Papers for Thursday, Jun 09 2022

We aim to study the dynamics of tidally induced spiral arms in our Galaxy disc in the context of the different encounters with Sagittarius. We build toy models of the interaction between a host and a satellite galaxy using orbital integrations after a tidal distant encounter. We derive analytically the shape of the structures seen in phase space as a function of time for simple power-law potentials. We compare these models to a more realistic N-body simulation and to real data. As previously found, an impulsive distant tidal approach of a satellite leads to 2-armed spiral structure, made of orbits in between their apocentres and pericentres, thus, corresponding to regions with negative average galactocentric radial velocity. The 2-arm pattern rotates at an angular speed of $\Omega-1/2\kappa$ which depends on Galactocentric radius, thus causing a wind-up with time. This winding produces ridges in the $R$-$V_\phi$ projection with alternating signs of $V_R$ and oscillations of $V_R$ in the $L_Z$-$\phi$ space, like those in the Gaia data. The frequency of these kinematic features increases with time, offering a powerful means to infer the potential and the perturbation's onset time and azimuthal phase. Fourier analysis allows to date the impact times of simple models and even to date perturbations from various pericentric passages. For the MW, the Fourier analysis indicates a superposition of two frequencies, confirming previous studies. Assuming that both are due to impulsive distant pericentre passages, we find perturbation times <0.4 Gyr and in the range of 0.7-1.8 Gyr. The latter is compatible with a previous pericentre of Sagittarius and would be associated to about 4 wraps of the spiral arms in the observed radial range. Further work on the self-gravitating response of galactic discs and possible degeneracies with secular processes induced by the bar is necessary. (abridged)

Great strides have been made in recent years in the understanding of the mechanisms involved in the formation and evolution of planetary systems; despite this, many observational facts still do not have an explanation. A great contribution to the study of planetary formation processes comes from the study of young, low-mass planets, with short orbital periods. In the last years, the TESS satellite has identified many planets of this kind, and their characterization is mandatory to understand how they formed and evolved. Within the framework of the GAPS project, we performed the validation and characterization of the ultra-short period planet (USPP) TOI-1807b, orbiting its young host star BD+39 2643 (~300 Myr) in only 13 hours. This is the youngest USPP discovered so far. Thanks to a joint modeling of the stellar activity and planetary signals in the TESS light curve and in HARPS-N radial-velocity measurements, combined with accurate estimation of stellar parameters, we validated the planetary nature of TOI-1807b and measured its orbital and physical parameters. By using astrometric, photometric, and spectroscopic observations we found that BD+39 2643 is a young, active K dwarf star, member of a 300+/-80 Myr old moving group and that it rotates in Prot=8.8+/-0.1 days. This star hosts an USPP with an orbital period of only P_b=0.54937+/-0.00001 d. Thanks to the exquisite photometric and spectroscopic series, and the accurate information on the stellar activity, we measured both the radius and the mass of TOI-1807b with high precision, obtaining R_b=1.37+/-0.09 R_Earth and M_b=2.57+/-0.50 M_Earth. These planet parameters correspond to a rocky planet with an Earth-like density and no extended H/He envelope. From the analysis of the age-R_P distribution for planets with well measured ages, we inferred that TOI-1807b may have already lost a large part of its atmosphere during its 300 Myr life.

Cosmic metallicity evolution possibly creates the diversity of star formation modes at different epochs. Gravitational fragmentation of circumstellar discs provides an important formation channel of multiple star systems, including close binaries. We here study the nature of disc fragmentation, systematically performing a suite of two-dimensional radiation-hydrodynamic simulations, in a broad range of metallicities, from the primordial to the solar values. In particular, we follow relatively long-term disc evolution over 15 kyr after the disc formation, incorporating the effect of heating by the protostellar irradiation. Our results show that the disc fragmentation occurs at all metallicities $1$--$0$ $Z_{\odot}$, yielding self-gravitating clumps. Physical properties of the clumps, such as their number and mass distributions, change with the metallicity due to different gas thermal evolution. For instance, the number of clumps is the largest for the intermediate metallicity range of $10^{-2}$--$10^{-5}$ $Z_{\odot}$, where the dust cooling is effective exclusively in a dense part of the disc and causes the fragmentation of spiral arms. The disc fragmentation is more modest for $1$--$0.1$ $Z_{\odot}$ thanks to the disc stabilization by the stellar irradiation. Such metallicity dependence agrees with the observed trend that the close binary fraction increases with decreasing metallicity in the range of $1$--$10^{-3}$ $Z_{\odot}$.

I present a new technique for the measurement of the growth of cosmic structures via the power spectrum of weak lensing cosmic shear. It is based on a template-fitting approach, where a redshift-dependent amplitude of lensing modulates a fixed template power spectrum. Such an amplitude, which is promoted to a free parameter and fit against tomographic cosmic shear data, reads $D(z)\,\sigma_8\,\Omega_{{\rm m},0}=:\Omega\sigma_8(z)$, with $D(z)$ the growth factor, $\sigma_8$ a proxy for the overall amplitude of the matter power spectrum, and $\Omega_{{\rm m},0}$ the present-day matter abundance. I show that this method is able to correctly reconstruct $\Omega\sigma_8$ at the per cent level across redshift, thus allowing us to measure the growth of structures unbiased by observing discrete tracers. Moreover, I only makes use of measurements on linear scales. The method is highly complementary to measurements of the bias and growth, $b\sigma_8(z)$ and $f\sigma_8(z)$, from galaxy clustering analysis. I also demonstrate that the method is robust against an incorrect choice of cosmological parameters in the template, thanks to the inclusion of an Alcock-Paczy\'nski parameter.

We report new results for the gravitational microlensing target OGLE-2011-BLG-0950 from adaptive optics (AO) images using the Keck observatory. The original analysis by Choi et al. 2012 reports degenerate solutions between planetary and stellar binary lens systems. This is due to a degeneracy in high magnification events where the shape of the light curve peak can be explained by a source approach to two different cusp geometries with different source radius crossing times. This particular case is the most important type of degeneracy for exoplanet demographics, because the distinction between a planetary mass or stellar binary companion has direct consequences for microlensing exoplanet statistics. The 8 and 10-year baselines between the event and the Keck observations allow us to directly measure a relative proper motion of $4.20\pm 0.21\,$mas/yr, which confirms the detection of the lens star system and directly rules out the planetary companion models that predict a ${\sim}4 \times$ smaller relative proper motion. The combination of the lens brightness and close stellar binary light curve parameters yield primary and secondary star masses of $M_{A} = 1.12^{+0.06}_{-0.04}M_\odot$ and $M_{B} = 0.47^{+0.04}_{-0.03}M_\odot$ at a distance of $D_L = 6.70^{+0.55}_{-0.30}\,$kpc, and a primary-secondary projected separation of $0.39^{+0.05}_{-0.04}\,$AU. Since this degeneracy is likely to be common, the high resolution imaging method described here will be used to disentangle the central caustic cusp approach degeneracy for events observed by the \textit{Roman} exoplanet microlensing survey using the \textit{Roman} images taken near the beginning or end of the survey.

A tight relation between [C II] $ 158 \ {\rm{\mu m}}$ line luminosity and star formation rate (SFR) is observed in local galaxies. At $z > 5$, galaxies instead deviate downwards from the local $\Sigma_{\rm{[C II]}}-\Sigma_{\rm{SFR}}$ relation. This deviation might be caused by different interstellar medium (ISM) properties in galaxies at early epochs. We combine the [C II] and SFR data with C III] $\lambda1909$ line observations and our physical models. We additionally investigate how the ISM properties: burstiness $\kappa_s$, total gas density $n$, and metallicity $Z$, affect the deviation from the $\Sigma_{\rm{[C II]}}-\Sigma_{\rm{SFR}}$ relation in these sources. We present the VLT/X-SHOOTER observations targeting the C III] $\lambda1909$ line emission in three galaxies at $5.5<z<7.0$. We extend our sample of galaxies by including archival X-SHOOTER and MUSE data of eight sources at $2<z<7$ and eleven star-forming systems at $6 < z< 7.5$ with C III] or [C II] data reported in the literature. We detect C III] $\lambda \lambda1907, 1909$ line emission in HZ10 and derive the intrinsic flux of the C III] $ \lambda1909$ line. We constrain the ISM properties of our sample of galaxies: $\kappa_s$, $n$, and $Z$, by applying our physically motivated model based on the MCMC algorithm. For the most part, high-$z$, star-forming galaxies show subsolar metallicities. The majority of the sources have $\log{(\kappa_s)} \gtrsim 1$, i.e., they overshoot the Kennicutt-Schmidt relation by about one order of magnitude. This suggests that the whole KS relation might be shifted upwards at early times. Next, all the high-$z$ galaxies of our sample lie below the $\Sigma_{\rm{[C II]}}-\Sigma_{\rm{SFR}}$ local relation. The total gas density $n$ shows the strongest correlation with the deviation from the local $\Sigma_{\rm{[C II]}}-\Sigma_{\rm{SFR}}$ relation, in agreement with theoretical models.

We combine results from deep ALMA observations of massive ($M_*>10^{10}\;M_{\odot}$) galaxies at different redshifts to show that the column density of their inter stellar medium (ISM) rapidly increases towards early cosmic epochs. Our analysis includes objects from the ASPECS and ALPINE large programs, as well as individual observations of $z\sim 6$ QSO hosts. When accounting for non-detections and correcting for selection effects, we find that the median surface density of the ISM of the massive galaxy population evolves as $\sim(1+z)^{3.3}$. This means that the ISM column density towards the nucleus of a $z>3$ galaxy is typically $>100$ times larger than locally, and it may reach values as high as Compton-thick at $z\gtrsim6$. Remarkably, the median ISM column density is of the same order of what is measured from X-ray observations of large AGN samples already at $z\gtrsim2$. We develop a simple analytic model for the spatial distribution of ISM clouds within galaxies, and estimate the total covering factor towards active nuclei when obscuration by ISM clouds on the host scale is added to that of pc-scale circumnuclear material (the so-called 'torus'). The model includes clouds with a distribution of sizes, masses, and surface densities, and also allows for an evolution of the characteristic cloud surface density with redshift, $\Sigma_{c,*}\propto(1+z)^\gamma$. We show that, for $\gamma=2$, such a model successfully reproduces the increase of the obscured AGN fraction with redshift that is commonly observed in deep X-ray surveys, both when different absorption thresholds and AGN luminosities are considered. Our results suggest that 80-90\% of supermassive black holes in the early Universe ($z>6-8$) are hidden to our view, primarily by the ISM in their hosts. [abridged]

A multiwavelength study of galaxies is important to understand their formation and evolution. Only in the recent past, thanks to the Atacama Large (Sub) Millimeter Array (ALMA), were we able to study the far-infrared (IR) properties of galaxies at high redshifts. In this article, we summarize recent research highlights and their significance to our understanding of early galaxy evolution from the ALPINE survey, a large program with ALMA to observe the dust continuum and 158um C+ emission of normal star-forming galaxies at z = 4-6. Combined with ancillary data at UV through near-IR wavelengths, ALPINE provides the currently largest multiwavelength sample of post-reionization galaxies and has advanced our understanding of (i) the demographics of C+ emission; (ii) the relation of star formation and C+ emission; (iii) the gas content; (iv) outflows and enrichment of the intergalactic medium; and (v) the kinematics, emergence of disks, and merger rates in galaxies at z > 4. ALPINE builds the basis for more detailed measurements with the next generation of telescopes, and places itself as an important post-reionization baseline sample to allow a continuous study of galaxies over 13 billion years of cosmic time.

(Abridged) The lifetime of protoplanetary disks around young stars limits the timescale when planets form. A disk dissipation timescale < 10 Myr was inferred from surveys providing the fraction of stars with disks in young stellar clusters with different ages. However, most previous surveys focused on the compact region within ~ 2 pc from the clusters' centers, for which the disk fraction information considering the outer part is practically absent. We aim to test if disk fraction estimates change when inferred from an extended region around the clusters' centers. Gaia EDR3 data and a best-suited, Virtual Observatory (VO)-based tool -Clusterix-, are used to identify member stars for a representative sample of 19 young clusters considering two concentric fields of view (FOV) with radii ~ 20 pc and ~ 2 pc. Our analysis reveals that the inner disk fractions inferred from the compact and the extended regions are equal within ~ 10%, which does not support a previous hypothesis proposing that disk fractions should be significantly larger considering extended regions. A list of member and disk stars in each cluster is provided and stored in a VO-compliant archive. Averaged values and plots characterizing the whole clusters are also provided, including HR diagrams based on Gaia colors and absolute magnitudes. Our results cover the largest fields ever probed when dealing with disk fractions for all clusters analysed, and imply that their complete characterization requires the use of wide FOVs. The resulting database is a benchmark for future detailed studies of young clusters, whose disk fractions must be accurately determined by using multi-wavelength analysis potentially combined with data from coming Gaia releases.

We present a reanalysis of reverberation-mapping data from 2005 for the Seyfert galaxy NGC 4151, supplemented with additional data from the literature to constrain the continuum variations over a significantly longer baseline than the original monitoring program. Modeling of the continuum light curve and the velocity-resolved variations across the H$\beta$ emission line constrains the geometry and kinematics of the broad line region (BLR). The BLR is well described by a very thick disk with similar opening angle ($\theta_o \approx 57^{\circ}$) and inclination angle ($\theta_i \approx 58^{\circ}$), suggesting that our sight line towards the innermost central engine skims just above the surface of the BLR. The inclination is consistent with constraints from geometric modeling of the narrow line region, and the similarity between the inclination and opening angles is intriguing given previous studies of NGC 4151 that suggest BLR gas has been observed temporarily eclipsing the X-ray source. The BLR kinematics are dominated by eccentric bound orbits, with $\sim10$% of the orbits preferring near-circular motions. With the BLR geometry and kinematics constrained, the models provide an independent and direct black hole mass measurement of $\log M_{\rm BH}/M_{\odot} = 7.22^{+0.11}_{-0.10}$ or $M_{\rm BH}=1.66^{+0.48}_{-0.34}\times10^7 M_{\odot}$, which is in good agreement with mass measurements from stellar dynamical modeling and gas dynamical modeling. NGC 4151 is one of the few nearby broad-lined Seyferts where the black hole mass may be measured via multiple independent techniques, and it provides an important test case for investigating potential systematics that could affect the black hole mass scales used in the local Universe and for high-redshift quasars.

Exoplanet CoRoT-1 b is intriguing because we predict it to be a transitional planet between hot Jupiters (equilibrium temperatures ~ 1500 K) and ultra-hot Jupiters (equilibrium temperatures > 2000 K). In 2012, observations of CoRoT-1 b included one primary transit and three secondary eclipses with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) combined with the G141 grism (1.1-1.7 $\mu$m) in stare mode. We aimed to further investigate CoRoT-1 b through its secondary eclipses, producing spectrophotometric light curves corrected for charge trapping, also known as the ramp effect in time-series observations with the WFC3. We found that, when correcting for the ramp effect and using the typically discarded first orbit, we are better capable of constraining and optimizing the emission and transmission spectra. We did a grid retrieval in this transitional temperature regime and found the spectra for CoRoT-1 b to be featureless and to agree with an inverted temperature-pressure (T-P) profile. We note, however, that the contribution function for the WFC3 indicates pressures probed near $10^{-3}$ to $10^{0}$ bar, which correspond to a nearly isothermal region in our T-P profile, thereby indicating that the inversion at high altitude is model-dependent. Despite no distinct features, the analysis done on CoRoT-1 b paves the way to high-precision results with stare mode spectroscopy. As a new generation of observations from the James Webb Space Telescope (JWST) approaches, CoRoT-1 b might be an interesting follow-up target because the time-series spectroscopic modes of JWST's NIRSpec, MIRI, and NIRCam instruments will be analogous to HST's stare mode.

This work utilizes established models of synchrotron-powered light curves for core-collapse supernovae in dense circumstellar environments, namely type IIn and Ibn, to demonstrate the potential for detecting millimeter emission from these events. The progenitor types of these supernovae are still an open question, but using the synchrotron light curves as probes for the circumstellar environments could shed light on the mass-loss histories of the progenitors and discern between different theories. Observations in millimeter bands are particularly fruitful, as they probe regions at smaller radii and higher ambient densities, where centimeter emission tends to be self-absorbed. In our application of these light curves, we explore a diversity of progenitor types and mass-loss profiles to understand their effects on the light curve shapes. Additionally, we fit model parameters to the 8\,GHz light curve of type IIn supernova 2006jd and then create millimeter light curves using these parameters to show the possibility of detecting an early millimeter peak from such an event. We predict that next generation millimeter surveys will possess the capability to detect nearby and extreme events. However, there is a pressing need for millimeter follow-up of optically discovered interacting supernovae to more completely sample the true population.

We present Gemini South/IGRINS observations of the 1060 K T6 dwarf 2MASS J08173001$-$6155158 with unprecedented resolution ($R\equiv\lambda/\Delta\lambda=45\,000$) and signal-to-noise ratio (SNR > 200) for a late-type T dwarf. We use this benchmark observation to test the reliability of molecular line lists used up-to-date atmospheric models. We determine which spectroscopic regions should be used to estimate the parameters of cold brown dwarfs and, by extension, exoplanets. We present a detailed spectroscopic atlas with molecular identifications across the $H$ and $K$ bands of the near-infrared. We find that water (H$_2$O) line lists are overall reliable. We find the most discrepancies amongst older methane (CH$_4$) line lists, and that the most up-to-date CH$_4$ line lists correct many of these issues. We identify individual ammonia (NH$_3$) lines, a hydrogen sulfide (H$_2$S) feature at 1.5900 $\mu$m, and a molecular hydrogen (H$_2$) feature at 2.1218 $\mu$m. These are the first unambiguous detections of H$_2$S and H$_2$ absorption features in an extra-solar atmosphere. With the H$_2$ detection, we place an upper limit on the atmospheric dust concentration of this T6 dwarf: at least 500 times less than the interstellar value, implying that the atmosphere is effectively dust-free. We additionally identify several features that do not appear in the model spectra. Our assessment of the line lists is valuable for atmospheric model applications to high-dispersion, low-SNR, high-background spectra, such as an exoplanet around a star. We demonstrate a significant enhancement in the detection of the CH$_4$ absorption signal in this T6 dwarf with the most up-to-date line lists.

Supernovae of Type Iax (SNe Iax) are an accepted faint subclass of hydrogen-free supernovae. Their origin, the nature of the progenitor systems, however, is an open question. Recent studies suggest that the weak deflagration explosion of a near-Chandrasekhar-mass white dwarf in a binary system with a helium star donor could be the origin of SNe Iax. In this scenario, the helium star donor is expected to survive the explosion. We use the one-dimensional stellar evolution codes \textsc{MESA} and \textsc{Kepler} to follow the post-impact evolution of the surviving helium companion stars. The stellar models are based on our previous hydrodynamical simulations of ejecta-donor interaction, and we explore the observational characteristics of these surviving helium companions. We find that the luminosities of the surviving helium companions increase significantly after the impact: They could vary from $2\mathord,500\,\mathrm{L_{\odot}}$ to $16\mathord,000\,\mathrm{L_{\odot}}$ for a Kelvin-Helmholtz timescale of about $10^{4}\,\mathrm{yr}$. After the star reaches thermal equilibrium, it evolves as an O-type hot subdwarf (sdO) star and continues its evolution along the evolutionary track of a normal sdO star with the same mass. Our results will help to identify the surviving helium companions of SNe Iax in future observations and to place new constraints on their progenitor models.

Recent studies have suggested that type Iax supernovae (SNe Iax) are likely to result from a weak deflagration explosion of a Chandrasekhar-mass white dwarf in a binary system with a helium (He)-star companion. Assuming that most SNe Iax are produced from this scenario, in this work we extend our previous work on the three-dimensional hydrodynamical simulation of ejecta-companion interaction by taking the orbital and spin velocities of the progenitor system into account. We then follow the post-impact evolution of a surviving He-star companion by using the one-dimensional stellar evolution code \textsc{MESA}. We aim to investigate the post-explosion rotation properties of a He-star companion in SNe Iax. We find that the He-star companion spins down after the impact due to the angular-momentum loss and expansion caused by the mass-stripping and shock heating during the interaction. This leads to the situation where the surface rotational speed of the surviving companion can drop to one-third of its pre-explosion value when it expands to a maximum radius a few years after the impact. Subsequently, the star shrinks and spins up again once the deposited energy is released. This spin-switching feature of the surviving He-star companions of SNe Iax may be useful for the identification of such objects in future observations.

A new class of models of stellar discs is introduced and used to build a self-consistent model of our Galaxy. The model is defined by the parameters that specify the action-based distribution functions (DFs) f(J) of four stellar discs (three thin-disc age cohorts and a thick disc), spheroidal bulge and spheroidal stellar and dark haloes. From these DFs plus a specified distribution of gas, we solve for the densities of stars and dark matter and the potential they generate. The principal observational constraints are the kinematics of stars with Gaia RVS data and the density of stars in the column above the Sun. The model predicts the density and kinematics of stars and dark matter throughout the Galaxy. We determine the structure of the dark halo prior to the infall of baryons. A simple extension of the DFs of stellar components to include chemistry allows the model to reproduce the way the Galaxy's chemistry is observed to vary in the (R,z) plane. Surprisingly, the data indicate that high-alpha stars are confined to orbits with J_z >~ 50 kpc km/s. The code used to create the model is available on Github.

Phosphorus (P) is a critical element for life on Earth yet the cosmic production sites of P are relatively uncertain. To understand how P has evolved in the solar neighborhood, we measured abundances for 163 FGK stars over a range of -1.09 $<$ [Fe/H] $<$ 0.47 using observations from the Habitable-zone Planet Finder (HPF) instrument on the Hobby-Eberly Telescope (HET). Atmospheric parameters were calculated by fitting a combination of astrometry, photometry, and Fe I line equivalent widths. Phosphorus abundances were measured by matching synthetic spectra to a P I feature at 10529.52 angstroms. Our [P/Fe] ratios show that chemical evolution models generally under-predict P over the observed metallicity range. Additionally, we find that the [P/Fe] differs by $\sim$ 0.1 dex between thin disk and thick disk stars that were identified with kinematics. The P abundances were compared with $\alpha$-elements, iron-peak, odd-Z, and s-process elements and we found that P in the disk most strongly resembles the evolution of the $\alpha$-elements. We also find molar P/C and N/C ratios for our sample match the scatter seen from other abundance studies. Finally, we measure a [P/Fe] = 0.09 $\pm$ 0.1 ratio in one low-$\alpha$ halo star and probable Gaia-Sausage-Enceladus (GSE) member, an abundance ratio $\sim$ 0.3 - 0.5 dex lower than the other Milky Way disk and halo stars at similar metallicities. Overall, we find that P is likely most significantly produced by massive stars in core collapse supernovae (CCSNe) based on the largest P abundance survey to-date.

The X-ray emission from the Sun reveals a very dynamic hot atmosphere, the corona, which is characterized by a complex morphology and broad range of timescales of variability and spatial structuring. The solar magnetic fields play a fundamental role in the heating and structuring of the solar corona. Increasingly higher quality X-ray solar observations with high spatial (down to subarcsec) and temporal resolution provide fundamental information to refine our understanding of the solar magnetic activity and of the underlying physical processes leading to the heating of the solar outer atmosphere. Here we provide a brief historical overview of X-ray solar observations and we summarize recent progress in our understanding of the solar corona as made possible by state-of-the-art current X-ray observations.

Photodissociation is one of the main destruction pathways for dicarbon (C$_{2}$) in astronomical environments such as diffuse interstellar clouds, yet the accuracy of modern astrochemical models is limited by a lack of accurate photodissociation cross sections in the vacuum ultraviolet range. C$_{2}$ features a strong predissociative $F\,^1\Pi_u - X\,^1\Sigma_g^+$ electronic transition near 130 nm originally measured in 1969; however, no experimental studies of this transition have been carried out since, and theoretical studies of the $F\,^1\Pi_u$ state are limited. In this work, potential energy curves of excited electronic states of C$_{2}$ are calculated with the aim of describing the predissociative nature of the $F\,^1\Pi_u$ state and providing new ab initio photodissociation cross sections for astrochemical applications. Accurate electronic calculations of 56 singlet, triplet, and quintet states are carried out at the DW-SA-CASSCF/MRCI+Q level of theory with a CAS(8,12) active space and the aug-cc-pV5Z basis set augmented with additional diffuse functions. Photodissociation cross sections arising from the vibronic ground state to the $F\,^1\Pi_u$ state are calculated by a coupled-channel model. The total integrated cross section through the $F\,^1\Pi_u$ $v=0$ and $v=1$ bands is 1.198$\times$10$^{-13} $cm$^2$cm$^{-1}$, giving rise to a photodissociation rate of 5.02$\times$10$^{-10}$ s$^{-1}$ under the standard interstellar radiation field, much larger than the rate in the Leiden photodissociation database. In addition, we report a new $2\,^1\Sigma_u^+$ state that should be detectable via a strong $2\,^1\Sigma_u^+-X\,^1\Sigma_g^+$ band around 116 nm.

We present the pulsar timing analysis of the accreting millisecond X-ray pulsar SWIFT J1749.4-2807 monitored by NICER and XMM-Newton during its latest outburst after almost eleven years of quiescence. From the coherent timing analysis of the pulse profiles, we updated the orbital ephemerides of the system. Large phase jumps of the fundamental frequency phase of the signal are visible during the outburst, consistent with what was observed during the previous outburst. Moreover, we report on the marginally significant evidence for non-zero eccentricity ($e\simeq 4\times 10^{-5}$) obtained independently from the analysis of both the 2021 and 2010 outbursts and we discuss possible compatible scenarios. Long-term orbital evolution of SWIFT J1749.4-2807 suggests a fast expansion of both the NS projected semi-major axis $(x)$, and the orbital period $(P_{\rm orb})$, at a rate of $\dot{x}\simeq 2.6\times 10^{-13}\,\text{lt-s}\,\text{s}^{-1}$ and $\dot{P}_{\rm orb}\simeq 4 \times 10^{-10}\,\text{s}\,\text{s}^{-1}$, respectively. SWIFT J1749.4-2807 is the only accreting millisecond X-ray pulsar, so far, from which the orbital period derivative has been directly measured from appreciable changes on the observed orbital period. Finally, no significant secular deceleration of the spin frequency of the compact object is detected, which allowed us to set a constraint on the magnetic field strength at the polar caps of $B_{PC}<1.3\times 10^{8}~\text{G}$, in line with typical values reported for AMXPs.

In connection with the exit of mankind and its production into open space, the problem of the nature of solar wind (SW) is acute. We have proved that a nonequilibrium inhomogeneous giant gas discharge with huge values of the E/N parameter, which determines the electron temperature, is realized in the heliosphere. This quasi-stationary discharge determines the main parameters of the slow SW in the heliosphere and is the initial background and energy reservoir for all more powerful electrical phenomena in the heliosphere, ionosphere and even in the upper atmosphere of the Earth and the positively charged Sun, connected with the entire heliosphere by reverse electron flows that are unable to leave the positively charged Sun and heliosphere. Our article is devoted to a comparison of the experimental profiles of the global electric field obtained using two methods: 1) by the electron velocity distribution function (in experiments with the Parker solar probe) and 2) by the types of positive ions in the SW (according to experiments on the Prognozz - 7 satellite). We have proved that the Pannekoek-Rosseland-Eddington model does not take into account the important role of high-energy runaway (escape from the Sun) electrons and, accordingly, the duality of electron flows in the heliosphere (from the Sun and towards the Sun). In our model, the slight difference between the opposite currents of high-energy (running away from the Sun) electrons and low-energy (returning to the Sun) electrons is compensated by the current of positive ions and protons from the positively charged Sun - SW (positive ions carry electrons with them).

The molecular ion H$_3^+$ is a potentially powerful tracer of the ionospheres and thermal structures of Jovian planets, but has never been detected in a planetary mass object outside of the solar system. Models predict that H$_3^+$ emission driven by EUV flux and solar wind on hot Jupiters, or by powerful aurorae on brown dwarfs, will be between $10^2$ and $10^5\times$ more intense than that of Jupiter. If optimal conditions for the production of emission do exist, the emission may be detectable by current ground-based instruments or in the near future. We present the first search for H$_3^+$ line emission in brown dwarfs with Keck/NIRSPEC $L^\prime$ high-resolution spectroscopy. Additionally, we survey stars hosting giant planets at semi-major axes near $0.1-0.2$ au, which models suggest may be the best planetary targets. No candidate H$_3^+$ emission is found. The limits we place on the emission of H$_3^+$ from brown dwarfs indicates that auroral generation of H$_3^+$ in these environments likely does not linearly scale from the processes found on Jupiter, plausibly due to deeper atmospheric penetration by precipitating auroral electrons. Detection of H$_3^+$ emission in brown dwarfs may be possible with the James Webb Space Telescope (JWST), or future thirty-meter class telescopes.

Supernova explosions, active galactic nuclei jets, galaxy--galaxy interactions and cluster mergers can drive turbulence in the circumgalactic medium (CGM) and in the intracluster medium (ICM). However, the exact nature of turbulence forced by these sources and its impact on the different statistical properties of the CGM/ICM and their global thermodynamics is still unclear. To investigate the effects of different types of forcing, we conduct high resolution ($1008^3$ resolution elements) idealised hydrodynamic simulations with purely solenoidal (divergence-free) forcing, purely compressive (curl-free) forcing, and natural mixture forcing (equal fractions of the two components). The simulations also include radiative cooling. We study the impact of the three different forcing modes (sol, comp, mix) on the morphology of the gas, its temperature and density distributions, sources and sinks of enstrophy, i.e., solenoidal motions, as well as the kinematics of hot ($\sim10^7~\mathrm{K}$) X-ray emitting and cold ($\sim10^4~\mathrm{K}$) H$\alpha$ emitting gas. We find that compressive forcing leads to stronger variations in density and temperature of the gas as compared to solenoidal forcing. The cold phase gas forms large-scale filamentary structures for compressive forcing and misty, small-scale clouds for solenoidal forcing. The cold phase gas has stronger large-scale velocities for compressive forcing. The natural mixture forcing shows kinematics and gas distributions intermediate between the two extremes, the cold-phase gas occurs as both large-scale filaments and small-scale misty clouds.

The Giant Magellan Telescope (GMT) design consists of seven circular 8.4-m diameter mirror segments that are separated by large > 30 cm gaps, creating the possibility of fluctuations in optical path differences due to flexure, segment vibrations, wind buffeting, temperature effects, and atmospheric seeing. In order to utilize the full diffraction-limited aperture of the GMT for natural guide star adaptive optics (NGSAO) science, the seven mirror segments must be co-phased to well within a fraction of a wavelength. The current design of the GMT involves seven adaptive secondary mirrors, an off-axis dispersed fringe sensor (part of the AGWS), and a pyramid wavefront sensor (PyWFS; part of the NGWS) to measure and correct the total path length between segment pairs, but these methods have yet to be tested "end-to-end" in a lab environment. We present the design and working prototype of a "GMT High-Contrast Adaptive Optics phasing Testbed" (p-HCAT) which leverages the existing MagAO-X AO instrument to demonstrate segment phase sensing and simultaneous AO-control for GMT NGSAO science. We present the first test results of closed-loop piston control with one GMT segment using MagAO-X's PyWFS and a novel Holographic Dispersed Fringe Sensor (HDFS) with and without simulated atmospheric turbulence. We show that the PyWFS alone was unsuccessful at controlling segment piston with generated ~ 0.6 arcsec and ~ 1.2 arcsec seeing turbulence due to non-linear modal cross-talk and poor pixel sampling of the segment gaps on the PyWFS detector. We report the success of an alternate solution to control piston using the novel HDFS while controlling all other modes with the PyWFS purely as a slope sensor (piston mode removed). This "second channel" WFS method worked well to control piston to within 50 nm RMS and $\pm$ 10 $\mu$m dynamic range under simulated 0.6 arcsec atmospheric seeing conditions.

The next generation of Giant Segmented Mirror Telescopes (GSMT) will have large gaps between the segments either caused by the shadow of the mechanical structure of the secondary mirror (E-ELT and TMT) or intrinsically by design (GMT). These gaps are large enough to fragment the aperture into independent segments that are separated by more than the typical Fried parameter. This creates piston and petals modes that are not well sensed by conventional wavefront sensors such as the Shack-Hartmann wavefront sensor or the pyramid wavefront sensor. We propose to use a new optical device, the Holographic Dispersed Fringe Sensor (HDFS), to sense and control these petal/piston modes. The HDFS uses a single pupil-plane hologram to interfere the segments onto different spatial locations in the focal plane. Numerical simulations show that the HDFS is very efficient and that it reaches a differential piston rms smaller than 10 nm for GMT/E-ELT/TMT for guide stars up to 13th J+H band magnitude. The HDFS has also been validated in the lab with MagAO-X and HCAT, the GMT phasing testbed. The lab experiments reached 5 nm rms piston error on the Magellan telescope aperture. The HDFS also reached 50 nm rms of piston error on a segmented GMT-like aperture while the pyramid wavefront sensor was compensating simulated atmosphere under median seeing conditions. The simulations and lab results demonstrate the HDFS as an excellent piston sensor for the GMT. We find that the combination of a pyramid slope sensor with a HDFS piston sensor is a powerful architecture for the GMT.

Fast material ejected dynamically over $<10$ ms during the merger of a binary neutron-star (BNS) system can give rise to distinctive electromagnetic counterparts to the system's gravitational-wave emission that can serve as a "smoking gun" to distinguish between a BNS and a NS-black-hole merger. We present novel ab-initio modeling of the associated kilonova precursor and kilonova afterglow based on three-dimensional general-relativistic magneto-hydrodynamic simulations of BNS mergers with tabulated, composition-dependent, finite-temperature equations of state (EOSs), weak interactions, and approximate neutrino transport. We analyze dynamical mass ejection from 1.35-1.35Msun binaries, typical of Galactic double-NS systems and consistent with properties of the first observed BNS merger GW170817, using three nuclear EOSs that span the range of allowed compactness. Nuclear reaction network calculations yield a robust 2nd-to-3rd-peak r-process. We find few x 1e-6Msun of fast ($v>0.6$c) ejecta that give rise to broad-band synchrotron emission on ~yr timescales, consistent with recent tentative evidence for excess X-ray/radio emission following GW170817. We find 2e-5Msun of free neutrons that power a kilonova precursor on <h timescale. A boost in early UV/optical brightness by a factor of a few due to previously neglected relativistic effects, with appreciable enhancements up to 10h post-merger, provides promising prospects for future detection with UV/optical telescopes such as Swift or ULTRASAT out to 250Mpc. We find that a recently predicted opacity boost due to highly ionized lanthanides at ~70000K is unlikely to affect the early kilonova lightcurve based on the obtained ejecta structures. Azimuthal inhomogeneities in dynamical ejecta composition for soft EOSs found here ("lanthanide/actinide pockets") may have observable consequences for both early kilonova and late-time nebular emission.

A tetrahedron is the simplest shape that cannot be rotated into its mirror image in 3D. The 4-Point Correlation Function (4PCF), which quantifies excess clustering of quartets of galaxies over random, is the lowest-order statistic sensitive to parity violation. Each galaxy defines one vertex of the tetrahedron. Parity-odd modes of the 4PCF probe an imbalance between tetrahedra and their mirror images. We measure these modes from the largest currently available spectroscopic samples, the 280,067 Luminous Red Galaxies (LRGs) of BOSS DR12 LOWZ ($\bar{z} = 0.32$) and the 803,112 LRGS of BOSS DR12 CMASS ($\bar{z} = 0.57$). In LOWZ we find $3.1\sigma$ evidence for a non-zero parity-odd 4PCF, and in CMASS we detect a parity-odd 4PCF at $7.1\sigma$. Gravitational evolution alone does not produce this effect; parity-breaking in LSS, if cosmological in origin, must stem from the epoch of inflation. We have explored many sources of systematic error and found none that can produce a spurious parity-odd \textit{signal} sufficient to explain our result. Underestimation of the \textit{noise} could also lead to a spurious detection. Our reported significances presume that the mock catalogs used to calculate the covariance sufficiently capture the covariance of the true data. We have performed numerous tests to explore this issue. The odd-parity 4PCF opens a new avenue for probing new forces during the epoch of inflation with 3D LSS; such exploration is timely given large upcoming spectroscopic samples such as DESI and Euclid.

We investigate the formation of molecular clouds from atomic gas by using three-dimensional magnetohydrodynamical simulations,including non-equilibrium chemical reactions, heating/cooling processes, and self-gravity by changing the collision speed $V_0$ and the angle $\theta$ between the magnetic field and colliding flow. We found that the efficiency of the dense gas formation depends on $\theta$. For small $\theta$, anisotropic super-Alfv\'enic turbulence delays the formation of gravitationally unstable clumps. An increase in $\theta$ develops shock-amplified magnetic fields along which the gas is accumulated, making prominent filamentary structures. We further investigate the statistical properties of dense clumps identified with different density thresholds. The statistical properties of the dense clumps with lower densities depend on $V_0$ and $\theta$ because their properties are inherited from the global turbulence structure of the molecular clouds. By contrast, denser clumps appear to have asymptotic universal statistical properties, which do not depend on the properties of the colliding flow significantly. The internal velocity dispersions approach subsonic and plasma $\beta$ becomes order of unity. We develop an analytic formula of the virial parameter which reproduces the simulation results reasonably well. This property may be one of the reasons for the universality of the initial mass function of stars.

M dwarfs are the dominating type of stars in the solar neighbourhood. They serve as excellent tracers for the study of the distribution and properties of the nearby interstellar dust. In this work, we aim to obtain high accuracy reddening values of M dwarf stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 8 (DR8). Combining the LAMOST spectra with the high-quality optical photometry from the Gaia Early Data Release 3 (Gaia EDR3), we have estimated the reddening values $E(G_{\rm BP}-G_{\rm RP})$ of 641,426 M dwarfs with the machine-learning algorithm Random Forest regression. The typical reddening uncertainty is only 0.03 mag in $E(G_{\rm BP}-G_{\rm RP})$. We have obtained the reddening coefficient $R_{(G_{\rm BP}-G_{\rm RP})}$, which is a function of the stellar intrinsic colour $(G_{\rm BP}-G_{\rm RP})_0$ and reddening value $E(B-V)$. The values of $E(B-V)$ are also provided for the individual stars in our catalogue. Our resultant high accuracy reddening values of M dwarfs, combined with the Gaia parallaxes, will be very powerful to map the fine structures of the dust in the solar neighbourhood.

Here we present results from over 500 kiloseconds Chandra and XMM-Newton observations of the cool core of the Centaurus cluster. We investigate the spatial distributions of the O, Mg, Si, S, Ar, Ca, Cr, Mn, Fe, and Ni abundances in the intracluster medium with CCD detectors, and those of N, O, Ne, Mg, Fe, and Ni with the Reflection Grating Spectrometer (RGS). The abundances of most of the elements show a sharp drop within the central 18 arcsec, although different detectors and atomic codes give significantly different values. The abundance ratios of the above elements, including Ne/Fe with RGS, show relatively flat radial distributions. In the innermost regions with the dominant Fe-L lines, the measurements of the absolute abundances are challenging. For example, AtomDB and SPEXACT give Fe = 0.5 and 1.4 solar, respectively, for the spectra from the innermost region. These results suggest some systematic uncertainties in the atomic data and response matrices at least partly cause the abundance drop rather than the metal depletion into the cold dust. Except for super-solar N/Fe and Ni/Fe, sub-solar Ne/Fe, and Mg/Fe, the abundance pattern agrees with the solar composition. The entire pattern is challenging to reproduce with the latest supernova nucleosynthesis models. Observed super-solar N/O and comparable Mg abundance to stellar metallicity profiles imply the mass-loss winds dominate the intracluster medium in the brightest cluster galaxy. The solar Cr/Fe and Mn/Fe ratios indicate a significant contribution of near- and sub-Chandrasekhar mass explosions of Type Ia supernovae.

The repeating fast radio burst (FRB) source FRB 20200120E is exceptional because of its proximity ($d=3.6$ Mpc) and association with a globular cluster. Here we report $60$ bursts detected with the 100-m Effelsberg telescope at 1.4 GHz. We observe large variations in the burst rate, and report the first FRB 20200120E `burst storm', where the source suddenly became active and 53 bursts occurred within only 40 minutes. We find no strict periodicity in the burst arrival times during the storm, nor any evidence for periodicity in the source's activity between observations. The burst storm shows a steep burst energy distribution (power-law index $\alpha = 2.39\pm0.12$) and a bi-modal wait-time distribution, with log-normal means of 0.94$^{+0.07}_{-0.06}$ s and 23.61$^{+3.06}_{-2.71}$ s. We attribute these peaks in the wait-time distribution to a characteristic event timescale and pseudo-Poisson burst rate, respectively. The secondary wait-time peak at $\sim1$ s is $\sim50\times$ longer than the $\sim30$ ms timescale seen for both FRB 20121102A and FRB 20201124A -- potentially indicating a larger emission region, or slower burst propagation through this region. At the same time, FRB 20200120E shows, on average, order-of-magnitude lower burst durations and luminosities compared with FRB 20121102A and FRB 20201124A. Lastly, in contrast to FRB 20121102A, which has observed dispersion measure (DM) variations of $\Delta{\rm DM} >1$ pc cm$^{-3}$ on month-to-year timescales, we determine that the DM of FRB 20200120E has remained stable ($\Delta{\rm DM} <0.15$ pc cm$^{-3}$) between measurements separated by $>10$ months. Overall, the observational characteristics of FRB 20200120E deviate quantitatively from other active repeaters, but it is unclear whether it is qualitatively a different type of source.

India reached a major milestone in the area of space astronomy with the successful launch and post-launch operations of its first space observatory, AstroSat. The success of this space observatory and the lessons learned must be utilized effectively to enlarge the footprint of Indian space astronomy in the international scene. In response to a call for proposals by the Indian Space Research Organisation, a detailed proposal for a next generation UV-optical mission, the INdian Spectroscopic and Imaging Space Telescope (INSIST) was submitted. Combining a large focal area with a simple and efficient optical design, INSIST is expected to produce HST-quality imaging and moderate resolution spectra of astronomical sources. The main science drivers for this mission span a wide range of topics, starting from evolution of galaxies in groups and clusters, chemo-dynamics and demographics of the nearby universe, stellar systems with accretions, to stars with planetary systems, to cosmology near and far. The proposal was awarded seed funding and has completed two years of pre-project phase. An overview of this proposed mission is presented here along with the current status.

We do a morphological, kinematic and chemical analysis of the disrupting cluster UBC 274 (2.5 Gyr, $d=1778$ pc) to study its global properties. We use HDBSCAN to obtain a new membership list up to 50 pc from its centre and up to magnitude $G=19$ using Gaia EDR3 data. We use high resolution and high signal-to-noise spectra to obtain atmospheric parameters of 6 giants and subgiants, and individual abundances of 18 chemical species. The cluster has a highly eccentric (0.93) component, tilted $\sim$10 deg with respect to the plane of the Galaxy, which is morphologically compatible with the result of a test-particle simulation of a disrupting cluster. Our abundance analysis shows that the cluster has a subsolar metallicity of [Fe/H]$=-0.08\pm0.02$. Its chemical pattern is compatible with that of Ruprecht 147, of similar age but located closer to the Sun, with the remarkable exception of neutron-capture elements, which present an overabundance of $[n\mathrm{/Fe]}\sim0.1$. The cluster's elongated morphology is associated with the internal part of its tidal tail, following the expected dynamical process of disruption. We find a significant sign of mass segregation where the most massive stars appear 1.5 times more concentrated than other stars. The cluster's overabundance of neutron-capture elements can be related to the metallicity dependence of the neutron-capture yields due to the secondary nature of these elements, predicted by some models. UBC 274 presents a high chemical homogeneity at the level of $0.03$ dex in the sampled region of its tidal tails.

CARMENES is a next-generation instrument being built by a consortium of German and Spanish institutions to carry out a survey of 300 M-type dwarf stars with the goal of detecting exoearths by radial-velocity measurements. To collect relevant information from different on-line catalogues for a given sample of 209 binary or multiple star systems, formed by F, G or K primary star and an M-dwarf (or late-K) companion. To prove if the pair is indeed a physical pair, to obtain different metallicity calibrations in K-band with these binary systems. The data compilation from every star has been done searching in catalogues in VizieR and the literature. In addition, physical pair checking has been done studying the collected proper motions from both stars (primary and secondary) and using two tools from the Virtual Observatory: Aladin and TopCat. From a list of suitable systems, two different types of calibrations had been obtained: spectroscopic and photometric. In order to determine these calibrations, we have considered that metallicity from the primary star, determined by the CARMENES UCM research group, is equal to the secondary star.

The estimation of the binary fraction of hot subdwarfs is key to shed light on the different evolution scenarios proposed to explain the loss of the hydrogen envelope during the red giant branch phase. In this paper we analyse the spectral energy distribution of the hot subdwarfs included in a recent and comprehensive catalogue with the aim of identifying companions. Our methodology shows a performance superior to the photometric criteria used in that study, identifying 202 objects wrongly classified as binaries according to their spectral energy distributions, and finding 269 new binaries. Out of an initial sample of 3186 objects, we classified 2469 as single and 615 as binary hot subdwarfs. The rest of the objects (102) were not classified because of their inadequate spectral energy distribution fitting due, in turn, to poor quality photometry. Effective temperatures, luminosities and radii were computed for 192 singles and 42 binaries. They, in particular the binary sample, constitute an excellent dataset to further perform a more careful spectroscopic analysis that could provide detailed values for the chemical composition, masses, ages, rotation properties or reflection effects for the shortest-period systems. The results obtained in this paper will be used as a reference for a forthcoming work where we aim to generalize binary and single hot subdwarf classification using Artificial Intelligence-based techniques.

Parker Solar Probe (PSP) has shown that the solar wind in the inner heliosphere is characterized by the quasi omni-presence of magnetic switchbacks ("switchback" hereinafter), local backward-bends of magnetic field lines. Switchbacks also tend to come in patches, with a large-scale modulation that appears to have a spatial scale size comparable to supergranulation on the Sun. Here we inspect data from the first ten encounters of PSP focusing on different time intervals when clear switchback patches were observed by PSP. We show that the switchbacks modulation, on a timescale of several hours, seems to be independent of whether PSP is near perihelion, when it rapidly traverses large swaths of longitude remaining at the same heliocentric distance, or near the radial-scan part of its orbit, when PSP hovers over the same longitude on the Sun while rapidly moving radially inwards or outwards. This implies that switchback patches must also have an intrinsically temporal modulation most probably originating at the Sun. Between two consecutive patches, the magnetic field is usually very quiescent with weak fluctuations. We compare various parameters between the quiescent intervals and the switchback intervals. The results show that the quiescent intervals are typically less Alfv\'enic than switchback intervals, and the magnetic power spectrum is usually shallower in quiescent intervals. We propose that the temporal modulation of switchback patches may be related to the "breathing" of emerging flux that appears in images as the formation of "bubbles" below prominences in the Hinode/SOT observations.

It is already accepted that Be stars are surrounded by circumstellar envelopes, which are mostly compatible with a disc geometry in Keplerian rotation. We aim to obtain a more complete characterisation of the properties of the circumstellar environment of Be stars that helps to constrain the theoretical models of the Be phenomenon. We present near-infrared, medium-resolution spectra of a sample of galactic Be stars with different spectral subtypes and luminosity classes. We measure different parameters of the hydrogen recombination lines from the Paschen, Brackett, Pfund, and Humphreys series, and use them to diagnose physical conditions in the circumstellar environment. We analysed the equivalent-width (EW) ratio between Br$\alpha$ and Br$\gamma$ lines and different diagrams of flux ratios. We also identify lines from He I, C I, N I, O I, Na I, Mg I, Mg II, Si I, Fe I, and Fe II. Analysing the EW measurements of particular He I, Mg II, Fe I, Fe II and O I lines, we find that for some lines they correlate with the spectral type of the star. Particularly, the emission of the O I~$\lambda\,1.3168\,\mu$m line decreases towards the later spectral types. We present an atlas of 22 Be stars, that covers a wide infrared (IR) spectral range with quasi-simultaneous observations. From a detailed analysis, we define new complementary criteria to Mennickent's classification of Be stars according to their disc opacity. Some objects in our sample present compact thick envelopes, while in others the envelope is extended and optically thin. The correlation between the full widths at half maximum (FWHM) and the peak separation ($\Delta \mathrm{V}$) versus $V\,\sin\,i$ for the Br10, Br$\delta$, and Hu14 lines reveals that the broadening mechanism is rotational. The Ly$\beta$ fluorescence is a key mechanism to explain the intensity of the emission of Mg II and O I lines.

The vertical shear instability (VSI) is a robust phenomenon in irradiated protoplanetary disks (PPDs). The majority of previous numerical simulations have focused on the turbulent properties of its saturated state. However, the saturation of the VSI manifests as large-scale coherent radially travelling inertial waves. In this paper, we study inertial-wave-disk interactions and their impact on VSI saturation. Inertial-wave linear theory is developed and applied to a representative global 2D simulation using the Athena++ code. It is found that the VSI saturates by separating the disk into several radial wave zones roughly demarcated by corotation resonances (turning points); this structure also manifests in modest radial variations in the vertical turbulence strength. Future numerical work should employ large radial domains to accommodate this radial structure of the VSI, while concurrently adopting sufficiently fine resolutions to resolve the parametric instability that attacks the saturated VSI inertial waves.

The study of short-term variability properties in AGN jets has the potential to shed light on their particle acceleration and emission mechanisms. We report results from a four-day coordinated multi-wavelength campaign on the highly-peaked blazar (HBL) Mkn 421 in 2019 January. We obtained X-ray data from AstroSAT, BVRI photometry with the Whole Earth Blazar Telescope (WEBT), and TeV data from FACT to explore short-term multi-wavelength variability in this HBL. The X-ray continuum is rapidly variable on time-scales of tens of ks. Fractional variability amplitude increases with energy across the synchrotron hump, consistent with previous studies; we interpret this observation in the context of a model with multiple cells whose emission spectra contain cutoffs that follow a power-law distribution. We also performed time-averaged and time-resolved (time-scales of 6 ks) spectral fits; a broken power-law model fits all spectra well; time-resolved spectral fitting reveals the usual hardening when brightening behaviour. Intra-X-ray cross correlations yield evidence for the 0.6-0.8 keV band to likely lead the other bands by an average of 4.6 +- 2.6 ks, but only during the first half of the observation. The source displayed minimal night-to-night variability at all wavebands thus precluding significant interband correlations during our campaign. The broadband SED is modeled well with a standard one-zone leptonic model, yielding jet parameters consistent with those obtained from previous SEDs of this source.

We study the possibility that the Milky Way's cool stellar disc includes mergers with ancient stars. Galaxies are understood to form in a hierarchical manner, where smaller (proto-)galaxies merge into larger ones. Stars in galaxies, like the Milky Way, contain in their motions and elemental abundances tracers of past events and can be used to disentangle merger remnants from stars that formed in the main galaxy. The merger history of the Milky Way is generally understood to be particularly easy to study in the stellar halo. The advent of the ESA astrometric satellite Gaia has enabled the detection of completely new structures in the halo such as the Gaia-Enceladus-Sausage. However, simulations also show that mergers may be important for the build-up of the cool stellar disks. Combining elemental abundances for 100 giant branch stars from APOGEE DR17 and astrometric data from Gaia we use elemental abundance ratios to find an hitherto unknown, old stellar component in the cool stellar disk in the Milky Way. We further identify a small sample of RR Lyrae variables with disk kinematics that also show the same chemical signature as the accreted red giant stars in the disk. These stars allows us to date the stars in the accreted component. We find that they are exclusively old.

We investigate the inclusion of clustering maps in a weak lensing Minkowski functional (MF) analysis of DES-like and LSST-like simulations to constrain cosmological parameters. The standard 3x2pt approach to lensing and clustering data uses two-point correlations as its primary statistic; MFs, morphological statistics describing the shape of matter fields, provide additional information for non-Gaussian fields. Previous analyses have studied MFs of lensing convergence maps; in this project we explore their simultaneous application to clustering maps. We employ a simplified linear galaxy bias model, and using a curved sky measurement and Monte Carlo Markov Chain (MCMC) sampling process for parameter inference, we find that MFs do not yield any information in the $\Omega_{\rm m}$ - $\sigma_8$ plane not already generated by a 3x2pt analysis. However, we expect that MFs should improve constraining power when nonlinear baryonic and other small-scale effects are taken into account. As with a 3x2pt analysis, we find a significant improvement to constraints when adding clustering data to MF-only and MF$+C_\ell$ shear measurements, and strongly recommend future higher order statistics be measured from both convergence and clustering maps.

Based on recently-taken and archival HARPS, FEROS and HIRES radial velocities (RVs), we present evidence for a new planet orbiting the first ascent red giant star HD33142 (with an improved mass estimate of 1.52$\pm$0.03 M$_\odot$), already known to host two planets. We confirm the Jovian mass planets HD33142 b and c with periods of $P_{\rm b}$ = 330.0$_{-0.4}^{+0.4}$ d and $P_{\rm c}$ = 810.2$_{-4.2}^{+3.8}$ d and minimum dynamical masses of $m_{\rm b}\sin{i}$ = 1.26$_{-0.05}^{+0.05}$ M$_{\rm Jup}$ and $m_{\rm c}\sin{i}$ = 0.89$_{-0.05}^{+0.06}$ M$_{\rm Jup}$. Furthermore, our periodogram analysis of the precise RVs shows strong evidence for a short-period Doppler signal in the residuals of a two-planet Keplerian fit, which we interpret as a third, Saturn-mass planet with $m_\mathrm{d}\sin{i}$ = 0.20$_{-0.03}^{+0.02}$ M$_{\rm Jup}$ on a close-in orbit with an orbital period of $P_{\rm d}$ =89.9$_{-0.1}^{+0.1}$ d. We study the dynamical behavior of the three-planet system configurations with an N-body integration scheme, finding it long-term stable with the planets alternating between low and moderate eccentricities episodes. We also performed N-body simulations, including stellar evolution and second-order dynamical effects such as planet-stellar tides and stellar mass-loss on the way to the white dwarf phase. We find that planets HD33142 b, c and d are likely to be engulfed near the tip of the red giant branch phase due to tidal migration. These results make the HD33142 system an essential benchmark for the planet population statistics of the multiple-planet systems found around evolved stars.

All neutron star progenitors in neutron-star High-Mass X-ray Binaries (NS HMXBs) undergo a supernova event that may lead to a significant natal kick impacting the motion of the whole binary system. The space observatory Gaia performs a deep optical survey with exquisite astrometric accuracy, for both position and proper motions, that can be used to study natal kicks in NS HMXBs. We aim to survey the observed Galactic NS HMXB population and to quantify the magnitude of the kick imparted onto their NSs, and to highlight any possible differences arising in between the various HMXB types. We perform a census of Galactic NS HMXBs and cross-match existing detections in X-rays, optical and infrared with the Gaia Early Data Release 3 database. We retrieve their parallaxes, proper motions, and radial velocities (when available), and perform a selection based on the quality of the parallax measurement. We then compute their peculiar velocities with respect to the rotating reference frame of the Milky Way, and including their respective masses and periods, we estimate their kick velocities through Markov Chain Monte Carlo simulations of the orbit undergoing a supernova event. We infer the posterior kick distributions of 35 NS HMXBs. After an inconclusive attempt at characterising the kick distributions with Maxwellian statistics, we find that the observed NS kicks are best reproduced by a Gamma distribution of mean $116^{+18}_{-15}$km.s$^{-1}$. We note that supergiant systems tend to have higher kick velocities than Be High-Mass X-ray Binaries. The peculiar velocity versus non-degenerate companion mass plane hints at a similar trend, supergiant systems having a higher peculiar velocity independently of their companion mass.

A significant fraction of massive stars move at speed through the interstellar medium of galaxies. After their death as core collapse supernovae, a possible final evolutionary state is that of a fast rotating magnetised neutron star, shaping its circumstellar medium into a pulsar wind nebula. Understanding the properties of pulsar wind nebulae requires knowledge of the evolutionary history of their massive progenitors. Using 2.5D magnetohydrodynamical simulations, we demonstrate that, in the context of a runaway high mass red supergiant supernova progenitor, the morphology of its subsequent pulsar wind nebula is strongly affected by the wind of the defunct progenitor star preshaping the stellar surroundings throughout its entire past life. In particular, pulsar wind nebulae of obscured runaway massive stars harbour asymmetries function of the morphology of the progenitors wind blown cavity, inducing projected asymmetric up down synchrotron emission.

The turbulence driven by gravitational instabilities (GIs) can amplify magnetic fields in massive gaseous disks. This GI dynamo may appear in young circumstellar disks, whose weak ionization challenges other amplification routes, as well as in active galactic nuclei. Although regarded as a large-scale dynamo, only local numerical simulations have yet described its kinematic regime. We study the GI dynamo in global magnetohydrodynamic (MHD) models of accretion disks, focusing on its kinematic phase. We perform resistive MHD simulations with the Pluto code for different radiative cooling times and electrical resistivities. A weak magnetic field seeds the dynamo, and we adopt mean-field and heuristic models to capture its essence. We recover the same induction process leading to magnetic field amplification as previously identified in local simulations. The dynamo is however global in nature, connecting distant annuli of the disk via a large-scale dynamo mode of a fixed growth rate. This large-scale amplification can be described by a mean-field model that does not rely on conventional alpha-Omega effects. When varying the disk parameters we find an optimal resistivity facilitating magnetic amplification, whose magnetic Reynolds number Rm < 10 is substantially smaller than in local simulations. Unlike local simulations, we find an optimal cooling rate and the existence of global oscillating dynamo modes. The nonlinear saturation of the dynamo puts the disk in a strongly magnetized turbulent state on the margins of the effective range of GI. In our simulations the accretion power eventually exceeds the threshold required by local thermal balance against cooling, leaving the long-term nonlinear outcome of the GI dynamo uncertain.

Non-uniformity of the solar atmosphere along with the presence of non-adiabatic processes such as radiation cooling and unspecified heating can significantly affect the dynamics and properties of magnetoacoustic (MA) waves. To address the co-influence of these factors on the dispersion properties of MA waves, we considered a single magnetic slab composed of the thermally active plasma. Using the perturbation theory, we obtained a differential equation that determines the dynamics of the two-dimensional perturbations. Applying the assumption of strong magnetic structuring, we derived the dispersion relations for the sausage and kink MA modes. The numerical solution of the dispersion relations for the coronal conditions was performed to investigate the interplay between the non-uniformity and the thermal misbalance. For the heating scenario considered, it was obtained that the phase speed of both the sausage and kink slow MA waves is highly affected by the thermal misbalance in the long wavelength limit. The obtained characteristic timescales of the slow waves dissipation coincide with the periods of waves observed in the corona. Simultaneously, the phase speed of the fast waves is not affected by the thermal misbalance. The geometry of the magnetic structure still remains the main dispersion mechanism for the fast waves. Our estimation reveals that dissipation of the fast waves is weaker than dissipation of the slow waves in the coronal conditions. The obtained results are of importance for using the magnetoacoustic waves not only as a tool for estimating plasma parameters, but also as a tool for estimating the non-adiabatic processes.

We have obtained column density maps for an unbiased sample of 120 molecular clouds in the third quadrant of the Milky Way mid-plane (b$\le |5|^{\circ}$) within the galactic longitude range from 195$^{\circ}$ to 225$^{\circ}$, using the high sensitivity $^{12}$CO and $^{13}$CO ($J=1-0$) data from the Milky Way Imaging Scroll Painting (MWISP) project. The probability density functions of the molecular hydrogen column density of the clouds, N-PDFs, are fitted with both log-normal (LN) function and log-normal plus power-law (LN+PL) function. The molecular clouds are classified into three categories according to their shapes of N-PDFs, i.e., LN, LN+PL, and UN (unclear), respectively. About 72\% of the molecular clouds fall into the LN category, while 18\% and 10\% into the LN+PL and UN categories, respectively. A power-law scaling relation, $\sigma_s\propto N_{H_2}^{0.44}$, exists between the width of the N-PDF, $\sigma_s$, and the average column density, $N_{H_2}$, of the molecular clouds. However, $\sigma_s$ shows no correlation with the mass of the clouds. A correlation is found between the dispersion of normalized column density, $\sigma_{N/\rm <N>}$, and the sonic Mach number, $\mathcal{M}$, of molecular clouds. Overall, as predicted by numerical simulations, the N-PDFs of the molecular clouds with active star formation activity tend to have N-PDFs with power-law high-density tails.

A comprehensive study of the co-evolution of globular cluster systems (GCS) in galaxies requires the ability to model both the large scale dynamics (0.01 - 10 kpc) regulating their orbital evolution, and the small scale dynamics (sub-pc - AU) regulating the internal dynamics of each globular cluster (GC). In this work we present a novel method that combine semi-analytic models of GCS with fully self-consistent Monte Carlo models to simultaneously evolve large GCSs. We use the population synthesis code MASinGa and the MOCCA-Survey Database I to create synthetic GC populations aimed at representing the observed features of GCs in the Milky Way (MW) and Andromeda (M31). Our procedure enables us to recover the spatial and mass distribution of GCs in such galaxies, and to constrain the amount of mass that GCs left either in the halo as dispersed debris, or in the galactic centre, where they can contribute to the formation of a nuclear star cluster (NSC) and can bring stellar and possibly intermediate mass black holes there. The final masses reported by our simulations are of a few order of magnitudes smaller than the observed values. These differences show that mass build-up of a NSC and central BHs in galaxies like MW and M31 cannot be solely explained by the infalling GC scenario. This build-up is likely to depend on the interplay between interactions and mergers of infalling GCs and gas. The latter can contribute to both in-situ star formation in the NSC and growth of the central BH.

Kepler's short-period exoplanet population has revealed evolutionary features such as the Radius Valley and the Hot Neptune desert that are likely sculpted by atmospheric loss over time. These findings suggest that the primordial planet population is different from the Gyr-old Kepler population, and motivates exoplanet searches around young stars. Here, we present pterodactyls , a data reduction pipeline specifically built to address the challenges in discovering exoplanets around young stars and to work with TESS Primary Mission 30-min cadence photometry, since most young stars were not pre-selected TESS 2-min cadence targets. pterodactyls builds on publicly available and tested tools in order to extract, detrend, search, and vet transiting young planet candidates. We search five clusters with known transiting planets: Tucana-Horologium Association, IC 2602, Upper Centaurus Lupus, Ursa Major and Pisces Eridani. We show that pterodactyls recovers seven out of the eight confirmed planets and one out of the two planet candidates, most of which were initially detected in 2-min cadence data. For these clusters, we conduct injection-recovery tests to characterize our detection efficiency, and compute an intrinsic planet occurrence rate of 49+-20% for sub-Neptunes and Neptunes (1.8-6 Re) within 12.5 days, which is higher than Kepler's Gyr-old occurrence rates of 6.8+-0.3%. This potentially implies that these planets have shrunk with time due to atmospheric mass loss. However, a proper assessment of the occurrence of transiting young planets will require a larger sample unbiased to planets already detected. As such, pterodactyls will be used in future work to search and vet for planet candidates in nearby clusters and moving groups.

The neutron star low mass X-ray binary (LMXB) AX J1745.6-2901 was detected an anomalously fast decrease of orbital period. The decreasing rate of orbital period exceeds the contribution of all processes extracting angular momentum from the binary star in standard model. Using SCENARIO MACHINE code we conducted a population synthesis study of X-ray novae with neutron stars to investigate a possible formation and evolution of such binaries. Such close LMXBs should experience a preceding common envelope stage, in which the magnetic fields of the low mass main-sequence donor stars can be dramatically amplified. Our calculations show that the magnetic stellar wind of the optical companion can efficiently extract angular momentum from the binary systems, and produce the observed orbital-period derivatives of AX J1745.6-2901 and black hole LMXBs. The estimated values of the required magnetic field induction are following: $B_\textrm{d}\approx 400$ G (AX~J1745.6-2901), $B_\textrm{d}\approx 1500$ G (KV UMa), $B_\textrm{d}\approx 400$ G (A0620-00), $B_\textrm{d}\approx 1800$ G (Nova Muscae). We successfully reproduced the current observational abundance of such anomalous neutron star X-ray novae, and computed the appropriate value of the parameter of magnetic braking $\lambda_\textrm{MSW}$ ($0.8-0.6$ for Roche lobe filling stars and $0.4-0.15$ for binaries with partial Roche lobe filling).

We calculate how primordial anisotropies in the background space-time affect the evolution of cosmological perturbations for bouncing alternatives to inflation, like ekpyrosis and the matter bounce scenario. We find that the leading order effect of anisotropies in the contracting phase of the universe is to induce anisotropies in the cosmic microwave background with a very concrete form: a scale-invariant quadrupolar angular distribution. Sub-leading effects are the generation of higher-order moments in the angular distribution, as well as cross-correlations between scalar and tensor modes. We also find that observational constraints from the cosmic microwave background on the quadrupole moment provide strong bounds on allowed anisotropies for bouncing alternatives to inflation that are significantly more constraining than the bounds previously obtained using scaling arguments based on the conjectured Belinski-Khalatnikov-Lifshitz instability.

We carry on a general study on non--static spherically symmetric fluids admitting a conformal Killing vector (CKV). Several families of exact analytical solutions are found for different choices of the CKV, in both, the dissipative and the adiabatic regime. To specify the solutions, besides the fulfillment of the junction conditions on the boundary of the fluid distribution, different conditions are imposed, such as vanishing complexity factor and quasi--homologous evolution. A detailed analysis of the obtained solutions, its prospective applications to astrophysical scenarios, as well as alternative approaches to obtain new solutions, are discussed.

The swampland conjecture known as Festina Lente (FL) imposes a lower bound on the mass of all charged particles in a quasi-de Sitter space. In this paper, we propose the aFL (axionic Festina Lente) bound, an extension of FL to axion-like particles arising from type II string theory. We find that the product of the instanton action and the axion decay constant is bounded from below by the vacuum energy. This is achieved indirectly, using dimensional reduction on Calabi-Yau threefolds, and translating the FL result for dipoles into a purely geometric bound. We discuss axionic black holes evolution, and aFL constraints on Euclidean wormholes, showing that the gravitational arguments leading to the FL bound for U$(1)$ charged particles cannot be directly applied to axions. Moreover, we discuss phenomenological implications of the aFL bound, including constraints on string inflation models and the axion-photon coupling via kinetic mixing.

The primary alcohol $n$-propanol (i.e., $normal$-propanol or propan-1-ol; C$_3$H$_7$OH) occurs in five different conformers: $Ga$, $Gg$, $Gg'$, $Aa$, and $Ag$. All rotational spectra of the three conformers of the $G$ family are well described, making astronomical search of their spectroscopic signatures possible, as opposed to those of the $Aa$ and $Ag$ conformers. Our goal is to facilitate the astronomical detection of $Aa$ and $Ag$ conformers of $n$-propanol by characterizing their rotational spectra. We recorded the rotational spectra of $n$-propanol in the frequency domain of 18$-$505\,GHz.Additional double-modulation double-resonance (DM-DR) measurements were performed, more specifically with the goal to unambiguously assign weak transitions of the $Aa$ conformer and to verify assignments of the $Ag$ conformer. We derived a spectroscopic quantum mechanical model with experimental accuracy (with $J_\textrm{max}=70$ and $K_{a,\textrm{max}}=6$) for $Aa$ $n$-propanol. Furthermore, we unambiguously assigned transitions (with $J_\textrm{max}=69$ and $K_{a,\textrm{max}}=9$) of $Ag$ $n$-propanol; in doing so, we prove the existence of two tunneling states, $Ag^+$ and $Ag^-$. The astronomical search of all five conformers of $n$-propanol is now possible via their rotational signatures. These are applied in a companion article on the detection of $n$-propanol toward the hot molecular core Sgr B2(N2).

We compute the leading order non-Gaussianity, i.e., the bispectrum, of the tensor perturbation in the general $\alpha$-vacuum on de Sitter space in general relativity. In addition to the well-known Bunch-Davies (BD) vacuum, there exits an infinite number of de Sitter invariant vacua represented by a real parameter $\alpha$ and a phase $\phi$, with $\alpha=0$ being the BD vacuum. They are called $\alpha$-vacua. In the standard slow-roll inflation, as de Sitter invariance no longer applies, the $\alpha$-vacua lose its relevance in the rigorous sense. Nevertheless, if we assume that the parameter $\alpha$ is only weakly dependent on the wavenumber with an appropriate UV cutoff, we may consider pseudo-$\alpha$-vacua. In the case of false vacuum inflation where the background spacetime is pure de Sitter, a non-trivial (non-BD) $\alpha$-vacuum could indeed be realized. We find an intriguing result that the bispectrum may be exponentially enhanced to be detectable by observation even if the spectrum is too small to be detected.

We study possible effects of non-local gravity corrections on the recent discovery by the IceCube collaboration reporting high-energy neutrino flux detected at energies of order PeV. Considering the 4-dimensional operator $\sim y_{\alpha \chi}\bar{{L_{{\alpha}}}}\, H\, \chi$, it is possible to explain both the IceCube neutrino rate and the abundance of Dark Matter, provided that non-local corrections are present in the cosmological background. Furthermore, the mechanism could constitute a natural way to address the $H_0$ tension issue.

The presence of spacetime singularities in physically relevant solutions of the Einstein Equations is normally interpreted as a symptom of the breakdown of classical general relativity at very high densities/curvatures. However, despite significant efforts in the past decades, we do not have yet any robust theoretical framework to solve the problem of spacetime singularities. In this context, the past few years have seen an increasing interest in the study of phenomenological scenarios to describe singularity-free black holes, gravitational collapses, and cosmological models. In the present work, we consider the recent proposal by Mazza, Franzin & Liberati for a rotating regular black hole and we measure their regularization parameter $l$ from the available X-ray and gravitational wave black hole data. For $l = 0$, we recover the singular Kerr solution of general relativity, while for $l \neq 0$ we can have a regular black hole or a regular wormhole. Our analysis shows that the available data are consistent with a vanishing regularization parameter $l$ and we can constrain its value. From a NuSTAR spectrum of the Galactic black hole in EXO 1846-031, we find $l/M < 0.49$ (90% CL). From the gravitational wave event GW190707A, we find $l/M < 0.72$ (90% CL).

Pulsar timing array experiments have recently reported strong evidence for a common-spectrum stochastic process with a strain spectral index consistent with that expected of a nanohertz-frequency gravitational wave background, but with negligible yet non-zero evidence for spatial correlations required for a definitive detection. However, it was pointed out by the Parkes Pulsar Timing Array (PPTA) collaboration that the same models used in recent analyses resulted in strong evidence for a common-spectrum process in simulations where none is present. In this work, we introduce a methodology to distinguish pulsar power spectra with the same amplitude from noise power spectra of similar but distinct amplitudes. The former is the signature of a spatially uncorrelated pulsar term of a nanohertz gravitational wave background, whereas the latter could represent ensemble pulsar noise properties. We test the methodology on simulated data sets. We find that the reported common process in PPTA pulsars is indeed consistent with the spectral feature of a pulsar term. We recommend this methodology as one of the validity tests that the real astrophysical and cosmological backgrounds should pass, as well as for inferences about the spatially-uncorrelated component of the background.

We provide rigorous theoretical bounds for Anderson acceleration (AA) that allow for efficient approximate calculations of the residual, which reduce computational time and memory storage while maintaining convergence. Specifically, we propose a reduced variant of AA, which consists in projecting the least squares to compute the Anderson mixing onto a subspace of reduced dimension. The dimensionality of this subspace adapts dynamically at each iteration as prescribed by computable heuristic quantities guided by the theoretical error bounds. The use of the heuristic to monitor the error introduced by approximate calculations, combined with the check on monotonicity of the convergence, ensures the convergence of the numerical scheme within a prescribed tolerance threshold on the residual. We numerically assess the performance of AA with approximate calculations on: (i) linear deterministic fixed-point iterations arising from the Richardson's scheme to solve linear systems with open-source benchmark matrices with various preconditioners and (ii) non-linear deterministic fixed-point iterations arising from non-linear time-dependent Boltzmann equations.

In this paper, we consider the problem of reconstructing a galaxy's stellar population-kinematic distribution function from optical integral field unit measurements. These quantities are connected via a high-dimensional integral equation. To solve this problem, we propose a projected Nesterov-Kaczmarz reconstruction (PNKR) method, which efficiently leverages the problem structure and incorporates physical prior information such as smoothness and non-negativity constraints. To test the performance of our reconstruction approach, we apply it to a dataset simulated from a known ground truth density, and validate it by comparing our recoveries to those obtained by the widely used pPXF software.

We use the orbital motion of the star S2 around the supermassive black hole at the center of the Galaxy to narrow the allowed range for the mass of an ultralight boson. It is well known that ultralight bosons form a solitonic dark matter core in the innermost part of the halo. The scale length of such a soliton depends on the inverse of the mass of the boson. On the other hand, the orbital motion of stars in the Galactic center depends on the distribution of matter whether be it baryonic or dark. Thus, we predict that future astrometric and spectroscopic observations of S2 will place an upper limit on the mass of the boson which in fact, once complementary constraints are considered, will help to restrict the allowed range of the boson mass.