The MUSE Deep Lensed Field on the Hubble Frontier Field MACS J0416

Abstract

Context. A census of faint and tiny star forming complexes at high redshift is key to improving our understanding of reionizing sources, galaxy growth, and the formation of globular clusters. Aims. We present the MUSE Deep Lensed Field (MDLF) program, which is aimed at unveiling the very faint population of high redshift sources that are magnified by strong gravitational lensing and to significantly increase the number of constraints for the lens model. Methods. We describe Deep MUSE observations of 17.1 h of integration on a single pointing over the Hubble Frontier Field galaxy cluster MACS J0416, providing line flux limits down to 2 × 10−19 erg s−1 cm−2 within 300 km s−1 and continuum detection down to magnitude 26, both at the three sigma level at λ = 7000 Å. For point sources with a magnification (μ) greater than 2.5 (7.7), the MLDF depth is equivalent to integrating more than 100 (1000) h in blank fields, as well as complementing non-lensed studies of very faint high-z sources. The source-plane effective area of the MDLF with μ > 6.3 is < 50% of the image-plane field of view. Results. We confirm spectroscopic redshifts for all 136 multiple images of 48 source galaxies at 0.9 < z < 6.2. Within those galaxies, we securely identify 182 multiple images of 66 galaxy components that we use to constrain our lens model. This makes MACS J0416 the cluster with the largest number of confirmed constraints for any strong lens model to date. We identify 116 clumps belonging to background high-z galaxies; the majority of them are multiple images and span magnitude, size, and redshift intervals of [ − 18, −10], [ ∼ 400 − 3] parsec and 1 < z < 6.6, respectively, with the faintest or most magnified ones probing possible single gravitationally bound star clusters. The multiplicity introduced by gravitational lensing allows us, in several cases, to triple the effective integration time up to ∼51 h exposure per single family, leading to a detection limit for unresolved emission lines of a few 10−20 erg s−1 cm−2, after correction for lensing magnification. Ultraviolet high-ionization metal lines (and He IIλ1640) are detected with S/N > 10 for individual objects down to de-lensed magnitudes between 28 and 30. The median stacked spectrum of 33 sources with a median MUV ≃ −17 and ⟨z⟩ = 3.2 (1.7 < z < 3.9) shows high-ionization lines, suggesting that they are common in such faint sources. Conclusions. Deep MUSE observations, in combination with existing HST imaging, allowed us to: (1) confirm redshifts for extremely faint high-z sources; (2) peer into their internal structure to unveil clumps down to 100 − 200 pc scale; (3) in some cases, break down such clumps into star-forming complexes matching the scales of bound star clusters (< 20 pc effective radius); (4) double the number of constraints for the lens model, reaching an unprecedented set of 182 bona-fide multiple images and confirming up to 213 galaxy cluster members. These results demonstrate the power of JWST and future adaptive optics facilities mounted on the Extremely Large Telescopes (e.g., European-ELT Multi-conjugate Adaptive Optics RelaY, MAORY, coupled with the Multi-AO Imaging CamerA for Deep Observations, MICADO) or Very Large Telescope (e.g., MCAO Assisted Visible Imager and Spectrograph, MAVIS) when combined in studies with gravitational telescopes.

Stellar feedback in a clumpy galaxy at z ∼ 3.4

“…Clumps have been detected in rest-frame UV imaging (e.g. Guo et al 2012Guo et al , 2015Guo et al , 2018Livermore et al 2012;Shibuya et al 2016;Soto et al 2017;Dessauges-Zavadsky & Adamo 2018;Messa et al 2019;Vanzella et al 2021) as well as in maps of Balmer (e.g. Hα, Hβ, see Livermore et al 2012;Mieda et al 2016;Fisher et al 2017;Zanella et al 2019;Whitmore et al 2020) and Paschen (e.g.…”

Exploration of the high-redshift universe enabled by THESEUS

“…[62]). Studies, which take advantage of gravitational lensing by galaxy clusters in the Hubble Frontier Fields, can reach even fainter magnitudes, albeit probing increasingly smaller volumes in the higher magnification regime, and are also consistent with a steep faint-end slope [69][70][71]. The value of the total luminosity integral depends sensitively on the choice of low-luminosity cut-off (and indeed the assumption of continued power-law form for the LF).…”

High-redshift Lyman-alpha emitters in blank and lensing fields

“…For more details on the data 3.3. MUSE LYα SPECTRAL ANALYSIS reduction and source detection other than Lyα of these clusters, please refer to Caminha et al (2017bCaminha et al ( , 2019; Bergamini et al (2021); Chen et al (2021) and Vanzella et al (2021).…”

“…We make the redshift catalog with these new sources available with this publication. For the lensing cluster pointings, we made use of the publicly available catalogs presented in Caminha et al (2017bCaminha et al ( , 2019 and Vanzella et al (2021). After we identified the Lyα emission sample, we extracted our spectra again by defining an area where the line emission was at least 3σ above the surrounding noise level.…”

“…Studies of lensed Lyα emitters have already yielded results on the luminosity distribution and the expected number density of these sources Richard et al 2021), but a detailed statistical study of their emission profile shape has yet to be done. For this study we combine four CLASH-VLT (Postman et al 2012;Rosati et al 2014) lensing clusters: MACS J0329, J0416, J1206, and J1931 (Caminha et al 2017b(Caminha et al , 2019Bergamini et al 2021;Chen et al 2021;Vanzella et al 2021) with a MUSE pointing in the COSMOS field (Scoville et al 2007) to gain access to a broader range of galaxy luminosities.…”