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Probing feedback and evolution using Lya halos around extremely red quasars

Presentation #529.05 in the session “Quasars”.

Published onJan 11, 2021
Probing feedback and evolution using Lya halos around extremely red quasars

Dust obscured quasars are believed to be in a young stage of quasar/galaxy evolution, when quasar feedback could be more important for driving blowouts and disrupting star formation in their host galaxies. Our team discovered a remarkable population of luminous extremely red quasars (ERQs), at redshifts z ~ 2-4 in BOSS and WISE surveys. ERQs are defined by extremely red colors across rest UV to mid-IR. They have a suite of extreme spectral properties that may all be related to exceptionally powerful quasar driven outflows. We present analysis of their extended Lya emitting halos. Dust obscuration acts as a natural coronagraph, allowing views of the innermost halo regions. Remarkably, the extended Lya halos are kinematically quiet despite the extreme outflows observed in the quasar spectra. Comparing with normal blue quasars reveals only marginal differences in the sizes and morphologies of the Lya halos. We will discuss implications of these findings for feedback and evolution. Further, our results imply that for studies of large line blueshifts in quasar spectra, the halo redshifts are good indicators of the systemic redshifts. Finally for a broader undestanding of the role of active galactic nuclei in galaxy evolution, optically fainter and even redder active galactic nuclei should be surveyed and characterized.

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