Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 0910.2492

Distance Measurements from Supernovae and Dark Energy Constraints

Yun Wang
View original source ↗Read source document ↗Export metadata ↓

Abstract

Constraints on dark energy from current observational data are sensitive to how distances are measured from Type Ia supernova (SN Ia) data. We find that flux-averaging of SNe Ia can be used to test the presence of unknown systematic uncertainties, and yield more robust distance measurements from SNe Ia. We have applied this approach to the nearby + SDSS +ESSENCE +SNLS +HST set of 288 SNe Ia, and the ``Constitution''of set 397 SNe Ia. Combining the SN Ia data with CMB data from WMAP five year observations, the Sloan Digital Sky Survey baryon acoustic oscillation measurements, the data of 69 gammay-ray bursts, and the Hubble constant measurement from the HST project SHOES, we measure the dark energy density function X(z)=ρ_X(z)/ρ_X(0) as a free function of redshift (assumed to be a constant at z>1 or z>1.5). Without flux-averaging of SNe Ia, the combined data using the ``Constitution'' set of SNe Ia seem to indicate a deviation from a cosmological constant at ~95% confidence level at 0< z <0.8; they are consistent with a cosmological constant at ~68% confidence level when SNe Ia are flux-averaged. The combined data using the nearby +SDSS +ESSENCE +SNLS +HST data set of SNe Ia are consistent with a cosmological constant at 68% confidence level with or without flux-averaging of SNe Ia, and give dark energy constraints that are significantly more stringent than that using the ``Constitution'' set of SNe Ia. Assuming a flat universe, dark energy is detected at >98% confidence level for z<= 0.75 using the combined data with 288 SNe Ia from nearby + SDSS+ ESSENCE +SNLS +HST, independent of the assumptions about X(z>1). We quantify dark energy constraints without assuming a flat universe using the dark energy Figure-of-Merit (FoM) for both $X(z)$ and a dark energy equation-of-state linear in the cosmic scale factor.

Explore related subjects

astro-ph.COgr-qchep-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Yun Wang. 2009-11-10. Distance Measurements from Supernovae and Dark Energy Constraints. https://doi.org/10.1103/physrevd.80.123525

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Constraining spinning primordial black holes with interstellar dust heating

Primordial black holes (PBHs) are a well-motivated dark matter candidate, and their cosmic abundance is constrained by a variety of observational probes. PBHs in the mass range $10^{15}\,\text{g}\,{-}\,10^{17}\,\text{g}$ are evaporating today via Hawking radiation, a process that can heat interstellar dust and modify its thermal emission. Recent studies have used this effect to place constraints on the abundance of non-spinning PBHs. We extend this approach by investigating the influence of PBH spin on dust-heating constraints. Furthermore, we account for secondary photons that originate not only from the decay of gauge bosons but also from the decay of hadrons produced via the fragmentation of primary quarks and gluons emitted through Hawking radiation. By comparing the dust heating rate induced by spinning PBHs with the maximum cooling rate of dust, considering both silicate and graphite grains, we derive new upper limits on the fraction of dark matter in the form of PBHs, $f_{\rm PBH}$. Our results show that the constraints depend on both PBH mass and spin. Smaller PBHs with higher spin yield stronger limits. For example, in the cases we investigated, the strongest constraint is $f_{\rm PBH} \sim 1.5 \times 10^{-4}$ for $M_{\rm PBH} = 10^{15}{\rm g}$ and spin parameter $a_{*} = 0.9999$. Although these limits are less stringent than existing constraints in the same mass range, they provide a distinct and complementary approach to constraining the abundance of PBHs.

astro-ph.CO↗
arXiv2026

Two-parameter continuous deformation of Starobinsky inflation as a bridge between Planck and ACT DESI data with $N_\star\in(50,60)$

We present a family of plateau-type inflationary potentials, eq.~\eqref{Vgeneral}, and analyze a two-parameter $\alpha\beta$-Starobinsky specialization that interpolates continuously between a \emph{maximal} plateau ($V\!\to\!V_0$) and a \emph{submaximal} plateau ($V\!\to\!V_\infty 0$ with $x_\star\gg 1/\beta$ the slow-roll scaling laws change to $n_s\simeq 1-\frac{4}{3N_\star},\, r\simeq\mathcal{C}(\alpha,\beta)\,N_\star^{-4/3},$ with an explicit coefficient $\mathcal{C}(\alpha,\beta)$ set by the plateau truncation. This deformation lifts $n_s$ at fixed $N_\star$ while further suppressing $r$, reconciling the Planck~2018 constraint $n_s=0.9649\pm0.0042$ (68\% CL) and BICEP/Keck18 data $r_{0.05}<0.036$ (95\% CL), with the higher central values $n_s\sim0.97$--$0.98$ preferred by ACT+DESI~DR2 (BAO), within the theoretically motivated interval $N_\star\in(50,60)$ and without exotic reheating. We provide an exact identity for $V/V'$ enabling analytic control of $N_\star$, a practical crossover criterion $\beta\,x_\star\ll1$ vs.\ $\gg1$, and a transparent mapping between $(\alpha,\beta)$ and the observables $(n_s,r,N_\star)$. These yield sharp, testable signatures, particularly the softened $N_\star$-scaling of $r$, that distinguish a maximal from a submaximal plateau with upcoming CMB and LSS data.

astro-ph.CO↗
arXiv2026

A Tale of Two Gauges: Effective Field Theory for Relativistic Behavior of Cosmological Axions

In this work, we present a formalism to model the relativistic behavior of axions. The relativistic behavior of axions is surprisingly difficult to model precisely, as it involves oscillations on timescales much shorter than the Hubble timescale. To overcome this challenge, one typically resorts to some form of effective treatment, focusing only on the time-averaged description of the exact oscillations. Salehian, Namjoo & Kaiser provide a systematic framework for such treatment, based on the effective field theory formalism. While the aforementioned study was formulated for axion perturbations in the Newtonian gauge with no anisotropic stress, we extend the formalism to the synchronous gauge that is more conventionally used for numerical implementation in a realistic cosmological setting. Unlike their work, however, we propose a fluid interpretation in which the axion field can be identified as a perfect fluid at all times, both in the exact and effective regimes. Moreover, we present the effective field theory for the Newtonian gauge with non-zero anisotropic stress, making the original formulation more general and useful for scenarios where the matter content of the universe is multi-component. These results lay the theoretical foundation for a companion paper where we discuss how the axion field should be incorporated alongside other species in common cosmological Boltzmann solvers.

astro-ph.CO↗