scholarly journals Dependence of Type Ia supernova luminosities on their local environment

2018 ◽  
Vol 615 ◽  
pp. A68 ◽  
Author(s):  
M. Roman ◽  
D. Hardin ◽  
M. Betoule ◽  
P. Astier ◽  
C. Balland ◽  
...  

We present a fully consistent catalog of local and global properties of host galaxies of 882 Type Ia supernovæ (SNIa) that were selected based on their light-curve properties, spanning the redshift range 0.01 < z < 1. This catalog corresponds to a preliminary version of the compilation sample and includes Supernova Legacy Survey (SNLS) 5-year data, Sloan Digital Sky Survey (SDSS), and low-redshift surveys. We measured low- and moderate-redshift host galaxy photometry in SDSS stacked and single-epoch images and used spectral energy distribution fitting techniques to derive host properties such as stellar mass and U − V rest-frame colors; the latter are an indicator of the luminosity-weighted age of the stellar population in a galaxy. We combined these results with high-redshift host photometry from the SNLS survey and thus obtained a consistent catalog of host stellar masses and colors across a wide redshift range. We also estimated the local observed fluxes at the supernova location within a proper distance radius of 3 kpc, corresponding to the SNLS imaging resolution, and transposed them into local U − V rest-frame colors. This is the first time that local environments surrounding SNIa have been measured at redshifts spanning the entire Hubble diagram. Selecting SNIa based on host photometry quality, we then performed cosmological fits using local color as a third standardization variable, for which we split the sample at the median value. We find a local color step significance of − 0.091 ± 0.013 mag (7σ), which effect is as significant as the maximum mass step effect. This indicates that the remaining luminosity variations in SNIa samples can be reduced with a third standardization variable that takes the environment into account. Correcting for the maximum mass step correction of − 0.094 ± 0.013 mag, we find a local color effect of − 0.057 ± 0.012 mag (5σ), which shows that additional information is provided by the close environment of SNIa. Departures from the initial choices were investigated and showed that the local color effect is still present, although less pronounced. We discuss the possible implications for cosmology and find that using the local color in place of the stellar mass results in a change in the measured value of the dark energy equation-of-state parameter of 0.6%. Standardization using local U − V color in addition to stretch and color reduces the total dispersion in the Hubble diagram from 0.15 to 0.14 mag. This will be of tremendous importance for the forthcoming SNIa surveys, and in particular for the Large Synoptic Survey Telescope (LSST), for which uncertainties on the dark energy equation of state will be comparable to the effects reported here.

2019 ◽  
Vol 28 (12) ◽  
pp. 1950154 ◽  
Author(s):  
Celia Escamilla-Rivera ◽  
Salvatore Capozziello

Constraining the dark energy equation of state, [Formula: see text], is one of the main issues of current and future cosmological surveys. In practice, this requires making assumptions about the evolution of [Formula: see text] with redshift [Formula: see text], which can be manifested in a choice of a specific parametric form where the number of cosmological parameters play an important role in the observed cosmic acceleration. Since any attempt to constrain the EoS requires some prior fixing in one form or the other, settling a method to constrain cosmological parameters is of great importance. In this paper, we provide a straightforward approach to show how cosmological tests can be improved via a parametric methodology based on cosmography. Using Supernovae Type IA samplers, we show how by performing a statistical analysis of a specific dark energy parametrization can give directly the cosmographic parameters values.


2009 ◽  
Vol 3 (1) ◽  
pp. 144-178 ◽  
Author(s):  
Christopher Genovese ◽  
Peter Freeman ◽  
Larry Wasserman ◽  
Robert Nichol ◽  
Christopher Miller

2006 ◽  
Vol 74 (8) ◽  
Author(s):  
Jun-Qing Xia ◽  
Gong-Bo Zhao ◽  
Hong Li ◽  
Bo Feng ◽  
Xinmin Zhang

2014 ◽  
Vol 29 (02) ◽  
pp. 1450008 ◽  
Author(s):  
VINCENZO SALZANO ◽  
YUN WANG ◽  
IRENE SENDRA ◽  
RUTH LAZKOZ

In this paper, we propose a test to detect the linearity of the dark energy equation of state, and apply it to the SNLS3 Type Ia Supernova (SN Ia) data set. We find that: (a) current SN Ia data are well described by a dark energy equation of state linear in the cosmic scale factor a, at least up to a redshift z = 1, independent of the pivot points chosen for the linear relation; (b) there is no significant evidence of any deviation from linearity. This apparent linearity may reflect the limit of dark energy information extractable from current SN Ia data.


2011 ◽  
Vol 7 (S281) ◽  
pp. 26-28
Author(s):  
Enikő Regős ◽  

AbstractThe nature and timescales behind the growth of the white dwarf toward the Chandrasekhar mass are not known. The two leading competing scenarios for Type Ia supernovae (SNe Ia) are accretion from a companion [single degenerate (SD)] or merger with another white dwarf [double degenerate (DD)]. Measurement of the SNe Ia delay time distribution could distinguish between these scenarios. Possibly both channels operate, on short (SD) and long (DD) time scales. A supernova search in parallel with our Cluster Lensing And Supernova survey with Hubble extends the Hubble diagram of SNe Ia to z > 1.5, probing progenitor evolution and testing the constancy of dark energy (DE) with time. We use HST ACS to detect SNe Ia at 1 < z < 1.5 and WFC3 to find SNe Ia at 1.5 < z < 2.5, thus providing constraints for the variation in the DE equation of state. This redshift epoch provides the unique chance to test SNe Ia distance measurements for the deleterious effects of evolution independent of our ignorance of dark energy. Our program provides the first measurement of the SNe Ia rate at z ~ 2.


Author(s):  
Marek Demianski ◽  
Elisabeta Lusso ◽  
Maurizio Paolillo ◽  
Ester Piedipalumbo ◽  
Guido Risaliti

2018 ◽  
Vol 616 ◽  
pp. A32 ◽  
Author(s):  
C. J. A. P. Martins ◽  
M. Prat Colomer

One of the most compelling goals of observational cosmology is the characterisation of the properties of the dark energy component thought to be responsible for the recent acceleration of the universe, including its possible dynamics. In this work we study phenomenological but physically motivated classes of models in which the dark energy equation of state can undergo a rapid transition at low redshifts, perhaps associated with the onset of the acceleration phase itself. Through a standard statistical analysis we have used low-redshift cosmological data, coming from Type Ia supernova and Hubble parameter measurements, to set constraints on the steepness of these possible transitions as well as on the present-day values of the dark energy equation of state and in the asymptotic past in these models. We have also studied the way in which these constraints depend on the specific parametrisation being used. Our results confirm that such late-time transitions are strongly constrained. If one demands a matter-like pre-transition behaviour, then the transition is constrained to occur at high redshifts (effectively in the matter era), while if the pre-transition equation of state is a free parameter then it is constrained to be close to that of a cosmological constant. In any case, the value of dark energy equation of state near the present day must also be very similar to that of a cosmological constant. The overall conclusion is that any significant deviations from this behaviour can only occur in the deep matter era, so there is no evidence for a transition associated with the onset of acceleration. Observational tools capable of probing the dynamics of the universe in the deep matter era are therefore particularly important.


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