%0 Generic %1 vanzella2017magnifying %A Vanzella, E. %A Castellano, M. %A Meneghetti, M. %A Mercurio, A. %A Caminha, G. B. %A Cupani, G. %A Calura, F. %A Christensen, L. %A Merlin, E. %A Rosati, P. %A Gronke, M. %A Dijkstra, M. %A Mignoli, M. %A Gilli, R. %A De Barros, S. %A Caputi, K. %A Grillo, C. %A Balestra, I. %A Cristiani, S. %A Nonino, M. %A Giallongo, E. %A Grazian, A. %A Pentericci, L. %A Fontana, A. %A Comastri, A. %A Vignali, C. %A Zamorani, G. %A Brusa, M. %A Bergamini, P. %A Tozzi, P. %D 2017 %K Lya clumps emission metal %T Magnifying the early episodes of star formation: super-star clusters at cosmological distances %U http://arxiv.org/abs/1703.02044 %X We present VLT/MUSE and VLT/X-Shooter spectra of two faint (m_uv ~ 30.6), young (< 100 Myr), low-mass (<10^(7) Msun), low-metallicity (12+Log(O/H)~7.7, or 1/10 solar) and compact (30 pc effective radius) stellar systems separated by ~300 pc at z=3.2222, after correcting from the strong lensing effect. Six multiple images have been identified in the Hubble Frontier Field images of the galaxy cluster MACS-J0416, with magnifications \mu~40-70 for the brightest ones. We measured CIV1548-1550, HeII1640, OIII1661-1666, CIII1907-1909, Hbeta and OIII4959-5007 emission lines with velocity dispersion \sigma_v < 25 km/s measured with X-Shooter and (de-lensed) line fluxes as faint as 10^(-19) erg/s/cm2. This suggests hot stars are present in star-clusters whose mass is dominated by the stellar mass. Remarkably, the ultraviolet metal lines are not accompanied by Lya emission (e.g., CIV / Lya > 12), despite the Lya line flux is expected to be 150 times brighter (inferred from the Hbeta flux) arising in a mostly photo-ionized medium (OIII5007 / OII3727 >10). The detection at the same redshift of a spatially-offset and strongly-magnified (>50) Lya emission at ~2 kpc, with a de-lensed spatial extension < 7.6 kpc^2, suggests a transverse leakage of ionizing radiation from the star-clusters that induces Lya fluorescence. The offset emission could also originate from another extremely faint source with m_uv >34 (de-lensed) and EW(Lya) > 450\AA\ rest-frame. This is the first confirmed metal-line emitter at such low-luminosity and redshift without Lya emission, suggesting that a highly fluctuating Lya visibility might be in place also in these regimes and small sizes.

@misc{vanzella2017magnifying, abstract = {We present VLT/MUSE and VLT/X-Shooter spectra of two faint (m_uv ~ 30.6), young (< 100 Myr), low-mass (<10^(7) Msun), low-metallicity (12+Log(O/H)~7.7, or 1/10 solar) and compact (30 pc effective radius) stellar systems separated by ~300 pc at z=3.2222, after correcting from the strong lensing effect. Six multiple images have been identified in the Hubble Frontier Field images of the galaxy cluster MACS-J0416, with magnifications \mu~40-70 for the brightest ones. We measured CIV1548-1550, HeII1640, OIII]1661-1666, CIII]1907-1909, Hbeta and [OIII]4959-5007 emission lines with velocity dispersion \sigma_v < 25 km/s measured with X-Shooter and (de-lensed) line fluxes as faint as 10^(-19) erg/s/cm2. This suggests hot stars are present in star-clusters whose mass is dominated by the stellar mass. Remarkably, the ultraviolet metal lines are not accompanied by Lya emission (e.g., CIV / Lya > 12), despite the Lya line flux is expected to be 150 times brighter (inferred from the Hbeta flux) arising in a mostly photo-ionized medium ([OIII]5007 / [OII]3727 >10). The detection at the same redshift of a spatially-offset and strongly-magnified (\mu >50) Lya emission at ~2 kpc, with a de-lensed spatial extension < 7.6 kpc^2, suggests a transverse leakage of ionizing radiation from the star-clusters that induces Lya fluorescence. The offset emission could also originate from another extremely faint source with m_uv >34 (de-lensed) and EW(Lya) > 450\AA\ rest-frame. This is the first confirmed metal-line emitter at such low-luminosity and redshift without Lya emission, suggesting that a highly fluctuating Lya visibility might be in place also in these regimes and small sizes.}, added-at = {2017-03-08T19:00:23.000+0100}, author = {Vanzella, E. and Castellano, M. and Meneghetti, M. and Mercurio, A. and Caminha, G. B. and Cupani, G. and Calura, F. and Christensen, L. and Merlin, E. and Rosati, P. and Gronke, M. and Dijkstra, M. and Mignoli, M. and Gilli, R. and De Barros, S. and Caputi, K. and Grillo, C. and Balestra, I. and Cristiani, S. and Nonino, M. and Giallongo, E. and Grazian, A. and Pentericci, L. and Fontana, A. and Comastri, A. and Vignali, C. and Zamorani, G. and Brusa, M. and Bergamini, P. and Tozzi, P.}, biburl = {https://www.bibsonomy.org/bibtex/20f133d3a957345cbb23fa12af399a2dc/miki}, description = {[1703.02044] Magnifying the early episodes of star formation: super-star clusters at cosmological distances}, interhash = {705d3f2d332b9f6af49d2733e46e4dd1}, intrahash = {0f133d3a957345cbb23fa12af399a2dc}, keywords = {Lya clumps emission metal}, note = {cite arxiv:1703.02044Comment: 7 pages, 4 figures. Submitted to ApJL. Comments welcome}, timestamp = {2017-03-08T19:00:23.000+0100}, title = {Magnifying the early episodes of star formation: super-star clusters at cosmological distances}, url = {http://arxiv.org/abs/1703.02044}, year = 2017 }