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Luigi Piro, A. Corsi, M. Del Santo IASF-INAF Rome

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12/4/09. ESTREMO/WFXRT: WHIM WG. Luigi Piro, A. Corsi, M. Del Santo. IASF-INAF Rome ... Simulations of WHIM absorption features from OVII as expected from ... – PowerPoint PPT presentation

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Title: Luigi Piro, A. Corsi, M. Del Santo IASF-INAF Rome


1
Luigi Piro, A. Corsi, M. Del SantoIASF-INAF Rome
ESTREMO/WFXRT Tomography of WHIM with GRB
2
Dark matter WHIM X-ray forest
Structure simulation from Cen Ostriker (1999)
?
Simulations of WHIM absorption features from OVII
as expected from filaments (at different z, with
EW0.2-0.5 eV from Hellsten et al 98) in the
l.o.s. toward a GRB with Fluence4 10-6 as
observed with ESTREMO-WFXRT (in 100 ksec). About
10 of GRB (10 events per year per 3sr).
3
Summary
  • Updated simulations (from Viel, Branchini et al)
    incorporating OVII and OVIII
  • Number distribution of bright GRBs

4
Absorption from simulations
  • 5 LOS, including T, Z,n, Transmission in OVII and
    OVIII vs z. Examples

OVII
OVII
LOS5
LOS3
OVIII
OVIII
5
Single Line properties
  • Analysis of the brightest (EWgt0.1 eV) lines

6
Distribution
  • 1 filament with EWgt0.2eV (100 km/s) in OVII upto
    z0.33 (i.e. 3 per unit z). Expected from Viel et
    al (2003) 1 per unit z. From Hellsten about 12
    per unit z.
  • 1 filament with EWgt0.4eV (100 km/s) in OVIII
    upto z0.33. From Viel lt0.1 per unit redshift.
    From Hellsten et al about 1 per unit z
  • The same filament gives OVIII line with about
    twice the EW of OVII. Due to higher T (upto log
    T6.7) vs Hellsten

7
Cen 05
8
Simulations
  • A routine for including the model in XSPEC has
    been developed. It is now available on the web
    page (tested for XSPEC11). Multiplicative model.
    The user can select the LOS and OVII or OVIII or
    both (by applying the model twice)
  • Convolved with 2eV resolution matrix (updated)
    and 1 eV resolution (preliminary need to
    decrease the bin size, currently at 1 eV)

9
Simulation I
  • 2eV res. S1e-6 S4e-6
    erg cm-2

10
Simulation II
  • 1eV res. S1e-6 S4e-6
    erg cm-2

11
WHIM absorption features line _at_0.5 keV on a
background GRB afterglow
Counts NFI-TES (0.1-10 keV) Cts/eV _at_0.5 keV EWmin (eV) _at_0.5 keV
2 x 105 533 0.3
2.6 x 106 3750 0.1
5.4 x 106 7500 0.08
logFx _at_11hrs PGRB with F ?Fx N GRB per yr for FOV3sr Fx_at_60s (erg/cm2/s) Fluence (tgt60s) (erg/cm2)
-12.25 42 30 2.4 x 10-9 4 x 10-7
-11.4 8 10 1.7 x 10-8 3 x 10-6
-11.1 3 3 3.3 x 10-8 6 x 10-6
12
How many afterglows?
  • We are interested in the logN-log S of afterglows
    (Sfluence).
  • Method 1 (best) derive it directly from
    afterglow observations
  • Method 2 adopt an afterglow-to-prompt ratio and
    use the logN-logS of the prompt
  • 2a use the prompt X ((better than gamma-rays
    because stronger correlation with X-ray
    afterglow)
  • 2b use the prompt gamma (logN log S better
    sampled vs prompt X)

13
How many afterglows II
  • We have adopted method 1 (using BSAX and SWIFT
    data) and method 2a
  • Compare with 2b by Fabrizio (afterglow estimated
    at 30s)

14
X-ray afterglow fluence distribution BeppoSAX
results
N GRB per yr for FOV3sr
105
20
8
logFx _at_11hrs PGRB with F ?Fx Fx_at_60s (erg/cm2/s) Fluence (60 s lt t lt 60 ks) (erg/cm2)
-12.25 42 2.4 x 10-9 4 x 10-7
-11.4 8 1.7 x 10-8 3 x 10-6
-11.1 3 3.3 x 10-8 6 x 10-6
N GRB per yr for FOV3sr
30
10
3
1000 GRB yr-1
Using the mean value for the ratio prompt X-ray
fluence / X-ray afterglow flux _at_ 11 hrs and the
WFC logN-logS, we can compute the number of
bursts per yr observable with a FOV of 3sr
15
Is Swift confirming BeppoSAX results on the
afterglow fluence distribution?
Log(Fx) _at_11hrs P (NGRB with FgtFx)2
-12.25 44
-11.4 14
-11.1 2
SWIFT BeppoSAX
SWIFT BeppoSAX
42
8
3
t (s)
600 74
6000 84
60000 96
t (s)
600 50
6000 75
60000 87
2fraction of GRB with an afterglow flux larger
the Fx in a sample of 36 SWIFT GRBs (OBrien et
al. 2006)
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