The MUFASA Project

The MUFASA Project
Cosmological galaxy formation simulations
with meshless hydrodynamic
Romeel Davé (UWC/SAAO/AIMS)
Robert Thompson (NCSA)
GIZMO-MUFASA
—  GIZMO: New “meshless” (moving mesh) cosmological
gravity+hydro code by Hopkins (2015).
—  Star formation (H2-based), minimal ISM pressure
—  11-element chemical enrichment: Type II/Ia + AGB
—  Radiative cooling, including metal lines & Compton
—  Kinetic winds (+ SN heating)
—  Quenching feedback via “radio mode”
—  Black hole growth & “quasar mode” feedback (TBD)
Advantages of GIZMO
Fixed Mesh
GIZMO
Feedback is
the key!
—  Star formation feedback:
From FIRE (Muratov+15)
hi-res zooms which
include SNe, radiation
pressure, stellar winds.
Muratov+15: η=M*-0.35
—  Quenching feedback:
Keep the hot gas hot
(Gabor+RD12) for
Mh>Mq=1012+0.48z
(Mitra+15)
Gabor+RD 2012
MUFASA runs
—  Cosmological “random” volumes:
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2x5123 particles, 12.5, 25, 50 Mpc/h volumes
εmin = 0.125, 0.25,0.5 kpc/h resolution
M*,min = 107 M¤, 8x higher at each larger box.
Eventually 2x10243 particle, 25/50/100 Mpc/h.
—  Galaxy zooms (R. Thompson): ~0.1-1 L*,
2 refinement levels from 25 box (ε~90pc).
—  Group zooms (M. Rafieferantsoa): Mh~1013 M¤.
—  Cluster zooms (F. Durier): Mh~1014-1015 M¤.
—  Run at UWC on our clusters Pumbaa and Timon.
Cosmo sims in a couple months, rest by late 2016.
Stellar mass functions
Somerville & RD 2015
The Trouble with Hydrogen
—  HI is not a direct prediction of models! Must subdivide H
gas into ionized, neutral, molecular.
—  So far, fairly simple self-shielding & H2 prescriptions have
been used.
—  Crucial issue: CGM neutral gas. There’s a lot! Cold cloud
masses may be ~103-4M¤ (Crighton+15) << anything sims
can resolve.
HII
HI
H2
Stars
self-shielding
H2 prescription
CGM HI absorption:
Thom+11
Gas properties
Wanna see something
really scary?
SPHGR(-yt)
(Robert Thompson)
—  SPHGR: “One-touch” galaxy catalog generation from
a simulation snapshot (written in Python).
—  Now incorporating into the yt package (SPHGR-yt),
which adds much more functionality.
—  Runs galaxy finder, halo finder, cross-correlates.
—  Creates hdf5 file containing galaxy catalogs at every
snapshot (redshift), including all galaxy properties
e.g. M*, SFR, MHI, Z, J, r1/2, …, also with halo info.
—  Magnitudes/spectra using LOSER. Merger trees,
movies… Light cones?
https://bitbucket.org/rthompson/sphgr
Summary
—  MUFASA: galaxy formation simulation suite with
state-of-the-art feedback covering a wide dynamic
range.
—  Matches GSMF from z=4 to 1 (0?) to within cosmic
variance uncertainties.
—  Also can match HI,H2 properties, but subject to how
one apportions the gas phases.
—  Public catalogs will be provided in yt hdf5 format,
including basic reading/analysis tools. (~3-6 mos?)
—  Working on noise, instrumental effects, etc to make
“real” images (see Ed Elson’s talk)