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Bruce Partridge, Haverford College, USA Outline: - CMB studiesEtudes CMB - Radio TechniquesTechniques de.

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Présentation au sujet: "Bruce Partridge, Haverford College, USA Outline: - CMB studiesEtudes CMB - Radio TechniquesTechniques de."— Transcription de la présentation:

1 Bruce Partridge, Haverford College, USA Outline: - CMB studiesEtudes CMB - Radio TechniquesTechniques de la radioastronomie - Radio emission from galaxiesEmission radio des galaxies - Sample of contributions:Exemples de contributions: - Star formation rate - taux de formation detoiles -Co-evolution of galaxies & - co-évolution de galaxies et de leurs central Black Holes trous noirs What Radio Astronomy Can Tell us about Galaxy Formation (and the Evolution of Cosmic Structure) Ce que la Radioastronomie peut nous apprendre sur la Formation des Galaxies (et sur lEvolution de la Structure Cosmique

2 Studies of the Cosmic Microwave Background Radiation (Etudes du Fond Cosmique* )--the widest survey at the earliest time Provide values of crucial Fournit de valeurs des parametres cosmological parameters, cosmologique important, p.ex. H o, DM, b, n s, w Soon to come: reionization à venir: lhistoire complete de history at z ~6-10réionisation à z ~6-10 Determine amplitude of Détermine lamplitude de baryonic density perturbations perturbations de densité baryonique at z ~ 1000à z ~ 1000 Confirm basic linear theory Confirme la théorie linéaire de la of growth of cosmic structurecroissance en densité de la structure cosmique Direct link to observed LargeLieu direct avec la structure à grande scale Structure (LSS) échelle (LSS) (Eisenstein, ApJ 633,560, 2005) * Version française grâce å Koffi Anyinefa, Haverford College, et Jonathan Braine

3 CMB information is derived from measurements of (small) anisotropies in the temperature of the CMB: WMAP, ground-based work on smaller scales, and soon Planck Information CMB provient de mesures de (petites) anisotropies dans la température du CMB: WMAP, instruments au sol observant de plus petites échelles, et bientôt, Planck WMAP T/T ~ 10 -5

4 Among the findings: b from ratio of peaks & n s from modeling the power spectrum Parmi les résultats: b à partir des hauteurs des pics du spectre de puissance & n s à partir de la modelisation du spectre de puissance

5 Direct detection of ~1 o peak in galaxy corre- lation function (by Eisenstein et al., ApJ 663,560, 2005)

6 Example: New results on power spectrum on small scales Résultats nouveaux: le spectre du puissance à petite échelle (Dunkley et al., ArXiv: ) From Atacama Cosmology Telescope (ACT)

7 Atacama Cosmology Telescope (ACT)

8 Constraints on power spectrum of initial density fluctuations…..and on 8 : ACT + WMAP7 give 8 = (Sehgal et al. 2010) SPT gives 8 = (Lueker et al. 2009), based on S-Z signals.

9 A potential surprise: CMB + He abundance imply >3 lepton families (see Oct. Physics Today for discussion of contested high energy physics). Une surprise: plus de 3 espèces de lepton

10 Relevant (?) By-Products of CMB Research Planck will produce detailed FIR & sub-mm SEDs of local galaxies (and hence constrain dust properties, particularly cold & anomalous dust) Planck will refine estimates of Cosmic Infrared Background ACT & SPT can define bright end of SMG counts & luminosity function (to date,radio sources dom- inate counts)

11 Recent work with Anna Sajina -- extrapolating from 22 & 43 GHz observations to 148 GHz: more evidence for non-AGN contributions to source counts below ~30 mJy

12 Radio Astronomical Techniques -Very high angular resolutionTrès grande résolution angulaire VLBI < arcsec -Ability to measure gas dynamicsMesure la dynamique du gaz (using 21 cm line): see talks by (utilisant la raie a 21 cm); voir de Blok, van Gorkum…. -Gas temperature & density Température du gaz et diagnostiques diagnostics (using, e.g., CO lines): de densité & dynamique (utilisant p.ex. see talks by Combes, Bureau …les raies CO); voir Combes, Bureau -Redshifts of optically obscuredDécalage vers le rouge z de galaxies galaxies (radio/FIR ratio & CO lines);obscurcies optiquement; voir see Carilli &Yun, ApJ 513 L13 (1999) & talks by Françoise Combes & Martin Bureau - ALMA will make major advances ALMA fera de grands progrès

13 Contributions of Continuum Radio Observations to the Understanding of Galaxy Evolution Two general modes of radio Deux modes demission continuum and submillimeter continuum radio et sub-milimetrique emission from galaxies: 1.) extended synchrotron, 1.) Rayonnement synchrotron, Brems. Bremstrahlung and dust & emission thermique de re-emission la pousssiere, associé à la formation associated with star formation stellaire à grand échelle 2.) AGN powered emission 2.) Rayonnement lié à lAGN central -dominated by synchrotron - synchrotron -complex morphology - morphologie compliquée Latter is much more luminous; No 2 est plus lumineux; donc le titre hence the title radio galaxies radio galaxies

14 Examples of radio emission from ordinary galaxies Quiescent Star-forming Passive M81 M82

15 Versus AGN, powered by a central Black Hole

16 Ordinary (Not AGN) Galaxies in the Radio A crucial and slightly mysterious linear correlation between FIR and radio luminosity (Helou et al., ApJ 298, L7, 1985) -Allows us to use radio as proxy for FIR emission, and thus star formation rate (SFR) (Condon, ARAA,1992) (Haarsma et al., ApJ 544, 641, 2000) -Avoids the need to correct for dust absorption -But does require correction for AGN -Depends on assumption that above correlation holds independent of redshift, z -Correlation itself implies that IMF is independent of galaxy luminosity (and therefore mass) and largely independent of z Une correlation lineaire critique mais pas tout á fait comprise entre lémission IR lointain (FIR) et radio (Helou et al., ApJ 298, L7, 1985) -Nous permet dutiliser l émission radio á la place du FIR afin destimer le taux de formation stellaire (SFR) -(Condon, ARAA, 1992) (Haarsma et al., ApJ 544, 641, 2000) -Evite le besoin de corriger pour lextinction par la poussière -Necessite une correction pour un eventuel noyau actif (AGN) -D é pend de lhypothèse que cette correlation est ind é pendent du redshift, z -Correlation implique que lIMF est ind é pendent de la luminosit é (donc de la masse) et largement ind é pendent de z.

17 (from Ivison et al., astro-ph/ ) L IR = 10 q L rad Note: q is independent of redshift z -- and holds for wide range of luminosity

18 SFR(z) from radio data alone (from blind radio surveys) SFR(z) déterminé de radio seulement (should be done again with newer data) (on doit répéter avec des observations récentes) -- a good student project

19 SFR from radio is somewhat higher than (these early) results from optical. Evidence for evolution of radio/FIR relation, or incomplete correction for AGN, or are optical estimates too low?

20 Constraints on Top End of IMF Several allusions to a possible top-heavy IMF at large z. Could alter radio/FIR relation: -- FIR measures total stellar energy output -- radio measures cosmic ray energy, and hence SNe (so stellar masses 8 M o ) Need to model the effect of a changed IMF (a good student project) Complications: -- cosmic ray escape (lowers radio) -- inverse Compton energy loss on CMB (lowers radio) -- incomplete conversion of stellar light to FIR (lowers FIR) Comment -- given the complications, remarkable that radio/FIR is so constant.

21 A Second Relation Connects mass of central Black Hole to mass of halo (or better the velocity dispersion,, in km/sec ) -- M BH ~ ( /200) ~4 Magorrian et al, 1998 Gebhardt et al Ferrarese & Merritt 2000 Is the log-log relation linear? Are there exceptions/deviations at the high mass end (see e.g. Lauer et al., and poster by Hlavacek-Larrondo )?

22 AGN and the Issue of Orientation Radio properties of AGN depend strongly on orientation of jet. Hence radio properties a poor diagnostic of properties of central Black Hole.

23 Speculative last slide: 5 questions. 1.Heresy: Did all Early type galaxies form the same way, by mergers? 2.Heresy: Could some E galaxies form monolithically; a single, early burst of star formation? ( as suggested by Eggen, Lynden-Bell & Sandage, 1962; Peebles & Partridge, 1967 ) 3.If so, would the relation between halo mass and central Black Hole mass be different in such galaxies? 4.Are there exceptions to the Black Hole/velocity correlation? 5.And could radio (or other) observations detect that difference?

24 Notice Avertissement The Astronomical Society of the Pacific (http://www.astrosociety.org)http://www.astrosociety.org On y trouve beaucoup de materiaux pour educateurs Offers a wide range of educational material -- in English and Spanish Would love to have some translated into French Nous avons besoin des versions françaises

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