The SAMI Galaxy SurveySecond Public Data Release: Absorption Line Physics

ASA, Swinburne, 26th June, 2018Nic Scott, Jesse van de Sande & the SAMI team

SAMI data

› Optical integral field spectrograph covering ~ 3700-7500 Å

› S/N 1 – 50 per Å per spaxel (continuum), up to ~1000 achievable by summing spaxels

› ~10 emission lines and ~20 absorption features per spectrum

› ~ 100 spatially independent spectra per galaxy

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Allen et al. (2015)

SAMI Galaxy Survey

› Complete survey ~3000 galaxies› Mass and volume limited selection› z < 0.1, M* > 108, completeness ~ 80%› Spans a wide range in host halo mass› Full range in morphology

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Bryant et al. (2015)

Data Release 2: the galaxies

› 1559 galaxies from the GAMA 9h, 12h and 15h fields

› Fully representative of the full SAMI Galaxy Survey sample

› Except, no cluster galaxies included (at this stage)

› See Scott, van de Sande et al. (in prep) for full details in a few weeks

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Data Release 2: the data

› Fully processed data cubes› Aperture spectra (new)› Binned data cubes providing higher

S/N spectra (new)› Stellar kinematics (new) (JvdS+2017)

› Gas kinematics (Ho+2016)

› Emission line fluxes › Star formation rates (Medling+2017)

› Global stellar populations (new)(Scott+2017)

› Uncertainties, quality control metrics, flags etc.

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Data access

› All data will be made available through the AAO’s Data Central service (see Liz Mannering’s talk)

› Fully searchable interface, linking data from multiple Australian surveys

› SAMI DR2 data will become public on the 31st July

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Image credit: Liz Mannering/AAO Data Central

Highlight 1: The age – intrinsic shape relation

› Using projected shape and stellar kinematics, can infer the 3D shape of a galaxy

› Find a strong correlation between 3D, intrinsic shape and mean stellar population age

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Highlight 2: misalignment between gas and stars

› Compare rotation axis orientation of gas and stars

› Strong misalignments indicate likely external accretion origin of has

› Find a significant difference in early-type galaxies between high-and low-density environments (Bryant + submitted)

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136$Cluster$galaxies$484$Field/group$galaxies$

Why?

› Because we told the TAC we would› Because open data and reproducibility are important› Because there’s far more science possible with this dataset than we can do› Because IFS data is complicated, and we want to make it as easy as possible for

people to do science without being scared of the data9

Check out your favourite galaxy

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Look for weirdos

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Youngest early-type galaxy 618151

Highest SFR density609396

Most extended SF184648

Lowest mass slow rotator8391

Galaxies in context

› Identify a population of galaxies, e.g. centrally–concentrated SF (top) or strong winds (bottom)

› Select a sample from DR2› Comparison to large control

sample› Search wide parameter space for

other dependencies

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Outreach and education

› Easy to interact with interface and very visual data make SAMI an ideal dataset for classroom or undergraduate activities

› Exploring the Universe, galaxy treasure hunts, illustrations of fundamental physics, overview of galaxy evolution

› I would be very keen to hear your ideas on this!

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Questions?

›1559 diverse, representative galaxies›Cubes, stellar kinematics, stellar populations and much more

›Available from AAO Data Central on the 31st July