English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The squeezed-limit bispectrum, which is generated by nonlinear gravitationalevolution as well as inflationary physics, measures the correlation of threewavenumbers, in the configuration where one wavenumber is much smaller than theother two. Since the squeezed-limit bispectrum encodes the impact of alarge-scale fluctuation on the small-scale power spectrum, it can be understoodas how the small-scale power spectrum "responds" to the large-scalefluctuation. Viewed in this way, the squeezed-limit bispectrum can becalculated using the response approach even in the cases which do not submit toperturbative treatment. To illustrate this point, we apply this approach to thecross-correlation between the large-scale quasar density field and small-scaleLyman-$\alpha$ forest flux power spectrum. In particular, using separateuniverse simulations which implement changes in the large-scale density,velocity gradient, and primordial power spectrum amplitude, we measure how theLyman-$\alpha$ forest flux power spectrum responds to the local,long-wavelength quasar overdensity, and equivalently their squeezed-limitbispectrum. We perform a Fisher forecast for the ability of future experimentsto constrain local non-Gaussianity using the bispectrum of quasars and theLyman-$\alpha$ forest. Combining with quasar and Lyman-$\alpha$ forest powerspectra to constrain the biases, we find that for DESI the expected $1-\sigma$constraint is ${\rm err}[f_{\rm NL}]\sim60$. Ability for DESI to measure$f_{\rm NL}$ through this channel is limited primarily by the aliasing andinstrumental noise of the Lyman-$\alpha$ forest flux power spectrum. Thecombination of response approach and separate universe simulations provides anovel technique to explore the constraints from the squeezed-limit bispectrumbetween different observables.

Response approach to the squeezed-limit bispectrum: application to the correlation of quasar and Lyman-$\alpha$ forest power spectrum