The early universe up to Z 〜 6 was observed through many methods including the 3 K microwave background. How to study a SFR at the early universe beyond.

The early universe up to Z 〜 6 was observed throughmany methods including the 3 K microwave background.

How to study a SFR at the early universe beyond this ?

T. Murakami Faculty of Science , Kanazawa University920-1192 Kakuma Kanazawa Ishikawa

Exploring the early universe using GRBs

This is my plan to study and not a firm conclusion, still preliminary

The early universe at Z 〜 1000 was really observed with 3 K and give us fruitful informations. However this is only in the radiation field!

ｚ〜１０ は ALMA で確実に出来る。

King`s road to explore the objects at z〜 10 will be in infrared satellites : SIRTIF and the ALMA at sub-millimeter wave band. ALMA willbe at 〜 2010.

The most recent NASA WMAP satellite

２度

Type-Ia SNEs were used as thestandard candle.

Micro-lensing

SDSS is trying to detect remote objectsThe most distant QSO is known at z=6.6 but the number counting of the QSOs was up to 3

SDSS

How observed up to ｚ〜 6 part-1 ？

SNe

Ferguson et al. Ann. Rev. A&A 2001

How SFR was studied up to ｚ〜 4 part-2？

The background flux level in optical and UV bands were studied and used to estimate the above SFR at the early universe up to z〜 5 based on the Hubble data. However it is very hard to explore beyond this to z〜 10 in this method due to scattering or absorption.

In optical and UVSF R

Ferguson et al. Ann. Rev. A&A 2001

HDFV~30mag

Present methods cannot tell us andestimate a SFR beyond z〜 6.

ALMA can do but in 〜 2010

Gamma-ray bursts are the brightest explosions in the universe.We can observe the explosions up to z〜 10 and more.

In fact, the most distant one ever recorded was its distance is z=4.5

Z=1.6Z=3.4

Roughly ~10 GRBs are known their red-shift.The most distant one was ~4.5These GRBs were rather bright.

There are more than 3000 GRBs without known distances in the BATSE catalog.

If we can give distances to the dim member, we may estimate a SFR at z~10 with.

Using the 10 GRBs with the known distances, we can give distances to the rest of un-known GRBs.

There is a correlation between HR and the reported Z

相関係数 : Cp=0.94 　　 P(N,Cp) = 0.0015この相関は信頼度は高くないが関係を直線とする

Using the 10 GRBs with the known distances, we can give distances to the rest of un-known GRBs.

There is a correlation between HR and the reported Z

相関係数 : Cp=0.94 　　 P(N,Cp) = 0.0015この相関は信頼度は高くないが関係を直線とする

HR=0.254(z+1)+0.668

How to give distances to dim GRBs ? These are hardness ratios and Ep

€

E p ∝ L1/2

L.Amati et al., Astroph/0205230Wei, D.M. 2003

Murakami, Yonetoku, Izawa 2002

Ep

Norris et al. ApJ 534, 248, 2000

Fenimore et al., Astroph/0004176

lag

€

L=4πDL2Fγ

Lag and variability are other methods to estimate

Spectral lag-luminosity relation Ioka, Nakamura, 2001, ApJL 554, L163

We know now, GRBs are beaming. thus to estimate more precise distances, we requirethe beaming angles and also viewing directions

Murakami, Yonetoku, Izawa 2003

la g

1+z/ （ 1-cosθ ）

OT decay light curve

We can estimate beaming angle,but

Using the HR-distance formula found between HRs and the distances, we gave distance to 344 dim GRBs and plot their distributions.

data: 344

z<0  are within statistical fluctuation．

€

L=4πDL2Fγ

logN(L)-logL

We have divided the GRBs into 5 groups in distance and estimated a volume density of the GRB explosion in unit of comoving volume and time

Then produce logN-logL plots for each group and then adjust them to align a smooth line.

1

5

2

There are differences between each curve

How estimate a rate of GRBs

Based on the HR-distance relation, lags and variability-luminosity relation, we can estimate GRB rates up to z〜10. However we don’t know the fraction of GRB rate within the SFR.

C~0.94P(N,C)~0.15%

Murakami et al., 2002 in preparation

There is a small discrepancy between the SFR derived from the UV and GRBs

Madau plot 1996

Ferguson et al .2000.

Fenimore et al., Astroph/0004176

We estimated a SFR with GRBs in two independent methods. There is no clear saturation in SFR in GRBs but there is a tendency of saturation or decrease in optical data.

calorimeterXRS: 0.1~10 keV HXD:10-1000 keV

XIS 0.1-10 keV

Fully dedicated for quick GRB localizations will be launched in late 2003.We are waiting for quick and accurate locations

We require more distant GRBs to conclude.Future missions and future activity

Swift

ASTRO-E II

€

ΔE ~10eV

Astro-E II is the wide band and high qualitySpectroscopy mission and will be in 2005

IntegralLaunched in October

To determine the distances, based on the future GRB satellite, infrared observation will be a key inportant. The Lyman alpha shift to 1 micron in case of z=10. So many are planning to observedGRBs in infrared cooperating SWIFT

1.3mφ

Cooled NICMOS

Lyman break

GRBs can study a SFR up to ｚ〜 10,but still need a calibration at z =5-7.

X-ray flashes or X-ray rich GRBs are Mysterious.

Short duration GRBs (1/3) are also anotherMonster hidden from us.

These GRBs might open new understandingof an early universe