the gamma ray burst hubble diagram to z 6 6 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
THE GAMMA-RAY BURST HUBBLE DIAGRAM TO z=6.6 PowerPoint Presentation
Download Presentation
THE GAMMA-RAY BURST HUBBLE DIAGRAM TO z=6.6

Loading in 2 Seconds...

play fullscreen
1 / 21

THE GAMMA-RAY BURST HUBBLE DIAGRAM TO z=6.6 - PowerPoint PPT Presentation


  • 104 Views
  • Uploaded on

 PLOT DISTANCE vs. REDSHIFT  SHAPE OF PLOT  EXPANSION HISTORY OF UNIVERSE  SHAPE DEPENDS ON DARK ENERGY and HOW IT CHANGES. THE GAMMA-RAY BURST HUBBLE DIAGRAM TO z=6.6. Brad Schaefer Louisiana State University. HUBBLE DIAGRAMS.  1997: Perlmutter et al. 1997, ApJ, 483, 565

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'THE GAMMA-RAY BURST HUBBLE DIAGRAM TO z=6.6' - erek


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
the gamma ray burst hubble diagram to z 6 6
PLOT DISTANCE vs. REDSHIFT

SHAPE OF PLOT EXPANSION HISTORY OF UNIVERSE

SHAPE DEPENDS ON DARK ENERGY and HOW IT CHANGES

THE GAMMA-RAY BURST HUBBLE DIAGRAM TO z=6.6

Brad Schaefer

Louisiana State University

HUBBLE DIAGRAMS

sn hubble diagrams
1997: Perlmutter et al. 1997, ApJ, 483, 565

— 7 SNe at z>0.35

— Consistent with Flat & W=1

1998/9: Perlmutter et al. 1999, ApJ, 517, 565

Riess et al. 1998, AJ, 116, 1009

— 42 & 16 SN 0.16<z<0.83

— Universe will expand forever

— Expansion is accelerating

— “Dark Energy” is ‘pushing’

2004: Riess et al. 2004, ApJ, 607, 665

— 10 SNe at 1<z<1.76 with HST

— DecelerationAcceleration at z~0.46

2005: Astier et al. 2005, ApJ, 607, 665

— 71 SNe at z<1

— w=-1.023±0.090

— No constraint on change of w

2012?: http://snap.lbl.gov/

— ~2000 SNe at z<1.7

SN HUBBLE DIAGRAMS

WHAT IT TOOK TO CONVINCE THE COMMUNITY:

 Duplication by other groups

 Deep search for problems and complexities

 Confirmation by other methods

sn hubble diagrams3
1997: Perlmutter et al. 1997, ApJ, 483, 565

— 7 SNe at z>0.35

— Consistent with Flat & W=1

1998/9: Perlmutter et al. 1999, ApJ, 517, 565

Riess et al. 1998, AJ, 116, 1009

— 42 & 16 SN 0.16<z<0.83

— Universe will expand forever

— Expansion is accelerating

— “Dark Energy” is ‘pushing’

2004: Riess et al. 2004, ApJ, 607, 665

— 10 SNe at 1<z<1.76 with HST

— DecelerationAcceleration at z~0.46

2005: Astier et al. 2005, ApJ, 607, 665

— 71 SNe at z<1

— w=-1.023±0.090

— No constraint on change of w

2012?: http://snap.lbl.gov/

— ~2000 SNe at z<1.7

What is the expansion

history for z>1.7?

SN HUBBLE DIAGRAMS

WHAT IT TOOK TO CONVINCE THE COMMUNITY:

 Duplication by other groups

 Deep search for problems and complexities

 Confirmation by other methods

calibration of six luminosity indicators
CALIBRATION OF SIX LUMINOSITY INDICATORS

SPECTRAL LAG VARIABILITY PEAK PHOTON ENERGY

TIME OF JET BREAK MINIMUM RISE TIME NUMBER OF PEAKS

THEORETICAL LIMIT

slide6
PRIOR WORK:

Author (Reference) # GRBs # Lum Ind.

Schaefer (2001, three public talks) 8 GRBs 2 (tlag,V)

Schaefer (2003, ApJLett, 583, 67) 9 GRBs 2 (tlag,V)

Bloom et al. (2003, ApJ, 594, 674) 16 GRBs 1 (tbreak)

Xu, Dai, Liang (2005, ApJ, 633, 603) 17 GRBs 1 (tbreak)

Firmani et al. (2005, MNRAS, 360, 1) 15 GRBs 1 (tbreak)

Liang & Zhang (2005, ApJ, 633, 611) 15 GRBs 1 (tbreak)

Schaefer (This work)60 GRBs 5 (tlag,V,Ep, tbreak, trise)

THIS WORK:

 60 GRBs

 27 with z>2, 14 with z>3, 6 with z>4, and 2 with z>6

 26 with SWIFT, 16 with HETE, 8 with BATSE, 6 with KONUS, 3 with SAX, 1 with INTEGRAL

 Combine information from all 5 luminosity indicators to get best luminosity

 Must simultaneously fit cosmology and luminosity relations

GRB HUBBLE DIAGRAM

(Schaefer 2003)

slide7
ACCURACY FOR INDIVIDUAL SNe & GRBs:

µ (overall)

OBJECT Median Best

SNe*0.23 mag 0.15 mag

GRB 0.60 mag 0.21 mag

*Gold & Silver sample from Riess et al. (2004 ApJ, 607, 665)

SN ADVANTAGES: GRB ADVANTAGES:

 2.6X more accurate singly  Uniquely covers 1.7< z < 6.6

 Physics of SNe is well known No problem from extinction (or Ly-a clouds)

 Results are ‘free’ and now

SN & GRB COMPARISON

One SN is on average 2.6x

more accurate than one GRB

slide8

60 GRB HUBBLE DIAGRAM

‘Standard’ cosmology:

Flat Universe with WM=0.27±0.04,

Cosmological Constant [w=-1 and unchanging for w=P/rc2]

slide9

8 NEW GRBs SINCE JANUARY

‘Standard’ cosmology:

Flat Universe with WM=0.27±0.04,

Cosmological Constant [w=-1 and unchanging for w=P/rc2]

slide10

DERIVED DISTANCES DEPEND LITTLE ON ASSUMED COSMOLOGY

‘Standard’ cosmology [WM=0.27, Flat Universe, w0 = -1, w= 0]

versus

Best Fit cosmology [WM=0.27, Flat Universe, w0 = -1.4, w = 1.3]

slide11

60 GRB HUBBLE DIAGRAM

‘Standard’ cosmology:

Flat Universe with WM=0.27±0.04,

Cosmological Constant [w=-1 and unchanging for w=P/rc2]

slide12

APPEARS TO BE FLAT AT z>2.5

‘Standard’ cosmology:

Flat Universe with WM=0.27±0.04,

Cosmological Constant [w=-1 and unchanging for w=P/rc2]

slide13

APPEARS TO BE FLAT AT z>2.5

‘Standard’ cosmology:

Flat Universe with WM=0.27±0.04,

Cosmological Constant [w=-1 and unchanging for w=P/rc2]

slide14

SEARCH FOR BEST COSMOLOGY

Assume Flat Universe, marginalize over WM

Assume Equation of state; w=P/rc2, let w vary as w0+wz or w0+wa*z/(1+z)

Cosmological Constant has w=-1 and w=wa=0

w = w0 + w zw = w0+wa*z/(1+z)

Cosmological Constant at 2.8s level Cosmological Constant at 2.3s level

slide15

WHAT IS BEST WM?

Assume Flat Universe with w0 = -1.4 and w = 1.3

One Sigma: 0.25< WM <0.59

slide16

SEARCH FOR BEST COSMOLOGY

Assume Flat Universe with WM=0.27±0.04,

w = w0 + w zw = w0+wa*z/(1+z)

Cosmological Constant rejected at 3.5s level Cosmological Constant rejected at 3.7s level

slide17

BEST FIT COSMOLOGY

Best Fit cosmology:

Flat Universe with WM=0.27±0.04,

w0 = -1.4, w=dw/dz = 1.3, w=P/rc2=w0+wz

first results from new method
 GRB HUBBLE DIAGRAM FLATTENS FOR z>2.5:

Best fit has w0 = -1.4 and w = 1.3

Cosmological Constant rejected at 3.5s level

In good agreement with Gold & Silver SNe

If Dark Energy changes with time, then it is not vacuum energy

FIRST RESULTS FROM NEW METHOD
questions potential problems
 MALMQUIST BIAS:

Very difficult problem to calculate, because conditions for detecting burst as a function of redshift are highly inhomogenous and not well known

 GRAVITATIONAL LENSING AMPLIFICATION AND DEAMPLIFICATION BY FOREGROUND GALAXIES:

Any resulting bias is likely to be insignificant (Daniel Holz 2005)

 WHAT ARE THE IMPLICATIONS FOR STAR FORMATION IMPLIED BY A FLATTENED HUBBLE DIAGRAM?

Is such a flattening consistent with what we know?

 WHAT ARE EFFECTS OF EVOLUTION?

I claim the effects will be near-zero because the GRB luminosity indicators

are based on quantities like conservation of energy in jet and light travel

time, and these do not evolve with time or metalicity; while it does not

matter if the typical luminosities change with time so long as the

calibration of the relations is based on the physics of the situation.

QUESTIONS & POTENTIAL PROBLEMS
future
 FIRST RESULT MUST BE CHECKED WITH INDEPENDENT SAMPLE OF GRBs:

HETE & SWIFT will get ~60 more GRBs with redshifts in ~2 years

 FIRST RESULTS MUST SURVIVE SCRUTINY, IMPROVEMENTS, AND PROBLEMS:

Many people need to examine this from many directions

 FIRST RESULT MUST BE CONFIRMED/DENIED BY INDEPENDENT METHODS:

Perhaps with lensing or quasars…

FUTURE
conclusions
 NEW METHOD TO MEASURE DARK ENERGY:

Unique information for 1.7< z < 6.6

 FIRST RESULTS:

60 GRBs from 0.2< z < 6.6

 HUBBLE DIAGRAM FLATTENS

FOR z>2.5:

Dark Energy changes over time,

(Cosmological Constant rejected at 3.5s)

or Hi-z GRBs are brighter by ~3X

(Malmquist bias?)

 THIS RESULT MUST BE CONFIRMED OR DENIED BY INDEPENDENT STUDY:

Independent GRB data

(60 more HETE & SWIFT bursts)

Independent methods

(perhaps lensing or quasars...)

CONCLUSIONS