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Imitating intrinsic alignments: a bias to the CMB lensing-galaxy shape cross-correlation power spectrum induced by the large-scale structure bispectrum

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Cross-correlating the lensing signals of galaxies and comic microwave background (CMB) fluctuations is expected to provide valuable cosmological information. In particular, it may help tighten constraints on parameters describing the properties of intrinsically aligned galaxies at high redshift. To...

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Hauptverfasser: Merkel, Philipp M. (VerfasserIn) , Schäfer, Björn Malte (VerfasserIn)
Dokumenttyp: Article (Journal)
Sprache:Englisch
Veröffentlicht: 04 July 2017
In: Monthly notices of the Royal Astronomical Society
Year: 2017, Jahrgang: 471, Heft: 2, Pages: 2431-2437
ISSN:1365-2966
DOI:10.1093/mnras/stx1664
Online-Zugang:Verlag, kostenfrei, Volltext: http://dx.doi.org/10.1093/mnras/stx1664
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Verfasserangaben:Philipp M. Merkel and Björn Malte Schäfer
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Zusammenfassung:Cross-correlating the lensing signals of galaxies and comic microwave background (CMB) fluctuations is expected to provide valuable cosmological information. In particular, it may help tighten constraints on parameters describing the properties of intrinsically aligned galaxies at high redshift. To access the information conveyed by the cross-correlation signal, its accurate theoretical description is required. We compute the bias to CMB lensing-galaxy shape cross-correlation measurements induced by non-linear structure growth. Using tree-level perturbation theory for the large-scale structure bispectrum, we find that the bias is negative on most angular scales, therefore mimicking the signal of intrinsic alignments. Combining Euclid-like galaxy lensing data with a CMB experiment comparable to the Planck satellite mission, the bias becomes significant only on smallest scales (ℓ ≳ 2500). For improved CMB observations, however, the corrections amount to 10-15 per cent of the CMB lensing-intrinsic alignment signal over a wide multipole range (10 ≲ ℓ ≲ 2000). Accordingly, the power spectrum bias, if uncorrected, translates into 2σ and 3σ errors in the determination of the intrinsic alignment amplitude in the case of CMB stage III and stage IV experiments, respectively.
Beschreibung:Gesehen am 17.10.2017
Beschreibung:Online Resource
ISSN:1365-2966
DOI:10.1093/mnras/stx1664

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