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HI in Active Galaxies

Andrew Baker Rutgers, the State University of New Jersey



Archaeological evidence: M­relation
For (nearly) all galaxies with spheroids: black hole mass correlates with spheroid velocity dispersion growth of black holes and spheroids must be coordinated (fueling and/or merging).



Tremaine et al. (2002)




Coordinated fueling: nearby AGN hosts
Narrowline AGN hosts in SDSS: high M* and * but "black" rum younger stellar ages (not just in nucleus!) coordinated fueling of star formation and light rum


accretion is key. Kauffmann et al. (2003)



Coordinated fueling: PG QSO hosts
[NeII] 12.8 m QSO hosts in midIR: PAH features and lowionization lines correlate with 60 m just like starburstpowered ULIRGs dusty starbursts power a substantial fraction of farIR luminosities.

PAH 7.7 m

Schweitzer et al. (2006) 60 m




6 m


Coordinated fueling: cosmic downsizing
selected at 0.5­2 keV: Local black hole mass function agrees with {B, 0.5­2 keV, 2­10 keV} AGN luminosity function if more massive black holes finish growing earlier.

90% done

Hasinger et al. (2005)



Marconi et al. (2004)


Is HI relevant to coordinated fueling?
A priori reasons for skepticism... (1) Large HI reservoirs are at large R, where dynamical timescale is high and angular momentum loss slow. (2) Molecular gas dominates at small R­ due to higher midplane pressure and/or traumatic merging­ and anywhere stars form.


Blitz & Rosolowsky (2006)


The Nuclei of Galaxies (NUGA) survey
Core sample: 12 spirals with Seyfert/LINER nuclei mapped at high resolution in CO(1­0) and CO(2­1) with IRAM PdBI.

GarcМaBurillo, Combes, et NUGA team



HI observations of NUGA spirals
VLA mapping: 12 core NUGA targets + 4 more spirals mapped with C and D arrays (7 Seyfert + 7 LINER + 2 HII region).





Haan et al. (2007)


Results: HI morphologies
Null results: no dependence of AGN type on number of companions; only weak trends with HI mass and RHI/R Suggestive results: (1) 80% of LINERs vs. 0% of Seyferts have HI rings. Relics of expired bars? Hunt & Malkan (1999): LINERs also tend to have inner stellar rings. (2) 40% of Seyferts vs. 0% of LINERs have centrally concentrated


opt.

Haan et al. (2007)



HI components.


Results: estimated gas flows
Following GarcМaBurillo et al. (2004): + derive stellar potential from NIR/MIR image + at each pixel, calculate force/mass (Fx,Fy) and torque/mass t(x,y) = xFy ­ yFx + azimuthally average t(x,y), weighted by gas column density N(x,y), to obtain d(R)/dt Large R (HI): net d/dt < 0 gas flows inward. Small R (CO): net d/dt > 0


gas flows outward.




HI absorption in elliptical AGN hosts: infall?
Initial result from van Gorkom et al. (1989) and references therein: ~ 30% of ellipticals (z < 0.13) have associated HI absorption, either systemic or redshifted. In NGC5128, redshifted absorber is compact and systemic absorber is extended former is at small radius (van der Hulst et al. 1983).


van Gorkom et al. (1989)


HI absorption in elliptical AGN hosts: outflow!
More recent results... Morganti et al. (2001): 1 of 10 FR I, 3 of 4 narrowline FR II hosts (z < 0.22) are detected in absorption; 2 of 3 FR II detections are blueshifted. Vermeulen et al. (2003): 33% of radioloud AGN (z < 0.8) show HI absorption features, more frequently (and more highly) blueshifted than redshifted.



HI absorption in spiral AGN hosts: outflow
Morganti et al. (2005): 3C305 produces most of its blueshifted HI absorption against its western lobe rather than against its nucleus. contours = continuum greyscale = absorption



HI absorption in spiral AGN hosts: rotation?
Gallimore et al. (1999): only NGC4151 of 13 radioloud Seyfert nuclei mapped shows HI absorption on small scales. Otherwise: + HI kinematics dominated by rotation on ~100 pc scales + modest HI inflow rates are possible but not required + typical NH(Xray) >> NH(HI) due to ionized/molecular gas






An interesting environmental paradox
Kauffmann et al. (2004): optical emissionline AGN prefer poor environments. Left: fraction of galaxies containing L
[OIII] >

107 L



AGN of those with 01, 711, or >12 "neighbors". Kauffmann et al. (2008): radioloud AGN prefer rich environments. Right: galaxy counts vs. projected radius for radioloud (solid) and
radioquiet (dashed) emissionline AGN.


An even more interesting explanation
Kauffmann et al. (2007): locally, + optical emissionline AGN prefer poor environments because there's more cold gas (fuel); + radioloud AGN prefer rich environments because there's more hot gas (fuel and/or jet "working surface"). Implications if true: (1) Cold gas (e.g., HI) may not fuel radioloud AGN at all. (2) Radioloud emissionline AGN are more common at z > 1, because massive galaxies inhabiting less massive haloes


can accrete both cold and hot material.


Thoughts on the future
ALMA ideal for studying AGN fueling: can map "cold" molecular gas emission near nucleus at high angular resolution.

For HI: z ~ 0.5 is not the most interesting "high" redshift regime in terms of galaxy and halo properties. If anything at z ~ 1­2 is plausibly detectable with subSKA collecting area, conquering RFI in lowfrequency windows should have high priority.



Conclusions
Star formation and accretion are apparently coordinated in massive galaxies at all redshifts. Cold gas fuels both star formation and accretion in optical emissionline AGN; it's doubtful how much is HI per se. HI absorption against radioloud AGN traces a mixture of infall, outflow, and rotation; key fuel may be hot gas. Also: see Bjorn Emonts poster on HI as a tracer of dynamical


state in powerful radio galaxies!