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Explore issues in ΛCDM model via sensitivity of WMAP Cosmic Microwave Background power spectrum to beam profiles. Discuss implications for simpler cosmological models and challenges in interpreting WMAP data accurately.
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Beam profile sensitivity of WMAP CMB power spectrum UtaneSawangwit & Tom Shanks Durham University
Standard CDM Model - Issues! • Dark matter – exotic particles as yet undetected! • ⇒ 1 in 10100 fine-tuning coincidence – anthropic? • Even though inflation was set up to get rid of fine-tuning! • has wrong sign for string theory – Anti-de Sitter v. de Sitter • Standard inflation model⇒10^1077 Universes! • Wrong mass function for galaxies! • Downsizing observed v. bottom-up hierarchy predicted • Feedback - more energy now used in preventing stars form than in forming them under gravity
WMAP 5-Year Power Spectrum Universe comprises: ~72% Dark Energy ~24% CDM ~4% Baryons (Hinshaw et al. 2003, 2006, 2008, Spergel et al. 2003, 2006, 2008)
Sensitivity of WMAP Cl to beam Final Cl result Raw Cl result
WMAP5 point sources • 390 sources detected (5sigma) in K/Ka/Q/V/W • Complete down to ~1Jy • 373/390 have 5GHz counterparts • Flat spectrum, <α>= -0.09 • We only use compact sources (5 GHz GB6/PMN) Wright et al. (2009)
WMAP5 Radio Source Profiles Radio sources Jupiter beam Gaussian
Potential problems with RS beam • Radio Source Clustering? • Estimate based on bright NVSS source clustering... • …suggests clustering is unlikely explanation • But what about the CMB fluctuations – Eddington effect? - referee
New: “CMB-free” point sources CMB-free WMAP5 source detection, Chen & Wright 2009
Source detection • Filter the weighted map with • (Wright et al. 2009, Tegmark et al. 1998) W V Q Ka K
WMAP5 Radio Source Profiles Radio sources Jupiter beam Gaussian
De-beamed power spectra Radio sources Jupiter Gaussian
Conclusions • CDM assumes “undiscovered physics” + very finely-tuned + problems in many other areas • Model gained overwhelming support from WMAP • But WMAP power spectra highly sensitive to beam • Radio sources indicate wider beams than expected • Systematic errors on WMAP Cl may therefore increase • May reduce constraints on simpler models
Example simpler model: low H0, baryon=1 Shanks (1985) - if Ho<40kms-1Mpc-1 then: • X-ray gas → DM in Coma, Mvir/MX =15h1.5 • Inflationary baryon=1 model in better agreement with nucleosynthesis • Light element abundances baryonh2<0.06 • baryon 1 starts to be allowed for low h • Inflation+EdS => =1 => Globular Cluster Ages of 13-16Gyr require Ho<40kms-1Mpc-1 • But the first acoustic peak is at l=330, not l=220
‘Do it Yourself’ (DIY) WMAP beam • bS(q) is the beam and bl is the beam transfer function • To get the “true” power spectrum, Cl, divide the raw power spectrum, Cl’, by bl2 • Alternatively to get the beam function bl2, divide raw by true power spectum!
Beam transfer functions • diy beam functions – divide low H0 Cl by raw WMAP Cl & square root • Power-law radio source beam fits give too much power at l>300 • Need spike in bl
Ed Witten -“Strings 2001” String theory prefers a negative (anti-de Sitter!) rather than the observed positive http://theory.tifr.res.in/strings/Proceedings/witten/22.html