The Multiphase gas cycle and star-formation in the CGM of a distant radio galaxy Matt Lehnert (IAP, Paris) MS0735.6+7421 credit: McNamara & Bizan (Chandra press release)
AGN-global heating and entropy fmuctuations AGN-global heating and entropy fmuctuations Ideas presented here are from and inspired by Voit, Sharma, McCourt, Churazov, and collaborators. From theoretical studies of low redshift clusters, multiphase ICM develops from global heating and cooling balance, e.g., radio galaxies mechanical energy and accretion. While global heating may balance the overall cooling, the energy injection into gas can still cause local cooling and fragmentation through entropy fluctuations and instabilities, leading to turbulent clouds in the CGM. Radio galaxies good for phenomenological studies of CGM
The “Spider web” The “Spider web” Ly-alpha + HST 814W J-band + Dynamics with SINFONI 33” 22” Best studied radio galaxy embedded in a proto-cluster … at z=2.16, has a high stellar mass, ~few x 10 11 solar masses, giant Ly-alpha halo … X-ray emission ... Jets are powerful, will pump about 10 60 erg or more into the halo – about the binding energy of a massive galaxy. Miley et al. (2006), Kuiper et al. (2011), Carilli et al. (2002)
Difguse star formation Difguse star formation Deep UV imaging from HST g 475 with galaxies removed to emphasize diffuse light g 475 +I 814 +J 110 +H 160 300x300 kpc Ruled out faint cluster galaxies, nebular continuum, scatter QSO light, etc. favoring in situ star formation Hatch et al. (2008; 2011)
Dissipation of mechanical energy Dissipation of mechanical energy SPITZER IRS observations suggest strong dissipation of turbulence in the warm molecular gas through slow molecular shocks … but where is this taking place? Ogle et al. (2012)
Extended CO(1-0) emission Extended CO(1-0) emission Large halo of CO emission. Not from the galaxies, VLA sensitivity rules that out Emonts, Lehnert, Villar-Martin et al. (2016, Science)
Extended CO(1-0) emission Extended CO(1-0) emission The velocity differences between the gas and galaxies are vastly different …. No companions detected in VLA data Emonts, Lehnert, Villar-Martin et al. (2016, Science)
Extended CO(1-0) emission Extended CO(1-0) emission Velocity of the CO is much different from that of the gas. Not from the galaxies. Dynamical time of the CGM is about 100 Myrs and so it settled for a long time. Massive stars live an order of magnitude less. Emonts et al. (2016), Hatch et al. (2008)
Star forming like galaxies but in a halo Star forming like galaxies but in a halo How do stars form in a halo? Emonts, Lehnert, Villar-Martin et al. (2016, Science)
Questions Questions These results raise a lot of questions: 1) Is the gas really in the CGM and if yes, what is its source? 2) How do stars form in such gas? 3) Does the radio jet also cause cooling in the halo? 4) Is this analogous to star formation seen in clusters at low redshift? Perhaps we can address some of these questions by looking at the chemistry and energy dissipation in the gas.
Extended atomic and molecular line emission Extended atomic and molecular line emission [CI] 3 P 1 - 3 P 0 and CO(4-3) with ALMA at low spatial resolution [CI] trace low density molecular gas, while CO(4-3) traces denser, more highly excited gas and it all looks like the CO(1-0). Emonts, Lehnert, De Breuck et al. (2017, MNRAS submitted)
Abundance and excitation Abundance and excitation Abundances and Excitation of the molecular gas in the IGM Excitation and abundance, X [CI] /X H2 ~2x10 -5 , similar to the MW and other proto- cluster galaxies. The CGM is similar to gas in galaxies, “metal rich”, low excitation, not “diffuse” Provides another link between gas and SF Emonts, Lehnert, De Breuck et al. (2017, MNRAS submitted)
ALMA observations of water ALMA observations of water In cycle 1, we observed the Spider web for ~50 minutes in: H 2 0 2 11 -2 02 @ 753.03 GHz [CI] 3 P 2 – 3 P 1 @ 809.34 GHz CO(7-6) @ 806.65 GHz 235 GHz continuum (~775 GHz continuum in the rest-frame) These observations were intended to: *trace the diffuse and dense molecular gas *trace the dissipation of mechanical energy through slow molecular shocks in dense gas. Address questions of: What is the impact of the radio jets on the dense circum-nuclear molecular gas? Where does the mechanical energy go? Is some of it dissipated through turbulence in the dense molecular gas?
The Quantum mechanics of water The Quantum mechanics of water 3 quantum numbers, J, K A , K C with permanent dipole, μ. These are total angular momentum and its two projections. ΔJ=0, +-1. ΔK A , ΔK C = +-1 or +-3 plus 3 unequal moments of inertia means large N of closely spaced transitions Large dipole moment allows for fast dipole transitions. H 2 O is an important coolant for dense gas with T~100-1000 K Levels determined by T ex , which can be either T rad or T collisional Shocks IR pumping
Dew drops in a dusty web Dew drops in a dusty web Not in the radio galaxy, but in the halo Gullberg, Lehnert, De Breuck et al. (2016)
Dew drops in a dusty web Dew drops in a dusty web Strong water emission implies dissipation in slow, 10-40 km/s, molecular shocks in dense gas, 10 3 to 10 5 H 2 cm -2 . Rapid dissipation of mechanical energy from the jet. Water winks on and off as energy dissipates. Gullberg, Lehnert, De Breuck et al. (2016)
A “model” A “model” Do the clouds dissipate turbulence rapidly enough to form stars? ALMA cycle 4 and 5 proposals to find this out.
Some fjnal thoughts Some fjnal thoughts We need to figure out multiphase CGM forms. What is the balance between heating and cooling? How does this regulate galaxy growth? How far can the gas cool? Down to stars? How is the kinetic energy dissipated? How does this depend on the environment – halo mass, epoch, location in large scale structure? Is the Spiderweb now becoming an interesting study of how stars form? Advantage: projected against the faint sky, not ‘within’ a galaxy. Radio galaxies provide a nice test bed for understanding the gas physics phenomenology, but not necessarily for CGM demographics.
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