4.7 Article

SHOCKED SUPERWINDS FROM THE z ∼ 2 CLUMPY STAR-FORMING GALAXY, ZC406690

期刊

ASTROPHYSICAL JOURNAL
卷 752, 期 2, 页码 -

出版社

IOP Publishing Ltd
DOI: 10.1088/0004-637X/752/2/111

关键词

galaxies: evolution; galaxies: high-redshift; galaxies: star formation; ISM: jets and outflows

资金

  1. NSF
  2. ASI
  3. INAF

向作者/读者索取更多资源

We have obtained high-resolution data of the z similar to 2 ring-like, clumpy star-forming galaxy (SFG) ZC406690 using the VLT/SINFONI with adaptive optics (in K band) and in seeing-limited mode (in H and J bands). Our data include all of the main strong optical emission lines: [O II], [O III], H alpha, H beta, [N II], and [S II]. We find broad, blueshifted H alpha and [O III] emission line wings in the spectra of the galaxy's massive, star-forming clumps (sigma similar to 85 km s(-1)) and even broader wings (up to 70% of the total Ha flux, with s similar to 290 km s(-1)) in regions spatially offset from the clumps by similar to 2 kpc. The broad emission likely originates from large-scale outflows with mass outflow rates from individual clumps that are 1-8x the star formation rate (SFR) of the clumps. Based on emission line ratio diagnostics ([N II]/H alpha and [S II]/H alpha) and photoionization and shock models, we find that the emission from the clumps is due to a combination of photoionization from the star-forming regions and shocks generated in the outflowing component, with 5%-30% of the emission deriving from shocks. In terms of the ionization parameter (6x10(7) to 10(8) cm s(-1), based on both the SFR and the O-32 ratio), density (local electron densities of 300-1800 cm(-3) in and around the clumps, and ionized gas column densities of 1200-8000 M(circle dot)pc(-2)), and SFR (10-40 M-circle dot yr(-1)), these clumps more closely resemble nuclear starburst regions of local ultraluminous infrared galaxies and dwarf irregulars than H II regions in local galaxies. However, the star-forming clumps are not located in the nucleus as in local starburst galaxies but instead are situated in a ring several kpc from the center of their high-redshift host galaxy, and have an overall disk-like morphology. The two brightest clumps are quite different in terms of their internal properties, energetics, and relative ages, and thus we are given a glimpse at two different stages in the formation and evolution of rapidly star-forming giant clumps at high-z.

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