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gal* : Tools to Model the PS1 Galaxy. Mario Juric Harvard-Smithsonian Center for Astrophysics, Hubble Fellow. TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: A A A A A A A A A A. About the Author. Mario Juri ć - PowerPoint PPT Presentation
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Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
gal*: Tools to Model the PS1 Galaxy
Mario JuricHarvard-Smithsonian Center for Astrophysics, Hubble Fellow
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
About the Author
Mario Jurić Institute for Theory and Computation, Harvard/CfA
Interests: High Data Volume Astronomy (Surveys) Galactic structure,
formation, and evolution
Projects: SDSS PS1 (KP5) LSST (MWL&V, ImSim)
This talk: Tools forMW structure sciencewith PS1.
DadMom
The Milky Way Components: Fingerprints of Formation and a
Laboratory for Dynamics
• Thin disk (gas acc., mergers)
Thick disk (merger history, secular evolution)
Bulge and bar (merger history, secular evolution)
Stellar halo (early formation, history of assembly)
Galactic center Globular clusters (formation, dynamics)
The Dark Matter halo Milky Way satellite system
(MW assembly, galaxy formation, dark matter properties)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Reconstructing Galactic Formation and Evolution
Name of the game: measuring the number, normalizations, shapes and histories of Galactic components (including MW satellites).
How many pieces, which piece came from where and when, and where to look for the most interesting (usually: the oldest) piece?
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Obstacles
Observational Lack of data Largely resolved (SDSS, PS1)
Inferential Lack of capability (tools) to probabilistically
infer the underlying physical reality The primary obstacle
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
SDSS: Galactic Model Parameters
Disk + Inner Halo models
Z
R
Juric et al. (2008)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Unrecognized Multiplicity An unresolved multiple
system mistaken for a single star
Luminosity changes, color (approx.) does not
Error in distance estimate
Early types: >60% (Duquennoy & Mayor 1991)
Late types: 20-40% (Reid et al. 2006; Reid & Gizis 1997; Fischer & Marcy 1992)
Ground Truth Inference
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
SDSS: Unrecognized Multiplicity An unresolved multiple
system mistaken for a single star
Luminosity changes, color (approx.) does not
Error in distance estimate
Early types: >60% (Duquennoy & Mayor 1991)
Late types: 20-40% (Reid et al. 2006; Reid & Gizis 1997; Fischer & Marcy 1992)
Possible to statistically correct for, if the binary fraction is known
Effect of binarity on derived model parameters
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
SDSS: Galactic Model ParametersJuric et al. (2008)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
SDSS: Disk Model Likelihood Surfaces X-Sections Best fit:
Z0 = 25 pc H1=245 pc, H2=740 pc L1=2.15 kpc, L2=3.3 kpc f=13% Reduced c2=1.6
Strong covariance between individual parameters
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
SDSS: Halo Model Likelihood Surfaces X-Sections
Inner halo nH = 2.8 qH = 0.6
fH = 0.5%,
Obtaining full posteriors rises in importance as we begin examining the contributions of more tenuous components (accreted vs. in situ halo, metal weak thick disk, etc.)
Especially when contamination due to imperfect star-galaxy separation is taken into account.
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
SDSS -> PS1 (GAIA, LSST, …)
1. Full forward-modeling of the observed datasets Inputs: model parameters Outputs: catalogs (to be compared w. real data)
2. Probabilistic (Bayesian) inference of model parameters Posteriors Evidence
Primarily a technical problem Code complexity and speed
galfa
stga
lfit
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
galfast – fast Galactic model sampler
A realistic simulation of the observed N-D (stellar) sky (density, kinematics, abundances, …)
Inputs: (arbitrary) input models (density, kinematics, dust, …), and stellar-parameter-magnitude relations (e.g. isochrones). Observational system definition (obsv. errors)
Outputs: mock catalogs, counts, density maps, likelihoods
Basic algorithm: sampling from a multidim. space of (X, Y, Z, absmab, Fe/H, …) over the survey volume (PS1: ~1011 samples)
Simple, trivially parallelizable, and computationally expensive
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Inputs
Color-Magnitude relations (CMRs) luminosity-metallicity-color (SDSS bands) relations for MS+RGB (empirical
calibrations), H+He WDs (Bergeron models), RR Lyrae (empirical), BHB stars (empirical)
3D dust maps 3D data cube Amores & Lepine (2005) exponential + small-scale clumpiness to asymptote to
SFD’98 at infinity
Stellar Number Density Exponential disk(s), power law halos, or a 3D data cube (e.g., N-body simulation
result) Metallicity
Ivezic et al. (2008) model Kinematics
Bond et al. (2010) model
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Example Outputs: Star Counts (in Shells of Apparent Magnitude)
r=15
r=29
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
CMR+Dust Map test: galfast vs SDSS @ b=50Juric et al. (in prep)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
galfast vs SDSS: b=50Juric et al. (in prep)
FG
K
M
HB
FG
K
M
HBWD WD
QSOs
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
CMR+Dust Map test: galfast vs SDSS @ b=0
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Galactic Model Test: galfast vs SDSS @ l=60, b=45
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Comprehensive Q/A
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Sidenote: Bayesian Estimation of Stellar Parameters (galstar)
Uncertaintiesof parameterestimates
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Sidenote: Bayesian Estimation of Distance and Extinction
ML estimate
Expectationvalue
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Sidenote: Implementation
N-Body output
Analytic laws
Density cube
Monte Carlo draw of position, absolute
magnitude
[Fe/H] Photometry
3D extinction map
KinematicsAstrometry
Prop. Motion Multiplicity
Catalogs
Statistics
Posteriordensities
… additional postprocessing …
Observational errors
Inputs/Models Generator Postprocessing Output
galfast: schematic execution overview
A really fast direct 4D PDF sampler: r(X, Y, Z, M) or r(l, b, DM, M)
Stellar properties given as P(prop|X,Y,Z,M) and assigned in postprocessing
Requirements:
1. Flexibility (arbitrary inputs and outputs)
2. Speed (GPU accelerated implementation)
Juric et al. (2010)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Speed
GPU speedup for 315 sq. deg. footprint, 0.5% photometry
0
50
100
150
200
250
T(C
PU
) / T(G
PU
) . Speedup
Runtime for 315 sq. deg. footprint, 0.5% photometry
0.01
0.1
1
10
100
1000
10000
100000
Tim
e (s
econ
ds)
.
GPU
CPU
Tesla S1070 (single GPU) vs. Xeon E5405 2.0GHz (single core)
For photometric precision ~0.005mag:
~240x speedup
Depending on the requested level of realism and outputs, can generate a mock (oversampled) PS1 in <10 hrs.
(Jan2010 AAS poster)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Work in Progress: galfit
Even with a fast generator like galfast, it’s unfeasible to run it for every likelihood computation
Instead, record the scattering probability matrices from a single run:
Compute subsequent models without going through the Monte Carlo stage
Will allow us to compute posterior probabilities for the full PS1 stellar dataset
galfit galfast
iesprobabilitn transitiox;x ofmatrix sparse :result
x,..,x,xx:stars of sampling
xx:star single a
N21
p
nnnn survey
survey
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Code: mwscience.net/galfast (the usual PS1 ps1sc pass.)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Data Products: Mock Catalogs
Mock PS1 catalogs Mocks with known ground truth that is as close as possible to the
real Galactic model PS1 Footprints, flux limits, photometric errors, completeness,
masking, … We will begin producing these as soon as the above are assessed.
Uses: Optimizing candidate selection algorithms (dwarf galaxies,
streams, brown dwarfs…) Estimating selection functions …
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Adaptation to PS1: Photometric System Transformations
Eddie Schlafly
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
PS1 KP5: Wide AreaImage by Eddie Schlafly
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
KP5 Applications: Stellar Halo Populationsde Jongh et al. (2010)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
KP5 Applications: Quantifying Halo SubstructureBell et al. (2008)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
KP5 Applications: Quantifying Dwarf Selection Function
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
CFHT: Halo density profiles out to 35kpc
• Solid: CFHTLS data
• Dashed: Juric et al. (2008) c/a=0.64 oblate power-law halo
• Note: J08 models fitted to D<15kpc halo
• Fairly good agreement for W3 (north) and W4 (south) fields for D<20kpc
• Deviation at large distances
Sesar, MJ & Ivezic (subm.)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
CFHT: Halo density profiles out to 35kpc
• q=0.7, n=-2.6 inner profile
• q=0.7, n=-3.8 outer profile
• transition at Rbreak ~ 28kpc
• no evidence for triaxiallity
• no evidence for change of oblateness
Sesar, MJ & Ivezic (subm.)
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
PS1 Analog: Medium-Deep Fields
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.
Summary & Outlook (~next 6 months)
gal*: A set Galaxy modeling tools for PS1 Currently being applied to SDSS & CFHT
Calibration, calibration, calibration! Nearly everyone is interested in this, efforts should be
coordinated PS1 Test #1: Repeat Sloan
Same area, same tools -> same results.
Galactic structural parameters and density substructures Deep halo profiles (MDF+calib field (?) stacks) Mock PS1 catalogs
Soon: Disk density (stars+dust) model-free 3D mapping
Modeling the PS1 GalaxyMario Juric <[email protected]>, Tuesday, Aug 31st, 2010.
Pan-STARRS PS1 Collaboration Meeting, Queens University, Belfast, U.K.