We study frequentist confidence intervals based on graphical profile likelihoods (Wilks’ theorem, likelihood integration), and the Feldman–Cousins (FC) prescription, a generalisation of the Neyman belt construction, in a setting with non-Gaussian Markov chain Monte Carlo (MCMC) posteriors. Our simplified setting allows us to recycle the MCMC chain as an input in all methods, including mock simulations underlying the FC approach. We find all methods agree to within $$10 \%$$ in the close to Gaussian regime, but extending methods beyond their regime of validity leads to greater discrepancies. As a key consistency check, we recover a shift in cosmological parameters between low and high redshift cosmic chronometer data with the FC method, but only when one fits all parameters back to the mocks. We observe that fixing parameters, a common approach in the literature, risks underestimating confidence intervals.

India

Shubham Barua

Shantanu Desai

Ireland

Mexico

Mauricio Lopez-Hernandez

Eoin Ó Colgáin

On frequentist confidence intervals in a non-Gaussian regime

In this work, we test the cosmic distance duality relation (CDDR) using the arbitrary redshift pivot Padé-(2,1) expansion methodology developed in Ref Fazzari et al. . This approach allows us to constrain the cosmography parameters and test the CDDR at any redshift. Further, it does not rely on data reconstructions or extrapolations of the cosmography parameters to higher redshifts. We employ observational data from the Dark Energy Spectroscopic Instrument (DESI) Baryon Acoustic Oscillation dataset, cosmic chronometers (CC), and Type Ia supernovae from the Pantheon Plus (PP) and Dark Energy Survey Year 5 (DESY5) compilations. We find no significant deviations from the standard CDDR relation in the range $$0\lesssim z \lesssim 1$$ when considering DESI $$+r_d$$ dataset in combination with PP+CC and DESY5+CC datasets. However, on imposing a Gaussian prior on $$M_B \in \mathcal {N}(-19.253, 0.027)$$ (instead of treating it as a free parameter) in the dataset combination PP+CC, we find CDDR violation at a level of $$(3-5)\sigma .$$

Sujit Dalui

Japan

Rikiya Okazaki

Testing the cosmic distance duality relation using model-independent approach

We apply data-motivated priors on the peak absolute magnitude of Type Ia supernovae ($\textit{M}$) and the sound horizon at the drag epoch ( $$r_d$$ ), $$ M-r_d$$ We use the data from Pantheon $$+$$ , Cosmic Chronometers, and the results for this purpose. We reaffirm the fact that there is a degeneracy between $\textit{M}$ and $$r_d$$ , and modifying the $$r_d$$ values to reconcile the also requires a change in the peak absolute magnitude $\textit{M}$. For certain $\textit{M}$ and $$r_d$$ priors, the is found to reduce to be as low as (1.2–2) $$\sigma $$ $$\Lambda $$ . We also notice that for our datasets considered, the Gaussian prior combination of $$M \in \mathcal {N} (-\,19.253,0.027)$$ (obtained from SH0ES) and $$r_d \in \mathcal {N} (147.05,0.3)$$ Mpc (determined from Planck CMB measurements) is least favored as compared to other prior combinations for the $$\Lambda $$ CDM model.

Effect of peak absolute magnitude of Type Ia supernovae and sound horizon values

We reanalyze the spectral lag data for GRB 160625B using frequentist inference in order to constrain the energy scale $$(E_{QG})$$ of Lorentz Invariance Violation (LIV). For this purpose, we use profile likelihood to deal with the astrophysical nuisance parameters. This is in contrast to Bayesian inference implemented in previous works, where marginalization was carried out over the nuisance parameters. We show that with profile likelihood, we do not find a global minimum for $$\chi ^2$$ as a function of $$E_{QG}$$ below the Planck scale for both linear and quadratic models of LIV, whereas bounded credible intervals were previously obtained using Bayesian inference. Therefore, we can set one-sided lower limits in a straightforward manner. We find that $$E_{QG} \ge 2.55 \times 10^{16}$$ GeV and $$E_{QG} \ge 1.85 \times 10^7$$ GeV at 95% c.l., for linear and quadratic LIV, respectively. Therefore, this is the first proof-of-principles application of profile likelihood method to the analysis of GRB spectral lag data to constrain LIV.

United States

Shalini Ganguly

Constraint on Lorentz invariance violation for spectral lag transition in GRB 160625B using profile likelihood

We search for a redshift dependence of  $$\sigma _8^0$$  <math> <msubsup> <mi>σ</mi> <mn>8</mn> <mn>0</mn> </msubsup> </math>   using 23 growth rate measurements from redshift space distortions and peculiar velocity measurements as a consistency check of  $$\Lambda $$  <math> <mi>Λ</mi> </math>  CDM. For this purpose we use the dataset from Sagredo et al. (Phys Rev D 98:083543, 2018) consisting of 22 measurements, which has been vetted for internal consistencies. Eighteen of these measurements have been obtained from the Gold-2017 sample, collated from multiple redshift space distortion surveys between 2009 and 2016, whereas the remaining four have been obtained from the eBOSS DR14 quasar survey. We also added one additional data point from the BOSS DR12 CMASS galaxy sample. We find that for this dataset the  $$\sigma _8^0$$  <math> <msubsup> <mi>σ</mi> <mn>8</mn> <mn>0</mn> </msubsup> </math>   values are consistent between the low redshift and high redshift samples using three different redshift cuts. This implies that the growth rate measurements are consistent with a constant  $$\sigma _8^0$$  <math> <msubsup> <mi>σ</mi> <mn>8</mn> <mn>0</mn> </msubsup> </math>   in accord with  $$\Lambda $$  <math> <mi>Λ</mi> </math>  CDM, assuming there are no uncontrolled systematics in this dataset.

Siddhant Manna

A test for the redshift dependence of  $$\sigma _8$$  <math> <msub> <mi>σ</mi> <mn>8</mn> </msub> </math>   using  $$f\sigma _8$$  <math> <mrow> <mi>f</mi> <msub> <mi>σ</mi> <mn>8</mn> </msub> </mrow> </math>   measurements

We apply the generalized Lomb–Scargle periodogram to 22 years data of solar  $$^{8}$$  <math> <msup> <mrow></mrow> <mn>8</mn> </msup> </math>  B neutrino fluxes detected by Super-Kamiokande. The primary motivation of this work was to check if the sinusoidal modulation at a frequency of 9.43/year (with a period of 38 days), which we had found to be marginally significant with the first 5 years of Super-K data, persists, with the accumulated data. We use four different metrics for the calculation of significance of any peaks in the Lomb–Scargle periodogram, which could be indicative of periodicities. We do not find any evidence for periodicity at the aforementioned frequency or any other frequency with the updated data. Therefore, the observed peak at 9.43/year with the first 5 years of Super-Kamiokande data was only a statistical fluctuation and its significance is negligible with the updated data.

Vibhavasu Pasumarti

Generalized Lomb–Scargle analysis of 22 years of super-Kamiokande solar  $$^8$$  <math> <msup> <mrow></mrow> <mn>8</mn> </msup> </math>  B neutrino data

We use a Bayesian regression technique (similar to a recent analysis by Rinaldi et al.) to obtain a central estimate for the W-boson mass using four different combinations of datasets compiled by the PDG including the 2022 CDF result. We use three different priors on the unknown intrinsic scatter and also a non-parametric hierarchical Dirichlet Process Gaussian Mixture model to obtain a world average for W-boson mass. We also evaluate the statistical significance of the discrepancy with respect to the Standard model for each of the datasets. We find that for all the combination of datasets and the aformentioned prior choices, the discrepancy with respect to the Standard Model value for the W-mass is less than 3 $$\sigma $$  <math> <mi>σ</mi> </math>  . We also checked that if we use a narrow prior on the intrinsic scatter, we get a discrepancy of about 3.8 $$\sigma $$  <math> <mi>σ</mi> </math>   compared to the Standard model value.

Aaseesh Rallapalli

Bayesian inference of W-boson mass

We use the spectral lag catalog of 46 short GRBs aggregated by Xiao et al. (Astrophys J Lett 924:L29, 2022), to carry out an independent search for Lorentz invariance violation (LIV). For this purpose, we use a power-law model as a function of energy for the intrinsic astrophysical induced spectral lags. The expansion history of the universe needed for constraining LIV was obtained in a non-parametric method using cosmic chronometers. We use Bayesian model comparison to determine if the aforementioned spectral lags show evidence for LIV as compared to only astrophysically induced lags. We do not find any evidence for LIV, and obtain 95% CL lower limits on the corresponding energy scale to be  $$4 \times 10^{15}$$  <math> <mrow> <mn>4</mn> <mo>×</mo> <msup> <mn>10</mn> <mn>15</mn> </msup> </mrow> </math>   GeV and  $$6.8 \times 10^{9}$$  <math> <mrow> <mn>6.8</mn> <mo>×</mo> <msup> <mn>10</mn> <mn>9</mn> </msup> </mrow> </math>   GeV for the linear and quadratic LIV models respectively. Our results obtained by using the flat  $$\Lambda $$  <math> <mi>Λ</mi> </math>  CDM model for characterizing the cosmic expansion history are consistent with those obtained using chronometers.

Rajdeep Agrawal

Germany

Haveesh Singirikonda

Search for Lorentz invariance violation using Bayesian model comparison applied to Xiao et al. GRB spectral lag catalog

In this work, we discuss a new method to probe the redshift evolution of the gas depletion factor, i.e. the ratio by which the gas mass fraction of galaxy clusters is depleted with respect to the universal mean of baryon fraction. The dataset we use for this purpose consists of 40 gas mass fraction measurements measured at  $$r_{2500}$$  <math> <msub> <mi>r</mi> <mn>2500</mn> </msub> </math>   using Chandra X-ray observations, strong gravitational lensing sub-samples obtained from SLOAN Lens ACS + BOSS Emission-line Lens Survey (BELLS) + Strong Legacy Survey SL2S + SLACS. For our analysis, the validity of the cosmic distance duality relation is assumed. We find a mildly decreasing trend for the gas depletion factor as a function of redshift at about 2.7 $$\sigma $$  <math> <mi>σ</mi> </math>  .

Brazil

R. Holanda

Kamal Bora

A test of the evolution of gas depletion factor in galaxy clusters using strong gravitational lensing systems

In this paper, we implement a test of the standard law for the dark matter density evolution as a function of redshift. For this purpose, only a flat universe and the validity of the FRW metric are assumed. A deformed dark matter density evolution law is considered, given by  $$\rho _c(z) \propto (1+z)^{3+\epsilon }$$  <math> <mrow> <msub> <mi>ρ</mi> <mi>c</mi> </msub> <mrow> <mo>(</mo> <mi>z</mi> <mo>)</mo> </mrow> <mo>∝</mo> <msup> <mrow> <mo>(</mo> <mn>1</mn> <mo>+</mo> <mi>z</mi> <mo>)</mo> </mrow> <mrow> <mn>3</mn> <mo>+</mo> <mi>ϵ</mi> </mrow> </msup> </mrow> </math>  , and constraints on  $$\epsilon $$  <math> <mi>ϵ</mi> </math>   are obtained by combining the galaxy cluster gas mass fractions with cosmic chronometers measurements. We find that  $$\epsilon =0$$  <math> <mrow> <mi>ϵ</mi> <mo>=</mo> <mn>0</mn> </mrow> </math>   within 2 $$\sigma $$  <math> <mi>σ</mi> </math>   c.l., in full agreement with other recent analyses.