Properties and Origins of Long GRBs

1
Part I

• Properties and Origins of Long GRBs

2
The Origin of Long-Period GRBs

• Knicole Colón
• High Energy Astrophysics
• March 5, 2008

3
Long-Period GRBs

• Standard total energy gt 1051 ergs
• Bursts last for t gt 2 sec (longest known has
  t2000 sec)
• Have associated X-ray, optical, and radio
  afterglows
• XRFs are similar to long GRBs but extend to
  softer, fainter regime (exact connection is still
  uncertain)

(Aurore Simonnet SSU NASA E/PO)
4
Long-Period GRBs

• Located near center of SFRs in host galaxies at
  lt z gt 2.3 (from Swift observations)
• Hosts are late-type, mostly irregular, dwarf
  galaxies
• Some are found to be associated with luminous
  core-collapse Type Ic SNe

5

• (Gehrels Cannizzo 2007)

6
Swift Observations

• Swift carries 3 instruments
• Burst Alert Telescope (BAT)
• X-Ray Telescope (XRT)
• UV-Optical Telescope (UVOT)
• (Data from http//swift.gsfc.nasa.gov/docs/swift/s
  wiftsc.html)

• As of March 4, 2008, 299 GRBs have been detected
  by Swift
• 82 GRBs have both XRT and UVOT detections
• 18 also have radio detections

7
BAT Light Curves
(From http//swift.gsfc.nasa.gov/docs/swift/swifts
c.html)
8
Long GRB X-Ray Afterglows

• (Gehrels 2008)

9
A Canonical X-Ray Afterglow Light Curve

• (Zhang 2007)

10
Optical Afterglows

• (Price et al. 2003)

11
Radio Afterglows
Radio
X-ray
Optical

• (Pihlström et al. 2007)

(Willingale et al. 2004)
12

• How do these afterglows relate to the origins of
  long duration GRBs?
• What else does the GRB-SNe relation tell us about
  the progenitors of these GRBs?

13
Single Stars as Progenitors

• Long GRBs associated with core collapse of
  massive Wolf-Rayet stars
• Collapse yields stellar-size BHs or rapidly
  spinning, highly magnetized neutron stars
• Infalling material forms a torus around central
  compact object
• Subsequent accretion of material in the torus
  fuels gamma-ray jet
• Internal shocks within gamma-ray jet and external
  shocks with residual wind material result in GRBs
  (or XRFs) and the afterglows
• (Note the Cannon Ball Model will not be taken
  into account here)

14
Collapsar (or Fireball) Model

• (From www.oamp.fr)

15
Evidence for GRB-SNe Connection

• Four direct observations of SNe associated with
  GRBs
• All SNe are confirmed as Type Ic (have no/weak H,
  He, Si II lines broad spectral lines)
• Rebrightenings detected during late stages of
  afterglows indicate SN contribution
• Most host galaxies have intense SFR

GRB050525A
(Della Valle 2008)
16
The GRB-SNe Connection
GRB-SN/HN
XRF-SN
Non-GRB HN
Normal SN

• (Nomoto et al. 2007)

17
Different Progenitors?
GRB-HNe
XRF-SNe
Non-SN GRB

• (Nomoto et al. 2007)

18
Results from Numerical Models
GRB-HNe
Non-GRB HNe/SNe
XRF-SN
Normal SN

• (Nomoto et al. 2007)

19
A Different Single Star Model

• (Yoon et al. 2008)

20
(Massive) Binary Progenitors

• Evolution of massive binaries (initial mass gt 20
  solar masses) can result in a long GRB
• Primary compact object formed works to tidally
  spin-up core of secondary star (allowing
  formation of torus after secondary collapses)
• After the GRB, a binary compact system of NS-NS,
  NS-BH, or BH-BH can remain

(Davies et al. 2007)
21
Other Binary Models

• Fryer et al. (2007) discussed the following
  possible progenitors
• Classic Binary ejection of H envelope via mass
  transfer
• Tidal Binary similar to Davies et al. (2007)
  model
• Brown Merger equal mass stars merge in second
  common-envelope phase to form single massive star
  with no H/He
• Explosive Ejection secondary accretes onto He
  core of primary, spinning up the core and also
  producing explosions in the core that eject He
  shell and H envelope
• He Merger one star evolves into NS or BH and
  then merges with companion (He-rich) star
• He case C similar to above, but merger occurs
  after He burning
• Cluster enhanced mergers that require cluster
  interactions?
• (not looked at in detail yet)

22

• (Fryer et al. 2007)

23
Conclusions

• The most likely progenitor of long-period GRBs
  isnot determined!
• Problems exist with every model!
• Many factors to consider makes solving this
  rather difficult (metallicity, initial mass,
  mass-loss rate, rotational velocity, angular
  momentum, host galaxies, properties of
  afterglows, etc.)
• There is no unified model for GRBs yet
• (and who knows if there will ever be one)

24
References

• Davies, M. B., Levan, A. J., Larsson, J., King,
  A. R., Fruchter, A. S. 2007, in AIP Conf. Proc.
  906, Gamma-Ray Bursts Prospects for GLAST, ed.
  M. Axelsson, F. Ryde, 69
• Della Valle, M. 2008, in AIP Conf. Proc. 966,
  Relativistic Astrophysics 4th Italian-Sino
  Workshop, ed. C. L. Bianco, S.-S. Xue, 31
• Fryer, C. L., et al. 2007, PASP, 119, 1211
• Gehrels, N. 2008, in AIP Conf. Proc. 968,
  Astrophysics of Compact Objects, International
  Conference on Astrophysics of Compact Objects,
  ed. Y.-F. Yuan, X.-D. Li, D. Lai, 3
• Gehrels, N., Cannizzo, J. K. 2007, in AIP Conf.
  Proc. 937, Supernova 1987A 20 Years After, ed.
  S. Immler, K. Weiler, R. McCray, 451
• Kaneko, Y., et al. 2007, ApJ, 654, 385
• Lapi, A., Kawakatu, N., Bosnjak, Z., Celotti, A.,
  Bressan, A., Granato, G. L., Danese, L. 2008,
  MNRAS, in press (astro-ph/0802.0787)
• Nomoto, K., Tominaga, N., Tanaka, M., Maeda, K.,
  Suzuki, T., Deng, J. S., Mazzali, P. A. 2007,
  Il Nuovo Cimento, in press (astro-ph/0702472)
• Pihlström, Y. M., Taylor, G. B., Granot, J.,
  Doeleman, S. 2007, ApJ, 664, 411
• Price, P. A., et al. 2003, Nature, 423, 844
• Willingale, R., Osborne, J. P., OBrien, P. T.,
  Ward, M. J., Levan, A., Page., K. L. 2004,
  MNRAS, 349, 31
• Yoon, S.-C., Langer, N., Cantiello, M., Woosley,
  S. E., Glatzmaier, G. A. 2008, in IAU Symp.
  250, Massive Stars as Cosmic Engines, ed. F.
  Bresolin, P. A. Crowther, J. Puls, in press
  (astro-ph/0801.4362)
• Zhang, B. 2007, CJAA, 7, 1

25
Part II

• Optical Afterglows of Long GRBs

26
Optical Afterglows of Long GRBs The Naked-Eye
GRB 080319B

• Knicole Colón
• High Energy Astrophysics
• April 30, 2008

Image Credit NASA, ESA, N. Tanvir (University of
Leicester), and A. Fruchter
27
A Brief Review of Long GRBs

• Total E? gt 1051 ergs
• Duration gt 2 sec (longest known has t2000 s)
• Have associated X-ray, optical, and radio
  afterglows
• Located near center of SFRs in mostly late-type,
  irregular, dwarf galaxies

• Single Star Progenitors Collapsar/Fireball Model
• Definite associations with luminous core-collapse
  Type Ic SNe
• Massive Binary Progenitors Several Models!
• No other conclusions

(Gehrels Cannizzo 2007)
28
Optical Afterglows

• Synchrotron emission resulting from a
  relativistic expanding jet colliding with ambient
  medium
• Continuous transfer of energy to swept-up medium
  and shock front physics (reverse/forward) yield
  power-law decaying curves
• Two components
• counterpart emission tracks prompt gamma-rays
• afterglow emission starts during prompt phase or
  shortly after and dims progressively for hours to
  days
• Light curves contaminated by host galaxy light,
  SN bumps

GRB050525A
(Della Valle 2008)
29
Early Afterglows

• At early times (30-104 s after trigger), behavior
  is different in different bursts
• Angular structure of relativistic outflow and
  variations in observer location may account for
  diversity manifested by early light curves

• (Panaitescu Vestrand 2008)

30
Late Afterglows

• Late time behavior includes
• 1. Jet Breaks (sudden increase of the fading
  rate due to jet geometry, typically few days
  after initial GRB)

3. SN bumps
2. Flares
(Dai et al. 2008)
31
Overall Afterglow Behavior

• Narrow/Clustered bimodal distribution of optical
  afterglow luminosity
• Intrinsic?
• 60 of bursts are absorbed by large amount (gt 1.5
  mag) of gray dust?
• Clear separation between luminous and
  sub-luminous families

(Nardini et al. 2008)
32

• Knowing all of this about optical afterglows
  where does GRB 080319B fit in?

33
The Naked-Eye GRB 080319B

• GRB duration 60 sec
• Gamma-Ray E 1054 erg
• V 5.6 mag (Mpeak -38.0)
• z 0.937 (relatively nearby)
• At 10 kpc, would peak at V -28.5
• Highest-fluence event isotropic-equivalent
  energy release ever recorded

Swifts XRT UVOT Images
Image Credit NASA/Swift/Stefan Immler, et al.
(Bloom et al. 2008)
Animation Credit Pi of the Sky
34
Brightest Optical Afterglow Ever!

• Fast-rising afterglow
• Early afterglow decays extremely rapidly (drops
  from 5th to 21st mag in lt 1 day)
• 2 short-timescale flares
• Smooth AG overall (note that many GRBs show
  significant jaggedness)

(Bloom et al. 2008)
35

• Rather unremarkable at late times
• Similar to 3 other ultra-luminous GRBs

• Late time afterglow
• No jet break seen
• Occurred extremely early (within first 100 sec)?
  
• Early rapid decay reverse-shock dominated, jet
  break hidden in transition region around 103 sec?
• Second scenario brought on by extreme level of
  collimation

(Bloom et al. 2008)
36
Fits Cannon Ball Model?

• Ordinary GRB produced by jet of highly
  relativistic plasmoids (CBs) ejected in
  core-collapse SN
• Viewed very near axis of CB-emission
• Generated by typical GRB SNe, SN1998bw? Or
  most-luminous one detected, SN2006gy?

(Dado et al. 2008)
37
Results (?)

• Bloom et al. (2008) conclude the extreme
  brightness is related to macroscopic parameters
  of central engine (primarily collimation angle
  maybe also Mejecta, initial Lorentz factor,
  circumburst medium?) rather than extrema in shock
  parameters
• Similarly, Dado et al. (2008) claim cannon ball
  model fits (but this model is not as widely
  accepted by GRB community fire ball model
  dominates)
• Also claim AG properties fit those of other
  AG/GRBs associated with typical SN (remains to
  be seen)
• Final Fun Fact disregarding absorption, this GRB
  would be observable even if placed at the epoch
  of reionization!

38
References

• Bloom, J.S., et al. 2008, astro-ph/0803.3215
• Dado, S., Dar, A., De Rujula, A. 2008,
  astro-ph/0804.0621
• Dai, X., et al. 2007, astro-ph/0712.2239
• Della Valle, M. 2008, in AIP Conf. Proc. 966,
  Relativistic Astrophysics 4th Italian- Sino
  Workshop, ed. C. L. Bianco, S.-S. Xue, 31
• Gehrels, N., Cannizzo, J. K. 2007, in AIP Conf.
  Proc. 937, Supernova 1987A 20 Years After, ed.
  S. Immler, K. Weiler, R. McCray, 451
• Nardini, M., Ghisellini, G., Ghirlanda, G.
  2008, MNRAS, 386, L87
• Panaitescu, A., Vestrand, W. T. 2008,
  submitted to MNRAS, astro-ph/0803.1872
• Uemura, M., et al. 2003, astro-ph/0306396