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The Galaxy-CGM-UVB Connection
Kristian Finlator, NMSU June 2017 Collaborators: Romeel Davé; Caitlin Doughty; Benjamin D. Oppenheimer; Shuiyao Huang; M. Prescott; E. Zackrisson
The Galaxy-CGM-UVB Connection Kristian Finlator, NMSU June 2017 - - PowerPoint PPT Presentation
The Galaxy-CGM-UVB Connection Kristian Finlator, NMSU June 2017 - - PowerPoint PPT Presentation
The Galaxy-CGM-UVB Connection Kristian Finlator, NMSU June 2017 Collaborators : Romeel Dav; Caitlin Doughty; Benjamin D. Oppenheimer; Shuiyao Huang; M. Prescott; E. Zackrisson Modeling the CGM, the Galaxies, and the UVB Question 2 What is
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Method: Cosmological Simulation with a live UVB
Hydrodynamics + Matter
GADGET-3 (density-independent SPH; Hopkins+)
12 h-1 (= 17.74791851) cMpc simulation volume 2x5123 or 2x2563 particles ~100-200 pc hydro resolution Star Formation Feedback 𝜃(M*) from Muratov+2015 “FIRE” zoom simulations “Live” UVB : Evolved on-the-fly using moment-based RT.
- Opacities from H, HeI, HeII.
- 24 energy bins (1-10 Ryd), 323 or 643 voxels.
Simulated Metal Absorbers Custom ray-casting code uses local UVB and all relevant transitions to compute ionization state, optical depths.
Tests I won’t show: ✓UV luminosity function at z≥5 (KF+2016b) ✓SFR density versus Madau & Dickson 2014 ✓CMB optical depth to Thomson scattering ✓UVB amplitude at z = 5
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50% Ionized Universe: Many Galaxies per HII Region
12 h-1 Mpc 12 h-1 Mpc : show galaxies’ positions
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Cut at MUV < -15: Few Galaxies Observable, even with JWST!
12 h-1 Mpc 12 h-1 Mpc
: gal’s w/ MUV < -15 There are 2. (Can you find them?)
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UVB is bright in ionized regions …and the spectral slope varies too!
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UVB inhomogeneous at z=7 (xHI = 20%)
CII: suppressed UVB CIV: enhanced UVB KF+2015
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SiIV/CIV Observations at z~6 support a soft, inhomogeneous UVB
KF+2016a (also Doughty+ in prep)
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CIV host galaxies: example, z = 5.75
NCIV=1.13x1013 cm-2 ZCGM = 10-3 -10-1 Z0 J𝞷 amplified 2-4x
- ver volume-average
Complex system with Δv ~200 km s-1 Aligned CII: simpler velocity profile
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Not one host galaxy per metal cloud
420 pkpc
x: position of absorber with NCIV=1013cm-2 slice depth = 50 km/s dots: all galaxies stars: MUV ≤ -17 box: 40 pkpc rad. ≈ 1 HST FOV
420 pkpc
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Local UVB enhances CIV
(Motivation: averaging
- ver sightlines; cf. Mark
Anderson’s talk)
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Local UVB enhances CIV, but CIV still underproduced at z=5.75
(Motivation: averaging
- ver sightlines; cf. Mark
Anderson’s talk) similar results: Keating +2016, Bird+2016; Nelson+; Rahmati +2016 difference from KF +2015: different
- utflow scalings
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Finding Hosts of Weak Absorbers at z=5: They’re Faint!
- More than half of the
hosts of systems with N~1013 cm-2 are fainter than MUV = -15.
- CIV hosts are much
brighter than OI hosts.
- Weak metal absorbers
are complementary tracers of faint galaxy formation.
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Takeaways: Q2 (CGM physical conditions)
At z ≥ 6, the CGM has [Z/Z0] = -1 to -3, with a small amount of primordial gas. The UVB amplitude is enhanced/suppressed around high/low-ionization absorbers. The effect grows stronger at z ≥6.
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