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|Title:||Massive star cluster formation under the microscope at z = 6||Authors:||VANZELLA, Eros
Caminha, G. B.
|Issue Date:||2019||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||483||Issue:||3||First Page:||3618||Abstract:||We report on a superdense star-forming region with an effective radius (R<SUB>e</SUB>) smaller than 13 pc identified at z = 6.143 and showing a star formation rate density Σ<SUB>SFR</SUB> ∼ 1000 M<SUB>⊙</SUB> yr<SUP>-1</SUP> kpc<SUP>-2</SUP> (or conservatively >300 M<SUB>⊙</SUB> yr<SUP>-1</SUP> kpc<SUP>-2</SUP>). Such a dense region is detected with S/N ≳ 40 hosted by a dwarf extending over 440 pc, dubbed D1. D1 is magnified by a factor 17.4(±5.0) behind the Hubble Frontier Field galaxy cluster MACS J0416 and elongated tangentially by a factor 13.2 ± 4.0 (including the systematic errors). The lens model accurately reproduces the positions of the confirmed multiple images with a rms of 0.35 arcsec. D1 is part of an interacting star-forming complex extending over 800 pc. The SED-fitting, the very blue ultraviolet slope (β ≃ -2.5, F<SUB>λ</SUB> ∼ λ<SUP>β</SUP>), and the prominent Lyα emission of the stellar complex imply that very young (<10-100 Myr), moderately dust-attenuated (E(B - V) < 0.15) stellar populations are present and organized in dense subcomponents. We argue that D1 (with a stellar mass of 2 × 10<SUP>7</SUP> M<SUB>⊙</SUB>) might contain a young massive star cluster of M ≲ 10<SUP>6</SUP> M<SUB>⊙</SUB> and M<SUB>UV</SUB> ≃ -15.6 (or m<SUB>UV</SUB> = 31.1), confined within a region of 13 pc, and not dissimilar from some local super star clusters (SSCs). The ultraviolet appearance of D1 is also consistent with a simulated local dwarf hosting an SSC placed at z = 6 and lensed back to the observer. This compact system fits into some popular globular cluster formation scenarios. We show that future high spatial resolution imaging (e.g. E-ELT/MAORY-MICADO and VLT/MAVIS) will allow us to spatially resolve light profiles of 2-8 pc.||URI:||http://hdl.handle.net/20.500.12386/30776||URL:||http://arxiv.org/abs/1809.02617v2
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Jun 15, 2021
checked on Jun 15, 2021
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