The H I intensity mapping bispectrum including observational effects
Abstract
The bispectrum is a three-point statistic with the potential to provide additional information beyond power spectra analyses of survey data sets. Radio telescopes that broadly survey the 21-cm emission from neutral hydrogen (H I) are a promising way to probe LSS and in this work we present an investigation into the H I intensity mapping (IM) bispectrum using simulations. We present a model of the redshift space H I IM bispectrum including observational effects from the radio telescope beam and 21-cm foreground contamination. We validate our modelling prescriptions with measurements from robust IM simulations, inclusive of these observational effects. Our foreground simulations include polarization leakage, on which we use a principal component analysis cleaning method. We also investigate the effects from a non-Gaussian beam including side-lobes. For a MeerKAT-like single-dish IM survey at z = 0.39, we find that foreground removal causes an $8{{\ \rm per\ cent}}$ reduction in the equilateral bispectrum's signal-to-noise ratio, whereas the beam reduces it by $62{{\ \rm per\ cent}}$. We find our models perform well, generally providing $\chi ^2_\text{dof}\sim 1$, indicating a good fit to the data. Whilst our focus is on post-reionization, single-dish IM, our modelling of observational effects, especially foreground removal, can also be relevant to interferometers and reionization studies.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 2021
- DOI:
- 10.1093/mnras/stab2200
- arXiv:
- arXiv:2102.11153
- Bibcode:
- 2021MNRAS.507.1623C
- Keywords:
-
- methods: data analysis;
- methods: statistical;
- cosmology: observations;
- cosmology: large-scale structure of Universe;
- radio lines: general;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 19 pages, 14 figures. The main results for telescope beam and foreground effects on the bispectrum can be found in Sec 3.2 and 3.3. Minor changes to text in Version 2 in response to referee report and an amendment to Fig 12 to include more information. Version 2 accepted for publication in MNRAS