Cross-correlating the EMU Pilot Survey 1 with CMB lensing: Constraints on cosmology and galaxy bias with harmonic-space power spectra
Publications of the Astronomical Society of Australia Cambridge University Press 42 (2025) e062
Abstract:
We measured the harmonic-space power spectrum of Galaxy clustering auto-correlation from the Evolutionary Map of the Universe Pilot Survey 1 data (EMU PS1) and its cross-correlation with the lensing convergence map of cosmic microwave background (CMB) from Planck Public Release 4 at the linear scale range from to 500. We applied two flux density cuts at and mJy on the radio galaxies observed at 944MHz and considered two source detection algorithms. We found the auto-correlation measurements from the two algorithms at the 0.18 mJy cut to deviate for due to the different criteria assumed on the source detection and decided to ignore data above this scale. We report a cross-correlation detection of EMU PS1 with CMB lensing at 5.5 , irrespective of flux density cut. In our theoretical modelling we considered the SKADS and T-RECS redshift distribution simulation models that yield consistent results, a linear and a non-linear matter power spectrum, and two linear galaxy bias models. That is a constant redshift-independent galaxy bias and a constant amplitude galaxy bias . By fixing a cosmology model and considering a non-linear matter power spectrum with SKADS, we measured a constant galaxy bias at mJy ( mJy) with ( ) and a constant amplitude bias with ( ). When is a free parameter for the same models at mJy ( mJy) with the constant model we found ( ), while with the constant amplitude model we measured ( ), respectively. Our results agree at with the measurements from Planck CMB and the weak lensing surveys and also show the potential of cosmology studies with future radio continuum survey data.Cross-correlating the EMU Pilot Survey 1 with CMB lensing: Constraints on cosmology and galaxy bias with harmonic-space power spectra
Publications of the Astronomical Society of Australia (2025)
Abstract:
We measured the harmonic-space power spectrum of galaxy clustering auto-correlation from the Evolutionary Map of the Universe Pilot Survey 1 data (EMU PS1) and its cross-correlation with the lensing convergence map of cosmic microwave background (CMB) from Planck Public Release 4 at the linear scale range from ℓ = 2 to 500. We applied two flux density cuts at 0.18 and 0.4mJy on the radio galaxies observed at 944MHz and considered two source detection algorithms. We found the auto-correlation measurements from the two algorithms at the 0.18mJy cut to deviate for ℓ ≥ 250 due to the different criteria assumed on the source detection and decided to ignore data above this scale. We report a cross-correlation detection of EMU PS1 with CMB lensing at ∼5.5σ, irrespective of flux density cut. In our theoretical modelling we considered the SKADS and T-RECS redshift distribution simulation models that yield consistent results, a linear and a non-linear matter power spectrum, and two linear galaxy bias models. That is a constant redshift-independent galaxy bias b(z) = bConstraining ultra-high-energy cosmic ray composition through cross-correlations
Journal of Cosmology and Astroparticle Physics IOP Publishing 2022:12 (2022) 003
Constraining a late time transition of Geff using low-z galaxy survey data
Phys. Rev. D 106, 023526
Abstract:
It has recently been pointed out that a gravitational transition taking place at a recent redshift zt, reducing the effective gravitational constant Geff by about 10% for z>zt, has the potential to lead to a resolution of the Hubble tension if zt≲0.01. Since H(z)2∼Geff, such a transition would also lead to sharp change of the slope of the Hubble diagram at z=zt and a sharp decrease in the number of galaxies per redshift bin at zt. Here we attempt to impose constraints on such a transition by using two robust low-z redshift survey datasets (z<0.01), taken from the Six-degree Field Galaxy Survey (6dFGS) as well as the 2MASS Redshift Survey (2MRS). In both surveys, we bin the data in redshift bins and focus on the number of galaxies in each bin (ΔN(zi)). We observe a peak in the distribution of galaxies near a distance of approximately 20 Mpc in both datasets. This feature could be attributed to galactic density fluctuations, to coherent peculiar velocities of galaxies or to an ultra late-time gravitational transition in the same era. In the context of the later scenario we show that this feature could have been induced by a sharp change of Geff by ΔGeff/Geff≃0.6 at zt≃0.005. Thus, in a conservative approach, this method can be used to impose constraints on a possible abrupt change of the gravitational constant taking place at very low redshifts.
EuCAPT White Paper: Opportunities and Challenges for Theoretical Astroparticle Physics in the Next Decade
ArXiv preprint. White paper of the European Consortium for Astroparticle Theory (EuCAPT). 135 authors, 400 endorsers, 133 pages, 1382 references
Abstract:
Astroparticle physics is undergoing a profound transformation, due to a series of extraordinary new results, such as the discovery of high-energy cosmic neutrinos with IceCube, the direct detection of gravitational waves with LIGO and Virgo, and many others. This white paper is the result of a collaborative effort that involved hundreds of theoretical astroparticle physicists and cosmologists, under the coordination of the European Consortium for Astroparticle Theory (EuCAPT). Addressed to the whole astroparticle physics community, it explores upcoming theoretical opportunities and challenges for our field of research, with particular emphasis on the possible synergies among different subfields, and the prospects for solving the most fundamental open questions with multi-messenger observations.