Monsters in Early Universe Myungshin Im Dept. of Physics and Astronomy Astronomy Program Seoul National University
History of the Universe Early Universe Unexplored Epoch of the Cosmic History
Theoretical Story of Early Universe I Proton (+) Cosmic Microwave Background (Nobel Prizes) + + H Photons (N) Electron (-) - - He H H Dark Age ~3x10 5 yrs ~3x10 8 yrs Proto- Galactic Gas H H First Stars (~100 M ) Re-ionization of the Universe - - + H + Proto- Galactic Gas - + H Black Holes (~10 M ) + - ~(3-10)x10 8 yrs Proto- Galactic Gas - + Supernovae ( 超新星, GRB) ~3-6 Myr H + - Heavy elements (Ingredients of life!)
Theoretical Story of Early Universe II Supermassive Black Holes (~10 6-10 9 M ) ~1x10 9 yrs Quasar (> 10 12 L ) Galaxy Cluster ~2x10 9 yrs Quasar + Galaxy
Is This Story Right? Monsters in the Universe can answer the question! Enormous Explosion: Gamma Ray Burst (GRB) Ghosts of Star: Supermassive Black Holes The Most Massive Astronomical Object: Proto-clusters of Galaxies
Gamma Ray Bursts: The Most Energetic Event in the Universe γ-ray: high energy photons (> 100 kev, nuclear bomb) Discovered first by spy satellites (1973) Duration of 0.001 1000 sec Luminosity: ~10 54 erg/sec The Sun: 2 x 10 33 erg/sec Galaxy ~ 10 43 erg/sec All galaxies in the Universe ~ 10 54 erg/sec http://science.nasa.gov
Optical Afterglow Can be as bright as 6 mag (Naked-eye burst) even at billions of light-years away GRB can be studied at very high redshift (early universe ~ 0.5 billion years old) GRB 071010B (Urata, Huang, Im, et al. 2009; Lee, Im, et al. 2010) ΔT=0.5 days ΔT=5.5 days ΔT=8.5 days
Origin of GRB Long GRB (> 2 sec): Hypernova (Extreme Supernova; e.g., Woosley & Bloom 2006) First stars (Belczynski et al. 2010; 10x) Short GRB (< 2 sec): Neutron star-neutron star merging, neutron star-black hole merging (e.g., Nakar 2007)
GRBs at High Redshift GRB 090423 (z ~ 8.2; Tanvir et al. 2009, Salvattera et al. 2009) GRB 100905A (z ~ 7.5; Im et al. 2011, prep) GRB 080930 (z ~ 6.8; Greiner et al. 2009) GRB 050904 (z ~ 6.29; Kawai et al. 2006; Totani et al. 2006) Age (Gyr) 0.6 0.7 0.8 0.9 GRB 100905A at z ~ 7.5 Lyman break (13.6 kev ~ 121.6 nm)
GRBs in Early Universe GRBs in early universe long GRB? No! All three GRBs at z > 6.5 Short GRBs! Great Mystery. BZ process? (Blandford- Znajek 1977) Short
Supermassive Black Holes (SMBH) What are they? - Black Holes with masses ~ 10 6 10 10 M Where are they? - Centers of massive spheroids/bulges or quasars Elliptical galaxy Bulges of Spirals Quasars/AGNs
Quasars Lee, Im, et al. 2008 Looks like a star (QUAsi-StellAR radio sources) Shines via accretion of matters around SMBHs Highest redshift QSO at z=6.43 (Willott et al. 2009)
Mass of BH When Did They Appear? AKARI points (Our result) Quasar Cliff? Present day Early Universe 10 10 M SMBHs are stilll forming at z ~ 6 (0.95 Gyr) What Happened before? Quasar Cliff?
Growth of SMBHs E= ε M c 2, L = de/dt ~ ε dm/dt c 2 dm/dt = L(Edd)/c 2 / ε = M/τ, where τ ~ 4.5 x 10 7 (ε/0.1) yrs M(t) = M(seed) exp(t/τ), exponential growth Between z=15 to z=6, only 0.5 Gyr difficult to make SMBHs Volonteri & Rees (2006) ε=0.1 Super-critical ε=0.2 ε=0.4 Sijacki, Springel, & Haehnelt (2009) Age
Galaxy Clusters The most massive, gravitationally bound object in the Universe (~10 15 M ) 100-1000 member galaxies
Recent proto-cluster studies Abundance: Sensitive to cosmological parameters, initial conditions Search for proto-clusters (Miley et al. 2004; Overzier et al. 2008, Matsuda et al. 2011; Kajisawa et al. 2006; Capak et al. 2011, ; 1 < z < 5.3)
Proto-clusters in Early Universe Discovered a proto-cluster at z=3.7 (t ~ 1.7 billion years) Mass: 10 14 M Also proto-clusters at z=3.1 (Matsuda, Yamada et al.), z=4.1 (Miley et al. 2004), z=5.3 (Capak et al. 2011) Kang & Im (2009)
Implication Ph.D Thesis Kang, E. (2010) Too many massive proto-clusters at high redshift! another mystery
What Have We Learned? Death of First Stars - GRB Theory Observation? Long GRB Short GRB Why? Supermassive BH Growth Theory Observation? ~1 Gyr Rapid Growth How? Proto-clusters in Early Universe Theory Observation? Rare 100x more Strange
Summary Extreme Objects in Early Universe GRB, SMBH, and Proto-clusters Current results present challenges to theoretical/observational studies Exciting era to study the first objects in the universe