%0 Generic %1 vanzella2016paving %A Vanzella, E. %A Calura, F. %A Meneghetti, M. %A Mercurio, A. %A Castellano, M. %A Caminha, G. B. %A Balestra, I. %A Rosati, P. %A Tozzi, P. %A De Barros, S. %A Grazian, A. %A D'Ercole, A. %A Ciotti, L. %A Caputi, K. %A Grillo, C. %A Merlin, E. %A Pentericci, L. %A Fontana, A. %A Cristiani, S. %A Coe, D. %D 2016 %K cluster formation globular %T Paving the way for the JWST: witnessing globular cluster formation at z>3 %U http://arxiv.org/abs/1612.01526 %X We report of five compact, extremely young (<10Myr) and blue (\beta<-2.5, Fłambda=łambda^\beta) objects observed with VLT/MUSE at z=3.1169, 3.235, plus three additional objects at z=6.145. These sources are magnified by the Hubble Frontier Field galaxy clusters MACS~J0416 and AS1063. Their intrinsic half light radii (Re) are in the range between 14 to 140pc. We estimate de-lensed stellar masses ~1-20x10^6 Msun and magnitudes m_UV=28.8-31.4 (i.e., -17<M_UV<-15). Multiple images of these systems are widely separated in the sky (up to 50 arcsec) and individually magnified by factors 3-40. Remarkably, the inferred physical properties of two objects are similar to those expected in some globular cluster formation scenarios, representing the best candidate proto-globular clusters (proto-GC) discovered so far. Interestingly, one of them at z=3.1169, with de-lensed Re~43pc and available rest-frame optical spectroscopy, shows a velocity dispersion \sigma_v~20 km\s, implying a dynamical mass dominated by the stellar mass. Another object at z=6.145, with de-lensed M_UV ~ -15.3 (m_UV~31.4), shows a stellar mass and a star-formation rate surface density compatible with the values expected in the most popular GC formation scenarios. An additional star-forming region at z=6.145, with de-lensed m_UV~32 and stellar mass and star formation rate estimates of 0.5 x 10^6 Musn and 0.06 Msun/yr, is also identified. These objects currently represent the faintest spectroscopically confirmed star-forming systems at z>3, elusive even in the deepest blank fields. We consider the possibility that proto-GCs might contribute to the ionization budget of the universe and augment the Lya visibility during reionization. This work underlines the crucial role of JWST in characterizing the rest-frame optical and near-infrared properties of such low-luminosity high-z objects.

@misc{vanzella2016paving, abstract = {We report of five compact, extremely young (<10Myr) and blue (\beta<-2.5, F\lambda=\lambda^\beta) objects observed with VLT/MUSE at z=3.1169, 3.235, plus three additional objects at z=6.145. These sources are magnified by the Hubble Frontier Field galaxy clusters MACS~J0416 and AS1063. Their intrinsic half light radii (Re) are in the range between 14 to 140pc. We estimate de-lensed stellar masses ~1-20x10^6 Msun and magnitudes m_UV=28.8-31.4 (i.e., -17<M_UV<-15). Multiple images of these systems are widely separated in the sky (up to 50 arcsec) and individually magnified by factors 3-40. Remarkably, the inferred physical properties of two objects are similar to those expected in some globular cluster formation scenarios, representing the best candidate proto-globular clusters (proto-GC) discovered so far. Interestingly, one of them at z=3.1169, with de-lensed Re~43pc and available rest-frame optical spectroscopy, shows a velocity dispersion \sigma_v~20 km\s, implying a dynamical mass dominated by the stellar mass. Another object at z=6.145, with de-lensed M_UV ~ -15.3 (m_UV~31.4), shows a stellar mass and a star-formation rate surface density compatible with the values expected in the most popular GC formation scenarios. An additional star-forming region at z=6.145, with de-lensed m_UV~32 and stellar mass and star formation rate estimates of 0.5 x 10^6 Musn and 0.06 Msun/yr, is also identified. These objects currently represent the faintest spectroscopically confirmed star-forming systems at z>3, elusive even in the deepest blank fields. We consider the possibility that proto-GCs might contribute to the ionization budget of the universe and augment the Lya visibility during reionization. This work underlines the crucial role of JWST in characterizing the rest-frame optical and near-infrared properties of such low-luminosity high-z objects.}, added-at = {2016-12-07T09:36:00.000+0100}, author = {Vanzella, E. and Calura, F. and Meneghetti, M. and Mercurio, A. and Castellano, M. and Caminha, G. B. and Balestra, I. and Rosati, P. and Tozzi, P. and De Barros, S. and Grazian, A. and D'Ercole, A. and Ciotti, L. and Caputi, K. and Grillo, C. and Merlin, E. and Pentericci, L. and Fontana, A. and Cristiani, S. and Coe, D.}, biburl = {https://www.bibsonomy.org/bibtex/22360c182656217211d5c9ddf84871fd1/miki}, description = {[1612.01526] Paving the way for the JWST: witnessing globular cluster formation at z&gt;3}, interhash = {dd9918f92c07f906a488fac011bee8dd}, intrahash = {2360c182656217211d5c9ddf84871fd1}, keywords = {cluster formation globular}, note = {cite arxiv:1612.01526Comment: 19 pages, 9 figures, 2 tables. Submitted to MNRAS. Comments welcome}, timestamp = {2016-12-07T09:36:00.000+0100}, title = {Paving the way for the JWST: witnessing globular cluster formation at z>3}, url = {http://arxiv.org/abs/1612.01526}, year = 2016 }