M5 = NGC 5904 ( nearest “intermediate-metallicity” globular cluster
Metallicity: A Smoking Gun for Gas Flows in Mergers
description
Transcript of Metallicity: A Smoking Gun for Gas Flows in Mergers
Lisa Kewley - [email protected]
Lisa Kewley U. Hawaii
Margaret Geller (SAO), Betsy Barton (UC Irvine)
Lisa Kewley - [email protected]
MotivationMotivation
Metallicity diagnosticsMetallicity diagnostics
Luminosity-Metallicity RelationLuminosity-Metallicity Relation
Central Star FormationCentral Star Formation
Blue BulgesBlue Bulges
Merger ModelsMerger Models
Conclusions & Future WorkConclusions & Future Work
SummarySummary
Lisa Kewley - [email protected]
Effect of mergers
on metallicity?unknown
Predicted gas flows?elusive
Fabbiano et al. (2004)
MotivationMotivationFeSiMg
Lisa Kewley - [email protected]
502 galaxies from the CfA redshift catalog (v > 2300 km/s, v < 1035 km/s, D < 77 h-1 Mpc)
Nuclear spectra for ~200 galaxies in pairs (Barton et al. 2000)
Galaxy PairsGalaxy Pairs
198 galaxies from the CfA redshift catalog
full range in Hubble type & Magnitudes in CfA survey (Jansen et al. 2000) http://cfa-www.harvard.edu/~jansen/nfgs/nfgssample.html
Field GalaxiesField Galaxies
Lisa Kewley - [email protected]
Kewley & Dopita (2002, ApJS, 142, 35)
“R23”
Metallicity DiagnosticsMetallicity Diagnostics
Also: Pagel (1979), McCall et al. (1985), ...,Also: Pagel (1979), McCall et al. (1985), ...,Skillman et al. (1989), McGaugh (1991),...,Skillman et al. (1989), McGaugh (1991),...,Zaritsky et al. (1994), Charlot (2001), ...Zaritsky et al. (1994), Charlot (2001), ...
Lisa Kewley - [email protected]
Galaxy PairsGalaxy Pairs
Kewley, Geller, & Barton (2005, AJ, 131, 2004)
Luminosity-metallicity Relation
1. shifts for close pairs
Lisa Kewley - [email protected]
Kewley, Geller, & Barton (2006, AJ, 131, 2004)
Luminosity Effect?Luminosity Effect?
close pairs
wwide pairs
NFGScz < 2300 km/s
Need 1-2 Mag rise
Lisa Kewley - [email protected]
Kewley, Geller, & Barton (2006, AJ, 131, 2004)
Luminosity Effect?Luminosity Effect?
close pairs
wwide pairs
NFGScz < 2300 km/s
No shift in upperbound : MB
Negative shift in right bound: metallicity
Lisa Kewley - [email protected]
Luminosity Effect?Luminosity Effect?
Kewley, Geller, & Barton (2006, AJ, 131, 2004)
R-Band Luminosity-metallicity Relation
1. still shifts for close pairs
Lisa Kewley - [email protected]
Galaxy PairsGalaxy Pairs
Kewley, Geller, & Barton (2006, AJ, 131, 2004)
Luminosity-metallicity Relation
1. shifts for close pairs
metallicity effect?gas infall?
Lisa Kewley - [email protected]
Central Burst Strength, SCentral Burst Strength, SRR(t)(t)
Barton, Geller & Kenyon (2003):
Stellar population synthesis models + colors + EWsassuming 2 populations (old & young)
SR(t) = current fraction of R-band light from young burst
Lisa Kewley - [email protected]
Central Central Burst Burst
StrengthStrength
Barton, Geller & Kenyon (2003)
Lisa Kewley - [email protected]
Galaxy PairsGalaxy Pairs
Kewley, Geller, & Barton (2006, AJ, 131, 2004)
Luminosity-metallicity Relation
1. shifts for close pairs
2. correlated with central burst strength
Lisa Kewley - [email protected]
Galaxy PairsGalaxy Pairs
Kewley, Geller, & Barton (2006, AJ, 131, 2004)
Luminosity-metallicity Relation
1. shifts for close pairs
2. correlated with central burst strength
Lisa Kewley - [email protected]
Blue BulgesBlue Bulges
Kannappan et al. (2003): “blue bulge parameter”
(B-R) = (B-R)outer - (B-R)inner
where (B-R)outer = (B-R) at 75% light radius
(B-R)inner = (B-R) at 1/2 light radius
Lisa Kewley - [email protected]
Galaxy PairsGalaxy Pairs
Kewley, Geller, & Barton (2006, AJ, 131, 2004)
Luminosity-metallicity Relation
1. shifts for close pairs
2. correlated with central burst strength
3. correlated with blue bulges
Blue Bulges
Lisa Kewley - [email protected]
Metallicity GradientMetallicity Gradient
Kewley, Geller, & Barton (2005, AJ, submitted)
Keck LRIS Spectroscopy
Lisa Kewley - [email protected]
Metallicity GradientMetallicity Gradient
Kewley, Geller, & Barton (2005, AJ, submitted)
Keck LRIS Spectroscopy
See also:Li Hsin Chien’sPoster
Lisa Kewley - [email protected]
Galaxy PairsGalaxy Pairs
Kewley, Geller, & Barton (2006, AJ, 131, 2004)
Luminosity-metallicity Relation
1. shifts for close pairs
2. correlated with central burst strength
3. correlated with blue bulges
Evidence for Gas Infall
Lisa Kewley - [email protected]
Metallicity GradientsMetallicity Gradients
Lisa Kewley - [email protected]
Metallicity GradientsMetallicity Gradients
M101
Kennicutt, Bresolin & Garnett (2003)
Lisa Kewley - [email protected]
Merger ScenarioMerger Scenario
Iono et al. (2004): Simulations predict:
1. Gas inflow rate ~ 7 Mo/yr 2. Gas flows within 1st 100 Myr but before disk merger
.
Lisa Kewley - [email protected]
Merger ScenarioMerger Scenario
Iono et al. (2004): Simulations predict:
1. Gas inflow rate ~ 7 Mo/yr 2. Gas flow within 100 Myr but before disk merger
.
Lisa Kewley - [email protected]
Merger ScenarioMerger Scenario
Assuming:1. Gas inflow rate ~ 7 Mo/yr2. Normal Spiral Metallicity gradient
.
How much infalling gas is required?
Lisa Kewley - [email protected]
Merger ScenarioMerger Scenario
Assuming:1. Gas inflow rate ~ 7 Mo/yr2. Normal Spiral Metallicity gradient
.
How much central dilution is required? 50-60%
Merger models predict: 60% infall
Lisa Kewley - [email protected]
Merger ScenarioMerger Scenario
Assuming:1. Gas inflow rate ~ 7 Mo/yr2. Normal Spiral Metallicity gradient 3. Central Gas Mass 108 - 109 Mo ave v. high
.
How long will it take to infall?
.
Lisa Kewley - [email protected]
Merger ScenarioMerger Scenario
Assuming:1. Gas inflow rate ~ 7 Mo/yr2. Normal Spiral Metallicity gradient 3. Central Gas Mass 108 - 109 Mo
.
How long will it take to infall? 9x106 - 9x107 years
Merger models predict: within 1x108 years
.
Lisa Kewley - [email protected]
New Theoretical ModelsNew Theoretical Models
Josefa Perez et al. (2006, astro-ph/0605131)
Chemical evolution model (Scannappieco et al. 2005)
CDM model (GADGET-2; Springel & Hernquist 2003)
Lower mean central (O/H) in pairs from inflows
+
Lisa Kewley - [email protected]
Close galaxy pairs have lower than field Close galaxy pairs have lower than field central metallicitiescentral metallicities
““Smoking gun” Smoking gun” for gas infall during merger?for gas infall during merger?
Central metallicity correlates with: Central metallicity correlates with:
central burst strengthcentral burst strength blue bulgesblue bulges
Timescale consistent with current Timescale consistent with current merger simulationsmerger simulations
ConclusionsConclusions
Lisa Kewley - [email protected]
Keck LRIS spectra of matched pair membersKeck LRIS spectra of matched pair members
Merger simulations of metallicity gradientsMerger simulations of metallicity gradients
Future DirectionsFuture Directions
Lisa Kewley - [email protected]
Starburst99-Mappings On-LineStarburst99-Mappings On-LineL. Kewley & C. LeithererL. Kewley & C. Leitherer
Interactive web form to run modelsInteractive web form to run models
Pre-run model gridsPre-run model grids
Starburst99-Mappings Interface: http://www.stsci.edu/science/starburst99/
Mappings Interface: http://www.ifa.hawaii.edu/~kewley/Mappings
Lisa Kewley - [email protected]
Effect of mergers
on metallicityis unknown
Fabbiano et al. (2004)
MotivationMotivationFeSiMg
Lisa Kewley - [email protected]
Metallicity Diagnostic ComparisonsMetallicity Diagnostic Comparisons
Kewley & Ellison (2005)
Lisa Kewley - [email protected]
Metallicity: Metallicity: Strong lines vs Auroral LinesStrong lines vs Auroral Lines
Garnett, Kennicutt, Bresolin
Lisa Kewley - [email protected]
Classification Classification SchemeScheme
Lisa Kewley - [email protected]
Galaxy PairsGalaxy Pairs
Kewley, Geller, & Barton (2005, AJ, submitted)
Luminosity-metallicity Relation
1. shifts for close pairs
2. correlated with central burst strength
3. correlated with blue bulges
Evidence for Gas Infall
1’
Lisa Kewley - [email protected]
Kobulnicky & Kewley (2004, ApJ, 617,240)
GOODS Survey: 0.3 < z< 1 GOODS Survey: 0.3 < z< 1
Lisa Kewley - [email protected]
Metallicity DiagnosticsMetallicity Diagnostics
1.1. TheoreticalTheoretical - photoionization models - photoionization models e.g., McGaugh (1991), Kewley & Dopita (2002), e.g., McGaugh (1991), Kewley & Dopita (2002),
Tremonti et al. (2004)Tremonti et al. (2004)
2.2. EmpiricalEmpirical - fit to T - fit to Tee metallicities metallicities e.g., Pilyugin (2000), Pettini & Pagel (2004)e.g., Pilyugin (2000), Pettini & Pagel (2004)
CombinationCombination - fit to T - fit to Tee method + method + theoretical metallicitiestheoretical metallicities e.g., Denicolo, Terlevich & Terlevich (2002)e.g., Denicolo, Terlevich & Terlevich (2002)
Lisa Kewley - [email protected]
Metallicity - [OIII]/Hb,[NII]/HaMetallicity - [OIII]/Hb,[NII]/Ha
Pettini & Pagel (2004)
Lisa Kewley - [email protected]
Metallicity Metallicity Diagnostic Diagnostic
ComparisonsComparisons
Kewley & Ellison (2005, in prep)
Lisa Kewley - [email protected]
Metallicity: Metallicity: Strong lines vs Auroral LinesStrong lines vs Auroral Lines
Garnett, Kennicutt, Bresolin
Lisa Kewley - [email protected]
Kobulnicky & Kewley (2004, ApJ, 617, 240)
GOODS Survey: 0.3 < z< 1 GOODS Survey: 0.3 < z< 1
Lisa Kewley - [email protected]
Auroral Line SaturationAuroral Line Saturation
Stasinska (2002,2005)