arXiv subjects

Shouvik Roy Choudhury

Publications and source records attributed to Shouvik Roy Choudhury.

14 recordsLinked to original sources

arXiv2026

Updated 1.1% Precision Values of the Hubble Constant with Corrected Pantheon+ and Dark Energy Survey (DES)-DOVEKIE Type Ia Supernovae

We update the Hubble constant measurement with corrected Pantheon+ and DES-DOVEKIE supernovae. The use of DES-DOVEKIE here is the first application of DES-DOVEKIE to a distance-ladder $H_0$ determination. Recent reanalyses of supernova datasets have put Pantheon+, DES-DOVEKIE, and Union3.1 samples on the same footing with regard to the evidence of dynamical dark energy ($3.2$--$3.4σ$), and thus an update on the Hubble constant is the next logical step. The $H_0$ Distance Network (H0DN) baseline is $73.499\pm0.809$ km s$^{-1}$ Mpc$^{-1}$, a $7.1σ$ tension with the cosmic microwave background (CMB) determination in a $Λ$ cold-dark-matter ($Λ$CDM) cosmology, $H_0^{\rm CMB,ΛCDM}=67.24\pm0.35$ km s$^{-1}$ Mpc$^{-1}$. A revised host-mass correction applied to the older Pantheon+ changes 114 of the total 1701 apparent-magnitude rows. The calibrator supernovae are not affected, but 52 of the 277 Hubble-flow rows are. Applying only these magnitude corrections, with the H0DN covariance, redshifts, and velocities unchanged, gives $H_0=73.264\pm0.806$ km s$^{-1}$ Mpc$^{-1}$ and a $6.85σ$ Hubble tension. This is our main baseline result and the update for the astrophysics community. Alternatively, replacing the complete Hubble-flow treatment with the corrected Pantheon+ data gives $73.139\pm0.791$ km s$^{-1}$ Mpc$^{-1}$ and $6.82σ$. For DES-DOVEKIE, 220 supernovae span $0.025\le z_{\rm HD}\le0.151$ in Hubble-diagram redshift, and 196 of them overlap with corrected Pantheon+. These overlaps determine the offset used to place the public DES-DOVEKIE distance moduli on the H0DN apparent-magnitude scale. Holding this offset fixed gives $H_0=73.267\pm0.828$ km s$^{-1}$ Mpc$^{-1}$ and a $6.70σ$ tension. Extending to $z_{\rm HD}\simeq0.3$ raises $H_0$. However, both rises are smaller than the H0DN uncertainty. Neither update resolves the Hubble tension. (abridged)

astro-ph.CO↗

arXiv2026

Cosmology in Extended Parameter Space with DESI Data Release 2 Baryon Acoustic Oscillations: A 2$σ$+ Detection of Nonzero Neutrino Masses with an Update on Dynamical Dark Energy and Lensing Anomaly

We obtain constraints in a 12 parameter cosmological model using the recent Dark Energy Spectroscopic Instrument Data Release (DR) 2 Baryon Acoustic Oscillations (BAO) data, combined with cosmic microwave background (CMB) power spectra (Planck Public Release, PR, 4) and lensing (Planck PR4 + Atacama Cosmology Telescope (ACT) Data Release (DR) 6) data, uncalibrated Type Ia Supernovae (SNe) data from Pantheon+ and Dark Energy Survey (DES) Year 5 (DESY5) samples, and Weak Lensing (WL: DES Year 1) data. The cosmological model consists of six $Λ$CDM parameters, and additionally, the dynamical dark energy parameters ($w_0$, $w_a$), the sum of neutrino masses ($\sum m_ν$), the effective number of non-photon radiation species ($N_{\rm eff}$), the scaling of the lensing amplitude ($A_{\rm lens}$), and the running of the scalar spectral index ($α_s$). Our major findings are the following: i) With CMB+BAO+DESY5+WL, we obtain the first 2$σ$+ detection of a nonzero $\sum m_ν = 0.19^{+0.15}_{-0.18}$ eV (95%). Replacing DESY5 with Pantheon+ still yields a $\sim$1.9$σ$ detection. ii) The cosmological constant lies at the edge of the 95% contour with CMB+BAO+Pantheon+, but is excluded at 2$σ$+ with DESY5, leaving evidence for dynamical dark energy dataset-dependent and inconclusive. iii) With CMB+BAO+SNe+WL, $A_{\rm lens} = 1$ is excluded at $>2σ$, while it remains consistent with unity without WL data - suggesting that the existence of lensing anomaly with Planck PR4 likelihoods may depend on non-CMB datasets. iv) The Hubble tension persists at 3.6-4.2$σ$ with CMB+BAO+SNe; WL data has minimal impact.

astro-ph.CO↗

arXiv2025

Cosmological constraints on nonphantom dynamical dark energy with DESI Data Release 2 Baryon Acoustic Oscillations: A 3$σ$+ lensing anomaly

We consider a 12-parameter cosmological model with non-phantom dynamical dark energy (NPDDE), where non-phantom implies that the equation of state (EoS) of dark energy (DE), $w(z)\geq-1$ for all redshifts $z$. Thus, the DE EoS covers the parameter space corresponding to the popular single scalar-field dark energy models, i.e., Quintessence. The cosmological model comprises 6 parameters of the $Λ$-Cold Dark Matter ($Λ$CDM) model, and additionally the dynamical DE EoS parameters ($w_0$, $w_a$), the scaling of the lensing amplitude ($A_{\rm lens}$), sum of the neutrino masses ($\sum m_ν$), the effective number of non-photon relativistic degrees of freedom ($N_{\rm eff}$), and the running of the scalar spectral index ($α_s$). We derive constraints on the parameters by combining the latest Dark Energy Spectroscopic Instrument (DESI) Data Release (DR) 2 Baryon Acoustic Oscillation (BAO) measurements with cosmic microwave background (CMB) power spectra from Planck Public Release (PR) 4, CMB lensing data from Planck PR4 and Atacama Cosmology Telescope (ACT) DR6, uncalibrated Type Ia supernovae (SNe) data from the Pantheon+ and Dark Energy Survey (DES) Year 5 (DESY5) samples, and Weak Lensing (WL) data from DES Year 1. Our major finding is that with CMB+BAO+WL and CMB+BAO+SNe+WL, we find 3$σ$+ evidence for $A_{\rm lens} >1$, indicating a higher than expected CMB lensing amplitude relative to the NPDDE prediction of unity. This implies that for cosmology to accommodate realistic quintessence-like dark energy models (as opposed to unrealistic phantom DE), one would also need to explain a relatively significant presence of the lensing anomaly.

astro-ph.CO↗

arXiv2024

Updated Cosmological Constraints in Extended Parameter Space with Planck PR4, DESI Baryon Acoustic Oscillations, and Supernovae: Dynamical Dark Energy, Neutrino Masses, Lensing Anomaly, and the Hubble Tension

We present updated constraints on cosmological parameters in a 12-parameter model, extending the standard six-parameter $Λ$CDM by including dynamical dark energy (DE: $w_0$, $w_a$), the sum of neutrino masses ($\sum m_ν$), the effective number of non-photon radiation species ($N_{\rm eff}$), the lensing amplitude scaling ($A_{\rm lens}$), and the running of the scalar spectral index ($α_s$). For CMB data, we use the Planck PR4 (2020) HiLLiPoP and LoLLiPoP likelihoods, Planck PR4+ACT DR6 lensing, and Planck 2018 low-$l$ TT likelihoods, along with DESI DR1 BAO and Pantheon+ and DESY5 uncalibrated type Ia Supernovae (SNe) likelihoods. Key findings are the following: i) Contrary to DESI results, CMB+BAO+Pantheon+ data include a cosmological constant within $2σ$, while CMB+BAO+DESY5 excludes it at over $2σ$, indicating the dynamical nature of dark energy is not yet robust. Potential systematics in the DESY5 sample may drive this exclusion. ii) Some data combinations show a $1σ$+ detection of non-zero $\sum m_ν$, indicating possible future detection. We also provide a robust upper bound of $\sum m_ν \lesssim 0.3$ eV (95% confidence limit (C.L.)). iii) With CMB+BAO+SNe, $A_{\rm lens} = 1$ is included at $2σ$ (albeit not at $1σ$), indicating no significant lensing anomaly in this extended cosmology with Planck PR4 likelihoods. iv) The Hubble tension persists at $3.2$ to $3.9σ$, suggesting these simple extensions do not resolve it. v) The $S_8$ tension with DES Year 3 weak lensing is reduced to $1.4σ$, likely due to additional parameters and the Planck PR4 likelihoods.

astro-ph.CO↗

arXiv2024

First constraints on non-minimally coupled Natural and Coleman-Weinberg inflation and massive neutrino self-interactions with Planck+BICEP/Keck

In this work, for the first time in literature, we study the predictions of non-minimally coupled Natural and Coleman-Weinberg potentials in the $n_s-r$ plane, and an extended $Λ$CDM model where we include non-standard self-interactions among massive neutrinos, mediated by a heavy scalar or vector boson. Constraints were derived using the Planck 2018 + BICEP/Keck 2018 datasets along with other data. For the inflationary potentials, we consider two different formulations in gravity that are non-minimally coupled to the scalar field of the inflaton: \textit{Metric and Palatini.} We only consider the self-interaction to be present among $τ$-neutrinos and only at moderate strengths. This is because strong interactions among $τ$-neutrinos, or any strength self-interaction among electron- and muon-neutrinos, as well as any strength flavor-universal interactions, are strongly disfavoured from particle physics experiments. In terms of cosmological data, we use the latest public CMB datasets from Planck 2018 and BICEP/Keck 2018 collaborations, along with other data from CMB lensing, BAO, RSD, and SNe Ia luminosity distance measurements. We find that there are some situations where predictions from the inflationary models are ruled out at more than 2$σ$ by the minimal $Λ$CDM$+r$ model, but they are allowed in the self-interacting neutrino scenario.

astro-ph.CO↗

arXiv2024

A gravitational constant transition within cepheids as supernovae calibrators can solve the Hubble tension

Local universe measurements of the Hubble constant (H0) using SNe Ia with Cepheids as calibrators yield a value of H0 which is in tension with the value inferred from the CMB and other higher redshift probes. In ref. [1], the authors proposed a rapid transition in the value of the effective Newtonian gravitational constant G in order to alleviate the Hubble tension. The transition point was chosen so as to only affect distance estimates to Hubble flow SNe. However, in this study, the authors made the assumption that SNe Ia peak luminosity $L$ increases with Chandrashekhar mass $M_c$. This hypothesis contradicts a previous semi-analytic study of SN light curves in the presence of G-transition [2] which found that $L\propto M_c^{-0.97}$. Motivated by the results of refs. [1] and [2], we propose a hypothesis of a sudden recent change in the effective G at an epoch which corresponds to a look-back distance between $\sim$ 7 - 80 Mpc. A transition in G at these distances would affect both our estimate of the distances to Cepheids in calibrator galaxies, as well as to the Hubble flow supernovae. Upon fitting the observational data to this hypothesis, we find three interesting results: (i) we find mild evidence for a G-transition at 22.4 Mpc (73 million years ago) which is preferred (using certain estimators) by the calibrator type Ia SNe data over no G-transition, (ii) the H0 parameter inferred under this hypothesis is in good agreement with the value obtained from the CMB for a 4% larger value of G at earlier times, thus potentially resolving the Hubble tension, (iii) we obtain a fit to the scaling relationship between SN peak luminosity $L$ and Chandrasekhar mass $M_c$, as $L\propto M_c^{-1.68 \pm 0.68}$, which is in good agreement with the prediction of the theoretical study of ref. [2]. We also discuss how other probes could be used to verify this transition in the value of G.

astro-ph.CO↗

arXiv2022

Massive neutrino self-interactions and inflation

Certain inflationary models like Natural inflation (NI) and Coleman-Weinberg inflation (CWI) are disfavoured by cosmological data in the standard $Λ\textrm{CDM}+r$ model (where $r$ is the scalar-to-tensor ratio), as these inflationary models predict the regions in the $n_s-r$ parameter space that are excluded by the cosmological data at more than 2$σ$ (here $n_s$ is the scalar spectral index). The same is true for single field inflationary models with an inflection point that can account for all or majority of dark matter in the form of PBHs (primordial black holes). Cosmological models incorporating strongly self-interacting neutrinos (with a heavy mediator) are, however, known to prefer lower $n_s$ values compared to the $Λ\rm CDM$ model. Considering such neutrino self-interactions can, thus, open up the parameter space to accommodate the above inflationary models. In this work, we implement the massive neutrino self-interactions with a heavy mediator in two different ways: flavour-universal (among all three neutrinos), and flavour-specific (involving only one neutrino species). We implement the new interaction in both scalar and tensor perturbation equations of neutrinos. Interestingly, we find that the current cosmological data can support the aforementioned inflationary models at 2$σ$ in the presence of such neutrino self-interactions.

astro-ph.CO↗

arXiv2022

Neutrino mass and mass ordering: No conclusive evidence for normal ordering

The extraction of the neutrino mass ordering is one of the major challenges in particle physics and cosmology, not only for its implications for a fundamental theory of mass generation in nature, but also for its decisive role in the scale of future neutrinoless double beta decay experimental searches. It has been recently claimed that current oscillation, beta decay and cosmological limits on the different observables describing the neutrino mass parameter space provide robust decisive Bayesian evidence in favor of the normal ordering of the neutrino mass spectrum [arXiv:2203.14247]. We further investigate these strong claims using a rich and wide phenomenology, with different sampling techniques of the neutrino parameter space. Contrary to the findings of Jimenez et al [arXiv:2203.14247], no decisive evidence for the normal mass ordering is found. Neutrino mass ordering analyses must rely on priors and parameterizations that are ordering-agnostic: robust results should be regarded as those in which the preference for the normal neutrino mass ordering is driven exclusively by the data, while we find a difference of up to a factor of 33 in the Bayes factors among the different priors and parameterizations exploited here. An ordering-agnostic prior would be represented by the case of parameterizations sampling over the two mass splittings and a mass scale, or those sampling over the individual neutrino masses via normal prior distributions only. In this regard, we show that the current significance in favor of the normal mass ordering should be taken as $2.7σ$ (i.e. moderate evidence), mostly driven by neutrino oscillation data.

hep-ph↗

arXiv2022

Neutrino Properties with Ground-Based Millimeter-Wavelength Line Intensity Mapping

Line intensity mapping (LIM) is emerging as a powerful technique to map the cosmic large-scale structure and to probe cosmology over a wide range of redshifts and spatial scales. We perform Fisher forecasts to determine the optimal design of wide-field ground-based mm-wavelength LIM surveys for constraining properties of neutrinos and light relics. We consider measuring the auto-power spectra of several CO rotational lines (from J=2-1 to J=6-5) and the [CII] fine-structure line in the redshift range of $0.25<z<12$. We study the constraints with and without interloper lines as a source of noise in our analysis, and for several one- and multi-parameter extensions of $Λ$CDM. We show that LIM surveys deployable this decade, in combination with existing CMB (primary) data, could achieve order of magnitude improvements over Planck constraints on $N_{\rm eff}$ and $M_ν$. Compared to next-generation CMB and galaxy surveys, a LIM experiment of this scale could achieve bounds that are a factor of $\sim3$ better than those forecasted for surveys such as EUCLID (galaxy clustering), and potentially exceed the constraining power of CMB-S4 by a factor of $\sim1.5$ and $\sim3$ for $N_{\rm eff}$ and $M_ν$, respectively. We show that the forecasted constraints are not substantially affected when enlarging the parameter space, and additionally demonstrate that such a survey could also be used to measure $Λ$CDM parameters and the dark energy equation of state exquisitely well.

astro-ph.CO↗

arXiv2021

Updated constraints on massive neutrino self-interactions from cosmology in light of the $H_0$ tension

We have updated the constraints on flavour universal neutrino self-interactions mediated by a heavy scalar, in the effective 4-fermion interaction limit. We use the relaxation time approximation to modify the collisional neutrino Boltzmann equations, which is known to be very accurate for this particular scenario. Based on the latest CMB data from the Planck 2018 data release as well as auxiliary data we confirm the presence of a region in parameter space with relatively strong self-interactions which provides a better than naively expected fit. However, we also find that the most recent data, in particular high-$\ell$ polarisation data from the Planck 2018 release, disfavours this solution even though it cannot yet be excluded. Our analysis takes into account finite neutrino masses (parameterised in terms of $\sum m_ν$) and allows for a varying neutrino energy density (parameterised in terms of $N_{\rm eff}$), and we find that in all cases the neutrino mass bound inferred from cosmological data is robust against the presence of neutrino self-interactions. Finally, we also find that the strong neutrino self-interactions do not lead to a high value of $H_0$ being preferred, i.e.\ this model is not a viable solution to the current $H_0$ discrepancy.

astro-ph.CO↗

arXiv2020

Updated results on neutrino mass and mass hierarchy from cosmology with Planck 2018 likelihoods

In this work we update the bounds on $\sum m_ν$ from latest publicly available cosmological data and likelihoods using Bayesian analysis, while explicitly considering particular neutrino mass hierarchies. In the minimal $Λ\textrm{CDM}+\sum m_ν$ model with most recent CMB data from Planck 2018 TT,TE,EE, lowE, and lensing; and BAO data from BOSS DR12, MGS, and 6dFGS, we find that at 95\% C.L. the bounds are: $\sum m_ν<0.12$ eV (degenerate), $\sum m_ν<0.15$ eV (normal), $\sum m_ν<0.17$ eV (inverted). The bounds vary across the different mass orderings due to different priors on $\sum m_ν$. Also, we find that the normal hierarchy is very mildly preferred relative to the inverted, using both minimum $χ^2$ values and Bayesian Evidence ratios. In this paper we also provide bounds on $\sum m_ν$ considering different hierarchies in various extended cosmological models: $Λ\textrm{CDM}+\sum m_ν+r$, $w\textrm{CDM}+\sum m_ν$, $w_0 w_a \textrm{CDM}+\sum m_ν$, $w_0 w_a \textrm{CDM}+\sum m_ν$ with $w(z)\geq -1$, $Λ\textrm{CDM} + \sum m_ν + Ω_k$, and $Λ\textrm{CDM} + \sum m_ν + A_{\textrm{Lens}}$. We do not find any strong evidence of normal hierarchy over inverted hierarchy in the extended models either.

astro-ph.CO↗

arXiv2019

Constraining light sterile neutrino mass with the BICEP2/Keck Array 2014 B-mode polarization data

We explore the thermal light sterile neutrino situation from cosmological perspective in the $Λ\textrm{CDM} + r_{0.05} + N_{\textrm{eff}} + m^{\textrm{eff}}_{\textrm{s}}$ model using combinations of latest data sets available. Here, $r_{0.05}$ is the tensor-to-scalar ratio at the pivot scale of $k_*=0.05h$ Mpc$^{-1}$, $N_{\textrm{eff}}$ is the effective number of relativistic species during recombination, and $m^{\textrm{eff}}_{\textrm{s}}$ is the effective mass of the sterile neutrino. Among Cosmic Microwave Background (CMB) datasets, we use Planck 2015 temperature and low-$l$ ($l <$ 30) polarization data and the latest data release on the B-mode polarization up to and including 2014 from the BICEP2/Keck collaboration (BK14). We also use the latest BAO data from SDSS-III BOSS DR12, MGS, and 6dFS; and a Gaussian prior (HST) on the Hubble constant ($H_0 = 73.24 \pm 1.74$ km/sec/Mpc) from direct measurements. We find that inclusion of BK14 data makes the constraints on the effective mass of sterile neutrino ($m^{\textrm{eff}}_{\textrm{s}}$) slightly stronger by preferring higher $σ_8$ values. The bound of $m^{\textrm{eff}}_{\textrm{s}} <$ 0.46 eV (95\% C.L.) is found for the combination of Planck 2015, BAO and BK14 datasets, whereas the bound is $m^{\textrm{eff}}_{\textrm{s}} <$ 0.53 eV (95\% C.L.) without the BK14 data. Our most aggressive bound of $m^{\textrm{eff}}_{\textrm{s}} <$ 0.28 eV (95\% C.L.) is obtained with Planck 2015, HST and BK14. However, the HST prior also leads to very high $N_{\textrm{eff}}$ which might be in conflict with bounds from BBN. Our analysis indicates that fully thermalized sterile neutrinos with mass $\sim 1$ eV are slightly more disfavoured with the inclusion of BK14 data. It also seems to make the agreement between Planck 2015 and CFHTLenS (weak gravitational lensing data) worse due to the higher $σ_8$ values (abstract abridged).

astro-ph.CO↗

arXiv2019

Strong Bounds on Sum of Neutrino Masses in a 12 Parameter Extended Scenario with Non-Phantom Dynamical Dark Energy ($w(z)\geq -1$)

We obtained constraints on a 12 parameter extended cosmological scenario including non-phantom dynamical dark energy (NPDDE) with CPL parametrization. We also include the six $Λ$CDM parameters, number of relativistic neutrino species ($N_{\textrm{eff}}$) and sum over active neutrino masses ($\sum m_ν$), tensor-to-scalar ratio ($r_{0.05}$), and running of the spectral index ($n_{run}$). We use CMB Data from Planck 2015; BAO Measurements from SDSS BOSS DR12, MGS, and 6dFS; SNe Ia Luminosity Distance measurements from the Pantheon Sample; CMB B-mode polarization data from BICEP2/Keck collaboration (BK14); Planck lensing data; and a prior on Hubble constant ($73.24\pm1.74$ km/sec/Mpc) from local measurements (HST). We have found strong bounds on the sum of the active neutrino masses. For instance, a strong bound of $\sum m_ν <$ 0.123 eV (95\% C.L.) comes from Planck+BK14+BAO. Although we are in such an extended parameter space, this bound is stronger than a bound of $\sum m_ν <$ 0.158 eV (95\% C.L.) obtained in $Λ\textrm{CDM}+\sum m_ν$ with Planck+BAO. Varying $A_{\textrm{lens}}$ instead of $r_{0.05}$ however leads to weaker bounds on $\sum m_ν$. Inclusion of the HST leads to the standard value of $N_{\textrm{eff}} = 3.045$ being discarded at more than 68\% C.L., which increases to 95\% C.L. when we vary $A_{\textrm{lens}}$ instead of $r_{0.05}$, implying a small preference for dark radiation, driven by the $H_0$ tension.

astro-ph.CO↗

arXiv2018

Updated Bounds on Sum of Neutrino Masses in Various Cosmological Scenarios

We present strong bounds on the sum of three active neutrino masses ($\sum m_ν$) in various cosmological models. We use the following baseline datasets: CMB temperature data from Planck 2015, BAO measurements from SDSS-III BOSS DR12, the newly released SNe Ia dataset from Pantheon Sample, and a prior on the optical depth to reionization from 2016 Planck Intermediate results. We constrain cosmological parameters in $ΛCDM$ model with 3 massive active neutrinos. For this $ΛCDM+\sum m_ν$ model we find a upper bound of $\sum m_ν <$ 0.152 eV at 95$\%$ C.L. Adding the high-$l$ polarization data from Planck strengthens this bound to $\sum m_ν <$ 0.118 eV, which is very close to the minimum required mass of $\sum m_ν \simeq$ 0.1 eV for inverted hierarchy. This bound is reduced to $\sum m_ν <$ 0.110 eV when we also vary r, the tensor to scalar ratio ($ΛCDM+r+\sum m_ν$ model), and add an additional dataset, BK14, the latest data released from the Bicep-Keck collaboration. This bound is further reduced to $\sum m_ν <$ 0.101 eV in a cosmology with non-phantom dynamical dark energy ($w_0 w_a CDM+\sum m_ν$ model with $w(z)\geq -1$ for all $z$). Considering the $w_0 w_a CDM+r+\sum m_ν$ model and adding the BK14 data again, the bound can be even further reduced to $\sum m_ν <$ 0.093 eV. For the $w_0 w_a CDM+\sum m_ν$ model without any constraint on $w(z)$, the bounds however relax to $\sum m_ν <$ 0.276 eV. Adding a prior on the Hubble constant ($H_0 = 73.24\pm 1.74$ km/sec/Mpc) from Hubble Space Telescope (HST), the above mentioned bounds further improve to $\sum m_ν <$ 0.117 eV, 0.091 eV, 0.085 eV, 0.082 eV, 0.078 eV and 0.247 eV respectively. This substantial improvement is mostly driven by a more than 3$σ$ tension between Planck 2015 and HST measurements of $H_0$ and should be taken cautiously. (abstract abridged)

astro-ph.CO↗