the first stars and galaxies Raffaella Schneider INAF/Osservatorio Astronomico di Roma

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1 the first stars and galaxies Raffaella Schneider INAF/Osservatorio Astronomico di Roma

2 it was 1994 when I first met Sabino. at the XI MPI Potsdam Cosmology Workshop, Large Scale Structure in the Universe Andrei Doroshkevich Niels Bohr InsAtute Physics Department, University of Rome Valeria Ferrari Sabino

3 the FIRST team and collaborators Ma#eo de Bennassu,, Phd Luca Graziani, Pdoc Michele Ginolfi, Phd Ma8a Mancini, Phd Stefania Marassi, Pdoc Edwige Pezzulli, Phd Rosa Valiante, Pdoc Marco Bocchio, INAF/OAArcetri Simone Bianchi, INAF/OAArcetri Gen Chiaki, Tokyo University Pra,ka Dayal, Durham University Andrea Ferrara, SNS Pisa Simona Gallerani, SNS Pisa Leslie Hunt, INAF/OAArcetri Marco Limongi INAF/OAR Kazu Omukai, Tohoku University Stefania Salvadori, Kapteyn Groningen Marta Volonteri, IAP Paris h#p://

4 the formation of the first (Pop III) stars H 2 cooling favors the formation of massive stars ü collapse of 10 6 M sun mini-halos at z 20 ü H 2 cooling ü gas cloud becomes Jeans unstable M jeans 10 3 M sun M jeans 10 3 M sun accretion shock M jeans NLTE H 2 cooling thick optically thick to H 2 line H 2 collision 3body H 2 formation optically induced emission hydro-static core: 0.01 M sun H 2 dissociation Core 0.01 M sun NLTE à LTE M jeans 10 3 M sun accretion rate dm/dt M J /t ff c s3 /G T 3/2 (x 100 larger Z sun ) accreted gas mass M [ ] M sun Omukai & Palla 2003; Bromm et al 2004; O Shea et al. 2007; Tan & McKee 2004; McKee & Tan 2008; Hosokawa et al. 2011,2012; Hirano+14, Susa+14; Hirano+15 Omukai et al. 2005

5 An ab-initio calculation of the initial mass function (IMF) of Pop III stars no LW background Hirano et al LW background

6 From the first stars to the Local Universe: stellar archaeology predict the products of the first stellar explosions: metal yields, mass and composition of dust grains formed in the ejecta observe the most metal-poor stars in the present-day Universe predict the environment where second generation stars form

7 chemical yields from the first SNe metal and dust yields for Z = 0 non-rotating core-collapse SN models 1. FRANEC SN explosion models (Limongi & Chieffi 2012) 2. Mass cut tailored to minimize the difference between [X/Fe] model and [X/Fe] ave for the average metal poor star of the Galactic halo (Cayrel+ sample) lower mass progenitor: higher mass progenitor E kin = 0.5 foe M Fe = 1.34 M sun E kin = 5.22 foe M Fe = 2.08 M sun Marassi, RS, et al. (2015)

8 H 2, metal and dust-driven fragmentation: three different mass-scales T dn/dlog M * M ch n M * H 2 -line cooling: M jeans ~ 10 3 M sun Abel+(2002) Bromm+(2002) Yoshida+(2008) Z = 0 Z = 10-7 Z sun Z = 10-6 Z sun metal-line cooling: Z > 10-4 Z sun M jeans > 10 M sun OI, CII line cooling Z = 10-4 Z sun Z = 10-5 Z sun dust cooling: Z > 10-6 Z sun M jeans < 1 M sun Bromm et al. (2001) Bromm & Loeb (2003) Santoro & Shull (2004) RS et al. (2002,2003,2006), Omukai et al. (2005)

9 the most iron-poor stars in the Galactic halo 8 out of the 9 currently known stars with [Fe/H] < -4.5 are Carbon-enhanced (CEMP-no) HE [Fe/H] = [C/Fe] = Chris,lieb+02 HE [Fe/H] = [C/Fe] = Frebel+05 SMSS J [Fe/H] < -7.1 HE [Fe/H] =-4.81 [C/Fe] = Norris+07 SDSS J [Fe/H] = [C/Fe] < 0.93 Caffau+11 SMSS [Fe/H] < [C/Fe] > 4.90 Keller+14 Keller et al. 14 HE [Fe/H] = [C/Fe] = Hansen+14 SDSS J [Fe/H] = [C/Fe] = Caffau+14 SDSS J [Fe/H] < [C/Fe] > 3.40 Bonifacio+15 SDSS J [Fe/H] = -5 [C/Fe] = + 3 Allende-Prieto+15 C-enhanced & C-normal stars: 2 formation routes?

10 simulating the birth environment of C-normal and C-rich stars SDSS J [Fe/H] = SMSS J [Fe/H] < -7.1 Caffau et al 11 Keller et al 14 C NO Mg Si Ca Ti Fe Ni Sr Pop III core-collapse SNe M star = 20, 35 M sun Pop III faint SNe M star = 50, 80 M sun C NO Mg Si Ca Ti Fe Ni Sr Schneider et al Marassi et al. 2014

11 simulating the birth environment of C-normal and C-rich stars SDSS J [Fe/H] = SMSS J [Fe/H] < -7.1 Caffau et al 11 Keller et al 14 single formation pathway based on dust-driven fragmentation Silicate dust M dust ~ 0.4 M sun 0.2 < f sil < 0.6 Carbon dust M dust ~ M sun 0.01 < f carb < 0.84 Schneider et al Marassi et al. 2014

12 from the first stars to the first galaxies predict the emissivity of the first stellar populations and how the UV light propagates out of the galaxies starting cosmic reionization compare with the observed properties of the most distant galaxies predict how the light, metals and dust produced by the first stellar generations affect cosmic structure formation

13 The Milky Way reionisation simulation redshift evolution of the HII fraction and of the gas temperature Slice cuts (distances in cell units 1 cell = 15.6 h -1 kpc) Graziani+2015

14 effects of inhomogeneous radiative feedback effects of inhomogeneous radiative feedback cell units 1 cell = 15.6 h -1 kpc z = 12 z = 10 z = 6 Temperature contours: T ~ 100, 4 x 10 3, 10 4, 1.3 x 10 4, 1.5 x 10 4 K Graziani+2015

15 properties of the first galaxies SPH/GADGET2 cosmological hydrodynamical simulation of a L box = 30 Mpc/h UV luminosity function metallicities and stellar ages the most distant galaxies that we observe are already chemically mature systems, the most massive (and UV bright) are also dust-enriched Mancini, RS+2015; Graziani, RS+ in prep

16 the dust mass in normal galaxies at 5 < z < 7

17 the dust mass in z ~ 7 normal star forming galaxies Ouchi+(2013); Kanekar+(2013); Ota+(2014); Schaerer+(2014); Maiolino+(2015); Watson+(2015) dust vs stellar mass: simulation results vs observations dust evolution of the most massive galaxies grain growth stellar dust 2 Myr Mancini, RS, Graziani et al. (2015) AGB contribute to ~40% of the stellar dust

18 the dust mass in z ~ 7 normal star forming galaxies Ouchi+(2013); Kanekar+(2013); Ota+(2014); Schaerer+(2014); Maiolino+(2015); Watson+(2015) dust vs stellar mass: simulation results vs observations dust evolution of the most massive galaxies grain growth stellar dust 0.2 Myr Mancini, RS, et Graziani al. (2015, et in al. prep) (2015) efficient grain growth is required to account for the observed dust mass

19 Summary The exploration of the epoch of formation of the first stars and galaxies represents one of the main open frontiers of modern astrophysics. New insights from a combination of theoretical models and observations in the Local Universe and the highest redshifts accessible with current facilities. constraints from stellar archaeology on the nature and properties of the first supernovae and the formation mode of the first low-mass stars observed properties of the first galaxies are the result of a complex interplay of radiative and chemical feedback effects from the first stellar generations. Current z > 6 are targeting chemically mature systems important guidance for interpreting data from ongoing surveys (VLT, HST, ALMA) and for the preparation of key programs with future large telescopes (SKA, ELT, JWST)