What matter(s) around galaxies? Shining a bright light on the cold phase of the CGM

Transcription

1 What matter(s) around galaxies? Shining a bright light on the cold phase of the CGM Sebastiano Cantalupo ETH Zurich In collaboration with: MUSE GTO Team (ETH, CRAL, Leiden, AIP, Toulouse, Gottingen) + Cosmic Structure Formation group at ETH & J. Xavier Prochaska, Sammy B. Slug, Piero Madau, Fabrizio Arrigoni-Battaia, Joe Hennawi, Martin Haehnelt Cantalupo et al., Nature, 2014

2 Talk Outline & Key Questions What are the morphological and physical properties of the CGM on both small and large scales? (key questions #2 and #3) Introduction: detecting the CGM/IGM in emission Observational surveys (NB, MUSE, MOSFIRE) and inferred properties of the CGM How do galaxies affect cooling in the CGM? (key question #4) Open questions/summary Cantalupo et al., Nature, 2014

3 Detecting Cosmic Gas Classical approach: in absorption. pro: ability to detect low-density gas including metals. con: typically only 1D information (or sparse 2D) LLS/DLAS = Dark galaxies? Filaments? IGM? CGM?... difficult to say without direct detection. quasar Direct detection in emission: Fluorescent Lyα (Hogan & Weymann 1987;Gould & Weinberg 1996; Zheng & Miralda-Escude 2005; Cantalupo+05,07; Kollmeier+06,10; Cantalupo+12) external ionizing flux fluorescent emission QSO fluorescent HI HI Absorption part (1D info) emitters ionized region (HII) HII recombinations Self-shielded gas (slab): mirror emission -> ~60% of incident ionizing radiation converted to Lyα (but see Cantalupo+05). Fully ionized gas: proportional to gas density squared.

4 log(sb) (cgs/arcsec 2 ) How bright is fluorescent emission: simulations Simulated Lyα images at z~2.5 (20Å NB; no noise/psf) centred on a ~10 13 M sun halo hydro-simulation (RAMSES) + Radiative Transfer (RADAMESH, SC+12) QSO fluorescence Cantalupo NB & MUSE 1h -18 MUSE medium MUSE deep UVB+Stars UVB fluorescence cmpc How to detect it? MUSE FOV UVB+Stars +QSO cmpc 1) Look around bright quasars 2) Stack for statistical detection (see Sofia Gallego s talk) 3) Integrate for 100+ hours away from quasars

5 Highlights from Narrow-Band imaging survey of Quasar fields at z~2.3 Compact fluorescent emitters without stellar counterparts ( Dark galaxies ) SC+12 CGM in emission around a bright galaxy qso (3 ) Giant Quasar Nebulae: the Slug 1 (500kpc) SC+12 Morphology and SB compatible with cold filaments + other 25 QSOs (FLASHLIGHT Keck+GMOS survey; Cantalupo+, in prep.; Arrigoni-Battaia+, in prep.; see next talk) qso main results: - Giant Nebulae (>100kpc) are rare in NB surveys (<10%) - Morphology and kinematics compatible with CGM/IGM but SB is too high for expected gas densities > dense clumps required (see later). Cantalupo+14, Nature

6 Are Giant Nebulae really rare? A MUSE snapshot survey around z~3.5 QSOs 45 ~350 kpc Targets: brightest radio-quiet QSOs at 3<z<4 (and two radio-loud, R1 & R2) Exposure times: 1h only total integration ( snapshot survey) White-light images obtained by collapsing the datacube along the wavelength direction. Borisova, Cantalupo+, 2016

7 45 ~350 kpc MUSE observations of QSOs at z~3.5: 100% detection rate of giant nebulae! Targets: brightest radio-quiet QSOs at 3<z<4 (and two radio-loud, R1 & R2) Exposure times: 1h only total integration ( snapshot survey) Optimally extracted pseudo-nb images with QSO PSF-subtraction obtained with CubExactor (Cantalupo in prep.) All nebulae larger than 100 kpc with various morphologies. Borisova, Cantalupo+, 2016

8 A 3D view of the Muse Quasar Nebula 3 (MQN03), 350kpc in size: CubExtractor (Cantalupo, in prep.) + VisIt QSO PSF and continuum subtracted cube 2σ~1x10-18 cgs/arcsec 2 350kpc 10A ~ 600km/s Borisova, Cantalupo+, 2016

9 2D Velocity maps: - no clear signs of rotation (with some exceptions); - radio-quiet nebulae (1-17) are kinematically narrow. Borisova, Cantalupo+, 2016

10 How do they compare with other Lyα Nebulae and haloes? Circularly averaged SB profile QSO PSF average profile redshift-corrected (all scaled to z=3) All giant quasar nebulae have similar SB profile and are consistent with fluorescence (including LBG Stack halo of Steidel+11) Borisova, Cantalupo+, 2016

11 Inferring the cold gas content of the Giant Nebulae: the Slug case Cantalupo+, Nature, 2014 Photon-pumping / Lyα scattering case (gas mostly neutral) Observed SB Recombination case (gas mostly ionized) cm -2 Inferred N(HI) cm-2 Inferred N(HII) a a b b NB: depends on Clumping Factor M(HI) ~ M( cold H) ~ 2.5x10 11 M M(HII) ~ M( cold H) ~ M /C 0.5

12 Comparison with simulations: more IGM clumps needed! N(H) cm -2 Simulation (all) Slug Nebula ionized case a C=1 Subgrid Clumping Factor (<1kpc) b N(H) cm -2 Slug Nebula neutral case a Text Slug Nebula ionized case a C=50 Subgrid Clumping Factor (<1kpc) b b Cantalupo+, Nature, 2014

13 Breaking degeneracies with non-resonant lines: MUSE HeII search NB (Lyα) c Cantalupo+, in prep.

14 Extended HeII detected with MUSE from part of the Slug (no rotation!): 12 continuum subtracted cube (9h) + CubEx v1.6 (Cantalupo, in prep.) kpc 2σ~3x10-19 cgs/arcsec 2 c 10A ~ 600km/s Cantalupo+, in prep.

15 Why is HeII missing from the Slug tail? 1) Tail Lyα emission due to photon-pumping / scattering ruled out by MOSFIRE Hα (and preliminary MUSE CIII) detection tail Lyα spectrum tail Lyα/Hα~10 consistent with Case B Recombination Leibler, Cantalupo+, to be sumbitted Hα spectrum qso b

16 Why is HeII missing from the Slug tail? High densities required 2) High densities and larger distances ~0.08 HeII/Lyα 0 Expected HeII/Lyα ratio (a) single-density clump scenario log (HeII/Lyα) D = 50 kpc D = 160 kpc -3 D = 350 kpc -3.5 D = 1 Mpc log(nh/cm -3 ) data <0.005! data (a) n clump ~ cc! (depending on actual distance) (b) (b) turbulent/lognormal density distribution scenario <n> cold =0.1 cc <n> cold =1 cc data <n> cold ~1-10 cc if log-normal σ >2.5 Cantalupo+, in prep.

17 Open Questions and Future Directions What sets the frequency, size and luminosity of the giant quasar Nebulae? (quasar lifetime, opening angle, halo mass, redshift, quasar luminosity, ) What is the origin of the IGM/CGM clumps traced by the Nebulae? (thermal/gravitational instabilities, quasar radiation effects, ) How this affects galaxy and QSO formation? (fast gas accretion, violent disk instability, ) Exploring a larger parameter space: - include lower luminosity quasars; - extend the redshift range to 2<z<3 (not possible with MUSE, KWCI required) Improving our theoretical understanding of IGM clump-formation : - hydrodynamical and thermal stability analysis (see Ann-Christine Vossberg s talk); - detailed comparison with observational data. Moving away from quasars: - detect average Cosmic Web filaments connecting galaxies and illuminated by the cosmic UVB (>50h-deep exposure with MUSE and/or KWCI required).

18 What happens when the CGM is illuminated or how to quench/regulate the SFR of galaxies? We understand everything about gas cooling [in the CGM] thanks to our hydrodynamical simulations, so we only need to focus on SN and AGN feedback. A Colloquium Speaker, IoA, Cambridge, ) removing the gas from the galaxy (e.g., SN feedback, ejective feedback ). 2) reducing/stopping cooling gas accretion from the CGM by changing cooling ion abundances ( preventive feedback ) The basics of the Cooling Function cooling function with UVB Main coolants: ion line Ion.Potential O 4+ OV[630A] ev Ne 5+ NeVI[400A] ev Fe 8+ FeIX[169A] ev Wiersma+2009 To kill the peak cooling rate we need to illuminate the CGM with soft X-ray photons

19 Soft X-ray emission from GALAXIES: linear relation with SFR Strickland+04 Rovilos+09 See also: Mineo+15 Soft X-ray (model) produced by SN bubbles, calibrated to reproduce observed SFR - Soft Xray relation. NB: X-ray binaries not included(yet)

20 Effect on the CGM cooling: Cloudy modeling for typical CGM cooling nh=10-3 cm -3 (δ~5x10 z=0) (δ~6x10 z=1) d=5 kpc from galaxy Z=0.03 Z Λ(n, T, Z, U*+UUVB) U* SFR d -2 nh -1 NB: for isothermal halo profile: U* SFR Mvir -2/3 (1+z) -1 heating dramatic effect of local sources on cooling rates of CGM gas (+ some extra heating). Cantalupo 2010

21 The hot-mode/cold-mode transition (Dekel & Birnboim 2006) revisited Result: transition depends on SFR. For high SFR there is no critical halo mass. Cantalupo 2010

22 Importance of this effect is confirmed by hydrodynamical simulations standard + local X-ray CGM ISM CGM ISM - Gasoline simulations (isolated disk) standard + local X-ray - SFR and total stellar Mass reduced by a factor of 2 - SFR regulated when critical SFR is reached (as in analytical model) - Less SN feedback required, improved rotation curve, more stable disk. Kannan,,Cantalupo+2014

23 Observational evidence for local source effect on CGM cooling? - absence of the main cooling line (OV630A) is difficult to probe directly. - indirect evidence: excess of O 5+ (OVI) or higher potential ions. COS-Halo Survey Tumlinson+11 data (points) simulations (lines) Oppenheimer+16 (EAGLE zoom simulations) Werk, Prochaska, Cantalupo+16 - clear excess of OVI close to star forming galaxies w.r.t. simulations without local radiation effect (e.g. Oppenheimer+16) See Jess Werk s talk and others on Thursday

24 Summary and open questions New technique to illuminate the CGM/IGM at high-z with the help of QSOs: Giant Lyα Nebulae with sizes up to 500kpc and various morphologies are ubiquitous around QSOs at z~3.5 (MUSE) and apparently less frequent in NB surveys at z~2. (key question #2). Is this a real redshift evolution or due to the observational technique? Modelling of both H-Lyα and HeII emission suggest that clumps with large densities (n>>10 cm -3 ) and small sizes (~pc) or log-normal/turbulent density distributions with large σ should be present on intergalactic scales around quasars. (key question #3) What is the origin of the clumps and their effect on galaxy formation and evolution? Local sources of X-ray radiation can greatly reduce CGM cooling (increasing N OVI ) and therefore regulate star formation without the need of strong ejective feedback at z<1 (key question #4). How this affects galaxy properties such as, e.g. disk angular momentum? Next future: - ultradeep MUSE surveys to trace largest filaments - new theoretical/numerical CGM models to resolve the small-scale physics Stay tuned!