Papers for Friday, Feb 25 2022

We present new ALMA Band 7 observations of the edge-on debris disc around the M1V star GSC 07396-00759. At ~20 Myr old and in the beta Pictoris Moving Group along with AU Mic, GSC 07396-00759 joins it in the handful of low mass M-dwarf discs to be resolved in the sub-mm. With previous VLT/SPHERE scattered light observations we present a multi-wavelength view of the dust distribution within the system under the effects of stellar wind forces. We find the mm dust grains to be well described by a Gaussian torus at 70 au with a FWHM of 48 au and we do not detect the presence of CO in the system. Our ALMA model radius is significantly smaller than the radius derived from polarimetric scattered light observations, implying complex behaviour in the scattering phase function. The brightness asymmetry in the disc observed in scattered light is not recovered in the ALMA observations, implying that the physical mechanism only affects smaller grain sizes. High resolution follow-up observations of the system would allow investigation into its unique dust features as well as provide a true coeval comparison for its smaller sibling AU Mic, singularly well observed amongst M-dwarfs systems.

The Compton Spectrometer and Imager (COSI) is a balloon-borne compact Compton telescope designed to survey the 0.2-5 MeV sky. COSI's energy resolution of $\sim$0.2% at 1.8 MeV, single-photon reconstruction, and wide field of view make it capable of studying astrophysical nuclear lines, particularly the 1809 keV $\gamma$-ray line from decaying Galactic $^{26}$Al. Most $^{26}$Al originates in massive stars and core-collapse supernova nucleosynthesis, but the path from stellar evolution models to Galaxy-wide emission remains unconstrained. In 2016, COSI had a successful 46-day flight on a NASA superpressure balloon. Here, we detail the first search for the 1809 keV $^{26}$Al line in the COSI 2016 balloon flight using a maximum likelihood analysis. We find a Galactic $^{26}$Al flux of $(8.6 \pm 2.5) \times 10^{-4}$ ph cm$^{-2}$ s$^{-1}$ within the Inner Galaxy ($|\ell| \leq 30^{\circ}$, $|b| \leq 10^{\circ}$) with 3.7$\sigma$ significance above background. Within uncertainties, this flux is consistent with expectations from previous measurements by SPI and COMPTEL. This analysis demonstrates COSI's powerful capabilities for studies of $\gamma$-ray lines and underscores the scientific potential of future compact Compton telescopes. In particular, the next iteration of COSI as a NASA Small Explorer satellite has recently been approved for launch in 2025.

Resonant locking of two planets is an expected outcome of convergent disc migration. The planets subsequently migrate together as a resonant pair. In the context of circumbinary planets, the disc is truncated internally by the binary. If there were only a single planet, then this inner disc edge would provide a natural parking location. However, for two planets migrating together in resonance there will be a tension between the inner planet stopping at the disc edge, and the outer planet continuing to be torqued inwards. In this paper we study this effect, showing that the outcome is a function of the planet-planet mass ratio. Smaller outer planets tend to be parked in a stable exterior 2:1 or 3:2 resonance with the inner planet, which itself remains near the disc edge. Equal or larger mass outer planets tend to push the inner planet past the disc edge and too close to the binary, causing it to be ejected or sometimes flipped to an exterior orbit. Our simulations show that this process may explain an observed dearth of small (< 3 Earth radii) circumbinary planets, since small planets are frequently ejected or left on long-period orbits, for which transit detection is less likely. This may also be an efficient mechanism for producing free-floating planets and interstellar interlopers like `Oumuamua.

Relativistic electrons and magnetic fields permeate the intra-cluster medium (ICM) and manifest themselves as diffuse sources of synchrotron emission observable at radio wavelengths, namely radio halos and radio relics. Although there is broad consensus that the formation of these sources is connected to turbulence and shocks in the ICM, the details of the required particle acceleration, the strength and morphology of the magnetic field in the cluster volume, and the influence of other sources of high-energy particles are poorly known. Sufficiently large samples of radio halos and relics, which would allow us to examine the variation among the source population and pinpoint their commonalities and differences, are still missing. At present, large numbers of these sources are easiest to detect at low radio frequencies, where they shine brightly. We examined the low-frequency radio emission from all 309 clusters in the second catalog of Planck Sunyaev Zel'dovich detected sources that lie within the 5634 deg$^2$ covered by the Second Data Release of the LOFAR Two-meter Sky Survey (LoTSS-DR2). We produced LOFAR images at different resolutions, with and without discrete sources subtracted, and created overlays with optical and X-ray images before classifying the diffuse sources in the ICM, guided by a decision tree. Overall, we found 83 clusters that host a radio halo and 26 that host one or more radio relics (including candidates). About half of them are new discoveries. The detection rate of clusters hosting a radio halo and one or more relics in our sample is $30\pm11$% and $10\pm6$%, respectively. Extrapolating these numbers, we anticipate that once LoTSS covers the entire northern sky it will provide the detection of $251\pm92$ clusters hosting a halo and $83\pm50$ clusters hosting at least one relic from Planck clusters alone.

The Event Horizon Telescope (EHT) has released analyses of reconstructed images of horizon-scale millimeter emission near the supermassive black hole at the center of the M87 galaxy. Parts of the analyses made use of a large library of synthetic black hole images and spectra, which were produced using numerical general relativistic magnetohydrodynamics fluid simulations and polarized ray tracing. In this article, we describe the PATOKA pipeline, which was used to generate the Illinois contribution to the EHT simulation library. We begin by describing the relevant accretion systems and radiative processes. We then describe the details of the three numerical codes we use, iharm, ipole, and igrmonty, paying particular attention to differences between the current generation of the codes and the originally published versions. Finally, we provide a brief overview of simulated data as produced by PATOKA and conclude with a discussion of limitations and future directions for such simulation pipelines.

We present the first comprehensive search for high-energy neutrino emission from high- and low-mass X-ray binaries conducted by IceCube. Galactic X-ray binaries are long-standing candidates for the source of Galactic hadronic cosmic rays and neutrinos. The compact object in these systems can be the site of cosmic-ray acceleration, and neutrinos can be produced by interactions of cosmic rays with radiation or gas, in the jet of a microquasar, in the stellar wind, or in the atmosphere of the companion star. We study X-ray binaries using 7.5 years of IceCube data with three separate analyses. In the first, we search for periodic neutrino emission from 55 binaries in the Northern Sky with known orbital periods. In the second, the X-ray light curves of 102 binaries across the entire sky are used as templates to search for time-dependent neutrino emission. Finally, we search for time-integrated emission of neutrinos for a list of 4 notable binaries identified as microquasars. In the absence of a significant excess, we place upper limits on the neutrino flux for each hypothesis and compare our results with theoretical predictions for several binaries. In addition, we evaluate the sensitivity of the next generation neutrino telescope at the South Pole, IceCube-Gen2, and demonstrate its power to identify potential neutrino emission from these binary sources in the Galaxy.

There is now ample evidence that dust is already present in abundance at high z. However, given the faintness of distant galaxies in the optical and the NIR, datasets are still limited and how the dust affects the emerging radiation of galaxies at very high redshift is not yet fully understood. Using the ALPINE survey, our objective is to quantify the dust attenuation properties in galaxies at z=4.4-5.5, and in particular the shape of their attenuation curve. Using the CIGALE code, we model the stellar populations and their interaction with the dust in order to measure some of the physical properties of a subsample of 23 main-sequence ALPINE galaxies. We find that the attenuation curves span a broad range of properties, from curves that are much steeper than the SMC extinction curve, to shallower than the starburst attenuation curve. The shape of the attenuation curves strongly depends on the V-band attenuation. Galaxies with the lowest attenuation also present the steepest curves. The steepness of such curves is probably the consequence of the combination of the intrinsic physical properties of the dust, the relative distribution of stars and dust in the interstellar medium, and the differential reddening. The broad range of attenuation curves found at z~5 shows that no single attenuation curve is appropriate for main sequence galaxies and that assuming a fixed curve can lead to large errors, for instance in the interpretation and use of the IRX-beta diagram, if SED modeling is not feasible. Great caution should be exercised when correcting high redshift galaxies for the presence of dust using the UV slope beta as it can affect the estimation of both SFR and stellar mass even at low V-band attenuation due to the steepness of the attenuation curve. However, when SED modeling can be used, the impact of the choice of the attenuation curve on the SFR and the stellar mass is limited.

Upcoming cosmic microwave background (CMB) lensing measurements and tomographic galaxy surveys are expected to provide us with high-precision data sets in the coming years, thus paving the way for fruitful cross-correlation analyses. In this paper we study the information content of the weighted skew-spectrum, a nearly-optimal estimator of the angular bispectrum amplitude, as a means to extract non-Gaussian information on both bias and cosmological parameters from the bispectra of galaxies cross-correlated with CMB lensing, while gaining significantly on speed. Our results suggest that for the combination of Planck satellite and the Dark Energy Spectroscopic Instrument (DESI), the skew-spectrum achieves almost equivalent information for both bias and cosmological parameters as the bispectrum, where the difference in the constraints is at most $17\%$. We further compare and find agreement between our theoretical skew-spectra and those estimated from N-body simulations, and show that it is crucial to include gravitational non-linearities beyond perturbation theory and the post-Born effect for CMB lensing. We define an algorithm to apply the skew-spectrum estimator to the data and, as a preliminary step, we use the skew-spectra to constrain bias parameters and the amplitude of shot noise from the simulations through a Markov chain Monte Carlo likelihood analysis, finding that it may be possible to reach percent-level estimates for the linear bias parameter $b_1$.

Planet induced sub-structures, like annular gaps, observed in dust emission from protoplanetary disks provide a unique probe to characterize unseen young planets. While deep learning based model has an edge in characterizing the planet's properties over traditional methods, like customized simulations and empirical relations, it lacks in its ability to quantify the uncertainty associated with its predictions. In this paper, we introduce a Bayesian deep learning network "DPNNet-Bayesian" that can predict planet mass from disk gaps and provides uncertainties associated with the prediction. A unique feature of our approach is that it can distinguish between the uncertainty associated with the deep learning architecture and uncertainty inherent in the input data due to measurement noise. The model is trained on a data set generated from disk-planet simulations using the \textsc{fargo3d} hydrodynamics code with a newly implemented fixed grain size module and improved initial conditions. The Bayesian framework enables estimating a gauge/confidence interval over the validity of the prediction when applied to unknown observations. As a proof-of-concept, we apply DPNNet-Bayesian to dust gaps observed in HL Tau. The network predicts masses of $ 86.0 \pm 5.5 M_{\Earth} $, $ 43.8 \pm 3.3 M_{\Earth} $, and $ 92.2 \pm 5.1 M_{\Earth} $ respectively, which are comparable to other studies based on specialized simulations.

In this data release from the LOFAR Two-metre Sky Survey (LoTSS) we present 120-168MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m +44$^\circ$30' and 1h00m +28$^\circ$00' and spanning 4178 and 1457 square degrees respectively. The images were derived from 3,451hrs (7.6PB) of LOFAR High Band Antenna data which were corrected for the direction-independent instrumental properties as well as direction-dependent ionospheric distortions during extensive, but fully automated, data processing. A catalogue of 4,396,228 radio sources is derived from our total intensity (Stokes I) maps, where the majority of these have never been detected at radio wavelengths before. At 6" resolution, our full bandwidth Stokes I continuum maps with a central frequency of 144MHz have: a median rms sensitivity of 83$\mu$Jy/beam; a flux density scale accuracy of approximately 10%; an astrometric accuracy of 0.2"; and we estimate the point-source completeness to be 90% at a peak brightness of 0.8mJy/beam. By creating three 16MHz bandwidth images across the band we are able to measure the in-band spectral index of many sources, albeit with an error on the derived spectral index of +/-0.2 which is a consequence of our flux-density scale accuracy and small fractional bandwidth. Our circular polarisation (Stokes V) 20" resolution 120-168MHz continuum images have a median rms sensitivity of 95$\mu$Jy/beam, and we estimate a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation (Stokes Q and Stokes U) image cubes consist of 480 x 97.6 kHz wide planes and have a median rms sensitivity per plane of 10.8mJy/beam at 4' and 2.2mJy/beam at 20"; we estimate the Stokes I to Stokes Q/U leakage to be approximately 0.2%. Here we characterise and publicly release our Stokes I, Q, U and V images in addition to the calibrated uv-data.

Using Large Binocular Telescope deep imaging data from the Smallest Scale of Hierarchy Survey (SSH) and archival Hubble Space Telescope data, we reveal the presence of two elongated stellar features contiguous to a bar-like stellar structure in the inner regions of the dwarf irregular galaxy NGC 3741. These structures are dominated by stars younger than a few hundred Myr and collectively are about twice as extended as the old stellar component. These properties are very unusual for dwarf galaxies in the nearby Universe and difficult to explain by hydro-dynamical simulations. From the analysis of archival 21-cm observations, we find that the young stellar "bar" coincides with an HI high-density region proposed by previous studies to be a purely gaseous bar; we furthermore confirm radial motions of a few km/s, compatible with an inflow/outflow, and derive a steeply-rising rotation curve and high HI surface density at the center, indicating a very concentrated mass distribution. We propose that the peculiar properties of the stellar and gaseous components of NGC 3741 may be explained by a recent merger or ongoing gas accretion from the intergalactic medium, which caused gas inflows towards the galaxy center and triggered star formation a few hundred Myr ago. This event may explain the young and extended stellar features, the bar-like structure, the very extended HI disc and the central HI spiral arms. The high central HI density and the steeply rising rotation curve suggest that NGC 3741 may be the progenitor or the descendant of a starburst dwarf.

The spin-orbit misalignments of stellar-mass black hole binaries (BHB) provide important constraints on the formation channels of merging BHBs. Here, we study the spin evolution of a black-hole component in a BHB around a supermassive BH (SMBH) in an AGN disk. We consider the BH's spin-precession due to the $J_2$ moment introduced by a circum-BH disk within the warping/breaking radius of the disk. We find that the BH's spin-orbit misalignment (obliquity) can be excited via spin-orbit resonance between the BHB's orbital nodal precession and the BH spin-precession driven by the circum-BH disk. Assuming a $10^7$M$_{\odot}$ SMBH, this typically occurs at a distance of $10^{2-4}$AU to the SMBH or $10^{3-5} GM_{\rm SMBH}/c^2$. In many cases, spin-orbit resonance leads to a high BH obliquity, and a broad distribution of the binary components' obliquities and effective spin parameters.

We present optical spectroscopic and milli-arcsecond scale radio continuum observations of the quasar M1540-1453 ($z_{em}$ = 2.104$\pm$0.002) that shows associated HI 21-cm absorption at $z_{abs}$ = 2.1139. At sub-kpc scales, the powerful radio source with 1.4 GHz luminosity of $5.9\times10^{27}$ WHz$^{-1}$ shows Fanaroff-Riley (FR) class I morphology caused by the interaction with dense gas within 70 pc from the AGN. Interestingly, while there are indications for the presence of absorption from low-ionization species like FeII, SiII and SiIII in the optical spectrum, the expected strong damped Ly$\alpha$ absorption is not detected at the redshift of the HI 21-cm absorber. In comparison to typical high-$z$ quasars, the Ly$\alpha$ emission line is much narrower. The `ghostly' nature of the HI Ly$\alpha$ absorber partially covering the broad line region of extent 0.05 pc and the detection of widespread HI 21-cm absorption covering the diffuse radio source (extent $>$425 pc) imply the presence of a large clumpy HI halo -- which may have been blown by the jet-ISM interaction. Further observations are needed to confirm the `ghostly' nature of the Ly$\alpha$ absorber, and obtain a better understanding of the role played by the jet-ISM interaction in shaping the radio morphology of this powerful AGN. The study showcases how joint radio and optical analysis can shed light on gaseous environment and origin of radio morphology in AGN at high redshifts, when these are still the assembly sites of giant galaxies.

In this paper we report spectroscopy of the transiting hot Jupiter HAT-P-1b. The HAT-P-1b is a giant ($R = 1.2 RJ$), low-mean density transiting extrasolar planet in a visual binary system, composed of two sun-like stars. The host star HAT-P-1b known as ADS 16402 B is a G0V C dwarf (V = 9.87). We revealed optical emission of $C_{2}$, $CN$ and $CH$ radicals in the spectrum of the hot Jupiter HAT-P-1b. We discovered radial pulsation of the hot Jupiter HAT-P-1b with a period of about 1900 sec.

2MASS J20395358+4222505 is an obscured early B supergiant near the massive OB star association Cyg OB2. Despite its bright infrared magnitude (K$_{s}$=5.82) it has remained largely ignored because of its dim optical magnitude (B=16.63, V=13.68). In a previous paper we classified it as a highly reddened, potentially extremely luminous, early B-type supergiant. We obtained its spectrum in the U, B and R spectral bands during commissioning observations with the instrument MEGARA@GTC. It displays a particularly strong H$\alpha$ emission for its spectral type, B1 Ia. The star seems to be in an intermediate phase between super- and hypergiant, a group that it will probably join in the near (astronomical) future. We observe a radial velocity difference between individual observations and determine the stellar parameters, obtaining T$_{eff}$ = 24000 K, logg$_{c}$= 2.88 $\pm$ 0.15. The rotational velocity found is large for a B-supergiant, vsini= 110 $\pm$ 25 km s$^{-1}$. The abundance pattern is consistent with solar, with a mild C underabundance (based on a single line). Assuming that J20395358+4222505 is at the distance of Cyg OB2 we derive the radius from infrared photometry, finding R= 41.2 $\pm$ 4.0 R$_{\odot}$, log(L/L$_{\odot}$)= 5.71 $\pm$ 0.04 and a spectroscopic mass of 46.5 $\pm$ 15.0 M$_{\odot}$. The clumped mass-loss rate (clumping factor 10) is very high for the spectral type, $\dot{M}$ = 2.4x10$^{-6}$ M$_{\odot}$ a$^{-1}$. The high rotational velocity and mass-loss rate place the star at the hot side of the bi-stability jump. Together with the nearly solar CNO abundance pattern, they may also point to evolution in a binary system, J20395358+4222505 being the initial secondary.

We made a time-resolved photometric campaign of the bright cataclysmic variable ASAS J071404+7004.3 in 2020. Inight et al. (2022, arXiv/2109.14514) recently published time-resolved optical spectroscopy, X-ray observations and long- and short-term optical variations. Although their results were correct in many parts, they classified ASAS J071404+7004.3 as a VY Scl-type novalike object. By comparing the ASAS-SN data of this object and the IW And-type object HO Pup, we showed that their type classification was incorrect. ASAS J071404+7004.3 showed outbursts from a standstill followed by shallow dips, which is the defining characteristic of an IW And star. This object predominantly showed states with low-amplitude dwarf nova-type oscillations, some of which could be identified as the "heartbeat"-type state as a variety of the IW And-type phenomenon. The low state described by Inight et al. (2022) was not a true low state of a VY Scl star, but a dwarf nova-type state with increased outburst amplitudes. Both ground-based (our campaign) and TESS observations detected orbital variations whose periods [0.136589(5) d by the ground-based campaign and 0.1366476(3) d by the TESS data] are in very good agreement with the one obtained by radial-velocity studies by Inight et al. (2022). The standstill in 2019-2020 in ASAS J071404+7004.3 was not brighter than its dwarf nova-type states. The brightest moment of this object occurred when the amplitudes of dwarf nova-type variations were large, which challenges the widely accepted interpretation that standstills in Z Cam stars occur when the mass-transfer rates are high.

Rank-2 tensor fields of large-scale structure, e.g. a tensor field inferred from shapes of galaxies, open up a window to directly access 2 scalar, 2 vector and 2 tensor modes, where the scalar fields can be measured independently from the standard density field that is traced by distribution of galaxies. Here we develop an estimator of the multipole moments of coordinate-independent power spectra for the three-dimensional tensor field, taking into account the projection of the tensor field onto plane perpendicular to the line-of-sight direction. To do this, we find that a convenient representation of the power spectrum multipoles can be obtained by the use of the associated Legendre polynomials in the form which allows for the fast Fourier transform estimations under the local plane-parallel (LPP) approximation. The formulation also allows us to obtain the Hankel transforms to connect the two-point statistics in Fourier and configuration space, which are needed to derive theoretical templates of the power spectrum including convolution of a survey window. To validate our estimators, we use the simulation data of the projected tidal field assuming a survey window that mimics the BOSS-like survey footprint. We show that the LPP estimators fairly well recover the multipole moments that are inferred from the global plane-parallel approximation. We find that the survey window causes a more significant change in the multipole moments of projected tensor power spectrum at $k\lesssim 0.1\,h{\rm Mpc}^{-1}$ from the input power spectrum, than in the density power spectrum. Nevertheless, the theoretical predictions including the survey window effects match the multipole moments measured from the simulations. The analysis method presented here paves the way for a cosmological analysis using three-dimensional tensor-type tracers of large-scale structure for current and future surveys.

The coma of comet C/2016 R2 (PanSTARRS) is one of the most chemically peculiar ever observed, in particular due to its extremely high CO/H2O and N2+/H2O ratios}, and unusual trace volatile abundances. However, the complex shape of its CO emission lines, as well as uncertainties in the coma structure and excitation, has lead to ambiguities in the total CO production rate. We performed high resolution, spatially, spectrally and temporally resolved CO observations using the James Clerk Maxwell Telescope (JCMT) and Submillimeter Array (SMA) to elucidate the outgassing behaviour of C/2016 R2. Results are analyzed using a new, time-dependent, three dimensional radiative transfer code (SUBLIME), incorporating for the first time, accurate state-to-state collisional rate coefficients for the CO--CO system. The total CO production rate was found to be in the range $(3.8-7.6)\times10^{28}$ s$^{-1}$ between 2018-01-13 and 2018-02-01, with a mean value of $(5.3\pm0.6)\times10^{28}$ s$^{-1}$ at r_H = 2.8-2.9 au. The emission is concentrated in a near-sunward jet, with an outflow velocity $0.51\pm0.01$ km/s, compared to $0.25\pm0.01$ km/s in the ambient (and night-side) coma. Evidence was also found for an extended source of CO emission, possibly due to icy grain sublimation around $1.2\times10^5$ km from the nucleus. Based on the coma molecular abundances, we propose that the nucleus ices of C/2016 R2 can be divided into a rapidly sublimating apolar phase, rich in CO, CO2, N2 and CH3OH, and a predominantly frozen (or less abundant), polar phase containing more H2O, CH4, H2CO and HCN.

There is a strong discrepancy between the value of the Hubble parameter $H_0^P$ obtained from large scale observations such as the Planck mission, and the small scale value $H_0^R$, obtained from low redshift supernovae (SNe). The value of the absolute magnitude $M^{hom}$ used as prior in analyzing observational data is obtained from low-redshift SNe, assuming a homogeneous Universe, but the distance of the anchors used to calibrate the SNe to obtain $M$ would be affected by a local inhomogeneity, making it inconsistent to test the Copernican principle using $M^{hom}$, since $M$ estimation itself is affected by local inhomogeneities. We perform an analysis of the luminosity distance of low redshift SNe, using different values of $M$, $\{M^P,M^R\}$, corresponding to different values of $H_0$, $\{H_0^P,H_0^R\}$, obtained from the model independent consistency relation between $H_0$ and $M$ which can be derived from the definition of the distance modulus. We find that the value of $M$ can strongly affect the evidence of a local inhomogeneity. We analyze data from the Pantheon catalog, finding no significant statistical evidence of a local inhomogeneity using the parameters $\{M^R,H_0^R\}$, confirming previous studies, while with $\{M^P,H_0^P\}$ we find evidence of a small local void, which cause an overestimation of $M^R$ with respect to $M^P$. An inhomogeneous model with the parameters $\{M^P,H_0^P\}$ fits the data better then a homogeneous model with $\{M^R,H_0^R\}$, resolving the apparent $H_0$ tension. Using $\{M^P,H_0^P\}$, we obtain evidence of a local inhomogeneity with a density contrast $-0.140 \pm 0.042 $, extending up to a redshift of $z_v =0.056 \pm 0.0002$, in good agreement with recent results of galaxy catalogs analysis.

Gravitationally lensed sources may have unresolved or blended multiple images, and for time varying sources the lightcurves from individual images can overlap. We use convolutional neural nets to both classify the lightcurves as due to unlensed, double, or quad lensed sources and fit for the time delays. Focusing on lensed supernova systems with time delays $\Delta t\gtrsim6$ days, we achieve 100\% precision and recall in identifying the number of images and then estimating the time delays to $\sigma_{\Delta t}\approx1$ day, with a $1000\times$ speedup relative to our previous Monte Carlo technique. This also succeeds for flux noise levels $\sim10\%$. For $\Delta t\in[2,6]$ days we obtain 94--98\% accuracy, depending on image configuration. We also explore using partial lightcurves where observations only start near maximum light, without the rise time data, and quantify the success.

We present a series of numerical solutions of spherically symmetric stationary flows with nuclear burning accreted by a neutron star (or black hole). We consider the accretion of matter composed of carbon and oxygen, which mimics the flow after a neutron star is engulfed by a CO star or CO core of a massive star. It is found that there are two types of transonic solutions depending on the accretion rate. The flow with a small accretion rate reaches the center (or the surface of the central object) at supersonic speeds. The other type with a large accretion rate has another sonic point inside the transonic point and the flow truncates at the sonic point. The critical accretion rate dividing these two types is derived as a function of the mass of the central object and the specific enthalpy in the ambient matter. We discuss implications from the solutions for a new mechanism of super-Chandrasekhar type Ia supernovae and type Icn supernovae.

Some of the major challenges faced in understanding the early evolution of Coronal Mass Ejections (CMEs) are due to limited observations in the inner corona ($<\,3$ R$_{\odot}$) and the plane of sky measurements. In this work, we have thus extended the application of the Graduated Cylindrical Shell (GCS) model to the inner coronal observations from the ground--based coronagraph K--Cor of the Mauna Loa Solar Observatory (MLSO) along with the pair of observations from COR--1 onboard the Solar Terrestrial Relations Observatory (STEREO). We study the rapid initial acceleration and width expansion phase of 5 CMEs in white-light in the lower heights. We also study the evolution of the modelled volume of these CMEs in inner corona and report for the first time, a power law dependence of the CME volume with distance from the Sun. We further find the volume of ellipsoidal leading front and the conical legs follow different power laws, thus indicating differential volume expansion through a CME. The study also reveals two distinct power laws for the total volume evolution of CMEs in the inner and outer corona, thus suggesting different expansion mechanisms at these different heights. These results besides aiding our current understanding on CME evolution, will also provide better constraints to CME initiation and propagation models. Also, since the loss of STEREO-B (and hence COR--1B data) from 2016, this modified GCS model presented here will still enable stereoscopy in the inner corona for the 3D study of CMEs in white-light.

We investigate the formation and morphological evolution of the first galaxies in the cosmic morning ($10>z>4$) using the Horizon Run 5 (HR5) cosmological hydrodynamical simulation. For galaxies above the stellar mass $M_{\star} = 2\times10^9\,M_{\odot}$, we classify them into disk, spheroid, and irregular types according to their asymmetry and stellar mass morphology. We find that 2/3 of galaxies have a S\'{e}rsic index less than 1.5, reflecting the dominance of disk-type morphology in the cosmic morning. The rest are evenly distributed as irregulars or spheroids. We also find that these fractions are roughly independent of redshift and stellar mass up to $\sim10^{10}\,M_{\odot}$, while irregular or spheroidal morphology appears incidental and transient. Almost all the first galaxies with $M_{\star}>2\times10^9\,M_{\odot}$ at redshift 6 form at initial peaks of the matter density field. Large-scale structures in the universe emerge and grow like cosmic rhizomes as the underlying matter density fluctuations grow and form associations of galaxies in rare overdense regions. The growth of the density field further stretches the realm of the galactic world into relatively lower-density regions along evolving filaments. The cosmic web of galaxies forms at lower redshifts when most rhizomes globally percolate. The primordial angular momentum produced by the induced tidal torques on protogalactic regions is correlated with the internal kinematics of galaxies and tightly aligned with the angular momentum of the total galaxy mass. However, the primordial angular momentum only very weakly correlates with the instantaneous morphology and orientation of the stellar component below $z=6$. The large-scale tidal field imprinted in the initial conditions seems responsible for the dominance of disk morphology, and for the tendency of galaxies to re-acquire a disk post-distortion.

Depending on the stellar densities, protoplanetary discs in stellar clusters undergo back-ground heating, stellar encounters, disc truncation and photo-evaporation. Disc truncation leads to reduced characteristic sizes and disc masses that eventually halts gas giant planet formation. We investigate how disc truncation impacts planet formation via pebble-based core accretion paradigm, where pebble sizes were derived from the full grain-size distribution within the disc lifetimes. We make the best-case assumption of one embryo and one stellar encounter per disc. Using planet population syntheses techniques, we find that disc truncation shifts the disc mass distributions to the lower margins. This consequently lowered the gas giant occurrence rates. Despite the reduced gas giant formation rates in clustered discs, the encounter models show as in the isolated field; the cold Jupiters are more frequent than the hot Jupiters, consistent with observation. Moreover, the ratio of hot to cold Jupiters depend on the periastron distribution of the perturbers with linear distribution in periastron ratio showing enhanced hot to cold Jupiters ratio in comparison to the remaining models. Our results are valid in the best-case scenario corresponding to our assumptions of: only one disc encounter with a perturber, ambient background heating and less rampant photo-evaporation. It is not known exactly of how much gas giant planet formation would be affected should disc encounter, background heating and photo-evaporation act in a concert. Thus, our study will hopefully serve as motivation for quantitative investigations of the detailed impact of stellar cluster environments on planet formations.

Morphological and chemical structures of M33 are investigated with LAMOST DR7 survey. Physical parameters, extinction, chemical composition of He, N, O, Ne, S, Cl, Ar (where available), and radial velocities were determined for 110 nebulae (95 H\ii\ regions and 15 PNe) in M33. Among them, 8 PNe and 55 H\ii\ regions in M33 are newly discovered. We obtained the following O abundance gradients: $-$0.199$_{-0.030}^{+0.030}$ dex $R_{25}^{-1}$ (based on 95 H\ii\ regions), $-$0.124$_{-0.036}^{+0.036}$ dex $R_{25}^{-1}$ (based on 93 H\ii\ regions), and $-$0.207$_{-0.174}^{+0.160}$ dex $R_{25}^{-1}$ (based on 21 H\ii\ region), utilizing abundances from N2 at O3N2 diagnostics and the $T_{\rm e}$-sensitive method, respectively. The He, N, Ne, S, and Ar gradients resulted in slopes of $-$0.179$_{-0.146}^{+0.145}$, $-$0.431$_{-0.281}^{+0.282}$, $-$0.171$_{-0.239}^{+0.234}$, $-$0.417$_{-0.182}^{+0.174}$, $-$0.340$_{-0.157}^{+0.156}$, respectively, utilizing abundances from the $T_{\rm e}$-sensitive method. Our results confirm the existence of negative axisymmetric global metallicity distribution that is assumed in the literature. We noticed one new WC star candidate and one transition WR WN/C candidate. The grand-design pattern of spiral structure of M33 is presented.

Radio galaxies are promising candidates as the sources of ultrahigh energy cosmic rays (UHECRs). In this work, we examine if the stringent constraints imposed by the dipole and quadropole anisotropies as well as the UHECR spectrum and composition allow that radio galaxies are the dominant extragalactic cosmic ray sources. In order to calculate the UHECR flux emitted by individual radio galaxies, we constrain their properties using information from the radio-CR correlation and a dynamical evolution model. In addition to the UHECR flux from individual, local sources, we include the diffuse flux emitted by the bulk of non-local radio galaxies based on their radio luminosity distribution. Analyzing the source parameters within a range around their expected properties, we finally determine the configurations of local sources describing well the UHECR spectrum, composition and large-scale anisotropies. We obtain a good description of all data even in the case that we include only a small number of local sources. In particular, we find that scenarios where few sources like Fornax A and Virgo A dominate the flux above the ankle, while low-luminosity radio galaxies contribute an isotropic background dominating below the ankle, provide a good fit to the data.

The Multi-conjugate Adaptive Optics RelaY (MAORY) is one of the key Adaptive Optics (AO) systems on the European Southern Observatory's Extremely Large Telescope. MAORY aims to achieve a good wavefront correction over a large field of view, which involves a tomographic estimation of the 3D atmospheric wavefront disturbance. Mathematically, the reconstruction of turbulent layers in the atmosphere is severely ill-posed, hence, limits the achievable reconstruction accuracy. Moreover, the reconstruction has to be performed in real-time at a few hundred to one thousand Hertz frame rates. Huge amounts of data have to be processed and thousands of actuators of the deformable mirrors have to be controlled by elaborated algorithms. Even with extensive parallelization and pipelining, direct solvers, such as the Matrix Vector Multiplication (MVM) method, are extremely demanding. Thus, research in the last years shifted into the direction of iterative methods. In this paper we focus on the iterative Finite Element Wavelet Hybrid Algorithm (FEWHA). The key feature of FEWHA is a matrix-free representation of all operators involved, which makes the algorithm fast and enables on the fly system updates whenever parameters at the telescope or in the atmosphere change. We provide a performance analysis of the method regarding quality and run-time for the MAORY instrument using the AO software package COMPASS.

In this work, we propose new statistical tools that are capable of characterizing the simultaneous dependence of the matter clustering on the scale and density environment, which are the environment-dependent wavelet power spectrum (env-WPS) and environment-dependent wavelet cross-correlation (env-WCC). We apply these statistics to the projected 2D dark matter and baryonic gas density fields of the IllustrisTNG simulation at redshifts from $z=3.0$ to $z=0.0$. Measurement of the env-WPSs indicates that the clustering strengths of both the dark matter and gas increase with density. At all redshifts, we observe that the env-WPS of the gas is suppressed on intermediate and small scales, which is caused by baryonic processes. Furthermore, by computing the environmental bias function, we find that this suppression varies with the environment, scale and redshift. A noteworthy feature is that at $z=0.0$, the bias value increases with density on scales $2\lesssim k \lesssim 10 \ h\mathrm{Mpc}^{-1}$, which is the reversal of that in earlier times. On the other hand, the env-WCC also shows strong environmental dependence on scales $k \gtrsim 2 \ h\mathrm{Mpc}^{-1}$ and is sensitive to the redshift. We find that at $z=3.0$, the coherence of the dark matter and gas decreases with density. At lower redshifts, the coherence in denser environments becomes much higher than that in less dense environments. These results suggest that baryonic processes have less effect on the matter clustering in high-density environments at later times. Obviously, these statistics provide us rich information and hence could improve our understanding of the matter clustering.

Close-in giant planets with strong stellar irradiation show atmospheric circulation patterns with strong equatorial jets and global-scale stationary waves. So far, almost all modeling works on atmospheric circulations of such giant planets have mainly considered external radiation alone, without taking into account the role of internal heat fluxes or just treating it in very simplified ways. Here, we study atmospheric circulations of strongly irradiated giant planets by considering the effect of internal forcing, which is characterized by small-scale stochastic interior thermal perturbations, using a three-dimensional atmospheric general circulation model. We show that the perturbation-excited waves can largely modify atmospheric circulation patterns in the presence of relatively strong internal forcing. Specifically, our simulations demonstrate three circulation regimes: superrotation regime, midlatitude-jet regime, and quasi-periodic oscillation regime, depending on the relative importance of external and internal forcings. It is also found that strong internal forcing can cause noticeable modifications of the thermal phase curves.

Uninterrupted observations from space-borne telescopes provide the photometric precision that is required to detect shallow transits of small planets missed by ground-based surveys. We used data from the Transiting Exoplanet Survey Satellite (TESS) to search for nearby planetary companions in 12 planetary systems with hot Jupiters: HD 2685, Qatar-10, WASP-4, WASP-48, WASP-58, WASP-91, WASP-120, WASP-121, WASP-122, WASP-140, XO-6, and XO-7. We also applied the transit timing method based on homogeneously determined mid-transit times in order to search for non-transiting companions that could gravitationally perturb the already known planets. We found no additional planets in those systems down to the regime of sub-Neptunian globes. This negative result is in line with statistical studies, supporting the high-eccentricity migration as a pathway of the investigated giant planets to the tight orbits observed today.

Direct imaging and spectroscopy of Earth-like planets and young Jupiters require contrasts up to 10^6-10^10 at angular separations of a few dozen milliarcseconds. To achieve this goal, one of the most promising approaches consists of using large segmented primary mirror telescopes with coronagraphic instruments. However, coronagraphs are highly sensitive to wavefront errors. The segmentation itself is responsible for phasing errors and segment vibrations to be controlled at a subnanometric accuracy. We propose an innovative method for a coronagraph design that allows a consequent relaxation of the segment phasing constraints for low segment-count mirrors and generates an instrument that is more robust to segment-level wavefront errors. It is based on an optimization of the coronagraph that includes a segment-level apodization. This is repeated over the pupil to match the segmentation redundancy and improves the contrast stability beyond the minimum separation set by the single-segment diffraction limit. We validate this method on a GMT-like pupil for two coronagraph types: apodized pupil Lyot coronagraphs (APLC) and apodizing phase plate coronagraphs (APP). For the APLC, redundant apodization enables releasing the piston phasing constraints by a factor of 5 to 20 compared to classical designs. For the APP, the contrast remains almost constant up to 1 radian RMS of the phasing errors. We also show that redundant apodizations increase the robustness of the coronagraph to segment tip-tilt errors, as well as to missing segments. This method cannot be applied to higher-segment count mirrors such as the ELT or the TMT, but it is particularly suitable for low segment-count mirrors (fewer than 20 segments) such as the GMT aperture. These mirrors aim for high-contrast imaging of debris disks or exoplanets down to 100 mas.

In this manuscript, a 6.4yr optical quasi-periodic oscillations (QPOs) is detected in the quasar SDSS J075217.84+193542.2 (=\obj) at a redshift 0.117, of which 13.6yr-long light curve from CSS and ASAS-SN directly described by a sinusoidal function with a periodicity 6.4yr. The 6.4yr QPOs can be further confirmed through the Generalized Lomb-Scargle periodogram with confidence level higher than 99.99\%, and through the auto-correlation analysis results, and through the WWZ technique. The optical QPOs strongly indicate a central binary black hole (BBH) system in \obj. The determined two broad Gaussian components in the broad H$\alpha$ can lead to the BBH system with expected space separation about 0.02pc between the expected two central BHs with determined virial BH masses about $8.8\times10^7{\rm M_\odot}$ and $1.04\times10^9{\rm M_\odot}$. Meanwhile, we check the disk precessions applied to explain the optical QPOs. However, under the disk precession assumption, the determined optical emission regions from central BH have sizes about $40{\rm R_G}$ two times smaller than sizes of the expected NUV emission regions through the correlation between disk size and BH mass, indicating the disk precessions are not preferred. And due to the lower radio loudness around 0.28, jet precessions can be also totally ruled out. Furthermore, only 0.08\% probability can determined as the QPOs mis-detected through light curves randomly created by the CAR process, re-confirming the reported optical QPOs.

Understanding convection in red supergiants and the mechanisms that trigger the mass loss from these evolved stars are the general goals of most observations of Betelgeuse and its inner circumstellar environment. Linear spectropolarimetry of the atomic lines of the spectrum of Betelgeuse reveals information about the three-dimensional (3D) distribution of brightness in its atmosphere. We model the distribution of plasma and its velocities and use inversion algorithms to fit the observed linear polarization. We obtain the first 3D images of the photosphere of Betelgeuse. Within the limits of the used approximations, we recover vertical convective flows and measure the velocity of the rising plasma at different heights in the photosphere. In several cases, we find this velocity to be constant with height, indicating the presence of forces other than gravity acting on the plasma and counteracting it. In some cases, these forces are sufficient to maintain plasma rising at 60\,\kms to heights where this velocity is comparable to the escape velocity. Forces are present in the photosphere of Betelgeuse that allow plasma to reach velocities close to the escape velocity. These mechanisms may suffice to trigger mass loss and sustain the observed large stellar winds of these evolved stars.

The use of 3D hydrodynamical simulations of stellar surface convection for model atmospheres is computationally expensive. Although these models have been available for quite some time, their use is limited because of the lack of extensive grids of simulations and associated spectra. Our goal is to provide a method to interpolate spectra that can be applied to both 1D and 3D models, and implement it in a code available to the community. This tool will enable the routine use of 3D model atmospheres in the analysis of stellar spectra.} We have developed a code that makes use of radial basis functions to interpolate the spectra included in the CIFIST grid of 84 three-dimensional model atmospheres. Spectral synthesis on the hydrodynamical simulations was previously performed with the code ASS$\epsilon$T. We make a tool for the interpolation of 3D spectra available to the community. The code provides interpolated spectra and interpolation errors for a given wavelength interval, and a combination of effective temperature, surface gravity, and metallicity. In addition, it optionally provides graphical representations of the RMS and mean ratio between 1D and 3D spectra, and maps of the errors in the interpolated spectra across the parameter space.

To date, the presence of dark matter (DM) can be judged only by its gravitational interaction on the visible matter. It is therefore important to find the consequences of this interaction, which can then help to determine both the DM properties and parameters and the dynamics and evolution of visible matter. The gravitational influence of dark matter on the stability of interstellar medium (ISM), the progenitor of stars and star clusters, was considered. An isothermal self-gravity gas was taken as a suitable model describing ISM, particles interacting only gravitationally were considered as DM. The results obtained by analytical methods show that even a small amount of fast DM particles significantly increases the stable radius of the gas cloud and the corresponding mass while a higher relative density of DM destabilizes the gas. It was shown that with typical parameters of ISM and DM, its presence increases the maximum stable mass of isothermal cloud by a factor of four and the radius by five.

Context. A crucial step in the numerical investigation of small-scale dynamos in the solar atmosphere consists of an accurate determination of the magnetic Prandtl number, Prm, stemming from radiative magneto-hydrodynamic (MHD) simulations. Aims. The aims are to provide a reliable methodology for estimating the effective Reynolds and magnetic Reynolds numbers, Re and Rem, and their ratio Prm=Rem/Re (the magnetic Prandlt number), that characterise MHD simulations and to categorise small-scale dynamo simulations in terms of these dimensionless parameters. Methods. The methodology proposed for computing Re and Rem is based on the method of projection on proper elements and it relies on a post-processing step carried out using higher order accurate numerical operators than the ones in the simulation code. A number of radiative MHD simulations with different effective viscosities and plasma resistivities were carried out with the CO5BOLD code, and the resulting growth rate of the magnetic energy and saturated magnetic field strengths were characterised in terms of Re and Rem. Results. Overall, the proposed methodology provides a solid estimate of the dissipation coefficients affecting the momentum and induction equations of MHD simulation codes, and consequently also a reliable evaluation of the magnetic Prandtl number characterising the numerical results. Additionally, it is found that small-scale dynamos are active and can amplify a small seed magnetic field up to significant values in CO5BOLD simulations with a grid spacing smaller than h=12 km, even at Prm=0.65. However, it is also evident that it is difficult to categorise dynamo simulations in terms of Prm alone, because it is not only important to estimate the amplitude of the dissipation coefficients, but also at which scales energy dissipation takes place.

This thesis by publication is devoted to the study of aspects of the early universe in the context of primordial black hole (PBH) physics. Firstly, we review the fundamentals of the early universe cosmology and we recap the basics of the PBHs physics. In particular, we propose a refinement in the determination of the PBH formation threshold, a fundamental quantity in PBH physics, in the context of a time-dependent equation-of-state parameter. Afterwards, we briefly present the theory of inflationary perturbations, which is the theoretical framework within which PBHs are studied in this thesis. Then, in the second part of the thesis, we review the core of the research conducted within my PhD, in which aspects of the early universe and the gravitational wave physics are combined with the physics of PBHs. Moreover, aspects of the PBH gravitational collapse process are studied in the presence of anisotropies. Specifically, we study PBHs produced from the preheating instability in the context of single-field inflation. Interestingly, we find that PBHs produced during preheating can potentially dominate the universe's content and drive reheating through their evaporation. Then, we focus on the scalar induced second-order stochastic gravitational wave background (SGWB) induced from Poisson energy density fluctuations of ultralight PBHs. By taking then into account gravitational wave backreaction effects we set model-independent constraints on the initial abundance of ultralight PBHs as a function of their mass. Afterwards, we study in a covariant way the anisotropic spherical gravitational collapse of PBHs during a radiation-dominated era in which one can compute the PBH formation threshold as a function of the anisotropy. Finally, we summarize our research results by discussing future prospects opened up as a result of the research work conducted within this thesis.

We investigate the abundance and distribution of metals in the high-redshift intergalactic medium and circum-galactic medium through the analysis of a sample of almost 600 SiIV absorption lines detected in high and intermediate resolution spectra of 147 quasars. The evolution of the number density of SiIV lines, the column density distribution function and the cosmic mass density are studied in the redshift interval 1.7 <= z <= 6.2 and for log N(SiIV) >= 12.5. All quantities show a rapid increase between z~6 and z< 5 and then an almost constant behaviour to z~2 in very good agreement with what is already observed for CIV absorption lines. The present results are challenging for numerical simulations: when simulations reproduce our SiIV results, they tend to underpredict the properties of CIV, and when the properties of CIV are reproduced, the number of strong SiIV lines (log N(SiIV) > 14) is overpredicted.

The Hubble tension seems to be a crisis with $\sim5\sigma$ discrepancy between the most recent local distance ladder measurement from Type Ia supernovae calibrated by Cepheids and the global fitting constraint from the cosmic microwave background data. To narrow down the possible late-time solutions to the Hubble tension, we have used in a recent study [Phys. Rev. D 105 (2022) L021301] an improved inverse distance ladder method calibrated by the absolute measurements of the Hubble expansion rate at high redshifts from the cosmic chronometer data, and found no appealing evidence for new physics at the late time beyond the $\Lambda$CDM model characterized by a parametrization based on the cosmic age. In this paper, we further investigate the perspective of this improved inverse distance ladder method by including the late-time matter perturbation growth data. Independent of the dataset choices, model parametrizations, and diagnostic quantities ($S_8$ and $S_{12}$), the new physics at the late time beyond the $\Lambda$CDM model is strongly disfavoured so that the previous late-time no-go guide for the Hubble tension is further strengthened.

We model neutron stars as magnetised hybrid stars with an abrupt hadron-quark phase transition in their cores, taking into account current constraints from nuclear experiments and multi-messenger observations. We include magnetic field effects considering the Landau level quantisation of charged particles and the anomalous magnetic moment of neutral particles. We construct the magnetised hybrid equation of state, and we compute the particle population, the matter magnetisation and the transverse and parallel pressure components. We integrate the stable stellar models, considering the dynamical stability for \emph{rapid} or \emph{slow} hadron-quark phase conversion. Finally, we calculate the frequencies and damping times of the fundamental and $g$ non-radial oscillation modes. The latter, a key mode to learn about phase transitions in compact objects, is only obtained for stars with slow conversions. For low magnetic fields, we find that one of the objects of the GW170817 binary system might be a hybrid star belonging to the slow extended stability branch. For magnetars, we find that a stronger magnetic field always softens the hadronic equation of state. Besides, only for some parameter combinations a stronger magnetic field implies a higher hybrid star maximum mass. Contrary to previous results, the incorporation of anomalous magnetic moment does not affect the studied astrophysical quantities. We discuss possible imprints of the microphysics of the equation of state that could be tested observationally in the future, and that might help infer the nature of dense matter and hybrid stars.

A key assumption in quasar absorption line studies of the circumgalactic medium (CGM) is that each absorption component maps to a spatially isolated "cloud" structure that has single valued properties (e.g. density, temperature, metallicity). We aim to assess and quantify the degree of accuracy underlying this assumption. We used adaptive mesh refinement hydrodynamic cosmological simulations of two $z=1$ dwarf galaxies and generated synthetic quasar absorption-line spectra of their CGM. For the SiII $\lambda 1260$ transition, and the CIV $\lambda\lambda1548, 1550$ and OVI $\lambda\lambda1031, 1037$ fine-structure doublets, we objectively determined which gas cells along a line-of-sight (LOS) contribute to detected absorption. We implemented a fast, efficient, and objective method to define individual absorption components in each absorption profile. For each absorption component, we quantified the spatial distribution of the absorbing gas. We studied a total of 1,302 absorption systems containing a total of 7,755 absorption components. 48% of SiII, 68% of CIV, and 72% of OVI absorption components arise from two or more spatially isolated "cloud" structures along the LOS. Spatially isolated "cloud" structures were most likely to have cloud-cloud LOS separations of 0.03$R_{vir}$, 0.11$R_{vir}$, and 0.13$R_{vir}$ for SiII, CIV, and OVI, respectively. There can be very little overlap between multi-phase gas structures giving rise to absorption components. If our results reflect the underlying reality of how absorption lines record CGM gas, they place tension on current observational analysis methods as they suggest that component-by-component absorption line formation is more complex than is assumed and applied for chemical-ionisation modelling.

Self interaction of particulate dark matter may help thermalising the galactic center and driving core formation. The core radius is expectantly sensitive to the self interaction strength of dark matter. In this paper we study the feasibility of constraining dark matter self interaction from the distribution of the core radius in isolated haloes. We perform systematic $N$-body simulations of isolated galactic haloes in the mass range of $10^{10} $-$10^{15}M_{\odot}$ incorporating the impact of DM self interactions. Comparing the simulated profiles with observational data provides conservative upper limit on the self coupling cross-section $ \sigma/m_{\rm DM} < $ $ 9.8 $ $\ \rm cm^2 /\rm gm $ at $ 95 \% $ confidence level. We report significant dependence of the derived bounds on the galactic density distribution models assumed in the analysis.

Spectral representations have been shown to provide an efficient way to represent the poorly understood high-density portion of the neutron-star equation of state. This paper shows how the efficiency and accuracy of those representations can be improved by a very simple change.

Many extensions of the Standard Model of particle physics such as superstring and superbrane theories predict the existence of axion-like particles (ALPs). ALPs are very elusive particles, which primarily interact with photons and in the presence of an external magnetic field two effects are produced: (i) photon-ALP oscillations, (ii) change of the polarization state of photons. The astrophysical context represents the best possibility to obtain indirect evidence for the ALP existence thanks to the various effects that photon-ALP interaction produces. Great attention has been paid so far to the former effect: photon-ALP interaction modifies the transparency of the crossed media and final spectra are altered presenting either a flux excess or irregularities or both these features. Two hints at ALP existence have also been discovered. However, less interest has been attracted by the latter main ALP effect: the modification of photon polarization. In this paper we want to address it both in the X-ray and in the high-energy (HE) bands. In particular, we analyze the photon degree of linear polarization and the polarization angle when photon-ALP interaction is present concerning photons generated in the central region of galaxy clusters: we study Perseus and Coma. We observe that photon-ALP interaction substantially changes the photon polarization expected from standard physics and that it shows interesting features both in the X-ray and in the HE band. We conclude that the ALP-induced polarization effects are more likely detectable from the proposed missions like COSI, e-ASTROGAM and AMEGO in the HE range.

We analyze the parsec-scale jet kinematics from 2007 June to 2018 December of a sample of $\gamma$-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43 GHz under the VLBA-BU-BLAZAR program. We implement a novel piece-wise linear fitting method to derive the kinematics of 521 distinct emission knots from a total of 3705 total intensity images in 22 quasars, 13 BL Lacertae objects, and 3 radio galaxies. Apparent speeds of these components range from $0.01c$ to $78c$, and 18.6\% of knots (other than the "core") are quasi-stationary. One-fifth of moving knots exhibit non-ballistic motion, with acceleration along the jet within 5 pc of the core (projected) and deceleration farther out. These accelerations occur mainly at locations coincident with quasi-stationary features. We calculate the physical parameters of 273 knots with statistically significant motion, including their Doppler factors, Lorentz factors, and viewing angles. We determine the typical values of these parameters for each jet and the average for each subclass of active galactic nuclei. We investigate the variability of the position angle of each jet over the ten years of monitoring. The fluctuations in position of the quasi-stationary components in radio galaxies tend to be parallel to the jet, while no directional preference is seen in the components of quasars and BL Lacertae objects. We find a connection between $\gamma$-ray states of blazars and their parsec-scale jet properties, with blazars with brighter 43 GHz cores typically reaching higher $\gamma$-ray maxima during flares.

Propagation of the finite amplitude electromagnetic wave through the partially spin-polarized degenerate plasmas leads to the instability. The instability happens at the interaction of the electromagnetic wave with the small frequency longitudinal spin-electron-acoustic waves. Strongest instability happens in the high density degenerate plasmas with the Fermi momentum close to $m_{e}c$, where $m_{e}$ is the mass of electron, and $c$ is the speed of light. The increase of the increment of instability with the growth of the spin polarization of plasmas is found.

Using the measurements of tidal deformations in the binary neutron star (BNS) coalescences can obtain the information of redshifts of gravitational wave (GW) sources, and thus actually the cosmic expansion history can be investigated by solely using such GW dark sirens. To do this, the key is to get large amounts of accurate GW data, which can be achieved by employing the third-generation (3G) GW detectors. In this paper, we wish to offer an answer to the question of whether the Hubble constant and the equation of state (EoS) of dark energy can be precisely measured by solely using GW dark sirens. We find that in the era of 3G GW detectors ${\cal O}(10^5)$-${\cal O}(10^6)$ dark siren data (with the tidal measurements) can be obtained in a several-year observation, and thus using only dark sirens can actually achieve the precision cosmology. Based on a network of 3G detectors, we obtain the constraint precisions of $0.1\%$ and $0.6\%$ for the Hubble constant $H_0$ and the constant EoS of dark energy $w$, respectively; for a two-parameter EoS parametrization of dark energy, the precision of $w_0$ is $1.4\%$ and the error of $w_a$ is 0.086. We conclude that 3G GW detectors would lead to breakthroughs in solving the Hubble tension and revealing the nature of dark energy.

Ion cyclotron resonance is one of the fundamental energy conversion processes through field-particle interaction in collisionless plasmas. However, the key evidence for ion cyclotron resonance (i.e., the coherence between electromagnetic fields and the ion phase space density) and the resulting damping of ion cyclotron waves (ICWs) has not yet been directly observed. Investigating the high-quality measurements of space plasmas by the Magnetospheric Multiscale (MMS) satellites, we find that both the wave electromagnetic field vectors and the bulk velocity of the disturbed ion velocity distribution rotate around the background magnetic field. Moreover, we find that the absolute gyro-phase angle difference between the center of the fluctuations in the ion velocity distribution functions and the wave electric field vectors falls in the range of (0, 90) degrees, consistent with the ongoing energy conversion from wave-fields to particles. By invoking plasma kinetic theory, we demonstrate that the field-particle correlation for the damping ion cyclotron waves in our theoretical model matches well with our observations. Furthermore, the wave electric field vectors ($\delta \mathbf{E'}_{\mathrm {wave,\perp}}$), the ion current density ($\delta \mathbf{J}_\mathrm {i,\perp}$) and the energy transfer rate ($\delta \mathbf{J}_\mathrm {i,\perp}\cdot \delta \mathbf{E'}_{\mathrm {wave,\perp}}$) exhibit quasi-periodic oscillations, and the integrated work done by the electromagnetic field on the ions are positive, indicates that ions are mainly energized by the perpendicular component of the electric field via cyclotron resonance. Therefore, our combined analysis of MMS observations and kinetic theory provides direct, thorough, and comprehensive evidence for ICW damping in space plasmas.

The equation of state (EoS) and composition of dense and hot $\Delta$-resonance admixed hypernuclear matter is studied under conditions that are characteristic of neutron star binary merger remnants and supernovas. The cold, neutrino free regime is also considered as a reference for the astrophysical constraints on the EoS of dense matter. Our formalism uses the covariant density functional (CDF) theory successfully adapted to include the full $J^P=1/2^+$ baryon octet and non-strange members of $J^P=3/2^+$ decouplet with density-dependent couplings that have been suitably adjusted to the existing laboratory and astrophysical data in the nuclear and hypernuclear sectors. The effect of $\Delta$-resonances at finite temperatures is to soften the EoS of hypernuclear matter at intermediate densities and stiffen it at high densities. At low temperatures, the heavy baryons $\Lambda$, $\Delta^-$,$\Xi^-$, $\Xi^0$ and $\Delta^0$ appear in the given order if the $\Delta$-meson couplings are close to those for the nucleon-meson couplings. As is the case for hyperons, the thresholds of $\Delta$-resonances move to lower densities with the increase of temperature indicating a significant fraction of $\Delta$s in the low-density subnuclear regime. We find that the $\Delta$-resonances comprise a significant fraction of baryonic matter, of the order of $10\%$ at temperatures of the order of several tens of MeV in the neutrino-trapped regime and, thus, may affect the supernova and binary neutron star dynamics.

Cross sections and thermal rate coefficients are computed for electron-impact dissociative recombination and vibrational excitation/de-excitation of the N$^+_2$ molecular ion in its lowest six vibrational levels, for collision energies/temperatures up to 2.3 eV/5000 K.

We present a method to construct conformally curved initial data for charged black hole binaries with spin on arbitrary orbits. We generalize the superposed Kerr-Schild, extended conformal thin sandwich construction from [Lovelace et al., Phys. Rev. D {78}, 084017 (2008)] to use Kerr-Newman metrics for the superposed black holes and to solve the electromagnetic constraint equations. We implement the construction in the pseudospectral code SGRID. The code thus provides a complementary and completely independent excision-based construction, compared to the existing charged black hole initial data constructed using the puncture method [Bozzola and Paschalidis, Phys. Rev. D {99}, 104044 (2019)]. It also provides an independent implementation (with some small changes) of the Lovelace et al. vacuum construction. We construct initial data for different configurations of orbiting binaries, e.g., with black holes that are highly charged or rapidly spinning (90 and 80 percent of the extremal values, respectively, for this initial test, though the code should be able to produce data with even higher values of these parameters using higher resolutions), as well as for generic spinning, charged black holes. We carry out exploratory evolutions with the finite difference, moving punctures codes BAM (in the vacuum case) and HAD (for head-on collisions including charge), filling inside the excision surfaces. In the charged case, evolutions of these initial data provide a proxy for binary black hole waveforms in modified theories of gravity. Moreover, the generalization of the construction to Einstein-Maxwell-dilaton theory should be straightforward.