arXiv subjects

Pranjal R. S

Publications and source records attributed to Pranjal R. S.

3 recordsLinked to original sources

arXiv2026

Cosmic shear with one component and its application to future radio surveys

We present a new approach to measuring cosmic shear: the one-component kinematic lensing (KL) method. This technique provides a simplified implementation of KL that reduces shape noise in weak lensing (WL) by combining kinematic information with imaging data, while requiring less observational effort than the full two-component KL. We perform simulated likelihood analyses to assess the performance of the one-component KL and demonstrate its applicability to future radio surveys. Our forecasts indicate that, for radio surveys, the one-component KL is not yet competitive with traditional WL due to the shallow redshift distribution of Hi-selected galaxies. However, when applying this method to deeper spectroscopic surveys with stronger emission lines, the one-component KL approach could surpass WL in constraining power, offering a promising and efficient pathway for future shear analyses.

astro-ph.CO↗

arXiv2026

Baryons in the Darkest Sites of the Universe

The pristine underdense patches of the Universe, cosmic voids, are powerful cosmological laboratories, uniquely sensitive to dark energy, modified gravity, and neutrino masses, yet their baryonic content remains uncharacterized. We present the first observational constraint on baryon underdensity in void interiors, exploiting the dispersion measures (DMs) of Fast Radio Bursts (FRBs) as tracers of the free electron column, independent of gas phase, temperature, and metallicity. By stacking 3,455 sightlines from CHIME/FRB on 1,288 SDSS BOSS voids over redshifts $0.2 < z < 0.7$, we measure a DM deficit toward void centers at $3.2σ$ significance, establishing that diffuse baryons inhabit the emptiest corners of the cosmic web at a suppressed level. The measured signal amplitude is consistent with an effective Universe model built directly from the observed galaxy underdensity in these voids, and a baryonic model calibrated to the FRB DM-redshift relation ($α_v = 1.80 \pm 0.87$). A uniform-density void model yields an electron density contrast of $δ_\mathrm{e,v} = -0.58 \pm 0.30$, implying a $\sim 60$% underdensity of baryons in void interiors relative to the cosmic mean. Jointly interpreting our FRB measurement with existing stacks of the thermal Sunyaev-Zel'dovich effect on voids further constrains the mean void gas temperature to $T_\mathrm{e} \lesssim (1.1 \pm 0.7) \times 10^6$ K, pointing to a warm-hot diffuse phase, consistent with hydrodynamical simulation predictions. With forthcoming FRB (CHORD, DSA, SKA) and galaxy (DESI, LSST, Euclid, PFS-Subaru, SPHEREx, Roman) surveys, set to expand both samples by orders of magnitude, this approach opens a new window onto tomographic baryon mapping, with direct implications for feedback models governing gas expulsion into low-density environments, and for the use of cosmic voids to extract cosmological constraints.

astro-ph.CO↗

arXiv2026

Signatures of Suppressed Matter Clustering revealed by Fast Radio Bursts

Complex astrophysical processes regulate the growth of galaxies by injecting energy and momentum into their surroundings, redistributing baryons across megaparsec scales. The clustering of matter on these scales, as measured via weak lensing and galaxy surveys, encodes critical cosmological information on the dynamical dark energy, the nature of dark matter and the sum of neutrino masses. The suppression of matter clustering due to feedback processes limits the interpretation of cosmological measurements. Multiple probes of the baryon distribution have attempted to quantify the strength of feedback via measurements of suppression in the matter power spectrum. The dispersion measures (DMs) of fast radio bursts (FRBs) have emerged as a powerful new probe of baryons, with the advantage over other probes of being unbiased with respect to density and temperature. Here, we use a sample of 109 FRBs with redshifts and DMs to directly measure the spatial fluctuations in the baryon density field, quantifying the effects of feedback on the matter power spectrum at scales of $k \sim 0.1-3$ h/Mpc, and the gas fraction in galaxy groups and clusters ($10^{13}-10^{15} M_\odot$). We use a halo-model prescription to conduct inference, and find that FRB data reduces the posterior variance at k $\sim$ 1 h/Mpc by a factor of $\sim 8$ relative to the prior. The statistical precision of inferred FRB constraints is similar to other baryon tracers, while probing a complementary redshift regime ($z \lesssim 0.3$). A comparison with several hydrodynamical simulations excludes extreme large-scale feedback scenarios at $\sim 2σ$ confidence. This work establishes FRBs as a sensitive probe of feedback-regulated structure formation. As next-generation experiments deliver orders-of-magnitude larger samples, FRBs are poised to drive the constraints on baryonic physics in the era of precision cosmology.

astro-ph.CO↗