the population iii connection jonathan devor. outline grbs as cosmological probes: why is this...
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![Page 1: The Population III Connection Jonathan Devor. Outline GRBs as Cosmological Probes: Why is this interesting? Population III – A brief historical overview](https://reader035.vdocuments.us/reader035/viewer/2022062714/56649d375503460f94a10652/html5/thumbnails/1.jpg)
The Population III ConnectionJonathan Devor
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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?
• Cosmological model
• Big bang nucleosynthesis
• First stars (population III)
• Galactic formation
• Reionization epoch
• Early IGM metallicity enhancement
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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)
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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
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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
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CDM at z=17
Taken from (Yoshida 2003)Taken from Swift website
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Primordial gas
Taken from (Bromm 2002)
Adiabatic H2 cooling
Stable point Gravitycompression
Lingers at: T~200K3410~ cmn
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Jean’s instability criterion
2/1
34
2/3
3
2
3
10200700
)22.1()(
)(:
cm
n
K
TMM
mRnRMM
Gn
kT
G
kTR
R
RGkTUnstable
solJ
pJJJ
J
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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)
HHH 23)10( 38 cmn
cGM
LEdd
4
eHHHHeH 2
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Clump evolution
Taken from (Omukai 1998)
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Growth of protostar
The accretion is effectively shut off at some critical value because of the dramatic increase in radius
Taken from(Omukai 2003)
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Pop. III supernovae
< 140 M Type II SNe
(core collapse)
Low yield
140-260 M Pair-instability supernova (PISN)
No remnant High yield ½M metals
> 260 M Massive black hole (MBH)
High accretion No yield (quasar?)
ergE 5310
•Life time: yearsL
cM
Edd
62
* 103007.0
ergE 5110
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Pop. III star – remnant
ergEyearst 536 10;10
400 pc
fragmentation
metals
Taken from(Bromm 2003)
SPH simulation
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Reionization
HI 13.6 eV
HeI 24.6 eV
HeII 54.4 eV
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 )
1010~510~
Taken from (Wyithe 2003)
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What can we see?
All GRBsSwiftBATSE
Taken from (Bromm 2002)
With Swift, 10-25% of GRB afterglows will come from z > 5
That is, about a dozen a year!
Taken from (Lamb 2002)
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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)
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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
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The Swift SongWe 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!)
Chorus: 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?