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TRANSCRIPT
The evolution of the cosmic UV
background at high redshifts
Lutz Wisotzki, Aldo Dall’Aglio
Astrophysikalisches Institut Potsdam
Gabor Worseck
UCO/Lick
Dall’Aglio et al 2008a, A&A 480, 359; Dall’Aglio et al 2008b, A&A 491, 465; Dall’Aglio et al 2009, in prep.
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Conclusions
I. The Proximity Effect can be employed to obtain a direct
and unbiased measurement of the UV background.
Overdensity effects are small and can be avoided.
II. The intergalactic H photoionisation rate is ∼ constant
between z ∼ 2 and z ∼ 3.2, possibly out to z ∼ 4.5
III. Starlight accounts for ∼ 100 % of the UVB at z >∼ 3;
existing surveys fall short of the measured UVB for z >∼ 4.5
IV. MUSE will uniquely probe the faint LAE population
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
fλ
λ
ω
τ/τ∞1.0
0.5
0
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
⋆
fλ
λ
ω
τ/τ∞1.0
0.5
0∞1001010.10.01
ω ≡ΓQSO(z)ΓUVB(z)
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
The proximity effect in individual quasar spectra
Dal
l’Agl
ioat
al.20
08
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Strength of the proximity effect
Q 0216+08:
Strong proximity effect
! log"< 0
QSO ‘overluminous’ or
lower absorption
Q 1451−15:
Average proximity effect! log"≈ 0
HE 0151−4326:
Weak proximity effect
! log"> 0
QSO ‘underluminous’ or
more absorption
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Proximity Effect Strength Distribution
Histogram of ∆ logω for 40 QSO spectra in UVES sample:
∆ logω Dall’Aglio at al. 2008, A&A 491, 465
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Proximity Effect Strength Distribution
Histogram of ∆ logω for 40 QSO spectra in UVES sample:
∆ logω
Monte-Carlo Simulations: Pure Shot Noise
Dall’Aglio at al. 2008
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Proximity Effect Strength Distribution
Histogram of ∆ logω for 40 QSO spectra in UVES sample:
∆ logω
Pure Shot Noise
Monte-Carlo Simulations: Pure Shot Noise
Dall’Aglio at al. 2008
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Evolution of the UV background
Dall’Aglio et al. 2008
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
The proximity effect in 2000 quasar spectra from SDSS
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
The proximity effect in 2000 quasar spectra from SDSS
PE detected in 98 % of the sample!
Dall’Aglio et al. 2009, in prep.
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Evolution of the UV background: UVES and SDSS
Dall’Aglio et al. 2008
Dall’Aglio et al. 2009, in prep.
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Comparison to Ly-forest opacity modelling
Dall’Aglio et al. 2008
Dall’Aglio et al. 2009, in prep.
Bolton et al. 2005
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Comparison to Ly-forest opacity modelling
Dall’Aglio et al. 2008
Dall’Aglio et al. 2009, in prep.
Bolton et al. 2005
Faucher-Giguerre et al. 2008
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
AGN contribution to the hydrogen photoionisation rate
Dall’Aglio et al. 2009, in prep.
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Contribution from star forming galaxies
Dall’Aglio et al. 2009, in prep.
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Contribution from star forming galaxies
Dall’Aglio et al. 2009, in prep.
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Probing the late stages of reionisation with MUSE
• Current high-z surveys only
sensitive to massive systems
• How to get deeper
and large samples?
⇒ Integral Field Spectroscopy
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
MUSE fast facts:
• 2nd gen. VLT instrument
• 1′ × 1′ field of view
0.2 arcsec spatial pixels
• Spectral resolution: 250 km/s
• AO supported
• First light in 2012
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Expectations for MUSE
Simulated MUSE Deep Field
• Ultra-Deep survey for Ly-αemitters
• at least 1000 LAE with
f > 10−18 erg s−1 cm−2
at 3 < z < 6.7
• Many constraints on LAE:
– faint end of LF
– Ly-α line profiles
– clustering of weak LAE?
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki
Conclusions
I. The Proximity Effect can be employed to obtain a direct
and unbiased measurement of the UV background.
Overdensity effects are small and can be avoided.
II. The intergalactic H photoionisation rate is ∼ constant
between z ∼ 2 and z ∼ 3.2, possibly out to z ∼ 4.5
III. Starlight accounts for ∼ 100 % of the UVB at z >∼ 3;
existing surveys fall short of the measured UVB for z >∼ 4.5
IV. MUSE will be fabulous
Reionization@Ringberg 2009 UV background at high redshifts Lutz Wisotzki