The Dark Ages of the Universe Naoki Yoshida Physics / Kavli IPMU - - PowerPoint PPT Presentation

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The Dark Ages of the Universe Naoki Yoshida Physics / Kavli IPMU - - PowerPoint PPT Presentation

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NTU/ASIAA Joint Colloquium May 13, 2014 The Dark Ages of the Universe Naoki Yoshida Physics / Kavli IPMU University of Tokyo C ONTENTS From the big bang to the first stars A missing piece in cosmic history First light The

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The Dark Ages

  • f the Universe

NTU/ASIAA Joint Colloquium May 13, 2014 Naoki Yoshida Physics / Kavli IPMU University of Tokyo

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CONTENTS

✦ From the big bang to the first stars

  • ✦ First light
  • ✦ Early blackholes and supernovae

References: Hosokawa, Omukai, NY, Yorke, 2011, Science Bromm, NY, 2011, ARAA Hosokawa, Yorke, Omukai, Inayoshi, NY, 2013, ApJ Tanaka, Moriya, NY, 2013, MN Hirano et al. 2014, ApJ

A missing piece in cosmic history

  • The mass of the first stars
  • Setting the scene for galaxy formation
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γ-ray burst

0 10 20 30 40 [sec]

Photon count by Swift sat.

X-ray image

Afterglow

  • Every few days
  • From all directions on

the sky (=extragalactic)

  • The record redshift of

z=9.4! ~ 13.5 billion light yrs

Relativistic jet from the central black hole Death of a massive star

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A YOUNG BUT BIG! BLACKHOLE

2 billion times heavier than the sun 13 billion light years away (130

  • Light in various wavelengths
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Stellar relics in the Milky Way

A “forbidden” star Low-mass (<1Msun), extremely metal-poor (not only iron-poor) Metallicity below 4.5 x 10-5 that of the sun.

Caffau et al. 2012, Nature

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No spectral features

Ordinary stars like the sun contains a few percent (in mass) of heavy elements → many lines in the spectrum

  • There are many stars in Galaxy

that contain less amount of heavey elements

  • A few of them contain almost

no elements other than hydrogen and helium. Sun

wavelength

Fe

Sun

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Seemingly different phenomena

  • Prompt emission of high-energy photons
  • Emergence of a super-massive blackhole
  • A nearby star with very low metal content

They may have the same origin, which is also related, ultimately, to the beginning of our own existence.

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THE COSMIC HISTORY

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The Dark Ages

  • dsf

Has not been observed by any wavelength

~2-300 million years

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In the beginning, there was a sea of light elements and dark matter…

  • and tiny ripples left over

from the Big Bang

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Compare with present-day star formation

Turbulence Cosmic rays Supernovae Stellar winds Radiation Magnetic field

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Early universe

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STANDARD COSMOLOGICAL MODEL

  • THEORY OF STAR FORMATION

molecular cloud protostar star

4% 22% 74%

inflation dark matter early structure

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FIRST STAR NURSERIES

Web-like structure in the early universe. Yellow spots are clumps of dark matter. First star nurseries are 1000 times heavier than the sun. Strongly clustered.

  • Matter distribution

Tage = 300 million years

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PRIMORDIAL GAS CLOUD

H

He

Gravity Radiative cooling

H2 (0.01%)

Simple picture

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  • Resolving planetary

scale structures in a cosmological volume!

  • A complete picture
  • f how a protostar

is formed from tiny density fluctuations.

  • From primeval ripples

to a protostar

Minihalo Molecular cloud New-born protostar NY, Omukai, Hernquist 2008 25 solar-radii 5pc 300pc

  • 106 Msun
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Physics is hard

adiabatic contraction H2 formation line cooling

(NLTE)

loitering

(~LTE)

3-body reaction Heat release

  • paque to

molecular line collision induced emission

T [K]

104 103 102

number density

  • paque to

continuum and dissociation A proto-star (hydrostatic core) The Physics

Thermal evolution (EoS)

NY, Hosokawa, Omukai, PTEP 2012

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Hyper-accreting protostar

hydrostatic core

  • uter envelope

The central protostar accretes the surrounding gas at a very large rate:

  • A “classic” picture

dM/dt ∝ T1.5/G = 0.01-0.1 Msun/yr

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The mass and the fate of a star

mass lifetime fate 1 solar ~ 10 billion years white dwarf

  • 10 ~ 10 million years supernova
  • 200 ~ 2 million years energetic

> 1 million times brighter than the sun

supernova

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Theorists said....

2000 2002 2004 2006 2008 2010 2012

10 100 1000

  • Msun
  • hkubo

ny johnson mckee tan hosokawa clark

  • mukai

bromm abel jeans mass accretion time protostar evolution 1D HD PopIII.2 Disk evap. core evolution Disk fragment protostar feedback

mass “evolution”

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Protostars grow through gas accretion, mergers, plus, protostellar feedback

  • ver ~ 100,000 years

gas cloud protostar star

The Key Question How and when does a first star stop growing ?

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Bi-polar HII regions vs accretion flow.

  • Self-regulation

mechanism.

temp. density

  • utflow

hot cold

Pressure-driven outflow around a protostar

McKee-Tan08; Hosokawa+11; Stacey+12

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Final mass of a first star

Accretion rate onto the protostar

Photo-dissociation Cloud evaporation

Final mass

Hosokawa, Omukai, NY, Yorke, 2011, Science

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A long standing puzzle … resolved.

Iwamoto et al. 2005 Abundance pattern from a 25 Msun Hypernova model

  • Observed elemental

abundances

SN models of 20-40 Msun progenitor

Metal-poor stars were formed from a gas cloud enriched by the first supernova explosions

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100 First Stars

Hirano, NY+ 2014, ApJ

Cosmological hydro

simulation + radiation-hydro calculation of protostellar evolution

  • 100 star forming

clouds located in the cosmological volume.

  • Characteristic mass
  • f the first stars
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Toward Primordial IMF

Imagine this enormous effort...

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The result : final masses

Collapse to BH

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3 evolutionary paths

stellar mass stellar radius

m a i n s e q u e n c e

dM/dt =

By Hirano & Hosokawa

KH contract.

accreting protostar

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Hunting for the first supernova explosions

Tanaka, Moriya, NY, Nomoto 2012, MNRAS, 422, 2675 Moriya et al. 2013, MNRAS, 428, 1020 Tanaka, Moriya, NY, arxiv 1306.3743

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Distant supernova

Type IIn at z=2.4

Cooke et al. 2009, 2012, Nature

brightness variation 11 billion light years away

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Powered by shock- interaction with dense gas cloud Bright in ultra-violet Death of a very massive star (> 50 Msun?) They will be visible to very high-z.

Teff = 12000 K

Super-luminous supernovae

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Super-Luminous SN

Powered by shock- interaction with dense CSM. Bright in rest-UV Death of a very massive star (> 50 Msun?) They will be visible to very high-z.

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Monte-Carlo Simulation

  • Distinguished from low-z SN

example

Model Spectra + SN occurance rate SED evolution

Locally calibrated SN

  • ccurance rate

Tanaka, Moriya, NY, Nomoto 2012

Light curve

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Subaru-HSC 2014-

Number

color selection

Tanaka, Moriya, NY, Nomoto, 2012

3.5 deg2

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Probing stellar mass

Salpeter 100 deg2 1-4 μm SLSN progenitors are the high-mass end of the population

How many massive stars are formed.

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Future surveys

Tanaka, Moriya, NY 2013

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Personal goal

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First blackholes

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Blackhole mass

Marziani+11

(super-) Eddington mild evolution ? BigBang 1Gyr 2Gyr ← time 109 107 1011 1010 108

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Blackhole seeds: Rees diagram

Volonteri 2012, Science

PopIII remnant via a super-massive star

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Blackhole growth t=0.2 0.5 0.8 Gyr 109 105 102

MBH

popiii remnant direct collapse smbh “

  • b

s e r v e d ”

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Direct collapse model

Strong radiation

Latif+13, A&A

See also Regan & Haehnelt 2011; Choi+2013

dM/dt ~ T1.5/G

~ 1Msun/year

Super Massive Star ~ 105 Msun

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Supergiant star

stellar mass stellar radius

m a i n s e q u e n c e

dM/dt > 0.06 Msun/yr

Hosokawa, Yorke, Inayoshi, Omukai, NY 2013, ApJ

KH contract.

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100,000 Msun star

Low effective Temp → no UV feedback 1 10 100 1000 104 105 Radius mass

L ∝ M , R

∝

M1/2

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James Webb Space Telescope

By T. Hosokawa

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Gravitational stability

General relativistic instability

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Blackhole growth z=30 20 15 10 7 109 105 102

MBH

popiii dc smbh

Large gap

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Summary

  • Formation of massive primordial stars as
  • rigin of objects in the early universe
  • Supernova explosions might be visible to

the most distant places

  • Rapid growth of a primordial star makes

a supermassive star and possibly a BH