Detection of gravitational lensing in the cosmic microwave background

By Kendrick M. Smith, Oliver Zahn, O. Doré. 2007

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Gravitational lensing of the cosmic microwave background (CMB), a long-standing prediction of the standard cosmological model, is ultimately expected to be an important source of cosmological information, but first detection has not been achieved to date. We report a 3.4{sigma} detection, by applying quadratic estimator techniques to all sky maps from the Wilkinson microwave anisotropy probe (WMAP) satellite, and correlating the result with radio galaxy counts from the NRAO VLA sky survey (NVSS). We present our methodology including a detailed discussion of potential contaminants. Our error estimates include systematic uncertainties from density gradients in NVSS, beam effects in WMAP, galactic microwave foregrounds, resolved and unresolved CMB point sources, and the thermal Sunyaev-Zel'dovich effect.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0ed2daf9eb921ebcb65eebef8053816b579f458b

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Citations in the corpus

Gravitational lensing (2010, background): “So far, there are no published direct detections of CMB lensing, but there is indirect evidence with significance around 3-σ obtained by cross-correlating the CMB with different samples of distant foreground sources used for tracing the potentially lensing large-scale structure [190, 460].”
Small scale problems of the $\Lambda$CDM model: a short review (2016, background): “, lensing of the CMB [6,7], B-mode polarisation [8] the kinetic SZ effect) — it presents several difficulties.”
The Atacama Cosmology Telescope: temperature and gravitational lensing power spectrum measurements from three seasons of data (2013, background): “Signatures of CMB lensing were ﬁrst observed in correlations of the CMB with large-scale struc-18 S. Das et al. ture (Smith et al. 2007; Hirata et al. 2008).”
SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) OBSERVATIONS: COSMOLOGICAL INTERPRETATION (2010, methodology): “The C−1 matrix is computed by the multigrid-based algorithm of Smith et al. (2007).”
Delensing CMB polarization with external datasets (2010, methodology): “Lens reconstruction from temperature has been applied to detect CMB lensing in WMAP, in crosscorrelation with large-scale structure [46, 47] and is expected to be a powerful source of cosmological information in the near future [48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59].”
A MEASUREMENT OF THE DAMPING TAIL OF THE COSMIC MICROWAVE BACKGROUND POWER SPECTRUM WITH THE SOUTH POLE TELESCOPE (2011, methodology): “Previous efforts to detect lensing of the CMB include ∼3σ detections from correlating quadratic reconstructions of the lensing field from the CMB with other mass tracers (Smith et al. 2007; Hirata et al. 2008), .”
Observational probes of cosmic acceleration (2012, methodology): “The signal was detected three years later with combinations of SDSS and NVSS data, and two additional years of WMAP data (Smith et al., 2007; Hirata et al., 2008).”
Primordial Non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Structure (2010, methodology): “in [81], in order to compute the C−1a prefiltering in reasonable CPU time.”
COrE (Cosmic Origins Explorer) A White Paper (2011, background): “At the WMAP resolution and sensitivity, the reconstruction is very noisy but cross-correlation studies with galaxy surveys have led to a detection at the 3σ level [36].”
The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengths (2012, methodology): “…35 Weak lensing of CMB anisotropies by large-scale structure (LSS) has been measured on WMAP data by cross-correlation with the NRAO VLA Sky Survey (NVSS), used as a high-redshift radio galaxy catalogue (Smith et al. 2007), as well as in a combined analysis with SDDS and NVSS (Hirata et al. 2008).”
A MEASUREMENT OF GRAVITATIONAL LENSING OF THE MICROWAVE BACKGROUND USING SOUTH POLE TELESCOPE DATA (2012, methodology): “Apodization Previous work has dealt with correlations due to sky cuts by setting the noise to be large in cut pixels, and then taking the full pixel-pixel covariance matrix into account (Smith et al. 2007).”
HIGH-RESOLUTION CMB POWER SPECTRUM FROM THE COMPLETE ACBAR DATA SET (2008, methodology): “The value preferred by the WMAP5 data is slightly higher than that from WMAP3, and more consistent with that found when ACBAR is added to either WMAP data set. less than the WMAP3/NVSS/SDSS cross-correlation results of Smith et al. (2007) and Hirata et al. (2008).”
Planck2018 results (2018, methodology): “The large matrix inversion is performed with a multigridpreconditioned conjugate-gradient search (Smith et al. 2007).”