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The Population III Connection Jonathan Devor. Outline. GRBs as Cosmological Probes: Why is this interesting? Population III – A brief historical overview The primordial IMF Stars: Then and now Supernovae What can we hope to see? The road ahead.

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  • GRBs as Cosmological Probes: Why is this interesting?

  • Population III – A brief historical overview

  • The primordial IMF

  • Stars: Then and now

  • Supernovae

  • What can we hope to see?

  • The road ahead

Grbs as cosmological probes why is this interesting
GRBs as Cosmological Probes: Why is this interesting?

  • Cosmological model

  • Big bang nucleosynthesis

  • First stars (population III)

  • Galactic formation

  • Reionization epoch

  • Early IGM metallicity enhancement

Population iii a brief historical overview
Population III – A brief historical overview

  • (Baade 1944) – star populations:

    Pop. I: Sun-like (1 - 2% metals by mass)

    Pop. II: Globular cluster-like (0.01 – 0.1%)

    Pop. III: No metals (actually < 0.001%)

  • (Schwarzschild et al. 1953):

    First model for pop. III stars

    (far less complex than type I stars in a modern environment)

Ongoing work
Ongoing work

  • 1980’s: Cosmological consequences-

  • Effects on CMB (SZ effect)

  • “Primordial” abundances of Helium

  • “Pregalactic metal enrichment”

  • Reionization epoch

  • Effects on early galactic formation

  • 1990’s: clump/star formation

  • 2000’s: WMAP, Swift, JWST

Space missions
Space Missions…

  • BATSE (1991-2000) = Burst and Transient Source Experiment [5-1,500 keV ]

  • WMAP (2003-) =

    Wilkinson Microwave Anisotropy Probe [22-90 GHz]

  • Swift (2004-)

  • JWST (2011-) = James Webb Space Telescope

  • EXIST =Energetic X-ray Imaging Survey Telescope

    5-100 KeV: x10-20 better than Swift

    100-600 KeV: x300 better than HEAO-A3 survey

Cdm at z 17
CDM at z=17

Taken from (Yoshida 2003)

Taken from Swift website

Primordial gas
Primordial gas


H2 cooling

Stable point



Taken from (Bromm 2002)

Lingers at: T~200K

Protostellar collapse
Protostellar collapse

  • No dust, no metal – need H2 as coolent

    - Free electron catalyzer (feedback from UV)

    - 3-body channel  Clump breakup

  • Radiation pressure dominated

    (very low opacity- electron scatter)

  • Halo breakup Nstar ~ 1-5

    (if N=1, problem getting rid of the angular momentum)

Clump evolution
Clump evolution

Taken from (Omukai 1998)

Growth of protostar
Growth of protostar

Taken from

(Omukai 2003)

The accretion is effectively shut off at some critical value because of the dramatic increase in radius

Pop iii star remnant
Pop. III star – remnant

SPH simulation

400 pc



Taken from

(Bromm 2003)


Taken from (Wyithe 2003)

Though comparable in brightness, GRB afterglows release less energy than quasars into the IGM (ionizes M of hydrogen). So they have a negligible effect on their environment

(with the exception of dwarf galaxies )

What can we see
What can we see?

With Swift, 10-25% of GRB afterglows will come from z > 5

That is, about a dozen a year!

All GRBs



Taken from (Bromm 2002)

Taken from (Lamb 2002)

The road ahead open questions
The road ahead – open questions

  • Do pop. III stars exist?

    Need observations!!! (Swift?)

  • Do their supernovae make GRBs? (quenching?)

  • Primordial environment

  • Primordial IMF / star formation history

    (GRB redshift distribution)

  • Early cosmological formation (filaments, galaxies)

  • “Extreme physics” (SNe, MBH)

Some references
Some references

  • Historical:

  • Schwarzschild M.,”Inhomogeneous Stellar Models. III. Models with Partially Degenerate Isothermal Cores.”, 1953, Astrophysical Journal, vol. 118, p.326

  • Survey papers:

    - Bromm V. and Larson R., “The First Stars”, 2003, astro-ph/0311019

    - Bromm V., “The First Sources of Light‘, asyro-ph/0211292

    - Lamb D., “Gamma-Ray Bursts as a Probe of Cosmology”, 2002, astro-ph/0210434

    - Loeb A. and Barkana R.,”The reionization of the Universe by the First stars and Quasars”, Annu. Rev. Astron. Astrophys., 2001, 39:19-66

    - Loeb A., “Observing the First Stars, One Star a Time”, 2003, astro-ph/0307231

The swift song
The Swift Song

We know that gamma ray explosions happen randomly all over the sky (It's like a lottery: a ticket for each square degree)

You see a FLASH! and then there's not another till about a day has gone by (But that depends upon detector sensitivity)

In just a moment they spew energy worth (That's pretty fast) A value we can't even fathom on Earth (It's really vast!)

But just what's giving rise to gamma ray sparked skies? Is it the death cry of a massive star or black hole birth? (Or both, or both? or both!)


Swiftly swirling, gravity twirling

Neutron stars about to collide

Off in a galaxy so far away

Catastrophic interplay

A roller coaster gamma ray ride

Superbright explosion then

Never to repeat again

How are we supposed to know?

How about a telescope rotation

Swiftly onto the location

Of its panchromatic afterglow?