Cross-correlation of the thermal Sunyaev-Zel’dovich and CMB lensing signals in <i>Planck</i> PR4 data with robust CIB decontamination

Abstract

We use the full-mission PR4 data to measure the CMB lensing convergence (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>κ</a:mi></a:math>)–thermal Sunyaev-Zel’dovich (tSZ, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>y</c:mi></c:math>) cross-correlation signal, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msubsup><e:mi>C</e:mi><e:mo>ℓ</e:mo><e:mrow><e:mi>y</e:mi><e:mi>κ</e:mi></e:mrow></e:msubsup></e:math>. This is only the second measurement to date of this signal, following Hill and Spergel []. We perform the measurement using foreground-cleaned tSZ maps built from the PR4 frequency maps via a tailored needlet internal linear combination (NILC) code in our companion paper [F. McCarthy and J. C. Hill, companion paper, .], in combination with the PR4 <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mrow><g:mi>κ</g:mi></g:mrow></g:math> maps and various systematic-mitigated PR3 <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mrow><i:mi>κ</i:mi></i:mrow></i:math> maps. A serious systematic is the residual cosmic infrared background (CIB) signal in the tSZ map, as the high CIB—<k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>κ</k:mi></k:math> cross-correlation can significantly bias the inferred tSZ—<m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>κ</m:mi></m:math> cross-correlation. We mitigate this contamination by deprojecting the CIB in our NILC algorithm, using a moment deprojection approach to avoid leakage due to incorrect modeling of the CIB frequency dependence. We validate this method on mm-wave sky simulations. We fit a theoretical halo model to our measurement, finding a best-fit amplitude of <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>A</o:mi><o:mo>=</o:mo><o:mn>0.82</o:mn><o:mo>±</o:mo><o:mn>0.21</o:mn></o:math> (for the highest signal-to-noise PR4 <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mrow><q:mi>κ</q:mi></q:mrow></q:math> map) or <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:mi>A</s:mi><s:mo>=</s:mo><s:mn>0.56</s:mn><s:mo>±</s:mo><s:mn>0.24</s:mn></s:math> (for a PR3 <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"><u:mrow><u:mi>κ</u:mi></u:mrow></u:math> map built from a tSZ-deprojected CMB map), indicating that the data are consistent with our fiducial model within <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" display="inline"><w:mrow><w:mo>≈</w:mo><w:mn>1</w:mn><w:mtext>−</w:mtext><w:mn>2</w:mn><w:mi>σ</w:mi></w:mrow></w:math>. Although our error bars are similar to those of the previous measurement [J. C. Hill and D. N. Spergel, ], our method is significantly more robust to CIB contamination. Our moment-deprojection approach lays the foundation for future measurements of this signal with higher signal-to-noise <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline"><y:mi>κ</y:mi></y:math> and <ab:math xmlns:ab="http://www.w3.org/1998/Math/MathML" display="inline"><ab:mi>y</ab:mi></ab:math> maps from ground-based telescopes, which will precisely probe the astrophysics of the intracluster medium of galaxy groups and clusters in the intermediate-mass (<cb:math xmlns:cb="http://www.w3.org/1998/Math/MathML" display="inline"><cb:mi>M</cb:mi><cb:mo>∼</cb:mo><cb:msup><cb:mn>10</cb:mn><cb:mn>13</cb:mn></cb:msup><cb:mi>–</cb:mi><cb:msup><cb:mn>10</cb:mn><cb:mn>14</cb:mn></cb:msup><cb:msup><cb:mi>h</cb:mi><cb:mrow><cb:mo>−</cb:mo><cb:mn>1</cb:mn></cb:mrow></cb:msup><cb:msub><cb:mi>M</cb:mi><cb:mo stretchy="false">⊙</cb:mo></cb:msub></cb:math>), high-<fb:math xmlns:fb="http://www.w3.org/1998/Math/MathML" display="inline"><fb:mi>z</fb:mi></fb:math> (<hb:math xmlns:hb="http://www.w3.org/1998/Math/MathML" display="inline"><hb:mi>z</hb:mi><hb:mo>≲</hb:mo><hb:mn>1.5</hb:mn></hb:math>, c.f. <jb:math xmlns:jb="http://www.w3.org/1998/Math/MathML" display="inline"><jb:mrow><jb:mi>z</jb:mi><jb:mo>≲</jb:mo><jb:mn>0.8</jb:mn></jb:mrow></jb:math> for the tSZ auto-power signal) regime, as well as CIB-decontaminated measurements of tSZ cross-correlations with other large-scale structure probes. Published by the American Physical Society 2024

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