Rest-frame UV properties of luminous strong gravitationally lensed Lyα emitters from the BELLS GALLERY Survey

Abstract

We present deep rest-frame UV spectroscopic observations using the Gran Telescopio Canarias of six gravitationally lensed Lyα emitters (LAEs) at 2.36 < z < 2.82 selected from the BELLS GALLERY survey. By taking the magnifications into account, we show that LAEs can be as luminous as L Lyα 30 × 10 42 erg s −1 and M UV −23 (AB) without invoking an AGN component, in contrast with previous findings. We measure Lyα rest-frame equivalent widths, EW 0 (Lyα), ranging from 16Å to 50Å and Lyα escape fractions, f esc (Lyα), from 10% to 40%. Large EW 0 (Lyα) and f esc (Lyα) are found predominantly in LAEs showing weak low-ionization ISM absorption (EW 0 1Å) and narrow Lyα profiles ( 300 km s −1 FWHM) with their peak close ( 80 km s −1 ) to their systemic redshifts, suggestive of less scatter from low H i column densities that favours the escape of Lyα photons. We infer stellar metallicities of Z/Z 0.2 in almost all LAEs by comparing the P-Cygni profiles of the wind lines N v1240Å and C iv1549Å with those from stellar synthesis models. We also find a trend between M UV and the velocity offset of ISM absorption lines, such as the most luminous LAEs experience stronger outflows. The most luminous LAEs show star formation rates up to 180 M yr −1 , yet they appear relatively blue (β UV −1.8 to −2.0) showing evidence of little dust attenuation (E(B − V) = 0.10 − 0.14). These luminous LAEs may be particular cases of young starburst galaxies that have had no time to form large amounts of dust. If so, they are ideal laboratories to study the early phase of massive star formation, stellar and dust mass growth, and chemical enrichment histories of starburst galaxies at high-z.

Detection of an ionized gas outflow in the extreme UV-luminous star-forming galaxy BOSS-EUVLG1 at z=2.47

“…BOSS-EUVLG1 is an extreme starburst galaxy with a starforming rate of 955 ± 118 M yr −1 , which can be considered an ultraluminous galaxy based on its UV luminosity (i.e., L 1500Å ∼ 10 12 L ). Its SFR is similar to those measured in high−z (Patrício et al 2016;Marques-Chaves et al 2020b). Red squares: Lyman break galaxies (Pettini et al 2000;Quider et al 2009Quider et al , 2010Dessauges-Zavadsky et al 2010;Marques-Chaves et al 2018).…”

Deciphering stellar metallicities in the early Universe: Case study of a young galaxy at z = 4.77 in the MUSE eXtremely Deep Field

“…Erb et al 2010;Jaskot & Oey 2014;Bosman et al 2019), they are empirically found to trace the systemic redshift in galaxies at z ≈ 2 − 3 (e.g. Shapley et al 2003;Erb et al 2010;Steidel et al 2016;Vanzella et al 2018;Marques-Chaves et al 2020). Wind models from Prochaska et al (2011) indicate that the detection of non-resonant emission suggest that there is little attenuation and that outflows only partially cover the source, particularly as we find that the spatial profiles of the non-resonant lines are similar to that of the UV continuum.…”

The discovery of the most UV-Lya luminous star-forming galaxy: a young, dust- and metal-poor starburst with QSO-like luminosities

“…The most striking property of BOSS-EUVLG1 is its brightness, and corresponding large luminosities at z 2.469, in both the rest-frame UV continuum (R 20.8) and nebular emission (fluxes in Lyα and Hα above 10 −15 erg s −1 cm −2 , Table 1). Such apparent fluxes are much larger than those observed in typical SFGs (factors ≈ 30; e.g., Reddy & Steidel 2009;Sobral et al 2018a) and are only comparable to those observed in highly magnified lensed systems (e.g., Shu et al 2016;Marques-Chaves et al 2020) or in QSOs (e.g., Pâris et al 2014).…”

“…Instead, the large luminosities arise from a large number of OB stars present in the first stages of an intense burst of star-formation. We compare the wind line profiles of N v and C iv to those obtained with the spectral synthesis code Starburst99 (S99: Leitherer et al 1999) to infer the age and metallicity of the stellar population (details in Marques-Chaves et al 2018, 2020. P-Cygni profiles are well modeled by a Z/Z 1/5 and 4 Myr burst of star formation (Fig.…”