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Hunting down horizon-scale effects with multi-wavelength surveys

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arxiv 1507.04605 v2 pith:TQFJHHY4 submitted 2015-07-16 astro-ph.CO gr-qc

classification astro-ph.COgr-qc
keywords surveyseffectscosmichorizon-scalelargevariancewillassumed
verification ladder T0 review T1 audit T2 compute T3 formal
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abstract

Next-generation cosmological surveys will probe ever larger volumes of the Universe, including the largest scales, near and beyond the horizon. On these scales, the galaxy power spectrum carries signatures of local primordial non-Gaussianity (PNG) and horizon-scale general relativistic (GR) effects. However, cosmic variance limits the detection of horizon-scale effects. Combining different surveys via the multi-tracer method allows us to reduce the effect down cosmic variance. This method benefits from large bias differences between two tracers of the underlying dark matter distribution, which suggests a multi-wavelength combination of large volume surveys that are planned on a similar timescale. We show that the combination of two contemporaneous surveys, a large neutral hydrogen intensity mapping survey in SKA Phase1 and a Euclid-like photometric survey, will provide unprecedented constraints on PNG as well as detection of the GR effects. We forecast that the error on local PNG will break through the cosmic variance limit on cosmic microwave background surveys and achieve $\sigma(f_{NL})\simeq1.4-0.5$, depending on assumed priors, bias, and sky coverage. GR effects are more robust to changes in the assumed fiducial model, and we forecast that they can be detected with a signal-to-noise of about $14$.

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Forward citations

Cited by 6 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. OpenAlex reports about 116 citations worldwide. Full citation record

  1. Complex yet Hermitian: Gaussian covariance of cross-correlation and multi-tracer power spectra

    astro-ph.CO 2026-06 unverdicted novelty 7.0 of 10

    A general analytical expression for the Gaussian covariance of complex multi-tracer power spectra is derived, applied to multipoles and 2D spectra, and validated against Monte Carlo simulations.

  2. Primordial non-Gaussianity -- the effects of relativistic and wide-angle corrections to the power spectrum

    astro-ph.CO 2024-12 conditional novelty 5.0 of 10

    Including the quadrupole in power-spectrum forecasts improves f_NL precision by 45% to 63%, while neglected relativistic and wide-angle corrections shift f_NL by up to 0.6 sigma for MegaMapper.

  3. Probing primordial non-Gaussianity by reconstructing the initial conditions

    astro-ph.CO 2024-12 conditional novelty 5.0 of 10

    Applying a hybrid reconstruction, then cross-correlating the squared potential with the density, yields a simulated f_NL forecast up to three times tighter than the unreconstructed bispectrum.

  4. Cosmology with HI Intensity Mapping

    astro-ph.CO 2026-07 accept novelty 4.0 of 10

    SKAO HI intensity mapping forecasts yield competitive LambdaCDM constraints (e.g. H0 to ~0.3 km/s/Mpc optimistic) via power spectrum, BAO, bispectrum and stacking, complementary to CMB and optical surveys.

  5. Beyond {\Lambda}CDM with the SKA Observatory -- II: Unveiling the Secrets of the Early Universe

    astro-ph.CO 2026-07 accept novelty 3.5 of 10

    Updated SKAO-AA4 forecasts show multi-tracer HI+galaxy analyses can reach σ(f_local_NL)≲1 and improve αs bounds by tens of percent when combined with future CMB, while foregrounds and GR light-cone effects remain the ...

  6. Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies

    astro-ph.CO 2022-03 accept novelty 2.0 of 10

    The paper reviews cosmological tensions including the H0 and S8 discrepancies and explores new physics models that could explain them.

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