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Recent Progress in Gamma-ray Bursts:

S. R. Kulkarni

California Institute of Technology

Image Credit: NASA E/PO, Sonoma State University, Aurore Simonnet

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Long & Short

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The Gang and collaboratorsT. Piran, Hebrew U.P. A. Price, U. HawaiiJ. Rich, ANUM. Rauch, CarnegieK. Roth, Gemini ObsM. Roth, CarnegieD. J. Sand, CaltechB. P. Schmidt, ANUS. Shectman, CarnegieA. M. Soderberg, CaltechM. Takada, Tohuku U.T. Totani, Kyoto U.W. T. Vestrand, LANLD. Watson, U. CopenhagenR. White, LANLP. Wozniak, LANLJ. Wren, LANL

G. Kosugi, NAOJ W. Krzeminski, CarnegieS. R. Kulkarni, CaltechP. Kumar, U. TexasD. C. Leonard, CaltechB. L. Lee, U. TorontoA. MacFadyen, IASP. J. McCarthy, CarnegieD. -S. Moon, CaltechD. C. Murphy, CarnegieE. Nakar, CaltechH. S. Park, LLNLB. Penprase, Pomona C.S. E. Persson, CarnegieB. A. Peterson, ANUM. M. Phillips, Carnegie

K. Aoki, NAOJE. Berger, CarnegieP. B. Cameron, CaltechR. A. Chevalier, U. VirginiaS. B. Cenko, CaltechL. L. Cowie, U. HawaiiA. Dey, NOAOS. Evans, LANLD. B. Fox, Penn S./CaltechD. A. Frail, NRAOH. Furusawa, TITA. Gal-Yam, CaltechF. A. Harrison, CaltechK. C. Hurley, UC BerkeleyM. M. Kasliwal, CaltechN. Kawai, TIT

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CollaboratorsT. Piran, Hebrew U.P. A. Price, U. HawaiiJ. Rich, ANUM. Rauch, CarnegieK. Roth, Gemini ObsM. Roth, CarnegieD. J. Sand, CaltechB. P. Schmidt, ANUS. Shectman, CarnegieA. M. Soderberg, CaltechM. Takada, Tohuku U.T. Totani, Kyoto U.W. T. Vestrand, LANLD. Watson, U. CopenhagenR. White, LANLP. Wozniak, LANLJ. Wren, LANL

G. Kosugi, NAOJ W. Krzeminski, CarnegieS. R. Kulkarni, CaltechP. Kumar, U. TexasD. C. Leonard, CaltechB. L. Lee, U. TorontoA. MacFadyen, IASP. J. McCarthy, CarnegieD. -S. Moon, CaltechD. C. Murphy, CarnegieE. Nakar, CaltechH. S. Park, LLNLB. Penprase, Pomona C.S. E. Persson, CarnegieB. A. Peterson, ANUM. M. Phillips, Carnegie

K. Aoki, NAOJE. Berger, CarnegieP. B. Cameron, CaltechR. A. Chevalier, U. VirginiaS. B. Cenko, CaltechL. L. Cowie, U. HawaiiA. Dey, NOAOS. Evans, LANLD. B. Fox, Penn S./CaltechD. A. Frail, NRAOH. Furusawa, TITA. Gal-Yam, CaltechF. A. Harrison, CaltechK. C. Hurley, UC BerkeleyM. M. Kasliwal, CaltechN. Kawai, TIT

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Long Duration Bursts:

Collapsar Model: Woosley, Heger, MacFadyen

Kulkarni et al.Bloom et al.Frail et al.Berger et al.Soderberg etal

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SN 1998bw/GRB 980425

Galama et al. 1998, Kulkarni et al. 1998 E~1048 erg (isotropic)

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Collapsar: The Movie

A Hollywood-Bollywood Production

From Bogus Enterprise,A Division of General

Propaganda

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QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

With physics and lots of hardwork (MacFadyen)

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A New Family of Cosmic Explosions:

Soderberg

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Keck Laser Guide Star AO

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Progenitors of Ibc SNe: A Hot Result

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Palomar 60-inch: A second life

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Exploitation of GRBs has already begun

Reichart et al. 2005 Berger et al.

GRB 050904: z=6.2Observations at 3 hours (P60, optical; SOAR, NIR)

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Two classes of GRBs

Short - Hard

Long - Soft

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Summarizing Four Papers

1. Fox et al. “The afterglow of GRB 050709 and the nature of the short-hard γ-ray bursts”, Nature, October 6, 2005

2. Berger et al. “A merger origin for short γ-ray bursts inferred from the afterglow and host galaxy of GRB 050724”, Nature, November, 2005

3. Kulkarni “Modeling Macronovae”

4. Kulkarni et al. “Constraints on supernova-like emission associated with the short-hard gamma-ray burst 050509b

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Toward the SHB Progenitor: Redux• How far away are they?• How much energy do they release?

– is the energy release isotropic or collimated?– are the central engines long or short-lived?– Is there associated non-relativistic ejecta?

• What are the progenitors?– Clue (macro) = host galaxy + offset– Clue (micro) = circumburst environment

The key to answering these questions has been the precise positions enabled by the discovery of long-lived afterglows.

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GRB 050509B: Swift Detection

• BAT: very faint GRB• XRT: T+62 s detects 11

photons(!)• No optical, no radio.

very faint limits– Low energy event and/or

low density medium?

• Giant elliptical galaxy in cluster. z=0.22 Host?

Geh

rels

et a

l. 20

05

T90=40 ms

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Bloom et al. 2005

NSC J123610+285901 z=0.225

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HST Imaging: No Supernova

Kulkarni et al. 2005 Error radius = 9.3 arcsec 4 HST EpochsMay 14 to June 10

48 sources in XRT error circle

Giant elliptical Bloom et alL=1.5L*

SFR<0.1 M yr-1

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GRB 050709: HETE Detection

• A Hard spike, 84 keV• A Soft (PL) bump

(alpha=-2)• Roughly equal energy

in each component

Vil

lase

nor

et a

l. 20

05

T90=70 ms

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GRB 050709: Accurate Localization

Fox et al. 2005

SXCc

GRB QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

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HST imaging & search for supernova explosion

Fox et al. 2005

QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

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GRB 050709: Panchromatic Studies

• X-ray– source “flares” for initial 6 ks

of 18 ks in second epoch• Long-lived central engine?

– early and late flux do not fit

• Optical– inconsistent with simple PL

decay (slope=-1.3 --> -2.8)– “jet” break at T+10 d – SN limits MR>-12 mag

• Radio– violate simple AG model

Fox et al. 2005; Hjorth et al. 2005

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GRB 050724: Swift Detection

• Brightest Swift SHB• Hard spike/soft bump• X-ray, optical and radio

afterglow detected

Bar

thel

my

al. 2

005

T90=40 ms

15-150 keV

15-25 keV

T90=3 s250 ms

100 s

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Berger et al. 2005

GRB 050724: Swift

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Red ellipticalz=0.258L=1.6 L*

SFR<0.03 M yr-1

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Toward the SHB Progenitor

• How far away are they?– At least some short bursts are z ~ 0.2

• How much energy do they release?– About 1049 to 1050 erg– Evidence for ``jets’’

• Is there an associated supernova explosion?– Supernova, if any, are faint (Mv > -13)

• What are they?– Both elliptical and star-forming host galaxies

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Comparison to Long Duratrion Gamma-ray Bursts

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Empirical Connection to Ia Supernovae

Nakar & Gal-Yam

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Binary Coalescence

1

Collapsar

Magnetar

1

1 1 1

Energy Density Host Offset No SNe

1

1 0 00

0

1

0 0

1

The Score Card

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Holy smokes, he is dead?!!

Ph: Glendinning

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Coalescence of Neutron Stars (Shibata)

QuickTime™ and aYUV420 codec decompressor

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Black Hole-Neutron Star (Rupert, Janka)

QuickTime™ and aYUV420 codec decompressor

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Macronova

• Is there a sub-relativistic explosion accompanying short hard bursts?

Li & Paczynski 1998

• If so, (observationally)> Nova< Supernova

=> “Mini-supernova” or “Macronova” Kulkarni

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Macronova Model

• Parameters: Mejecta & v=c

• Composition– Free Neutrons– Radioactive Nickel– Neutron Rich Material (non-radioactive)

• Injection of energy essential for macronova to shine and be detectable

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Nickel Decay

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r-process and s-process elements

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Comparison to Data (GRB 050509b)

=0.5

=0.05

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The Macronova as a Reprocessor

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Quasars: A Historical Analogy, II

• Scintillation: Interplanetary Scintillation showed that quasars were compact

• The Central Engine: After three decades we have a working model involving black holes

• The Pesky Jets: Questions remain– FRI and FRII– What is the difference between radio quiet and radio loud AGN?

• Unification: The desire to unify various classes of quasars drove much of quasar research.

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Quasars: A Historical Analogy, I

• Astonished & Impressed: The immense power and energy of quasars resulting from Schmidt’s discovery of redshift.

• Amused and Educated: Relativistic effects such as super-luminal motion were anticipated by Rees.

• Ruthless Exploitation: Ask not why quasars quase but simply use them as light beacons to study the IGM.

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The Macronova as a reprocessor

•Long lived central soure (e.g. magnetar)•Long lived accretion disk

There are already indications of tremendous late time activity.

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SHBs Observational Milestones

• 050509B– rapid arcsecond (+/-9.3”) localization of X-ray emission (AG?)– tentative host is elliptical galaxy in merging cluster (z=0.225) – macronova and SNe limits

• 050709 – sub-arcsecond position of X-ray afterglow– unambiguous identification of spiral host galaxy & redshift (z=0.16)– discovery of optical afterglow– evidence that outflows are jet-like– evidence that central engines remain active for days to weeks

• 050724 – discovery of first radio afterglow– unambiguous identification of red elliptical host galaxy (z=0.257)

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Coalescence --> Black Hole (Shibata)

QuickTime™ and aYUV420 codec decompressor

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Gal Yam

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Possible SHB Progenitors

• Magnetar – Highly magnetized young neutron star (1014-1015 G)– Crustal breaking and magnetic reconnection = hyper-flares – short (0.2 s) hard pulse and long (300 s), soft pulse– Dominant timescale is Alfven velocity in NS

• Collapsar– Massive star core collapses to black hole + short-lived accretion disk– Nicely explains long-soft bursts– Dominant timescale is set by jet propagation in CO core (20 s)– Shorter timescales = collimated jet that wanders due to instabilities

• Binary Coalescence– Merging compact remnants (WD, NS, & BH) – Hypercritical accretion onto a newly formed BH– Dominant timescale is set by accretion disk viscosity

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58/47Taken from K.Thorne NSF Review talk

• Widely expected based on burst brightness distribution – <V/Vmax>=0.39+/0.02

– luminosity similar to long bursts but duration 100x less

– predicts faint AG

• Future z distribution will constrain merger timescale

• Tavnir et al (astro-ph) suggests 5-25% SHB are at d<100 kpc

• Good news for GW detectors like LIGO

Guetta & Piran (2005)SF + delay

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GRB/Host Offset Distributions• Offsets are notoriously

difficult to calculate. – Binary synthesis models– Galactic population of

binaries

• Depends on…– Merger times (0.1-100 Gyrs)– Proper motions (50-500 km/s)– Host galaxy potential– Binary evolution theory

• Future offsets can help constrain all of above

Fryer, Woosley & Hartmann 1999

Col

laps

ar

NS/

NS

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GRB 050709: Optical AfterglowPr

ice

et a

l. 20

05 a

nd H

jort

h et

al 2

005

T+1.42 d T+2.39 d ΔT

Decays as t-1.3

1.5m Danish Telescope, La Silla

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GRB 050724: Gemini Spectra

Prochaska et al. ; Berger et al. 2005

z=0.257

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Palomar 60-inch: Now a robotic telescope