Post on 01-Apr-2015
Crete, 1/24
Mapping the kinematics and stellar Mapping the kinematics and stellar populations populations
of E/S0s with SAURON of E/S0s with SAURON
Harald KuntschnerHarald KuntschnerCrete, 12Crete, 12thth August 2004 August 2004
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OutlineOutline
• Introduction• The SAURON survey• Results from
– Kinematics – Stellar populations with focus on
environmental effects
• Conclusions
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The SAURON teamThe SAURON team
PIs: Bacon, Davies, de Zeeuw
COIs: Bureau, Cappellari, Emsellem, Falcón-Barroso, Krajnović, Kuntschner, McDermid, Peletier
plus associated members …
http://www.strw.leidenuniv.nl/sauron
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GalaxyGalaxyformationformation
• When and how do E/S0/Sa galaxies form?– What is the orbital make-up of E/S0s?– What is the average age and metal
content?– Origin of substructures; e.g. faint disks
in Es, decoupled cores, etc.– E S0 Sa transformations?– What is the relationship between global
properties and super-massive black holes ?
SAURON
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The SAURON projectThe SAURON project
• Systematic study of a representative sample of 48 nearby E/S0s and 24 Sa-type spirals – Wide field integral-field spectroscopy from
the ground (SAURON)– Central high spatial sampling integral-field
spectroscopy with OASIS/GMOS – HST imaging (and some STIS spectroscopy)– Large scale ground based imaging
de Zeeuw et al, 2002, MNRAS, 329, 513
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The sample selectionThe sample selection
• Uniformly covering the ellipticity vs MB plane• MB -18 mag (factor of 50 in luminosity)• 24 E, 24 S0, 24 Sa (each 12 cluster, 12 field)• cz < 3000 km/s• DEC: -6° < d < +64° and |b| 15°
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Why integral-field Why integral-field spectroscopy?spectroscopy?
Galaxy Image
Velocity field
Velocity curve
Integral field
Long slit
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Status of the SAURON surveyStatus of the SAURON survey
• Observations completed in April 2002– 8 runs on William Herschel Telescope (4m)– 35.5/56 clear nights
• ~200.000 independent galaxy spectra • All data homogeneously reduced• Analysis and interpretation ongoing
– 5 refereed papers in 2004 so far
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48 E/S0 – DSS images 48 E/S0 – DSS images Emsellem et al., 2004, MNRAS, 352, 721
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SAURON-classified rotatorsSAURON-classified rotators
S0
S0 S0
S0
S0 E
E
EE
E
E E
S0 S0
S0
S0
S0 S0 S0
S0
E
S0S0
S0
S0
S0
E S0
E
E S0
E E
S0
S0
S0
40% classified by RC3 as ellipticals
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SAURON-classified ellipticalsSAURON-classified ellipticals
EE
E
E
S0 E
EE
EE
E
E
General agreement with RC3
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Results from the kinematic mapsResults from the kinematic maps
• Two classes of early-type galaxies – Flattened rotating lenticulars (some with bars)– Triaxial ellipticals (many kinematically
decoupled components)
• Discontinuous transition
NGC 4660 NGC 4458
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Line-strength: Age, Z, [Mg/Fe]Line-strength: Age, Z, [Mg/Fe]
• Wavelength covers H, Fe5015, [OIII], Mgb & Fe5270• Lick/IDS index definitions (+ SAURON adjustments)• Indices + Models can be used to estimate luminosity
weighted age, Z and abundance ratios.
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Kinematics and line-StrengthsKinematics and line-Strengths
I
V
Mgb
Fe
NGC 4546 NGC 4570 NGC 4406 NGC 4365NGC 4660 NGC 4382 NGC 4374
N
E
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Stellar population modelsStellar population models
Vazdekis (1999) models atLick resolution (~8.4 Å FWHM) based on Jones (1999) library
[MgFe52]=(Mgb x Fe5270)^0.5
Goal:
Estimate the luminosity weighted age, metallicity and abundance ratios.
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Central Re/8 measurementsCentral Re/8 measurements
Traditional RC3morphologies
Mostly old Es
Weak evidence for young stellar populations in some field Es
S0s in all environs spread to younger ages
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Central Re/8 measurementsCentral Re/8 measurements
New “morphologies”based on 2-dim kinematics
7 triaxial Es in field
only 4 triaxial Es in cluster
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NGC 5198 (E; field)NGC 5198 (E; field)V Hβ [MgFe50]
Age map Z map
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NGC 4150 (S0; cluster)NGC 4150 (S0; cluster)V Hβ [MgFe50]
Age map Z map
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NGC 4570 (S0; cluster)NGC 4570 (S0; cluster)V Hβ [MgFe50]
Age map Z map
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A bar in NGC 4570A bar in NGC 4570van den Bosch & Emsellem van den Bosch & Emsellem
(1998)(1998)Metal lines
Age map
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NGC 4382 (S0; cluster)NGC 4382 (S0; cluster)V Hβ [MgFe50]
Age map Z map
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Statistics – young Statistics – young populationspopulations
• 19/48 (40%) of our sample show some evidence of “young” (<10Gyr) stellar populations in the central regions
• E cluster: 1/12• E field: 4/12 E total: 5/24
• S0 cluster: 7/12• S0 field: 7/12 S0 total:
14/24
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ConclusionsConclusions• SAURON provides 2-dim kinematics and line-strength for
48 nearby E/S0• Kinematics
– Many RC3 classified Es show strong rotation; we suggest new classification in triaxial Es and rotators
• Line-strength – Connection between ‘disk-like’ kinematics and
enhanced Mgb line-strength (not seen so clearly in Fe lines!)
– Evidence for secular, bar-driven evolution in S0s young pops rotation connection in some galaxies
– As many as 40% of E/S0 galaxies show signs of young stellar populations mostly in the central regions
• Only weak evidence for environmental effects in our sample