S319p.115 — High-Redshift Protoclusters Traced by Submillimeter Galaxies

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Aug 10th at 6:00 PM until 6:00 PM




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Author(s): Karín Menéndez-Delmestre4, Andrew Blain3, Peter Capak1, Kartik Sheth2, Aldée Charbonnier4, Thiago Signorini Gonçalves4

Institution(s): 1. California Institute of Technology, 2. National Radio Astronomy Observatory, 3. University of Leicester, 4. Valongo Observatory, Universidade Federal do Rio de Janeiro

Galaxy evolution is intimately connected to the environment. To understand the origin of the galaxy-environment relation, one needs to look back at the epoch of galaxy formation (z > 1), where the local high-density environments of well-established, virialized clusters give way to looser large-scale structures (LSS) extending over regions of several megaparsecs in size (protoclusters). Different tracers have been used to map z>2 LSS; in particular, powerful radio galaxies. Considering that these objects are only visible for a short period in the evolution of a massive galaxy, there is a significant fraction of forming clusters that remain unexplored. To identify the typical overdense regions at z>2 we need tracers that are more abundant than these extreme objects. Clustering analysis indicate that at z~2 submm-selected galaxies (SMGs) reside in very massive halos, suggesting that these may trace high-density environments that likely evolve into rich clusters of galaxies. Conversely, recent work suggests that SMGs are tracers of a broader range of environments, including structures with more modest masses caught in highly active periods. This suggests that since galaxies in these structures are likely caught during episodes of peak starbursts, SMGs may be tracers of a wider range of environments beyond the progenitors of today’s very rich clusters, opening a window for a more complete exploration of the details underpinning the process of galaxy evolution in concert with the assembly of LSS. We have undertaken a large observing program comprising deep narrow-band Ly-alpha imaging and multi-object spectroscopy using Palomar/Keck/Magellan/Gemini telescopes to probe for galaxy overdensities in SMG environments at z~1-5. With >200 spectroscopically-confirmed Ly-alpha emitters, we are in a position to gauge the level of galaxy overdensity in these regions. Furthermore, we have initiated a detailed study of the distribution in galaxy properties according to the maturity and evolving stage of LSS traced by SMGs, in an effort to explore the way galaxy and local environment relate to each other within the broader picture of a cosmologically-evolving LSS.