Search

In previous work, we showed that a semi-empirical model in which galaxies in host dark matter haloes are assigned stellar masses via a stellar mass–halo mass (SMHM) relation and sizes (R e) via a linear and tight R e– R h relation can faithfully reproduce the size function of local Sloan Digital Sky Survey (SDSS) central galaxies and the strong size evolution of massive galaxies (MGs; M star > 1011.2 M⊙). In this third paper of the series, we focus on the population of satellite MGs. We find that without any additional calibration and irrespective of the exact SMHM relation, fraction of quenched galaxies, or level of stellar stripping, the same model is able to reproduce the local size function of quiescent satellite MGs in SDSS. In addition, the same model can reproduce the puzzling weak dependence of mean size on host halo mass for both central and satellite galaxies. The model also matches the size function of star-forming satellite MGs, after assuming that some of them transform into massive lenticulars in a few Gyr after infalling in the group/cluster environment. However, the vast majority of satellite lenticulars are predicted to form before infall. The R e– R h relation appears to be fundamental to connect galaxies and their host haloes. [ABSTRACT FROM AUTHOR]

Several observational studies have shown that many Galactic globular clusters (GCs) are characterized by internal rotation. Theoretical studies of the dynamical evolution of rotating clusters have predicted that, during their long-term evolution, these stellar systems should develop a dependence of the rotational velocity around the cluster's centre on the mass of stars, with the internal rotation increasing for more massive stars. In this paper, we present the first observational evidence of the predicted rotation–mass trend. In our investigation, we exploited the Gaia Data Release 3 catalogue of three GCs: NGC 104 (47 Tuc), NGC 5139 (ω Cen), and NGC 5904 (M 5). We found clear evidence of a cluster rotation–mass relation in 47 Tuc and M 5, while in ω Cen, the dynamically youngest system among the three clusters studied here, no such trend was detected. [ABSTRACT FROM AUTHOR]

This paper reports our discovery of the most massive supercluster, termed the King Ghidorah Supercluster (KGSc), at z = 0.50–0.64 in the Third Public Data Release of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP PDR3) over 690 deg2, as well as an initial result for a galaxy and dark matter mapping. The primary structure of the KGSc comprises triple broad weak-lensing (WL) peaks over 70 comoving Mpc. Such extensive WL detection at z > 0.5 can only currently be achieved using the wide-field high-quality images produced by the HSC-SSP. The structure is also contiguous with multiple large-scale structures across a ∼400 comoving Mpc scale. The entire field has a notable overdensity (δ = 14.7 ± 4.5) of red-sequence clusters. Additionally, large-scale underdensities can be found in the foreground along the line of sight. We confirmed the overdensities in stellar mass and dark matter distributions to be tightly coupled and estimated the total mass of the main structure to be 1 × 1016 solar masses, according to the mock data analyses based on large-volume cosmological simulations. Further, upcoming wide-field multi-object spectrographs such as the Subaru Prime Focus Spectrograph may aid in providing additional insights into distant superclusters beyond the 100 Mpc scale. [ABSTRACT FROM AUTHOR]

We apply our recently suggested statistical approach to thermal evolution of isolated neutron stars and accreting quasi-stationary neutron stars in X-ray transients for constraining the position and relative broadening α of the direct Urca threshold of powerful neutrino emission in neutron star cores. We show that most likely explanation of observations corresponds to α ≈ 0.08-0.10 and to the neutron star mass, at which the direct Urca process is open, MD ≈ 1.6-1.8 M⊙. [ABSTRACT FROM AUTHOR]

Feedback from an active galactic nucleus (AGN) is often implicated as a mechanism that leads to the quenching of galactic star formation. However, AGN-driven quenching is challenging to reconcile with observations that AGN hosts tend to harbour equal (or even excess) amounts of gas compared with inactive galaxies of similar stellar mass. In this paper, we investigate whether AGN feedback happens on sub-galactic (kpc) scales, an effect that might be difficult to detect with global gas measurements. Using kpc-scale measurements of molecular gas (⁠|$\Sigma _{\rm H_2}$|⁠) and stellar mass (Σ⋆) surface densities, taken from the Extragalactic Data base for Galaxy Evolution–Calar Alto Legacy Integral Field Area survey, we show that the gas fractions of central AGN regions are typically a factor of ∼ 2 lower than those in star-forming regions. Based on four galaxies with the best spaxel statistics, the difference between AGN and star-forming gas fractions is seen even within a given galaxy, indicating that AGN feedback is able to deplete the molecular gas reservoir in the central few kpc. [ABSTRACT FROM AUTHOR]

In this paper, we present an attempt to estimate the redshift evolution of the molecular to neutral gas mass ratio within galaxies (at fixed stellar mass). For a sample of five nearby grand design spirals located on the main-sequence (MS) of star-forming galaxies, we exploit maps at 500 pc resolution of stellar mass and star formation rate (M ⋆ and SFR). For the same cells, we also have estimates of the neutral (M H  i ) and molecular (⁠|$M_{\rm H_2}$|⁠) gas masses. To compute the redshift evolution, we exploit two relations: (i) one between the molecular-to-neutral mass ratio and the total gas mass (M gas), whose scatter shows a strong dependence with the distance from the spatially resolved MS, and (ii) the one between |$\log (M_{\rm {H_2}}/M_{\star })$| and log (M H  i / M ⋆). For both methods, we and that |$M_{\rm H_2}$| / M H  i within the optical radius slightly decreases with redshift, contrary to common expectations of galaxies becoming progressively more dominated by molecular hydrogen at high redshifts. We discuss possible implications of this trend on our understanding of the internal working of high-redshift galaxies. [ABSTRACT FROM AUTHOR]

We present a systematic analysis of the reaction of dark matter distribution to galaxy formation across more than eight orders of magnitude in stellar mass. We extend the previous work presented in the NIHAO-IV paper by adding 46 new high-resolution simulations of massive galaxies performed with the inclusion of black hole feedback. We show that outflows generated by the active galactic nucleus (AGN) are able to partially counteract the dark matter contraction due to the large central stellar component in massive haloes. The net effect is to relax the central dark matter distribution that moves to a less cuspy density profiles at halo mass larger than ≈3 × 1012 M⊙. The scatter around the mean value of the density profile slope (α) is fairly constant (Δα ≈ 0.3), with the exception of galaxies with halo masses around 1012 M⊙, at the transition from stellar to AGN feedback dominated systems, where the scatter increases by almost a factor of 3. We provide useful fitting formulae for the slope of the dark matter density profiles at few per cent of the virial radius for the whole stellar mass range: 105–1012 M⊙ (2 × 109 to 5 × 1013 M⊙ in halo mass). [ABSTRACT FROM AUTHOR]

The blue large-amplitude pulsators (BLAPs) constitute a new class of pulsating stars. They are hot stars with effective temperatures of ∼30 000 K and surface gravities of log g ∼ 4.9, that pulsate with periods in the range 20−40 min. Until now, their origin and evolutionary state, as well as the nature of their pulsations, were not been unveiled. In this paper, we propose that the BLAPs are the hot counterpart of the already known pulsating pre-extremely low mass (pre-ELM) white dwarf (WD) stars, that are He-core low-mass stars resulting from interacting binary evolution. Using fully evolutionary sequences, we show that the BLAPs are well represented by pre-ELM WD models with high effective temperature and stellar masses ∼0.34 M⊙. From the analysis of their pulsational properties, we find that the observed variabilities can be explained by high-order non-radial g-mode pulsations or, in the case of the shortest periods, also by low-order radial modes, including the fundamental radial mode. The theoretical modes with periods in the observed range are unstable due to the κ mechanism associated with the Z-bump in the opacity at log T ∼ 5.25. [ABSTRACT FROM AUTHOR]

In this first of a series of papers, we utilize results for around 2000 star cluster models simulated using the MOCCA code for star cluster evolution (Survey Database I) to determine the astrophysical properties and local merger rate densities for coalescing binary black holes (BBHs) originating from globular clusters (GCs). We extracted information for all coalescing BBHs that escape the cluster models and subsequently merge within a Hubble time along with BBHs that are retained in our GC models and merge inside the cluster via gravitational wave emission. By obtaining results from a substantial number of realistic star cluster models that cover different initial parameters, we have an extremely large statistical sample of BBHs with stellar mass and massive stellar BH (... 100Mʘ) components that merge within a Hubble time. Using these data, we estimate local merger rate densities for these BBHs originating from GCs to be at least 5.4 Gpc-3 yr-1. [ABSTRACT FROM AUTHOR]

Using star-forming galaxies sample in the nearby Universe (0.02 < z < 0.10) selected from the Sloan Digital Sky Survey (DR7) and Galaxy Evolution Explorer all-sky survey (GR5), we present a new empirical calibration for predicting dust extinction of galaxies from the Hα-to-FUV flux ratio. We find that the Hα dust extinction (AHα) derived with Hα/Hß ratio (Balmer decrement) increases with increasing Hα/UV ratio as expected, but there remains a considerable scatter around the relation, which is largely dependent on stellar mass and/or Hα equivalent width (EWHα). At fixed Hα/UV ratio, galaxies with higher stellar mass (or galaxies with lower EWHα) tend to be more highly obscured by dust. We quantify this trend and establish an empirical calibration for predicting AHα with a combination of Hα/UV ratio, stellar mass, and EWHα, with which we can successfully reduce the systematic uncertainties accompanying the simple Hα/UV approach by ~15-30 per cent. The new recipes proposed in this study will provide a convenient tool for predicting dust extinction level of galaxies particularly when Balmer decrement is not available. By comparing AHα (derived with Balmer decrement) and AUV (derived with IR/UV luminosity ratio) for a subsample of galaxies for which AKARI far-infrared photometry is available, we demonstrate that more massive galaxies tend to have higher extra extinction towards the nebular regions compared to the stellar continuum light. Considering recent studies reporting smaller extra extinction towards nebular regions for highredshift galaxies, we argue that the dust geometry within high-redshift galaxies resembles low-mass galaxies in the nearby Universe. [ABSTRACT FROM AUTHOR]

In this paper, we discuss a method for the generation of mock tidal streams. Using an ensemble of simulations in an isochrone potential where the actions and frequencies are known, we derive an empirical recipe for the evolving satellite mass and the corresponding mass-loss rate, and the ejection conditions of the stream material. The resulting stream can then be quickly generated either with direct orbital integration, or by using the action-angle formalism. The model naturally produces streaky features within the stream. These are formed due to the radial oscillation of the progenitor and the bursts of stars emitted near pericentre, rather than clumping at particular oscillation phases as sometimes suggested. When detectable, these streaky features are a reliable diagnostic for the stream's direction of motion and encode other information on the progenitor and its orbit. We show several tests of the recipe in alternate potentials, including a case with a chaotic progenitor orbit which displays a marked effect on the width of the stream. Although the specific ejection recipe may need adjusting when elements such as the orbit or satellite density profile are changed significantly, our examples suggest that model tidal streams can be quickly and accurately generated by models of this general type for use in Bayesian sampling. [ABSTRACT FROM AUTHOR]

We present the conditional H  i (neutral hydrogen) mass function (HIMF) conditioned on observed optical properties, M r (r -band absolute magnitude), and C ur (u − r colour), for a sample of 7709 galaxies from Arecibo Legacy Fast ALFA (40 per cent data release – α.40) which overlaps with a common volume in SDSS DR7. Based on the conditional HIMF, we find that the luminous red, luminous blue, and faint blue populations dominate the total HIMF at the high-mass end, knee, and the low-mass end, respectively. We use the conditional HIMF to derive the underlying distribution function of ΩH  i (H  i density parameter), p (ΩH  i ), in the colour–magnitude plane of galaxies. The distribution, p (ΩH  i ), peaks in the blue cloud at |$\mathit{ M_{{r}}}^{\text{max}}=-19.25, \mathit{ C_{{ur}}}^{\text{max}}=1.44$| but is skewed. It has a long tail towards faint blue galaxies, and luminous red galaxies. We argue that p (ΩH  i ) can be used to reveal the underlying relation between cold gas, stellar mass, and the star formation rate in an unbiased way, that is, the derived relation does not suffer from survey or sample selection. [ABSTRACT FROM AUTHOR]

The 'red supergiant (RSG) problem' describes the claim that the brightest RSG progenitors to Type II-P supernovae (SNe) are significantly fainter than RSGs in the field. This mismatch has been interpreted by several authors as being a manifestation of the mass threshold for the production of black holes (BHs), such that stars with initial masses above a cut-off of M hi = 17 M⊙ and below 25 M⊙ will die as RSGs, but with no visible SN explosion as the BH is formed. However, we have previously cautioned that this cut-off is more likely to be higher and has large uncertainties (⁠|$M_{\rm hi}=19^{+4}_{-2}\,\mathrm{ M}_{\odot }$|⁠), meaning that the statistical significance of the RSG problem is less than 2σ. Recently, Kochanek has claimed that our work is statistically flawed, and with his analysis has argued that the upper mass cut-off is as low as M hi = 15.7 ± 0.8 M⊙, giving the RSG problem a significance of >10σ. In this letter, we show that Kochanek's low cut-off is caused by a statistical misinterpretation, and the associated fit to the progenitor mass spectrum can be ruled out at the 99.6 per cent confidence level. Once this problem is remedied, Kochanek's best fit becomes |$M_{\rm hi} =19^{+4}_{-2}\,\mathrm{ M}_{\odot }$|⁠ , in excellent agreement with our work. Finally, we argue that, in the search for an RSG 'vanishing' as it collapses directly to a BH, any such survey would have to operate for decades before the absence of any such detection became statistically significant. [ABSTRACT FROM AUTHOR]

The star formation main sequence (SFMS) is a tight relation between the galaxy star formation rate (SFR) and its total stellar mass (M ⋆). Early-type galaxies (ETGs) are often considered as low-SFR outliers of this relation. We study, for the first time, the separated distribution in the SFR versus M ⋆ of bulges and discs of 49 ETGs from the CALIFA survey. This is achieved using c2d , a new code to perform spectrophotometric decompositions of integral field spectroscopy data cubes. Our results reflect that: (i) star formation always occurs in the disc component and not in bulges; (ii) star-forming discs in our ETGs are compatible with the SFMS defined by star-forming galaxies at z ∼ 0; (iii) the star formation is not confined to the outskirts of discs, but it is present at all radii (even where the bulge dominates the light); (iv) for a given mass, bulges exhibit lower sSFR than discs at all radii; and (v) we do not find a deficit of molecular gas in bulges with respect to discs for a given mass in our ETGs. We speculate our results favour a morphological quenching scenario for ETGs. [ABSTRACT FROM AUTHOR]

Double Periodic Variables (DPVs) are hot Algols showing a long photometric cycle of uncertain origin. We report the discovery of changes in the orbital light curve of OGLE-LMC-DPV-097 which depend on the phase of its long photometric cycle. During the ascending branch of the long cycle the brightness at the first quadrature is larger than during the second quadrature, during the maximum of the long cycle the brightness is basically the same at both quadratures, during the descending branch the brightness at the second quadrature is larger than during the first quadrature, and during the minimum of the long cycle the secondary minimum disappears. We model the light curve at different phases of the long cycle and find that the data are consistent with changes in the properties of the accretion disc and two disc spots. The disc's size and temperature change with the long-cycle period. We find a smaller and hotter disc at minimum, and larger and cooler disc at maximum. The spot temperatures, locations, and angular sizes also show variability during the long cycle. [ABSTRACT FROM AUTHOR]

The origin of high-redshift quasars and their supermassive black hole engines is unclear. One promising solution is the collapse of a primordial supermassive star. Observational confirmation of this scenario may be challenging, but a general relativistic instability supernova provides one avenue for such. Previous studies have found that a general relativistic instability supernova has a potentially decades-long plateau phase visible to JWST at high redshift. In this work, we examine stars with mass just below the general relativistic instability supernova mass range. These stars pulsate, ejecting a portion of their envelopes. They then contract quasi-statically back to an equilibrium temperature, at which point they again become unstable and pulsate once more. Because each pulse consumes a small amount of the available nuclear fuel, there exists the possibility of multiple pulsations. We present simulations of the contracting phase, the pulsation, and the light-curve phase. We find that the lower mass pulsating models are even brighter than the higher mass supernovae because the pulsations occur in the late helium burning phase when the stars have extremely large radii. The fact that the pulsations are more luminous and occur in a wider mass range than the supernovae bodes well for observation. [ABSTRACT FROM AUTHOR]

Stars that plunge into the centre of a galaxy are tidally perturbed by a supermassive black hole (SMBH), with closer encounters resulting in larger perturbations. Exciting these tides comes at the expense of the star's orbital energy, which leads to the naive conclusion that a smaller pericentre (i.e. a closer encounter between the star and SMBH) always yields a more tightly bound star to the SMBH. However, once the pericentre distance is small enough that the star is partially disrupted, morphological asymmetries in the mass lost by the star can yield an increase in the orbital energy of the surviving core, resulting in its ejection – not capture – by the SMBH. Using smoothed particle hydrodynamics simulations, we show that the combination of these two effects – tidal excitation and asymmetric mass-loss – results in a maximum amount of energy lost through tides of |$\sim 2.5{{\ \rm per\ cent}}$| of the binding energy of the star, which is significantly smaller than the theoretical maximum of the total stellar binding energy. This result implies that stars that are repeatedly partially disrupted by SMBHs many (≳10) times on short-period orbits (≲few years), as has been invoked to explain the periodic nuclear transient ASASSN-14ko and quasi-periodic eruptions, must be bound to the SMBH through a mechanism other than tidal capture, such as a dynamical exchange (i.e. Hills capture). [ABSTRACT FROM AUTHOR]

Using early-release data from the JWST, Mowla et al. and Claeyssens et al. recently measured various properties for gravitationally lensed compact sources ('sparkles') around the 'Sparkler' galaxy at a redshift of 1.378 (a look-back time of 9.1 Gyr). Here, we focus on the Mowla et al. as they were able to break the age-metallicity degeneracy and derive independent ages, metallicities, and extinctions for each source. They identified five metal-rich, old Globular cluster (GC) candidates (with formation ages up to ∼13 Gyr). We examine the age–metallicity relation (AMR) for the GC candidates and other Sparkler compact sources. The Sparkler galaxy, which has a current estimated stellar mass of 109 M⊙, is compared to the Large Magellanic Cloud (LMC), the disrupted dwarf galaxy Gaia –Enceladus and the Milky Way (MW). The Sparkler galaxy appears to have undergone very rapid chemical enrichment in the first few hundred Myr after formation, with its GC candidates similar to those of the MW's metal-rich subpopulation. We also compare the Sparkler to theoretical AMRs and formation ages from the E-MOSAICS simulation, finding the early formation age of its GCs to be in some tension with these predictions for MW-like galaxies. The metallicity of the Sparkler's star-forming regions are more akin to a galaxy of stellar mass ≥ 1010.5 M⊙, that is, at the top end of the expected mass growth over 9.1 Gyr of cosmic time. We conclude that the Sparkler galaxy may represent a progenitor of a MW-like galaxy, even including the ongoing accretion of a satellite galaxy. [ABSTRACT FROM AUTHOR]

We infer the expected detection number of pair instability supernovae (PISNe) during the operation of the Euclid space telescope based on binary population models. Our models reproduce the global maximum at the primary BH mass of ∼9–10 M⊙ and the overall gradient of the primary BH mass distribution in the binary BH merger rate consistent with recent observations. We consider different PISN conditions depending on the 12C(α, γ)16O reaction rate. The fiducial and 3σ models adopt the standard and 3σ smaller reaction rates, respectively. Our fiducial model predicts that Euclid detects several hydrogen-poor PISNe. For the 3σ model, detection of ∼1 hydrogen-poor PISN by Euclid is expected if the stellar mass distribution extends to M max  = 600 M⊙, but the expected number becomes significantly smaller if M max  = 300 M⊙. We may be able to distinguish the fiducial and 3σ models by the observed PISN rate. This will help us to constrain the origin of binary BHs and the reaction rate, although there remains a degeneracy between M max  and the reaction rate. PISN ejecta mass estimates from light curves and spectra obtained by follow-up observations would be important to disentangle the degeneracy. [ABSTRACT FROM AUTHOR]

We present a first-look analysis of the JWST ERO data in the SMACS J0723.3-7327 cluster field. We begin by reporting 10 new spectroscopic redshifts from λobs = 1.8–5.2 μm NIRSpec medium-resolution (R  = λ/Δλ = 1000) data. These are determined via multiple high-SNR emission line detections with five objects at 1 < z < 3 displaying multiple rest-frame near-infrared Hydrogen Paschen lines, and five objects at 5 < z < 9 displaying rest-frame optical Oxygen and Hydrogen Balmer lines. For the five higher-redshift galaxies we extract fluxes in six NIRCam bands spanning λobs = 0.8–5 μm and perform spectral energy distribution fitting in combination with existing HST photometry. The 7 < z < 9 objects exhibit a U-shaped pattern across the F 277 W, F 356 W , and F 444 W bands, indicating a Balmer break seen in emission (Balmer jump) and high-equivalent-width [O  iii ] emission. This indicates an extremely young stellar population with the bulk of the current mass having formed within the past 10 Myr. We report robust stellar masses and mean stellar ages from our spectral fitting with the four z > 6 galaxies exhibiting low-stellar masses from log10 (M */M⊙) = 7.1–8.2, and correspondingly young mean stellar ages of only a few Myr. This work highlights the critical importance of combining large upcoming NIRCam surveys with NIRSpec follow-up to measure the spectroscopic redshifts necessary to robustly constrain physical parameters. [ABSTRACT FROM AUTHOR]

A wealth of extragalactic populations completely missed at UV-optical wavelengths has been identified in the last decade, combining the deepest HST and Spitzer observations. These dark sources are thought to be dusty and star-forming systems at 3 < z < 5, and major contributors to the stellar mass build up. In this letter, we report an investigation of the deep JWST survey in the SMACS0723 cluster, analysing NIRCam and MIRI images. We search for sources in the F444W band that are undetected in the F200W catalogues. We characterize the properties of these sources via detailed Spectral Energy Distribution (SED) modelling, accounting for a wide set of parameters and star formation histories, after a careful determination of their photometry. Among a robust sample of 20 candidates, we identify a mixed population of very red sources. We highlight the identification of evolved systems, with stellar masses M * ∼ 109–11 M⊙ at 8 < z < 13 characterized by unexpectedly important dust content at those epochs (AV up to ∼5.8 mag), challenging current model predictions. We further identify an extremely red source (F200W-F440W ∼ 7 mag) that can be reproduced only by the spectrum of a passive, quenched galaxy of M * ∼ 1011.56 M⊙ at z  ∼ 5, filled of dust (AV  ∼ 5 mag). [ABSTRACT FROM AUTHOR]

We report the detection of the ground state rotational emission of ammonia, ortho-NH3 (JK  = 10 → 00) in a gravitationally lensed intrinsically hyperluminous star-bursting galaxy at z  = 2.6. The integrated line profile is consistent with other molecular and atomic emission lines which have resolved kinematics well modelled by a 5 kpc-diameter rotating disc. This implies that the gas responsible for NH3 emission is broadly tracing the global molecular reservoir, but likely distributed in pockets of high density (n ≳ 5 × 104 cm−3). With a luminosity of 2.8 × 106 L⊙, the NH3 emission represents 2.5 × 10−7 of the total infrared luminosity of the galaxy, comparable to the ratio observed in the Kleinmann–Low nebula in Orion and consistent with sites of massive star formation in the Milky Way. If |$L_{\rm NH_3}/L_{\rm IR}$| serves as a proxy for the 'mode' of star formation, this hints that the nature of star formation in extreme starbursts in the early Universe is similar to that of Galactic star-forming regions, with a large fraction of the cold interstellar medium in this state, plausibly driven by a storm of violent disc instabilities in the gas-dominated disc. This supports the 'full of Orions' picture of star formation in the most extreme galaxies seen close to the peak epoch of stellar mass assembly. [ABSTRACT FROM AUTHOR]

Several authors have reported that the dynamical masses of massive compact galaxies (M* ≳ 1011 M☉, re ~ 1 kpc), computed as Mdyn = 5.0 σ² e re/G, are lower than their stellar masses M*. In a previous study from our group, the discrepancy is interpreted as a breakdown of the assumption of homology that underlie the Mdyn determinations. Here, we present new spectroscopy of six redshift z ≈ 1.0 massive compact ellipticals from the Extended Groth Strip, obtained with the 10.4 m Gran Telescopio Canarias. We obtain velocity dispersions in the range 161-340 km s-1. As found by previous studies of massive compact galaxies, our velocity dispersions are lower than the virial expectation, and all of our galaxies show Mdyn < M* (assuming a Salpeter initial mass function). Adding data from the literature, we build a sample covering a range of stellar masses and compactness in a narrow redshift range z ≈ 1.0. This allows us to exclude systematic effects on the data and evolutionary effects on the galaxy population, which could have affected previous studies. We confirm that mass discrepancy scales with galaxy compactness. We use the stellar mass plane (M*, σe, re) populated by our sample to constrain a generic evolution mechanism. We find that the simulations of the growth of massive ellipticals due to mergers agree with our constraints and discard the assumption of homology. [ABSTRACT FROM AUTHOR]

We compare the surface brightness profile and morphology of the Galactic Centre Excess (GCE) identified in wide-angle γ-ray maps from the Fermi -Large Area Telescope (LAT) to dark matter annihilation predictions derived from high-resolution Λ cold dark matter magnetohydrodynamic simulations of galaxy formation. These simulations produce isolated, disc-dominated galaxies with structure, stellar populations, gas content, and stellar and halo masses comparable to those of the Milky Way. For a specific choice of annihilation cross-section, they agree well with the Fermi -LAT data over the full observed angular range, 1°–15°, whereas their dark-matter-only counterparts, lacking any compression of the inner halo by the gravitational effects of the baryons, fail to predict emission as centrally concentrated as observed. These results provide additional support to the hypothesis that the GCE is produced by annihilating dark matter. If, however, it is produced by a different mechanism, they imply a strong upper limit on annihilation rates, which can be translated into upper limits on the expected γ-ray flux not only from the inner Galaxy, but also from any substructure, with or without stars, in the Galactic halo. [ABSTRACT FROM AUTHOR]

The concentration – virial mass relation is a well-defined trend that reflects the formation of structure in an expanding universe. Numerical simulations reveal a marked correlation that depends on the collapse time of dark matter haloes and their subsequent assembly history. However, observational constraints are mostly limited to the massive end via X-ray emission of the hot diffuse gas in clusters. An alternative approach, based on gravitational lensing over galaxy scales, revealed an intriguingly high concentration at Milky Way-sized haloes. This letter focuses on the robustness of these results by adopting a bootstrapping approach that combines stellar and lensing mass profiles. We also apply the identical methodology to simulated haloes from eagle to assess any systematic. We bypass several shortcomings of ensemble type lens reconstruction and conclude that the mismatch between observed and simulated concentration–to–virial–mass relations are robust, and need to be explained either invoking a lensing-related sample selection bias, or a careful investigation of the evolution of concentration with assembly history. For reference, at a halo mass of 1012M⊙, the concentration of observed lenses is c |$_{12}\, \sim 40\ \pm$| 5, whereas simulations give c |$_{12}\, \sim 15\ \pm$| 1. [ABSTRACT FROM AUTHOR]

We present a simple model in which the bullets that produce the 'Orion fingers' (ejected by the BN/KL object) are interpreted as protoplanets or low-mass protostars in orbit around a high-mass star that has a supernova explosion. As the remnant of the SN explosion has only a small fraction of the mass of the pre-supernova star, the orbiting objects then move away in free trajectories, preserving their orbital velocity at the time of release. We show that a system of objects arranged in approximately coplanar orbits results in trajectories with morphological and kinematical characteristics resembling the Orion fingers. We show that, under the assumption of constant velocity motions, the positions of the observed heads of the fingers can be used to reconstruct the properties of the orbital structure from which they originated, resulting in a compact disc with an outer radius of ∼2.4 au. [ABSTRACT FROM AUTHOR]

The examination of long-term (1979–2020) photometric observations of SS433 enabled us to discover a non-zero orbital eccentricity of e  = 0.05 ± 0.01. We have also found evidence for a secular increase in the orbital period at a rate of |$\dot{P}_\mathrm{b}=(1.0\pm 0.3)\times 10^{-7}$|  s s−1. The binary orbital period increase rate makes it possible to improve the estimate of the binary mass ratio q  = M X/ M V > 0.8, where M X and M V are the masses of the relativistic object and the optical star, respectively. For an optical star mass of 10 M⊙, the mass of the relativistic object (a black hole) is M X > 8 M⊙. A neutron star in SS433 is reliably excluded because in that case the orbital period should decrease, in contradiction to observations. The derived value of |$\dot{P}_\mathrm{b}$| sets a lower limit on the mass-loss rate in the Jeans mode from the binary system ≳7 × 10−6 M⊙ yr−1. The discovered orbital ellipticity of SS433 is consistent with the model of the slaved accretion disc tracing the precession of the misaligned optical star's rotational axis. [ABSTRACT FROM AUTHOR]

The scaling relation between stellar mass (M *) and physical effective radius (r e) has been well studied using wide spectroscopic surveys. However, these surveys suffer from severe surface brightness incompleteness in the dwarf galaxy regime, where the relation is poorly constrained. In this study, I use a Bayesian empirical model to constrain the power-law exponent β of the M *– r e relation for late-type dwarfs (⁠|$10^{7} \le$| M */M⊙ |$\le 10^{9}$|⁠) using a sample of 188 isolated low surface brightness (LSB) galaxies, accounting for observational incompleteness. Surprisingly, the best-fitting model (β = 0.40 ± 0.07) indicates that the relation is significantly steeper than would be expected from extrapolating canonical models into the dwarf galaxy regime. Nevertheless, the best fitting M*–r e relation closely follows the distribution of known dwarf galaxies. These results indicate that extrapolated canonical models overpredict the number of large dwarf (i.e. LSB) galaxies, including ultra-diffuse galaxies (UDGs), explaining why they are overproduced by some semi-analytic models. The best-fitting model also constrains the power-law exponent of the physical size distribution of UDGs to |$n\mathrm{[dex^{-1}]}\propto r_{\mathrm{ e}}^{3.54\pm 0.33}$|⁠ , consistent to within 1σ of the corresponding value in cluster environments and with the theoretical scenario in which UDGs occupy the high-spin tail of the normal dwarf galaxy population. [ABSTRACT FROM AUTHOR]

We report the discovery of a very dense jet-like fast molecular outflow surrounded by a wide-angle wind in a massive young stellar object (MYSO) G18.88MME (stellar mass ∼8 M⊙) powering an extended green object G18.89−0.47. Four cores MM1–4 are identified in the Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum map (resolution |${\sim} 0.8\, \mathrm { arcsec}$|⁠) towards G18.88MME, and are seen at the centre of the emission structure (extent ∼0.3 pc × 0.2 pc) detected in the ALMA map. G18.88MME is embedded in the core MM1 (mass ∼13–18 M⊙), where no radio continuum emission is detected. The molecular outflow centred at MM1 is investigated in the SiO(5–4), HC3N(24–23) and 13CO(2–1) lines. The detection of HC3N in the outflow is rare in MYSOs and indicates its very high density. The position–velocity diagrams display a fast narrow outflow (extent ∼28 000 AU) and a slower wide-angle more extended outflow towards MM1, and both of these components show a transverse velocity gradient indicative of a possible rotation. All these observed features together make G18.88MME as a unique object for studying the unification of the jet-driven and wind-driven scenarios of molecular outflows in MYSOs. [ABSTRACT FROM AUTHOR]

White dwarf stars are a well-established tool for studying Galactic stellar populations. Two white dwarfs in a tight binary system offer us an additional messenger – gravitational waves – for exploring the Milky Way and its immediate surroundings. Gravitational waves produced by double white dwarf (DWD) binaries can be detected by the future Laser Interferometer Space Antenna (LISA). Numerous and widespread DWDs have the potential to probe shapes, masses, and formation histories of the stellar populations in the Galactic neighbourhood. In this work we outline a method for estimating the total stellar mass of Milky Way satellite galaxies based on the number of DWDs detected by LISA. To constrain the mass we perform a Bayesian inference using binary population synthesis models and considering the number of detected DWDs associated with the satellite and the measured distance to the satellite as the only inputs. Based on a fiducial binary population synthesis model we find that for large satellites the stellar masses can be recovered to within (1) a factor 2 if the star formation history (SFH) is known and (2) an order of magnitude when marginalizing over different SFH models. For smaller satellites we can place upper limits on their stellar mass. Gravitational wave observations can provide mass measurements for large satellites that are comparable, and in some cases more precise, than standard electromagnetic observations. [ABSTRACT FROM AUTHOR]

We report the discovery of BOSS-EUVLG1 at z  = 2.469, by far the most luminous, almost un-obscured star-forming galaxy known at any redshift. First classified as a QSO within the Baryon Oscillation Spectroscopic Survey, follow-up observations with the Gran Telescopio Canarias reveal that its large luminosity, M UV ≃ −24.40 and log(L Lyα/erg s–1) ≃ 44.0, is due to an intense burst of star formation, and not to an active galactic nucleus or gravitational lensing. BOSS-EUVLG1 is a compact (r eff ≃ 1.2 kpc), young (4–5 Myr) starburst with a stellar mass log(M */M⊙) = 10.0 ± 0.1 and a prodigious star formation rate of ≃1000 M⊙ yr−1. However, it is metal- and dust-poor [12 + log(O/H) = 8.13 ± 0.19, E (B – V) ≃ 0.07, log(L IR/ L UV) < −1.2], indicating that we are witnessing the very early phase of an intense starburst that has had no time to enrich the ISM. BOSS-EUVLG1 might represent a short-lived (<100 Myr), yet important phase of star-forming galaxies at high redshift that has been missed in previous surveys. Within a galaxy evolutionary scheme, BOSS-EUVLG1 could likely represent the very initial phases in the evolution of massive quiescent galaxies, even before the dusty star-forming phase. [ABSTRACT FROM AUTHOR]

It has been established for decades that rotation curves deviate from the Newtonian gravity expectation given baryons alone below a characteristic acceleration scale |$g_{\dagger }\sim 10^{-8}\, \rm {cm\, s^{-2}}$|⁠ , a scale promoted to a new fundamental constant in MOND. In recent years, theoretical and observational studies have shown that the star formation efficiency (SFE) of dense gas scales with surface density, SFE ∼ Σ/Σcrit with |$\Sigma _{\rm crit} \sim \langle \dot{p}/m_{\ast }\rangle /(\pi \, G)\sim 1000\, \rm {M_{\odot }\, pc^{-2}}$| (where |$\langle \dot{p}/m_{\ast }\rangle$| is the momentum flux output by stellar feedback per unit stellar mass in a young stellar population). We argue that the SFE, more generally, should scale with the local gravitational acceleration, i.e. that SFE |${\sim}g_{\rm tot}/g_{\rm crit}\equiv (G\, M_{\rm tot}/R^{2}) / \langle \dot{p}/m_{\ast }\rangle$|⁠ , where M tot is the total gravitating mass and |$g_{\rm crit}=\langle \dot{p}/m_{\ast }\rangle = \pi \, G\, \Sigma _{\rm crit} \approx 10^{-8}\, \rm {cm\, s^{-2}} \approx \mathit{ g}_{\dagger }$|⁠. Hence, the observed g † may correspond to the characteristic acceleration scale above which stellar feedback cannot prevent efficient star formation, and baryons will eventually come to dominate. We further show how this may give rise to the observed acceleration scaling |$g_{\rm obs}\sim (g_{\rm baryon}\, g_{\dagger })^{1/2}$| (where g baryon is the acceleration due to baryons alone) and flat rotation curves. The derived characteristic acceleration g † can be expressed in terms of fundamental constants (gravitational constant, proton mass, and Thomson cross-section): |$g_{\dagger }\sim 0.1\, G\, m_{\mathrm{ p}}/\sigma _{\rm T}$|⁠. [ABSTRACT FROM AUTHOR]

Quenched massive spiral galaxies have attracted great attention recently, as more data are available to constrain their environment and cold gas content. However, the quenching mechanism is still uncertain, as it depends on the mass range and baryon budget of the galaxy. In this letter, we report the identification of a rare population of very massive, quenched spiral galaxies with stellar mass ≳1011 M⊙ and halo mass ≳1013 M⊙ from the Sloan Digital Sky Survey at redshift z ∼ 0.1. Our CO observations using the IRAM (Institute for Radio Astronomy in the Millimeter Range) 30-m telescope show that these galaxies contain only a small amount of molecular gas. Similar galaxies are also seen in the state-of-the-art semi-analytical models and hydrodynamical simulations. It is found from these theoretical models that these quenched spiral galaxies harbour massive black holes, suggesting that feedback from the central black holes has quenched these spiral galaxies. This quenching mechanism seems to challenge the popular scenario of the co-evolution between massive black holes and massive bulges. [ABSTRACT FROM AUTHOR]

We present a comprehensive test of the relation between stellar and total masses in galaxies as predicted by popular models based on abundance matching (AM) techniques. We use the 'Spectroscopy and H -band Imaging of Virgo cluster galaxies' (SHIVir) survey with photometric and dynamical profiles for 190 Virgo cluster galaxies to establish a relation between the stellar and dynamical masses measured within the isophotal radius r 23.5. Various dark matter and galaxy scaling relations are combined with results from the NIHAO (Numerical Investigation of Hundred Astrophysical Objects) suite of hydrodynamical simulations to recast AM predictions in terms of these observed quantities. Our results are quite insensitive to the exact choice of dark matter profile and halo response to baryon collapse. We find that theoretical models reproduce the slope and normalization of the observed stellar-to-halo mass relation (SHMR) over more than three orders of magnitude in stellar mass (108 < M */M⊙ < 2 × 1011). However, the scatter of the observed SHMR exceeds that of AM predictions by a factor of ∼5. For systems with stellar masses exceeding 5 × 1010 M⊙, AM overpredicts the observed stellar masses for a given dynamical mass. The latter offset may support previous indications of a different stellar initial mass function in these massive galaxies. Overall, our results support the validity of AM predictions on a wide dynamical range. [ABSTRACT FROM AUTHOR]

The metallicity of star-forming gas in galaxies from the eagle (Evolution and Assembly of GaLaxies and their Environments) simulations increases with stellar mass. Here, we investigate whether the scatter around this relation correlates with morphology and/or stellar kinematics. At redshift z = 0, galaxies with more rotational support have lower metallicities on average when the stellar mass is below M ⋆ ≈ 1010 M⊙. This trend inverts at higher values of M ⋆, when prolate galaxies show typically lower metallicity. At increasing redshifts, the trend between rotational support and metallicity becomes weaker at low stellar mass but more pronounced at high stellar mass. We argue that the secondary dependence of metallicity on stellar kinematics is another manifestation of the observed anticorrelation between metallicity and star formation rate at a given stellar mass. At low masses, such trends seem to be driven by the different star formation histories of galaxies and stellar feedback. At high masses, feedback from active galactic nuclei and galaxy mergers plays a dominant role. [ABSTRACT FROM AUTHOR]

Young massive clusters (YMCs) are the most intense regions of star formation in galaxies. Formulating a model for YMC formation while at the same time meeting the constraints from observations is, however, highly challenging. We show that forming YMCs requires clouds with densities ≳ 100 cm−3 to collide with high velocities (≳ 20 km s−1). We present the first simulations which, starting from moderate cloud densities of ∼100 cm−3, are able to convert a large amount of mass into stars over a time period of around 1 Myr, to produce dense massive clusters similar to those observed. Such conditions are commonplace in more extreme environments, where YMCs are common, but atypical for our Galaxy, where YMCs are rare. [ABSTRACT FROM AUTHOR]

The stellar mass, size, and rotational velocity of galactic discs all grow from redshift ∼2 to the present by amounts that are estimated from observationally derived scaling relations. The product of these three quantities, the angular momentum of stellar discs, is then estimated to grow by a remarkably large factor, between ∼20 and ∼50, whereas other evidences suggest a more moderate increase. This requires that the specific angular momentum of the accreted gas should systematically increase with time while remaining corotational with the disc over most of the last ∼10 Gyr. Thus, the baryonic gas vorticity of the circumgalactic medium appears to emerge as a major driver in galaxy evolution, and this Letter is meant to attract attention on the sheer size of the angular momentum increase and on the need to explore to which extent this can be observed in nature and/or in simulations. [ABSTRACT FROM AUTHOR]

With the spatial resolution of the Atacama Large Millimetre Array (ALMA), dusty galaxies in the distant Universe typically appear as single, compact blobs of dust emission, with a median half-light radius, ≈1 kpc. Occasionally, strong gravitational lensing by foreground galaxies or galaxy clusters has probed spatial scales 1–2 orders of magnitude smaller, often revealing late-stage mergers, sometimes with tantalizing hints of sub-structure. One lensed galaxy in particular, the Cosmic Eyelash at z = 2.3, has been cited extensively as an example of where the interstellar medium exhibits obvious, pronounced clumps, on a spatial scale of ≈100 pc. Seven orders of magnitude more luminous than giant molecular clouds in the local Universe, these features are presented as circumstantial evidence that the blue clumps observed in many z ∼ 2–3 galaxies are important sites of ongoing star formation, with significant masses of gas and stars. Here, we present data from ALMA which reveal that the dust continuum of the Cosmic Eyelash is in fact smooth and can be reproduced using two Sérsic profiles with effective radii, 1.2 and 4.4 kpc, with no evidence of significant star-forming clumps down to a spatial scale of ≈80 pc and a star formation rate of <3 M⊙ yr−1. [ABSTRACT FROM AUTHOR]

An ultraluminous X-ray source (ULX) in NGC 5252 has been known as a strong candidate for an off-nuclear intermediate-mass black hole (IMBH). We present near-infrared imaging data of the ULX obtained with the William Herschel Telescope. Using this data we estimate a stellar mass associated with the ULX of ≈107.9 ± 0.1 |$\, \mathrm{M}_\odot$|⁠ , suggesting that it could be (the remnant of) a dwarf galaxy that is in the process of merging with NGC 5252. Based on a correlation between the mass of the central black hole (BH) and host galaxy, the ULX is powered by a 105  |$\, \mathrm{M}_\odot$| BH. Alternatively, if the BH mass is ≈106 |$\, \mathrm{M}_\odot$| or larger, the host galaxy of the ULX must have been heavily stripped during the merger. The ULX K s -band luminosity is two orders of magnitude smaller than that expected from an ordinary active galactic nucleus with the observed [O  iii ] luminosity, which also suggests the ULX lacks a dusty torus. We discuss how these findings provide suggestive evidence that the ULX is hosting an IMBH. [ABSTRACT FROM AUTHOR]

We measure the Lyman continuum (LyC) escape fraction in 54 faint Lyman-alpha emitters (LAEs) at |$z$| ≃ 3.1 in the GOODS-South field. With the average magnitude of R = 26.7 AB (M UV = −18.8 and L ≃ 0.1 L *), these galaxies represent a population of compact young dwarf galaxies. Their properties are likely to resemble those in the galaxies responsible for reionizing the Universe at |$z$| > 6. We do not detect LyC emission in any individual LAEs in the deep HST F336W images, which covers the rest-frame 820 Å. We do not detect the LyC emission of these LAEs in the stacked F336W images either. The 3σ upper limit of LyC escape fractions is |$f_{\rm esc}\lt 14\!-\!32{{\ \rm per\ cent}}$|⁠. However, the high Ly α rest-frame equivalent width (EW), low stellar mass, and UV luminosity of these LAEs suggest that they should have |$f_{\rm esc}\gt 50{{\ \rm per\ cent}}$|⁠. The low LyC escape fraction from this work and other stacking analyses suggests that the LyC-leaking galaxies with |$f_{\rm esc}\gt 50{{\ \rm per\ cent}}$| at |$z$| = 2–3 do not follow the relation between f esc and UV luminosity and Ly α EW derived from typical galaxies at similar redshifts. Therefore, the UV luminosity and Ly α EW are not the best indicators for the LyC escape fraction. [ABSTRACT FROM AUTHOR]

The impact of 2-body scattering on the innermost density profiles of dark matter haloes is well established. We use a suite of cosmological simulations and idealized numerical experiments to show that 2-body scattering is exacerbated in situations where there are two species of unequal mass. This is a consequence of mass segregation and reflects a flow of kinetic energy from the more to less massive particles. This has important implications for the interpretation of galaxy sizes in cosmological hydrodynamic simulations, which nearly always model stars with less massive particles than are used for the dark matter. We compare idealized models as well as simulations from the eagle project that differ only in the mass resolution of the dark matter component, but keep subgrid physics, baryonic mass resolution, and gravitational force softening fixed. If the dark matter particle mass exceeds the mass of stellar particles, then galaxy sizes – quantified by their projected half-mass radii, R50 – increase systematically with time until R50 exceeds a small fraction of the redshift-dependent mean interparticle separation, l (⁠|${\rm R_{50}} \gtrsim 0.05\times l$|⁠). Our conclusions should also apply to simulations that adopt different hydrodynamic solvers, subgrid physics, or adaptive softening, but in that case may need quantitative revision. Any simulation employing a stellar-to-dark matter particle mass ratio greater than unity will escalate spurious energy transfer from dark matter to baryons on small scales. [ABSTRACT FROM AUTHOR]

We present the first chemical evolution model for Enceladus, alias the Gaia Sausage, to investigate the star formation history of one of the most massive satellites accreted by the Milky Way during a major merger event. Our best chemical evolution model for Enceladus nicely fits the observed stellar [α/Fe]–[Fe/H] chemical abundance trends, and reproduces the observed stellar metallicity distribution function, by assuming low star formation efficiency, fast infall time-scale, and mild outflow intensity. We predict a median age for Enceladus stars |$12.33^{+0.92}_{-1.36}$| Gyr, and – at the time of the merger with our Galaxy (≈10 Gyr ago from Helmi et al.) – we predict for Enceladus a total stellar mass M ⋆ ≈ 5 × 109 M |$\odot$| . By looking at the predictions of our best model, we discuss that merger events between the Galaxy and systems like Enceladus may have inhibited the gas accretion on to the Galaxy disc at high redshifts, heating up the gas in the halo. This scenario could explain the extended period of quenching in the star formation activity of our Galaxy about 10 Gyr ago, which is predicted by Milky Way chemical evolution models, in order to reproduce the observed bimodality in [α/Fe]–[Fe/H] between thick- and thin-disc stars. [ABSTRACT FROM AUTHOR]

In this work we investigate the influence of the dynamic state of galaxy clusters on segregation effects and velocity dispersion profiles (VDPs) for a sample of 111 clusters extracted from SDSS-DR7. We find that 73 clusters have Gaussian (G) velocity distribution and 38 clusters have a complex or non-Gaussian (NG) velocity distribution. We also split the G and NG samples into 'active' and 'passive' galaxies, according to their specific star formation rates and stellar masses. Our results indicate a strong spatial segregation between active and passive galaxies both in G and NG systems, with passive galaxies being more central. We also found that the passive population in G systems is the only family with lower velocity dispersions for the brightest galaxies (M r ≲ −22.75), thus presenting velocity segregation with luminosity. The similarity found between the VDPs of the galaxy populations in NG systems indicates that these sets probably share a similar mix of orbits. We also found a clear evolutionary trend for G systems, with brighter galaxies in massive clusters having flatter VDPs. The scenario emerging from this study suggests a direct relationship between segregation effects, VDPs, and the dynamic state of clusters. [ABSTRACT FROM AUTHOR]

Precise stellar masses and radii can be determined using asteroseismology, but their accuracy must be tested against independent estimates. Using radii derived from Gaia DR2 parallaxes, we test the accuracy of asteroseismic radii for a sample of 93 dwarfs based on both individual frequency fitting and the seismic scaling relations. Radii from frequency fitting are about 1 per cent smaller than Gaia radii on average; however, this difference may be explained by a negative bias of |$30\, \mu\mathrm{as}$| in the Gaia parallaxes. This indicates that the radii derived from frequency fitting are accurate to within 1 per cent. The scaling relations are found to overestimate radii by more than 5 per cent, compared to the Gaia radii, at the highest temperatures. We demonstrate that this offset is reduced to 3 per cent after applying corrections based on model frequencies to the scaling relation for Δν, but only when the model frequencies are corrected for the surface effect. With corrections to Δν, the scaling relation gives radii accurate to about 2–3 per cent for dwarfs in the temperature range 5400–6700 K. The remaining offset at the highest temperatures may indicate the need for a correction to the scaling relation for νmax. [ABSTRACT FROM AUTHOR]

The number of observed dwarf galaxies, with dark matter mass ≲1011 M⊙ in the Milky Way or the Andromeda galaxy does not agree with predictions from the successful ΛCDM paradigm. To alleviate this problem, a suppression of dark matter clustering power on very small scales has been conjectured. However, the abundance of dark matter halos outside our immediate neighbourhood (the Local Group) seem to agree with the ΛCDM–expected abundance. Here we connect these problems to observations of weak lensing cosmic shear, pointing out that cosmic shear can make significant statements about the missing satellites problem in a statistical way. As an example and pedagogical application, we use recent constraints on small-scale power suppression from measurements of the CFHTLenS data. We find that, on average, in a region of ∼Gpc3 there is no significant small-scale power suppression. This implies that suppression of small-scale power is not a viable solution to the 'missing satellites problem' or, alternatively, that on average in this volume there is no 'missing satellites problem' for dark matter masses ≳5 × 109 M⊙. Further analysis of current and future weak lensing surveys will probe much smaller scales, k > 10 h Mpc−1 corresponding roughly to masses M < 109M⊙. [ABSTRACT FROM AUTHOR]

Understanding the physical process responsible for the transport of energy in the core of α Centauri A is of the utmost importance if this star is to be used in the calibration of stellar model physics. Adoption of different parallax measurements available in the literature results in differences in the interferometric radius constraints used in stellar modelling. Further, this is at the origin of the different dynamical mass measurements reported for this star. With the goal of reproducing the revised dynamical mass derived by Pourbaix & Boffin, we modelled the star using two stellar grids varying in the adopted nuclear reaction rates. Asteroseismic and spectroscopic observables were complemented with different interferometric radius constraints during the optimization procedure. Our findings show that best-fitting models reproducing the revised dynamical mass favour the existence of a convective core (≳70 per cent of best-fitting models), a result that is robust against changes to the model physics. If this mass is accurate, then α Centauri A may be used to calibrate stellar model parameters in the presence of a convective core. [ABSTRACT FROM AUTHOR]

In Montero-Dorta et al., we show that luminous red galaxies (LRGs) from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) at z ∼ 0.55 can be divided into two groups based on their star formation histories. So-called fast-growing LRGs assemble 80 per cent of their stellar mass at z ∼ 5, whereas slow-growing LRGs reach the same evolutionary state at z ∼ 1.5. We further demonstrate that these two subpopulations present significantly different clustering properties on scales of ∼1−30 Mpc. Here, we measure the mean halo mass of each subsample using the galaxy–galaxy lensing technique, in the ${\sim }190\deg ^2$ overlap of the LRG catalogue and the CS82 and CFHTLenS shear catalogues. We show that fast- and slow-growing LRGs have similar lensing profiles, which implies that they live in haloes of similar mass: $\log (M_{\rm halo}^{\rm fast}/h^{-1}\mathrm{M}_{{\odot }}) = 12.85^{+0.16}_{-0.26}$ and $\log (M_{\rm halo}^{\rm slow}/h^{-1}\mathrm{M}_{{\odot }}) =12.92^{+0.16}_{-0.22}$. This result, combined with the clustering difference, suggests the existence of galaxy assembly bias, although the effect is too subtle to be definitively proven, given the errors on our current weak-lensing measurement. We show that this can soon be achieved with upcoming surveys like DES. [ABSTRACT FROM AUTHOR]

Initial radial velocity (RV) characterization of the enigmatic planet Kepler-10c suggested a mass of ∼17M⊕, which was remarkably high for a planet with radius 2.32 R⊕; further observations and subsequent analysis hinted at a (possibly much) lower mass, but masses derived using RVs from two different spectrographs (HARPS-N and HIRES) were incompatible at a 3σ level. We demonstrate here how such mass discrepancies may readily arise from suboptimal sampling and/or neglecting to model even a single coherent signal (stellar, planetary or otherwise) that may be present in RVs. We then present a plausible resolution of the mass discrepancy, and ultimately characterize Kepler-10c as having mass 7.37-1.19+1.32M⊕, and mean density 3.14-0.55+0.63 g cm-3. [ABSTRACT FROM AUTHOR]

Theory and observations agree that the accreted stellar haloes (ASHs) of Milky Waylike galaxies display significant scatter. I take advantage of this stochasticity to invert the link between halo assembly history (HAH) and ASH, using mock ASHs corresponding to 750⋀CDM HAHs, sharing a final virial mass ofMh(z=0)=1012.25M☉. Hosts with poor/rich ASHs assemble following orthogonal growth-patterns. Hosts with rich ASHs experience accretion events (AEs) with high virial mass ratios (HVMRs, Ms/Mh≳0.1) at 0.5≲zinfall ≲1.5, in a phase of fast growth. This maximizes the accreted stellar mass under the condition these satellites are disrupted by z = 0. At similar times, hosts with poor ASHs grow slowly through minor mergers, with only very recent HVMR AEs: this results in a globally more abundant satellite population and in distinctive surviving massive satellites (stellar mass logMs, */M☉ ≳9). Several properties of the MilkyWay are in agreement with the predictions of this framework for hosts with poor, concentrated ASHs, including: (i) the recent infall of Sagittarius and Magellanic Clouds, (ii) the likely higher-than-average concentration of its dark halo and (iii) the signatures of fast chemical enrichment of a sizable fraction of its halo stellar populations. [ABSTRACT FROM AUTHOR]

We here derive upper limits on the mass and luminosity of Population III (POPIII) dominated proto-galaxies based on the collapse of primordial gas under the effect of angular momentum loss via Lyα radiation drag and the gas accretion on to a galactic centre. Our model predicts that POPIII-dominated galaxies at z ~ 7 are hosted by haloes with Mh ~ 1.5 x 108-1.1 x 109Mʘ, that they have Lyα luminosities of LLyα ~ 3.0 x 1042-2.1 x 1043 ergs-1, stellar mass of Mstar ~ 0.8 x 105-2.5 x 106 Mʘ and outflowing gas with velocities Vout ~ 40 km s-1 due to Lyα radiation pressure. We show that the POPIII galaxy candidate CR7 violates the derived limits on stellar mass and Lyα luminosity and thus is unlikely to be a POPIII galaxy. POPIII- dominated galaxies at z ~ 7 have Hen line emission that is ~1-3 orders of magnitude lower than that of Lyα, they have high Lyα equivalent width of ≳300 Å and should be found close to bright star-forming galaxies. The Hen 1640 Å line is in comfortable reach of next generation telescopes, like the James Webb Space Telescope (JWST) or Thirty Meter Telescope (TMT). [ABSTRACT FROM AUTHOR]