Soltan Institute for Nuclear Studies Warsaw 14.01.2005 Probing the high-redshift Universe with Gamma-ray bursts M.I. Andersen Probing the high-redshift.

Soltan Institute for Nuclear Soltan Institute for Nuclear StudiesStudiesWarsaw 14.01.2005Warsaw 14.01.2005

Probing the high-redshift Universe with Gamma-ray bursts M.I. Andersen

Probing the high-redshift Probing the high-redshift Universe with Gamma-ray Universe with Gamma-ray

Bursts Bursts

Michael I. AndersenMichael I. AndersenAstrophysikalisches Institut Astrophysikalisches Institut

PotsdamPotsdam

Soltan institute for Nuclear Soltan institute for Nuclear StudiesStudiesWarsaw 14.01.2005Warsaw 14.01.2005

Probing the high-redshift Universe with Gamma-ray Probing the high-redshift Universe with Gamma-ray BurstsBursts

M.I.AndersenM.I.Andersen

Outline of talkOutline of talk

A brief history of GRB’s.A brief history of GRB’s. An emerging scenario, the progenitor.An emerging scenario, the progenitor. Tracking down star- and galaxy-Tracking down star- and galaxy-

formation.formation.




The Vela satellitesThe Vela satellites

Launched by the US military to Launched by the US military to monitor the test ban treaty.monitor the test ban treaty.

Pairwise in 110000km high orbit – Pairwise in 110000km high orbit – 180deg apart.180deg apart.

Time delays up to 0.8sec for cosmic Time delays up to 0.8sec for cosmic events.events.







The first GRBThe first GRB







The compactness The compactness problemproblem

Cavallo & Rees (1978) and Schmidt Cavallo & Rees (1978) and Schmidt (1978) shows that self-absorption will be (1978) shows that self-absorption will be severe, if distance is more than ~10 kPc.severe, if distance is more than ~10 kPc.

This result was based on inferring the This result was based on inferring the size of the emitting region from the size of the emitting region from the variability time scale (approximately variability time scale (approximately stellar).stellar).




Compton-GROCompton-GRO Launched 1991. de-orbited 2000Launched 1991. de-orbited 2000




Compton-GROCompton-GRO

Burst And Transient Source Burst And Transient Source ExperimentExperiment




BATSE sample light curves BATSE sample light curves




Hardness-duration Hardness-duration diagramdiagram




Duration diagramDuration diagram




The BATSE sky The BATSE sky




The fireball modelThe fireball model

The isotropic distribution observed The isotropic distribution observed by BATSE prompts Rees & Meszaros by BATSE prompts Rees & Meszaros to propose the fireball model (the to propose the fireball model (the population must be distant).population must be distant).

The basic idea is that the radiation The basic idea is that the radiation can only escape, if it originates in an can only escape, if it originates in an ultra-relativistic blastwave. ultra-relativistic blastwave.




Theoreticians Theoreticians playgroundplayground

By 1995, about 140 theories on By 1995, about 140 theories on GRBs.GRBs.

What about.......What about.......

““They are due to extra terrestrial civilizations They are due to extra terrestrial civilizations finding the infinite energy source – and finding the infinite energy source – and making a mistake during testing.making a mistake during testing.””




Beppo-SAX Beppo-SAX

Italian-Dutch Italian-Dutch satellite, 1996-satellite, 1996-2002.2002.

Combination of Combination of Gamma-ray Gamma-ray detectors and X-detectors and X-ray telescope was ray telescope was a unique feature.a unique feature.




GRB 970228GRB 970228

Detected by Beppo-SAX in Gamma-raysDetected by Beppo-SAX in Gamma-rays

Follow-up observations with the Follow-up observations with the

Beppo-SAX X-ray telescopeBeppo-SAX X-ray telescope

First detection of a GRB at other First detection of a GRB at other wavelengths!wavelengths!

→ → and the firstand the first precise position! precise position!




GRB970228 in X-raysGRB970228 in X-rays




The optical afterglowThe optical afterglow




The origin of GRB970228The origin of GRB970228




The post GRB970228 The post GRB970228 viewview

The distance scale is cosmological.The distance scale is cosmological. The energy release is tremendous The energy release is tremendous

(~10^53 erg in a minute) (~10^53 erg in a minute) Most theories are off the table. Most theories are off the table.




The central engineThe central engine




There is a jet!There is a jet!

Achromatic breaks in light curves are Achromatic breaks in light curves are interpreted as the presence of a jet.interpreted as the presence of a jet.

The actual energy release is thus The actual energy release is thus much lower than what is inferred much lower than what is inferred from assuming isotropic radiation.from assuming isotropic radiation.

There are many more GRBs than There are many more GRBs than those we observe.those we observe.




ROTSE observations of ROTSE observations of GRB990123GRB990123




The redshift of The redshift of GRB990123GRB990123

Z = Z = 1.60!1.60!




The brightest object The brightest object ever observedever observed




The energy releaseThe energy release

The isotropic energy release was The isotropic energy release was equivalent to the conversion of the equivalent to the conversion of the restmass of ~1 neutron star into restmass of ~1 neutron star into energy. energy.

GRBs can destroy life to a distance of GRBs can destroy life to a distance of ~100 Parsec. ~100 Parsec.




GRB000131GRB000131

Detected with Inter Planetary Detected with Inter Planetary Network.Network.

Position known only 3½ days after the Position known only 3½ days after the GRB, with a ~10 arcmin error box.GRB, with a ~10 arcmin error box.

Observed with VLT, when 4 days old.Observed with VLT, when 4 days old.




GRB000131 error boxGRB000131 error box




The Gamma-ray light The Gamma-ray light curvecurve




Afterglow indentificationAfterglow indentification




The SED of the afterglowThe SED of the afterglow




VLT spectroscopyVLT spectroscopy




Record redshiftRecord redshift

The location of Lyman forest shows The location of Lyman forest shows that GRB000131 was at that GRB000131 was at z = 4.5.z = 4.5.

GRB000131 remains the most GRB000131 remains the most distant explosion ever observed.distant explosion ever observed.

Look back time is ~13Gyr.Look back time is ~13Gyr.




The progenitor at largeThe progenitor at large

From early GRB observations it was clear From early GRB observations it was clear

that the progenitor was of ~ stellar size.that the progenitor was of ~ stellar size. (as inferred from the variability time scale of ~ seconds)(as inferred from the variability time scale of ~ seconds)

The quest for the progenitor is a 30 year old problem!The quest for the progenitor is a 30 year old problem!

Everything from supernovae to strange Everything from supernovae to strange quark stars and has been proposed.quark stars and has been proposed.




GRB 980425/SN1998bwGRB 980425/SN1998bw The smoking gun The smoking gun

The temporal and spatial coincidence The temporal and spatial coincidence between GRB980425 and the type Ic between GRB980425 and the type Ic SN1998bw SN1998bw

(Galama et al. 1998)(Galama et al. 1998)

Located in a low redshift (z=0.0085) galaxy.Located in a low redshift (z=0.0085) galaxy. Expansion velocity of 23000 ± 3000 km/sExpansion velocity of 23000 ± 3000 km/s Are (long) GRBs associated with SNe?Are (long) GRBs associated with SNe?




SN1998bw/GRB980425SN1998bw/GRB980425




GRB 980425 peculiarGRB 980425 peculiar

Sub-luminous in Sub-luminous in γγ-rays by a factor 10^4.-rays by a factor 10^4.

Optical afterglow fainter by 5-10 mags.Optical afterglow fainter by 5-10 mags.

Not a classical burst Not a classical burst → strong skepticism.→ strong skepticism.




Other smoking gunsOther smoking guns

GRB 980329 – late bump on light curveGRB 980329 – late bump on light curve (Bloom et al., 1999)(Bloom et al., 1999)

GRB 011121/SN2001ke – late change ofGRB 011121/SN2001ke – late change of

SED consistent with underlying SED consistent with underlying supernova.supernova.

(Garnavich et al. 2003)(Garnavich et al. 2003)




Bloom et al.Nature, 1999




GRB 030329GRB 030329

Localized by HETE Localized by HETE (Vanderspek et al. GCN #1997)(Vanderspek et al. GCN #1997)

Fluence ~ 1.2 x 10^-4 erg/cm^2 Fluence ~ 1.2 x 10^-4 erg/cm^2 →→

in top 0.2% of the BATSE fluence distributionin top 0.2% of the BATSE fluence distribution

Afterglow discovered after 1.5h, magnitude Afterglow discovered after 1.5h, magnitude ~12! ~12!

(Price at al. 2003)(Price at al. 2003)




Afterglow spectroscopyAfterglow spectroscopy

High resolution spectra with UVES@VLTHigh resolution spectra with UVES@VLT → → z =z = 0.1685 0.1685 (Greiner et al., GCN #2000)(Greiner et al., GCN #2000)

L ~ 9 x 10^51 erg (30-400 keV)L ~ 9 x 10^51 erg (30-400 keV)

SN1998bw would be R~ 20 magSN1998bw would be R~ 20 mag




Late spectroscopyLate spectroscopy

Observations obtained Observations obtained withwith

the FORS1 and FORS2the FORS1 and FORS2

instruments on Antu andinstruments on Antu and

Yepun at ParanalYepun at Paranal

Spectroscopy at 6 epochs,Spectroscopy at 6 epochs,

from 4-32 days after thefrom 4-32 days after the

GRB triggerGRB trigger

Resolution ~ 400Resolution ~ 400




Hjorth et al. Nature, 2003




Hjorth et al. Nature, 2003




A Progenitor’s A Progenitor’s fingerprintfingerprint

The Ic SN 2003dh unambigously The Ic SN 2003dh unambigously identified identified (J. Hjorth et al., Garnavich et al.)(J. Hjorth et al., Garnavich et al.)

Expansion velocity of 36000 ± 3000 Expansion velocity of 36000 ± 3000 km/skm/s

(classifies as extreme hypernova)(classifies as extreme hypernova)

Coeval with GRB 030329 to ± 2 daysCoeval with GRB 030329 to ± 2 days




Hjorth et al.Nature, 2003




ImplicationsImplications

At least some long/soft GRBs are causedAt least some long/soft GRBs are caused

by the death of a massive starby the death of a massive star

Taken together with GRB 980425, this isTaken together with GRB 980425, this is

compelling evidence that the death of acompelling evidence that the death of a

massive star is the cause of long GRBsmassive star is the cause of long GRBs




Why type Ic SNe?Why type Ic SNe?

Characterized by the absence of Characterized by the absence of

hydrogen lines and weak or absenthydrogen lines and weak or absent

He/Si lines in the spectrumHe/Si lines in the spectrum

→ → Progenitor was a Wolf-Rayet star Progenitor was a Wolf-Rayet star

which had lost its envelope (due which had lost its envelope (due toto

a stellar wind or binary evolution)a stellar wind or binary evolution)




Why a hypernova?Why a hypernova?

The extreme expansion velocity may be The extreme expansion velocity may be understood as a consequence of a high understood as a consequence of a high core-to-envelope mass ratiocore-to-envelope mass ratio

This points towards binary evolution This points towards binary evolution (efficient stripping of envelope)(efficient stripping of envelope)

→ → Easier to understand GRB Easier to understand GRB penetration?penetration?




If a binary, then.....If a binary, then.....

Easier to understand the rarity of GRBsEasier to understand the rarity of GRBs (10^6 times less frequent than type II SNe)(10^6 times less frequent than type II SNe)

Observed abundance anormalies could Observed abundance anormalies could be understood as the secondary going be understood as the secondary going of as a GRB inside the remanant of the of as a GRB inside the remanant of the primary.primary.




Conclusions IConclusions I

Long GRBs appear to be caused by Long GRBs appear to be caused by the core-collapse of a short-lived the core-collapse of a short-lived massive star.massive star.

On a cosmological time scale, the On a cosmological time scale, the GRB therefore takes place nearly GRB therefore takes place nearly instantly. instantly.

GRB therefore trace star- and galaxy-GRB therefore trace star- and galaxy-formation from the first generation of formation from the first generation of stars.stars.




The GRB 990705 host The GRB 990705 host galaxygalaxy




The GRB000926 host The GRB000926 host galaxygalaxy




The distribution of GRBsThe distribution of GRBs




GRB000926: spectrum GRB000926: spectrum (z=2.0338)(z=2.0338)




Conclusions IIConclusions II

Quite independent of the physics of GRBs,Quite independent of the physics of GRBs,

we can use these spectacular events to we can use these spectacular events to studystudy

The first generation of stars.The first generation of stars. Early galaxy formation. Early galaxy formation. The chemical enrichment of the universe.The chemical enrichment of the universe. The reionizaion of the universe, all the The reionizaion of the universe, all the

way back to the ‘dark ages’.way back to the ‘dark ages’.




How to discover many How to discover many GRBs?GRBs?

The SWIFT satellite will give100/year, The SWIFT satellite will give100/year, but it has limited life time.but it has limited life time.

Alternative – discover the optical Alternative – discover the optical counterparts from the ground.counterparts from the ground.

You need a very wide field permanent You need a very wide field permanent survey which goes sufficiently deep.survey which goes sufficiently deep.




Absolute magnitude at 1 Absolute magnitude at 1 dayday




The afterglow The afterglow Luminosity FunctionLuminosity Function




Discovery magnitude vs Discovery magnitude vs delaydelay




Requirements for Requirements for a continous all-sky surveya continous all-sky survey

High time resolution, 10sec or better.High time resolution, 10sec or better. Limiting magnitude of ~15 per Limiting magnitude of ~15 per

exposure.exposure. Very efficient rejection of false Very efficient rejection of false

events.events.




The double-PI on the The double-PI on the skysky

Use an array of ~100 fast Schmidt Use an array of ~100 fast Schmidt cameras with a large CCD on each cameras with a large CCD on each site.site.

Install everything inside a glass dome Install everything inside a glass dome to convert it to a laboratory to convert it to a laboratory experiment.experiment.

Dublicate the installation at another Dublicate the installation at another site, located ~100km away site, located ~100km away (stereoscopic coincidence imaging).(stereoscopic coincidence imaging).

Soltan Institute for Nuclear Studies Warsaw 14.01.2005 Probing the high-redshift Universe with Gamma-ray bursts M.I. Andersen Probing the high-redshift.

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