadratic gravity model. However in the Palatini formalism the scalar degree of freedom sourced by the $R^2$ term is nondynamical and is unable to drive an inflationary phase. In order for inflation to be realised in the first-order formalism the Starobinsky model has to be coupled with a fundamental scalar field that will assume the role of the inflaton. In this thesis we investigate different inflationary scenarios, starting with previously ruled-out models, where we find that the $R^2$ term has a significant role in flattening the Einstein-frame inflaton potential and thus giving the opportunity for these models to come in contact with observations.

The underlying nonlinear mechanisms behind the operation of travelling-wave parametric amplifiers (TWPAs) are important in determining their performance in terms of added noise, maximum gain, and bandwidth. We describe a method of characterising the underlying nonlinearity of a superconducting material in terms of its dissipative-reactive ratio and the response time of the underlying microscopic processes. We describe and calculate the different behaviour arising from the equilibrium supercurrent nonlinearity, which has low dissipation and fast response time, and the non-equilibrium heating nonlinearity, which has high dissipation and slow response time. We have fabricated TWPAs based on Al and Ti, and characterised their nonlinearities using our analysis. For both Al and Ti, the measured dissipative-reactive ratios and response times are quantitatively similar to predictions for the non-equilibrium heating nonlinearity. In line with this, we were able to obtain more than 20 dB of peak power gain, although only over a narrow bandwidth of a few kilohertz.