Low-redshift Lyman-α Blobs Low-redshift Lyman-α Blobs Mischa Schirmer Gemini Observatory, Chile Collaborators: K. Ichikawa (NAOJ) T. Kawamuro (U Kyoto) S. Malhotra (Arizona State U) N. Levenson (Gemini South) H. Fu (U Iowa) R.E. Davies (MPE) C. Ricci (PUC) W. Keel (U Alabama) P. Torrey (CfA / MIT) J. Turner (Gemini South) Schirmer+ 2016, MNRAS, 463, 1554

Outline: LABs rapidly disappear with cosmic time LABs rapidly disappear with cosmic time Ideal to study the Lyα escape mechanism Ideal to study the Lyα escape mechanism Why so few AGN in LABs Why so few AGN in LABs

LAB Fact Sheet: Luminous clouds of ionized gas Nilsson (z=3.16) Matsuda (z=3.1) Luminosities: Lyα ~ – 44 erg s –1 Size: 20 – 150 kpc Mostly at z = 2 – 3 Landmarks of massive galaxy formation Barger (z=0.97) Selecting Lyα using narrow-band imaging FAINT!! (hours of exposure time)

Result #1: LABs still exist at low redshift! Prediction by Overzier+ 2013: LABs should still exist at low redshift: In the field (clusters too hot for cold accretion) Powered by AGN (cold accretion depletes) Rare Main result #1: YES, they do exist! Live in the field. Powered by AGN. Extremely rare. LABs are abundant in dense proto-clusters at z ~ 2. Keel+ (2009): GALEX search in cluster field at z ~ 0.8: Expected 30: Found 0

Low-z LABs (z ~ 0.3; r ~ 18 mag) Gemini GMOS gri-band images [OIII], Lyα: – 44 erg s –1 Size: 20 – 80 kpc GALEX FUV: Lyα bright! Amongst most [OIII]-luminous objects known 1 in 1000 deg 2

Project #1: How quickly do LABs go extinct? Density ~ (1+z) AGN model predictions ~1200 candidates from PanSTARRS (Dec 2016) + Gemini spec-z (poor weather program) + GALEX FUV / NUV cross-match

Project #2: Studying the Lyα escape mechanism Resonant scattering

Project #2: Studying the Lyα escape mechanism Lyα escape depends on: – Dust – Metallicity – Outflows – Neutral hydrogen Lyα is key observable: – evolution of high-z galaxies – reionization of the Universe Exploit high fluxes of 3 low-z LABs! Pilot study, resolving kpc scales, involving – Gemini: GMOS 3D spectra – Chandra + NuSTAR: soft+hard X-rays – HST: direct Lyα imaging and spectra

Francis (z=2.38) We don't see them in X-rays→ “They must be heavily obscured” “[...] requires particular combinations of geometric and radiative transfer effects to explain escape of Lyα while simultaneously maintaining obscuration along the line of sight.” (Steidel+ 2000) Result #2: Why so few AGN in LABs? LABs → massive galaxy formation → growth of central black holes / AGN → Transient AGN Rapid duty cycles (10 4–5 years) (e.g. Schawinski+ 2015) AGN: 0.1 – 1% of time in quasar mode (Hopkins+2010; Novak+ 2011; Sijacki+ 2015)

Result #2: Why so few AGN in LABs? – Transient AGN!

Main result #2: We do NOT expect to find luminous AGN in luminous LABs! Time of X-ray observation Result #2: Why so few AGN in LABs? – Transient AGN!

Summary We found low-z LABs exist 4–7 billion years later in the Universe than other LABs We explain ionization deficits with long-term AGN variability We show that LABs rapidly disappear from the Universe Very bright targets (r = mag) to study AGN feedback, outflows, and Lyα escape fraction Schirmer+ 2016, MNRAS, 463, 1554

Discussion slide: Time-dependent inflow rate – Many sharp bursts (“flickering”) Fig. credit: Hopkins & Quataert 2010, MNRAS, 407, 1529 (see also Novak+ 2011, DeGraf+ 2014, Sijacki+ 2015) c c Quasar phases Major merger 1 million years

Discussion slide: Broad-band selection of low-z LABs Low-z LABs are well separated in broad-band data due to powerful narrow-line emission. All brighter galaxies in CFHTLenS Why haven't you heard about them? Extremely rare: 3-4 Gpc 3

Discussion slide: Selection: searching in SDSS... 98% spurious detections! Apply to SDSS data base: We overlooked: low-z LABs, the most luminous NLRs and outflows for 10 years! Bright, but rare: 4 Gpc –3 or deg –2

Discussion slide: Pre-discovery of J1155 – 0147 in 2001 Pre-discovery by QUEST ~2001; Chandra follow-up (PI: Coppi) in 2003, never published! OAN Venezuela; Photo credit: CIDA

Discussion slide: IR response to a finite AGN pulse Dusty torus models with increasing thickness Time axis units: Light travel time to sublimation radius (t=1) Figure credit: Adapted from Hönig & Kishimoto 2011, A&A, 534, 121 NIR (2.2 μm) MIR (8.5 μm) Finite pulse, duration t=0.5 MIR time lag: ~ years

Discussion slide: More images of low-z LABs Bipolar Unipolar Bipolar MultipolarBipolar Unipolar Unipolar / smooth SmoothTrain wreck Multipolar