Gammaray Bursts: A New Probe for Dark Energy

1
Gamma-ray Bursts A New Probe for Dark Energy?

• Yongzhong Xu
• T-8
• with Salman Habib

2
Dark Energy

• What is dark energy?
• Dark energy was measured by WMAP, SDSS and SN Ia
  70 substance is dark energy
• Can we do better?

3
SN Ia as a Probe

• luminous
• standard candle
• Cosmologically originated

4
Gamma-ray Bursts VS. SN Ia

• More luminous (1053 erg/s)
• Cosmologically originated (proved by GRB
  afterglows z up to 4.5)
• Standard Candle?

5
GRB Absolute Luminosity

• L as a function of Variability (Fenimore
  Ramirez-Ruiz 2000)
• L/d? 3.1 ? 1056 V3.35 ergs-1
• L as a function of spectra lag ? (Norris, Marani
  Bonnell 2000)
• L 1.3 ? 1053(?/0.01)-1.14

6
GRB dL-z relation
Data from Schaefer 2003
7
Constraints on ?? and ?m
8
SN Ia as a Probe

• luminous
• standard candle
• Cosmologically originated

9
Constraints on H0
10
Conclusions

• Long duration GRBs probably are good distance
  indicator
• Long duration GRB can be another probe for dark
  energy, dark matter besides SN Ia
• SWIFT will provide a more accurate answer.