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The X-ray and radio activity of typical and luminous Ly α emitters from z ∼ 2 to z ∼ 6: evidence for a diverse, evolving population

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  • Despite recent progress in understanding Ly a emitters (LAEs), relatively little is known regarding their typical black hole activity across cosmic time. Here, we study the X-ray and radio properties of ~4000 LAEs at 2.2 3) with an average luminosity of 10^{44.31± 0.01} erg s^{-1} and average black hole accretion rate (BHAR) of 0.72 ± 0.01 M? yr-1, consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of 3.2{{ per cent}} ± 0.3{{ per cent}}). The global AGN fraction (8.6{{ per cent}} ± 0.4{{ per cent}}) rises with Ly a luminosity and declines with increasing redshift. For X -ray-detected LAEs, Ly a luminosities correlate with the BHARs, suggesting that Ly a luminosity becomes a BHAR indicator. Most LAEs (93.1{{ per cent}} ± 0.6{{ per cent}}) at 2 , consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of 3.2{{ per cent}} ± 0.3{{ per cent}}). The global AGN fraction (8.6{{ per cent}} ± 0.4{{ per cent}}) rises with Ly a luminosity and declines with increasing redshift. For X -ray-detected LAEs, Ly a luminosities correlate with the BHARs, suggesting that Ly a luminosity becomes a BHAR indicator. Most LAEs (93.1{{ per cent}} ± 0.6{{ per cent}}) at 2 , consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of 3.2{{ per cent}} ± 0.3{{ per cent}}). The global AGN fraction (8.6{{ per cent}} ± 0.4{{ per cent}}) rises with Ly a luminosity and declines with increasing redshift. For X -ray-detected LAEs, Ly a luminosities correlate with the BHARs, suggesting that Ly a luminosity becomes a BHAR indicator. Most LAEs (93.1{{ per cent}} ± 0.6{{ per cent}}) at 2 , consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of 3.2{{ per cent}} ± 0.3{{ per cent}}). The global AGN fraction (8.6{{ per cent}} ± 0.4{{ per cent}}) rises with Ly a luminosity and declines with increasing redshift. For X -ray-detected LAEs, Ly a luminosities correlate with the BHARs, suggesting that Ly a luminosity becomes a BHAR indicator. Most LAEs (93.1{{ per cent}} ± 0.6{{ per cent}}) at 2 ? yr-1). The median star formation rate (SFR) of star-forming LAEs from Ly a and radio luminosities is 7.6^{+6.6}_{-2.8} M? yr-1. The black hole to galaxy growth ratio (BHAR/SFR) for LAEs is %26lt;0.0022, consistent with typical star-forming galaxies and the local BHAR/SFR relation. We conclude that LAEs at 2 %26lt; z %26lt; 6 include two different populations: an AGN population, where Ly a luminosity traces BHAR, and another with low SFRs which remain undetected in even the deepest X-ray stacks but is detected in the radio stacks.
  • Despite recent progress in understanding Ly α emitters (LAEs), relatively little is known regarding their typical black hole activity across cosmic time. Here, we study the X-ray and radio properties of ∼4000 LAEs at 2.2 3) with an average luminosity of 10^{44.31± 0.01} erg s^{-1} and average black hole accretion rate (BHAR) of 0.72 ± 0.01 M yr-1, consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of 3.2{{ per cent}} ± 0.3{{ per cent}}). The global AGN fraction (8.6{{ per cent}} ± 0.4{{ per cent}}) rises with Ly α luminosity and declines with increasing redshift. For X -ray-detected LAEs, Ly α luminosities correlate with the BHARs, suggesting that Ly α luminosity becomes a BHAR indicator. Most LAEs (93.1{{ per cent}} ± 0.6{{ per cent}}) at 2 , consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of 3.2{{ per cent}} ± 0.3{{ per cent}}). The global AGN fraction (8.6{{ per cent}} ± 0.4{{ per cent}}) rises with Ly α luminosity and declines with increasing redshift. For X -ray-detected LAEs, Ly α luminosities correlate with the BHARs, suggesting that Ly α luminosity becomes a BHAR indicator. Most LAEs (93.1{{ per cent}} ± 0.6{{ per cent}}) at 2 , consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of 3.2{{ per cent}} ± 0.3{{ per cent}}). The global AGN fraction (8.6{{ per cent}} ± 0.4{{ per cent}}) rises with Ly α luminosity and declines with increasing redshift. For X -ray-detected LAEs, Ly α luminosities correlate with the BHARs, suggesting that Ly α luminosity becomes a BHAR indicator. Most LAEs (93.1{{ per cent}} ± 0.6{{ per cent}}) at 2 , consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of 3.2{{ per cent}} ± 0.3{{ per cent}}). The global AGN fraction (8.6{{ per cent}} ± 0.4{{ per cent}}) rises with Ly α luminosity and declines with increasing redshift. For X -ray-detected LAEs, Ly α luminosities correlate with the BHARs, suggesting that Ly α luminosity becomes a BHAR indicator. Most LAEs (93.1{{ per cent}} ± 0.6{{ per cent}}) at 2 yr-1). The median star formation rate (SFR) of star-forming LAEs from Ly α and radio luminosities is 7.6^{ 6.6}_{-2.8} M yr-1. The black hole to galaxy growth ratio (BHAR/SFR) for LAEs is <0.0022, consistent with typical star-forming galaxies and the local BHAR/SFR relation. We conclude that LAEs at 2 < z < 6 include two different populations: an AGN population, where Ly α luminosity traces BHAR, and another with low SFRs which remain undetected in even the deepest X-ray stacks but is detected in the radio stacks.

Publication Date

  • 2020