@article{11508, abstract = {Distant luminous Lyman-α emitters (LAEs) are excellent targets for spectroscopic observations of galaxies in the epoch of reionisation (EoR). We present deep high-resolution (R = 5000) VLT/X-shooter observations, along with an extensive collection of photometric data of COLA1, a proposed double peaked LAE at z = 6.6. We rule out the possibility that COLA1’s emission line is an [OII] doublet at z = 1.475 on the basis of i) the asymmetric red line-profile and flux ratio of the peaks (blue/red=0.31 ± 0.03) and ii) an unphysical [OII]/Hα ratio ([OII]/Hα >  22). We show that COLA1’s observed B-band flux is explained by a faint extended foreground LAE, for which we detect Lyα and [OIII] at z = 2.142. We thus conclude that COLA1 is a real double-peaked LAE at z = 6.593, the first discovered at z >  6. COLA1 is UV luminous (M1500 = −21.6 ± 0.3), has a high equivalent width (EW0,Lyα = 120−40+50 Å) and very compact Lyα emission (r50,Lyα = 0.33−0.04+0.07 kpc). Relatively weak inferred Hβ+[OIII] line-emission from Spitzer/IRAC indicates an extremely low metallicity of Z <  1/20 Z⊙ or reduced strength of nebular lines due to high escape of ionising photons. The small Lyα peak separation of 220 ± 20 km s−1 implies a low HI column density and an ionising photon escape fraction of ≈15 − 30%, providing the first direct evidence that such galaxies contribute actively to the reionisation of the Universe at z >  6. Based on simple estimates, we find that COLA1 could have provided just enough photons to reionise its own ≈0.3 pMpc (2.3 cMpc) bubble, allowing the blue Lyα line to be observed. However, we also discuss alternative scenarios explaining the detected double peaked nature of COLA1. Our results show that future high-resolution observations of statistical samples of double peaked LAEs at z >  5 are a promising probe of the occurrence of ionised regions around galaxies in the EoR.}, author = {Matthee, Jorryt J and Sobral, David and Gronke, Max and Paulino-Afonso, Ana and Stefanon, Mauro and Röttgering, Huub}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: high-redshift / galaxies: formation / dark ages / reionization / first stars / techniques: spectroscopic / intergalactic medium}, publisher = {EDP Sciences}, title = {{Confirmation of double peaked Lyα emission at z = 6.593: Witnessing a galaxy directly contributing to the reionisation of the universe}}, doi = {10.1051/0004-6361/201833528}, volume = {619}, year = {2018}, } @article{11549, abstract = {We investigate the clustering properties of ∼7000 H β + [O III] and [O II] narrowband-selected emitters at z ∼ 0.8–4.7 from the High-z Emission Line Survey. We find clustering lengths, r0, of 1.5–4.0 h−1 Mpc and minimum dark matter halo masses of 1010.7–12.1 M⊙ for our z = 0.8–3.2 H β + [O III] emitters and r0 ∼ 2.0–8.3 h−1 Mpc and halo masses of 1011.5–12.6 M⊙ for our z = 1.5–4.7 [O II] emitters. We find r0 to strongly increase both with increasing line luminosity and redshift. By taking into account the evolution of the characteristic line luminosity, L⋆(z), and using our model predictions of halo mass given r0, we find a strong, redshift-independent increasing trend between L/L⋆(z) and minimum halo mass. The faintest H β + [O III] emitters are found to reside in 109.5 M⊙ haloes and the brightest emitters in 1013.0 M⊙ haloes. For [O II] emitters, the faintest emitters are found in 1010.5 M⊙ haloes and the brightest emitters in 1012.6 M⊙ haloes. A redshift-independent stellar mass dependency is also observed where the halo mass increases from 1011 to 1012.5 M⊙ for stellar masses of 108.5 to 1011.5 M⊙, respectively. We investigate the interdependencies of these trends by repeating our analysis in a Lline−Mstar grid space for our most populated samples (H β + [O III] z = 0.84 and [O II] z = 1.47) and find that the line luminosity dependency is stronger than the stellar mass dependency on halo mass. For L > L⋆ emitters at all epochs, we find a relatively flat trend with halo masses of 1012.5–13 M⊙, which may be due to quenching mechanisms in massive haloes that is consistent with a transitional halo mass predicted by models.}, author = {Khostovan, A A and Sobral, D and Mobasher, B and Best, P N and Smail, I and Matthee, Jorryt J and Darvish, B and Nayyeri, H and Hemmati, S and Stott, J P}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: evolution, galaxies: haloes, galaxies: high-redshift, galaxies: star formation, cosmology: observations, large-scale structure of Universe}, number = {3}, pages = {2999--3015}, publisher = {Oxford University Press}, title = {{The clustering of H β + [O III] and [O II] emitters since z ∼ 5: Dependencies with line luminosity and stellar mass}}, doi = {10.1093/mnras/sty925}, volume = {478}, year = {2018}, } @article{11557, abstract = {Deep narrow-band surveys have revealed a large population of faint Ly α emitters (LAEs) in the distant Universe, but relatively little is known about the most luminous sources (⁠LLyα≳1042.7 erg s−1; LLyα≳L∗Lyα⁠). Here we present the spectroscopic follow-up of 21 luminous LAEs at z ∼ 2–3 found with panoramic narrow-band surveys over five independent extragalactic fields (≈4 × 106 Mpc3 surveyed at z ∼ 2.2 and z ∼ 3.1). We use WHT/ISIS, Keck/DEIMOS, and VLT/X-SHOOTER to study these sources using high ionization UV lines. Luminous LAEs at z ∼ 2–3 have blue UV slopes (⁠β=−2.0+0.3−0.1⁠) and high Ly α escape fractions (⁠50+20−15 per cent) and span five orders of magnitude in UV luminosity (MUV ≈ −19 to −24). Many (70 per cent) show at least one high ionization rest-frame UV line such as C IV, N V, C III], He II or O III], typically blue-shifted by ≈100–200 km s−1 relative to Ly α. Their Ly α profiles reveal a wide variety of shapes, including significant blue-shifted components and widths from 200 to 4000 km s−1. Overall, 60 ± 11  per cent appear to be active galactic nucleus (AGN) dominated, and at LLyα > 1043.3 erg s−1 and/or MUV < −21.5 virtually all LAEs are AGNs with high ionization parameters (log U = 0.6 ± 0.5) and with metallicities of ≈0.5 − 1 Z⊙. Those lacking signatures of AGNs (40 ± 11  per cent) have lower ionization parameters (⁠logU=−3.0+1.6−0.9 and log ξion = 25.4 ± 0.2) and are apparently metal-poor sources likely powered by young, dust-poor ‘maximal’ starbursts. Our results show that luminous LAEs at z ∼ 2–3 are a diverse population and that 2×L∗Lyα and 2×M∗UV mark a sharp transition in the nature of LAEs, from star formation dominated to AGN dominated.}, author = {Sobral, David and Matthee, Jorryt J and Darvish, Behnam and Smail, Ian and Best, Philip N and Alegre, Lara and Röttgering, Huub and Mobasher, Bahram and Paulino-Afonso, Ana and Stroe, Andra and Oteo, Iván}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: active, galaxies: evolution, galaxies: high-redshift, galaxies: ISM, galaxies: starburst, cosmology: observations}, number = {2}, pages = {2817--2840}, publisher = {Oxford University Press}, title = {{The nature of luminous Ly α emitters at z ∼ 2–3: Maximal dust-poor starbursts and highly ionizing AGN}}, doi = {10.1093/mnras/sty782}, volume = {477}, year = {2018}, } @article{11558, abstract = {We present and explore deep narrow- and medium-band data obtained with the Subaru and the Isaac Newton Telescopes in the ∼2 deg2 COSMOS field. We use these data as an extremely wide, low-resolution (R ∼ 20–80) Integral Field Unit survey to slice through the COSMOS field and obtain a large sample of ∼4000 Ly α emitters (LAEs) from z ∼ 2 to 6 in 16 redshift slices (SC4K). We present new Ly α luminosity functions (LFs) covering a comoving volume of ∼108 Mpc3. SC4K extensively complements ultradeep surveys, jointly covering over 4 dex in Ly α luminosity and revealing a global (2.5 < z < 6) synergy LF with α=−1.93+0.12−0.12⁠, log10Φ∗Lyα=−3.45+0.22−0.29 Mpc−3, and log10L∗Lyα=42.93+0.15−0.11 erg s−1. The Schechter component of the Ly α LF reveals a factor ∼5 rise in L∗Lyα and a ∼7 × decline in Φ∗Lyα from z ∼ 2 to 6. The data reveal an extra power-law (or Schechter) component above LLy α ≈ 1043.3 erg s−1 at z ∼ 2.2–3.5 and we show that it is partially driven by X-ray and radio active galactic nucleus (AGN), as their Ly α LF resembles the excess. The power-law component vanishes and/or is below our detection limits above z > 3.5, likely linked with the evolution of the AGN population. The Ly α luminosity density rises by a factor ∼2 from z ∼ 2 to 3 but is then found to be roughly constant (⁠1.1+0.2−0.2×1040 erg s−1 Mpc−3) to z ∼ 6, despite the ∼0.7 dex drop in ultraviolet (UV) luminosity density. The Ly α/UV luminosity density ratio rises from 4 ± 1 per cent to 30 ± 6 per cent from z ∼ 2.2 to 6. Our results imply a rise of a factor of ≈2 in the global ionization efficiency (ξion) and a factor ≈4 ± 1 in the Ly α escape fraction from z ∼ 2 to 6, hinting for evolution in both the typical burstiness/stellar populations and even more so in the typical interstellar medium conditions allowing Ly α photons to escape.}, author = {Sobral, David and Santos, Sérgio and Matthee, Jorryt J and Paulino-Afonso, Ana and Ribeiro, Bruno and Calhau, João and Khostovan, Ali A}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: evolution, galaxies: formation, galaxies: high-redshift, galaxies: luminosity function, mass function, galaxies: statistics}, number = {4}, pages = {4725--4752}, publisher = {Oxford University Press}, title = {{Slicing COSMOS with SC4K: The evolution of typical Ly α emitters and the Ly α escape fraction from z ∼ 2 to 6}}, doi = {10.1093/mnras/sty378}, volume = {476}, year = {2018}, } @article{11555, abstract = {We investigate the morphology of the [C II] emission in a sample of ‘normal’ star-forming galaxies at 5 < z < 7.2 in relation to their UV (rest-frame) counterpart. We use new Atacama Large Millimetre/submillimetre Array (ALMA) observations of galaxies at z ∼ 6–7, as well as a careful re-analysis of archival ALMA data. In total 29 galaxies were analysed, 21 of which are detected in [C II]. For several of the latter the [C II] emission breaks into multiple components. Only a fraction of these [C II] components, if any, is associated with the primary UV systems, while the bulk of the [C II] emission is associated either with fainter UV components, or not associated with any UV counterpart at the current limits. By taking into account the presence of all these components, we find that the L[CII]–SFR (star formation rate) relation at early epochs is fully consistent with the local relation, but it has a dispersion of 0.48 ± 0.07 dex, which is about two times larger than observed locally. We also find that the deviation from the local L[CII]–SFR relation has a weak anticorrelation with the EW(Ly α). The morphological analysis also reveals that [C II] emission is generally much more extended than the UV emission. As a consequence, these primordial galaxies are characterized by a [C II] surface brightness generally much lower than expected from the local Σ[CII]−ΣSFR relation. These properties are likely a consequence of a combination of different effects, namely gas metallicity, [C II] emission from obscured star-forming regions, strong variations of the ionization parameter, and circumgalactic gas in accretion or ejected by these primeval galaxies.}, author = {Carniani, S and Maiolino, R and Amorin, R and Pentericci, L and Pallottini, A and Ferrara, A and Willott, C J and Smit, R and Matthee, Jorryt J and Sobral, D and Santini, P and Castellano, M and De Barros, S and Fontana, A and Grazian, A and Guaita, L}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: evolution, galaxies: high-redshift, galaxies: ISM, galaxies: formation}, number = {1}, pages = {1170--1184}, publisher = {Oxford University Press}, title = {{Kiloparsec-scale gaseous clumps and star formation at z = 5–7}}, doi = {10.1093/mnras/sty1088}, volume = {478}, year = {2018}, } @article{11584, abstract = {Observations show that star-forming galaxies reside on a tight 3D plane between mass, gas-phase metallicity, and star formation rate (SFR), which can be explained by the interplay between metal-poor gas inflows, SFR and outflows. However, different metals are released on different time-scales, which may affect the slope of this relation. Here, we use central, star-forming galaxies with Mstar = 109.0–10.5 M⊙ from the EAGLE hydrodynamical simulation to examine 3D relations between mass, SFR, and chemical enrichment using absolute and relative C, N, O, and Fe abundances. We show that the scatter is smaller when gas-phase α-enhancement is used rather than metallicity. A similar plane also exists for stellar α-enhancement, implying that present-day specific SFRs are correlated with long time-scale star formation histories. Between z = 0 and 1, the α-enhancement plane is even more insensitive to redshift than the plane using metallicity. However, it evolves at z > 1 due to lagging iron yields. At fixed mass, galaxies with higher SFRs have star formation histories shifted towards late times, are more α-enhanced, and this α-enhancement increases with redshift as observed. These findings suggest that relations between physical properties inferred from observations may be affected by systematic variations in α-enhancements.}, author = {Matthee, Jorryt J and Schaye, Joop}, issn = {1745-3933}, journal = {Monthly Notices of the Royal Astronomical Society: Letters}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: abundances, galaxies: evolution, galaxies: formation, galaxies: star formation}, number = {1}, pages = {L34 -- L39}, publisher = {Oxford University Press}, title = {{Star-forming galaxies are predicted to lie on a fundamental plane of mass, star formation rate, and α-enhancement}}, doi = {10.1093/mnrasl/sly093}, volume = {479}, year = {2018}, } @article{11619, abstract = {We report on the confirmation and mass determination of π Men c, the first transiting planet discovered by NASA’s TESS space mission. π Men is a naked-eye (V = 5.65 mag), quiet G0 V star that was previously known to host a sub-stellar companion (π Men b) on a longperiod (Porb = 2091 days), eccentric (e = 0.64) orbit. Using TESS time-series photometry, combined with Gaia data, published UCLES at AAT Doppler measurements, and archival HARPS at ESO-3.6m radial velocities, we found that π Men c is a close-in planet with an orbital period of Porb = 6.27 days, a mass of Mc = 4.52 ± 0.81 M⊕, and a radius of Rc = 2.06 ± 0.03 R⊕. Based on the planet’s orbital period and size, π Men c is a super-Earth located at, or close to, the radius gap, while its mass and bulk density suggest it may have held on to a significant atmosphere. Because of the brightness of the host star, this system is highly suitable for a wide range of further studies to characterize the planetary atmosphere and dynamical properties. We also performed an asteroseismic analysis of the TESS data and detected a hint of power excess consistent with the seismic values expected for this star, although this result depends on the photometric aperture used to extract the light curve. This marginal detection is expected from pre-launch simulations hinting at the asteroseismic potential of the TESS mission for longer, multi-sector observations and/or for more evolved bright stars.}, author = {Gandolfi, D. and Barragán, O. and Livingston, J. H. and Fridlund, M. and Justesen, A. B. and Redfield, S. and Fossati, L. and Mathur, S. and Grziwa, S. and Cabrera, J. and García, R. A. and Persson, C. M. and Van Eylen, V. and Hatzes, A. P. and Hidalgo, D. and Albrecht, S. and Bugnet, Lisa Annabelle and Cochran, W. D. and Csizmadia, Sz. and Deeg, H. and Eigmüller, Ph. and Endl, M. and Erikson, A. and Esposito, M. and Guenther, E. and Korth, J. and Luque, R. and Montañes Rodríguez, P. and Nespral, D. and Nowak, G. and Pätzold, M. and Prieto-Arranz, J.}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, planetary systems / planets and satellites, detection / planets and satellites, fundamental parameters / planets and satellites, terrestrial planets / stars, fundamental parameters}, publisher = {EDP Sciences}, title = {{TESS’s first planet: A super-Earth transiting the naked-eye star π Mensae}}, doi = {10.1051/0004-6361/201834289}, volume = {619}, year = {2018}, } @article{11618, abstract = {Asteroseismology provides global stellar parameters such as masses, radii, or surface gravities using mean global seismic parameters and effective temperature for thousands of low-mass stars (0.8 M⊙ < M < 3 M⊙). This methodology has been successfully applied to stars in which acoustic modes excited by turbulent convection are measured. Other methods such as the Flicker technique can also be used to determine stellar surface gravities, but only works for log g above 2.5 dex. In this work, we present a new metric called FliPer (Flicker in spectral power density, in opposition to the standard Flicker measurement which is computed in the time domain); it is able to extend the range for which reliable surface gravities can be obtained (0.1 < log g < 4.6 dex) without performing any seismic analysis for stars brighter than Kp < 14. FliPer takes into account the average variability of a star measured in the power density spectrum in a given range of frequencies. However, FliPer values calculated on several ranges of frequency are required to better characterize a star. Using a large set of asteroseismic targets it is possible to calibrate the behavior of surface gravity with FliPer through machine learning. This calibration made with a random forest regressor covers a wide range of surface gravities from main-sequence stars to subgiants and red giants, with very small uncertainties from 0.04 to 0.1 dex. FliPer values can be inserted in automatic global seismic pipelines to either give an estimation of the stellar surface gravity or to assess the quality of the seismic results by detecting any outliers in the obtained νmax values. FliPer also constrains the surface gravities of main-sequence dwarfs using only long-cadence data for which the Nyquist frequency is too low to measure the acoustic-mode properties.}, author = {Bugnet, Lisa Annabelle and García, R. A. and Davies, G. R. and Mathur, S. and Corsaro, E. and Hall, O. J. and Rendle, B. M.}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, asteroseismology / methods, data analysis / stars, oscillations}, publisher = {EDP Sciences}, title = {{FliPer: A global measure of power density to estimate surface gravities of main-sequence solar-like stars and red giants}}, doi = {10.1051/0004-6361/201833106}, volume = {620}, year = {2018}, } @article{11620, abstract = {We report the discovery and characterization of HD 89345b (K2-234b; EPIC 248777106b), a Saturn-sized planet orbiting a slightly evolved star. HD 89345 is a bright star (V = 9.3 mag) observed by the K2 mission with 1 min time sampling. It exhibits solar-like oscillations. We conducted asteroseismology to determine the parameters of the star, finding the mass and radius to be 1.12+0.04−0.01M⊙ and 1.657+0.020−0.004R⊙⁠, respectively. The star appears to have recently left the main sequence, based on the inferred age, 9.4+0.4−1.3Gyr⁠, and the non-detection of mixed modes. The star hosts a ‘warm Saturn’ (P = 11.8 d, Rp = 6.86 ± 0.14 R⊕). Radial-velocity follow-up observations performed with the FIbre-fed Echelle Spectrograph, HARPS, and HARPS-N spectrographs show that the planet has a mass of 35.7 ± 3.3 M⊕. The data also show that the planet’s orbit is eccentric (e ≈ 0.2). An investigation of the rotational splitting of the oscillation frequencies of the star yields no conclusive evidence on the stellar inclination angle. We further obtained Rossiter–McLaughlin observations, which result in a broad posterior of the stellar obliquity. The planet seems to confirm to the same patterns that have been observed for other sub-Saturns regarding planet mass and multiplicity, orbital eccentricity, and stellar metallicity.}, author = {Van Eylen, V and Dai, F and Mathur, S and Gandolfi, D and Albrecht, S and Fridlund, M and García, R A and Guenther, E and Hjorth, M and Justesen, A B and Livingston, J and Lund, M N and Pérez Hernández, F and Prieto-Arranz, J and Regulo, C and Bugnet, Lisa Annabelle and Everett, M E and Hirano, T and Nespral, D and Nowak, G and Palle, E and Silva Aguirre, V and Trifonov, T and Winn, J N and Barragán, O and Beck, P G and Chaplin, W J and Cochran, W D and Csizmadia, S and Deeg, H and Endl, M and Heeren, P and Grziwa, S and Hatzes, A P and Hidalgo, D and Korth, J and Mathis, S and Montañes Rodriguez, P and Narita, N and Patzold, M and Persson, C M and Rodler, F and Smith, A M S}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, asteroseismology, planets and satellites: composition, planets and satellites: formation, planets and satellites: fundamental parameters}, number = {4}, pages = {4866--4880}, publisher = {Oxford University Press}, title = {{HD 89345: A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2}}, doi = {10.1093/mnras/sty1390}, volume = {478}, year = {2018}, } @unpublished{11631, abstract = {The recently launched NASA Transiting Exoplanet Survey Satellite (TESS) mission is going to collect lightcurves for a few hundred million of stars and we expect to increase the number of pulsating stars to analyze compared to the few thousand stars observed by the CoRoT, Kepler and K2 missions. However, most of the TESS targets have not yet been properly classified and characterized. In order to improve the analysis of the TESS data, it is crucial to determine the type of stellar pulsations in a timely manner. We propose an automatic method to classify stars attending to their pulsation properties, in particular, to identify solar-like pulsators among all TESS targets. It relies on the use of the global amount of power contained in the power spectrum (already known as the FliPer method) as a key parameter, along with the effective temperature, to feed into a machine learning classifier. Our study, based on TESS simulated datasets, shows that we are able to classify pulsators with a 98% accuracy.}, author = {Bugnet, Lisa Annabelle and García, R. A. and Davies, G. R. and Mathur, S. and Hall, O. J. and Rendle, B. M.}, booktitle = {arXiv}, keywords = {asteroseismology - methods, data analysis - stars, oscillations}, title = {{FliPer: Classifying TESS pulsating stars}}, doi = {10.48550/arXiv.1811.12140}, year = {2018}, }