automated analysis: sdss, boss, giraffeiac.es/congreso/itn-gaia2013/media/allendeprieto3.pdf · •...

Automated analysis: SDSS, BOSS, GIRAFFE

• Tests with MILES spectra (R~2000) from the INT (Sanchez Blazquez et al. 2006)

• The same code (FERRE)• Fitting data calibrated in flux and continuum-

normalized

Software

• Gaussian LSF (fiber, wavelength)• Quadratic interpolation of fluxes• Normalization by blocks• Successful tests performed on MILES library

Fittings to MILES spectra

Tuesday, August 27, 2013

Continuum on

MILES parameters (Cenarro et al. 2009)

ThisWork

[Fe/H] Teff logg

Distributions of residuals

Continuum off

[Fe/H] Teff logg

MILES parameters (Cenarro et al. 2009)

ThisWork

Distributions of residuals

Recent trends in spectroscopic studies• 3D model atmospheres: a beginning• full NLTE: good progress for hot stars, but …• Data archival: survey projects going on with

massive archives that become public (low-res: SDSS, SEGUE, GALEX) (high-res: Elodie, S4N)

• Analysis automation: a beginning• Breaking the Z barrier

The Desirable future• 3D model atmospheres• full NLTE• A pending observational test for solar-type stars:

center-to-limb variation of the solar spectrum• Data archival: VOs (including both observations

and models)• Stronger efforts to measure/compute atomic data• Stronger efforts to use the newly available

atomic data• Full analysis automation• R – an ignored variable?

Carlos Allende PrietoIAC

Galactic Surveys

Other projects and analysis strategies

Overview

• eBOSS, BigBOSS (DESI), HETDEX, WEAVE, 4MOST

• Data mashup: astrometry, photometry, spectroscopy

• Observing Galaxy simulations• Discovery and followup of interesting

targets: HVS, UMPS, CEMPS, RCrBs…


SDSS• BOSS (2009-2014): redshifts for 1.5 million

LRG to z=0.7 • eBOSS (2014-2020): extension to larger

redshifts using emission-line galaxies


13

Kitt Peak 4-m (Mayall) at Kitt Peak, Arizona USA today...

Capable of • holding heavy corrector• 3 deg. field

Dec. 6, 2011 David Schlegel P1 Science Overview

10 spectrographs

Mayall with BigBOSS

Huge Volume of universe with 3-degree field5000 robotic fiber positioners10 spectrographs15 million spectra!

Key of BB Instrument: 5000 Spectra per pointing via Robot Positioners

• 5000 positioners put fiber at target position

positioner

Spectrograph

fibers

Focal Plane filled with positioners

focal surface

HETDEX

DEX stars simulation from Besançon model


spectra


DEX stars analysis (KM stars)


DEX stars analysis (FG stars)


WEAVE


4MOST


Data flow CCDs single exposure flow• BigBOSS 10x(1+4) 0.6 GB 0.0005

GB/s• HETDEX 75x2 0.8 GB 0.002

GB/s • Gaia 100 (2 GB) (0.1

GB/s)• LSST 200 6 GB 0.3

GB/s

LSST will take 30 TB/night and 100 PB in 10 years

Big data and the cloud• Trends are changing in observational

astronomy• Hand by hand, instrument development and

computing are creating a new generation of machines geared to speed up discovery

• The biggest telescopes are, at least partially, not following that trend

Big data and the cloud• Supercomputing is widely embraced for

modeling and interpreting the data (plain good-old physics)

• Virtual observatories are developing quickly to ensure the legacy value of the data

• High-throughput computing widely adopted for large-scale projects, but only modest use of ‘cloud’ services (e.g. HETDEX)

Data mashup• Typical use of data is concentrating on a

specialized data set• This must change now with projects such as

Gaia• Analysis requires combining appropriately

different types of data• Bayesian statistics offers the framework to a

combined analysis of astrometry, photometry and spectroscopy


Observing simulations




Rahimi et al. 2012

Discovery and follow-up of interesting targets• HVS• LMWD• CEMPS• RCrBs• UMPS

Image from J. Norris


Structure of the halo• Monolithic collapse

and intensive accretion

• A dual halo split in rotation and [Fe/H]?

• Only place in the Galaxy where full orbits and chemistsry are preserved: ideal for stellar archaelogyJohnston & Bullock simulations

Chemical evolution• Big bang

nucleosynthesis• Stellar

nucleosynthesis: hydrostatic equilibrium, AGB

• Explosive nucleosynthesis• ISM spallation

• Also destruction…

Early Chemical Evolution

• Fast enrichment • Extremely few

stars expected (and found) at [Fe/H] < -4

• Large scatter in abundances at [Fe/H]<4

Big Bang Nucleosynthesis

Figure from Edward L. Wright

• Chemical abundances of the oldest stars constrain our model of the universe.

• Large discrepancy between CMB and stellar Li abundances

R-process is universal

Sneden et al. 2003

• Oldest stars provide pure information on single SN events

• Nucleosynthesis patterns then and now seem to match in cases

• The fraction of carbon-rich stars increases at low [Fe/H]

Abundance ratios

Chiappini et al. 2011Frebel 2010

Mg/Fe

Ca/Fe

Ti/Fe

Y/Ba

Only two stars currently known at [Fe/H]<-5!!

Discovery space• Preston/Shectman/Beer

s

• Hamburg-ESO survey (Christlieb+)

• SDSS (Yong et al. 2012, Bonifacio et al. 2012)

Apache Point ObservatoryNew Mexico, USA

BOSS spectra • More resolution

• More spectral coverage

• More sensitivity

• Deeeper into the halo

• Privileged access to IAC

• >100,000 spectra in hand!

BOSS analysis• SEGUE obtained >300,000 stellar spectraBetween 2008-2010• SEGUE’s pipelinecan be used to comparewith results from BOSS• New analysis for BOSS spectra represents asignificant improvement

Discovery process1. Skim through BOSS database to pick the

best candidates to have [Fe/H]<-42. Follow those up with higher quality: 4.2m

WHT/ISIS, 10m GTC/OSIRIS3. Investigate those that pass all the filters:

8m ESO/VLT, 10m GTC/OSIRIS, 10m HET/HRS (maybe HORUS)

HORUS-P

Led-ThAr hollow-cathode lamp

48

Summary• Astrometry: Hipparcos, UCAC3 , Gaia• Photometry: 2MASS, UKIDSS, VHS, SDSS ,

PanSTARS, GALEX, WISE, LSST• Spectroscopy: Various SDSS low-resolution

surveys, LAMOST, ARGOS, APOGEE, RAVE, Gaia-ESO, GALAH, DESI, HETDEX, WEAVE, 4MOST, MOONS


Summary II• Data indigestion?• Stress should be placed on automated

analysis• And on a rigurous analysis of combined data

(Bayesian framework)• Parametric models, increasingly

sophisticated, to become a workhorse. Are they Ready?

• Data can be directly used to determine distribution functions across the Galaxy to be directly compared with numerical simulations of all kinds to be directly compared


Conclusions• We are living a golden era for the study of the

Milky Way• Gaia flies at the end of the year, first catalog

probably out around 2016 and final catalog around 2020

• Now is the time to get ready to use Gaia’s data, and in particular to squeeze the information content in the combination of Gaia plus the other spectroscopic surveys

• Now is the time to sharpen our tools for automatic analysis and model-based interpretation


automated analysis: sdss, boss, giraffeiac.es/congreso/itn-gaia2013/media/allendeprieto3.pdf · •...

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