Miracle-dz/UniFAR-FTUs huggingface dataset:
Stellar classification of CoRoT targets

The CoRoT faint stars channel observed about 163 600 targets to detect transiting planetary companions. Because CoRoT targets are faint (11< r <16) and close to the galactic plane, only a small subsample has been observed spectroscopically. We describe the latest classification scheme used to derive the spectral type of CoRoT targets, which is based on broadband multi-colour photometry. We assess the accuracy of this spectral classification for the first time. We find that the classification method performs better for stars that were observed during the mission-dedicated photometric ground-based campaigns.The luminosity class is wrong for less than 7% of the targets. Generally, the effective temperature of stars classified as early type (O, B, and A) is overestimated. Conversely, the temperature of stars classified as later type tends to be underestimated. This is mainly due to the adverse effect of interstellar reddening. We find that the median error on the effective temperature is less than 5% for dwarf stars classified with a spectral later than F0, but it is worse for earlier type stars, with up to 20\% error for A and late-B dwarfs, and up to 70% for early-B and O-type dwarfs. Similar results are found for giants, with a median error that is lower than 7% for G- and later type giants, but greater than 25% for earlier types. Overall, we find an average median absolute temperature difference |Delta Teff| = 533+\-6 K for the whole sample of stars classified as dwarfs and |Delta Teff| = 280+\-3 K for the whole sample of giant stars. The corresponding standard deviation is of about 92+\-5 K for dwarfs and 304+\-4 K for giants. Typically for late-type stars, this means that the classification is accurate to about half a class.
ON GENERALIZED-FUNCTION SOLUTIONS OF A FIRST ORDER LINEAR SINGULAR DIFFERENTIAL EQUATION IN THE SPACE K’ VIA FOURIER TRANSFORM

The main purpose of this work is to obtain and describe the solutions of the non-homogeneous first order linear singular differential equation of the following type: with two real numbers, and in the space of generalized functions We look for the solution of this equation in the form of with the unknown coefficients to be determined. We also obtain and analyze the classical solutions of the homogeneous equation.
Small-x Asymptotics of the Quark Helicity Distribution : Analytic Results

In this Letter, we analytically solve the evolution equations for the small-x asymptotic behavior of the (flavor singlet) quark helicity distribution in the large-Nc limit. These evolution equations form a set of coupled integro-differential equations, which previously could only be solved numerically. This approximate numerical solution, however, revealed simplifying properties of the small-x asymptotics, which we exploit here to obtain an analytic solution. We find that the small-x power-law tail of the quark helicity distribution scales as ∆q(x,Q) ∼ ( 1 x )αh with αh = 4 √3√αsNc 2π , in excellent agreement with the numerical estimate αh ≈ 2.31 √ αsNc 2π obtained previously. We then verify this solution by cross-checking the predicted scaling behavior of the auxiliary “neighbor dipole amplitude” against the numerics, again finding excellent agreement.
Constraining dark matter late-time energy injection: decays and p-wave annihilations

We use the latest cosmic microwave background (CMB) observations to provide updated constraints on the dark matter lifetime as well as on p-wave suppressed annihilation cross sections in the 1 MeV to 1 TeV mass range. In contrast to scenarios with an s-wave dominated annihilation cross section, which mainly affect the CMB close to the last scattering surface, signatures associated with these scenarios essentially appear at low redshifts (z≲50) when structure began to form, and thus manifest at lower multipoles in the CMB power spectrum. We use data from Planck, WMAP9, SPT and ACT, as well as Lyman–α measurements of the matter temperature at z ∼ 4 to set a 95% confidence level lower bound on the dark matter lifetime of ∼ 4 × 1025 s for mχ = 100 MeV. This bound becomes lower by an order of magnitude at mχ = 1 TeV due to inefficient energy deposition into the intergalactic medium. We also show that structure formation can enhance the effect of p-wave suppressed annihilation cross sections by many orders of magnitude with respect to the background cosmological rate, although even with this enhancement, CMB constraints are not yet strong enough to reach the thermal relic value of the cross section.
A semi-analytic model comparison: testing cooling models against hydrodynamical simulations

We compare predictions of cooled masses and cooling rates from three stripped-down Semi-Analytic Models (SAMs) of galaxy formation with the results of N-body+SPH simulations with gas particle mass of 3.9x10^6 Msun, where radiative cooling of a gas of primordial composition is implemented. We also run a simulation where cooling is switched on at redshift ~2, in order to test cooling models in a regime in which their approximations are expected to be valid. We confirm that cooling models implemented in SAMs are able to predict the amount of cooled mass at z=0 to within ~20 per cent. However, some relevant discrepancies are found. (i) When the contribution from poorly resolved halos is subtracted out, SAMs tend to under-predict by ~30 per cent the mass that cools in the infall-dominated regime. (ii) At large halo masses SAMs tend to over-predict cooling rates, though the numerical result may be affected by the use of SPH. (iii) As found in our previous work, cooling rates are found to be significantly affected by model details: simulations disfavour models with large cores and with quenching of cooling at major mergers. (iv) When cooling is switched on at z~2, cold gas accumulates very quickly in the simulated halos. This accumulation is reproduced by SAMs with varying degrees of accuracy.
Correction to: A simple method to estimate radial velocity variations due to stellar activity using photometry

We present a new, simple method to predict activity-induced radial velocity (RV) variations using high-precision time series photometry. It is based on insights from a simple spot model, has only two free parameters (one of which can be estimated from the light curve) and does not require knowledge of the stellar rotation period. We test the method on simulated data and illustrate its performance by applying it to MOST/SOPHIE observations of the planet host star HD 189733, where it gives almost identical results to much more sophisticated but highly degenerate models, and synthetic data for the Sun, where we demonstrate that it can reproduce variations well below the m s−1 level. We also apply it to quarter 1 data for Kepler transit candidate host stars, where it can be used to estimate RV variations down to the 2–3 m s−1 level, and show that RV amplitudes above that level may be expected for approximately two-thirds of the candidates we examined.
Absorption signatures of warm-hot gas at low redshift: Ne viii

At z {lt} 1 a large fraction of the baryons is thought to reside in diffuse gas that has been shock-heated to high temperatures (10$^{5}$-10$^{6}$ K). Absorption by the 770.41, 780.32 a doublet of Ne VIII in quasar spectra represents a unique tool to study this elusive warm-hot phase. We have developed an analytic model for the properties of Ne VIII absorbers that allows for an inhomogeneous metal distribution. Our model agrees with the predictions of a simulation from the OverWhelmingly Large Simulations project indicating that the average line-of-sight metal-filling fraction within the absorbing gas is low (c$_L$ { ilde} 0.1). Most of the Ne VIII in our model is produced in low-density, collisionally ionized gas (n$_H$ = 10$^{-6}$-10$^{-4}$ cm$^{-3}$, T = 10$^{5}$-10$^{6}$ K). Strong Ne VIII absorbers (log$_{10}$(N$_{NeVIII}$/cm$^{-2}$){gsim}14), like those recently detected by Hubble Space Telescope/Cosmic Origins Spectrograph, are found to arise in higher density gas (n$_H$ {gsim} 10$^{-4}$ cm$^{-3}$, T {ap} 5 { imes} 10$^{5}$ K). Ne VIII cloudlets harbour only 1 per cent of the cosmic baryon budget. The baryon content of the surrounding gas (which has similar densities and temperatures as the Ne VIII cloudlets) is a factor c_L^{}${$-1$}$ higher. We conclude that Ne VIII absorbers are robust probes of shock-heated diffuse gas, but that spectra with signal-to-noise ratios S/N {gt} 100 would be required to detect the bulk of the baryons in warm-hot gas.
Einstein-like geometric structures on surfaces

An AH (affine hypersurface) structure is a pair comprising a projective equivalence class of torsion-free connections and a conformal structure satisfying a compatibility condition which is automatic in two dimensions. They generalize Weyl structures, and a pair of AH structures is induced on a co-oriented non-degenerate immersed hypersurface in flat affine space. The author has defined for AH structures Einstein equations, which specialize on the one hand to the usual Einstein Weyl equations and, on the other hand, to the equations for affine hyperspheres. Here these equations are solved for Riemannian signature AH structures on compact orientable surfaces, the deformation spaces of solutions are described, and some aspects of the geometry of these structures are related. Every such structure is either Einstein Weyl (in the sense defined for surfaces by Calderbank) or is determined by a pair comprising a conformal structure and a cubic holomorphic differential, and so by a convex flat real projective structure. In the latter case it can be identified with a solution of the Abelian vortex equations on an appropriate power of the canonical bundle. On the cone over a surface of genus at least two carrying an Einstein AH structure there are Monge-Amp\`ere metrics of Lorentzian and Riemannian signature and a Riemannian Einstein K\"ahler affine metric. A mean curvature zero spacelike immersed Lagrangian submanifold of a para-K\"ahler four-manifold with constant para-holomorphic sectional curvature inherits an Einstein AH structure, and this is used to deduce some restrictions on such immersions.
The orbital periods of subdwarf B binaries produced by the first stable Roche Lobe overflow channel

Long-orbital-period subdwarf B (sdB) stars with main-sequence companions are believed to be the product of stable Roche Lobe overflow (RLOF), a scenario challenged by recent observations. Here, we represent the results of a systematic study of the orbital-period distribution of sdB binaries in this channel using detailed binary evolution calculations. We show that the observed orbital-period distribution of long-period sdB binaries can be well explained by this scenario. Furthermore, we find that, if the progenitors of the sdB stars have initial masses below the helium flash mass, the sdB binaries produced from stable RLOF follow a unique mass-orbital period relation for a given metallicity Z; increasing the orbital period from similar to 400 to similar to 1100 d corresponds to increasing the mass of the sdB star from similar to 0.40 to similar to 0.49 M-circle dot for Z = 0.02. We suggest that the longest sdB binaries (with orbital period > 1100 d) could be the result of atmospheric RLOF. The mass-orbital period relation can be tested observationally if the mass of the sdB star can be determined precisely, e.g. from asteroseismology. Using this relation, we revise the orbital period distribution of sdB binaries produced by the first stable RLOF channel for the best-fitting model of Han et al (2003), and show that the orbital period has a peak around 830 d.
STAR FORMATION MODELS FOR THE DWARF GALAXIES NGC 2915 AND NGC 1705

Crucial to a quantitative understanding of galaxy evolution are the properties of the interstellar medium that regulate galactic-scale star formation activity. We present here the results of a suite of star formation models applied to the nearby blue compact dwarf galaxies NGC 2915 and NGC 1705. Each of these galaxies has a stellar disk embedded in a much larger, essentially starless H i disk. These atypical stellar morphologies allow for rigorous tests of star formation models that examine the effects on star formation of the H i, stellar, and dark matter mass components, as well as the kinematics of the gaseous and stellar disks. We use far-ultraviolet and 24 μm images from the Galaxy Evolution Explorer and the Spitzer Infrared Nearby Galaxies Survey, respectively, to map the spatial distribution of the total star formation rate surface density within each galaxy. New high-resolution H i line observations obtained with the Australia Telescope Compact Array are used to study the distribution and dynamics of each galaxy's neutral interstellar medium. The standard Toomre Q parameter is unable to distinguish between active and non-active star-forming regions, predicting the H i disks of the dwarfs to be sub-critical. Two-fluid instability models incorporating the stellar and dark matter components of each galaxy, in addition to the gaseous component, yield unstable portions of the inner disk. Finally, a formalization in which the H i kinematics are characterized by the rotational shear of the gas produces models that very accurately match the observations. This suggests the time available for perturbations to collapse in the presence of rotational shear to be an important factor governing galactic-scale star formation.
THE NATURE OF γ-RAY LOUD NARROW-LINE SEYFERT I GALAXIES PKS 1502+036 AND PKS 2004−447

Variable γ-ray emission has been discovered in five radio-loud narrow-line Seyfert 1 (NLSy1) galaxies by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. This has clearly demonstrated that these NLSy1 galaxies do have relativistic jets similar to two other cases of γ-ray-emitting active galactic nuclei (AGNs), namely, blazars and radio galaxies. We present here our results on the multi-band analysis of two γ-ray-emitting NLSy1 galaxies, namely, PKS 1502+036 (z = 0.409) and PKS 2004−447 (z = 0.240), using archival data. We generate multi-band long-term light curves of these sources, build their spectral energy distribution (SED), and model them using a one-zone leptonic model. They resemble more the SEDs of the flat spectrum radio quasar (FSRQ) class of AGNs. We then compare the SEDs of these two sources with two other Fermi-detected AGNs along the traditional blazar sequence, namely, the BL Lac Mrk 421 (z = 0.03) and the FSRQ 3C 454.3 (z = 0.86). The SEDs of both PKS 1502+036 and PKS 2004−447 are found to be intermediate to the SEDs of Mrk 421 and 3C 454.3. In the γ-ray spectral index versus γ-ray luminosity plane, both these NLSy1 galaxies occupy a distinct position, wherein they have luminosity between Mrk 421 and 3C 454.3; however, their steep γ-ray spectra are similar to 3C 454.3. Their Compton dominance as well as their X-ray spectral slope also lie between Mrk 421 and 3C 454.3. We argue that the physical properties of both PKS 1502+036 and PKS 2004−447 are generally similar to blazars and intermediate between FSRQs and BL Lac objects and these sources thus could fit into the traditional blazar sequence.
Metals and dust content across the galaxies M 101 and NGC 628

This work was partially supported by the Spanish Ministerio de Economia y Competitividad under grants AYA2016-79724-C4-4-P and AYA2016-79724-C4-3-P, and excellence project PEX2011-FQM-7058 of Junta de Andalucia (Spain). MR acknowledges support by the research projects AYA2014-53506-P and AYA2017-84897-P from the Spanish Ministerio de Economia y Competitividad and Junta de Andalucia grant FQM108; support from the European Regional Development Funds (FEDER) is acknowledged.
Thickness and growth-condition dependence of in-situ mobility and carrier density of epitaxial thin-film Bi2Se3

Bismuth selenide Bi2Se3 was grown by molecular beam epitaxy, while carrier density and mobility were measured directly in situ as a function of film thickness. Carrier density shows high interface n-doping (1.5 × 1013 cm−2) at the onset of film conduction and bulk dopant density of ∼5 × 1011 cm−2 per quintuple-layer unit, roughly independent of growth temperature profile. Mobility depends more strongly on the growth temperature and is related to the crystalline quality of the samples quantified by ex-situ atomic force microscopy measurements. These results indicate that Bi2Se3 as prepared by widely employed parameters is n-doped before exposure to atmosphere, the doping is largely interfacial in origin, and dopants are not the limiting disorder in present Bi2Se3 films.
HECTOMAP AND HORIZON RUN 4: DENSE STRUCTURES AND VOIDS IN THE REAL AND SIMULATED UNIVERSE

HectoMAP is a dense redshift survey of red galaxies covering a 53 deg2 strip of the northern sky. HectoMAP is 97% complete for galaxies with r < 20.5, (g− r) > 1.0, and (r − i) > 0.5. The survey enables tests of the physical properties of large-scale structure at intermediate redshift against cosmological models. We use the Horizon Run 4, one of the densest and largest cosmological simulations based on the standard Λ Cold Dark Matter (ΛCDM) model, to compare the physical properties of observed large-scale structures with simulated ones in a volume-limited sample covering 8 × 106 h−3 Mpc3 in the redshift range 0.22 < z < 0.44. We apply the same criteria to the observations and simulations to identify over- and under-dense large-scale features of the galaxy distribution. The richness and size distributions of observed over-dense structures agree well with the simulated ones. Observations and simulations also agree for the volume and size distributions of under-dense structures, voids. The properties of the largest over-dense structure and the largest void in HectoMAP are well within the distributions for the largest structures drawn from 300 Horizon Run 4 mock surveys. Overall the size, richness and volume distributions of observed large-scale structures in the redshift range 0.22 < z < 0.44 are remarkably consistent with predictions of the standard ΛCDM model.
Dynamical system analysis of hybrid metric-Palatini cosmologies

The so-called $f(X)$ hybrid metric-Palatini gravity, where $X=R+T$, with $T$ the stress-energy trace and $R$ the Ricci scalar, presents a unique viable generalization of the $f(R)$ theories within the metric-affine formalism. In this paper, the cosmology of the $f(X)$ theories is studied using the dynamical system approach. The method consists of formulating the propagation equation in terms of suitable (expansion-normalized) variables as an autonomous system. The fixed points of the system then represent exact cosmological solutions described by power law or de Sitter expansion. The formalism is applied to two classes of $f(X)$ models, revealing both standard cosmological fixed points and new accelerating solutions that can be attractors in the phase space. In addition, the fixed point with vanishing expansion rate is considered with special care in order to characterize the stability of Einstein static spaces and bouncing solutions.
A census of Hα emitters in the intergalactic medium of the NGC 2865 system

Tidal debris, which are rich in HI gas and formed in interacting and merging systems, are suitable laboratories to study star formation outside galaxies. Recently, several such systems were observed, which contained many young star forming regions outside the galaxies. In previous works, we have studied young star forming regions outside galaxies in different systems with optical and/or gaseous tidal debris, in order to understand how often they occur and in which type of environments. In this paper, we searched for star forming regions around the galaxy NGC 2865, a shell galaxy that is circled by a ring of HI with a total mass of 1.2×10 9 M� . U sing the multi-slit imaging spectroscopy technique with the Gemini telescope, we detected all Hα emitting sources in the surroundings of the galaxy NGC 2865, down to a flux limit of 10 −18 erg cm −2 s −1 A −1 . With the spectra information and the near and far-ultraviolet flux, we characterize the star formation rates, masses, ages, and metallicities for these HII regions. In total, we found 26 emission-line sources in a 60 × 60 Kpc field centered over the southeastern tail of the HI gas present around the galaxy NGC 2865. Out of the 26 Hα emitters, 19 are in the satellite galaxy FGCE 0745, and seven are intergalactic HII regions scattered over the south tail of the HI gas around NGC 2865. We found that the intergalactic HII regions are young (<200 Myr) with stellar masses in the range 4 × 10 3 M� to 17 × 10 6 M� . These are found in a region of low HI gas density, where the probability of forming stars is expected to be low. For one of the intergalactic HII regions, we estimated a solar oxygen abundance of 12 + log(O/H) ∼ 8.7. We also were able to estimate the metallicity for the satellite galaxy FGCE 0745 to be 12 + log(O/H) ∼ 8.0. Given these physical parameters, the intergalactic HII regions are consistent with young star forming regions (or clusters), which are born in situ outside the NGC 2865 galaxy from a pre-enriched gas removed from the host galaxies in a merger event. The relevance of these observations is discussed.
Constraints on star formation driven galaxy winds from the mass–metallicity relation at z= 0

We extend a chemical evolution model relating galaxy stellar mass and gas-phase oxygen abundance (the mass–metallicity relation) to explicitly consider the mass-dependence of galaxy gas fractions and outflows. Using empirically derived scalings of galaxy mass with halo virial velocity in conjunction with the most recent observations of z∼ 0 total galaxy cold gas fractions and the mass–metallicity relation, we place stringent global constraints on the magnitude and scaling of the efficiency with which star-forming galaxies expel metals. We demonstrate that under the assumptions that metal accretion is negligible and the stellar initial mass function does not vary, efficient outflows are required to reproduce the mass–metallicity relation; without winds, gas-to-stellar mass ratios ≳0.3 dex higher than observed are needed. Moreover, z= 0 gas fractions are low enough that while they have some effect on the magnitude of outflows required, the slope of the gas fraction–stellar mass relation does not strongly affect our conclusions on how the wind efficiencies must scale with galaxy mass. Because theoretical descriptions of the mass loading factor , where is the mass outflow rate and is the star formation rate, are often cast in terms of the depth of the galaxy potential well, which is in turn linked to the host halo virial velocity vvir, we use one of the latest abundance matching analyses to describe outflow efficiencies in terms of vvir rather than stellar mass. Despite systematic uncertainties in the normalization and slope of the mass–metallicity relation, we show that the metal expulsion efficiency ζw≡ (Zw/Zg)ηw (where Zw is the wind metallicitiy and Zg is the interstellar medium metallicity) must be both high and scale steeply with mass. Specifically, we show that ζw≫ 1 and ζw∝v−3vir or steeper. In contrast, momentum- or energy-driven outflow models suggest that ηw should scale as v−1vir or v−2vir, respectively, implying that the Zw–M★ relation should be shallower than the Zg–M★ relation.