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Evidence for Cold-stream to Hot-accretion Transition as Traced by Lyα Emission from Groups and Clusters at 2 < z < 3.3

Daddi, E. and Rich, R. Michael and Valentino, F. and Jin, S. and Delvecchio, I. and Liu, D. and Strazzullo, V. and Neill, J. and Gobat, R. and Finoguenov, A. and Bournaud, F. and Elbaz, D. and Kalita, B. S. and O’Sullivan, D. and Wang, T. (2022) Evidence for Cold-stream to Hot-accretion Transition as Traced by Lyα Emission from Groups and Clusters at 2 < z < 3.3. Astrophysical Journal Letters, 926 (2). Art. No. L21. ISSN 2041-8205. doi:10.3847/2041-8213/ac531f.

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We present Keck Cosmic Web Imager observations of giant Lyα halos surrounding nine galaxy groups and clusters at 2 < z < α luminosity and the expected baryonic accretion rate (BAR), with increasing elongation above the transition mass (M_(stream)). This implies a modulation of the share of BAR that remains cold, diminishing quasi-linearly (logarithmic slope of 0.97 ± 0.19, 5σ significance) with the halo to M_(stream) mass ratio. The integrated star formation rates (SFRs) and active galactic nucleus (AGN) bolometric luminosities display a potentially consistent decrease, albeit significant only at 2.6σ and 1.3σ, respectively. The higher scatter in these tracers suggests the Lyα emission might be mostly a direct product of cold accretion in these structures rather than indirect, mediated by outflows and photoionization from SFR and AGNs; this is also supported by energetics considerations. Below M_(stream) (cold-stream regime), we measure L_(Lyα)/BAR = 10^(40.51 ± 0.16) erg s⁻1 M_⊙⁻¹ yr, consistent with predictions, and SFR/BAR = 10^(−0.54 ± 0.23): on average, 30₋₁₀⁺²⁰% of the cold streams go into stars. Above M_(stream) (hot-accretion regime), L_(Lyα) is set by M_(stream) (within 0.2 dex scatter in our sample), independent of the halo mass but rising 10-fold from z = 2 to 3.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Daddi, E.0000-0002-3331-9590
Rich, R. Michael0000-0003-0427-8387
Valentino, F.0000-0001-6477-4011
Jin, S.0000-0002-8412-7951
Delvecchio, I.0000-0001-8706-2252
Liu, D.0000-0001-9773-7479
Strazzullo, V.0000-0001-7975-2894
Neill, J.0000-0002-0466-1119
Finoguenov, A.0000-0002-4606-5403
Bournaud, F.0000-0002-5743-0250
Elbaz, D.0000-0002-7631-647X
Kalita, B. S.0000-0001-9215-7053
Wang, T.0000-0002-2504-2421
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 November 23; revised 2022 February 5; accepted 2022 February 7; published 2022 February 21. We thank Dawn Erb for sharing calibrations, Sebastiano Cantalupo for his CubEx code and discussions, and the referee for a constructive report. R.M.R. acknowledges GO-15910.002 from the Space Telescope Science Institute. Data were obtained at the W. M. Keck Observatory, operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, made possible by the generous financial support of the W. M. Keck Foundation. The authors also acknowledge the indigenous Hawaiian community and are grateful for the opportunity to collect data from the summit of Maunakea.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Galaxy evolution; Galaxy accretion
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Galaxy evolution (594); Galaxy accretion (575)
Record Number:CaltechAUTHORS:20220222-706730000
Persistent URL:
Official Citation:E. Daddi et al 2022 ApJL 926 L21
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113530
Deposited By: George Porter
Deposited On:23 Feb 2022 02:29
Last Modified:25 Jul 2022 23:14

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