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1
Paleontology of Galaxies Recovering Star Formation & Chemical
Enrichment Histories from galaxy spectra
Roberto Cid FernandesUFSC – Florianópolis -Brasil
2
STARLIGHT & its many applications
Spectral fits & star-formation histories
Asari et al 2006CF et al 2005CF et al 2004
5
STARLIGHT & its many applications
HE0450-2958 – The “homeless” QSO
CaII Triplet velocity dispersions
Vega 2004, Garcia-Rissman et al 2005
Merritt et al 2006
8
The team(s)• Techniques: L Sodré, J Gomes, Merlin, Harry Potter, ...
• Seyfert 2s: Q Gu, J Melnick, E & R Terlevich, D Kunth
• LLAGN: R González Delgado, E Pérez, H Schmitt, L Martins, T Storchi-Bergmann
• SDSS: A Mateus, L Sodré, G Stasinska, J Gomes, N Asari, W Schoenell, L Vega, J P Papaqui
• Ca-Triplet: L Vega, N Asari, A Garcia-Rissman,...
• WR-galaxies: J Leão, C Leitherer
• UCBD-galaxies: M Corbin, W Vacca, ...
• The homeless QSO: D Merrit, T Storchi-Bergmann, D Axon, ...
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The talk1- STARLIGHT: Spectral fits using evolutionary synthesis models
How? What it can(’t) do for you
Miscelaneous Applications: 2 - Seyfert 2s3 - Low Luminosity AGN4 - CaT-synthesis5 - UCBDGs
6 - SDSS: Fits for 582471 galaxies! Mass, age, Z*, *, ...
Correlations, correlations & correlations...Star-Formation & Chemical enrichment Histories ...
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The Conclusions1 STARLIGHT: It works!!
Recovers M*, <t*>, <Z*>, *, AV, ... And pretty decent SF & chemical histories too!
2 Seyfert 2s: Heterogeneous Star-Formation history Fits uncover reflected AGN! (BLR + continuum)
3 LLAGN: LINERS are all OLD & boring Transition Objects = OLD or “YOUNG” Young-TOs are dusty 108–109 yr post-starbursts
...
6 SDSS: Beautiful results, but too much info to digest!!!
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Spectral synthesis ofintegrated stellar
populations:
“...a subject with bad reputation. Too much has been claimed, and too few have been persuaded.”
(Searle, 1986)
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1 – STARLIGHT: The ingredients
• 150 SSPs from Bruzual & Charlot (2003)25 ages: t = 1 Mr – 18 Gyr6 metallicites: 0.005 – 2.5 Zo
• 1 Reddening law (Cardelli/Calzetti/LMC/SMC)
• 1 Gaussian LOSVD: G(v*,*)
• 2 or 3 smart collaborators/students
• lots of CPUs ... (~ 150 for ~ 6 months!)
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1 – STARLIGHT: The parameters
x = x(t,Z) = light FRACTION at from population t,Z
= “population vector”
= (x1,x2,...xN) = Star Formation History
Other parameters:
AV = dust (only 1 so far...) v* = “redshift”
* = velocity dispersion
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1 – STARLIGHT: The nuts & bolts
+ Movies!08 , 32 , 39
• Data: O ± ; = 3400 – 8900 Ǻ – observed spectrum
• Model: M(x,AV,v*,*) – model spectrum = SSPs
• Problem: How to estimate x1...xN, AV, v* e *?~ 150 + 3 = 153 parameters!
• Method: Markov Chain Monte CarloMetropolis-Hastings + Simulated-annealingLikelyhood guided “quasi-random” walk
Prob(x,AV,v*,*| Data) ~ exp –{2 / 2}
2 = {O – M(x,AV,v*,*)}2
2
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1 – STARLIGHT: The future
+ Public version by 2006.9999 (code + SDSS fits)
+ 2006.9: -enhanced SSPs – essential for Ellipticals! (Coelho et al, …) ... Not so easy...
+ 2005.5: Nebular continuum .... Done
+ 2005.9: More than 1 extinction ... Done, but ...
+ 3001.2: Smarter/faster method to explore huge parameter spaces
(adaptative-MCMC, Genetic-MCMC, …)
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CF, Gu, Melnick, Terlevich2, Kunth, Rodrigues Lacerda, Joguet 2004, MNRAS
2 – The SF-History of Sey 2 nuclei
• 79 galaxies 65 Sey 2s
• ~ 200 pc
• Base = BC03 + FC
Strong FC in this Sey
1
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Result #1: SFH of Sey 2s is very heterogenous!
Continuous SF
InstantaneousBursts
Power-Law + E-gal
“Broad Line Sey 2s”
or “Sey 3s”
?!
23
Result #2: Weak (scattered) BLR & FC!
• Starlight-subtracted spectra reveal weak broad H in 10/65 Seyfert 2s!
• Most of these have Hidden BLRs revealed in polarized spectra (Tran 95, 01)
• Spectral synthesis finds a strong FC component (~ 20%) in these “Broad Line Seyfert 2s”
Conclusion: Scattered light!
24
• Long-slit spec. of ~ 50 LLAGN
• Spatial Resolution ~ 1” ~ 100 pc
• Spectral synthesis of 521 extractions
• Base of template galaxies representing Y, I & O populations
St pop, extinction & brightness profiles
3 – LINERs & TOs
CF + Gonzalez Delgado et al 2004, 2005Gonzalez Delgado + CF et al 2004
26
2 + 3 = Evolution of (stars in) AGN?
<t*(Sey2)> < <t*(Young-TO)> < <t*(Old-TO)> = <t*(LINER)>
<t*(Starburst)> < <t*(Young-TO)> < <t*(Old-TO)>
To be continued....
27
4 – Calcium Triplet work
A Garcia Rissman (LNA), L Vega (Córdoba/UFSC), N Vale Asari (UFSC), CF, H Schmit (NRL),
R González Delgado (IAA), T Storchi-Bergmann (UFRGS)
Garcia-Rissman et al 2005, MNRAS+ Vega et al 2006 (in prep)
+ Barbosa et al 2006 (IFU => v-field)
Different application of the same code: *
28
4 – Calcium Triplet work Garcia-Rissman et al 2005
Fits with a base of observed stars (kinematical templates) plus a fake continuum
30
5 – Ultra Compact Blue Dwarf galaxies
Corbin et al 2006
Fits with:
- 25 ages- Z0/50 SSPs- SMC ext curve- Nebular Cont.
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5 – Ultra Compact Blue Dwarf galaxies
Corbin et al 2006
age
Light dominated by young stars
But most mass is in old generations
NOT primaeval!
32
6 – Synthesis of 582k SDSS galaxies
N Asari, J Gomes, W Schoenell, J P Papaqui (UFSC)A Mateus (IAG), L Sodré (IAG) & G Stasinska (Meudon)
The SEAGal Collaboration: Semi-Empirical Analysis of Galaxies
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6 – Synthesis of 350k SDSS galaxies
A journey through the fascinating (but scary) world of Mega Data Bases
34
Products of the synthesis x = x(t,Z) : Star-formation & chemical histories M* : stellar Mass
t* & Z* : mean stellar age & stellar metallicity
* : velocity dispersion
AV : extinction
Observed – Model F() = pure emission spectrum Emission line fluxes Nebular metallicity, extinction, ...
6 – SDSS: 1st results (CF et al 05, MNRAS)
35
Stellar versus nebular extinction
AV (Balmer) = 0.3 + 1.8 AV (Stellar)
Normal Emission Line Galaxies
(= non-AGN)
39
Stellar X nebular metallicity!
Normal Star Forming Galaxies (= non-AGN)
• Very interesting prospects for chemical
evolution studies ...
• Confirmed, but NOT cited, by a recent paper
in MNRAS
40
Stellar age x stellar mass
More massive galaxies are older.
“Downsizing”
“Anti-Hierarchical” scenario
too old too faint ...
42
Going one step further: SFHsIdea:
Dissect the SFH = SFR(t) along the left wing of the Seagull (normal SF galaxies)
angle ~ Z(gas)
44
Going one step furtherSmall, ~ HII galaxiesDominated by ~ 1 burst
Big, ~ Starburst nucleiMixture of bursts
mea
n ag
e
46
6 – SDSS: bottomline
Too much information!
Parameter
But great results!! Can’t be too wrong!
brigad!!
?
48
A nagging question: Which base?Results change if one allows for Z < 0.2 Z0 populations in the base!
• 1/5 < Z < 2.5
• 1/200 < Z < 2.5
49
HE0450-2958
Merritt et al 2006
The “homeless” QSO – not homeless!
ULIRG companion galaxy
100 Myr burst ~ interaction age
But not homeless afterall...Just a NLSy1 with a wrongly calculated Black Hole mass!
QSO
star
Magain et al 2005
51
5 – Ultra Compact Blue Dwarf galaxies
Corbin et al 2006
Fits with:
- 25 ages- Z0/50 SSPs- SMC ext curve- Nebular Cont.
52
Coarse (but robust) description of the st pop
INTERMEDIATE108-9 yr
OLD 1010 yr
YOUNG (+ FC)106–7 yr
• Population vector:
Reduce x from N* ~ 45 => 3 components
x = (xY,xI,xO)
xY+ xI+ xO = 1 plane
CF et al 01, 03, 04, GD et al 04
53
Result #1: SFH of Sey 2s is very heterogenous!
• Population Vector:
x = flux-fractionx = ( Y+FC , I , O )
Y/FC = 5 Myr + -1.5 FC
I = 100 Myr – 1 Gyr
O = 1 – 10 Gyr
Old pop + burst
54
Result #1: SFH of Sey 2s is very heterogenous!
~ 40% Starburst
+ Seyfert 2
composites
“pure/boring” Seyfert 2
55
WK
X [OI]/H
3 – LINERs & Transition Objects
OldYoung
Young TOs OldTOs
OldLINERs
Young LINERs
AG
N
CF et al 04, 05GD et al 04, 06
...
56
• Long-slit spec. of ~ 50 LLAGN
• Spatial Resolution ~ 1” ~ 100 pc
• Spectral synthesis of 521 extractions
• Base of template galaxies representing Y, I & O populations
St pop, extinction & brightness profiles
3 – LINERs & TOs
59
• Young-TOs have much more dust than
Old-TOs or Old-LINERs
Young-TOs
Old-TOs &
LINERs
3 – Dust in LLAGN: AV(r)
60
• Young-TOs have much more dust than
Old-TOs or Old-LINERs
• Central 108-9 yr population is compact
R ≤ 100 pc
• M* ~ 107 Mo
Young-TOs
Old-TOs &
LINERs
3 – Dust & St pops in LLAGN
61
2 + 3 = Evolution of (stars in) AGN?
<t*(Sey2)> < <t*(Young-TO)> < <t*(Old-TO)> = <t*(LINER)>
<t*(Starburst)> < <t*(Young-TO)> < <t*(Old-TO)>
To be continued....