Miracle-dz/UniFAR-FTUs huggingface dataset:
Habitability of terrestrial-mass planets in the HZ of M Dwarfs – I. H/He-dominated atmospheres

The ubiquity of M dwarfs, combined with the relative ease of detecting terrestrial-mass planets around them, has made them prime targets for finding and characterising planets in the "Habitable Zone" (HZ). However, Kepler finds that terrestrial-mass exoplanets are often born with voluminous H/He envelopes, comprising mass-fractions ($M_{env}/M_{core}$) $\gtrsim 1$%. If these planets retain such envelopes over Gyr timescales, they will not be "habitable" even within the HZ. Given the strong X-ray/UV fluxes of M dwarfs, we study whether sufficient envelope mass can be photoevaporated away for these planets to become habitable. We improve upon previous work by using hydrodynamic models that account for radiative cooling as well as the transition from hydrodynamic to ballistic escape. Adopting a template active M dwarf XUV spectrum, including stellar evolution, and considering both evaporation and thermal evolution, we show that: (1) the mass-loss is (considerably) lower than previous estimates that use an "energy-limited" formalism and ignore the transition to Jeans escape, (2) at the inner edge of the HZ, planets with core mass $\lesssim 0.9$ M$_\oplus$, can lose enough H/He to become habitable if their initial envelope mass-fraction is $\sim$1%, (3) at the outer edge of the HZ, evaporation cannot remove a $\sim$1% H/He envelope even from cores down to 0.8 M$_\oplus$. Thus, if planets form with bulky H/He envelopes, only those with low-mass cores may eventually be habitable. Cores $\gtrsim$ 1 M$_\oplus$, with $\gtrsim$1% natal H/He envelopes, will not be habitable in the HZ of M dwarfs.
Constraining the Milky Way dark matter density profile with gamma-rays with Fermi-LAT

We study the abilities of the Fermi–LAT instrument on board of the Fermi mission to simultaneously constrain the Milky Way dark matter density profile and some dark matter particle properties, as annihilation cross section, mass and branching ratio into dominant annihilation channels. A single dark matter density profile is commonly assumed to determine the capabilities of gamma-ray experiments to extract dark matter properties or to set limits on them. However, our knowledge of the Milky Way halo is far from perfect, and thus in general, the obtained results are too optimistic. Here, we study the effect these astrophysical uncertainties would have on the determination of dark matter particle properties and conversely, we show how gamma-ray searches could also be used to learn about the structure of the Milky Way halo, as a complementary tool to other type of observational data that study the gravitational effect caused by the presence of dark matter. In addition, we also show how these results would improve if external information on the annihilation cross section and on the local dark matter density were included and compare our results with the predictions from numerical simulations.
REVISITING THE SHORT-TERM X-RAY SPECTRAL VARIABILITY OF NGC 4151 WITH CHANDRA

We present new X-ray spectral data for the Seyfert 1 nucleus in NGC 4151 observed with Chandra for ∼200 ks. A significant ACIS pileup is present, resulting in a nonlinear count rate variation during the observation. With pileup corrected spectral fitting, we are able to recover the spectral parameters and find consistency with those derived from unpiled events in the ACIS readout streak and outer region from the bright nucleus. The absorption corrected 2–10 keV flux of the nucleus varied between 6 × 10−11 erg s−1 cm−2 and 10−10 erg s−1 cm−2 (L2–10 keV ∼ 1.3–2.1 × 1042 erg s−1). Similar to earlier Chandra studies of NGC 4151 at a historical low state, the photon indices derived from the same absorbed power-law model are Γ ∼ 0.7–0.9. However, we show that Γ is highly dependent on the adopted spectral models. Fitting the power-law continuum with a Compton reflection component gives Γ ∼ 1.1. By including passage of non-uniform X-ray obscuring clouds, we can reproduce the apparent flat spectral states with Γ ∼ 1.7, typical for Seyfert 1 active galactic nuclei. The same model also fits the hard spectra from previous ASCA “long look” observation of NGC 4151 in the lowest flux state. The spectral variability during our observation can be interpreted as variations in intrinsic soft continuum flux relative to a Compton reflection component that is from distant cold material and constant on short timescale, or variations of partially covering absorber in the line of sight toward the nucleus. An ionized absorber model with ionization parameter log ξ ∼ 0.8–1.1 can also fit the low-resolution ACIS spectra. If the partial covering model is correct, adopting a black hole mass M☉ we constrain the distance of the obscuring cloud from the central black hole to be r ≲ 9 lt-day, consistent with the size of the broad emission line region of NGC 4151 from optical reverberation mapping.
Observations of 6–200 μm emission of the Ophiuchus cloud LDN 1688

We examine two positions, ON1 and ON2, within the Ophiuchus cloud LDN 1688 using observations made with the ISOPHOT instrument aboard the ISO satellite. The data include mid-IR spectra (~6-12{\mu}m) and several photometric bands up to 200{\mu}m. The data probe the emission from molecular PAH-type species, transiently-heated Very Small Grains (VSGs), and large classical dust grains. We compare the observations to earlier studies, especially those carried out towards an isolated translucent cloud in Chamaeleon (Paper I). The spectra towards the two LDN 1688 positions are very similar to each other, in spite of position ON1 having a larger column density and probably being subjected to a stronger radiation field. The ratios of the mid-IR features are similar to those found in other diffuse and translucent clouds. Compared to paper I, the 7.7/11.3{\mu}m band ratios are lower, ~2.0, at both LDN 1688 positions. A continuum is detected in the ~10{\mu}m region. This is stronger towards the position ON1 but still lower than on any of the sightlines in Paper I. The far-infrared opacities are higher than for diffuse medium. The value of the position ON2, {\tau}200/N(H) = 3.9 x 10^{-25} cm^2/H, is twice the value found for ON1. The radiation field of LDN 1688 is dominated by the two embedded B type double stars, {\rho} Oph AB and HD 147889, with an additional contribution from the Upper Sco OB association. The strong heating is reflected in the high colour temperature, ~24 K, of the large grain emission. Radiative transfer modelling confirms a high level of the radiation field and points to an increased abundance of PAH grains. However, when the hardening of the radiation field caused by the local B-stars is taken into account, the observations can be fitted with almost no change to the standard dust models. However, all the examined models underestimate the level of the mid-IR continuum.
Comprehensive study of a z = 2.35 DLA Galaxy: mass, metallicity, age, morphology and SFR from HST and VLT

We present a detailed study of the emission from a z = 2:35 galaxy that causes damped Lyman- absorption in the spectrum of the background QSO, SDSS J 2222 0946. We present the results of extensive analyses of the stellar continuum covering the rest frame optical-UV regime based on broad-band HST imaging, and of spectroscopy from VLT/X-Shooter of the strong emission lines: Ly , [OII], [OIII], [NII], H and H . We compare the metallicity from the absorption lines in the QSO spectrum with the oxygen abundance inferred from the strongline methods (R23 and N2). The two emission-line methods yield consistent results: [O/H] = 0:30 0:13. Based on the absorption lines in the QSO spectrum a metallicity of 0:49 0:05 is inferred at an impact parameter of 6.3 kpc from the centre of the galaxy with a column density of hydrogen of log(NHI=cm 2 ) = 20:65 0:05. The star formation rates of the galaxy from the UV continuum and H line can be reconciled assuming an amount of reddening of E(B V ) = 0:06 0:01, giving an inferred SFR of 13 1 M yr 1 (Chabrier IMF). From the HST imaging, the galaxy associated with the absorption is found to be a compact (re=1.12 kpc) object with a disc-like, elongated (axis ratio 0.17) structure indicating that the galaxy is seen close to edge-on. Moreover, the absorbing gas is located almost perpendicularly above the disc of the galaxy suggesting that the gas causing the absorption is not co-rotating with the disc. We investigate the stellar and dynamical masses from SED-fitting and emissionline widths, respectively, and find consistent results of 2 10 9 M . We suggest that the galaxy is a young proto-disc with evidence for a galactic outflow of enriched gas. This galaxy hints at how star-forming galaxies may be linked to the elusive population of damped Ly absorbers.
Galactic winds and extended Lyα emission from the host galaxies of high column density quasi-stellar object absorption systems

We present three-dimensional (3D) resonant radiative transfer simulations of the spatial and spectral diffusion of the Lyα radiation from a central source in the host galaxies of high column density absorption systems at z∼ 3. The radiative transfer simulations are based on a suite of cosmological galaxy formation simulations which reproduce a wide range of observed properties of damped Lyα absorption systems. The Lyα emission is predicted to be spatially extended up to several arcsec, and the spectral width of the Lyα emission is broadened to several hundred (in some case more than thousand) km s−1. The distribution and the dynamical state of the gas in the simulated galaxies are complex, the latter with significant contributions from rotation and both in- and out-flows. The emerging Lyα radiation extends to gas with column densities of NH I∼ 1018 cm−2 and its spectral shape varies strongly with viewing angle. The strong dependence on the central H i column density and the H i velocity field suggests that the Lyα emission will also vary strongly with time on time-scales of a few dynamical times of the central region. Such variations with time should be especially pronounced at times where the host galaxy undergoes a major merger and/or starburst. Depending on the pre-dominance of in- or out-flow along a given sightline and the central column density, the spectra show prominent blue peaks, red peaks or double-peaked profiles. Both spatial distribution and spectral shape are very sensitive to details of the galactic wind implementation. Stronger galactic winds result in more spatially extended Lyα emission and – somewhat counterintuitively – a narrower spectral distribution.
ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. II. MAGNETOHYDRODYNAMIC SIMULATIONS

We perform global unstratified three-dimensional magnetohydrodynamic simulations of an astrophysical boundary layer (BL)—an interface region between an accretion disk and a weakly magnetized accreting object such as a white dwarf—with the goal of understanding the effects of magnetic field on the BL. We use cylindrical coordinates with an isothermal equation of state and investigate a number of initial field geometries including toroidal, vertical, and vertical with zero net flux. Our initial setup consists of a Keplerian disk attached to a non-rotating star. In a previous work, we found that in hydrodynamical simulations, sound waves excited by shear in the BL were able to efficiently transport angular momentum and drive mass accretion onto the star. Here we confirm that in MHD simulations, waves serve as an efficient means of angular momentum transport in the vicinity of the BL, despite the magnetorotational instability (MRI) operating in the disk. In particular, the angular momentum current due to waves is at times larger than the angular momentum current due to MRI. Our results suggest that angular momentum transport in the BL and its vicinity is a global phenomenon occurring through dissipation of waves and shocks. This point of view is quite different from the standard picture of transport by a local anomalous turbulent viscosity. In addition to angular momentum transport, we also study magnetic field amplification within the BL. We find that the field is indeed amplified in the BL, but only by a factor of a few, and remains subthermal.
Wave-like avalanche propagation in the continuum field model of self-organized criticality

Travelling wave is identified as the mechanism of avalanche propagation in the continuum SOC (self-organized critical) system. Recovering the hidden causality based on a generalization of Fick's law, we lead the equivalent continuum equation which has spatiotemporal nonlocality. Taking into account of the hyperbolicity from the retarded response of the nonlocal kernel, it is possible to capture the propagating avalanche in constant speed. Verifying the computation, we analyze the evolution of instability as a nonlinear wave under the control of the threshold dynamics, which imposes the "metastability" as the survival condition of avalanche. Being consistent with the basic assumptions of SOC theory, the result shows unified features of the existing models. This provides a concept toward the SOC framework based on the physical principles of transport process.
Extending Landauer's Bound from Bit Erasure to Arbitrary Computation

Recent analyses have calculated the minimal thermodynamic work required to perform a computation pi when two conditions hold: the output of pi is independent of its input (e.g., as in bit erasure); we use a physical computer C to implement pi that is specially tailored to the environment of C, i.e., to the precise distribution over C's inputs, P_0. First I extend these analyses to calculate the work required even if the output of pi depends on its input, and even if C is not used with the distribution P_0 it was tailored for. Next I show that if C will be re-used, then the minimal work to run it depends only on the logical computation pi, independent of the physical details of C. This establishes a formal identity between the thermodynamics of (re-usable) computers and theoretical computer science. I use this identity to prove that the minimal work required to compute a bit string sigma on a "general purpose computer" rather than a special purpose one, i.e., on a universal Turing machine U, is k_BT ln(2) times the sum of three terms: The Kolmogorov complexity of sigma, log of the Bernoulli measure of the set of strings that compute sigma, and log of the halting probability of U. I also prove that using C with a distribution over environments results in an unavoidable increase in the work required to run the computer, even if it is tailored to the distribution over environments. I end by using these results to relate the free energy flux incident on an organism / robot / biosphere to the maximal amount of computation that the organism / robot / biosphere can do per unit time.
Rare Words: A Major Problem for Contextualized Embeddings And How to Fix it by Attentive Mimicking

Pretraining deep neural network architectures with a language modeling objective has brought large improvements for many natural language processing tasks. Exemplified by BERT, a recently proposed such architecture, we demonstrate that despite being trained on huge amounts of data, deep language models still struggle to understand rare words. To fix this problem, we adapt Attentive Mimicking, a method that was designed to explicitly learn embeddings for rare words, to deep language models. In order to make this possible, we introduce one-token approximation, a procedure that enables us to use Attentive Mimicking even when the underlying language model uses subword-based tokenization, i.e., it does not assign embeddings to all words. To evaluate our method, we create a novel dataset that tests the ability of language models to capture semantic properties of words without any task-specific fine-tuning. Using this dataset, we show that adding our adapted version of Attentive Mimicking to BERT does substantially improve its understanding of rare words.
THE OPTICAL COMPANION TO THE BINARY MILLISECOND PULSAR J1824−2452H IN THE GLOBULAR CLUSTER M28

We report on the optical identification of the companion star to the eclipsing millisecond pulsar (MSP) PSR J1824−2452H in the galactic globular cluster M28 (NGC 6626). This star is at only 0. ″2 from the nominal position of the pulsar and it shows optical variability (∼0.25 mag) that nicely correlates with the pulsar orbital period. It is located on the blue side of the cluster main sequence, ∼1.5 mag fainter than the turnoff point. The observed light curve shows two distinct and asymmetric minima, suggesting that the companion star is suffering tidal distortion from the pulsar. This discovery increases the number of non-degenerate MSP companions optically identified so far in globular clusters (four out of seven), suggesting that these systems could be a common outcome of the pulsar recycling process, at least in dense environments where they can be originated by exchange interactions.
RESULTS ON NEUTRINOLESS DOUBLE-BETA DECAY FROM GERDA PHASE I

The GERmanium Detector Array, GERDA, is designed to search for neutrinoless double-beta (0νββ) decay of 76Ge and it is installed in the Laboratori Nazionali del Gran Sasso (LNGS) of INFN, Italy. In this review, the detection principle and detector setup of GERDA are described. Also, the main physics results by GERDA Phase I, are discussed. They include the measurement of the half-life of 2νββ decay, the background decomposition of the energy spectrum and the techniques for the discrimination of the background, based on the pulse shape of the signal. In the last part of this review, the estimation of a limit on the half-life of 0νββ ( at 90% C.L.) and the comparison with previous results are discussed. GERDA data from Phase I strongly disfavor the recent claim of 0νββ discovery, based on data from the Heidelberg–Moscow experiment.
X-RAY EMISSION FROM TRANSIENT JET MODEL IN BLACK HOLE BINARIES

While the non-thermal radio through at least near-infrared emission in the hard state in X-ray binaries (XRBs) is known to originate in jets, the source of the non-thermal X-ray component is still uncertain. We introduce a new model for this emission, which takes into account the transient nature of outflows, and show that it can explain the observed properties of the X-ray spectrum. Rapid radiative cooling of the electrons naturally accounts for the break often seen below around 10 keV, and for the canonical spectral slope Fν∝ν−1/2 observed below the break. We derive the constraints set by the data for both synchrotron- and Compton-dominated models. We show that for the synchrotron-dominated case, the jet should be launched at radii comparable to the inner radius of the disk (∼few 100 rs for the 2000 outburst of XTE J1118+480), with typical magnetic field B ≳ 106 G. We discuss the consequences of our results for the possible connection between the inflow and outflow in the hard state of XRBs.
EVIDENCE FOR NON-EVOLVING Fe ii/Mg ii RATIOS IN RAPIDLY ACCRETING z ∼ 6 QSOs

Quasars (QSOs) at the highest known redshift (z ∼ 6) are unique probes of the early growth of supermassive black holes (BHs). Until now, only the most luminous QSOs have been studied, often one object at a time. Here we present the most extensive consistent analysis to date of 4 < z < 6.5 QSOs with observed near-infrared spectra, combining three new z ∼ 6 objects from our ongoing Very Large Telescope–Infrared Spectrometer And Array Camera program with nineteen sources from the literature. The new sources extend the existing Sloan Digital Sky Survey (SDSS) sample toward the faint end of the QSO luminosity function. Using a maximum likelihood fitting routine optimized for our spectral decomposition, we estimate the BH mass (MBH), the Eddington ratio (defined as Lbol/LEdd), and the Fe ii/Mg ii line ratio, a proxy for the chemical abundance, to characterize both the central object and the broad-line region gas. The QSOs in our sample host BHs with masses of ∼109 M☉ that are accreting close to the Eddington luminosity, consistent with earlier results. We find that the distribution of observed Eddington ratios is significantly different than that of a luminosity-matched comparison sample of SDSS QSOs at lower redshift (0.35 < z < 2.25): the average 〈log (Lbol/LEdd)〉 = −0.37 (Lbol/LEdd ∼ 0.43) with a scatter of 0.20 dex for the z > 4 sample and the 〈log (Lbol/LEdd)〉 = −0.80 (Lbol/LEdd ∼ 0.16) with a scatter of 0.24 dex for the 0.35 < z < 2.25 sample. This implies that, at a given luminosity, the MBH at high-z is typically lower than the average MBH of the lower-redshift population, i.e., the z > 4 sources are accreting significantly faster than the lower-redshift ones. We show that the derived Fe ii/Mg ii ratios depend sensitively on the analysis performed: our self-consistent, homogeneous analysis significantly reduces the Fe ii/Mg ii scatter found in previous studies. The measured Fe ii/Mg ii line ratios show no sign of evolution with cosmic time in the redshift range 4 < z < 6.5. If the Fe ii/Mg ii line ratio is used as a secondary proxy of the Fe/Mg abundance ratio, this implies that the QSOs in our sample have undergone a major episode of Fe enrichment in the few 100 Myr preceding the cosmic age at which they are observed.
Leveraging knowledge management systems for business modelling in technology start-ups: an exploratory study

ABSTRACT Business model (BM) creation and development for Technological Start-ups (TSs) strongly grounds on knowledge assets. Despite such relevance, it emerges the paucity of research on BM within the knowledge-based research streams, and specifically for TSs that need a proper digital-enabled knowledge management system (KMS) to ensure the effective organisation of their knowledge assets. To investigate such issues, a study on the relationships between BM and knowledge assets grouped by the Intellectual Capital (IC) elements has been carried out by submitting a semi-structured questionnaire to a sample of 52 Italian TSs. Results show that both the foundation and innovation of BM rely mainly on human capital, followed by relational and structural capital. The study identifies also the trajectories that TSs follow to define their BM by leveraging their IC, and the enabling conditions. The paper ends with a discussion about how digital-enabled KMS can support the exploitation of IC for TSs.
A Microlocal Characterization of Lipschitz Continuity

We study continuous maps between differential manifolds from a microlocal point of view. In particular, we characterize the Lipschitz continuity of these maps in terms of the microsupport of the constant sheaf on their graph. Furthermore, we give lower and upper bounds on the microsupport of the graph of a continuous map and use these bounds to characterize strict differentiability in microlocal terms.