Spectroscopy of Blue Supergiants in the Disks of Spiral Galaxies: Metallicities and Distances. Rolf Kudritzki

Transcription

1 Spectroscopy of Blue Supergiants in the Disks of Spiral Galaxies: Metallicities and Distances Rolf Kudritzki

2 ΛCDM-universe metallicity of galaxies depends on their mass Extragalactic stellar astronomy metal-rich metal-medium metal-poor M81 NGC 300 WLM

3 Lequeux et al., 1979, A&A 80, 155 Extragalactic stellar astronomy the pioneering paper data from HII regions using strong line methods

4 Tremonti et al., 2004, ApJ 613, 898 Extragalactic stellar astronomy strong nebular emission lines: hydrogen, oxygen, nitrogen 50,000 starforming galaxies with Sloan spectra

5 mass-metallicity relationship Extragalactic stellar astronomy Rosetta stone to understand galaxy formation and chemical evolution! Tremonti et al., 2004, ApJ 613, 898

6 mass-metallicity relationship Extragalactic stellar astronomy However Something must be wrong. MW It s based on very simplified emission line analysis. SMC LMC Tremonti et al., 2004, ApJ 613, 898

7 strong line method: R 23 = f[n(o)/n(h)] simple empirical calibration but R 23 depends on T electron n electron nature of ionizing stars gas imhomog. filling factors depletion into dust.. Pagel, Edmunds, Blackwell et al. 1979

8 Extragalactic SDSS star stellar astronomy forming galaxies 0.9 dex!!! Kewley & Ellison 2008 mass metallicity relationship depends crucially on strong line method calibration supergiant stars will come to rescue!!!!

9 supergiants objects in transition Brightest normal stars at visual light: L sun -7 M V -10 mag B1 A4 t ev ~ 10 3 yrs L, M ~ const. ideal to determine chemical compos. abundance grad. SF history extinction extinction laws distances of galaxies

10 nearby supergiants in Orion 1000 Lyrs away Rigel

11 Heidelberg, FORS transport Goettingen & to Munich P. astronomers on the way to Paranal FORS 1

12 pilot study NGC 300 Sculptor 70 blue Group supergiant (2 Mpc) spectra Kudritzki, Urbaneja, Bresolin et al. 2008, ApJ 681, 269

13 Study of metallicities

14 [Z] =

15 Spectral window Å

16 Spectral window Å

17 χ i spectral window Å

18 Χ i all windows [Z] = -0.4±0.1

19 Stellar metallicity gradient in NGC300 B0 B3 supergiants B8 A4 supergiants --- log{z/z_sun} = ρ/ρ 0 = d/kpc Kudritzki, Urbaneja, Bresolin, Przybilla, Gieren, Pietrzynski, 2008, ApJ 681, 269 angular galactocentric distance ρ 0 = 9.75 arcmin 5.7kpc

20 Extragalactic Stellar Spectroscopy Stellar vs. HII metallicity gradient Who is right??? ---- Zaritsky Dopita Kobolnicky Denicolo Pilyugin Pettini &Evans et (2001) Pagel et et al. (1994) al. (2002) (2004) (1986) (1999) Almost identical with stellar regression!!!! Kudritzki et al., 2008, ApJ 681, 265 Extragalactic Pizza IfA March 1st

21 The solution? Auroral lines!! nebular lines auroral line

22 strong lines and auroral lines auroral line strong lines Bresolin, 2009

23 VLT/FORS2 NGC 300 Bresolin, Gieren, Kudritzki, Pietrzynsky, Urbaneja & Carraro 2009, ApJ, 700, auroral line detections (previously: 2)

24

25

26 Bresolin,Gieren, Kudritzki et al HII- auroral * supergiants supergiants regression HII-auroral lines regression Excellent agreement between auroral lines and supergiants!!

27 Auroral lines vs. strong lines calibrations a horror story!! this work McGaugh91 Tremonti et al Kewley/Dopita 2002 Pettini/Pagel 2004 Bresolin,Gieren, Kudritzki et al. 2009

28 Bresolin, Gieren, Kudritzki, Pietrzynsky, Urbaneja & Carraro 2009, ApJ, 700, 309 NGC dex

29 M81 Keck LRIS Kudritzki, Urbaneja, Gazak et al., 2012, ApJ 747, 15

30 M81 object C20 Kudritzki, Urbaneja, Gazak et al., 2012, ApJ 747, 15

31 super solar [Z] M81 very shallow gradient: 0.03 dex/kpc Kudritzki, Urbaneja, Gazak et al., 2012, ApJ 747, 15

32 PNe, Stanghellini et al BSG, this work Strong chemical evolution over last 5 Gyrs Kudritzki, Urbaneja, Gazak et al., 2012, ApJ 747, 15

33 A mass-metallicity relationship only from stellar spectroscopy Kudritzki, Urbaneja, Gazak et al., 2012, ApJ 747, 15

34 Comparison with HII strong line methods (Kewley & Ellison, 2008) Kudritzki, Urbaneja, Gazak et al., 2012, ApJ 747, 15

35 trust the stars.

36 H 0 uncertainty and universe equation of state Hubble constant uncertainty EoS parameter w despite enormous effort still: δh 0 ~ 10% δw ~ 0.2 compare Freedman et al., 2001 Saha et al., 2001, Sandage et al., 2006 Mould & Sakai, 2008, 2009ab Riess et al., 2009, 2011, 2012 δh 0 ~ 3%

37 The perennial problem of extragalactic distances Extragalactic stellar astronomy patchy dust extinction metal-poor metallicity dependence of distance indicators metal-rich

38 IoA 2011 Flux weighted Gravity Luminosity Relationship (FGLR) Kudritzki, Bresolin, Przybilla, ApJ Letters, 582, L83 (2003) L,M ~ const. B1-A4 M~ g R 2 ~ L (g/t 4 ) = const. const. with L ~ M x ~ L x (g/t 4 ) x, x ~ 3 L 1-x ~ (g/t 4 ) x or with M bol ~ -2.5log L M bol = a log(g/t 4 ) + b FGLR a =2.5 x/(1-x) ~ 3.75

39 Kudritzki, Urbaneja, Bresolin et al., 2008, ApJ 681, 269 M bol = 3.41{ log(g/t 4 eff,4 ) -1.5} 8.02 σ = 0.32 mag

40 A supergiant SED Kudritzki, Urbaneja & Bresolin et al A2 Ia T eff = 9500 K log g = 1.45 SED fit E(B-V), R V A V extinction law HST/ACS + ground

41 E(B-V) distribution in NGC 300 Adopted by HST Key Project Freedman et al Distance 15% too large

42 B&A supergiants in M33 - reddening Adopted by HST Key Project Freedman et al Vivian U, Urbaneja, Kudritzki, Jacobs, Bresolin, 2009, ApJ 740, 1120

43 IoA 2011 M81 extinction Adopted by HST Key Project Freedman et al Distance too large Kudritzki, Urbaneja, Gazak et al., 2012, ApJ 747, 15

44 M81 FGLR D = 3.47 ± 0.16 Mpc Kudritzki, Urbaneja, Gazak et al., ApJ 747, 15

45 Conclusions and TMT/ELT perspectives WFOS quantitative spectroscopy possible down to m V ~ 24.5 mag with objects M V -8 mag m M ~ 32.5 mag ~ 30 Mpc possible chemical evolution studies SF ISM, extinction, extinction laws distances 10 objects per galaxy Δ(m-M) ~ 0.1 mag

46 red supergiants J-band spectroscopy Brightest stars at infrared light: -8 M J -11 mag B8 A4 Davies, Kudritzki, Figer, 2010 MNRAS, 407,1203 Evans, Davies, Kudritzki et al A&A, 527, 50 Keck/MOSFIRE, VLT/KMOS: 15 Mpc K M TMT/IRMS, E-ELT/EAGLE: 70 Mpc Star Super Clusters: ~10 times further out