Soltan Institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray bursts M.I. Andersen Probing the high-redshift Universe with Gamma-ray Bursts Michael I. Andersen Astrophysikalisches Institut Potsdam

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Outline 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-formation. Tracking down star- and galaxy-formation.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The Vela satellites Launched by the US military to monitor the test ban treaty. Launched by the US military to monitor the test ban treaty. Pairwise in km high orbit – 180deg apart. Pairwise in km high orbit – 180deg apart. Time delays up to 0.8sec for cosmic events. Time delays up to 0.8sec for cosmic events.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The first GRB

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The compactness problem Cavallo & Rees (1978) and Schmidt (1978) shows that self-absorption will be severe, if distance is more than ~10 kPc. Cavallo & Rees (1978) and Schmidt (1978) shows that self-absorption will be severe, if distance is more than ~10 kPc. This result was based on inferring the size of the emitting region from the variability time scale (approximately stellar). This result was based on inferring the size of the emitting region from the variability time scale (approximately stellar).

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Compton-GRO Launched de-orbited 2000 Launched de-orbited 2000

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Compton-GRO Burst And Transient Source Experiment

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen BATSE sample light curves

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Hardness-duration diagram

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Duration diagram

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The BATSE sky

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The fireball model The isotropic distribution observed by BATSE prompts Rees & Meszaros to propose the fireball model (the population must be distant). The isotropic distribution observed by BATSE prompts Rees & Meszaros to propose the fireball model (the population must be distant). The basic idea is that the radiation can only escape, if it originates in an ultra- relativistic blastwave. The basic idea is that the radiation can only escape, if it originates in an ultra- relativistic blastwave.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Theoreticians playground By 1995, about 140 theories on GRBs. By 1995, about 140 theories on GRBs. What about What about “They are due to extra terrestrial civilizations finding the infinite energy source – and making a mistake during testing.” “They are due to extra terrestrial civilizations finding the infinite energy source – and making a mistake during testing.”

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Beppo-SAX Italian-Dutch satellite, Italian-Dutch satellite, Combination of Gamma-ray detectors and X-ray telescope was a unique feature. Combination of Gamma-ray detectors and X-ray telescope was a unique feature.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen GRB Detected by Beppo-SAX in Gamma-rays Detected by Beppo-SAX in Gamma-rays Follow-up observations with the Follow-up observations with the Beppo-SAX X-ray telescope Beppo-SAX X-ray telescope First detection of a GRB at other wavelengths! First detection of a GRB at other wavelengths! → and the first precise position! → and the first precise position!

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen GRB in X-rays

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The optical afterglow

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The origin of GRB970228

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The post GRB view The distance scale is cosmological. The distance scale is cosmological. The energy release is tremendous (~10^53 erg in a minute) The energy release is tremendous (~10^53 erg in a minute) Most theories are off the table. Most theories are off the table.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The central engine

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen There is a jet! Achromatic breaks in light curves are interpreted as the presence of a jet. Achromatic breaks in light curves are interpreted as the presence of a jet. The actual energy release is thus much lower than what is inferred from assuming isotropic radiation. The actual energy release is thus much lower than what is inferred from assuming isotropic radiation. There are many more GRBs than those we observe. There are many more GRBs than those we observe.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen ROTSE observations of GRB990123

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The redshift of GRB Z = 1.60!

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The brightest object ever observed

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The energy release The isotropic energy release was equivalent to the conversion of the restmass of ~1 neutron star into energy. The isotropic energy release was equivalent to the conversion of the restmass of ~1 neutron star into energy. GRBs can destroy life to a distance of ~100 Parsec. GRBs can destroy life to a distance of ~100 Parsec.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen GRB Detected with Inter Planetary Network. Detected with Inter Planetary Network. Position known only 3½ days after the GRB, with a ~10 arcmin error box. Position known only 3½ days after the GRB, with a ~10 arcmin error box. Observed with VLT, when 4 days old. Observed with VLT, when 4 days old.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen GRB error box

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The Gamma-ray light curve

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Afterglow indentification

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The SED of the afterglow The SED of the afterglow

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen VLT spectroscopy

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Record redshift The location of Lyman forest shows that GRB was at z = 4.5. The location of Lyman forest shows that GRB was at z = 4.5. GRB remains the most distant explosion ever observed. GRB remains the most distant explosion ever observed. Look back time is ~13Gyr. Look back time is ~13Gyr.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The 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 quark stars and has been proposed. Everything from supernovae to strange quark stars and has been proposed.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen GRB /SN1998bw The smoking gun The temporal and spatial coincidence between GRB and the type Ic SN1998bw The temporal and spatial coincidence between GRB and the type Ic 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 ± 3000 km/s Expansion velocity of ± 3000 km/s Are (long) GRBs associated with SNe? Are (long) GRBs associated with SNe?

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen SN1998bw/GRB980425

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen GRB peculiar Sub-luminous in γ-rays by a factor 10^4. Sub-luminous in γ-rays by a factor 10^4. Optical afterglow fainter by 5-10 mags. Optical afterglow fainter by 5-10 mags. Not a classical burst → strong skepticism. Not a classical burst → strong skepticism.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Other smoking guns GRB – late bump on light curve GRB – late bump on light curve (Bloom et al., 1999) (Bloom et al., 1999) GRB /SN2001ke – late change of GRB /SN2001ke – late change of SED consistent with underlying supernova. SED consistent with underlying supernova. (Garnavich et al. 2003) (Garnavich et al. 2003)

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Bloom et al. Nature, 1999

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen GRB 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 distribution in top 0.2% of the BATSE fluence distribution Afterglow discovered after 1.5h, magnitude ~12! Afterglow discovered after 1.5h, magnitude ~12! (Price at al. 2003) (Price at al. 2003)

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Afterglow spectroscopy High resolution spectra with High resolution spectra with → z = → z = (Greiner et al., GCN #2000) (Greiner et al., GCN #2000) L ~ 9 x 10^51 erg ( keV) L ~ 9 x 10^51 erg ( keV) SN1998bw would be R~ 20 mag SN1998bw would be R~ 20 mag

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Late spectroscopy Observations obtained with the FORS1 and FORS2 instruments on Antu and Yepun at Paranal Spectroscopy at 6 epochs, from 4-32 days after the GRB trigger Resolution ~ 400

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Hjorth et al. Nature, 2003

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Hjorth et al. Nature, 2003

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen A Progenitor’s fingerprint The Ic SN 2003dh unambigously identified (J. Hjorth et al., Garnavich et al.) The Ic SN 2003dh unambigously identified (J. Hjorth et al., Garnavich et al.) Expansion velocity of ± 3000 km/s Expansion velocity of ± 3000 km/s (classifies as extreme hypernova) (classifies as extreme hypernova) Coeval with GRB to ± 2 days Coeval with GRB to ± 2 days

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Hjorth et al. Nature, 2003

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Implications At least some long/soft GRBs are caused At least some long/soft GRBs are caused by the death of a massive star by the death of a massive star Taken together with GRB , this is Taken together with GRB , this is compelling evidence that the death of a compelling evidence that the death of a massive star is the cause of long GRBs massive star is the cause of long GRBs

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Why type Ic SNe? Characterized by the absence of Characterized by the absence of hydrogen lines and weak or absent hydrogen lines and weak or absent He/Si lines in the spectrum He/Si lines in the spectrum → Progenitor was a Wolf-Rayet star → Progenitor was a Wolf-Rayet star which had lost its envelope (due to which had lost its envelope (due to a stellar wind or binary evolution) a stellar wind or binary evolution)

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Why a hypernova? The extreme expansion velocity may be understood as a consequence of a high core-to-envelope mass ratio The extreme expansion velocity may be understood as a consequence of a high core-to-envelope mass ratio This points towards binary evolution (efficient stripping of envelope) This points towards binary evolution (efficient stripping of envelope) → Easier to understand GRB penetration? → Easier to understand GRB penetration?

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen If a binary, then..... Easier to understand the rarity of GRBs Easier 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 be understood as the secondary going of as a GRB inside the remanant of the primary. Observed abundance anormalies could be understood as the secondary going of as a GRB inside the remanant of the primary.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Conclusions I Long GRBs appear to be caused by the core-collapse of a short-lived massive star. Long GRBs appear to be caused by the core-collapse of a short-lived massive star. On a cosmological time scale, the GRB therefore takes place nearly instantly. On a cosmological time scale, the GRB therefore takes place nearly instantly. GRB therefore trace star- and galaxy- formation from the first generation of stars. GRB therefore trace star- and galaxy- formation from the first generation of stars.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The GRB host galaxy

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The GRB host galaxy

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The distribution of GRBs

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen GRB000926: spectrum (z=2.0338)

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Conclusions II Quite independent of the physics of GRBs, we can use these spectacular events to study 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 way back to the ‘dark ages’. The reionizaion of the universe, all the way back to the ‘dark ages’.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen How to discover many GRBs? The SWIFT satellite will give100/year, but it has limited life time. The SWIFT satellite will give100/year, but it has limited life time. Alternative – discover the optical counterparts from the ground. Alternative – discover the optical counterparts from the ground. You need a very wide field permanent survey which goes sufficiently deep. You need a very wide field permanent survey which goes sufficiently deep.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Absolute magnitude at 1 day

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The afterglow Luminosity Function

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Discovery magnitude vs delay

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen Requirements for a continous all-sky survey High time resolution, 10sec or better. High time resolution, 10sec or better. Limiting magnitude of ~15 per exposure. Limiting magnitude of ~15 per exposure. Very efficient rejection of false events. Very efficient rejection of false events.

Soltan institute for Nuclear Studies Warsaw Probing the high-redshift Universe with Gamma-ray Bursts M.I.Andersen The double-PI on the sky Use an array of ~100 fast Schmidt cameras with a large CCD on each site. Use an array of ~100 fast Schmidt cameras with a large CCD on each site. Install everything inside a glass dome to convert it to a laboratory experiment. Install everything inside a glass dome to convert it to a laboratory experiment. Dublicate the installation at another site, located ~100km away (stereoscopic coincidence imaging). Dublicate the installation at another site, located ~100km away (stereoscopic coincidence imaging).