@article{11585,
  abstract     = {Observations show that star-forming galaxies reside on a tight three-dimensional 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 three-dimensional 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 toward 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},
  issn         = {2397-3366},
  journal      = {Nature Astronomy},
  keywords     = {Astronomy and Astrophysics, galaxies, formation - galaxies, evolution - galaxies, star formation - galaxies, abundances},
  pages        = {984--985},
  publisher    = {Springer Nature},
  title        = {{Differences in galaxy colours are not just about the mass}},
  doi          = {10.1038/s41550-021-01415-y},
  volume       = {5},
  year         = {2021},
}

@article{11533,
  abstract     = {We explore deep rest-frame UV to FIR data in the COSMOS field to measure the individual spectral energy distributions (SED) of the ∼4000 SC4K (Sobral et al.) Lyman α (Ly α) emitters (LAEs) at z ∼ 2–6. We find typical stellar masses of 109.3 ± 0.6 M⊙ and star formation rates (SFR) of SFRSED=4.4+10.5−2.4 M⊙ yr−1 and SFRLyα=5.9+6.3−2.6 M⊙ yr−1, combined with very blue UV slopes of β=−2.1+0.5−0.4⁠, but with significant variations within the population. MUV and β are correlated in a similar way to UV-selected sources, but LAEs are consistently bluer. This suggests that LAEs are the youngest and/or most dust-poor subset of the UV-selected population. We also study the Ly α rest-frame equivalent width (EW0) and find 45 ‘extreme’ LAEs with EW0 > 240 Å (3σ), implying a low number density of (7 ± 1) × 10−7 Mpc−3. Overall, we measure little to no evolution of the Ly α EW0 and scale length parameter (w0), which are consistently high (EW0=140+280−70 Å, w0=129+11−11 Å) from z ∼ 6 to z ∼ 2 and below. However, w0 is anticorrelated with MUV and stellar mass. Our results imply that sources selected as LAEs have a high Ly α escape fraction (fesc,Ly α) irrespective of cosmic time, but fesc,Ly α is still higher for UV-fainter and lower mass LAEs. The least massive LAEs (<109.5 M⊙) are typically located above the star formation ‘main sequence’ (MS), but the offset from the MS decreases towards z ∼ 6 and towards 1010 M⊙. Our results imply a lack of evolution in the properties of LAEs across time and reveals the increasing overlap in properties of LAEs and UV-continuum selected galaxies as typical star-forming galaxies at high redshift effectively become LAEs.},
  author       = {Santos, S and Sobral, D and Matthee, Jorryt J and Calhau, J and da Cunha, E and Ribeiro, B and Paulino-Afonso, A and Arrabal Haro, P and Butterworth, J},
  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: star formation},
  number       = {1},
  pages        = {141--160},
  publisher    = {Oxford University Press},
  title        = {{The evolution of rest-frame UV properties, Ly α EWs, and the SFR–stellar mass relation at z ∼ 2–6 for SC4K LAEs}},
  doi          = {10.1093/mnras/staa093},
  volume       = {493},
  year         = {2020},
}

@article{11539,
  abstract     = {Despite recent progress in understanding Ly α emitters (LAEs), relatively little is known regarding their typical black hole activity across cosmic time. Here, we study the X-ray and radio properties of ∼4000 LAEs at 2.2 < z < 6 from the SC4K survey in the COSMOS field. We detect 254 (⁠6.8per cent±0.4per cent⁠) LAEs individually in the X-rays (S/N > 3) with an average luminosity of 1044.31±0.01ergs−1 and average black hole accretion rate (BHAR) of 0.72±0.01 M⊙ yr−1, consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of 3.2per cent±0.3per cent⁠). The global AGN fraction (⁠8.6per cent±0.4per cent⁠) rises with Ly α luminosity and declines with increasing redshift. For X-ray-detected LAEs, Ly α luminosities correlate with the BHARs, suggesting that Ly α luminosity becomes a BHAR indicator. Most LAEs (⁠93.1per cent±0.6per cent⁠) at 2 < z < 6 have no detectable X-ray emission (BHARs < 0.017 M⊙ yr−1). The median star formation rate (SFR) of star-forming LAEs from Ly α and radio luminosities is 7.6+6.6−2.8 M⊙ yr−1. The black hole to galaxy growth ratio (BHAR/SFR) for LAEs is <0.0022, consistent with typical star-forming galaxies and the local BHAR/SFR relation. We conclude that LAEs at 2 < z < 6 include two different populations: an AGN population, where Ly α luminosity traces BHAR, and another with low SFRs which remain undetected in even the deepest X-ray stacks but is detected in the radio stacks.},
  author       = {Calhau, João and Sobral, David and Santos, Sérgio and Matthee, Jorryt J and Paulino-Afonso, Ana and Stroe, Andra and Simmons, Brooke and Barlow-Hall, Cassandra and Adams, Benjamin},
  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, quasars: supermassive black holes, galaxies: star formation, cosmology: observations, X-rays: galaxies},
  number       = {3},
  pages        = {3341--3362},
  publisher    = {Oxford University Press},
  title        = {{The X-ray and radio activity of typical and luminous Ly α emitters from z ∼ 2 to z ∼ 6: Evidence for a diverse, evolving population}},
  doi          = {10.1093/mnras/staa476},
  volume       = {493},
  year         = {2020},
}

@article{11499,
  abstract     = {Deep optical spectroscopic surveys of galaxies provide a unique opportunity to investigate rest-frame ultra-violet (UV) emission line properties of galaxies at z ∼ 2 − 4.5. Here we combine VLT/MUSE Guaranteed Time Observations of the Hubble Deep Field South, Ultra Deep Field, COSMOS, and several quasar fields with other publicly available data from VLT/VIMOS and VLT/FORS2 to construct a catalogue of He II λ1640 emitters at z ≳ 2. The deepest areas of our MUSE pointings reach a 3σ line flux limit of 3.1 × 10−19 erg s−1 cm−2. After discarding broad-line active galactic nuclei, we find 13 He II λ1640 detections from MUSE with a median MUV = −20.1 and 21 tentative He II λ1640 detections from other public surveys. Excluding Lyα, all except two galaxies in our sample show at least one other rest-UV emission line, with C III] λ1907, λ1909 being the most prominent. We use multi-wavelength data available in the Hubble legacy fields to derive basic galaxy properties of our sample through spectral energy distribution fitting techniques. Taking advantage of the high-quality spectra obtained by MUSE (∼10 − 30 h of exposure time per pointing), we use photo-ionisation models to study the rest-UV emission line diagnostics of the He II λ1640 emitters. Line ratios of our sample can be reproduced by moderately sub-solar photo-ionisation models, however, we find that including effects of binary stars lead to degeneracies in most free parameters. Even after considering extra ionising photons produced by extreme sub-solar metallicity binary stellar models, photo-ionisation models are unable to reproduce rest-frame He II λ1640 equivalent widths (∼0.2 − 10 Å), thus additional mechanisms are necessary in models to match the observed He II λ1640 properties.},
  author       = {Nanayakkara, Themiya and Brinchmann, Jarle and Boogaard, Leindert and Bouwens, Rychard and Cantalupo, Sebastiano and Feltre, Anna and Kollatschny, Wolfram and Marino, Raffaella Anna and Maseda, Michael and Matthee, Jorryt J and Paalvast, Mieke and Richard, Johan and Verhamme, Anne},
  issn         = {1432-0746},
  journal      = {Astronomy & Astrophysics},
  keywords     = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: ISM / galaxies: star formation / galaxies: evolution / galaxies: high-redshift},
  publisher    = {EDP Sciences},
  title        = {{Exploring He II λ1640 emission line properties at z ∼2−4}},
  doi          = {10.1051/0004-6361/201834565},
  volume       = {648},
  year         = {2019},
}

@article{11507,
  abstract     = {Lyman-α (Lyα) is intrinsically the brightest line emitted from active galaxies. While it originates from many physical processes, for star-forming galaxies the intrinsic Lyα luminosity is a direct tracer of the Lyman-continuum (LyC) radiation produced by the most massive O- and early-type B-stars (M⋆ ≳ 10 M⊙) with lifetimes of a few Myrs. As such, Lyα luminosity should be an excellent instantaneous star formation rate (SFR) indicator. However, its resonant nature and susceptibility to dust as a rest-frame UV photon makes Lyα very hard to interpret due to the uncertain Lyα escape fraction, fesc, Lyα. Here we explore results from the CAlibrating LYMan-α with Hα (CALYMHA) survey at z = 2.2, follow-up of Lyα emitters (LAEs) at z = 2.2 − 2.6 and a z ∼ 0−0.3 compilation of LAEs to directly measure fesc, Lyα with Hα. We derive a simple empirical relation that robustly retrieves fesc, Lyα as a function of Lyα rest-frame EW (EW0): fesc,Lyα = 0.0048 EW0[Å] ± 0.05 and we show that it constrains a well-defined anti-correlation between ionisation efficiency (ξion) and dust extinction in LAEs. Observed Lyα luminosities and EW0 are easy measurable quantities at high redshift, thus making our relation a practical tool to estimate intrinsic Lyα and LyC luminosities under well controlled and simple assumptions. Our results allow observed Lyα luminosities to be used to compute SFRs for LAEs at z ∼ 0−2.6 within ±0.2 dex of the Hα dust corrected SFRs. We apply our empirical SFR(Lyα,EW0) calibration to several sources at z ≥ 2.6 to find that star-forming LAEs have SFRs typically ranging from 0.1 to 20 M⊙ yr−1 and that our calibration might be even applicable for the most luminous LAEs within the epoch of re-ionisation. Our results imply high ionisation efficiencies (log10[ξion/Hz erg−1] = 25.4−25.6) and low dust content in LAEs across cosmic time, and will be easily tested with future observations with JWST which can obtain Hα and Hβ measurements for high-redshift LAEs.},
  author       = {Sobral, David and Matthee, Jorryt J},
  issn         = {1432-0746},
  journal      = {Astronomy & Astrophysics},
  keywords     = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: high-redshift / galaxies: star formation / galaxies: statistics / galaxies: evolution / galaxies: formation / galaxies: ISM},
  publisher    = {EDP Sciences},
  title        = {{Predicting Lyα escape fractions with a simple observable: Lyα in emission as an empirically calibrated star formation rate indicator}},
  doi          = {10.1051/0004-6361/201833075},
  volume       = {623},
  year         = {2019},
}

@article{11535,
  abstract     = {We investigate the clustering and halo properties of ∼5000 Ly α-selected emission-line galaxies (LAEs) from the Slicing COSMOS 4K (SC4K) and from archival NB497 imaging of SA22 split in 15 discrete redshift slices between z ∼ 2.5 and 6. We measure clustering lengths of r0 ∼ 3–6 h−1 Mpc and typical halo masses of ∼1011 M⊙ for our narrowband-selected LAEs with typical LLy α ∼ 1042–43 erg s−1. The intermediate-band-selected LAEs are observed to have r0 ∼ 3.5–15 h−1 Mpc with typical halo masses of ∼1011–12 M⊙ and typical LLy α ∼ 1043–43.6 erg s−1. We find a strong, redshift-independent correlation between halo mass and Ly α luminosity normalized by the characteristic Ly α luminosity, L⋆(z). The faintest LAEs (L ∼ 0.1 L⋆(z)) typically identified by deep narrowband surveys are found in 1010 M⊙ haloes and the brightest LAEs (L ∼ 7 L⋆(z)) are found in ∼5 × 1012 M⊙ haloes. A dependency on the rest-frame 1500 Å UV luminosity, MUV, is also observed where the halo masses increase from 1011 to 1013 M⊙ for MUV ∼ −19 to −23.5 mag. Halo mass is also observed to increase from 109.8 to 1012 M⊙ for dust-corrected UV star formation rates from ∼0.6 to 10 M⊙ yr−1 and continues to increase up to 1013 M⊙ in halo mass, where the majority of those sources are active galactic nuclei. All the trends we observe are found to be redshift independent. Our results reveal that LAEs are the likely progenitors of a wide range of galaxies depending on their luminosity, from dwarf-like, to Milky Way-type, to bright cluster galaxies. LAEs therefore provide unique insight into the early formation and evolution of the galaxies we observe in the local Universe.},
  author       = {Khostovan, A A and Sobral, D and Mobasher, B and Matthee, Jorryt J and Cochrane, R K and Chartab, N and Jafariyazani, M and Paulino-Afonso, A and Santos, S and Calhau, J},
  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       = {1},
  pages        = {555--573},
  publisher    = {Oxford University Press},
  title        = {{The clustering of typical Ly α emitters from z ∼ 2.5–6: Host halo masses depend on Ly α and UV luminosities}},
  doi          = {10.1093/mnras/stz2149},
  volume       = {489},
  year         = {2019},
}

@article{11540,
  abstract     = {Observations have revealed that the star formation rate (SFR) and stellar mass (Mstar) of star-forming galaxies follow a tight relation known as the galaxy main sequence. However, what physical information is encoded in this relation is under debate. Here, we use the EAGLE cosmological hydrodynamical simulation to study the mass dependence, evolution, and origin of scatter in the SFR–Mstar relation. At z = 0, we find that the scatter decreases slightly with stellar mass from 0.35 dex at Mstar ≈ 109 M⊙ to 0.30 dex at Mstar ≳ 1010.5 M⊙. The scatter decreases from z = 0 to z = 5 by 0.05 dex at Mstar ≳ 1010 M⊙ and by 0.15 dex for lower masses. We show that the scatter at z = 0.1 originates from a combination of fluctuations on short time-scales (ranging from 0.2–2 Gyr) that are presumably associated with self-regulation from cooling, star formation, and outflows, but is dominated by long time-scale (∼10 Gyr) variations related to differences in halo formation times. Shorter time-scale fluctuations are relatively more important for lower mass galaxies. At high masses, differences in black hole formation efficiency cause additional scatter, but also diminish the scatter caused by different halo formation times. While individual galaxies cross the main sequence multiple times during their evolution, they fluctuate around tracks associated with their halo properties, i.e. galaxies above/below the main sequence at z = 0.1 tend to have been above/below the main sequence for ≫1 Gyr.},
  author       = {Matthee, Jorryt J and Schaye, Joop},
  issn         = {1365-2966},
  journal      = {Monthly Notices of the Royal Astronomical Society},
  keywords     = {Space and Planetary Science, Astronomy and Astrophysics : galaxies: evolution, galaxies: formation, galaxies: star formation, cosmology: theory},
  number       = {1},
  pages        = {915--932},
  publisher    = {Oxford University Press},
  title        = {{The origin of scatter in the star formation rate–stellar mass relation}},
  doi          = {10.1093/mnras/stz030},
  volume       = {484},
  year         = {2019},
}

@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{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{11561,
  abstract     = {We present a sample of ∼1000 emission-line galaxies at z = 0.4–4.7 from the ∼0.7deg2 High-z Emission-Line Survey in the Boötes field identified with a suite of six narrow-band filters at ≈0.4–2.1 μm. These galaxies have been selected on their Ly α (73), [O II] (285), H β/[O III] (387) or H α (362) emission line, and have been classified with optical to near-infrared colours. A subsample of 98 sources have reliable redshifts from multiple narrow-band (e.g. [O II]–H α) detections and/or spectroscopy. In this survey paper, we present the observations, selection and catalogues of emitters. We measure number densities of Ly α, [O II], H β/[O III] and H α and confirm strong luminosity evolution in star-forming galaxies from z ∼ 0.4 to ∼5, in agreement with previous results. To demonstrate the usefulness of dual-line emitters, we use the sample of dual [O II]–H α emitters to measure the observed [O II]/H α ratio at z = 1.47. The observed [O II]/H α ratio increases significantly from 0.40 ± 0.01 at z = 0.1 to 0.52 ± 0.05 at z = 1.47, which we attribute to either decreasing dust attenuation with redshift, or due to a bias in the (typically) fibre measurements in the local Universe that only measure the central kpc regions. At the bright end, we find that both the H α and Ly α number densities at z ≈ 2.2 deviate significantly from a Schechter form, following a power law. We show that this is driven entirely by an increasing X-ray/active galactic nucleus fraction with line luminosity, which reaches ≈100 per cent at line luminosities L ≳ 3 × 1044 erg s−1.},
  author       = {Matthee, Jorryt J and Sobral, David and Best, Philip and Smail, Ian and Bian, Fuyan and Darvish, Behnam and Röttgering, Huub and Fan, Xiaohui},
  issn         = {0035-8711},
  journal      = {Monthly Notices of the Royal Astronomical Society},
  keywords     = {Space and Planetary Science, Astronomy and Astrophysics galaxies, active, galaxies, evolution, galaxies, high-redshift, galaxies, luminosity function, mass function, galaxies: star formation},
  number       = {1},
  pages        = {629--649},
  publisher    = {Oxford University Press},
  title        = {{Boötes-HiZELS: An optical to near-infrared survey of emission-line galaxies at z = 0.4–4.7}},
  doi          = {10.1093/mnras/stx1569},
  volume       = {471},
  year         = {2017},
}

@article{11566,
  abstract     = {While traditionally associated with active galactic nuclei (AGN), the properties of the C II] (λ = 2326 Å), C III] (λ, λ = 1907, 1909 Å) and C IV (λ, λ = 1549, 1551 Å) emission lines are still uncertain as large, unbiased samples of sources are scarce. We present the first blind, statistical study of C II], C III] and C IV emitters at z ∼ 0.68, 1.05, 1.53, respectively, uniformly selected down to a flux limit of ∼4 × 10−17 erg s−1 cm−1 through a narrow-band survey covering an area of ∼1.4 deg2 over COSMOS and UDS. We detect 16 C II], 35 C III] and 17 C IV emitters, whose nature we investigate using optical colours as well as Hubble Space Telescope (HST), X-ray, radio and far-infrared data. We find that z ∼ 0.7 C II] emitters are consistent with a mixture of blue (UV slope β = −2.0 ± 0.4) star-forming (SF) galaxies with discy HST structure and AGN with Seyfert-like morphologies. Bright C II] emitters have individual X-ray detections as well as high average black hole accretion rates (BHARs) of ∼0.1 M⊙ yr−1. C III] emitters at z ∼ 1.05 trace a general population of SF galaxies, with β = −0.8 ± 1.1, a variety of optical morphologies, including isolated and interacting galaxies and low BHAR (<0.02 M⊙ yr−1). Our C IV emitters at z ∼ 1.5 are consistent with young, blue quasars (β ∼ −1.9) with point-like optical morphologies, bright X-ray counterparts and large BHAR (0.8  M⊙ yr−1). We also find some surprising C II], C III] and C IV emitters with rest-frame equivalent widths (EWs) that could be as large as 50–100 Å. AGN or spatial offsets between the UV continuum stellar disc and the line-emitting regions may explain the large EW. These bright C II], C III] and C IV emitters are ideal candidates for spectroscopic follow-up to fully unveil their nature.},
  author       = {Stroe, Andra and Sobral, David and Matthee, Jorryt J and Calhau, João and Oteo, Ivan},
  issn         = {1365-2966},
  journal      = {Monthly Notices of the Royal Astronomical Society},
  keywords     = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: active, galaxies: high-redshift, quasars: emission lines, galaxies: star formation, cosmology: observations},
  number       = {3},
  pages        = {2558--2574},
  publisher    = {Oxford University Press},
  title        = {{A 1.4 deg2 blind survey for C II], C III] and C IV at z ∼ 0.7–1.5 – I. Nature, morphologies and equivalent widths }},
  doi          = {10.1093/mnras/stx1712},
  volume       = {471},
  year         = {2017},
}

@article{11567,
  abstract     = {Recently, the C III] and C IV emission lines have been observed in galaxies in the early Universe (z > 5), providing new ways to measure their redshift and study their stellar populations and active galactic nuclei (AGN). We explore the first blind C II], C III] and C IV survey (z ∼ 0.68, 1.05, 1.53, respectively) presented in Stroe et al. (2017). We derive luminosity functions (LF) and study properties of C II], C III] and C IV line emitters through comparisons to the LFs of H α and Ly α emitters, UV selected star-forming (SF) galaxies and quasars at similar redshifts. The C II] LF at z ∼ 0.68 is equally well described by a Schechter or a power-law LF, characteristic of a mixture of SF and AGN activity. The C III] LF (z ∼ 1.05) is consistent to a scaled down version of the Schechter H α and Ly α LF at their redshift, indicating a SF origin. In stark contrast, the C IV LF at z ∼ 1.53 is well fit by a power-law, quasar-like LF. We find that the brightest UV sources (MUV < −22) will universally have C III] and C IV emission. However, on average, C III] and C IV are not as abundant as H α or Ly α emitters at the same redshift, with cosmic average ratios of ∼0.02–0.06 to H α and ∼0.01–0.1 to intrinsic Ly α. We predict that the C III] and C IV lines can only be truly competitive in confirming high-redshift candidates when the hosts are intrinsically bright and the effective Ly α escape fraction is below 1 per cent. While C III] and C IV were proposed as good tracers of young, relatively low-metallicity galaxies typical of the early Universe, we find that, at least at z ∼ 1.5, C IV is exclusively hosted by AGN/quasars, especially at large line equivalent widths.},
  author       = {Stroe, Andra and Sobral, David and Matthee, Jorryt J and Calhau, João and Oteo, Ivan},
  issn         = {1365-2966},
  journal      = {Monthly Notices of the Royal Astronomical Society},
  keywords     = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: active, galaxies: high redshift, galaxies: luminosity function, mass function, quasars: emission lines, star formation, cosmology: observations},
  number       = {3},
  pages        = {2575--2586},
  publisher    = {Oxford University Press},
  title        = {{A 1.4 deg2 blind survey for C II], C III] and C IV at z ∼ 0.7–1.5 – II. Luminosity functions and cosmic average line ratios}},
  doi          = {10.1093/mnras/stx1713},
  volume       = {471},
  year         = {2017},
}