1 / 71

starlight.ufsc.br

Star formation & mass-assembly evolution of galaxies Fossil methods & applications to Mega data-sets. www.starlight.ufsc.br. – What do you mean “ fossil methods ”??. The 2 ways to study galaxy evolution. The time-machine method: Go back & find out how things were!.

mercedes-holman
Télécharger la présentation

starlight.ufsc.br

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Star formation & mass-assembly evolution of galaxiesFossil methods & applications to Mega data-sets www.starlight.ufsc.br

  2. – What do you mean “fossil methods”??

  3. The 2 ways to study galaxy evolution The time-machine method: Go back & find out how things were! G. Pal (1960) / H. G. Wells (1895)

  4. The 2 ways to study galaxy evolution The astronomical time-machine: redshift  time Cimatti 04 z =1.7! t • Get information directly from the past! • Compare properties of galaxies at different z’s • (CAVEAT: Not the same galaxy at different z’s, of course!!)

  5. The 2 ways to study galaxy evolution The fossil method:Retrace history of each galaxy SFH S SSPs

  6. The 2 ways to study galaxy evolution The fossil method: Example results SFH(t) of 1 Galaxy! M(t) / M(now) : Mass assembly history as a function of M* SFH(t) of the universe <Z*>(t) : Chemical Evolution x M* Panter 03, Heavens 04, ... Asari 07, CF 07, ...

  7. The rest of this talk: 1 – Fossil Methods / Inverse Population Synthesis: Decomposing galaxy spectra Basic concepts: Observables + Base + SFH Methods, methods, methods... 2 – Selected results / sanity checks / caveats & etc 3 – Amazing things you can do nowadays! The avalanche of information.... www.starlight.ufsc.br

  8. M1 + M2 + M3 + ... 1 – Fossil Methods: A quick tour SFH S SSPs

  9. M1 + M2 + M3 + ... Decomposing galaxy spectra: 3 Basic concepts Lgal(l) = SMSSP(t,Z)x SSP(l ; t,Z) t,Z Observables Full spectrum or Indices  Spectral Base Model or Observed SSPs / star-clusters Star Formation History + Chemical Evolution  How to derive it??

  10. Only 1 Z? Z = Z(t)? Al = ? Dust geometry? Al(t,Z)? Kinematics? Which base? (clusters, models,...) Which SFH parameters? Hypothese space (“priors”) Brute force discrete grid search? Convex-algebra? Markov-Chains? PCA? AI-techniques? Compression on input or output? Comparions to library of models? How to deal with degeneracies? Method Inverse Population Synthesis: How? Parameter space Observables space

  11. Inverse Population Synthesis: How? • Many methods! • STEllar Content via Maximum A Posteriori – Ocvirk 05, Koleva 07 • Active Instance-Based Machine Learning – Solorio 05 • Bayesian Latent Variable modelling – Nolan 06 • Principal Component Analysis – Li 05, Wild 07 • Direct fitting – Tadhunter 05, Moustakas 06, Chilingarian 07 • GASPEX, DINBAS2D – Mateu + Martinez + Magris • Brute Force – Bush 01, 02, 03, 04, 05, 06, 07, 08 • ... Huge diversity in: Math / elegance / speed 1000 “Technicalities” (masks, kinematics, extinction, ...) Physical ingredients Input & Output ...

  12. Evolutionary Synthesis: The High Resolution Era  Improvements in spectral librariesPredictions on ~ Å scales! Gonzalez Delgado 05 Le Borgne 04 Bruzual & Charlot 03

  13. The post-2003 boom in Full Spectral Synthesis Koleva 07: Fit globular clusters & find same t & Z as from CMD  OBS: rectified spectra = continuum-less

  14. Inverse Population Synthesis: Input • Observed spectrum • eg, a SF galaxy from the SDSS (B) Spectral Base eg, N >> 1 SSPs from BC03

  15. Inverse Population Synthesis: Output Observed spectrum + Base + Inversion method  SFH • (A) Observables: • - full spectrum • Nl~ 1000–4000 pixels • (B) Spectral base: • - N* = 25 x 6 = 150 (!) • SSP(l)’s from BC03 • (C) Inversion method: • - Markov Chains • exploration of • parameter space • (D) Tricks / Details: • - 1 extinction model • - kinematics: s* & v* • - 25 ages x 6 Z’s SFH

  16. 2 – Some Results, Sanity checks & etc

  17. Spectral Synthesis with MOPED Multiple Optimized Parameter Estimation and Data compression • (A) Observables: • - full spectrum compressed to Nl = 23 pixels... • (B) Spectral base: • - N* = 12 “finite bursts” • of different ages (BC03) • (C) Inversion method: • - Fit 23 parameters... • (D) Tricks / Details: • - 1 extinction model • - NO kinematics  • - Z = Z(t) = one Z per age SFH Panter 03, 07, Heavens 04 ...

  18. M* Mass assembly histories: M(t) Spectral Synthesis with MOPED • Compressed F(l) fits • Light (Mass) in N ~ 10 age bins & 1 Z for each age • Compress INPUT! Downsizing SFH of the Universe! Panter 07 Mathis 06

  19. Spectral Synthesis with STARLIGHT Full pixel-by-pixel F(l) fits - Light (Mass) in N ~ 50–150 SSPs - Compress OUTPUT! Downsizing M* M(t) & Z(t) of Star-Forming galaxies Pop. vector = SFH CF 05, 07, Mateus 06, Asari 07, Sodre 08

  20. Sanity checks: good news  SFR(Synt) ~ SFR(Ha) !!! Asari 07

  21. Sanity checks: problems & solutions! Residuals ~ witihin errors, but systematic! Ellipticals SF-galaxies a-bands not fitted in massive ellipticals ...  Paula will fix this! Hb–missfit with STELIB ...  MILES fixes this!

  22. What changes with the new spectral bases??? Ellipticals Refits using CB07 models (MILES + Martins libraries) 2003 2007 Residuals are smaller ie., spectral fits are better!! • SFHs are smoother • AV > 0 .... • Mean ages decrease a bit • <Z> increase a bit ... Jean Michel Gomes thesis... SF-galaxies 2007 2003

  23. 3 – Amazing things you can do nowadays A journey through the SDSS + STARLIGHT databases www.starlight.ufsc.br

  24. Physical Properties: Stellar Mass log M* HII < Sey 2 < LINERs log MO

  25. Physical Properties: Mean Age <log t*> HII < Sey 2 < LINERs log yr

  26. Cloning technology applied to galaxy evolution 1st experiments / preliminary results

  27. The fossil time machine

  28. Experiments in galaxy cloning

  29. Experiments in galaxy cloning

  30. www.starlight.ufsc.br

  31. Left-over slides...

  32. TWINS: Galaxies with the same SFH

  33. Compression: Smooth output SFH on scales of D log t ~ 0.5 – 1 dex

  34. The 2 ways to study galaxy evolution The astronomical time-machine: redshift  time z =1.7! t  Get information directly from the past! Compare properties of galaxies at different z’s (CAVEAT: Not the same galaxy at different z’s, of course!!)

  35. The 2 ways to study galaxy evolution The time-machine method: Example results Spectra of galaxies @ z ~ 1.7 The “Lilly-Madau plot” SFH(t) of the Universe Cimatti 04 Hopkins 05 + ...

  36. The 2 ways to study galaxy evolution The fossil method / paleontology of galaxies Observer Data: galaxy spectrum Inverse Population Synthesis Telescope SFH: Evolution  Dig information about the past from fossils found here & now!

  37. Sanity checks: good news  Ha / Hb As found by Calzetti et al 94 in detailed studies of nearby galaxies  CAVEAT: Treatement of dust is still too naive... AV (gas) ~ 2 AV (Stellar) CF 05

  38. The post-2003 boom in Full Spectral Synthesis Nolan 06 Walcher 06 Mayya 06

  39. Global Relations Z(gas) x Mass <Z*> x Z(gas) <t> x Z(gas) <t> x Z(gas) <Z*> x Z(gas) <Z*> & <t> x Mass M* Tremonti 04, Gallazzi 05, 06 The SEAGal’s

  40. Physical Properties: Stellar Mass log M* HII < Sey 2 < LINERs log MO

  41. Physical Properties: Mean Age <log t*> HII < Sey 2 < LINERs log yr

  42. Physical Properties: Metallicity <Z*> HII < Sey 2 < LINERs log ZO

  43. Physical Properties: a/Fe “a-enhancement” Sey 2 < LINERs DMg

  44. Physical Properties: AGN Power L[OIII] Sey 2 > LINERs log LO

More Related