The Rise Time of Type Ia Supernovae from the Supernova Legacy Survey (original) (raw)
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EVOLUTION IN THE VOLUMETRIC TYPE Ia SUPERNOVA RATE FROM THE SUPERNOVA LEGACY SURVEY
The Astronomical Journal, 2012
We present a measurement of the volumetric Type Ia supernova (SN Ia) rate (SNR Ia) as a function of redshift for the first four years of data from the Canada-France-Hawaii Telescope (CFHT) Supernova Legacy Survey (SNLS). This analysis includes 286 spectroscopically confirmed and more than 400 additional photometrically identified SNe Ia within the redshift range 0.1 ≤ z ≤ 1.1. The volumetric SNR Ia evolution is consistent with a rise to z ∼ 1.0 that follows a power-law of the form (1+z) α , with α = 2.11 ± 0.28. This evolutionary trend in the SNLS rates is slightly shallower than that of the cosmic star-formation history over the same redshift range. We combine the SNLS rate measurements with those from other surveys that complement the SNLS redshift range, and fit various simple SN Ia delay-time distribution (DTD) models to the combined data. A simple power-law model for the DTD (i.e., ∝ t −β) yields values from β = 0.98 ± 0.05 to β = 1.15 ± 0.08 depending on the parameterization of the cosmic star formation history. A two-component model, where SNR Ia is dependent on stellar mass (M stellar) and star formation rate (SFR) as SNR Ia (z) = A× M stellar (z)+ B × SFR(z), yields the coefficients A = (1.9 ± 0.1) × 10 −14 SNe yr −1 M −1 ⊙ and B = (3.3 ± 0.2) × 10 −4 SNe yr −1 (M ⊙ yr −1) −1. More general two-component models also fit the data well, but single Gaussian or exponential DTDs provide significantly poorer matches. Finally, we split the SNLS sample into two populations by the light curve width (stretch), and show that the general behavior in the rates of faster-declining SNe Ia (0.8 ≤ s < 1.0) is similar, within our measurement errors, to that of the slower objects (1.0 ≤ s < 1.3) out to z ∼ 0.8.
The Astrophysical …, 2008
We present a measurement of the rate of type Ia supernovae (SNe Ia) from the first of three seasons of data from the SDSS-II Supernova Survey. For this measurement, we include 17 SNe Ia at redshift z ≤ 0.12. Assuming a flat cosmology with Ω m = 0.3 = 1 − Ω Λ , we find a volumetric SN Ia rate of [2.93 +0.17 −0.04 (systematic) +0.90 −0.71 (statistical)]×10 −5 SNe Mpc −3 h 3 70 year −1 , at a volumeweighted mean redshift of 0.09. This result is consistent with previous measurements of the SN Ia rate in a similar redshift range. The systematic errors are well controlled, resulting in the most precise measurement of the SN Ia rate in this redshift range. We use a maximum likelihood method to fit SN rate models to the SDSS-II Supernova Survey data in combination with other rate measurements, thereby constraining models for the redshift-evolution of the SN Ia rate. Fitting the combined data to a simple power-law evolution of the volumetric SN Ia rate, r V ∝ (1 + z) β , we obtain a value of β = 1.5 ± 0.6, i.e. the SN Ia rate is determined to be an increasing function of redshift at the ∼ 2.5σ level. Fitting the results to a model in which the volumetric SN rate, r V = Aρ(t) + Bρ(t), where ρ(t) is the stellar mass density andρ(t) is the star formation rate, we find A = (2.8 ± 1.2) × 10 −14 SNe M −1 ⊙ year −1 , B = (9.3 +3.4 −3.1 ) × 10 −4 SNe M −1 ⊙ .
The Type Ia Supernova Rate at z ≈ 0.5 from the Supernova Legacy Survey
The Astronomical Journal, 2006
We present a measurement of the distant Type Ia supernova rate derived from the first two years of the Canada -France -Hawaii Telescope Supernova Legacy Survey. We observed four one-square degree fields with a typical temporal frequency of ∆t ∼ 4 observer-frame days over time spans of from 158 to 211 days per season for each field, with breaks during full moon. We used 8-10 meter-class -2telescopes for spectroscopic followup to confirm our candidates and determine their redshifts. Our starting sample consists of 73 spectroscopically verified Type Ia supernovae in the redshift range 0.2 < z < 0.6. We derive a volumetric SN Ia rate of r V ( z = 0.47) = 0.42 +0.13 −0.09 (systematic) ±0.06 (statistical) ×10 −4 yr −1 Mpc 3 , assuming h = 0.7, Ω m = 0.3 and a flat cosmology. Using recently published galaxy luminosity functions derived in our redshift range, we derive a SN Ia rate per unit luminosity of r L ( z = 0.47) = 0.154 +0.048 −0.033 (systematic) +0.039 −0.031 (statistical) SNu. Using our rate alone, we place an upper limit on the component of SN Ia production that tracks the cosmic star formation history of 1 SN Ia per 10 3 M ⊙ of stars formed. Our rate and other rates from surveys using spectroscopic sample confirmation display only a modest evolution out to z = 0.55.
The Astrophysical …, 2010
We present a measurement of the volumetric Type Ia supernova (SN Ia) rate based on data from the Sloan Digital Sky Survey II (SDSS-II) Supernova Survey. The adopted sample of supernovae (SNe) includes 516 SNe Ia at redshift z 0.3, of which 270 (52%) are spectroscopically identified as SNe Ia. The remaining 246 SNe Ia were identified through their light curves; 113 of these objects have spectroscopic redshifts from spectra of their host galaxy, and 133 have photometric redshifts estimated from the SN light curves. Based on consideration of 87 spectroscopically confirmed non-Ia SNe discovered by the SDSS-II SN Survey, we estimate that 2.04 +1.61 −0.95 % of the photometric SNe Ia may be misidentified. The sample of SNe Ia used in this measurement represents an order of magnitude increase in the statistics for SN Ia rate measurements in the redshift range covered by the SDSS-II Supernova Survey. If we assume a SN Ia rate that is constant at low redshift (z < 0.15), then the SN observations can be used to infer a value of the SN rate of r V = (2.69 +0.34+0.21 −0.30−0.01 ) ×10 −5 SNe yr −1 Mpc −3 (H 0 /(70 km s −1 Mpc −1 )) 3 at a mean redshift of ∼ 0.12, based on 79 SNe Ia of which 72 are spectroscopically confirmed. However, the large sample of SNe Ia included in this study allows us to place constraints on the redshift dependence of the SN Ia rate based on the SDSS-II Supernova Survey data alone. Fitting a power-law model of the SN rate evolution, r V (z) = A p × ((1 + z)/(1 + z 0 )) ν , over the redshift range 0.0 < z < 0.3 with z 0 = 0.21, results in A p = (3.43 +0.15 −0.15 ) × 10 −5 SNe yr −1 Mpc −3 (H 0 /(70 km s −1 Mpc −1 )) 3 and ν = 2.04 +0.90 −0.89 .
2010
We present a measurement of the volumetric Type Ia supernova (SN Ia) rate based on data from the Sloan Digital Sky Survey II (SDSS-II) Supernova Survey. The adopted sample of supernovae (SNe) includes 516 SNe Ia at redshift z 0.3, of which 270(52%) are spectroscopically identified as SNe Ia. The remaining 246 SNe Ia were identified through their light curves; 113 of these objects have spectroscopic redshifts from spectra of their host galaxy, and 133 have photometric redshifts estimated from the SN light curves. Based on consideration of 87 spectroscopically confirmed non-Ia SNe discovered by the SDSS-II SN Survey, we estimate that 2.04 +1.61 −0.95 % of the photometric SNe Ia may be misidentified. The sample of SNe Ia used in this measurement represents an order of magnitude increase in the statistics for SN Ia rate measurements in the redshift range covered by the SDSS-II Supernova Survey. If we assume an SN Ia rate that is constant at low redshift (z < 0.15), then the SN observations can be used to infer a value of the SN rate of r V = (2.69 +0.34+0.21 −0.30−0.01)×10 −5 SNe yr −1 Mpc −3 (H 0 /(70 km s −1 Mpc −1)) 3 at a mean redshift of ∼0.12, based on 79 SNe Ia of which 72 are spectroscopically confirmed. However, the large sample of SNe Ia included in this study allows us to place constraints on the redshift dependence of the SN Ia rate based on the SDSS-II Supernova Survey data alone. Fitting a power-law model of the SN rate evolution, r V (z) = A p × ((1 + z)/(1 + z 0)) ν , over the redshift range 0.0 < z < 0.3 with z 0 = 0.21, results in A p = (3.43 +0.15 −0.15) × 10 −5 SNe yr −1 Mpc −3 (H 0 /(70 km s −1 Mpc −1)) 3 and ν = 2.04 +0.90 −0.89 .
Predicted and Observed Evolution in the Mean Properties of Type Ia Supernovae with Redshift
The Astrophysical Journal, 2007
Recent studies indicate that Type Ia supernovae (SNe Ia) consist of two groups-a "prompt" component whose rates are proportional to the host galaxy star formation rate, whose members have broader lightcurves and are intrinsically more luminous, and a "delayed" component whose members take several Gyr to explode, have narrower lightcurves, and are intrinsically fainter. As cosmic star formation density increases with redshift, the prompt component should begin to dominate. We use a two-component model to predict that the average lightcurve width should increase by 5% from z = 0 − 1.5. Using data from various searches we find a 9%±3% increase in average lightcurve width from z = 0.03 − 1.26, corresponding to an increase in the average intrinsic SN Ia luminosity of 14%. To test whether there is any residual bias after supernovae are corrected for lightcurve shape we use published data to mimic the effect of population evolution and find no significant difference in the measured dark energy equation of state parameter, w. However, future measurements of changes in w with time require standardization of SN Ia magnitudes to 2% up to z = 1.7, and it is not yet possible to assess whether lightcurve shape correction works at this level of precision. Another concern at z = 1.5 is the expected order of magnitude increase in the number of SNe Ia that cannot be calibrated by current methods.
Monthly Notices of the Royal Astronomical Society, 2013
Using a method to discover and classify supernovae (SNe) in galaxy spectra, we find 90 Type Ia SNe (SNe Ia) and 10 Type II SNe among the ∼700 000 galaxy spectra in the Sloan Digital Sky Survey Data Release 7 that have star-formation histories (SFHs) derived with the VErsatile SPectral Analysis code (VESPA). We use the SN Ia sample to measure SN Ia rates per unit stellar mass. We confirm, at the median redshift of the sample, z = 0.1, the inverse dependence on galaxy mass of the SN Ia rate per unit mass, previously reported by Li et al. for a local sample. We further confirm, following Kistler et al., that this relation can be explained by the combination of galaxy 'downsizing' and a power-law delay-time distribution (DTD; the distribution of times that elapse between a hypothetical burst of star formation and the subsequent SN Ia explosions) with an index of −1, inherent to the doubledegenerate progenitor scenario. We use the method of Maoz et al. to recover the DTD by comparing the number of SNe Ia hosted by each galaxy in our sample with the VESPA-derived SFH of the stellar population within the spectral aperture. In this galaxy sample, which is dominated by old and massive galaxies, we recover a 'delayed' component to the DTD of 4.5 ± 0.6 (statistical) +0.3 −0.5 (systematic) × 10 −14 SNe M −1 yr −1 for delays in the range >2.4 Gyr. The mass-normalized SN Ia rate, averaged over all masses and redshifts in our galaxy sample, is R Ia,M (z = 0.1) = 0.10 ± 0.01 (statistical) ± 0.01 (systematic) SNuM, and the volumetric rate is R Ia,V (z = 0.1) = 0.247 +0.029 −0.026 (statistical) +0.016 −0.031 (systematic) × 10 −4 SNe yr −1 Mpc −3. This rate is consistent with the rates and rate evolution from other recent SN Ia surveys, which together also indicate a ∼t −1 DTD.
The rates of type Ia supernovae - II. Diversity of events at low and high redshifts
Monthly Notices of the Royal Astronomical Society, 2010
This paper investigates the possible systematic difference of type Ia supernovae (SNe Ia) properties related to the age and masses of the progenitors that could introduce a systematic bias between low-and high-redshift SNe Ia. The relation between the main features of the distribution of delay times and the masses of the progenitors is illustrated for the single (SD) and double degenerate (DD) models. Mixed models, which assume contributions from both the SD and DD channels, are also presented and tested versus the observed correlations between the SN Ia rates and the parent galaxy properties. It is shown that these correlations can be accounted for with both single-channel and mixed models, and that the rate in S0 and E galaxies may effectively provide clues on the contribution of SD progenitors to late epoch explosions. A wide range of masses for the CO white dwarf at the start of accretion is expected in almost all galaxy types; only in galaxies of the earliest types are the properties of the progenitors expected to be more uniform. For mixed models, late-type galaxies should host SD and DD explosions in comparable fractions, while in early-type galaxies DD explosions should largely prevail. Events hosted by star-forming galaxies span a wide range of delay times; prompt events could dominate only in the presence of a strong starburst. It is concluded that nearby SN Ia samples should well include the young, massive and hot progenitors that necessarily dominate at high redshift.
The carnegie supernova project: analysis of the first sample of low-redshift type-Ia supernovae
The Astronomical …, 2010
An analysis of the first set of low-redshift (z<0.08) Type Ia supernovae monitored by the Carnegie Supernova Project between 2004 and 2006 is presented. The data consist of well-sampled, high-precision optical (ugriBV ) and near-infrared (NIR; Y JHK s ) light curves in a well-understood photometric system. Methods are described for deriving light-curve parameters, and for building template light curves which are used to fit Type Ia supernova data in the ugriBV Y JH bands. The intrinsic colors at maximum light are calibrated using a subsample of supernovae assumed to have suffered little or no reddening, enabling color excesses to be estimated for the full sample. The optical-NIR color excesses allow the properties of the reddening law in the host galaxies to be studied. A low average value of the total-to-selective absorption coefficient, R V ≈ 1.7, is derived when using the entire sample of supernovae. However, when the two highly reddened supernovae (SN 2005A and SN 2006X) in the sample are excluded, a value R V ≈ 3.2 is obtained, similar to the standard value for the Galaxy. The red colors of these two events are well matched by a model where multiple scattering of photons by circumstellar dust steepens the effective extinction law. The absolute peak magnitudes of the supernovae are studied in all bands using a two-parameter linear fit to the decline 1 This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.