1 / 20

Old Massive Galaxies in the Early Universe tell better Stories about Reionization

Old Massive Galaxies in the Early Universe tell better Stories about Reionization. Nino Panagia (STScI, INAF, SN Ltd). Mostly based on work done in collaboration with: (in inverse alphabetical order ) Tommy Wiklind Massimo Stiavelli Bahram Mobasher Mike Fall Et Al.

mckile
Download Presentation

Old Massive Galaxies in the Early Universe tell better Stories about Reionization

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. Old Massive Galaxies in the Early Universe tell better Stories about Reionization Nino Panagia (STScI, INAF, SN Ltd) The End of the Dark Ages

  2. Mostly based on work done in collaboration with: (in inverse alphabetical order) Tommy Wiklind Massimo Stiavelli Bahram Mobasher Mike Fall Et Al. The End of the Dark Ages

  3. We know that the Universe is not quite ionized at redshift z=6.28 Becker et al. (2001) The End of the Dark Ages

  4. Becker et al (2001):The full story The End of the Dark Ages

  5. • Reionization requires sources of Lyman continuum photons • Reionization depends primarily on the UV output of the RI sources integrated over time • Reionization is a function of the UV photon escape fraction, f, from the RI sources and the clumpiness of the IGM <Q> = <MHI> ×f –1 × B(z1,z2,C) The Principles of Reionization (RI) escape fraction Ly-c photons HI mass = HI×Volume photons needed per ionization The End of the Dark Ages

  6. The effect of the IGM clumping on Reionization[Stiavelli, Fall & Panagia 2004a] Effective number of photons to ionize an atom Clumping factor C = <n2H>/<nH>2 The End of the Dark Ages

  7. Recognizing the Reionization Agents • (Young Bright) Galaxies at z>6.5 are doing it • (Evolved Massive) Galaxies at z<6.5 have done it • Together they define the process of Reionization The End of the Dark Ages

  8. Reionization constraintsfrom HUDF observations Stiavelli, Fall & Panagia (2004b) T=100,000K (Z=0) T=50,000K (Z=Z/100) The galaxies that may be ionizing NOW… 32 30 28 26 24 32 30 28 26 24 mAB(rest=1400Å) The blue line refers to UDF objects selected by i-z>2, the red one to i-z>1.3.

  9. HUDF-JD2, a Balmer Break Galaxy prototypeA galaxy that did it in the past?[Mobasher et al. 2005] Rest-frame [m] 0.1 0.2 0.4 0.8 z = 6.5 M = 61011 M z=2.5-3.4 0.5 1 2 5 10 Observed  [m] The End of the Dark Ages

  10. Properties of HUDF-JD2[Mobasher et al 2005, Panagia et al 2005] Massive M/M  = 6 × 1011 Bright L/L = 1012 Evolved Age > 350-650 Myr zform > 9 Ionizing Q ~ 4 × 1072 Ly-c photons The End of the Dark Ages

  11. HUDF-JD2:An Old Galaxy that did a LOT Model including chemical evolution [Panagia et al 2005] eff: Ratio of the time averaged Lyman continuum photon flux to the present UV flux Age The End of the Dark Ages

  12. HUDF-JD2 Enough to re-ionize its region of Universe? By itself only if high escape fraction and low clumping companions dereddened Easily if invisible companions with a reasonable LF are present Panagia et al. 2005 The End of the Dark Ages

  13. HUDF-JD2: A summary • Massive, luminous, protypical Balmer-break galaxy • It has had an important impact (>20%) on the reionization of the IGM starting a z~15 • With the “help” of fainter companions distributed according to an  =1.6 Schechter LF it may account for the whole effect The End of the Dark Ages

  14. Is HUDF-JD2 unique? • Tommy Wiklind answered this question: “not quite” • Actually, combining deep HST and Spitzer multi-band photometry one finds about one bright BBG per 10 square-arcmin field The End of the Dark Ages

  15. Re-Ionization Balance - I • UV output from BBGs in the Chandra Deep Field South Qtot= 4.2 × 1073 fLyman-continuum photons • H-atoms in a volume in the redshift interval 7-15 NH = 1.2 × 1073atoms • If the detected BBGs are the only UV sources in the field B/f = 3.5 The End of the Dark Ages

  16. The effect of the IGM clumping on Reionization[Stiavelli, Fall & Panagia 2004a] Effective number of photons to ionize an atom Clumping factor C = <n2H>/<nH>2 The End of the Dark Ages

  17. Re-Ionization Balance - II • With a clumping C > 10  B > 2 f > 0.6 unlikely!? • The IMF may be top-heavy too easy!!! • Additional, fainter, undetected galaxies contribute to the reionization possible • In this case, with C>10 and f<0.2, the fainter companions should provide an additional ~200% of ionizing radiation. • This corresponds to a Schechter luminosity function steeper than =1.3 quite reasonable • Detecting and studying the fainter companions is not easy with current telescopes but it will feasible with JWST. The End of the Dark Ages

  18. Conclusions Hubble Ultra Deep Field “Dark Ages” Hubble Deep Field primordial galaxy end of reionization Here Now S1 Big Bang HST JWST recombination normal galaxy H I H II z ~ ∞ z ~ 6-10 TIGM~ 4z K TIGM~ 104 K z ~ 103 t z The End of the Dark Ages

  19. Conclusions • Balmer-Break Galaxies (BBG) are importantfor the reionization of the IGMstarting at z~15or higher • With the help of fainter companions they have the potential of ionizing the IGM entirely • JWSTis needed to detect and study the population of “reionizers” The End of the Dark Ages

  20. THE END The End of the Dark Ages

More Related