TY - JOUR
T1 - Evidence for Cold-stream to Hot-accretion Transition as Traced by Ly α Emission from Groups and Clusters at 2 < z < 3.3
AU - Daddi, E.
AU - Rich, R. M.
AU - Valentino, F.
AU - Jin, S.
AU - Delvecchio, I.
AU - Liu, D.
AU - Strazzullo, V.
AU - Neill, J.
AU - Gobat, R.
AU - Finoguenov, A.
AU - Bournaud, F.
AU - Elbaz, D.
AU - Kalita, B. S.
AU - O'Sullivan, D.
AU - Wang, T.
N1 - Funding Information:
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.
Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
PY - 2022/2/1
Y1 - 2022/2/1
N2 - We present Keck Cosmic Web Imager observations of giant Lyα halos surrounding nine galaxy groups and clusters at 2 < z < 3.3, including five new detections and one upper limit. We find observational evidence for the cold-stream to hot-accretion transition predicted by theory by measuring a decrease in the ratio between the spatially extended Lyα 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 = 1040.51±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.
AB - We present Keck Cosmic Web Imager observations of giant Lyα halos surrounding nine galaxy groups and clusters at 2 < z < 3.3, including five new detections and one upper limit. We find observational evidence for the cold-stream to hot-accretion transition predicted by theory by measuring a decrease in the ratio between the spatially extended Lyα 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 = 1040.51±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.
UR - http://www.scopus.com/inward/record.url?scp=85125732660&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/ac531f
DO - 10.3847/2041-8213/ac531f
M3 - Article
AN - SCOPUS:85125732660
SN - 2041-8205
VL - 926
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L21
ER -