Introducing extremely red quasars. Models predict that massive black holes mostly grow in obscurity inside a dusty starburst until a blowout of gas and dust quenches star formation and reveal a visibly luminous quasar. Dust-reddened quasars are believed to be in the transition phase and still partially embedded. At the peak epoch of galaxy formation and quasar activity, feedback should have the greatest impact. We discovered a remarkable population of “extremely red quasars” at z ~ 2–3 in the Baryon Oscillation Sky Survey (Hamann+17). ERQs have extremely red colors from rest-frame UV to mid-IR, high bolometric luminosities, and normal radio emission. They have exceptionally broad and blueshifted [OIII]5007 reaching speeds >6000 km s−1 (Perrotta+19). [OIII]5007 emissions in ERQs are compact. We obtained adaptive-optics integral-ﬁeld spectra of 10 ERQs (Vayner+21; Lau+23). We identify physically distinct [OIII] kinematic components that are bimodal, and respectively trace ERQ-driven outﬂows and dynamically quiescent interstellar media. The outﬂows are ~1 kpc scales whereas the quiescent gas extends to few kpc. Compared to normal quasars the extremely fast ERQ-driven outﬂows are compact, supporting that ERQs are in a young evolution stage and represent unique physical conditions beyond orientation diﬀerences. The kinematically quiescent emissions are spatially- resolved but less extended than normal quasars, which can be explained by patchy obscuration. The hint of ionization cones suggests patchy torus. A deep survey for even redder, fainter ERQs. The extreme outﬂow properties are tied to their extreme red i−W3 (or z−W3) colors. We are searching for ERQs that are even redder to explore the possibility of more extreme physical properties tied perhaps to an even earlier evolution stage. We select candidates from DESI+WISE photometry based on the unique spectral energy distribution that is ﬂat across rest-frame UV, and conﬁrm with optical spectroscopy. If you study red quasars, I invite you to compare our selection techniques and the characteristic properties. Probing Quasar-Galaxy Evolution via Extremely Red Quasars / Probing Inﬂows onto Quasar Hosts via Associated Absorbers Marie Wingyee Lau (wingyeel@ucr.edu; University of California, Riverside), Fred Hamann 16000 16200 16400 16600 0 20 40 60 80 100 Average SB (10−17 cgs arcsec−2) 0.0" ≤ distance < 0.1" Data Fits 16000 16200 16400 16600 0 5 10 15 Average SB (10−17 cgs arcsec−2) 0.1" ≤ distance < 0.2" Data Fits 16000 16200 16400 16600 0 1 2 3 4 5 Average SB (10−17 cgs arcsec−2) 0.2" ≤ distance < 0.4" Data Fits 16000 16200 16400 16600 0.0 0.5 1.0 1.5 2.0 Average SB (10−17 cgs arcsec−2) 0.4" ≤ distance < 0.6" Data Fits Wavelength (Å) 16000 16200 16400 16600 0.0 0.5 1.0 1.5 2.0 Average SB (10−17 cgs arcsec−2) 0.6" ≤ distance < 1.0" Data Fits Wavelength (Å) Wavelength (Å) 16000 16200 16400 16600 0.0 0.5 1.0 1.5 2.0 Average SB (10−17 cgs arcsec−2) 1.0" ≤ distance < 1.4" Data Fits Wavelength (Å) Wavelength (Å) Wavelength (Å) −1 0 1 −1 0 1 (arcsec) (arcsec) 0.0 0.2 0.4 0.6 0.8 1.0 SB (10−14 cgs arcsec−2) J0006+1215 Hn3 Residual Relative Velocity (km s−1) Relative Velocity (km s−1) SiIV at z = 1.716 −400 −200 0 +200 +400 −2600 −2400 −2200 −2000 CIV 1548 CIV 1548 CIV 1550 CIV 1550 NV 1238 NV 1238 NV 1242 NV 1242 SiIV 1393 SiIV 1393 SiIV 1402 SiIV 1402 SiIII 1206 SiIII 1206 HI 1215 HI 1215 Left: Spectra extracted from nuclear and annular apertures of the reddest ERQ J0006+1215, and the best fits. We overplot the individual continuum, Hβ, broad and narrow [OIII] components. Right: Residual surface brightness map of J0006+1215 after subtracting the point spread function. The residuals are dominated by the narrow [OIII] component. Right: AB color vs. observed wavelength for candidates compared to median SED of known ERQs, Type 1 QSO with and without reddening, hot DOGs, highly reddened Type 1, Type 2 QSO, and starburst galaxy NGC 6240. Left: A newly-discovered ERQ. We see the characteristic s