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Sample records for ia supernova light

  1. Light Curve Models for Type IA Supernovae

    NASA Astrophysics Data System (ADS)

    Dominguez, Inmaculada

    1993-05-01

    The most widely accepted scenario for Type Ia supernovae is the thermonuclear explosion of a C+O white dwarf which, by accretion from a companion, approaches the Chandrasekhar mass. Whilst this scenario can account for most of the observed properties of SNe Ia, the exact nature of the explosion mechanism remains uncertain. This thesis presents the results obtained from hydrodynamical model calculations of post-explosion envelope expansion. The hydrodynamics are followed in spherical symmetry using a Lagrangean code, the energy equation being solved in the diffusion approximation. The conversion of decay gamma-rays into thermal energy is treated as an absorption process, while the time-dependent opacity is calculated as a function of composition, density, temperature and velocity gradient. The results of these models--light-curve shape, maximum luminosities, and expansion velocity profiles---are compared with the bolometric observational data (SN1981B, SN1972E and the composite light curve obtained by Leibundgut for 9 SNe Ia in Virgo) and current theoretical models of the explosion mechanism. Delayed detonation and deflagration models (Bravo 1990), adopting different C ignition densities, have been investigated. In all cases, the resulting light curve is in satisfactory agreement with observations. As the ignition density varies, the maximum of light remains nearly constant and the dispersion in the rates of decline of the light curve is compatible with observations. Moreover, variation in the ignition density readily accounts for the dispersion of 1000 km s^-1 in the observed expansion velocities. Delayed detonation models yield high kinetic energies, that result in (especially for the highest ignition densities) high expansion velocities, steep post-peak declines of the light curves and velocity distribution of intermediate-mass elements that are higher than that inferred from observations. Conversely, deflagration models provide less energetic explosions. However

  2. The rising light curves of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Firth, R. E.; Sullivan, M.; Gal-Yam, A.; Howell, D. A.; Maguire, K.; Nugent, P.; Piro, A. L.; Baltay, C.; Feindt, U.; Hadjiyksta, E.; McKinnon, R.; Ofek, E.; Rabinowitz, D.; Walker, E. S.

    2015-02-01

    We present an analysis of the early, rising light curves of 18 Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory and the La Silla-QUEST variability survey. We fit these early data flux using a simple power law (f(t) = α × tn) to determine the time of first light (t0), and hence the rise time (trise) from first light to peak luminosity, and the exponent of the power-law rise (n). We find a mean uncorrected rise time of 18.98 ± 0.54 d, with individual supernova (SN) rise times ranging from 15.98 to 24.7 d. The exponent n shows significant departures from the simple `fireball model' of n = 2 (or f(t) ∝ t2) usually assumed in the literature. With a mean value of n = 2.44 ± 0.13, our data also show significant diversity from event to event. This deviation has implications for the distribution of 56Ni throughout the SN ejecta, with a higher index suggesting a lesser degree of 56Ni mixing. The range of n found also confirms that the 56Ni distribution is not standard throughout the population of SNe Ia, in agreement with earlier work measuring such abundances through spectral modelling. We also show that the duration of the very early light curve, before the luminosity has reached half of its maximal value, does not correlate with the light-curve shape or stretch used to standardize SNe Ia in cosmological applications. This has implications for the cosmological fitting of SN Ia light curves.

  3. RADIOACTIVELY POWERED RISING LIGHT CURVES OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Piro, Anthony L.

    2012-11-10

    The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first Almost-Equal-To 0.5-4 days. In addition, studies of the composite light curves formed from stacking together many Type Ia supernovae (SNe Ia) have found similar power-law indices for the rise, but may also show some dispersion that may indicate diversity. I explore what range of power-law rises are possible due to the presence of radioactive material near the surface of the exploding white dwarf (WD). I summarize what constraints such a model places on the structure of the progenitor and the distribution and velocity of ejecta. My main conclusion is that for the inferred explosion time for SN 2011fe, its rise requires an increasing mass fraction X {sub 56} Almost-Equal-To (4-6) Multiplication-Sign 10{sup -2} of {sup 56}Ni distributed between a depth of Almost-Equal-To 10{sup -2} and 0.3 M {sub Sun} below the WD's surface. Radioactive elements this shallow are not found in simulations of a single C/O detonation. Scenarios that may produce this material include helium-shell burning during a double-detonation ignition, a gravitationally confined detonation, and a subset of deflagration to detonation transition models. In general, the power-law rise can differ from quadratic depending on the details of the velocity, density, and radioactive deposition gradients in a given event. Therefore, comparisons of this work with observed bolometric rises of SNe Ia would place strong constraints on the properties of the shallow outer layers, providing important clues for identifying the elusive progenitors of SNe Ia.

  4. Radioactively Powered Rising Light Curves of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Piro, Anthony L.

    2012-11-01

    The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first ≈0.5-4 days. In addition, studies of the composite light curves formed from stacking together many Type Ia supernovae (SNe Ia) have found similar power-law indices for the rise, but may also show some dispersion that may indicate diversity. I explore what range of power-law rises are possible due to the presence of radioactive material near the surface of the exploding white dwarf (WD). I summarize what constraints such a model places on the structure of the progenitor and the distribution and velocity of ejecta. My main conclusion is that for the inferred explosion time for SN 2011fe, its rise requires an increasing mass fraction X 56 ≈ (4-6) × 10-2 of 56Ni distributed between a depth of ≈10-2 and 0.3 M ⊙ below the WD's surface. Radioactive elements this shallow are not found in simulations of a single C/O detonation. Scenarios that may produce this material include helium-shell burning during a double-detonation ignition, a gravitationally confined detonation, and a subset of deflagration to detonation transition models. In general, the power-law rise can differ from quadratic depending on the details of the velocity, density, and radioactive deposition gradients in a given event. Therefore, comparisons of this work with observed bolometric rises of SNe Ia would place strong constraints on the properties of the shallow outer layers, providing important clues for identifying the elusive progenitors of SNe Ia.

  5. Theoretical light curves for deflagration models of type Ia supernova

    NASA Astrophysics Data System (ADS)

    Blinnikov, S. I.; Röpke, F. K.; Sorokina, E. I.; Gieseler, M.; Reinecke, M.; Travaglio, C.; Hillebrandt, W.; Stritzinger, M.

    2006-07-01

    Aims.We present synthetic bolometric and broad-band UBVRI light curves of SNe Ia for four selected 3D deflagration models of thermonuclear supernovae. Methods: .The light curves are computed with the 1D hydro code stella, which models (multi-group time-dependent) non-equilibrium radiative transfer inside SN ejecta. Angle-averaged results from 3D hydrodynamical explosion simulations with the composition determined in a nucleosynthetic postprocessing step served as the input to the radiative transfer model. Results: .The predicted model {UBV} light curves do agree reasonably well with the observed ones for SNe Ia in the range of low to normal luminosities, although the underlying hydrodynamical explosion models produced only a modest amount of radioactive {}56Ni(i.e. 0.24-0.42 M⊙) and relatively low kinetic energy in the explosion (less than 0.7 × 1051 erg). The evolution of predicted B and V fluxes in the model with a {}56Nimass of 0.42 M⊙ follows the observed decline rate after the maximum very well, although the behavior of fluxes in other filters deviates somewhat from observations, and the bolometric decline rate is a bit slow. The material velocity at the photospheric level is on the order of 104 km s-1 for all models. Using our models, we check the validity of Arnett's rule, relating the peak luminosity to the power of the deposited radioactive heating, and we also check the accuracy of the procedure for extracting the {}56Nimass from the observed light curves. Conclusions: .We find that the comparison between theoretical light curves and observations provides a useful tool to validate SN Ia models. The steps necessary for improving the agreement between theory and observations are set out.

  6. The effect of background galaxy contamination on the absolute magnitude and light curve speed class of type Ia supernovae

    NASA Technical Reports Server (NTRS)

    Boisseau, John R.; Wheeler, J. Craig

    1991-01-01

    Observational data are presented in support of the hypothesis that background galaxy contamination is present in the photometric data of Ia supernovae and that this effect can account for the observed dispersion in the light curve speeds of most of Ia supernovae. The implication is that the observed dispersion in beta is artificial and that most of Ia supernovae have nearly homogeneous light curves. The result supports the notion that Ia supernovae are good standard candles.

  7. Late Light Curves of SN 2002cx-like Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Lair, Jessica C.; Kilgore, E. E.; Milne, P.; Bryngelson, G. L.; Leising, M. D.

    2013-01-01

    The use of Type Ia Supernovae (SNe Ia) in cosmological studies as “standard candle” distance indicators lead to the need for a better understanding of these objects. SN 2002cx was a very peculiar SNe Ia that did not fit into any of the known subclasses of SNe Ia and needs to be further understood. We present late-time optical photometry of three more recently discovered objects that have been determined to be SN 2002cx-like Type Ia supernovae: SN 2005hk, SN 2008A, and SN 2008ae. The light curves of these objects show late-time decline rates that are slower than what is seen in normal SNe Ia in the V,R, and I bands, but faster in the B-band.

  8. Preliminary NIR Late Light Curve of the Type Ia Supernova SN2009nr

    NASA Astrophysics Data System (ADS)

    Heath, Jonathan; Bryngelson, G.

    2013-01-01

    Type Ia supernovae (SNe Ia) are important in determining the expansion of the universe based on the uniformity of their light curves. It is essential to understand the behavior of these supernovae in order to strengthen our confidence in their use as standard candles. A small, but increasing number of SNe Ia have been observed later than the 200 day epoch in the near-infrared (NIR). Most of these exhibit a flattening of the NIR power, even as the visible light declines at a steady rate. It is unclear as to exactly what causes this behavior, and how typical it is. In order to characterize the late behavior of SNe Ia, images of the supernova SN2009nr were analyzed using the Image Reduction and Analysis Facility (IRAF). These images were taken with the 4m Mayall Telescope at Kitt Peak National-Observatory using the FLAMINGOS IR Imaging Spectrometer. The supernova’s magnitude was normalized with respect to the magnitudes of known stars so that traits related to the supernova may be compared to others. We present preliminary NIR (J, H, K) light curves of the observed supernova and compare them to other SNe Ia observed at these epochs.

  9. Type Ia supernovae: Pulsating delayed detonation models, IR light curves, and the formation of molecules

    NASA Technical Reports Server (NTRS)

    Hoflich, Peter; Khokhlov, A.; Wheeler, C.

    1995-01-01

    We computed optical and infrared light curves of the pulsating class of delayed detonation models for Type Ia supernovae (SNe Ia). It is demonstrated that observations of the IR light curves can be used to identify subluminous SNe Ia by testing whether secondary maxima occur in the IR. Our pulsating delayed detonation models are in agreement with current observations both for subluminous and normal bright SN Ia, namely SN1991bg, SN1992bo, and SN1992bc. Observations of molecular bands provide a test to distinguish whether strongly subluminous supernovae are a consequence of the pulsating mechanism occurring in a high-mass white dwarf (WD) or, alternatively, are formed by the helium detonation in a low-mass WD as was suggested by Woosley. In the latter case, no carbon is left after the explosion of low-mass WDs whereas a log of C/O-rich material is present in pulsating delayed detonation models.

  10. SALT spectroscopic classification of PS15bzz as a type-Ia supernova at maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Smith, K. W.; Wright, D.; Smartt, S. J.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Miszalski, B.

    2015-09-01

    We obtained SALT (+RSS) spectroscopy of PS15bzz on 2015 Aug 16.9 UT, covering the wavelength range 360-820 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows PS15bzz is a type-Ia supernova within a few days of maximum light.

  11. Light Echoes and Late-Time Emissions of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Drozdov, Dina

    2016-05-01

    Type Ia supernovae have many applications in astronomy, yet with fundamental properties still not fully understood, new methods for investigating the environment of a supernova need to be developed. A light echo is produced from the scattering of light from a bright source and can be used to analyze the dust in the vicinity of the supernova and learn invaluable information about the source. These techniques can put constraints on explosion and progenitor models. Although light echo detections from Type Ia supernovae are rare, with only seven total extragalactic detections, this could be due to the lack of thorough late-epoch monitoring. Since key information is determined from even a single light echo detection, light echo searches should be undertaken in the future to supplement our understanding of supernovae. As part of our collaborative campaign for studying the emission of supernovae at late epochs, we have added two light echoes to a small sample size of Type Ia supernova light echo detections: SN 2009ig in NGC 1015 and a dual echo from SN 2007af in NGC 5584. Both echoes were observed with the Hubble Space Telescope and allow for the most detailed images of Type Ia supernova light echoes to date. Three filters (F555W, F814W, and F350LP) captured the echoes obtained with the Wide Field Camera 3, and since both host galaxies were imaged as part of the same observing program, these cases will be the best comparable light echo pairs. We also further investigate the light echoes from SN 2006X in NGC 4321 and SN 1998bu in NGC 3368 from Hubble Space Telescope archival images. Analyses performed on the images gives crucial insight into the dusty environment of the host galaxy and the surroundings of the supernova. The outer echo from SN 2007af was created from an interstellar dust sheet located ~800 pc in front of the supernova, while the inner echo could be from interstellar or circumstellar origin. A circumstellar light echo could imply a single degenerate

  12. CfA3: 185 TYPE Ia SUPERNOVA LIGHT CURVES FROM THE CfA

    SciTech Connect

    Hicken, Malcolm; Challis, Peter; Kirshner, Robert P.; Bakos, Gaspar; Berlind, Perry; Brown, Warren R.; Caldwell, Nelson; Calkins, Mike; Cho, Richard; Contreras, Maria; Jha, Saurabh; Matheson, Tom; Modjaz, Maryam; Rest, Armin; Michael Wood-Vasey, W.; Barton, Elizabeth J.; Bragg, Ann; Briceno, Cesar; Ciupik, Larry; Dendy, Kristi-Concannon E-mail: kirshner@cfa.harvard.edu

    2009-07-20

    We present multiband photometry of 185 type-Ia supernovae (SNe Ia), with over 11,500 observations. These were acquired between 2001 and 2008 at the F. L. Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics (CfA). This sample contains the largest number of homogeneously observed and reduced nearby SNe Ia (z {approx}< 0.08) published to date. It more than doubles the nearby sample, bringing SN Ia cosmology to the point where systematic uncertainties dominate. Our natural system photometry has a precision of {approx}<0.02 mag in BVRIr'i' and {approx}<0.04 mag in U for points brighter than 17.5 mag. We also estimate a systematic uncertainty of 0.03 mag in our SN Ia standard system BVRIr'i' photometry and 0.07 mag for U. Comparisons of our standard system photometry with published SN Ia light curves and comparison stars, where available for the same SN, reveal agreement at the level of a few hundredths mag in most cases. We find that 1991bg-like SNe Ia are sufficiently distinct from other SNe Ia in their color and light-curve-shape/luminosity relation that they should be treated separately in light-curve/distance fitter training samples. The CfA3 sample will contribute to the development of better light-curve/distance fitters, particularly in the few dozen cases where near-infrared photometry has been obtained and, together, can help disentangle host-galaxy reddening from intrinsic supernova color, reducing the systematic uncertainty in SN Ia distances due to dust.

  13. TYPE Ia SUPERNOVA LIGHT-CURVE INFERENCE: HIERARCHICAL BAYESIAN ANALYSIS IN THE NEAR-INFRARED

    SciTech Connect

    Mandel, Kaisey S.; Friedman, Andrew S.; Kirshner, Robert P.; Wood-Vasey, W. Michael

    2009-10-10

    We present a comprehensive statistical analysis of the properties of Type Ia supernova (SN Ia) light curves in the near-infrared using recent data from Peters Automated InfraRed Imaging TELescope and the literature. We construct a hierarchical Bayesian framework, incorporating several uncertainties including photometric error, peculiar velocities, dust extinction, and intrinsic variations, for principled and coherent statistical inference. SN Ia light-curve inferences are drawn from the global posterior probability of parameters describing both individual supernovae and the population conditioned on the entire SN Ia NIR data set. The logical structure of the hierarchical model is represented by a directed acyclic graph. Fully Bayesian analysis of the model and data is enabled by an efficient Markov Chain Monte Carlo algorithm exploiting the conditional probabilistic structure using Gibbs sampling. We apply this framework to the JHK{sub s} SN Ia light-curve data. A new light-curve model captures the observed J-band light-curve shape variations. The marginal intrinsic variances in peak absolute magnitudes are sigma(M{sub J}) = 0.17 +- 0.03, sigma(M{sub H}) = 0.11 +- 0.03, and sigma(M{sub Ks}) = 0.19 +- 0.04. We describe the first quantitative evidence for correlations between the NIR absolute magnitudes and J-band light-curve shapes, and demonstrate their utility for distance estimation. The average residual in the Hubble diagram for the training set SNe at cz > 2000kms{sup -1} is 0.10 mag. The new application of bootstrap cross-validation to SN Ia light-curve inference tests the sensitivity of the statistical model fit to the finite sample and estimates the prediction error at 0.15 mag. These results demonstrate that SN Ia NIR light curves are as effective as corrected optical light curves, and, because they are less vulnerable to dust absorption, they have great potential as precise and accurate cosmological distance indicators.

  14. Standardization of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Coelho, Rodrigo C. V.; Calvão, Maurício O.; Reis, Ribamar R. R.; Siffert, Beatriz B.

    2015-01-01

    Type Ia supernovae (SNe Ia) have been intensively investigated due to their great homogeneity and high luminosity, which make it possible to use them as standardizable candles for the determination of cosmological parameters. In 2011, the physics Nobel prize was awarded ‘for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.’ This is a pedagogical article, aimed at those starting their study of that subject, in which we dwell on some topics related to the analysis of SNe Ia and their use in luminosity distance estimators. Here, we investigate their spectral properties and light curve standardization, paying careful attention to the fundamental quantities directly related to the SNe Ia observables. Finally, we describe our own step-by-step implementation of a classical light curve fitter, the stretch, applying it to real data from the Carnegie Supernova Project.

  15. Improved Distances to Type Ia Supernovae withMulticolor Light Curve Shapes: MLCS2k2

    SciTech Connect

    Jha, Saurabh; Riess, Adam G.; Kirshner, Robert P.; /Harvard-Smithsonian Ctr. Astrophys.

    2007-01-05

    We present an updated version of the Multicolor Light Curve Shape method to measure distances to type Ia supernovae (SN Ia), incorporating new procedures for K-correction and extinction corrections. We also develop a simple model to disentangle intrinsic color variations and reddening by dust, and expand the method to incorporate U-band light curves and to more easily accommodate prior constraints on any of the model parameters. We apply this method to 133 nearby SN Ia, including 95 objects in the Hubble flow (cz {ge} 2500 km s{sup -1}), which give an intrinsic dispersion of less than 7% in distance. The Hubble flow sample, which is of critical importance to all cosmological uses of SN Ia, is the largest ever presented with homogeneous distances. We find the Hubble flow supernovae with H{sub 0}d{sub SN} {ge} 7400 km s{sup -1} yield an expansion rate that is 6.5 {+-} 1.8% lower than the rate determined from supernovae within that distance, and this can have a large effect on measurements of the dark energy equation of state with SN Ia. Peculiar velocities of SN Ia host galaxies in the rest frame of the Local Group are consistent with the dipole measured in the Cosmic Microwave Background. Direct fits of SN Ia that are significantly reddened by dust in their host galaxies suggest their mean extinction law may be described by R{sub V} {approx_equal} 2.7, but optical colors alone provide weak constraints on R{sub V}.

  16. CfAIR2: Near-infrared Light Curves of 94 Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Friedman, Andrew S.; Wood-Vasey, W. M.; Marion, G. H.; Challis, Peter; Mandel, Kaisey S.; Bloom, Joshua S.; Modjaz, Maryam; Narayan, Gautham; Hicken, Malcolm; Foley, Ryan J.; Klein, Christopher R.; Starr, Dan L.; Morgan, Adam; Rest, Armin; Blake, Cullen H.; Miller, Adam A.; Falco, Emilio E.; Wyatt, William F.; Mink, Jessica; Skrutskie, Michael F.; Kirshner, Robert P.

    2015-09-01

    CfAIR2 is a large, homogeneously reduced set of near-infrared (NIR) light curves (LCs) for Type Ia supernovae (SNe Ia) obtained with the 1.3 m Peters Automated InfraRed Imaging TELescope. This data set includes 4637 measurements of 94 SNe Ia and 4 additional SNe Iax observed from 2005 to 2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes {{JHK}}s photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z ˜ 0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More than half of the LCs begin before the time of maximum, and the coverage typically contains ˜13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for SN cosmology studies in the NIR. Because SN Ia are more nearly standard candles in the NIR and are less vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the SN cosmology community develop more precise and accurate extragalactic distance probes to improve our knowledge of cosmological parameters, including dark energy and its potential time variation.

  17. Near-infrared light curves of Type Ia supernovae: studying properties of the second maximum

    NASA Astrophysics Data System (ADS)

    Dhawan, S.; Leibundgut, B.; Spyromilio, J.; Maguire, K.

    2015-04-01

    Type Ia supernovae (SNe Ia) have been proposed to be much better distance indicators at near-infrared (NIR) compared to optical wavelengths - the effect of dust extinction is expected to be lower and it has been shown that SNe Ia behave more like `standard candles' at NIR wavelengths. To better understand the physical processes behind this increased uniformity, we have studied the Y, J and H-filter light curves of 91 SNe Ia from the literature. We show that the phases and luminosities of the first maximum in the NIR light curves are extremely uniform for our sample. The phase of the second maximum, the late-phase NIR luminosity and the optical light-curve shape are found to be strongly correlated, in particular more luminous SNe Ia reach the second maximum in the NIR filters at a later phase compared to fainter objects. We also find a strong correlation between the phase of the second maximum and the epoch at which the SN enters the Lira law phase in its optical colour curve (epochs ˜ 15 to 30 d after B-band maximum). The decline rate after the second maximum is very uniform in all NIR filters. We suggest that these observational parameters are linked to the nickel and iron mass in the explosion, providing evidence that the amount of nickel synthesized in the explosion is the dominating factor shaping the optical and NIR appearance of SNe Ia.

  18. Cosmological parameter uncertainties from SALT-II type Ia supernova light curve models

    SciTech Connect

    Mosher, J.; Sako, M.; Guy, J.; Astier, P.; Betoule, M.; El-Hage, P.; Pain, R.; Regnault, N.; Marriner, J.; Biswas, R.; Kuhlmann, S.; Schneider, D. P.

    2014-09-20

    We use simulated type Ia supernova (SN Ia) samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and a bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: ∼120 low-redshift (z < 0.1) SNe Ia, ∼255 Sloan Digital Sky Survey SNe Ia (z < 0.4), and ∼290 SNLS SNe Ia (z ≤ 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (w {sub input} – w {sub recovered}) ranging from –0.005 ± 0.012 to –0.024 ± 0.010. These biases are indistinguishable from each other within the uncertainty; the average bias on w is –0.014 ± 0.007.

  19. Cosmological Parameter Uncertainties from SALT-II Type Ia Supernova Light Curve Models

    SciTech Connect

    Mosher, J.; Guy, J.; Kessler, R.; Astier, P.; Marriner, J.; Betoule, M.; Sako, M.; El-Hage, P.; Biswas, R.; Pain, R.; Kuhlmann, S.; Regnault, N.; Frieman, J. A.; Schneider, D. P.

    2014-08-29

    We use simulated type Ia supernova (SN Ia) samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and a bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: ~120 low-redshift (z < 0.1) SNe Ia, ~255 Sloan Digital Sky Survey SNe Ia (z < 0.4), and ~290 SNLS SNe Ia (z ≤ 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (w (input) – w (recovered)) ranging from –0.005 ± 0.012 to –0.024 ± 0.010. These biases are indistinguishable from each other within the uncertainty, the average bias on w is –0.014 ± 0.007.

  20. Comparing the Light Curves of Simulated Type Ia Supernovae with Observations Using Data-driven Models

    NASA Astrophysics Data System (ADS)

    Diemer, Benedikt; Kessler, Richard; Graziani, Carlo; Jordan, George C., IV; Lamb, Donald Q.; Long, Min; van Rossum, Daniel R.

    2013-08-01

    We propose a robust, quantitative method to compare the synthetic light curves of a Type Ia supernova (SN Ia) explosion model with a large set of observed SNe Ia, and derive a figure of merit for the explosion model's agreement with observations. The synthetic light curves are fit with the data-driven model SALT2 which returns values for stretch, color, and magnitude at peak brightness, as well as a goodness-of-fit parameter. Each fit is performed multiple times with different choices of filter bands and epoch range in order to quantify the systematic uncertainty on the fitted parameters. We use a parametric population model for the distribution of observed SN Ia parameters from large surveys, and extend it to represent red, dim, and bright outliers found in a low-redshift SN Ia data set. We discuss the potential uncertainties of this population model and find it to be reliable given the current uncertainties on cosmological parameters. Using our population model, we assign each set of fitted parameters a likelihood of being observed in nature, and a figure of merit based on this likelihood. We define a second figure of merit based on the quality of the light curve fit, and combine the two measures into an overall figure of merit for each explosion model. We compute figures of merit for a variety of one-, two-, and three-dimensional explosion models and show that our evaluation method allows meaningful inferences across a wide range of light curve quality and fitted parameters.

  1. TYPE Ia SUPERNOVA LIGHT CURVE INFERENCE: HIERARCHICAL MODELS IN THE OPTICAL AND NEAR-INFRARED

    SciTech Connect

    Mandel, Kaisey S.; Narayan, Gautham; Kirshner, Robert P.

    2011-04-20

    We have constructed a comprehensive statistical model for Type Ia supernova (SN Ia) light curves spanning optical through near-infrared (NIR) data. A hierarchical framework coherently models multiple random and uncertain effects, including intrinsic supernova (SN) light curve covariances, dust extinction and reddening, and distances. An improved BAYESN Markov Chain Monte Carlo code computes probabilistic inferences for the hierarchical model by sampling the global probability density of parameters describing individual SNe and the population. We have applied this hierarchical model to optical and NIR data of 127 SNe Ia from PAIRITEL, CfA3, Carnegie Supernova Project, and the literature. We find an apparent population correlation between the host galaxy extinction A{sub V} and the ratio of total-to-selective dust absorption R{sub V} . For SNe with low dust extinction, A{sub V} {approx}< 0.4, we find R{sub V} {approx} 2.5-2.9, while at high extinctions, A{sub V} {approx}> 1, low values of R{sub V} < 2 are favored. The NIR luminosities are excellent standard candles and are less sensitive to dust extinction. They exhibit low correlation with optical peak luminosities, and thus provide independent information on distances. The combination of NIR and optical data constrains the dust extinction and improves the predictive precision of individual SN Ia distances by about 60%. Using cross-validation, we estimate an rms distance modulus prediction error of 0.11 mag for SNe with optical and NIR data versus 0.15 mag for SNe with optical data alone. Continued study of SNe Ia in the NIR is important for improving their utility as precise and accurate cosmological distance indicators.

  2. The Rise and Fall of Type Ia Supernova Light Curves in the SDSS-II Supernova Survey

    SciTech Connect

    Hayden, Brian T.; Garnavich, Peter M.; Kessler, Richard; Frieman, Joshua A.; Jha, Saurabh W.; Bassett, Bruce; Cinabro, David; Dilday, Benjamin; Kasen, Daniel; Marriner, John; Nichol, Robert C.; /Portsmouth U., ICG /Baltimore, Space Telescope Sci. /Johns Hopkins U.

    2010-01-01

    We analyze the rise and fall times of Type Ia supernova (SN Ia) light curves discovered by the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. From a set of 391 light curves k-corrected to the rest-frame B and V bands, we find a smaller dispersion in the rising portion of the light curve compared to the decline. This is in qualitative agreement with computer models which predict that variations in radioactive nickel yield have less impact on the rise than on the spread of the decline rates. The differences we find in the rise and fall properties suggest that a single 'stretch' correction to the light curve phase does not properly model the range of SN Ia light curve shapes. We select a subset of 105 light curves well observed in both rise and fall portions of the light curves and develop a '2-stretch' fit algorithm which estimates the rise and fall times independently. We find the average time from explosion to B-band peak brightness is 17.38 {+-} 0.17 days, but with a spread of rise times which range from 13 days to 23 days. Our average rise time is shorter than the 19.5 days found in previous studies; this reflects both the different light curve template used and the application of the 2-stretch algorithm. The SDSS-II supernova set and the local SNe Ia with well-observed early light curves show no significant differences in their average rise-time properties. We find that slow-declining events tend to have fast rise times, but that the distribution of rise minus fall time is broad and single peaked. This distribution is in contrast to the bimodality in this parameter that was first suggested by Strovink (2007) from an analysis of a small set of local SNe Ia. We divide the SDSS-II sample in half based on the rise minus fall value, t{sub r} - t{sub f} {approx}< 2 days and t{sub r} - t{sub f} > 2 days, to search for differences in their host galaxy properties and Hubble residuals; we find no difference in host galaxy properties or Hubble residuals in our

  3. Dust around Type Ia supernovae

    SciTech Connect

    Wang, Lifan

    2005-10-20

    An explanation is given of the low value of R lambda triple bond A lambda/E(B - V), the ratio of absolute to selective extinction deduced from Type Ia supernova observations. The idea involves scattering by dust clouds located in the circumstellar environment, or at the highest velocity shells of the supernova ejecta. The scattered light tends to reduce the effective R lambda in the optical, but has an opposite effect in the ultraviolet. The presence of circumstellar dust can be tested by ultraviolet to near infrared observations and by multi-epoch spectropolarimetry of SNe Ia.

  4. Tycho Brahe's 1572 supernova as a standard type Ia as revealed by its light-echo spectrum.

    PubMed

    Krause, Oliver; Tanaka, Masaomi; Usuda, Tomonori; Hattori, Takashi; Goto, Miwa; Birkmann, Stephan; Nomoto, Ken'ichi

    2008-12-01

    Type Ia supernovae are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions about supernovae are how the explosion actually proceeds and whether accretion occurs from a companion or by the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN 1572) is thought to be one of the best candidates for a type Ia supernova in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the hitherto unknown spectroscopic type of this supernova is crucial in relating these results to the diverse population of type Ia supernovae. Here we report an optical spectrum of Tycho's supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light from the explosion swept past the Earth. We find that SN 1572 belongs to the majority class of normal type Ia supernovae. PMID:19052622

  5. Tycho Brahe's 1572 supernova as a standard typeIa as revealed by its light-echo spectrum

    NASA Astrophysics Data System (ADS)

    Krause, Oliver; Tanaka, Masaomi; Usuda, Tomonori; Hattori, Takashi; Goto, Miwa; Birkmann, Stephan; Nomoto, Ken'ichi

    2008-12-01

    TypeIa supernovae are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions about supernovae are how the explosion actually proceeds and whether accretion occurs from a companion or by the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN1572) is thought to be one of the best candidates for a typeIa supernova in the Milky Way. The proximity of the SN1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the hitherto unknown spectroscopic type of this supernova is crucial in relating these results to the diverse population of typeIa supernovae. Here we report an optical spectrum of Tycho's supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light from the explosion swept past the Earth. We find that SN1572 belongs to the majority class of normal typeIa supernovae.

  6. Multidimensional radiative transfer calculations of the light curves and spectra of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Kasen, D.; Thomas, R. C.; Röpke, F.; Woosley, S. E.

    2008-07-01

    The explosion of a white dwarf star in a Type Ia supernova (SN Ia) explosion leads to the burning and ejection of stellar material at a few percent of the speed of light. The spectacle we observe in the months that follow is from the leaking of radiation from this glowing mass of radioactive debris. The modeling of SN Ia light curves and spectra represents a complex problem in time-dependent radiative transfer. Here we discuss numerical methods, in particular Monte Carlo methods, for calculating 3D multi-wavelength radiative transport on massively parallel machines. Our approach involves a newly developed domain decomposition technique in which the memory load is distributed over multiple processors and photon packets are communicated from node to node. We present results for 2-dimensional models that explore white dwarf explosions over a range of explosion paradigms and ignition conditions. These models give insight into how variations in the initial conditions of the explosion affect the light curve we finally observe. We conclude with an outlook (and some initial results) for large scale 3D radiation transport calculations of SNe Ia in an era of petascale computing.

  7. PSN J01440799-6107074 is a type-Ia supernova near maximum light

    NASA Astrophysics Data System (ADS)

    Cao, Y.; Kasliwal, M.; Parker, S.; Hsiao, E. Y.; Gonzalez, C.; Phillips, M. M.; Morrell, N.; Contreras, C.

    2014-03-01

    We report on the spectroscopic classification of PSN J01440799-6107074 using a near-infrared spectrogram (range 800-2500 nm) obtained on Mar. 8.02 UT with the FoldedPort Infrared Echellette (FIRE) spectrograph on the 6.5-m Magellan Baade Telescope at Las Campanas Observatory. The near-infrared spectrum shows that it is a type-Ia supernova. The spectrum resembles the near-infrared spectrum of SN 2011fe at maximum light (Hsiao et al.

  8. Type IA Supernovae

    NASA Technical Reports Server (NTRS)

    Wheeler, J. Craig

    1992-01-01

    Spectral calculations show that a model based on the thermonuclear explosion of a degenerate carbon/oxygen white dwarf provides excellent agreement with observations of Type Ia supernovae. Identification of suitable evolutionary progenitors remains a severe problem. General problems with estimation of supernova rates are outlined and the origin of Type Ia supernovae from double degenerate systems are discussed in the context of new rates of explosion per H band luminosity, the lack of observed candidates, and the likely presence of H in the vicinity of some SN Ia events. Re-examination of the problems of triggering Type Ia by accretion of hydrogen from a companion shows that there may be an avenue involving cataclysmic variables, especially if extreme hibernation occurs. Novae may channel accreting white dwarfs to a unique locus in accretion rate/mass space. Systems that undergo secular evolution to higher mass transfer rates could lead to just the conditions necessary for a Type Ia explosion. Tests involving fluorescence or absorption in a surrounding circumstellar medium and the detection of hydrogen stripped from a companion, which should appear at low velocity inside the white dwarf ejecta, are suggested. Possible observational confirmation of the former is described.

  9. Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light Curves

    SciTech Connect

    Hicken, Malcolm; Wood-Vasey, W.Michael; Blondin, Stephane; Challis, Peter; Jha, Saurabh; Kelly, Patrick L.; Rest, Armin; Kirshner, Robert P.; /Harvard-Smithsonian Ctr. Astrophys.

    2012-04-06

    We combine the CfA3 supernovae Type Ia (SN Ia) sample with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al. to form the Constitution set and, combined with a BAO prior, produces 1 + w = 0.013{sub -0.068}{sup +0.066} (0.11 syst), consistent with the cosmological constant. The CfA3 addition makes the cosmologically useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role. We use four light-curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R{sub V} = 3.1), and MLCS2k2 (R{sub V} = 1.7). SALT produces high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 < {Delta} < 1.2. MLCS2k2 with R{sub V} = 3.1 overestimates host-galaxy extinction while R{sub V} {approx} 1.7 does not. Our investigation is consistent with no Hubble bubble. We also find that, after light-curve correction, SN Ia in Scd/Sd/Irr hosts are intrinsically fainter than those in E/S0 hosts by 2{sigma}, suggesting that they may come from different populations. We also find that SN Ia in Scd/Sd/Irr hosts have low scatter (0.1 mag) and reddening. Current systematic errors can be reduced by improving SN Ia photometric accuracy, by including the CfA3 sample to retrain light-curve fitters, by combining optical SN Ia photometry with near-infrared photometry to understand host-galaxy extinction, and by determining if different environments give rise to different intrinsic SN Ia luminosity after correction for light-curve shape and color.

  10. IMPROVED DARK ENERGY CONSTRAINTS FROM {approx}100 NEW CfA SUPERNOVA TYPE Ia LIGHT CURVES

    SciTech Connect

    Hicken, Malcolm; Challis, Peter; Kirshner, Robert P.; Wood-Vasey, W. Michael; Blondin, Stephane; Jha, Saurabh; Kelly, Patrick L.; Rest, Armin E-mail: kirshner@cfa.harvard.edu

    2009-08-01

    We combine the CfA3 supernovae Type Ia (SN Ia) sample with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al. to form the Constitution set and, combined with a BAO prior, produces 1 + w = 0.013{sup +0.066} {sub -0.068} (0.11 syst), consistent with the cosmological constant. The CfA3 addition makes the cosmologically useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role. We use four light-curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R{sub V} = 3.1), and MLCS2k2 (R{sub V} = 1.7). SALT produces high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 < {delta} < 1.2. MLCS2k2 with R{sub V} = 3.1 overestimates host-galaxy extinction while R{sub V} {approx} 1.7 does not. Our investigation is consistent with no Hubble bubble. We also find that, after light-curve correction, SN Ia in Scd/Sd/Irr hosts are intrinsically fainter than those in E/S0 hosts by 2{sigma}, suggesting that they may come from different populations. We also find that SN Ia in Scd/Sd/Irr hosts have low scatter (0.1 mag) and reddening. Current systematic errors can be reduced by improving SN Ia photometric accuracy, by including the CfA3 sample to retrain light-curve fitters, by combining optical SN Ia photometry with near-infrared photometry to understand host-galaxy extinction, and by determining if different environments give rise to different intrinsic SN Ia luminosity after correction for light-curve shape and color.

  11. CfA4: LIGHT CURVES FOR 94 TYPE Ia SUPERNOVAE

    SciTech Connect

    Hicken, Malcolm; Challis, Peter; Kirshner, Robert P.; Bakos, Gaspar; Berlind, Perry; Brown, Warren R.; Caldwell, Nelson; Calkins, Mike; Falco, Emilio; Fernandez, Jose; Friedman, Andrew S.; Groner, Ted; Hartman, Joel; Rest, Armin; Cramer, Claire E.; Wood-Vasey, W. Michael; Currie, Thayne; De Kleer, Kathy; Esquerdo, Gil; Everett, Mark; and others

    2012-06-01

    We present multi-band optical photometry of 94 spectroscopically confirmed Type Ia supernovae (SNe Ia) in the redshift range 0.0055-0.073, obtained between 2006 and 2011. There are a total of 5522 light-curve points. We show that our natural-system SN photometry has a precision of {approx}< 0.03 mag in BVr'i', {approx}< 0.06 mag in u', and {approx}< 0.07 mag in U for points brighter than 17.5 mag and estimate that it has a systematic uncertainty of 0.014, 0.010, 0.012, 0.014, 0.046, and 0.073 mag in BVr'i'u'U, respectively. Comparisons of our standard-system photometry with published SN Ia light curves and comparison stars reveal mean agreement across samples in the range of {approx}0.00-0.03 mag. We discuss the recent measurements of our telescope-plus-detector throughput by direct monochromatic illumination by Cramer et al. This technique measures the whole optical path through the telescope, auxiliary optics, filters, and detector under the same conditions used to make SN measurements. Extremely well characterized natural-system passbands (both in wavelength and over time) are crucial for the next generation of SN Ia photometry to reach the 0.01 mag accuracy level. The current sample of low-z SNe Ia is now sufficiently large to remove most of the statistical sampling error from the dark-energy error budget. But pursuing the dark-energy systematic errors by determining highly accurate detector passbands, combining optical and near-infrared (NIR) photometry and spectra, using the nearby sample to illuminate the population properties of SNe Ia, and measuring the local departures from the Hubble flow will benefit from larger, carefully measured nearby samples.

  12. SUPER-CHANDRASEKHAR-MASS LIGHT CURVE MODELS FOR THE HIGHLY LUMINOUS TYPE Ia SUPERNOVA 2009dc

    SciTech Connect

    Kamiya, Yasuomi; Tanaka, Masaomi; Nomoto, Ken'ichi; Blinnikov, Sergei I.; Sorokina, Elena I.; Suzuki, Tomoharu

    2012-09-10

    Several highly luminous Type Ia supernovae (SNe Ia) have been discovered. Their high luminosities are difficult to explain with the thermonuclear explosions of Chandrasekhar-mass white dwarfs (WDs). In the present study, we estimate the progenitor mass of SN 2009dc, one of the extremely luminous SNe Ia, using the hydrodynamical models as follows. Explosion models of super-Chandrasekhar-mass (super-Ch-mass) WDs are constructed, and multi-color light curves (LCs) are calculated. The comparison between our calculations and the observations of SN 2009dc suggests that the exploding WD has a super-Ch mass of 2.2-2.4 M{sub Sun }, producing 1.2-1.4 M{sub Sun} of {sup 56}Ni, if the extinction by its host galaxy is negligible. If the extinction is significant, the exploding WD is as massive as {approx}2.8 M{sub Sun }, and {approx}1.8 M{sub Sun} of {sup 56}Ni is necessary to account for the observations. Whether the host-galaxy extinction is significant or not, the progenitor WD must have a thick carbon-oxygen layer in the outermost zone (20%-30% of the WD mass), which explains the observed low expansion velocity of the ejecta and the presence of carbon. Our estimate of the mass of the progenitor WD, especially for the extinction-corrected case, is challenging to the current scenarios of SNe Ia. Implications for the progenitor scenarios are also discussed.

  13. VizieR Online Data Catalog: Light curves of type Ia supernovae in SNLS (Guy+, 2010)

    NASA Astrophysics Data System (ADS)

    Guy, J.; Sullivan, M.; Conley, A.; Regnault, N.; Astier, P.; Balland, C.; Basa, S.; Carlberg, R. G.; Fouchez, D.; Hardin, D.; Hook, I. M.; Howell, D. A.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K. M.; Pritchet, C. J.; Rich, J.; Ruhlmann-Kleider, V.; Balam, D.; Baumont, S.; Ellis, R. S.; Fabbro, S.; Fakhouri, H. K.; Fourmanoit, N.; Gonzalez-Gaitan, S.; Graham, M. L.; Hsiao, E.; Kronborg, T.; Lidman, C.; Mourao, A. M.; Perlmutter, S.; Ripoche, P.; Suzuki, N.; Walker, E. S.

    2010-07-01

    The following files contain the Type Ia supernovae light curves of the Supernova Legacy Survey 3-year sample and the parameters needed to estimate luminosity distances: the apparent rest-frame B-band magnitude at maximum light, a shape parameter (stretch factor or X1) and a colour that approximately corresponds to the rest-frame B-V colour (plus a constant offset) at maximum light in B-band. Those parameters were obtained with two light curve fitters: SALT2 (Guy et al., 2007A&A...466...11G) and SiFTO (Conley et al., 2008ApJ...681..482C). The light curves are in the magnitude system defined in Regnault et al. (2009, Cat. J/A+A/506/999). Fluxes and uncertainties are given for a fiducial zero point of 30, a magnitude is mag=-2.5log10(Flux)+30. An additional table that is not in the paper gives the approximate coordinates of SNe images in MegaCam focal plane. They are needed to estimate the filter transmission function. This data can also be downloaded at the University of Toronto's Research Repository https://tspace.library.utoronto.ca/handle/1807/24512 (3 data files).

  14. Timescale stretch parameterization of Type Ia supernova B-band light curves

    SciTech Connect

    Goldhaber, G.; Groom, D.E.; Kim, A.; Aldering, G.; Astier, P.; Conley, A.; Deustua, S.E.; Ellis, R.; Fabbro, S.; Fruchter, A.S.; Goobar, A.; Hook, I.; Irwin, M.; Kim, M.; Knop, R.A.; Lidman, C.; McMahon, R.; Nugent, P.E.; Pain, R.; Panagia, N.; Pennypacker, C.R.; Perlmutter, S.; Ruiz-Lapuente, P.; Schaefer, B.; Walton, N.A.; York, T.

    2001-04-01

    R-band intensity measurements along the light curve of Type Ia supernovae discovered by the Cosmology Project (SCP) are fitted in brightness to templates allowing a free parameter the time-axis width factor w identically equal to s times (1+z). The data points are then individually aligned in the time-axis, normalized and K-corrected back to the rest frame, after which the nearly 1300 normalized intensity measurements are found to lie on a well-determined common rest-frame B-band curve which we call the ''composite curve.'' The same procedure is applied to 18 low-redshift Calan/Tololo SNe with Z < 0.11; these nearly 300 B-band photometry points are found to lie on the composite curve equally well. The SCP search technique produces several measurements before maximum light for each supernova. We demonstrate that the linear stretch factor, s, which parameterizes the light-curve timescale appears independent of z, and applies equally well to the declining and rising parts of the light curve. In fact, the B band template that best fits this composite curve fits the individual supernova photometry data when stretched by a factor s with chi 2/DoF {approx} 1, thus as well as any parameterization can, given the current data sets. The measurement of the data of explosion, however, is model dependent and not tightly constrained by the current data. We also demonstrate the 1 + z light-cure time-axis broadening expected from cosmological expansion. This argues strongly against alternative explanations, such as tired light, for the redshift of distant objects.

  15. TYPE Ia SUPERNOVA CARBON FOOTPRINTS

    SciTech Connect

    Thomas, R. C.; Nugent, P.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Hsiao, E. Y.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Paech, K.; Chotard, N.; Copin, Y.; Gangler, E.; and others

    2011-12-10

    We present convincing evidence of unburned carbon at photospheric velocities in new observations of five Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 days relative to maximum. Detections are based on the presence of relatively strong C II {lambda}6580 absorption 'notches' in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the five SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibit high-velocity (v > 20, 000 km s{sup -1}) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broadband light curve/color behavior: three of the five have relatively narrow light curves but also blue colors and a fourth may be a dust-reddened member of this family. Accounting for signal to noise and phase, we estimate that 22{sup +10}{sub -6%} of SNe Ia exhibit spectroscopic C II signatures as late as -5 days with respect to maximum. We place these new objects in the context of previously recognized carbon-positive SNe Ia and consider reasonable scenarios seeking to explain a physical connection between light curve properties and the presence of photospheric carbon. We also examine the detailed evolution of the detected carbon signatures and the surrounding wavelength regions to shed light on the distribution of carbon in the ejecta. Our ability to reconstruct the C II {lambda}6580 feature in detail under the assumption of purely spherical symmetry casts doubt on a 'carbon blobs' hypothesis, but does not rule out all asymmetric models. A low volume filling factor for carbon, combined with line-of-sight effects, seems unlikely to explain the scarcity of detected carbon in SNe Ia by itself.

  16. SALT spectroscopic classification of PS16atu (SN 2016atv) as a type-Ia supernova after maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Kotze, M.

    2016-03-01

    We obtained SALT (+RSS) spectroscopy of PS16atu (SN 2016atv) on 2016 Mar 10.1 UT, covering the wavelength range 350-920 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows PS16atu is a type-Ia supernova approximately a week past maximum light.

  17. Constraints on shallow {sup 56}Ni from the early light curves of type Ia supernovae

    SciTech Connect

    Piro, Anthony L.

    2014-03-20

    Ongoing transient surveys are presenting an unprecedented account of the rising light curves of Type Ia supernovae (SNe Ia). This early emission probes the shallowest layers of the exploding white dwarf (WD), which can provide constraints on the progenitor star and the properties of the explosive burning. We use semianalytic models of radioactively powered rising light curves to analyze these observations. As we have summarized in previous work, the main limiting factor in determining the surface distribution of {sup 56}Ni is the lack of an unambiguously identified time of explosion, as would be provided by detection of shock breakout or shock-heated cooling. Without this the SN may in principle exhibit a 'dark phase' for a few hours to days, where the only emission is from shock-heated cooling that is too dim to be detected. We show that by assuming a theoretically motivated time-dependent velocity evolution, the explosion time can be better constrained, albeit with potential systematic uncertainties. This technique is used to infer the surface {sup 56}Ni distributions of three recent SNe Ia that were caught especially early in their rise. In all three we find fairly similar {sup 56}Ni distributions. Observations of SN 2011fe and SN 2012cg probe shallower depths than SN 2009ig, and in these two cases {sup 56}Ni is present merely ∼10{sup –2} M {sub ☉} from the WDs' surfaces. The uncertainty in this result is up to an order of magnitude given the difficulty of precisely constraining the explosion time. We also use our conclusions about the explosion times to reassess radius constraints for the progenitor of SN 2011fe, as well as discuss the roughly t {sup 2} power law that is inferred for many observed rising light curves.

  18. The Sloan Digital Sky Survey-II: Photometry and Supernova Ia Light Curves from the 2005 Data

    SciTech Connect

    Holtzman, Jon A.; Marriner, John; Kessler, Richard; Sako, Masao; Dilday, Ben; Frieman, Joshua A.; Schneider, Donald P.; Bassett, Bruce; Becker, Andrew; Cinabro, David; DeJongh, Fritz; Depoy, Darren L.; Doi, Mamoru; Garnavich, Peter M.; Hogan, Craig J.; Jha, Saurabh; Konishi, Kohki; Lampeitl, Hubert; Marshall, Jennifer L.; McGinnis, David; Miknaitis, Gajus; /KICP, Chicago /Portsmouth U., ICG /Ohio State U., Dept. Astron. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Rochester Inst. Tech. /KIPAC, Menlo Park /Portsmouth U., ICG /Tokyo U., Inst. Astron. /South African Astron. Observ. /Cape Town U. /Tokyo U., ICRR /KIPAC, Menlo Park

    2010-08-26

    We present ugriz light curves for 146 spectroscopically confirmed or spectroscopically probable Type Ia supernovae from the 2005 season of the SDSS-II Supernova survey. The light curves have been constructed using a photometric technique that we call scene modeling, which is described in detail here; the major feature is that supernova brightnesses are extracted from a stack of images without spatial resampling or convolution of the image data. This procedure produces accurate photometry along with accurate estimates of the statistical uncertainty, and can be used to derive photometry taken with multiple telescopes. We discuss various tests of this technique that demonstrate its capabilities. We also describe the methodology used for the calibration of the photometry, and present calibrated magnitudes and fluxes for all of the spectroscopic SNe Ia from the 2005 season.

  19. Exploring the Potential Diversity of Early Type Ia Supernova Light Curves

    NASA Astrophysics Data System (ADS)

    Piro, Anthony L.; Morozova, Viktoriya S.

    2016-07-01

    During the first several days after explosion, Type Ia supernova light curves probe the outer layers of the exploding star, and therefore provide important clues for identifying their progenitors. We investigate how both the shallow 56Ni distribution and the presence of circumstellar material shape these early light curves. This is performed using a series of numerical experiments with parameterized properties for systematic exploration. Although not all of the considered models may be realized in nature (and indeed there are arguments why some of them should not occur), the spirit of this work is to provide a broader exploration of the diversity of possibilities. We find that shallower 56Ni leads to steeper, bluer light curves. Differences in the shape of the rise can introduce errors in estimating the explosion time, and thus impact efforts to infer upper limits on the progenitor or companion radius from a lack of observed shock cooling emission. Circumstellar material can lead to significant luminosity during the first few days, but its presence can be difficult to identify depending on the degree of nickel mixing. In some cases, the hot emission of circumstellar material may even lead to a signature similar to an interaction with a companion, and thus in the future additional diagnostics should be gathered for properly assessing early light curves.

  20. Integration of Near-Maximum-Light Type Ia Supernova Spectra as a Method of High-z Identification

    NASA Astrophysics Data System (ADS)

    Troxel, M. A.; Ketchum, W. R.; Branch, D.; Garnavich, P.; Baron, E.; Wang, Y.

    2005-12-01

    Spectral identification of Type Ia supernovae (SNe Ia) has been limited in the past to approximately z = 1.7 due to noise. In order to extend this limit and allow identification of higher-z SNe Ia, we use a simple integration technique to sum near-maximum-light spectra weighted according to their relative fluxes. We show that this combination of near-maximum spectra statistically increases the available signal to noise ratio while preserving not only the signature spectral features of SNe Ia, but also the more specific spectral features that identify sub-types of SNe Ia. In the cases of some peculiar SNe Ia, the unique identity of the supernovae being integrated is preserved as well. This increases the redshift at which SNe Ia, used as standard candles in cosmology, can be identified and thus increases our ability to probe the expansion history of the universe. This work has been supported by NSF grants AST-0204771 and AST-0506028, and NASA grant NNG04GD36G.

  1. Progenitor's Signatures in Type Ia Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Chiotellis, A.; Kosenko, D.; Schure, K. M.; Vink, J.

    2013-01-01

    The remnants of Type Ia supernovae (SNe Ia) can provide important clues about their progenitor histories. We discuss two well-observed supernova remnants (SNRs) that are believed to have resulted from SNe Ia, and use various tools to shed light on the possible progenitor histories. We find that Kepler's SNR is consistent with a symbiotic binary progenitor consisting of a white dwarf and an AGB star. Our hydrosimulations can reproduce the observed kinematic and morphological properties. For Tycho's remnant we use the characteristics of the X-ray spectrum and kinematics to show that the ejecta has likely interacted with dense circumstellar gas.

  2. Defining photometric peculiar type Ia supernovae

    SciTech Connect

    González-Gaitán, S.; Pignata, G.; Förster, F.; Gutiérrez, C. P.; Bufano, F.; Galbany, L.; Hamuy, M.; De Jaeger, T.; Hsiao, E. Y.; Phillips, M. M.; Folatelli, G.; Anderson, J. P.

    2014-11-10

    We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e., objects with light curve characteristics such as later primary maxima and the absence of a secondary peak in redder filters. This method is capable of selecting this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have photometric characteristics similar to 91bg-like SNe Ia, namely, the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large upcoming wide-field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

  3. Against the Wind: Radio Light Curves of Type Ia Supernovae Interacting with Low-density Circumstellar Shells

    NASA Astrophysics Data System (ADS)

    Harris, Chelsea E.; Nugent, Peter E.; Kasen, Daniel N.

    2016-06-01

    For decades a wide variety of observations spanning the radio through optical and on to the X-ray have attempted to uncover signs of type Ia supernovae (SNe Ia) interacting with a circumstellar medium (CSM). The goal of these studies is to constrain the nature of the hypothesized SN Ia mass-donor companion. A continuous CSM is typically assumed when interpreting observations of interaction. However, while such models have been successfully applied to core-collapse SNe, the assumption of continuity may not be accurate for SNe Ia, because shells of CSM could be formed by pre-supernova eruptions (novae). In this work, we model the interaction of SNe with a spherical, low-density, finite-extent CSM and create a suite of synthetic radio synchrotron light curves. We find that CSM shells produce sharply peaked light curves. We also identify a fiducial set of models that obey a common evolution and can be used to generate radio light curves for an interaction with an arbitrary shell. The relations obeyed by the fiducial models can be used to deduce CSM properties from radio observations; we demonstrate this by applying them to the nondetections of SN 2011fe and SN 2014J. Finally, we explore a multiple shell CSM configuration and describe its more complicated dynamics and the resultant radio light curves.

  4. ESTIMATING THE FIRST-LIGHT TIME OF THE TYPE IA SUPERNOVA 2014J IN M82

    SciTech Connect

    Zheng, WeiKang; Shivvers, Isaac; Filippenko, Alexei V.; Clubb, Kelsey I.; Fox, Ori D.; Graham, Melissa L.; Kelly, Patrick L.; Mauerhan, Jon C.; Itagaki, Koichi

    2014-03-01

    The Type Ia supernova (SN Ia) 2014J in M82 (d ≈ 3.5 Mpc) was serendipitously discovered by S. Fossey's group on 2014 January 21 UT and has been confirmed to be the nearest known SN Ia since at least SN 1986G. Although SN 2014J was not discovered until ∼7 days after first light, both the Katzman Automatic Imaging Telescope at Lick Observatory and K. Itagaki obtained several prediscovery observations of SN 2014J. With these data, we are able to constrain the object's time of first light to be January 14.75 UT, only 0.82 ± 0.21 days before our first detection. Interestingly, we find that the light curve is well described by a varying power law, much like SN 2013dy, which makes SN 2014J the second example of a changing power law in early-time SN Ia light curves. A low-resolution spectrum taken on January 23.388 UT, ∼8.70 days after first light, shows that SN 2014J is a heavily reddened but otherwise spectroscopically normal SN Ia.

  5. New approaches for modeling type Ia supernovae

    SciTech Connect

    Zingale, Michael; Almgren, Ann S.; Bell, John B.; Day, Marcus S.; Rendleman, Charles A.; Woosley, Stan

    2007-06-25

    Type Ia supernovae (SNe Ia) are the largest thermonuclearexplosions in the Universe. Their light output can be seen across greatstances and has led to the discovery that the expansion rate of theUniverse is accelerating. Despite the significance of SNe Ia, there arestill a large number of uncertainties in current theoretical models.Computational modeling offers the promise to help answer the outstandingquestions. However, even with today's supercomputers, such calculationsare extremely challenging because of the wide range of length and timescales. In this paper, we discuss several new algorithms for simulationsof SNe Ia and demonstrate some of their successes.

  6. Progenitors of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Maeda, Keiichi; Terada, Yukikatsu

    2016-07-01

    Natures of progenitors of type Ia Supernovae (SNe Ia) have not yet been clarified. There has been long and intensive discussion on whether the so-called single degenerate (SD) scenario or the double degenerate (DD) scenario, or anything else, could explain a major population of SNe Ia, but the conclusion has not yet been reached. With rapidly increasing observational data and new theoretical ideas, the field of studying the SN Ia progenitors has been quickly developing, and various new insights have been obtained in recent years. This paper aims at providing a summary of the current situation regarding the SN Ia progenitors, both in theory and observations. It seems difficult to explain the emerging diversity seen in observations of SNe Ia by a single population, and we emphasize that it is important to clarify links between different progenitor scenarios and different sub-classes of SNe Ia.

  7. Diffuse gas in galaxies sheds new light on the origin of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Johansson, Jonas; Woods, Tyrone E.; Gilfanov, Marat; Sarzi, Marc; Chen, Yan-Mei; Oh, Kyuseok

    2014-08-01

    We measure the strength of He II λ4686 nebular emission in passively evolving (`retired') galaxies, aiming to constrain their populations of hot accreting white dwarfs (WDs) in the context of the single-degenerate (SD) scenario of Type Ia supernovae (SNe Ia). In the SD scenario, as a WD burns hydrogen-rich material accreted from a companion star, it becomes a powerful source of ionizing ultraviolet emission. If significant populations of such sources exist in galaxies, strong emission in the recombination lines of He II should be expected from the interstellar medium. To explore this conjecture, we select from the Sloan Digital Sky Survey ˜11 500 emission-line galaxies with stellar ages >1 Gyr showing no signs of active galactic nuclei activity and co-add their spectra in bins of stellar population age. For the first time, we detect He II λ4686 nebular emission in retired galaxies and find it to be significantly weaker than that expected in the SD scenario, especially in the youngest age bin (1-4 Gyr) where the SN Ia rate is the highest. Instead, the strength of the observed He II λ4686 nebular emission is consistent with post-asymptotic giant branch stars being the sole ionizing source in all age bins. These results limit populations of accreting WDs with photospheric temperatures (Teff) in the range ˜(1.5-6) × 105 K to the level at which they can account for no more than ˜5-10 per cent of the observed SN Ia rate. Conversely, should all WD progenitors of SN Ia go through the phase of steady nuclear burning with Teff ˜ (1.5-6) × 105 K, they do not increase their mass by more than ˜0.03 M⊙ in this regime.

  8. Light Curves of 213 Type Ia Supernovae from the ESSENCE Survey

    NASA Astrophysics Data System (ADS)

    Narayan, G.; Rest, A.; Tucker, B. E.; Foley, R. J.; Wood-Vasey, W. M.; Challis, P.; Stubbs, C.; Kirshner, R. P.; Aguilera, C.; Becker, A. C.; Blondin, S.; Clocchiatti, A.; Covarrubias, R.; Damke, G.; Davis, T. M.; Filippenko, A. V.; Ganeshalingam, M.; Garg, A.; Garnavich, P. M.; Hicken, M.; Jha, S. W.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miknaitis, G.; Pignata, G.; Prieto, J. L.; Riess, A. G.; Schmidt, B. P.; Silverman, J. M.; Smith, R. C.; Sollerman, J.; Spyromilio, J.; Suntzeff, N. B.; Tonry, J. L.; Zenteno, A.

    2016-05-01

    The ESSENCE survey discovered 213 Type Ia supernovae at redshifts 0.1\\lt z\\lt 0.81 between 2002 and 2008. We present their R- and I-band photometry, measured from images obtained using the MOSAIC II camera at the CTIO Blanco, along with rapid-response spectroscopy for each object. We use our spectroscopic follow-up observations to determine an accurate, quantitative classification, and precise redshift. Through an extensive calibration program we have improved the precision of the CTIO Blanco natural photometric system. We use several empirical metrics to measure our internal photometric consistency and our absolute calibration of the survey. We assess the effect of various potential sources of systematic bias on our measured fluxes, and estimate the dominant term in the systematic error budget from the photometric calibration on our absolute fluxes is ∼1%.

  9. The Union3 Supernova Ia Compilation

    NASA Astrophysics Data System (ADS)

    Rubin, David; Aldering, Greg Scott; Amanullah, Rahman; Barbary, Kyle H.; Bruce, Adam; Chappell, Greta; Currie, Miles; Dawson, Kyle S.; Deustua, Susana E.; Doi, Mamoru; Fakhouri, Hannah; Fruchter, Andrew S.; Gibbons, Rachel A.; Goobar, Ariel; Hsiao, Eric; Huang, Xiaosheng; Ihara, Yutaka; Kim, Alex G.; Knop, Robert A.; Kowalski, Marek; Krechmer, Evan; Lidman, Chris; Linder, Eric; Meyers, Joshua; Morokuma, Tomoki; Nordin, Jakob; Perlmutter, Saul; Ripoche, Pascal; Ruiz-Lapuente, Pilar; Rykoff, Eli S.; Saunders, Clare; Spadafora, Anthony L.; Suzuki, Nao; Takanashi, Naohiro; Yasuda, Naoki; Supernova Cosmology Project

    2016-01-01

    High-redshift supernovae observed with the Hubble Space Telescope (HST) are crucial for constraining any time variation in dark energy. In a forthcoming paper (Rubin+, in prep), we will present a cosmological analysis incorporating existing supernovae with improved calibrations, and new HST-observed supernovae (six above z=1). We combine these data with current literature data, and fit them using SALT2-4 to create the Union3 Supernova compilation. We build on the Unified Inference for Type Ia cosmologY (UNITY) framework (Rubin+ 2015b), incorporating non-linear light-curve width and color relations, a model for unexplained dispersion, an outlier model, and a redshift-dependent host-mass correction.

  10. Type Ia supernovae as standard candles

    NASA Technical Reports Server (NTRS)

    Branch, David; Miller, Douglas L.

    1993-01-01

    The distribution of absolute blue magnitudes among Type Ia supernovae (SNs Ia) is studied. Supernovae were used with well determined apparent magnitudes at maximum light and parent galaxies with relative distances determined by the Tully-Fisher or Dn - sigma techniques. The mean absolute blue magnitude is given and the observational dispersion is only sigma(MB) 0.36, comparable to the expected combined errors in distance, apparent magnitude, and extinction. The mean (B-V) color at maximum light is 0.03 +/- 0.04, with a dispersion sigma(B-V) = 0.20. The Cepheid-based distance to IC 4182, the parent galaxy of the normal and unextinguished Type Ia SN 1937C, leads to a Hubble constant of H(0) + 51 +/- 12 km/s Mpc. The existence of a few SNs Ia that appear to have been reddened and dimmed by dust in their parent galaxies does not seriously compromise the use of SNs Ia as distance indicators.

  11. THE SPECTROSCOPIC DIVERSITY OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Blondin, S.; Kirshner, R. P.; Mandel, K. S.; Challis, P.; Berlind, P.; Calkins, M.; Garnavich, P. M.; Jha, S. W.; Modjaz, M.; Riess, A. G.; Schmidt, B. P.

    2012-05-15

    We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993-2008 through the Center for Astrophysics Supernova Program. There are on average eight spectra for each of the 313 SNe Ia with at least two spectra. Most of the spectra were obtained with the FAST spectrograph at the Fred Lawrence Whipple Observatory 1.5 m telescope and reduced in a consistent manner, making this data set well suited for studies of SN Ia spectroscopic diversity. Using additional data from the literature, we study the spectroscopic and photometric properties of SNe Ia as a function of spectroscopic class using the classification schemes of Branch et al. and Wang et al. The width-luminosity relation appears to be steeper for SNe Ia with broader lines, although the result is not statistically significant with the present sample. Based on the evolution of the characteristic Si II {lambda}6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from {approx}0 to {approx}400 km s{sup -1} day{sup -1} considering the instantaneous velocity decline rate at maximum light. We find a weaker and less significant correlation between Si II velocity and intrinsic B - V color at maximum light than reported by Foley et al., owing to a more comprehensive treatment of uncertainties and host galaxy dust. We study the extent of nuclear burning and the presence of unburnt carbon in the outermost layers of the ejecta and report new detections of C II {lambda}6580 in 23 early-time SN Ia spectra. The frequency of C II detections is not higher in SNe Ia with bluer colors or narrower light curves, in conflict with the recent results of Thomas et al. Based on nebular spectra of 27 SNe Ia, we find no relation between the FWHM of the iron emission feature at {approx}4700 A and {Delta}m{sub 15}(B) after removing the two low-luminosity SN 1986G and SN 1991bg, suggesting that the

  12. THE LOCAL HOSTS OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Neill, James D.; Martin, D. Christopher; Barlow, Tom A.; Foster, Karl; Friedman, Peter G.; Morrissey, Patrick; Wyder, Ted K.; Sullivan, Mark; Howell, D. Andrew; Conley, Alex; Seibert, Mark; Madore, Barry F.; Neff, Susan G.; Schiminovich, David; Bianchi, Luciana; Donas, Jose; Milliard, Bruno; Heckman, Timothy M.; Lee, Young-Wook; Rich, R. Michael

    2009-12-20

    We use multi-wavelength, matched aperture, integrated photometry from the Galaxy Evolution Explorer (GALEX), the Sloan Digital Sky Survey, and the RC3 to estimate the physical properties of 166 nearby galaxies hosting 168 well-observed Type Ia supernovae (SNe Ia). The ultraviolet (UV) imaging of local SN Ia hosts from GALEX allows a direct comparison with higher-redshift hosts measured at optical wavelengths that correspond to the rest-frame UV. Our data corroborate well-known features that have been seen in other SN Ia samples. Specifically, hosts with active star formation produce brighter and slower SNe Ia on average, and hosts with luminosity-weighted ages older than 1 Gyr produce on average more faint, fast, and fewer bright, slow SNe Ia than younger hosts. New results include that in our sample, the faintest and fastest SNe Ia occur only in galaxies exceeding a stellar mass threshold of approx10{sup 10} M{sub sun}, leading us to conclude that their progenitors must arise in populations that are older and/or more metal rich than the general SN Ia population. A low host extinction subsample hints at a residual trend in peak luminosity with host age, after correcting for light-curve shape, giving the appearance that older hosts produce less-extincted SNe Ia on average. This has implications for cosmological fitting of SNe Ia, and suggests that host age could be useful as a parameter in the fitting. Converting host mass to metallicity and computing {sup 56}Ni mass from the supernova light curves, we find that our local sample is consistent with a model that predicts a shallow trend between stellar metallicity and the {sup 56}Ni mass that powers the explosion, but we cannot rule out the absence of a trend. We measure a correlation between {sup 56}Ni mass and host age in the local universe that is shallower and not as significant as that seen at higher redshifts. The details of the age-{sup 56}Ni mass correlations at low and higher redshift imply a luminosity

  13. Ultraviolet diversity of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Foley, Ryan J.; Pan, Yen-Chen; Brown, P.; Filippenko, A. V.; Fox, O. D.; Hillebrandt, W.; Kirshner, R. P.; Marion, G. H.; Milne, P. A.; Parrent, J. T.; Pignata, G.; Stritzinger, M. D.

    2016-09-01

    Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blueward of 2900 Å. We focus on spectra taken within 5 d of maximum brightness. Our sample of 10 SNe Ia spans, the majority of the parameter space of SN Ia optical diversity. We find that SNe Ia have significantly more diversity in the UV than in the optical, with the spectral variance continuing to increase with decreasing wavelengths until at least 1800 Å (the limit of our data). The majority of the UV variance correlates with optical light-curve shape, while there are no obvious and unique correlations between spectral shape and either ejecta velocity or host-galaxy morphology. Using light-curve shape as the primary variable, we create a UV spectral model for SNe Ia at peak brightness. With the model, we can examine how individual SNe vary relative to expectations based on only their light-curve shape. Doing this, we confirm an excess of flux for SN 2011fe at short wavelengths, consistent with its progenitor having a subsolar metallicity. While most other SNe Ia do not show large deviations from the model, ASASSN-14lp has a deficit of flux at short wavelengths, suggesting that its progenitor was relatively metal rich.

  14. SPECTROSCOPY OF TYPE Ia SUPERNOVAE BY THE CARNEGIE SUPERNOVA PROJECT

    SciTech Connect

    Folatelli, Gaston; Morrell, Nidia; Phillips, Mark M.; Hsiao, Eric; Campillay, Abdo; Contreras, Carlos; Castellon, Sergio; Roth, Miguel; Hamuy, Mario; Anderson, Joseph P.; Krzeminski, Wojtek; Stritzinger, Maximilian; Burns, Christopher R.; Freedman, Wendy L.; Madore, Barry F.; Murphy, David; Persson, S. E.; Prieto, Jose L.; Suntzeff, Nicholas B.; Krisciunas, Kevin; and others

    2013-08-10

    This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature, we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts and pseudo-equivalent widths (pW). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely, SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further study the correlations between spectroscopic and photometric parameters such as light-curve decline rate and color. In agreement with previous studies, we find that the pW of Si II absorption features are very good indicators of light-curve decline rate. Furthermore, we demonstrate that parameters such as pW2 (Si II 4130) and pW6 (Si II 5972) provide precise calibrations of the peak B-band luminosity with dispersions of Almost-Equal-To 0.15 mag. In the search for a secondary parameter in the calibration of peak luminosity for SNe Ia, we find a Almost-Equal-To 2{sigma}-3{sigma} correlation between B-band Hubble residuals and the velocity at maximum light of S II and Si II lines.

  15. TYPE Ia SUPERNOVA DISTANCE MODULUS BIAS AND DISPERSION FROM K-CORRECTION ERRORS: A DIRECT MEASUREMENT USING LIGHT CURVE FITS TO OBSERVED SPECTRAL TIME SERIES

    SciTech Connect

    Saunders, C.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Kim, A. G.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Chotard, N.; Copin, Y.; Gangler, E.; and others

    2015-02-10

    We estimate systematic errors due to K-corrections in standard photometric analyses of high-redshift Type Ia supernovae. Errors due to K-correction occur when the spectral template model underlying the light curve fitter poorly represents the actual supernova spectral energy distribution, meaning that the distance modulus cannot be recovered accurately. In order to quantify this effect, synthetic photometry is performed on artificially redshifted spectrophotometric data from 119 low-redshift supernovae from the Nearby Supernova Factory, and the resulting light curves are fit with a conventional light curve fitter. We measure the variation in the standardized magnitude that would be fit for a given supernova if located at a range of redshifts and observed with various filter sets corresponding to current and future supernova surveys. We find significant variation in the measurements of the same supernovae placed at different redshifts regardless of filters used, which causes dispersion greater than ∼0.05 mag for measurements of photometry using the Sloan-like filters and a bias that corresponds to a 0.03 shift in w when applied to an outside data set. To test the result of a shift in supernova population or environment at higher redshifts, we repeat our calculations with the addition of a reweighting of the supernovae as a function of redshift and find that this strongly affects the results and would have repercussions for cosmology. We discuss possible methods to reduce the contribution of the K-correction bias and uncertainty.

  16. Type Ia supernova rate studies from the SDSS-II Supernova Study

    SciTech Connect

    Dilday, Benjamin

    2008-08-01

    The author presents new measurements of the type Ia SN rate from the SDSS-II Supernova Survey. The SDSS-II Supernova Survey was carried out during the Fall months (Sept.-Nov.) of 2005-2007 and discovered ~ 500 spectroscopically confirmed SNe Ia with densely sampled (once every ~ 4 days), multi-color light curves. Additionally, the SDSS-II Supernova Survey has discovered several hundred SNe Ia candidates with well-measured light curves, but without spectroscopic confirmation of type. This total, achieved in 9 months of observing, represents ~ 15-20% of the total SNe Ia discovered worldwide since 1885. The author describes some technical details of the SN Survey observations and SN search algorithms that contributed to the extremely high-yield of discovered SNe and that are important as context for the SDSS-II Supernova Survey SN Ia rate measurements.

  17. Luminosity distributions of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Ashall, C.; Mazzali, P.; Sasdelli, M.; Prentice, S. J.

    2016-08-01

    We have assembled a dataset of 165 low redshift, $z<$0.06, publicly available type Ia supernovae (SNe Ia). We produce maximum light magnitude ($M_{B}$ and $M_{V}$) distributions of SNe Ia to explore the diversity of parameter space that they can fill. Before correction for host galaxy extinction we find that the mean $M_{B}$ and $M_{V}$ of SNe Ia are $-18.58\\pm0.07$mag and $-18.72\\pm0.05$mag respectively. Host galaxy extinction is corrected using a new method based on the SN spectrum. After correction, the mean values of $M_{B}$ and $M_{V}$ of SNe Ia are $-19.10\\pm0.06$ and $-19.10\\pm0.05$mag respectively. After correction for host galaxy extinction, `normal' SNeIa ($\\Delta m_{15}(B)<1.6$mag) fill a larger parameter space in the Width-Luminosity Relation (WLR) than previously suggested, and there is evidence for luminous SNe Ia with large $\\Delta m_{15}(B)$. We find a bimodal distribution in $\\Delta m_{15}(B)$, with a pronounced lack of transitional events at $\\Delta m_{15}(B)$=1.6 mag. We confirm that faster, low-luminosity SNe tend to come from passive galaxies. Dividing the sample by host galaxy type, SNe Ia from star-forming (S-F) galaxies have a mean $M_{B}=-19.20 \\pm 0.05$ mag, while SNe Ia from passive galaxies have a mean $M_{B}=-18.57 \\pm 0.24$ mag. Even excluding fast declining SNe, `normal' ($M_{B}<-18$ mag) SNe Ia from S-F and passive galaxies are distinct. In the $V$-band, there is a difference of 0.4$ \\pm $0.13 mag between the median ($M_{V}$) values of the `normal' SN Ia population from passive and S-F galaxies. This is consistent with ($\\sim 15 \\pm $10)% of `normal' SNe Ia from S-F galaxies coming from an old stellar population.

  18. Luminosity distributions of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Ashall, C.; Mazzali, P.; Sasdelli, M.; Prentice, S. J.

    2016-08-01

    We have assembled a data set of 165 low redshift, z < 0.06, publicly available Type Ia supernovae (SNe Ia). We produce maximum light magnitude (MB and MV) distributions of SNe Ia to explore the diversity of parameter space that they can fill. Before correction for host galaxy extinction we find that the mean MB and MV of SNe Ia are -18.58 ± 0.07 and -18.72 ± 0.05 mag, respectively. Host galaxy extinction is corrected using a new method based on the SN spectrum. After correction, the mean values of MB and MV of SNe Ia are -19.10 ± 0.06 and -19.10 ± 0.05 mag, respectively. After correction for host galaxy extinction, `normal' SNe Ia (Δm15(B) < 1.6 mag) fill a larger parameter space in the width-luminosity relation than previously suggested, and there is evidence for luminous SNe Ia with large Δm15(B). We find a bimodal distribution in Δm15(B), with a pronounced lack of transitional events at Δm15(B) = 1.6 mag. We confirm that faster, low-luminosity SNe tend to come from passive galaxies. Dividing the sample by host galaxy type, SNe Ia from star-forming (S-F) galaxies have a mean MB = -19.20 ± 0.05 mag, while SNe Ia from passive galaxies have a mean MB = -18.57 ± 0.24 mag. Even excluding fast declining SNe, `normal' (MB < -18 mag) SNe Ia from S-F and passive galaxies are distinct. In the V band, there is a difference of 0.4 ± 0.13 mag between the median (MV) values of the `normal' SN Ia population from passive and S-F galaxies. This is consistent with (˜15 ± 10) per cent of `normal' SNe Ia from S-F galaxies coming from an old stellar population.

  19. K-corrections and extinction corrections for Type Ia supernovae

    SciTech Connect

    Nugent, Peter; Kim, Alex; Perlmutter, Saul

    2002-05-21

    The measurement of the cosmological parameters from Type Ia supernovae hinges on our ability to compare nearby and distant supernovae accurately. Here we present an advance on a method for performing generalized K-corrections for Type Ia supernovae which allows us to compare these objects from the UV to near-IR over the redshift range 0 < z < 2. We discuss the errors currently associated with this method and how future data can improve upon it significantly. We also examine the effects of reddening on the K-corrections and the light curves of Type Ia supernovae. Finally, we provide a few examples of how these techniques affect our current understanding of a sample of both nearby and distant supernovae.

  20. Rates and progenitors of type Ia supernovae

    SciTech Connect

    Wood-Vasey, William Michael

    2004-08-16

    The remarkable uniformity of Type Ia supernovae has allowed astronomers to use them as distance indicators to measure the properties and expansion history of the Universe. However, Type Ia supernovae exhibit intrinsic variation in both their spectra and observed brightness. The brightness variations have been approximately corrected by various methods, but there remain intrinsic variations that limit the statistical power of current and future observations of distant supernovae for cosmological purposes. There may be systematic effects in this residual variation that evolve with redshift and thus limit the cosmological power of SN Ia luminosity-distance experiments. To reduce these systematic uncertainties, we need a deeper understanding of the observed variations in Type Ia supernovae. Toward this end, the Nearby Supernova Factory has been designed to discover hundreds of Type Ia supernovae in a systematic and automated fashion and study them in detail. This project will observe these supernovae spectrophotometrically to provide the homogeneous high-quality data set necessary to improve the understanding and calibration of these vital cosmological yardsticks. From 1998 to 2003, in collaboration with the Near-Earth Asteroid Tracking group at the Jet Propulsion Laboratory, a systematic and automated searching program was conceived and executed using the computing facilities at Lawrence Berkeley National Laboratory and the National Energy Research Supercomputing Center. An automated search had never been attempted on this scale. A number of planned future large supernovae projects are predicated on the ability to find supernovae quickly, reliably, and efficiently in large datasets. A prototype run of the SNfactory search pipeline conducted from 2002 to 2003 discovered 83 SNe at a final rate of 12 SNe/month. A large, homogeneous search of this scale offers an excellent opportunity to measure the rate of Type Ia supernovae. This thesis presents a new method for

  1. Rates and progenitors of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Wood-Vasey, William Michael

    The remarkable uniformity of Type Ia supernovae has allowed astronomers to use them as distance indicators to measure the properties and expansion history of the Universe. However, Type Ia supernovae exhibit intrinsic variation in both their spectra and observed brightness. The brightness variations have been approximately corrected by various methods, but there remain intrinsic variations that limit the statistical power of current and future observations of distant supernovae for cosmological purposes. There may be systematic effects in this residual variation that evolve with redshift and thus limit the cosmological power of SN Ia luminosity-distance experiments. To reduce these systematic uncertainties, we need a deeper understanding of the observed variations in Type Ia supernovae. Toward this end, the Nearby Supernova Factory has been designed to discover hundreds of Type Ia supernovae in a systematic and automated fashion and study them in detail. This project will observe these supernovae spectrophotometrically to provide the homogeneous high-quality data set necessary to improve the understanding and calibration of these vital cosmological yardsticks. >From 1998 to 2003, in collaboration with the Near-Earth Asteroid Tracking group at the Jet Propulsion Laboratory, a systematic and automated searching program was conceived and executed using the computing facilities at Lawrence Berkeley National Laboratory and the National Energy Research Supercomputing Center. An automated search had never been attempted on this scale. A number of planned future large supernovae projects are predicated on the ability to find supernovae quickly, reliably, and efficiently in large datasets. A prototype run of the SNfactory search pipeline conducted from 2002 to 2003 discovered 83 SNe at a final rate of 12 SNe/month. A large, homogeneous search of this scale offers an excellent opportunity to measure the rate of Type Ia supernovae. This thesis presents a new method for

  2. SALT spectroscopic classification of LSQ16acz (= PS16bby = SN 2016bew) as a type-Ia supernova approaching maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Kotze, M.

    2016-03-01

    We obtained SALT (+RSS) spectroscopy of LSQ16acz (= PS16bby = SN 2016bew; Baltay et al. 2013, PASP, 125, 683) on 2016 Mar 14.9 UT, covering the wavelength range 340-920 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows LSQ16acz is a type-Ia supernova a few days before maximum light.

  3. The Carnegie Supernova Project: Intrinsic colors of type Ia supernovae

    SciTech Connect

    Burns, Christopher R.; Persson, S. E.; Freedman, Wendy L.; Madore, Barry F.; Stritzinger, Maximilian; Contreras, Carlos; Phillips, M. M.; Hsiao, E. Y.; Boldt, Luis; Campillay, Abdo; Castellón, Sergio; Morrell, Nidia; Salgado, Francisco; Folatelli, Gaston; Suntzeff, Nicholas B.

    2014-07-01

    We present an updated analysis of the intrinsic colors of Type Ia supernova (SNe Ia) using the latest data release of the Carnegie Supernova Project. We introduce a new light-curve parameter very similar to stretch that is better suited for fast-declining events, and find that these peculiar types can be seen as extensions to the population of 'normal' SNe Ia. With a larger number of objects, an updated fit to the Lira relation is presented along with evidence for a dependence on the late-time slope of the B – V light-curves with stretch and color. Using the full wavelength range from u to H band, we place constraints on the reddening law for the sample as a whole and also for individual events/hosts based solely on the observed colors. The photometric data continue to favor low values of R{sub V} , though with large variations from event to event, indicating an intrinsic distribution. We confirm the findings of other groups that there appears to be a correlation between the derived reddening law, R{sub V} , and the color excess, E(B – V), such that larger E(B – V) tends to favor lower R{sub V} . The intrinsic u-band colors show a relatively large scatter that cannot be explained by variations in R{sub V} or by the Goobar power-law for circumstellar dust, but rather is correlated with spectroscopic features of the supernova and is therefore likely due to metallicity effects.

  4. Type Ia supernovae: their origin and possible applications in cosmology.

    PubMed

    Nomoto, K; Iwamoto, K; Kishimoto, N

    1997-05-30

    Spectroscopic and photometric evidence indicates that Type Ia supernovae (SNe Ia) are the thermonuclear explosions of accreting white dwarfs. However, the progenitor binary systems and hydrodynamical models for SNe Ia are still controversial. The relatively uniform light curves and spectral evolution of SNe Ia have led to their use as a standard candle for determining cosmological parameters, such as the Hubble constant, the density parameter, and the cosmological constant. Recent progress includes the calibration of the absolute maximum brightness of SNe Ia with the Hubble Space Telescope, the reduction of the dispersion in the Hubble diagram through the use of the relation between the light curve shape and the maximum brightness of SNe Ia, and the discovery of many SNe Ia with high red shifts. PMID:9190677

  5. Type Ia Supernova Progenitors, Cosmology, and Systematics

    NASA Astrophysics Data System (ADS)

    Hayden, Brian

    2013-01-01

    Type Ia supernovae have become fundamental tools for cosmology, but their progenitors, explosion mechanism, and dependence on environment remain key problems to be solved to improve their reliability as cosmological distance estimators. In this talk I will present my research into the nature of SN Ia explosions and their environments, and discuss ongoing efforts to understand systematic errors in SN Ia distance measurements. Using SDSS-II SNe, I developed the 2-stretch fitting method for SN Ia light curves. The 2-stretch method allows the rise and decline portions of the light curve to be fit separately, and as a result I discovered that SN Ia light curves with a normal decline rate show a large variation in rise times. This departure from the single stretch model also results in an average rise time of about 17.5 days, 2 days shorter than previously accepted results. While accurate measurements of the rise time do not significantly improve cosmological results, they do improve the estimate of 56-Ni yield, which is an important constraint in theoretical modeling of SN Ia explosions. Using the 2-stretch fitter, I conducted the first search for shock interactions between the exploding white dwarf and a potential companion star in the single degenerate channel. I found no evidence for shocks in an SDSS-II sample of about 100 SNe, and showed using simulations that this rules out shocks above about 9% of peak SN flux. Comparing to theoretical models of single degenerate progenitors, I rule out red giant companions and main sequence stars above 6 solar masses as common companions to SNe Ia. More recent work has focused on the effect of the SN environment, as multiple studies have shown a correlation between host galaxy mass and SN distances. The source of this mass correlation is unknown, but both metallicity and progenitor age are candidate explanations for the observed correlation. I will present new research that attempts to determine the underlying source of the mass

  6. Turbulence in Type Ia Supernovae Simulations

    NASA Astrophysics Data System (ADS)

    Fisher, Robert

    2012-03-01

    Type Ia supernovae are among the most energetic explosions in the known universe, releasing 10^51 ergs of kinetic energy in their ejecta, with 0.7 solar masses of radioactive Ni-56 synthesized during the explosion. The discovery of the Phillips relation enabled the use of Type Ia supernova (SN Ia) as standardizable cosmological candles, and has ushered in a new era of astronomy leading to the discovery of the acceleration of the universe, leading to the 2011 Nobel Prize in physics. The nature of the Type Ia progenitors, as well as their precise explosion mechanism, remains a subject of active investigation, both observationally as well as theoretically. It is known that the progenitors of Type Ia supernovae are near-Chandrasekhar mass white dwarfs in binary systems, though competing models suggest the companion is either a red giant or main sequence star (the so-called ``single-degenerate channel'') or another white dwarf (the ``double-degenerate channel''). In this talk, I will present recent results of three -dimensional models of the single-degenerate channel of Type Ia supernovae. I will also discuss prospects for modeling the double-degenerate channel of Type Ia supernovae, which have recently enjoyed increased favor from observers and theorists.

  7. Multi-color light curves of type Ia supernovae on thecolor-magnitude diagram: A novel step toward more precise distance andextinction estimates

    SciTech Connect

    Wang, Lifan; Goldhaber, Gerson; Aldering, Greg; Perlmutter, Saul

    2003-01-31

    We show empirically that fits to the color-magnituderelation of Type Ia supernovae after optical maximum can provide accuraterelative extragalactic distances. We report the discovery of an empiricalcolor relation for Type Ia light curves: During much of the first monthpast maximum, the magnitudes of Type Ia supernovae defined at a givenvalue of color index have a very small magnitude dispersion; moreover,during this period the relation between B magnitude and B-V color (or B-Ror B-I color) is strikingly linear, to the accuracy of existingwell-measured data. These linear relations can provide robust distanceestimates, in particular, by using the magnitudes when the supernovareaches a given color. After correction for light curve stretch factor ordecline rate, the dispersion of the magnitudes taken at the intercept ofthe linear color-magnitude relation are found to be around 0^m .08 forthe sub-sample of supernovae with (B_max - V_max) ?= 0^m 0.5, andaround 0^m.11 for the sub-sample with (B_max - V_max) ?= 0^m .2.This small dispersion is consistent with being mostly due toobservational errors. The method presented here and the conventionallight curve fitting methods can be combined to further improvestatistical dispersions of distance estimates. It can be combined withthe magnitude at maximum to deduce dust extinction. Theslopes of thecolor-magnitude relation may also be used to identify intrinsicallydifferent SN Ia systems. The method provides a tool that is fundamentalto using SN Ia to estimate cosmological parameters such as the Hubbleconstant and the mass and dark energy content of theuniverse.

  8. Quantitative Spectroscopy of Distant Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Bronder, T. J.; Hook, I.; Howell, D. A.; Sullivan, M.; Perrett, K.; Conley, A.; Astier, P.; Basa, S.; Carlberg, R. G.; Guy, J.; Pain, R.; Pritchet, C. J.; Neill, James D.

    2007-08-01

    Quantitative analysis of 24 high-z (zmed = 0.81) Type Ia supernovae (SNe Ia) spectra observed at the Gemini Telescopes for the Supernova Legacy Survey (SNLS) is presented. This analysis includes equivalent width measurements of SNe Ia-specific absorption features with methods tailored to the reduced signal-to-noise and host galaxy contamination present in these distant spectra. The results from this analysis are compared to corresponding measurements of a large set of low-z SNe Ia from the literature. This comparison showed no significant difference (less than 2σ) between the spectroscopic features of the distant and nearby SNe; a result that supports the assumption that SNe Ia are not evolving with redshift. Additionally, a new correlation between SiII absorption (observed near peak luminosity) and SNe Ia peak magnitudes is presented.

  9. Could there be a hole in type Ia supernovae?

    SciTech Connect

    Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan

    2004-04-23

    In the favored progenitor scenario, Type Ia supernovae (SNe Ia) arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star; two-dimensional hydrodynamical simulations by Marietta et al. (2001) show that, in the interaction, the companion star carves out a conical hole of opening angle 30-40 degrees in the supernova ejecta. In this paper we use multi-dimensional Monte Carlo radiative transfer calculations to explore the observable consequences of an ejecta-hole asymmetry. We calculate the variation of the spectrum, luminosity, and polarization with viewing angle for the aspherical supernova near maximum light. We find that the supernova looks normal from almost all viewing angles except when one looks almost directly down the hole. In the latter case, one sees into the deeper, hotter layers of ejecta. The supernova is relatively brighter and has a peculiar spectrum characterized by more highly ionized species, weaker absorption features, and lower absorption velocities. The spectrum viewed down the hole is comparable to the class of SN 1991T-like supernovae. We consider how the ejecta-hole asymmetry may explain the current spectropolarimetric observations of SNe Ia, and suggest a few observational signatures of the geometry. Finally, we discuss the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry may fit in as one of several possible sources of diversity.

  10. Constraining Cosmic Evolution of Type Ia Supernovae

    SciTech Connect

    Foley, Ryan J.; Filippenko, Alexei V.; Aguilera, C.; Becker, A.C.; Blondin, S.; Challis, P.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Garnavich, P.M.; Jha, S.; Kirshner, R.P.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miceli, A.; Miknaitis, G.; Pignata, G.; Rest, A.; Riess, A.G.; /UC, Berkeley, Astron. Dept. /Cerro-Tololo InterAmerican Obs. /Washington U., Seattle, Astron. Dept. /Harvard-Smithsonian Ctr. Astrophys. /Chile U., Catolica /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /NOAO, Tucson /Fermilab /Chile U., Santiago /Harvard U., Phys. Dept. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Res. Sch. Astron. Astrophys., Weston Creek /Stockholm U. /Hawaii U. /Illinois U., Urbana, Astron. Dept.

    2008-02-13

    We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 ultraviolet spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows a nearly perfect match of the overall spectral-energy distribution with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host-galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with similar slit widths, which corresponds to different projected distances. After correcting for the galaxy-light contamination, subtle differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be {approx}0.02 mag. The variance in the composite spectra give an estimate of the intrinsic variance in low-redshift maximum-light SN spectra of {approx}3% in the optical and growing toward the ultraviolet. The difference between the maximum-light low and high-redshift spectra constrain SN evolution between our samples to be < 10% in the rest-frame optical.

  11. Photometric selection of Type Ia supernovae in the Supernova Legacy Survey

    NASA Astrophysics Data System (ADS)

    Bazin, G.; Ruhlmann-Kleider, V.; Palanque-Delabrouille, N.; Rich, J.; Aubourg, E.; Astier, P.; Balland, C.; Basa, S.; Carlberg, R. G.; Conley, A.; Fouchez, D.; Guy, J.; Hardin, D.; Hook, I. M.; Howell, D. A.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Sullivan, M.; Fourmanoit, N.; González-Gaitán, S.; Lidman, C.; Perlmutter, S.; Ripoche, P.; Walker, E. S.

    2011-10-01

    We present a sample of 485 photometrically identified Type Ia supernova candidates mined from the first three years of data of the CFHT SuperNova Legacy Survey (SNLS). The images were submitted to a deferred processing independent of the SNLS real-time detection pipeline. Light curves of all transient events were reconstructed in the gM, rM, iM and zM filters and submitted to automated sequential cuts in order to identify possible supernovae. Pure noise and long-term variable events were rejected by light curve shape criteria. Type Ia supernova identification relied on event characteristics fitted to their light curves assuming the events to be normal SNe Ia. The light curve fitter SALT2 was used for this purpose, assigning host galaxy photometric redshifts to the tested events. The selected sample of 485 candidates is one magnitude deeper than that allowed by the SNLS spectroscopic identification. The contamination by supernovae of other types is estimated to be 4%. Testing Hubble diagram residuals with this enlarged sample allows us to measure the Malmquist bias due to spectroscopic selections directly. The result is fully consistent with the precise Monte Carlo based estimate used to correct SN Ia distance moduli in the SNLS 3-year cosmological analyses. This paper demonstrates the feasibility of a photometric selection of high redshift supernovae with known host galaxy redshifts, opening interesting prospects for cosmological analyses from future large photometric SN Ia surveys.

  12. SHOCK BREAKOUT FROM TYPE Ia SUPERNOVA

    SciTech Connect

    Piro, Anthony L.; Chang, Philip; Weinberg, Nevin N. E-mail: pchang@astro.berkeley.ed

    2010-01-01

    The mode of explosive burning in Type Ia supernovae (SNe Ia) remains an outstanding problem. It is generally thought to begin as a subsonic deflagration, but this may transition into a supersonic detonation (the delayed detonation transition, DDT). We argue that this transition leads to a breakout shock, which would provide the first unambiguous evidence that DDTs occur. Its main features are a hard X-ray flash (approx20 keV) lasting approx10{sup -2} s with a total radiated energy of approx10{sup 40} erg, followed by a cooling tail. This creates a distinct feature in the visual light curve, which is separate from the nickel decay. This cooling tail has a maximum absolute visual magnitude of M{sub V} approx -9 to -10 at approx1 day, which depends most sensitively on the white dwarf radius at the time of the DDT. As the thermal diffusion wave moves in, the composition of these surface layers may be imprinted as spectral features, which would help to discern between SN Ia progenitor models. Since this feature should accompany every SNe Ia, future deep surveys (e.g., m = 24) will see it out to a distance of approx80 Mpc, giving a maximum rate of approx60 yr{sup -1}. Archival data sets can also be used to study the early rise dictated by the shock heating (at approx20 days before maximum B-band light). A similar and slightly brighter event may also accompany core bounce during the accretion-induced collapse to a neutron star, but with a lower occurrence rate.

  13. Theoretical cosmic Type Ia supernova rates

    NASA Astrophysics Data System (ADS)

    Valiante, R.; Matteucci, F.; Recchi, S.; Calura, F.

    2009-10-01

    The purpose of this work is the computation of the cosmic Type Ia supernova rates, namely the frequency of Type Ia supernovae per unit time in a unitary volume of the Universe. Our main goal in this work is to predict the Type Ia supernova rates at very high redshifts and to check whether it is possible to select the best delay time distribution model, on the basis of the available observations of Type Ia supernovae. We compute the cosmic Type Ia supernova rates in different scenarios for galaxy formation and predict the expected number of explosions at high redshift ( z⩾2). Moreover, we adopt various progenitor models in order to compute the Type Ia supernova rate in typical elliptical galaxies of initial luminous masses of 1010M⊙,1011M⊙ and 1012M⊙, and compute the total amount of iron produced by Type Ia supernovae in each case. In this analysis we assume that Type Ia supernovae are caused by thermonuclear explosions of C-O white dwarfs in binary systems and we consider the most popular frameworks: the single degenerate and the double degenerate scenarios. The two competing schemes for the galaxy formation, namely the monolithic collapse and the hierarchical clustering, are also taken into account, by considering the histories of star formation increasing and decreasing with redshift, respectively. We calculate the Type Ia supernova rates through an analytical formulation which rests upon the definition of the SN Ia rate following an instantaneous burst of star formation as a function of the time elapsed from the birth of the progenitor system to its explosion as a Type Ia supernova (i.e. the delay time). What emerges from this work is that: (i) we confirm the result of previous papers that it is not easy to select the best delay time distribution scenario from the observational data and this is because the cosmic star formation rate dominates over the distribution function of the delay times; (ii) the monolithic collapse scenario for galaxy formation

  14. Finding Distances to Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-03-01

    Type Ia supernovae are known as standard candles due to their consistency, allowing us to measure distances based on their brightness. But what if these explosions arent quite as consistent as we thought? Due scientific diligence requires careful checks, so a recent study investigates whether the metallicity of a supernovas environment affects the peak luminosity of the explosion.Metallicity Dependence?Type Ia supernovae are incredibly powerful tools for determining distances in our universe. Because these supernovae are formed by white dwarfs that explode when they reach a uniform accreted mass, the supernova peak luminosity is thought to be very consistent. This consistency allows these supernovae to be used as standard candles to measure distances to their host galaxies.But what if that peak luminosity is affected by a factor that we havent taken into account? Theorists have proposed that the luminosities of Type Ia supernovae might depend on the metallicity of their environments with high-metallicity environments suppressing supernova luminosities. If this is true, then we could be systematically mis-measuring cosmological distances using these supernovae.Testing AbundancesSupernova brightnesses vs. the metallicity of their environments. Low-metallicity supernovae (blue shading) and high-metallicity supernovae (red shading) have an average magnitude difference of ~0.14. [Adapted from Moreno-Raya et al. 2016]A team led by Manuel Moreno-Raya, of the Center for Energy, Environment and Technology (CIEMAT) in Spain, has observed 28 Type Ia supernovae in an effort to test for such a metallicity dependence. These supernovae each have independent distance measurements (e.g., from Cepheids or the Tully-Fisher relation).Moreno-Raya and collaborators used spectra from the 4.2-m William Herschel Telescope to estimate oxygen abundances in the region where each of these supernovae exploded. They then used these measurements to determine if metallicity of the local region

  15. Dark Matter Admixed Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Leung, S.-C.; Chu, M.-C.; Lin, L.-M.

    2015-10-01

    We perform two-dimensional hydrodynamic simulations for the thermonuclear explosion of Chandrasekhar-mass white dwarfs with dark matter (DM) cores in Newtonian gravity. We include a 19-isotope nuclear reaction network and make use of the pure turbulent deflagration model as the explosion mechanism in our simulations. Our numerical results show that the general properties of the explosion depend quite sensitively on the mass of the DM core M DM: a larger M DM generally leads to a weaker explosion and a lower mass of synthesized iron-peaked elements. In particular, the total mass of produced can drop from about 0.3 to 0.03 M ⊙ as M DM increases from 0.01 to 0.03 M ⊙. We have also constructed the bolometric light curves obtained from our simulations and found that our results match well with the observational data of sub-luminous Type Ia supernovae.

  16. A common explosion mechanism for type Ia supernovae.

    PubMed

    Mazzali, Paolo A; Röpke, Friedrich K; Benetti, Stefano; Hillebrandt, Wolfgang

    2007-02-01

    Type Ia supernovae, the thermonuclear explosions of white dwarf stars composed of carbon and oxygen, were instrumental as distance indicators in establishing the acceleration of the universe's expansion. However, the physics of the explosion are debated. Here we report a systematic spectral analysis of a large sample of well-observed type Ia supernovae. Mapping the velocity distribution of the main products of nuclear burning, we constrain theoretical scenarios. We find that all supernovae have low-velocity cores of stable iron-group elements. Outside this core, nickel-56 dominates the supernova ejecta. The outer extent of the iron-group material depends on the amount of nickel-56 and coincides with the inner extent of silicon, the principal product of incomplete burning. The outer extent of the bulk of silicon is similar in all supernovae, having an expansion velocity of approximately 11,000 kilometers per second and corresponding to a mass of slightly over one solar mass. This indicates that all the supernovae considered here burned similar masses and suggests that their progenitors had the same mass. Synthetic light-curve parameters and three-dimensional explosion simulations support this interpretation. A single explosion scenario, possibly a delayed detonation, may thus explain most type Ia supernovae. PMID:17289993

  17. Dark Matter Ignition of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Bramante, Joseph

    2015-10-01

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8 σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10 Myr old pulsars at the center of the Milky Way.

  18. Dark Matter Ignition of Type Ia Supernovae.

    PubMed

    Bramante, Joseph

    2015-10-01

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10  Myr old pulsars at the center of the Milky Way. PMID:26551803

  19. PROMPT Ia SUPERNOVAE ARE SIGNIFICANTLY DELAYED

    SciTech Connect

    Raskin, Cody; Scannapieco, Evan; Rhoads, James; Della Valle, Massimo

    2009-12-10

    The time delay between the formation of a population of stars and the onset of type Ia supernovae (SNe Ia) sets important limits on the masses and nature of SN Ia progenitors. Here, we use a new observational technique to measure this time delay by comparing the spatial distributions of SNe Ia to their local environments. Previous work attempted such analyses encompassing the entire host of each SN Ia, yielding inconclusive results. Our approach confines the analysis only to the relevant portions of the hosts, allowing us to show that even so-called prompt SNe Ia that trace star formation on cosmic timescales exhibit a significant delay time of 200-500 million years. This implies that either the majority of Ia companion stars have main-sequence masses less than 3 M {sub sun}, or that most SNe Ia arise from double white dwarf binaries. Our results are also consistent with a SNe Ia rate that traces the white dwarf formation rate, scaled by a fixed efficiency factor.

  20. Supernova Acceleration Probe: Studying Dark Energy with Type Ia Supernovae

    SciTech Connect

    Albert, J.; Aldering, G.; Allam, S.; Althouse, W.; Amanullah, R.; Annis, J.; Astier, P.; Aumeunier, M.; Bailey, S.; Baltay, C.; Barrelet, E.; Basa, S.; Bebek, C.; Bergstom, L.; Bernstein, G.; Bester, M.; Besuner, B.; Bigelow, B.; Blandford, R.; Bohlin, R.; Bonissent, A.; /Caltech /LBL, Berkeley /Fermilab /SLAC /Stockholm U. /Paris, IN2P3 /Marseille, CPPM /Marseille, Lab. Astrophys. /Yale U. /Pennsylvania U. /UC, Berkeley /Michigan U. /Baltimore, Space Telescope Sci. /Indiana U. /Caltech, JPL /Australian Natl. U., Canberra /American Astron. Society /Chicago U. /Cambridge U. /Saclay /Lyon, IPN

    2005-08-08

    The Supernova Acceleration Probe (SNAP) will use Type Ia supernovae (SNe Ia) as distance indicators to measure the effect of dark energy on the expansion history of the Universe. (SNAP's weak-lensing program is described in a separate White Paper.) The experiment exploits supernova distance measurements up to their fundamental systematic limit; strict requirements on the monitoring of each supernova's properties leads to the need for a space-based mission. Results from pre-SNAP experiments, which characterize fundamental SN Ia properties, will be used to optimize the SNAP observing strategy to yield data, which minimize both systematic and statistical uncertainties. With early R&D funding, we have achieved technological readiness and the collaboration is poised to begin construction. Pre-JDEM AO R&D support will further reduce technical and cost risk. Specific details on the SNAP mission can be found in Aldering et al. (2004, 2005). The primary goal of the SNAP supernova program is to provide a dataset which gives tight constraints on parameters which characterize the dark-energy, e.g. w{sub 0} and w{sub a} where w(a) = w{sub 0} + w{sub a}(1-a). SNAP data can also be used to directly test and discriminate among specific dark energy models. We will do so by building the Hubble diagram of high-redshift supernovae, the same methodology used in the original discovery of the acceleration of the expansion of the Universe that established the existence of dark energy (Perlmutter et al. 1998; Garnavich et al. 1998; Riess et al. 1998; Perlmutter et al. 1999). The SNAP SN Ia program focuses on minimizing the systematic floor of the supernova method through the use of characterized supernovae that can be sorted into subsets based on subtle signatures of heterogeneity. Subsets may be defined based on host-galaxy morphology, spectral-feature strength and velocity, early-time behavior, inter alia. Independent cosmological analysis of each subset of ''like'' supernovae can be

  1. The Metrology of Type IA Supernova Lightcurves

    NASA Astrophysics Data System (ADS)

    Rust, Bert W.

    2015-01-01

    The use of Type IA supernovae as standard candles depends crucially on precise measurements of the properties of their light curves. The currently most widely used indicator is Δm15(B), the luminosity drop, measured in magnitudes, in the first 15 days after maximum luminosity. It was selected instead of an estimate of the luminosity decline rate in order to avoid the well known numerical instability in estimating derivatives for measured data. Unfortunately it does not really succeed in this goal, but it is still possible to correlate the widely scattered Δm15 estimates with the absolute magnitude at peak luminosity. The estimation procedure is improved by fitting an accelerated radioactive decay (ARD) model to the measured light curve and making the estimate from that fit. Such fits typically have R2 values greater than 0.99 and produce the expected normally distributed residuals, but still the instability in estimating Δm15 persists. The model has 7 adjustable parameters, one of which, α4, is the acceleration rate for the Ni→Co→Fe nuclear decays. This rate is estimated from the fit to the whole light curve rather than to just a section of it, and α4 is much more tightly correlated with the absolute magnitude at maximum than is Δm15. This paper will compare the two indicators and also suggest two others they may prove useful in the future.

  2. Breaking the colour-reddening degeneracy in Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Sasdelli, Michele; Ishida, E. E. O.; Hillebrandt, W.; Ashall, C.; Mazzali, P. A.; Prentice, S. J.

    2016-07-01

    A new method to study the intrinsic color and luminosity of type Ia supernovae (SNe Ia) is presented. A metric space built using principal component analysis (PCA) on spectral series SNe Ia between -12.5 and +17.5 days from B maximum is used as a set of predictors. This metric space is built to be insensitive to reddening. Hence, it does not predict the part of color excess due to dust-extinction. At the same time, the rich variability of SN Ia spectra is a good predictor of a large fraction of the intrinsic color variability. Such metric space is a good predictor of the epoch when the maximum in the B-V color curve is reached. Multivariate Partial Least Square (PLS) regression predicts the intrinsic B band light-curve and the intrinsic B-V color curve up to a month after maximum. This allows to study the relation between the light curves of SNe Ia and their spectra. The total-to-selective extinction ratio RV in the host-galaxy of SNe Ia is found, on average, to be consistent with typical Milky-Way values. This analysis shows the importance of collecting spectra to study SNe Ia, even with large sample publicly available. Future automated surveys as LSST will provide a large number of light curves. The analysis shows that observing accompaning spectra for a significative number of SNe will be important even in the case of "normal" SNe Ia.

  3. Breaking the color-reddening degeneracy in type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Sasdelli, Michele; Ishida, E. E. O.; Hillebrandt, W.; Ashall, C.; Mazzali, P. A.; Prentice, S.

    2016-04-01

    A new method to study the intrinsic color and luminosity of type Ia supernovae (SNe Ia) is presented. A metric space built using principal component analysis (PCA) on spectral series SNe Ia between -12.5 and +17.5 days from B maximum is used as a set of predictors. This metric space is built to be insensitive to reddening. Hence, it does not predict the part of color excess due to dust-extinction. At the same time, the rich variability of SN Ia spectra is a good predictor of a large fraction of the intrinsic color variability. Such metric space is a good predictor of the epoch when the maximum in the B - V color curve is reached. Multivariate Partial Least Square (PLS) regression predicts the intrinsic B band light-curve and the intrinsic B - V color curve up to a month after maximum. This allows to study the relation between the light curves of SNe Ia and their spectra. The total-to-selective extinction ratio RV in the host-galaxy of SNe Ia is found, on average, to be consistent with typical Milky-Way values. This analysis shows the importance of collecting spectra to study SNe Ia, even with large sample publicly available. Future automated surveys as LSST will provide a large number of light curves. The analysis shows that observing accompaning spectra for a significative number of SNe will be important even in the case of "normal" SNe Ia.

  4. Breaking the colour-reddening degeneracy in Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Sasdelli, Michele; Ishida, E. E. O.; Hillebrandt, W.; Ashall, C.; Mazzali, P. A.; Prentice, S. J.

    2016-07-01

    A new method to study the intrinsic colour and luminosity of Type Ia supernovae (SNe Ia) is presented. A metric space built using principal component analysis on a spectral series for SNe Ia between -12.5 and +17.5 d from the B maximum is used as a set of predictors. This metric space is built to be insensitive to reddening. Hence, it does not predict the part of the colour excess due to dust extinction. At the same time, the rich variability of SN Ia spectra is a good predictor of a large fraction of the intrinsic colour variability. Such a metric space is a good predictor of the epoch when the maximum in the B - V colour curve is reached. Multivariate partial least-squares regression predicts the intrinsic B-band light curve and the intrinsic B - V colour curve up to a month after the maximum. This allows us to study the relation between the light curves of SNe Ia and their spectra. The total-to-selective extinction ratio RV in the host galaxy of SNe Ia is found, on average, to be consistent with typical Milky Way values. This analysis shows the importance of collecting spectra to study SNe Ia, even with a large sample publicly available. Future automated surveys, such as the Large Synoptic Survey Telescope, will provide a large number of light curves. The analysis shows that observing accompanying spectra for a significant number of SNe will be important even for normal SNe Ia.

  5. The distant type Ia supernova rate

    SciTech Connect

    Pain, R.; Fabbro, S.; Sullivan, M.; Ellis, R.S.; Aldering, G.; Astier, P.; Deustua, S.E.; Fruchter, A.S.; Goldhaber, G.; Goobar, A.; Groom, D.E.; Hardin, D.; Hook, I.M.; Howell, D.A.; Irwin, M.J.; Kim, A.G.; Kim, M.Y.; Knop, R.A.; Lee, J.C.; Perlmutter, S.; Ruiz-Lapuente, P.; Schahmaneche, K.; Schaefer, B.; Walton, N.A.

    2002-05-20

    We present a measurement of the rate of distant Type Ia supernovae derived using 4 large subsets of data from the Supernova Cosmology Project. Within this fiducial sample,which surveyed about 12 square degrees, thirty-eight supernovae were detected at redshifts 0.25--0.85. In a spatially flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean red shift z {approx_equal} 0.55 of 1.53 {sub -0.25}{sub -0.31}{sup 0.28}{sup 0.32} x 10{sup -4} h{sup 3} Mpc{sup -3} yr{sup -1} or 0.58{sub -0.09}{sub -0.09}{sup +0.10}{sup +0.10} h{sup 2} SNu(1 SNu = 1 supernova per century per 10{sup 10} L{sub B}sun), where the first uncertainty is statistical and the second includes systematic effects. The dependence of the rate on the assumed cosmological parameters is studied and the redshift dependence of the rate per unit comoving volume is contrasted with local estimates in the context of possible cosmic star formation histories and progenitor models.

  6. The Distant Type Ia Supernova Rate

    DOE R&D Accomplishments Database

    Pain, R.; Fabbro, S.; Sullivan, M.; Ellis, R. S.; Aldering, G.; Astier, P.; Deustua, S. E.; Fruchter, A. S.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hardin, D.; Hook, I. M.; Howell, D. A.; Irwin, M. J.; Kim, A. G.; Kim, M. Y.; Knop, R. A.; Lee, J. C.; Perlmutter, S.; Ruiz-Lapuente, P.; Schahmaneche, K.; Schaefer, B.; Walton, N. A.

    2002-05-28

    We present a measurement of the rate of distant Type Ia supernovae derived using 4 large subsets of data from the Supernova Cosmology Project. Within this fiducial sample, which surveyed about 12 square degrees, thirty-eight supernovae were detected at redshifts 0.25--0.85. In a spatially flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean red shift z {approx_equal} 0.55 of 1.53 {sub -0.25}{sub -0.31}{sup 0.28}{sup 0.32} x 10{sup -4} h{sup 3} Mpc{sup -3} yr{sup -1} or 0.58{sub -0.09}{sub -0.09}{sup +0.10}{sup +0.10} h{sup 2} SNu(1 SNu = 1 supernova per century per 10{sup 10} L{sub B}sun), where the first uncertainty is statistical and the second includes systematic effects. The dependence of the rate on the assumed cosmological parameters is studied and the redshift dependence of the rate per unit comoving volume is contrasted with local estimates in the context of possible cosmic star formation histories and progenitor models.

  7. VELOCITY EVOLUTION AND THE INTRINSIC COLOR OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Foley, Ryan J.; Sanders, Nathan E.; Kirshner, Robert P.

    2011-12-01

    To understand how best to use observations of Type Ia supernovae (SNe Ia) to obtain precise and accurate distances, we investigate the relations between spectra of SNe Ia and their intrinsic colors. Using a sample of 1630 optical spectra of 255 SNe, based primarily on data from the CfA Supernova Program, we examine how the velocity evolution and line strengths of Si II {lambda}6355 and Ca II H and K are related to the B - V color at peak brightness. We find that the maximum-light velocity of Si II {lambda}6355 and Ca II H and K and the maximum-light pseudo-equivalent width of Si II {lambda}6355 are correlated with intrinsic color, with intrinsic color having a linear relation with the Si II {lambda}6355 measurements. Ca II H and K does not have a linear relation with intrinsic color, but lower-velocity SNe tend to be intrinsically bluer. Combining the spectroscopic measurements does not improve intrinsic color inference. The intrinsic color scatter is larger for higher-velocity SNe Ia-even after removing a linear trend with velocity-indicating that lower-velocity SNe Ia are more 'standard crayons'. Employing information derived from SN Ia spectra has the potential to improve the measurements of extragalactic distances and the cosmological properties inferred from them.

  8. The Fast Declining Type Ia Supernova 2003gs, and Evidence for a Significant Dispersion in Near-Infrared Absolute Magnitudes of Fast Decliners at Maximum Light

    NASA Astrophysics Data System (ADS)

    Krisciunas, Kevin; Marion, G. H.; Suntzeff, Nicholas B.; Blanc, Guillaume; Bufano, Filomena; Candia, Pablo; Cartier, Regis; Elias-Rosa, Nancy; Espinoza, Juan; Gonzalez, David; Gonzalez, Luis; Gonzalez, Sergio; Gooding, Samuel D.; Hamuy, Mario; Knox, Ethan A.; Milne, Peter A.; Morrell, Nidia; Phillips, Mark M.; Stritzinger, Maximilian; Thomas-Osip, Joanna

    2009-12-01

    We obtained optical photometry of SN 2003gs on 49 nights, from 2 to 494 days after T(B max). We also obtained near-IR photometry on 21 nights. SN 2003gs was the first fast declining Type Ia SN that has been well observed since SN 1999by. While it was subluminous in optical bands compared to more slowly declining Type Ia SNe, it was not subluminous at maximum light in the near-IR bands. There appears to be a bimodal distribution in the near-IR absolute magnitudes of Type Ia SNe at maximum light. Those that peak in the near-IR after T(B max) are subluminous in the all bands. Those that peak in the near-IR prior to T(B max), such as SN 2003gs, have effectively the same near-IR absolute magnitudes at maximum light regardless of the decline rate Δm 15(B). Near-IR spectral evidence suggests that opacities in the outer layers of SN 2003gs are reduced much earlier than for normal Type Ia SNe. That may allow γ rays that power the luminosity to escape more rapidly and accelerate the decline rate. This conclusion is consistent with the photometric behavior of SN 2003gs in the IR, which indicates a faster than normal decline from approximately normal peak brightness. Based in part on observations taken at the Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation. The near-IR photometry from La Silla and Paranal was obtained by the European Supernova Collaboration (ESC).

  9. THE ULTRAVIOLET BRIGHTEST TYPE Ia SUPERNOVA 2011de

    SciTech Connect

    Brown, Peter J.

    2014-11-20

    We present and discuss the ultraviolet (UV)/optical photometric light curves and absolute magnitudes of the Type Ia supernova (SN Ia) 2011de from the Swift Ultraviolet/Optical Telescope. We find it to be the UV brightest SN Ia yet observed—more than a factor of 10 brighter than normal SNe Ia in the mid-ultraviolet. We find that the UV/optical brightness and broad light curve evolution can be modeled with additional flux from the shock of the ejecta hitting a relatively large red giant companion separated by 6 × 10{sup 13} cm. However, the post-maximum behavior of other UV-bright SNe Ia can also be modeled in a similar manner, including objects with UV spectroscopy or pre-maximum photometry which is inconsistent with this model. This suggests that similar UV luminosities can be intrinsic or caused by other forms of shock interaction. The high velocities reported for SN 2011de make it distinct from the UV-bright ''super-Chandrasekhar'' SNe Ia and the NUV-blue group of normal SNe Ia. SN 2011de is an extreme example of the UV variations in SNe Ia.

  10. Type IA supernovae: Their progenitors and use as cosmological probes

    NASA Astrophysics Data System (ADS)

    Patel, Brandon

    Type Ia supernovae (SNe Ia) are important cosmological probes, but we are uncertain how they explode. There are two progenitor channels for SNe Ia: single and double degenerate white dwarf (WD) systems. In either model, we expect the system to be detectable as a Supersoft X-ray Source (SSS) for a significant amount of time before the explosion. By studying these SSSs, we hope to improve our understanding of SNe Ia. In Chapter 2, we analyze an interesting source (r1-25) in M31. We found that the source exhibited spectral changes to harder X-ray states. r1-25 is the first source of its kind, and we require unique physical models to fit its behavior. We find that existing WD models are inconsistent with the spectra of the source. We explore new black hole and neutron star models, and find that they can model the unusual behavior of r1-25. In Chapter 3, we study three gravitationally lensed SNe from the Cluster Lensing And Supernova survey with Hubble (CLASH). Based on photometric classification, we found that two SNe (SN CLO12Car and CLN12Did) are likely to be SNe Ia, while the classification of the third is inconclusive. Using multi-color light-curve fits to determine a standardized SN Ia luminosity distance, we infer that SN CLO12Car was ˜ 1.0 +/- 0.2 mag brighter than field SNe Ia at a similar redshift and ascribe this to gravitational lens magnification. Similarly, SN CLN12Did is ˜ 0.2 +/- 0.2 mag brighter than field SNe Ia. From independent CLASH strong+weak lensing maps of the clusters , we derived similar magnifications for the two SNe Ia. The two SNe Ia provide a new test of the cluster lens model predictions: we find that the magnifications based on the SN Ia brightness and those predicted by the lens maps are consistent. Finally, in Chapter 4 we discuss a new light curve fitter for SNe Ia, which we call Multicolor Light Curve Shapes 3 (MLCS3). The project has not been completed, but we discuss some of the features, and the expected improvements from MLCS3

  11. Photometric Selection of High-Redshift Type Ia Supernova Candidates

    NASA Astrophysics Data System (ADS)

    Sullivan, M.; Howell, D. A.; Perrett, K.; Nugent, P. E.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Aldering, G.; Baumont, S.; Bronder, J.; Filiol, M.; Knop, R. A.; Perlmutter, S.; Tao, C.

    2006-02-01

    We present a method for selecting high-redshift Type Ia supernovae (SNe Ia) located via rolling SN searches. The technique, using both color and magnitude information of events from only two to three epochs of multiband real-time photometry, is able to discriminate between SNe Ia and core-collapse SNe. Furthermore, for SNe Ia the method accurately predicts the redshift, phase, and light-curve parameterization of these events based only on pre-maximum-light data. We demonstrate the effectiveness of the technique on a simulated survey of SNe Ia and core-collapse SNe, where the selection method effectively rejects most core-collapse SNe while retaining SNe Ia. We also apply the selection code to real-time data acquired as part of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). During the period 2004 May to 2005 January in the SNLS, 440 SN candidates were discovered, of which 70 were confirmed spectroscopically as SNe Ia and 15 as core-collapse events. For this test data set, the selection technique correctly identifies 100% of the identified SNe II as non-SNe Ia with only a 1%-2% false rejection rate. The predicted parameterization of the SNe Ia has a precision of Δz/(1+zspec)<0.09 in redshift and +/-2-3 rest-frame days in phase, providing invaluable information for planning spectroscopic follow-up observations. We also investigate any bias introduced by this selection method on the ability of surveys such as SNLS to measure cosmological parameters (e.g., w and ΩM) and find any effect to be negligible.

  12. The progenitors of supernovae Type Ia

    NASA Astrophysics Data System (ADS)

    Toonen, Silvia

    2014-09-01

    Despite the significance of Type Ia supernovae (SNeIa) in many fields in astrophysics, SNeIa lack a theoretical explanation. SNeIa are generally thought to be thermonuclear explosions of carbon/oxygen (CO) white dwarfs (WDs). The canonical scenarios involve white dwarfs reaching the Chandrasekhar mass, either by accretion from a non-degenerate companion (single-degenerate channel, SD) or by a merger of two CO WDs (double-degenerate channel, DD). The study of SNeIa progenitors is a very active field of research for binary population synthesis (BPS) studies. The strength of the BPS approach is to study the effect of uncertainties in binary evolution on the macroscopic properties of a binary population, in order to constrain binary evolutionary processes. I will discuss the expected SNeIa rate from the BPS approach and the uncertainties in their progenitor evolution, and compare with current observations. I will also discuss the results of the POPCORN project in which four BPS codes were compared to better understand the differences in the predicted SNeIa rate of the SD channel. The goal of this project is to investigate whether differences in the simulated populations are due to numerical effects or whether they can be explained by differences in the input physics. I will show which assumptions in BPS codes affect the results most and hence should be studied in more detail.

  13. Precision Constraints from Computational Cosmology and Type Ia Supernova Simulations

    NASA Astrophysics Data System (ADS)

    Bernstein, Joseph P.; Kuhlmann, S. E.; Norris, B.; Biswas, R.

    2011-01-01

    The evidence for dark energy represents one of the greatest mysteries of modern science. The research undertaken probes the implications of dark energy via analysis of large scale structure and detonation-based Type Ia supernova light curve simulations. It is presently an exciting time to be involved in cosmology because planned astronomical surveys will effectively result in dark sector probes becoming systematics-limited, making numerical simulations crucial to the formulation of precision constraints. This work aims to assist in reaching the community goal of 1% constraints on the dark energy equation of state parameter. Reaching this goal will require 1) hydrodynamic+N-body simulations with a minimum of a 1 Gpc box size, 20483 hydrodynamic cells, and 1011 dark matter particles, which push the limits of existing codes, and 2) a better understanding of the explosion mechanism(s) for Type Ia supernovae, together with larger, high-quality data sets from present and upcoming supernova surveys. Initial results are discussed from two projects. The first is computational cosmology studies aimed at enabling the large simulations discussed above. The second is radiative transfer calculations drawn from Type Ia supernova explosion simulations aimed at bridging the gap between simulated light curves and those observed from, e.g., the Sloan Digital Sky Survey II and, eventually, the Dark Energy Survey.

  14. Genetic algorithms and supernovae type Ia analysis

    SciTech Connect

    Bogdanos, Charalampos; Nesseris, Savvas E-mail: nesseris@nbi.dk

    2009-05-15

    We introduce genetic algorithms as a means to analyze supernovae type Ia data and extract model-independent constraints on the evolution of the Dark Energy equation of state w(z) {identical_to} P{sub DE}/{rho}{sub DE}. Specifically, we will give a brief introduction to the genetic algorithms along with some simple examples to illustrate their advantages and finally we will apply them to the supernovae type Ia data. We find that genetic algorithms can lead to results in line with already established parametric and non-parametric reconstruction methods and could be used as a complementary way of treating SNIa data. As a non-parametric method, genetic algorithms provide a model-independent way to analyze data and can minimize bias due to premature choice of a dark energy model.

  15. Radiation Transport in Type IA Supernovae

    SciTech Connect

    Eastman, R

    1999-11-16

    It has been said more than once that the critical link between explosion models and observations is the ability to accurately simulate cooling and radiation transport in the expanding ejecta of Type Ia supernovae. It is perhaps frustrating to some of the theorists who study explosion mechanisms, and to some of the observers too, that more definitive conclusions have not been reached about the agreement, or lack thereof, between various Type Ia supernova models and the data. Although claims of superlative accuracy in transport simulations are sometimes made, I will argue here that there are outstanding issues of critical importance and in need of addressing before radiation transport calculations are accurate enough to discriminate between subtly different explosion models.

  16. The Effect of Host Galaxies on Type Ia Supernovae in the SDSS-II Supernova Survey

    SciTech Connect

    Lampeitl, Hubert; Smith, Mathew; Nichol, Robert C.; Bassett, Bruce; Cinabro, David; Dilday, Benjamin; Foley, Ryan J.; Frieman, Joshua A.; Garnavich, Peter M.; Goobar, Ariel; Im, Myungshin; /Seoul Natl. U. /Rutgers U., Piscataway

    2010-05-01

    We present an analysis of the host galaxy dependencies of Type Ia Supernovae (SNe Ia) from the full three year sample of the SDSS-II Supernova Survey. We re-discover, to high significance, the strong correlation between host galaxy type and the width of the observed SN light curve, i.e., fainter, quickly declining SNe Ia favor passive host galaxies, while brighter, slowly declining Ia's favor star-forming galaxies. We also find evidence (at between 2 to 3{sigma}) that SNe Ia are {approx_equal} 0.1 magnitudes brighter in passive host galaxies, than in star-forming hosts, after the SN Ia light curves have been standardized using the light curve shape and color variations: This difference in brightness is present in both the SALT2 and MCLS2k2 light curve fitting methodologies. We see evidence for differences in the SN Ia color relationship between passive and star-forming host galaxies, e.g., for the MLCS2k2 technique, we see that SNe Ia in passive hosts favor a dust law of R{sub V} {approx_equal} 1, while SNe Ia in star-forming hosts require R{sub V} {approx} 2. The significance of these trends depends on the range of SN colors considered. We demonstrate that these effects can be parameterized using the stellar mass of the host galaxy (with a confidence of > 4{sigma}) and including this extra parameter provides a better statistical fit to our data. Our results suggest that future cosmological analyses of SN Ia samples should include host galaxy information.

  17. Type Ia supernovae yielding distances with 3-4% precision

    SciTech Connect

    Kelly, Patrick L.; Filippenko, Alexei V.; Burke, David L.; Hicken, Malcolm; Ganeshalingam, Mohan; Zheng, Weikang

    2015-01-26

    The luminosities of Type Ia supernovae (SN), the thermonuclear explosions of white dwarf stars, vary systematically with their intrinsic color and light-curve decline rate. These relationships have been used to calibrate their luminosities to within ~0.14–0.20 mag from broadband optical light curves, yielding individual distances accurate to ~7–10%. Here we identify a subset of SN Ia that erupt in environments having high ultraviolet surface brightness and star-formation surface density. When we apply a steep model extinction law, these SN can be calibrated to within ~0.065–0.075 mag, corresponding to ~3–4% in distance — the best yet with SN Ia by a substantial margin. The small scatter suggests that variations in only one or two progenitor properties account for their light-curve-width/color/luminosity relation.

  18. On the environments of Type Ia supernovae within host galaxies

    NASA Astrophysics Data System (ADS)

    Anderson, J. P.; James, P. A.; Förster, F.; González-Gaitán, S.; Habergham, S. M.; Hamuy, M.; Lyman, J. D.

    2015-03-01

    We present constraints on Type Ia supernovae (SNe Ia) progenitors through an analysis of the environments found at the explosion sites of 102 events within star-forming host galaxies. Hα and Galaxy Evolution Explorer near-ultraviolet (UV) images are used to trace on-going and recent star formation (SF), while broad-band B, R, J, K imaging is also analysed. Using pixel statistics we find that SNe Ia show the lowest degree of association with Hα emission of all supernova (SN) types. It is also found that they do not trace near-UV emission. As the latter traces SF on time-scales less than 100 Myr, this rules out any extreme `prompt' delay times as the dominant progenitor channel of SNe Ia. SNe Ia best trace the B-band light distribution of their host galaxies. This implies that the population within star-forming galaxies is dominated by relatively young progenitors. Splitting SNe by their (B - V) colours at maximum light, `redder' events show a higher degree of association with H II regions and are found more centrally within hosts. We discuss possible explanations of this result in terms of line-of-sight extinction and progenitor effects. No evidence for correlations between SN stretch and environment properties is observed.

  19. Type IA Supernova Cosmology: Past and Future

    NASA Astrophysics Data System (ADS)

    Goobar, Ariel

    2015-01-01

    Type Ia supernovae (SNe Ia) have been used with remarkable success to map the expansion history of the Universe. These measurements dramatically changed our description of nature as they revealed cosmic acceleration, indicating the presence of new physics, dark energy, counteracting the effect of gravity at the largest scales. Understanding the source of the acceleration ranks among the most pressing undertakings in fundamental physics. Current and future surveys are challenged to accurately measure the equation state of dark energy, the parameter used to explore its nature. Distances measurements using SNe Ia remain among the most powerful techniques in observational cosmologists. The recent history of the field is reviewed, as well as current limitations and opportunities for the future.

  20. The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-time Observations, First-light Time, Distance to NGC 4666, and Progenitor Constraints

    NASA Astrophysics Data System (ADS)

    Shappee, B. J.; Piro, A. L.; Holoien, T. W.-S.; Prieto, J. L.; Contreras, C.; Itagaki, K.; Burns, C. R.; Kochanek, C. S.; Stanek, K. Z.; Alper, E.; Basu, U.; Beacom, J. F.; Bersier, D.; Brimacombe, J.; Conseil, E.; Danilet, A. B.; Dong, Subo; Falco, E.; Grupe, D.; Hsiao, E. Y.; Kiyota, S.; Morrell, N.; Nicolas, J.; Phillips, M. M.; Pojmanski, G.; Simonian, G.; Stritzinger, M.; Szczygieł, D. M.; Taddia, F.; Thompson, T. A.; Thorstensen, J.; Wagner, M. R.; Woźniak, P. R.

    2016-08-01

    On 2014 December 9.61, the All-sky Automated Survey for SuperNovae (ASAS-SN or “Assassin”) discovered ASASSN-14lp just ˜2 days after first light using a global array of 14 cm diameter telescopes. ASASSN-14lp went on to become a bright supernova (V = 11.94 mag), second only to SN 2014J for the year. We present prediscovery photometry (with a detection less than a day after first light) and ultraviolet through near-infrared photometric and spectroscopic data covering the rise and fall of ASASSN-14lp for more than 100 days. We find that ASASSN-14lp had a broad light curve ({{Δ }}{m}15(B)=0.80+/- 0.05), a B-band maximum at 2457015.82 ± 0.03, a rise time of {16.94}-0.10+0.11 days, and moderate host-galaxy extinction (E{(B-V)}{host}=0.33+/- 0.06). Using ASASSN-14lp, we derive a distance modulus for NGC 4666 of μ =30.8+/- 0.2, corresponding to a distance of 14.7 ± 1.5 Mpc. However, adding ASASSN-14lp to the calibrating sample of Type Ia supernovae still requires an independent distance to the host galaxy. Finally, using our early-time photometric and spectroscopic observations, we rule out red giant secondaries and, assuming a favorable viewing angle and explosion time, any nondegenerate companion larger than 0.34 {R}ȯ .

  1. The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-time Observations, First-light Time, Distance to NGC 4666, and Progenitor Constraints

    NASA Astrophysics Data System (ADS)

    Shappee, B. J.; Piro, A. L.; Holoien, T. W.-S.; Prieto, J. L.; Contreras, C.; Itagaki, K.; Burns, C. R.; Kochanek, C. S.; Stanek, K. Z.; Alper, E.; Basu, U.; Beacom, J. F.; Bersier, D.; Brimacombe, J.; Conseil, E.; Danilet, A. B.; Dong, Subo; Falco, E.; Grupe, D.; Hsiao, E. Y.; Kiyota, S.; Morrell, N.; Nicolas, J.; Phillips, M. M.; Pojmanski, G.; Simonian, G.; Stritzinger, M.; Szczygieł, D. M.; Taddia, F.; Thompson, T. A.; Thorstensen, J.; Wagner, M. R.; Woźniak, P. R.

    2016-08-01

    On 2014 December 9.61, the All-sky Automated Survey for SuperNovae (ASAS-SN or “Assassin”) discovered ASASSN-14lp just ∼2 days after first light using a global array of 14 cm diameter telescopes. ASASSN-14lp went on to become a bright supernova (V = 11.94 mag), second only to SN 2014J for the year. We present prediscovery photometry (with a detection less than a day after first light) and ultraviolet through near-infrared photometric and spectroscopic data covering the rise and fall of ASASSN-14lp for more than 100 days. We find that ASASSN-14lp had a broad light curve ({{Δ }}{m}15(B)=0.80+/- 0.05), a B-band maximum at 2457015.82 ± 0.03, a rise time of {16.94}-0.10+0.11 days, and moderate host-galaxy extinction (E{(B-V)}{host}=0.33+/- 0.06). Using ASASSN-14lp, we derive a distance modulus for NGC 4666 of μ =30.8+/- 0.2, corresponding to a distance of 14.7 ± 1.5 Mpc. However, adding ASASSN-14lp to the calibrating sample of Type Ia supernovae still requires an independent distance to the host galaxy. Finally, using our early-time photometric and spectroscopic observations, we rule out red giant secondaries and, assuming a favorable viewing angle and explosion time, any nondegenerate companion larger than 0.34 {R}ȯ .

  2. Type Ia supernovae: explosions and progenitors

    NASA Astrophysics Data System (ADS)

    Kerzendorf, Wolfgang Eitel

    2011-08-01

    Supernovae are the brightest explosions in the universe. Supernovae in our Galaxy, rare and happening only every few centuries, have probably been observed since the beginnings of mankind. At first they were interpreted as religious omens but in the last half millennium they have increasingly been used to study the cosmos and our place in it. Tycho Brahe deduced from his observations of the famous supernova in 1572, that the stars, in contrast to the widely believe Aristotelian doctrine, were not immutable. More than 400 years after Tycho made his paradigm changing discovery using SN 1572, and some 60 years after supernovae had been identified as distant dying stars, two teams changed the view of the world again using supernovae. The found that the Universe was accelerating in its expansion, a conclusion that could most easily be explained if more than 70% of the Universe was some previously un-identified form of matter now often referred to as `Dark Energy'. Beyond their prominent role as tools to gauge our place in the Universe, supernovae themselves have been studied well over the past 75 years. We now know that there are two main physical causes of these cataclysmic events. One of these channels is the collapse of the core of a massive star. The observationally motivated classes Type II, Type Ib and Type Ic have been attributed to these events. This thesis, however is dedicated to the second group of supernovae, the thermonuclear explosions of degenerate carbon and oxygen rich material and lacking hydrogen - called Type Ia supernovae (SNe Ia). White dwarf stars are formed at the end of a typical star's life when nuclear burning ceases in the core, the outer envelope is ejected, with the degenerate core typically cooling for eternity. Theory predicts that such stars will self ignite when close to 1.38 Msun (called the Chandrasekhar Mass). Most stars however leave white dwarfs with 0.6 Msun, and no star leaves a remnant as heavy as 1.38 M! sun, which suggests

  3. K-corrections and spectral templates of Type Ia supernovae

    SciTech Connect

    Nugent, Peter E; Hsiao, E.Y.; Conley, A.; Howell, D.A.; Sullivan, M.; Pritchet, C.J.; Carlberg, R.G.; Nugent, P.E.; Phillips, M.M.

    2007-03-20

    With the advent of large dedicated Type Ia supernova (SN Ia) surveys, K-corrections of SNe Ia and their uncertainties have become especially important in the determination of cosmological parameters. While K-corrections are largely driven by SN Ia broadband colors, it is shown here that the diversity in spectral features of SNe Ia can also be important. For an individual observation, the statistical errors from the inhomogeneity in spectral features range from 0.01 (where the observed and rest-frame filters are aligned) to 0.04 (where the observed and rest-frame filters are misaligned). To minimize the systematic errors caused by an assumed SN Ia spectral energy distribution (SED), we outline a prescription for deriving a mean spectral template time series that incorporates a large and heterogeneous sample of observed spectra. We then remove the effects of broadband colors and measure the remaining uncertainties in the K-corrections associated with the diversity in spectral features. Finally, we present a template spectroscopic sequence near maximum light for further improvement on the K-correction estimate. A library of ~;;600 observed spectra of ~;;100 SNe Ia from heterogeneous sources is used for the analysis.

  4. FIXING THE U-BAND PHOTOMETRY OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Krisciunas, Kevin; Bastola, Deepak; Suntzeff, Nicholas B.; Espinoza, Juan; Gonzalez, David; Gonzalez, Luis; Gonzalez, Sergio; Hsiao, Eric Y.; Morrell, Nidia; Phillips, Mark M.; Hamuy, Mario E-mail: suntzeff@physics.tamu.edu E-mail: hsiao@lco.cl E-mail: mmp@lco.cl

    2013-01-01

    We present previously unpublished photometry of supernovae 2003gs and 2003hv. Using spectroscopically derived corrections to the U-band photometry, we reconcile U-band light curves made from imagery with the Cerro Tololo 0.9 m, 1.3 m, and Las Campanas 1 m telescopes. Previously, such light curves showed a 0.4 mag spread at one month after maximum light. This gives us hope that a set of corrected ultraviolet light curves of nearby objects can contribute to the full utilization of rest-frame U-band data of supernovae at redshift {approx}0.3-0.8. As pointed out recently by Kessler et al. in the context of the Sloan Digital Sky Survey supernova search, if we take the published U-band photometry of nearby Type Ia supernovae at face value, there is a 0.12 mag U-band anomaly in the distance moduli of higher redshift objects. This anomaly led the Sloan survey to eliminate from their analyses all photometry obtained in the rest-frame U-band. The Supernova Legacy Survey eliminated observer frame U-band photometry, which is to say nearby objects observed in the U-band, but they used photometry of high-redshift objects no matter in which band the photons were emitted.

  5. The Impact of Hosts on Type Ia Supernovae Cosmology

    NASA Astrophysics Data System (ADS)

    Ashraf Uddin, Syed; Mould, Jeremy; Lidman, Chris

    2015-08-01

    We compile a sample of 595 spectroscopically confirmed Type Ia Supernovae (SNe Ia), with consistently derived host galaxy properties such as stellar mass, specific star-formation rate and projected distances of SNe Ia from host centers, from the CSP, CfA, SDSS, and SNLS surveys. Our results confirm previous findings that SNe Ia are on average significantly brighter in more massive and low-specific star-formation rate hosts after correcting for light-curve parameters. We study, for the first time, the variation of SNe Ia - host correlations with redshift and detect no evolution. We find new evidence that the slope of the stretch-luminosity relation is steeper in SNe Ia that are exploding farther out from host centers and confirm previous finding that the slope of the color-luminosity relation is shallower in massive hosts. We split the sample into pairs of subsets that are based on the properties of the hosts, and fit cosmological models to each subset. We do not find any dependence of the cosmology between the pairs of subsets used. Among different subsets, we find SNe Ia in high-specific star-formation rate have the least intrinsic scatter in luminosity, which supports theoretical prediction. Host stellar mass is the dominant host property for the observed correlations. Adding host mass as the third correction factor in distance measurement, we find no significant change in the measurements of cosmological parameters. Furthermore, we show that the best-fit cosmology is not biased between the SNe Ia samples where redshifts come from hosts and SNe Ia respectively - an important result for future SNe Ia cosmology surveys, such as the Dark Energy Survey.

  6. Spectrum synthesis of the Type Ia supernovae SN 1992A and SN 1981B

    NASA Technical Reports Server (NTRS)

    Nugent, Peter; Baron, E.; Hauschildt, Peter H.; Branch, David

    1995-01-01

    We present non-local thermodynamic equilibrium (non-LTE) synthetic spectra for the Type Ia supernovae SN 1992A and SN 1981B, near maximum light. At this epoch both supernovae were observed from the UV through the optical. This wide spectral coverage is essential for determining the density structure of a SN Ia. Our fits are in good agreement with observation and provide some insight as to the differences between these supernovae. We also discuss the application of the expanding photosphere method to SNe Ia which gives a distance that is independent of those based on the decay of Ni-56 and Cepheid variable stars.

  7. THE CARNEGIE SUPERNOVA PROJECT: FIRST PHOTOMETRY DATA RELEASE OF LOW-REDSHIFT TYPE Ia SUPERNOVAE

    SciTech Connect

    Contreras, Carlos; Phillips, M. M.; Folatelli, Gaston; Stritzinger, Maximilian; Boldt, Luis; Gonzalez, Sergio; Krzeminski, Wojtek; Morrell, Nidia; Roth, Miguel; Salgado, Francisco; Hamuy, Mario; Maureira, MarIa Jose; Suntzeff, Nicholas B.; Persson, S. E.; Burns, Christopher R.; Freedman, W. L.; Madore, Barry F.; Murphy, David; Wyatt, Pamela

    2010-02-15

    The Carnegie Supernova Project (CSP) is a five-year survey being carried out at the Las Campanas Observatory to obtain high-quality light curves of {approx}100 low-redshift Type Ia supernovae (SNe Ia) in a well-defined photometric system. Here we present the first release of photometric data that contains the optical light curves of 35 SNe Ia, and near-infrared light curves for a subset of 25 events. The data comprise 5559 optical (ugriBV) and 1043 near-infrared (Y JHK{sub s} ) data points in the natural system of the Swope telescope. Twenty-eight SNe have pre-maximum data, and for 15 of these, the observations begin at least 5 days before B maximum. This is one of the most accurate data sets of low-redshift SNe Ia published to date. When completed, the CSP data set will constitute a fundamental reference for precise determinations of cosmological parameters, and serve as a rich resource for comparison with models of SNe Ia.

  8. The Nature of Dark Energy from Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Hook, Isobel

    2007-02-01

    Type Ia supernovae (SNe Ia) currently provide the most direct evidence for an accelerating Universe and for the existence of an unknown "dark energy". The 5-year Supernova Legacy Survey (SNLS) is generating a definitive dataset with well-sampled g'r'i'z' light curves and spectroscopic confirmation, which together allow precise measurement of the cosmological parameters. We are now entering the final 18 months of this highly successful survey. With the full, final sample we expect to determine the cosmological equation of state parameter "w" to a statistical precision of +/-0.05 or better, testing theories for the origin of the universal acceleration. The amount of spectroscopic follow-up performed is central to the success of the survey. Approximately 500 SNe Ia will be spectroscopically confirmed in a coherent program involving Gemini, VLT and Keck. Nod-and-shuffle observations at Gemini play a pivotal role. The goal for Gemini this semester is to obtain types and redshifts for 30 SN Ia candidates with redshifts 0.6-0.9, contributing to a dataset superior to any existing - or planned - sample. This is a continuing QR (quick response) proposal for GMOS-N.

  9. Near-Infrared Spectra of Type Ia Supernovae

    NASA Technical Reports Server (NTRS)

    Marion, G. H.; Hoeflich, P.; Vacca, W. D.; Wheeler, J. C.

    2003-01-01

    We report near-infrared (NIR) spectroscopic observations of 12 'branch-normal' Type Ia supernovae (SNe Ia) that cover the wavelength region from 0.8 to 2.5 microns. Our sample more than doubles the number of SNe Ia with published NIR spectra within 3 weeks of maximum light. The epochs of observation range from 13 days before maximum light to 18 days after maximum light. A detailed model for a Type Ia supernovae is used to identify spectral features. The Doppler shifts of lines are measured to obtain the velocity and thus the radial distribution of elements. The NIR is an extremely useful tool to probe the chemical structure in the layers of SNe Ia ejecta. This wavelength region is optimal for examining certain products of the SNe Ia explosion that may be blended or obscured in other spectral regions. We identify spectral features from Mg II, Ca II, Si II, Fe II, Co II, Ni II, and possibly Mn II. We find no indications for hydrogen, helium, or carbon in the spectra. The spectral features reveal important clues about the physical characteristics of SNe Ia. We use the features to derive upper limits for the amount of unburned matter, to identify the transition regions from explosive carbon to oxygen burning and from partial to complete silicon burning, and to estimate the level of mixing during and after the explosion. Elements synthesized in the outer layers during the explosion appear to remain in distinct layers. That provides strong evidence for the presence of a detonation phase during the explosion as it occurs in delayed detonation or merger models. Mg II velocities are found to exceed 11,000 - 15,000 km/s, depending on the individual SNe Ia. That result suggests that burning during the explosion reaches the outermost layers of the progenitor and limits the amount of unburned material to less than 10% of the mass of the progenitor. Small residuals of unburned material are predicted by delayed detonation models but are inconsistent with pure deflagration or

  10. A New Empirical Model for Type Ia Supernovae Using Spectrophotometry from the Nearby Supernova Factory

    NASA Astrophysics Data System (ADS)

    Saunders, Clare; Nearby Supernova Factory

    2016-01-01

    Type Ia supernovae are currently limited in their use for cosmology by dispersion in standardized magnitudes. A large part of this dispersion is due to the fact that the current lightcurve fitters do not describe the full range of Type Ia supernova diversity. I will present an empirical model of Type Ia supernovae that captures a wider range of supernova behavior and can improve magnitude standardization. This model is constructed using over 2000 spectrophotometric observations of Type Ia supernovae from the Nearby Supernova Factory. The true spectral time series for each supernova is modeled using Gaussian Processes. The supernova model predictions are used to calculate the principal components of the full set of supernova spectral time series. K-fold cross-validation is used to determine how many components correlate to absolute magnitude. Future work will test this method on independent photometric data sets.

  11. White Dwarf Convection Preceding Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Zingale, Michael; Almgren, A. S.; Bell, J. B.; Malone, C. M.; Nonaka, A.; Woosley, S. E.

    2010-01-01

    In the single degenerate scenario for Type Ia supernovae, a Chandrasekhar mass white dwarf `simmers' for centuries preceding the ultimate explosion. During this period, reactions near the center drive convection throughout most of the interior of the white dwarf. The details of this convective flow determine how the first flames in the white dwarf ignite. Simulating this phase is difficult because the flows are highly subsonic. Using the low Mach number hydrodynamics code, MAESTRO, we present 3-d, full star models of the final hours of this convective phase, up to the point of ignition of a Type Ia supernova. We discuss the details of the convective velocity field and the locations of the initial hot spots. Finally, we show some preliminary results with rotation. Support for this work came from the DOE/Office of Nuclear Physics, grant No. DE-FG02-06ER41448 (Stony Brook), the SciDAC Program of the DOE Office of Mathematics, Information, and Computational Sciences under the DOE under contract No. DE-AC02-05CH11231 (LBNL), and the DOE SciDAC program, under grant No. DE-FC02-06ER41438 (UCSC). We made use of the jaguar machine via a DOE INCITE allocation at the Oak Ridge Leadership Computational Facility.

  12. The Nuclear Physics of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Brown, Edward

    2016-03-01

    Type Ia supernovae (SNe Ia) are the thermonuclear incineration of white dwarfs, which are the evolutionary terminus of low-mass stars; these supernovae are a primary source of iron in the universe and the premier distance indicator for cosmological studies. Current and future observational surveys are uncovering tantalizing clues about the as-yet-unknown progenitors of these explosions. In this talk, I shall review the nuclear physics of the explosion, with a particular emphasis on the role of weak interactions. Electron captures during the pre-explosive ``simmering'' and the explosion make the nucleosynthetic yields more neutron-rich. This provides in principle a way to constrain the nature of the progenitor from observations. I shall also highlight recent experimental constraints on electron-capture rates and prospects for further experimental studies, such as at the Facility for Rare Isotope Beams. Support by the National Science Foundation under Grant No. PHY-1430152 (JINA Center for the Evolution of the Elements) is gratefully acknowledged.

  13. Imaging the Distribution of Iron in a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Fesen, Robert

    2009-07-01

    We know Type Ia supernovae are thermonuclear explosions of CO white dwarfs, but we don't know the specifics of how the nuclear burning proceeds from the core outward to the surface once it starts. Thermonuclear instability in a WD core is thought to start off as a subsonic, turbulent deflagration wave or "burning" wave but then may, at some point, transition into a supernova blast or detonation wave. In such a "delayed detonation" model, differences between normal and subluminous Type Ia SNe reflect differences in the amount of burning that has occurred in the pre-detonation phase. More burning helps to pre-expand the WD before passage of the detontation wave which then lowers the density of the outer layers and, in turn, results in a different element production and internal structure.Directly imaging the 2D chemical distribution of ejecta from a Type Ia SN is actually possible in the case of the subluminous Type Ia SN 1885 which occurred on the near-side of M31's central bulge. The entire 123 year old remnant -- core to outer edge -- is visible via strong near-UV, Ca and Fe line absorptions, and remarkably, is still in near free expansion. This means that elemental stratification seen today is likely to accurately reflect the explosive nucleosynthesis physics.We propose ACS WFC images of SN 1885 to take advantage of this extraordinary situation: Having a young, nearby Type Ia SN remnant visible in silhouette against a galaxy-size light table. The proposed observations will reveal the Fe ejecta distribution, density structure, sphericity, and ionization state as a function of expansion velocity, thereby testing SN Ia explosion models with direct Fe-rich ejecta mapping data.

  14. Supernova 2010ev: A reddened high velocity gradient type Ia supernova

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Claudia P.; González-Gaitán, Santiago; Folatelli, Gastón; Pignata, Giuliano; Anderson, Joseph P.; Hamuy, Mario; Morrell, Nidia; Stritzinger, Maximilian; Taubenberger, Stefan; Bufano, Filomena; Olivares E., Felipe; Haislip, Joshua B.; Reichart, Daniel E.

    2016-05-01

    Aims: We present and study the spectroscopic and photometric evolution of the type Ia supernova (SN Ia) 2010ev. Methods: We obtain and analyze multiband optical light curves and optical/near-infrared spectroscopy at low and medium resolution spanning -7 days to +300 days from the B-band maximum. Results: A photometric analysis shows that SN 2010ev is a SN Ia of normal brightness with a light-curve shape of Δm15(B) = 1.12 ± 0.02 and a stretch s = 0.94 ± 0.01 suffering significant reddening. From photometric and spectroscopic analysis, we deduce a color excess of E(B - V) = 0.25 ± 0.05 and a reddening law of Rv = 1.54 ± 0.65. Spectroscopically, SN 2010ev belongs to the broad-line SN Ia group, showing stronger than average Si iiλ6355 absorption features. We also find that SN 2010ev is a high velocity gradient SN with v˙Si = 164 ± 7 km s-1 d-1. The photometric and spectral comparison with other supernovae shows that SN 2010ev has similar colors and velocities to SN 2002bo and SN 2002dj. The analysis of the nebular spectra indicates that the [Fe ii]λ7155 and [Ni ii]λ7378 lines are redshifted, as expected for a high velocity gradient supernova. All these common intrinsic and extrinsic properties of the high velocity gradient (HVG) group are different from the low velocity gradient (LVG) normal SN Ia population and suggest significant variety in SN Ia explosions. This paper includes data gathered with the Du Pont Telescope at Las Campanas Observatory, Chile; and the Gemini Observatory, Cerro Pachon, Chile (Gemini Program GS-2010A-Q-14). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO Programme 085.D-0577).

  15. Supernova 2010ev: A reddened high velocity gradient type Ia supernova

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Claudia P.; González-Gaitán, Santiago; Folatelli, Gastón; Pignata, Giuliano; Anderson, Joseph P.; Hamuy, Mario; Morrell, Nidia; Stritzinger, Maximilian; Taubenberger, Stefan; Bufano, Filomena; Olivares E., Felipe; Haislip, Joshua B.; Reichart, Daniel E.

    2016-04-01

    Aims: We present and study the spectroscopic and photometric evolution of the type Ia supernova (SN Ia) 2010ev. Methods: We obtain and analyze multiband optical light curves and optical/near-infrared spectroscopy at low and medium resolution spanning -7 days to +300 days from the B-band maximum. Results: A photometric analysis shows that SN 2010ev is a SN Ia of normal brightness with a light-curve shape of Δm15(B) = 1.12 ± 0.02 and a stretch s = 0.94 ± 0.01 suffering significant reddening. From photometric and spectroscopic analysis, we deduce a color excess of E(B - V) = 0.25 ± 0.05 and a reddening law of Rv = 1.54 ± 0.65. Spectroscopically, SN 2010ev belongs to the broad-line SN Ia group, showing stronger than average Si iiλ6355 absorption features. We also find that SN 2010ev is a high velocity gradient SN with v˙Si = 164 ± 7 km s-1 d-1. The photometric and spectral comparison with other supernovae shows that SN 2010ev has similar colors and velocities to SN 2002bo and SN 2002dj. The analysis of the nebular spectra indicates that the [Fe ii]λ7155 and [Ni ii]λ7378 lines are redshifted, as expected for a high velocity gradient supernova. All these common intrinsic and extrinsic properties of the high velocity gradient (HVG) group are different from the low velocity gradient (LVG) normal SN Ia population and suggest significant variety in SN Ia explosions. This paper includes data gathered with the Du Pont Telescope at Las Campanas Observatory, Chile; and the Gemini Observatory, Cerro Pachon, Chile (Gemini Program GS-2010A-Q-14). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO Programme 085.D-0577).

  16. Type Ia Supernova Models and Progenitor Scenarios

    NASA Astrophysics Data System (ADS)

    Nomoto, Ken'ichi; Kamiya, Yasuomi; Nakasato, Naohito

    2013-01-01

    We review some recent developments in theoretical studies on the connection between the progenitor systems of Type Ia supernovae (SNe Ia) and the explosion mechanisms. (1) DD-subCh: In the merging of double C+O white dwarfs (DD scenario), if the carbon detonation is induced near the white dwarf (WD) surface in the early dynamical phase, it could result in the (effectively) sub-Chandrasekhar mass explosion. (2) DD-Ch: If no surface C-detonation is ignited, the WD could grow until the Chandrasekhar mass is reached, but the outcome depends on whether the quiescent carbon shell burning is ignited and burns C+O into O+Ne+Mg. (3) SD-subCh: In the single degenerate (SD) scenario, if the He shell-flashes grow strong to induce a He detonation, it leads to the sub-Chandra explosion. (4) SD-Ch: If the He-shell flashes are not strong enough, they still produce interesting amounts of Si and S near the surface of the C+O WD before the explosion. In the Chandra mass explosion, the central density is high enough to produce electron capture elements, e.g., stable 58Ni. Observations of the emission lines of Ni in the nebular spectra provides useful diagnostics of the sub-Chandra vs. Chandra issue. The recent observations of relatively low velocity carbon near the surface of SNe Ia provide also an interesting constraint on the explosion models.

  17. Type Ia supernovae from merging white dwarfs. I. Prompt detonations

    SciTech Connect

    Moll, R.; Woosley, S. E.; Raskin, C.; Kasen, D.

    2014-04-20

    Merging white dwarfs are a possible progenitor of Type Ia supernovae (SNe Ia). Numerical models suggest that a detonation might be initiated before the stars have coalesced to form a single compact object. Here we study such prompt detonations by means of numerical simulations, modeling the disruption and nucleosynthesis of the stars until the ejecta reach the coasting phase, and generating synthetic light curves and spectra. Three models are considered with primary masses 0.96 M {sub ☉}, 1.06 M {sub ☉}, and 1.20 M {sub ☉}. Of these, the 0.96 M {sub ☉} dwarf merging with a 0.81 M {sub ☉} companion, with an {sup 56}Ni yield of 0.58 M {sub ☉}, is the most promising candidate for reproducing common SNe Ia. The more massive mergers produce unusually luminous SNe Ia with peak luminosities approaching those attributed to 'super-Chandrasekhar' mass SNe Ia. While the synthetic light curves and spectra of some of the models resemble observed SNe Ia, the significant asymmetry of the ejecta leads to large orientation effects. The peak bolometric luminosity varies by more than a factor of two with the viewing angle, and the velocities of the spectral absorption features are lower when observed from angles where the light curve is brightest. The largest orientation effects are seen in the ultraviolet, where the flux varies by more than an order of magnitude. The set of three models roughly obeys a width-luminosity relation, with the brighter light curves declining more slowly in the B band. Spectral features due to unburned carbon from the secondary star are also seen in some cases.

  18. Berkeley SuperNova Ia Program (BSNIP): Initial Spectral Analysis

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey; Kong, J.; Ganeshalingam, M.; Li, W.; Filippenko, A. V.

    2011-01-01

    The Berkeley SuperNova Ia Program (BSNIP) has been observing nearby (z < 0.1) Type Ia supernovae (SNe Ia) both photometrically and spectroscopically for over two decades. Using telescopes at both Lick and Keck Observatories, we have amassed an extensive collection of well-sampled optical light curves with complementary spectra covering, on average, 3400-10,000 Å. In total, we have obtained nearly 600 spectra of over 200 SNe Ia with densely sampled multi-color light curves. The initial analysis of this dataset consists of accurately and robustly measuring the strength and position of various spectral features near maximum brightness. We determine the endpoints, pseudo-continuum, expansion velocity, equivalent width, and depth of each major feature observed in our wavelength range. For objects with multiple spectra near maximum brightness we investigate how these values change with time. From these measurements we also calculate velocity gradients and various flux ratios within a given spectrum which will allow us to explore correlations between spectral and photometric observables. Some possible correlations have been studied previously, but our dataset is unique in how self-consistent the data reduction and spectral feature measurements have been, and it is a factor of a few larger than most earlier studies. We will briefly summarize the contents of the full dataset as an introduction to our initial analysis. Some of our measurements of SN Ia spectral features, along with a few initial results from those measurements, will be presented. Finally, we will comment on our current progress and planned future work. We gratefully acknowledge the financial support of NSF grant AST-0908886, the TABASGO Foundation, and the Marc J. Staley Graduate Fellowship in Astronomy.

  19. The diversity of type Ia supernovae from broken symmetries.

    PubMed

    Kasen, D; Röpke, F K; Woosley, S E

    2009-08-13

    Type Ia supernovae result when carbon-oxygen white dwarfs in binary systems accrete mass from companion stars, reach a critical mass and explode. The near uniformity of their light curves makes these supernovae good 'standard candles' for measuring cosmic expansion, but a correction must be applied to account for the fact that the brighter ones have broader light curves. One-dimensional modelling, with a certain choice of parameters, can reproduce this general trend in the width-luminosity relation; but the processes of ignition and detonation have recently been shown to be intrinsically asymmetric, so parameterization must have its limits. Here we report multi-dimensional modelling of the explosion physics and radiative transfer, which reveals that the breaking of spherical symmetry is a critical factor in determining both the width-luminosity relation and the observed scatter about it. The deviation from spherical symmetry can also explain the finite polarization detected in the light from some supernovae. The slope and normalization of the width-luminosity relation has a weak dependence on certain properties of the white dwarf progenitor, in particular the trace abundances of elements other than carbon and oxygen. Failing to correct for this effect could lead to systematic overestimates of up to 2 per cent in the distance to remote supernovae. PMID:19675647

  20. Constraints on the explosion mechanism and progenitors of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Blondin, S.

    2015-12-01

    We present 1D non-LTE time-dependent radiative-transfer simulations of Type Ia supernova ejecta resulting from different explosion mechanisms and white dwarf (WD) progenitor masses, and confront our results to Type Ia supernova observations over the first ˜ 100 d of their evolution. While the ``standard'' Chandrasekhar-mass delayed-detonation model reproduces the observed properties of Type Ia supernova ejecta near maximum light over a wide range of peak luminosities, the high luminosity and blue optical colours seen at early times in several Type Ia supernova ejecta appears to require some hydrodynamical interaction affecting the outermost ejecta layers, here in the form of a strong pulsation. Moreover, the fast light-curve evolution of the least luminous Type Ia supernova ejecta seem to require WD progenitors below the Chandrasekhar mass. The observed diversity of the Type Ia supernova population can thus be reproduced with multiple progenitor channels and explosion mechanisms. In this context, departures from spherical symmetry only play a minor role.

  1. Type Ia Supernova Hubble Residuals and Host-Galaxy Properties

    SciTech Connect

    Nearby Supernova Factory; Kim, A. G.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Feindt, U.; Fleury, M.; Gangler, E.; Greskovic, P.; Guy, J.; Kowalski, M.; Lombardo, S.; Nordin, J.; Nugent, P.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Saunders, C.; Scalzo, R.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.

    2014-01-17

    Kim et al. (2013) [K13] introduced a new methodology for determining peak- brightness absolute magnitudes of type Ia supernovae from multi-band light curves. We examine the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spec- trophotometric time series, with global host-galaxy properties. The K13 Hubble residual step with host mass is 0.013 ? 0.031 mag for a supernova subsample with data coverage corresponding to the K13 training; at ? 1?, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement the Hubble residual step with host mass is 0.045 ? 0.026 mag for the larger sample; a calculation using the modes of the distributions, less sensitive to outliers, yields a step of 0.019 mag. The analysis of this article uses K13 inferred luminosities, as distinguished from previous works that use magnitude corrections as a function of SALT2 color and stretch param- eters: Steps at> 2? significance are found in SALT2 Hubble residuals in samples split by the values of their K13 x(1) and x(2) light-curve parameters. x(1) affects the light- curve width and color around peak (similar to the∆m15 and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20 to 30 days after peak brightness. The novel light-curve analysis, increased parameter set, and magnitude corrections of K13 may be capturing features of SN Ia diversity arising from progenitor stellar evolution.

  2. Type Ia supernova Hubble residuals and host-galaxy properties

    SciTech Connect

    Kim, A. G.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Fleury, M.; Guy, J.; Baltay, C.; Buton, C.; Feindt, U.; Greskovic, P.; Kowalski, M.; Childress, M.; Chotard, N.; Copin, Y.; Gangler, E. [Université de Lyon, F-69622 Lyon; Université de Lyon 1, Villeurbanne; CNRS and others

    2014-03-20

    Kim et al. introduced a new methodology for determining peak-brightness absolute magnitudes of type Ia supernovae from multi-band light curves. We examine the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spectrophotometric time series, with global host-galaxy properties. The K13 Hubble residual step with host mass is 0.013 ± 0.031 mag for a supernova subsample with data coverage corresponding to the K13 training; at <<1σ, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement of the Hubble residual step with the host mass is 0.045 ± 0.026 mag for the larger sample; a calculation using the modes of the distributions, less sensitive to outliers, yields a step of 0.019 mag. The analysis of this article uses K13 inferred luminosities, as distinguished from previous works that use magnitude corrections as a function of SALT2 color and stretch parameters: steps at >2σ significance are found in SALT2 Hubble residuals in samples split by the values of their K13 x(1) and x(2) light-curve parameters. x(1) affects the light-curve width and color around peak (similar to the Δm {sub 15} and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20-30 days after peak brightness. The novel light-curve analysis, increased parameter set, and magnitude corrections of K13 may be capturing features of SN Ia diversity arising from progenitor stellar evolution.

  3. Type Ia Supernova Hubble Residuals and Host-galaxy Properties

    NASA Astrophysics Data System (ADS)

    Kim, A. G.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Feindt, U.; Fleury, M.; Gangler, E.; Greskovic, P.; Guy, J.; Kowalski, M.; Lombardo, S.; Nordin, J.; Nugent, P.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Saunders, C.; Scalzo, R.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.

    2014-03-01

    Kim et al. introduced a new methodology for determining peak-brightness absolute magnitudes of type Ia supernovae from multi-band light curves. We examine the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spectrophotometric time series, with global host-galaxy properties. The K13 Hubble residual step with host mass is 0.013 ± 0.031 mag for a supernova subsample with data coverage corresponding to the K13 training; at Lt1σ, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement of the Hubble residual step with the host mass is 0.045 ± 0.026 mag for the larger sample; a calculation using the modes of the distributions, less sensitive to outliers, yields a step of 0.019 mag. The analysis of this article uses K13 inferred luminosities, as distinguished from previous works that use magnitude corrections as a function of SALT2 color and stretch parameters: steps at >2σ significance are found in SALT2 Hubble residuals in samples split by the values of their K13 x(1) and x(2) light-curve parameters. x(1) affects the light-curve width and color around peak (similar to the Δm 15 and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20-30 days after peak brightness. The novel light-curve analysis, increased parameter set, and magnitude corrections of K13 may be capturing features of SN Ia diversity arising from progenitor stellar evolution.

  4. The VLT Measures the Shape of a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    2003-08-01

    clear until now how similar such an event would appear to observers who view it from different directions. All eggs look similar and indistinguishable from each other when viewed from the same angle, but the side view (oval) is obviously different from the end view (round). And indeed, if Type Ia supernova explosions were asymmetric, they would shine with different brightness in different directions. Observations of different supernovae - seen under different angles - could therefore not be directly compared. Not knowing these angles, however, the astronomers would then infer incorrect distances and the precision of this fundamental method for gauging the structure of the Universe would be in question. Polarimetry to the rescue A simple calculation shows that even to the eagle eyes of the VLT Interferometer (VLTI), all supernovae at cosmological distances will appear as unresolved points of light; they are simply too far. But there is another way to determine the angle at which a particular supernova is viewed: polarimetry is the name of the trick! Polarimetry works as follows: light is composed of electromagnetic waves (or photons) which oscillate in certain directions (planes). Reflection or scattering of light favours certain orientations of the electric and magnetic fields over others. This is why polarising sunglasses can filter out the glint of sunlight reflecting off a pond. When light scatters through the expanding debris of a supernova, it retains information about the orientation of the scattering layers. If the supernova is spherically symmetric, all orientations will be present equally and will average out, so there will be no net polarisation . If, however, the gas shell is not round, a slight net polarisation will be imprinted on the light. " Even for quite noticable asymmetries, however, the polarisation is very small and barely exceeds the level of one percent ", says Dietrich Baade, ESO astronomer and a member of the team that performed the observations

  5. Spectra of High-Redshift Type Ia Supernovae and a Comparison withtheir Low-Redshift Counterparts

    SciTech Connect

    Hook, I.M.; Howell, D.A.; Aldering, G.; Amanullah, R.; Burns,M.S.; Conley, A.; Deustua, S.E.; Ellis, R.; Fabbro, S.; Fadeyev, V.; Folatelli, G.; Garavini, G.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D.E.; Kim, A.G.; Knop, R.A.; Kowalski, M.; Lidman, C.; Nobili, S.; Nugent, P.E.; Pain, R.; Pennypacker, C.R.; Perlmutter, S.; Ruiz-Lapuente,P.; Sainton, G.; Schaefer, B.E.; Smith, E.; Spadafora, A.L.; Stanishev,V.; Thomas, R.C.; Walton, N.A.; Wang, L.; Wood-Vasey, W.M.

    2005-07-20

    We present spectra for 14 high-redshift (0.17 < z < 0.83) supernovae, which were discovered by the Supernova Cosmology Project as part of a campaign to measure cosmological parameters. The spectra are used to determine the redshift and classify the supernova type, essential information if the supernovae are to be used for cosmological studies. Redshifts were derived either from the spectrum of the host galaxy or from the spectrum of the supernova itself. We present evidence that these supernovae are of Type Ia by matching to spectra of nearby supernovae. We find that the dates of the spectra relative to maximum light determined from this fitting process are consistent with the dates determined from the photometric light curves, and moreover the spectral time-sequence for SNe Type Ia at low and high redshift is indistinguishable. We also show that the expansion velocities measured from blueshifted Ca H&K are consistent with those measured for low-redshift Type Ia supernovae. From these first-level quantitative comparisons we find no evidence for evolution in SNIa properties between these low- and high-redshift samples. Thus even though our samples may not be complete, we conclude that there is a population of SNe Ia at high redshift whose spectral properties match those at low redshift.

  6. Spectra and Hubble Space Telescope Light Curves of Six Type Ia Supernovae at 0.511 < z < 1.12 and the Union2 Compilation

    NASA Astrophysics Data System (ADS)

    Amanullah, R.; Lidman, C.; Rubin, D.; Aldering, G.; Astier, P.; Barbary, K.; Burns, M. S.; Conley, A.; Dawson, K. S.; Deustua, S. E.; Doi, M.; Fabbro, S.; Faccioli, L.; Fakhouri, H. K.; Folatelli, G.; Fruchter, A. S.; Furusawa, H.; Garavini, G.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hook, I.; Howell, D. A.; Kashikawa, N.; Kim, A. G.; Knop, R. A.; Kowalski, M.; Linder, E.; Meyers, J.; Morokuma, T.; Nobili, S.; Nordin, J.; Nugent, P. E.; Östman, L.; Pain, R.; Panagia, N.; Perlmutter, S.; Raux, J.; Ruiz-Lapuente, P.; Spadafora, A. L.; Strovink, M.; Suzuki, N.; Wang, L.; Wood-Vasey, W. M.; Yasuda, N.; Supernova Cosmology Project, The

    2010-06-01

    We report on work to increase the number of well-measured Type Ia supernovae (SNe Ia) at high redshifts. Light curves, including high signal-to-noise Hubble Space Telescope data, and spectra of six SNe Ia that were discovered during 2001, are presented. Additionally, for the two SNe with z > 1, we present ground-based J-band photometry from Gemini and the Very Large Telescope. These are among the most distant SNe Ia for which ground-based near-IR observations have been obtained. We add these six SNe Ia together with other data sets that have recently become available in the literature to the Union compilation. We have made a number of refinements to the Union analysis chain, the most important ones being the refitting of all light curves with the SALT2 fitter and an improved handling of systematic errors. We call this new compilation, consisting of 557 SNe, the Union2 compilation. The flat concordance ΛCDM model remains an excellent fit to the Union2 data with the best-fit constant equation-of-state parameter w = -0.997+0.050 -0.054(stat)+0.077 -0.082(stat + sys together) for a flat universe, or w = -1.038+0.056 -0.059(stat)+0.093 -0.097(stat + sys together) with curvature. We also present improved constraints on w(z). While no significant change in w with redshift is detected, there is still considerable room for evolution in w. The strength of the constraints depends strongly on redshift. In particular, at z >~ 1, the existence and nature of dark energy are only weakly constrained by the data. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute (STScI). STScI is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under the NASA contract NAS 5-26555. The observations are associated with programs HST-GO-08585 and HST-GO-09075. Based, in part, on observations obtained at the ESO La Silla Paranal Observatory (ESO programs 67.A-0361 and 169

  7. A Study of Carbon Features in Type Ia Supernova Spectra

    NASA Astrophysics Data System (ADS)

    Parrent, Jerod T.; Thomas, R. C.; Fesen, Robert A.; Marion, G. H.; Challis, Peter; Garnavich, Peter M.; Milisavljevic, Dan; Vinkò, Jòzsef; Wheeler, J. Craig

    2011-05-01

    One of the major differences between various explosion scenarios of Type Ia supernovae (SNe Ia) is the remaining amount of unburned (C+O) material and its velocity distribution within the expanding ejecta. While oxygen absorption features are not uncommon in the spectra of SNe Ia before maximum light, the presence of strong carbon absorption has been reported only in a minority of objects, typically during the pre-maximum phase. The reported low frequency of carbon detections may be due to low signal-to-noise data, low abundance of unburned material, line blending between C II λ6580 and Si II λ6355, ejecta temperature differences, asymmetrical distribution effects, or a combination of these. However, a survey of published pre-maximum spectra reveals that more SNe Ia than previously thought may exhibit C II λ6580 absorption features and relics of line blending near ~6300 Å. Here we present new SN Ia observations where spectroscopic signatures of C II λ6580 are detected and investigate the presence of C II λ6580 in the optical spectra of 19 SNe Ia using the parameterized spectrum synthesis code, SYNOW. Most of the objects in our sample that exhibit C II λ6580 absorption features are of the low-velocity gradient subtype. Our study indicates that the morphology of carbon-rich regions is consistent with either a spherical distribution or a hemispheric asymmetry, supporting the recent idea that SN Ia diversity may be a result of off-center ignition coupled with observer line-of-sight effects.

  8. THE CARNEGIE SUPERNOVA PROJECT: SECOND PHOTOMETRY DATA RELEASE OF LOW-REDSHIFT TYPE Ia SUPERNOVAE

    SciTech Connect

    Stritzinger, Maximilian D.; Phillips, M. M.; Campillay, Abdo; Morrell, Nidia; Krzeminski, Wojtek; Roth, Miguel; Boldt, Luis N.; Burns, Chris; Freedman, Wendy L.; Madore, Barry F.; Persson, Sven E.; Contreras, Carlos; Gonzalez, Sergio; Salgado, Francisco; DePoy, D. L.; Marshall, J. L.; Rheault, Jean-Philippe; Suntzeff, Nicholas B.; Hamuy, Mario E-mail: max@dark-cosmology.dk

    2011-11-15

    The Carnegie Supernova Project (CSP) was a five-year observational survey conducted at Las Campanas Observatory that obtained, among other things, high-quality light curves of {approx}100 low-redshift Type Ia supernovae (SNe Ia). Presented here is the second data release of nearby SN Ia photometry consisting of 50 objects, with a subset of 45 having near-infrared follow-up observations. Thirty-three objects have optical pre-maximum coverage with a subset of 15 beginning at least five days before maximum light. In the near-infrared, 27 objects have coverage beginning before the epoch of B-band maximum, with a subset of 13 beginning at least five days before maximum. In addition, we present results of a photometric calibration program to measure the CSP optical (uBgVri) bandpasses with an accuracy of {approx}1%. Finally, we report the discovery of a second SN Ia, SN 2006ot, similar in its characteristics to the peculiar SN 2006bt.

  9. Type Ia Supernova Spectral Line Ratios as LuminosityIndicators

    SciTech Connect

    Bongard, Sebastien; Baron, E.; Smadja, G.; Branch, David; Hauschildt, Peter H.

    2005-12-07

    Type Ia supernovae have played a crucial role in thediscovery of the dark energy, via the measurement of their light curvesand the determination of the peak brightness via fitting templates to theobserved lightcurve shape. Two spectroscopic indicators are also known tobe well correlated with peak luminosity. Since the spectroscopicluminosity indicators are obtained directly from observed spectra, theywill have different systematic errors than do measurements usingphotometry. Additionally, these spectroscopic indicators may be usefulfor studies of effects of evolution or age of the SNe~;Ia progenitorpopulation. We present several new variants of such spectroscopicindicators which are easy to automate and which minimize the effects ofnoise. We show that these spectroscopic indicators can be measured byproposed JDEM missions such as snap and JEDI.

  10. Critical ingredients of Type Ia supernova radiative-transfer modelling

    NASA Astrophysics Data System (ADS)

    Dessart, Luc; Hillier, D. John; Blondin, Stéphane; Khokhlov, Alexei

    2014-07-01

    We explore the physics of Type Ia supernova (SN Ia) light curves and spectra using the 1D non-local thermodynamic equilibrium (non-LTE) time-dependent radiative-transfer code CMFGEN. Rather than adjusting ejecta properties to match observations, we select as input one `standard' 1D Chandrasekhar-mass delayed-detonation hydrodynamical model, and then explore the sensitivity of radiation and gas properties of the ejecta on radiative-transfer modelling assumptions. The correct computation of SN Ia radiation is not exclusively a solution to an `opacity problem', characterized by the treatment of a large number of lines. We demonstrate that the key is to identify and treat important atomic processes consistently. This is not limited to treating line blanketing in non-LTE. We show that including forbidden-line transitions of metals, and in particular Co, is increasingly important for the temperature and ionization of the gas beyond maximum light. Non-thermal ionization and excitation are also critical since they affect the colour evolution and the ΔM15 decline rate of our model. While impacting little the bolometric luminosity, a more complete treatment of decay routes leads to enhanced line blanketing, e.g. associated with 48Ti in the U and B bands. Overall, we find that SN Ia radiation properties are influenced in a complicated way by the atomic data we employ, so that obtaining converged results is a real challenge. Nonetheless, with our fully fledged CMFGEN model, we obtain good agreement with the golden standard Type Ia SN 2005cf in the optical and near-IR, from 5 to 60 d after explosion, suggesting that assuming spherical symmetry is not detrimental to SN Ia radiative-transfer modelling at these times. Multi-D effects no doubt matter, but they are perhaps less important than accurately treating the non-LTE processes that are crucial to obtain reliable temperature and ionization structures.

  11. Building a Type Ia Supernova Model with SNfactory Spectrophotometric Time Series

    NASA Astrophysics Data System (ADS)

    Saunders, Clare; Nearby Supernova Factory

    2015-01-01

    We present a spectral time series model built using Nearby Supernova Factory (SNfactory) data. The spectrophotometric time series of over one hundred Type Ia supernovae in the data set offer much more information than photometric light curves for use in improving the standardization of Type Ia supernova magnitudes: spectrophotometric observations are interpolated onto a spectral time series surface using Gaussian processes, then Principal Component Analysis (PCA) is used to calculate spectral time series templates. The model is verified using K-fold cross-validation. We discuss the potential for using the PCA coefficients to lower the dispersion in standardized magnitudes on the Hubble diagram.

  12. A Model-independent Photometric Redshift Estimator for Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Wang, Yun

    2007-01-01

    The use of Type Ia supernovae (SNe Ia) as cosmological standard candles is fundamental in modern observational cosmology. In this Letter, we derive a simple empirical photometric redshift estimator for SNe Ia using a training set of SNe Ia with multiband (griz) light curves and spectroscopic redshifts obtained by the Supernova Legacy Survey (SNLS). This estimator is analytical and model-independent it does not use spectral templates. We use all the available SNe Ia from SNLS with near-maximum photometry in griz (a total of 40 SNe Ia) to train and test our photometric redshift estimator. The difference between the estimated redshifts zphot and the spectroscopic redshifts zspec, (zphot-zspec)/(1+zspec), has rms dispersions of 0.031 for 20 SNe Ia used in the training set, and 0.050 for 20 SNe Ia not used in the training set. The dispersion is of the same order of magnitude as the flux uncertainties at peak brightness for the SNe Ia. There are no outliers. This photometric redshift estimator should significantly enhance the ability of observers to accurately target high-redshift SNe Ia for spectroscopy in ongoing surveys. It will also dramatically boost the cosmological impact of very large future supernova surveys, such as those planned for the Advanced Liquid-mirror Probe for Astrophysics, Cosmology, and Asteroids (ALPACA) and the Large Synoptic Survey Telescope (LSST).

  13. Could edge-lit type Ia supernovae be standard candles?

    NASA Astrophysics Data System (ADS)

    Regős, Enikő; Tout, Christopher A.; Wickramasinghe, Dayal; Hurley, Jarrod R.; Pols, Onno R.

    2003-05-01

    The progenitors of Type Ia supernovae (SNe Ia) have not been identified. Though they are no longer fashionable, we investigate the consequences if a significant number of SNe Ia were edge-lit detonations (ELDs) of carbon/oxygen white dwarfs that have accreted a critical mass of helium. Our best understanding of the Phillips relation between light curve speed and peak luminosity assigns both these phenomena to the amount of 56Ni produced. In ELDs there are two sites of 56Ni synthesis. If the peak luminosity is determined primarily by the CO ratio in the core it is primarily a function of the initial main-sequence mass of the progenitor of the CO white dwarf. If the light curve decay speed is determined by the total mass of iron group elements ejected this is a function of the total mass of the ELD at the time of explosion because both the CO core and the He envelope are substantially converted to 56Ni. In general, binary star evolution ensures that these two masses are correlated and an empirical relation between peak luminosity and light curve shape can be expected. However when we perform population synthesis for progenitors of different metallicities we find a systematic shift in this relation that would make distant ELD SNe Ia fainter than those nearby. The abundances of alpha-rich isotopes, such as 44Ca, in the solar system indicate that only about 40 per cent of SNe Ia could be edge-lit so any systematic effect that could be present would be correspondingly diluted. A systematic effect is still expected even if we examine only the small subset of ELDs that accrete from a naked helium star, rather than a He white dwarf.

  14. Tycho Brahe's Supernova: Light from Centuries Past

    NASA Astrophysics Data System (ADS)

    Ruiz-Lapuente, Pilar

    2004-09-01

    The light curve of SN 1572 is described in the terms used nowadays to characterize Type Ia supernovae (SNe Ia). By assembling the records of the observations done in 1572-1574 and evaluating their uncertainties, it is possible to recover the light curve and the color evolution of this supernova. It is found that within the SN Ia family, the event should have been an SN Ia with a normal rate of decline, its stretch factor being s~0.9. The visual light curve near maximum, late-time decline, and color evolution sustain this conclusion. After correcting for extinction, the luminosity of this supernova as observed at maximum is found to be MV=-19.24-5log(D/3.0kpc)+/-0.42. From stretch fitting of the overall light curve, the maximum in V would imply a luminosity difference of +0.17+/-0.1 mag, with the maximum brightness of an s=1 SN Ia. The quantity MV is consistent with a distance of 2.8+/-0.4 kpc for the scale of H0=65 km s-1 Mpc-1.

  15. Radiative transfer and type Ia supernovae spectra analysis in the context of supernovae factory

    NASA Astrophysics Data System (ADS)

    Bongard, Sebastien

    This co-supervised dissertation was conducted in collaboration between The University of Oklahoma City (USA) and University Claude Bernard of Lyon (France). It addresses the radiative transfer issue in type Ia supernovae expanding envelopes, in the context of the SupernovaFactory. We used the multi-purpose radiative transfer code phoenix, developed by P. Hauschildt, F. Allard and E. Baron to produce a grid of synthetic spectra sampling dates from 10 to 25 days after explosion and bolometric magnitudes from -18.0 to -19.7. We also developed an adaptive grid scheme in order to stabilize phoenix convergence. We showed the spectrum formation in SNeIa around maximum light to be a multi- layered process involving regions from 5000 km per s to 20000 km per s, interacting not only through scattering but also through pure emission. This new understanding allowed us to introduce a new spectral indicators we called RSiSu, which can be used to measure SNeIa blue magnitudes with a precision comparable to the stretch factor. This makes it possible to independently constraint the evolutionary effect on SNeIa that are of crucial importance for high z surveys.

  16. FLOYDS Classification of ASASSN-15rv as a Post-Peak Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, G.; Howell, D. A.; Arcavi, I.; McCully, C.; Valenti, S.

    2015-10-01

    We obtained a spectrum of ASASSN-15rv (ATel #8211) on 2015 October 29.6 UT with the robotic FLOYDS instrument mounted on the Faulkes Telescope South. Using Superfit (Howell et al. 2005, ApJ, 634, 119) and SNID (Blondin & Tonry 2007, ApJ, 666, 1024), we find good fits both to Type Ia supernovae 1-2 weeks after maximum light and Type Ic supernovae near maximum light at redshifts around z=0.04.

  17. Using Twin Type Ia Supernovae to Improve Cosmological Distance Measurements

    NASA Astrophysics Data System (ADS)

    Boone, Kyle; Fakhouri, Hannah; Aldering, Greg Scott; Antilogus, Pierre; Aragon, Cecilia; Bailey, Stephen J.; Baltay, Charles; Barbary, Kyle H.; Baugh, Derek; Birchall, Dan; Bongard, Sebastien; Buton, Clement; Cellier-Holzem, Flora; Chen, Juncheng; Childress, Michael; Chotard, Nicolas; Copin, Yannick; Fagrelius, Parker; Feindt, Ulrich; Fleury, Mathilde; Fouchez, Dominique; Gangler, Emmanuel; Hayden, Brian; Kim, Alex G.; Kowalski, Marek; Leget, Pierre-Francois; Lombardo, Simona; Nordin, Jakob; Nugent, Peter E.; Pain, Reynald; Pecontal, Emmanuel; Pereira, Rui; Perlmutter, Saul; Rabinowitz, David L.; Ren, James; Rigault, Mickael; Rubin, David; Runge, Karl; Saunders, Clare; Scalzo, Richard A.; Smadja, Gerard; Sofiatti, Caroline; Strovink, Mark; Suzuki, Nao; Tao, Charling; Thomas, Rollin; Weaver, Benjamin; Nearby Supernova Factory (SNfactory)

    2016-01-01

    The Nearby Supernova Factory has collected spectrophotometric timeseries of many Hubble-flow type Ia supernovae. Using this dataset, we introduce a novel method of identifying "twin" Type Ia supernovae by matching spectral data. For this initial set of SNfactory twin supernovae, we find a dispersion in luminosity of 0.083 ± 0.012 magnitudes between twins, implying a dispersion of 0.072 ± 0.010 magnitudes in the absence of peculiar velocities. This shows that at least 3/4 of the variance in Hubble residuals in current supernova cosmology analyses is due to previously unaccounted-for astrophysical differences among the supernovae -- differences captured by spectrophotometric twinning. We discuss both the usage of this method and the data requirements to implement it.

  18. CONSTRAINING TYPE Ia SUPERNOVAE PROGENITORS FROM THREE YEARS OF SUPERNOVA LEGACY SURVEY DATA

    SciTech Connect

    Bianco, F. B.; Howell, D. A.; Sullivan, M.; Hook, I.; Conley, A.; Kasen, D.; Perlmutter, S.; Gonzalez-Gaitan, S.; Carlberg, R. G.; Perrett, K. M.; Guy, J.; Astier, P.; Balland, C.; Fourmanoit, N.; Hardin, D.; Pain, R.; Fouchez, D.; Lidman, C.; Palanque-Delabrouille, N.

    2011-11-01

    While it is generally accepted that Type Ia supernovae are the result of the explosion of a carbon-oxygen white dwarf accreting mass in a binary system, the details of their genesis still elude us, and the nature of the binary companion is uncertain. Kasen points out that the presence of a non-degenerate companion in the progenitor system could leave an observable trace: a flux excess in the early rise portion of the light curve caused by the ejecta impact with the companion itself. This excess would be observable only under favorable viewing angles, and its intensity depends on the nature of the companion. We searched for the signature of a non-degenerate companion in three years of Supernova Legacy Survey data by generating synthetic light curves accounting for the effects of shocking and comparing true and synthetic time series with Kolmogorov-Smirnov tests. Our most constraining result comes from noting that the shocking effect is more prominent in the rest-frame B than V band: we rule out a contribution from white dwarf-red giant binary systems to Type Ia supernova explosions greater than 10% at the 2{sigma}, and greater than 20% at the 3{sigma} level.

  19. EARLY EMISSION FROM TYPE Ia SUPERNOVAE

    SciTech Connect

    Rabinak, Itay; Waxman, Eli; Livne, Eli

    2012-09-20

    A unique feature of deflagration-to-detonation (DDT) white dwarf explosion models of supernovae of type Ia is the presence of a strong shock wave propagating through the outer envelope. We consider the early emission expected in such models, which is produced by the expanding shock-heated outer part of the ejecta and precedes the emission driven by radioactive decay. We expand on earlier analyses by considering the modification of the pre-detonation density profile by the weak shocks generated during the deflagration phase, the time evolution of the opacity, and the deviation of the post-shock equation of state from that obtained for radiation pressure domination. A simple analytic model is presented and shown to provide an acceptable approximation to the results of one-dimensional numerical DDT simulations. Our analysis predicts a {approx}10{sup 3} s long UV/optical flash with a luminosity of {approx}1 to {approx}3 Multiplication-Sign 10{sup 39} erg s{sup -1}. Lower luminosity corresponds to faster (turbulent) deflagration velocity. The luminosity of the UV flash is predicted to be strongly suppressed at t > t{sub drop} {approx} 1 hr due to the deviation from pure radiation domination.

  20. Turbulence and Combustion in Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Jackson, Aaron; Townsley, Dean; Calder, Alan

    2011-11-01

    Turbulent combustion plays a critical role in Type Ia supernovae, bright astrophysical explosions that serve as cosmological distance indicators. The most successful scenario for reproducing observations involves a deflagration born in the turbulent core a massive C/O white dwarf that subsequently experiences a deflagration-to-detonation transition (DDT) due to turbulence-flame interaction (TFI), although unconfined DDT is poorly understood. Due to the highly non-linear nature of the explosion, the early flame propagation is critically important for determining the explosion outcome. We present full-star, 3D calculations of the deflagration phase of a SNIa explosion. As the flame evolves, it is subject to the Rayleigh-Taylor and Kelvin-Helmholtz instabilities as well as TFI. We analyze the resolved turbulence at the flame front throughout the evolution of the explosion and consider the necessity of modeling unresolved TFI. Furthermore, we consider whether conditions estimated for DDT are likely to occur given the turbulent intensity at the flame front.

  1. THE ABSOLUTE MAGNITUDES OF TYPE Ia SUPERNOVAE IN THE ULTRAVIOLET

    SciTech Connect

    Brown, Peter J.; Roming, Peter W. A.; Ciardullo, Robin; Gronwall, Caryl; Hoversten, Erik A.; Pritchard, Tyler; Milne, Peter; Bufano, Filomena; Mazzali, Paolo; Elias-Rosa, Nancy; Filippenko, Alexei V.; Li Weidong; Foley, Ryan J.; Hicken, Malcolm; Kirshner, Robert P.; Gehrels, Neil; Holland, Stephen T.; Immler, Stefan; Phillips, Mark M.; Still, Martin

    2010-10-01

    We examine the absolute magnitudes and light-curve shapes of 14 nearby (redshift z = 0.004-0.027) Type Ia supernovae (SNe Ia) observed in the ultraviolet (UV) with the Swift Ultraviolet/Optical Telescope. Colors and absolute magnitudes are calculated using both a standard Milky Way extinction law and one for the Large Magellanic Cloud that has been modified by circumstellar scattering. We find very different behavior in the near-UV filters (uvw1{sub rc} covering {approx}2600-3300 A after removing optical light, and u {approx} 3000-4000 A) compared to a mid-UV filter (uvm2 {approx}2000-2400 A). The uvw1{sub rc} - b colors show a scatter of {approx}0.3 mag while uvm2-b scatters by nearly 0.9 mag. Similarly, while the scatter in colors between neighboring filters is small in the optical and somewhat larger in the near-UV, the large scatter in the uvm2 - uvw1 colors implies significantly larger spectral variability below 2600 A. We find that in the near-UV the absolute magnitudes at peak brightness of normal SNe Ia in our sample are correlated with the optical decay rate with a scatter of 0.4 mag, comparable to that found for the optical in our sample. However, in the mid-UV the scatter is larger, {approx}1 mag, possibly indicating differences in metallicity. We find no strong correlation between either the UV light-curve shapes or the UV colors and the UV absolute magnitudes. With larger samples, the UV luminosity might be useful as an additional constraint to help determine distance, extinction, and metallicity in order to improve the utility of SNe Ia as standardized candles.

  2. A strong ultraviolet pulse from a newborn type Ia supernova.

    PubMed

    Cao, Yi; Kulkarni, S R; Howell, D Andrew; Gal-Yam, Avishay; Kasliwal, Mansi M; Valenti, Stefano; Johansson, J; Amanullah, R; Goobar, A; Sollerman, J; Taddia, F; Horesh, Assaf; Sagiv, Ilan; Cenko, S Bradley; Nugent, Peter E; Arcavi, Iair; Surace, Jason; Woźniak, P R; Moody, Daniela I; Rebbapragada, Umaa D; Bue, Brian D; Gehrels, Neil

    2015-05-21

    Type Ia supernovae are destructive explosions of carbon-oxygen white dwarfs. Although they are used empirically to measure cosmological distances, the nature of their progenitors remains mysterious. One of the leading progenitor models, called the single degenerate channel, hypothesizes that a white dwarf accretes matter from a companion star and the resulting increase in its central pressure and temperature ignites thermonuclear explosion. Here we report observations with the Swift Space Telescope of strong but declining ultraviolet emission from a type Ia supernova within four days of its explosion. This emission is consistent with theoretical expectations of collision between material ejected by the supernova and a companion star, and therefore provides evidence that some type Ia supernovae arise from the single degenerate channel. PMID:25993962

  3. Circumstellar material in type Ia supernovae via sodium absorption features.

    PubMed

    Sternberg, A; Gal-Yam, A; Simon, J D; Leonard, D C; Quimby, R M; Phillips, M M; Morrell, N; Thompson, I B; Ivans, I; Marshall, J L; Filippenko, A V; Marcy, G W; Bloom, J S; Patat, F; Foley, R J; Yong, D; Penprase, B E; Beeler, D J; Allende Prieto, C; Stringfellow, G S

    2011-08-12

    Type Ia supernovae are key tools for measuring distances on a cosmic scale. They are generally thought to be the thermonuclear explosion of an accreting white dwarf in a close binary system. The nature of the mass donor is still uncertain. In the single-degenerate model it is a main-sequence star or an evolved star, whereas in the double-degenerate model it is another white dwarf. We show that the velocity structure of absorbing material along the line of sight to 35 type Ia supernovae tends to be blueshifted. These structures are likely signatures of gas outflows from the supernova progenitor systems. Thus, many type Ia supernovae in nearby spiral galaxies may originate in single-degenerate systems. PMID:21836010

  4. THE EXCEPTIONALLY LUMINOUS TYPE Ia SUPERNOVA 2007if

    SciTech Connect

    Yuan, F.; Akerlof, C. W.; Miller, J. M.; McKay, T. A.; Quimby, R. M.; Kulkarni, S.; Wheeler, J. C.; Vinko, J.; Chatzopoulos, E.; Aharonian, F.

    2010-06-01

    SN 2007if was the third over-luminous Type Ia supernova (SN Ia) detected after 2003fg and 2006gz. We present the photometric and spectroscopic observations of the SN and its host by ROTSE-III, HET, and Keck. From the H{sub {alpha}} line identified in the host spectra, we determine a redshift of 0.0736. At this distance, the SN reached an absolute magnitude of -20.4, brighter than any other SNe Ia ever observed. If the source of luminosity is radioactive decay, a large amount of radioactive nickel ({approx}1.5 M {sub sun}) is required to power the peak luminosity, more than can be produced realistically in a Chandrasekhar mass progenitor. Low expansion velocity, similar to that of 2003fg, is also measured around the maximum light. The observations may suggest that SN 2007if was from a massive white dwarf progenitor, plausibly exploding with mass well beyond 1.4 M {sub sun}. Alternatively, we investigate circumstellar interaction that may contribute to the excess luminosity.

  5. Supernova Legacy Survey: using spectral signatures to improve Type Ia supernovae as distance indicators

    NASA Astrophysics Data System (ADS)

    Walker, E. S.; Hook, I. M.; Sullivan, M.; Howell, D. A.; Astier, P.; Balland, C.; Basa, S.; Bronder, T. J.; Carlberg, R.; Conley, A.; Fouchez, D.; Guy, J.; Hardin, D.; Pain, R.; Perrett, K.; Pritchet, C.; Regnault, N.; Rich, J.; Aldering, G.; Fakhouri, H. K.; Kronborg, T.; Palanque-Delabrouille, N.; Perlmutter, S.; Ruhlmann-Kleider, V.; Zhang, T.

    2011-01-01

    Optical long-slit spectroscopy at the Gemini-North telescope using the Gemini Multi-Object Spectrograph (GMOS) was used to classify targets from the Supernova Legacy Survey (SNLS) from 2005 July and 2006 May-2008 May. During this time, 95 objects were observed. Where possible, the objects' redshifts (z) were measured from narrow emission or absorption features in the host galaxy spectrum, otherwise they were measured from the broader supernova features. We present spectra of 68 confirmed or probable SNe Ia from SNLS with redshifts in the range 0.17 ≤z≤ 1.02. In combination with earlier SNLS Gemini and VLT spectra, we used these new observations to measure pseudo-equivalent widths (EWs) of three spectral features - Ca II H&K, Si II and Mg II- in 144 objects and compared them to the EWs of low-redshift SNe Ia from a sample drawn from the literature. No signs of changes with z are seen for the Ca II H&K and Mg II features. Systematically lower EW Si II is seen at high redshift, but this can be explained by a change in demographics of the SNe Ia population within a two-component model combined with an observed correlation between EW Si II and photometric light-curve stretch.

  6. Optimizing the WFIRST Type Ia Supernova Survey

    NASA Astrophysics Data System (ADS)

    Foley, Ryan

    Observations of Type Ia supernovae (SN Ia) led to the discovery that the Universe's expansion is currently accelerating. WFIRST-AFTA is well positioned to provide a generation-defining measurement of the nature of dark energy through its multiple probes, with the WFIRST SN survey projected to have twice the impact as its other probes. Our experienced team includes some of the original discoverers of the accelerating universe, two of the selected ROSES WFIRST preparatory science teams, and the key scientific expertise for the most current and precise SN cosmology results. Our expertise in SN cosmology, SN physics, space-based imaging and spectroscopy, and calibration provide the best foundation upon which a WFIRST SN SIT can be formed. As dark energy is central to NASA's Physics of the Cosmos program, we directly address major objectives of NASA's science program. Moreover, WFIRST is NASA's top priority in the next decade, and preparations now are critical for its eventual success. We present a comprehensive plan to investigate multiple strategies for both optimization and risk mitigation. We have built a simulation framework based on publicly available tools for these evaluations at no cost to this program. Our team has produced the first realistic, full end-to-end simulation of the DRM SN survey, finding that it is suboptimal. After a cursory search of the available parameter space, we were able to find alternative strategies that are significantly better than the DRM strategy. Of course the most optimal strategy will depend on (1) our ability to properly calibrate our data, (2) the data analysis tools available, and (3) our understanding of astrophysical systematic uncertainties. We plan to use much of the next five years to develop strategies to properly calibrate our data, generate software to analyze data from the pixel level to cosmology, and further understand all systematic uncertainties. With the results of these investigations combined with an expanded

  7. Selections from 2015: Two Kinds of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-03-01

    Editors Note:In these last two weeks of 2015, well be looking at a few selections from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume after the AAS winter meeting.The Changing Fractions of Type Ia Supernova NUVOptical Subclasses with RedshiftPublished April2015Main takeaway:A team of scientists led by Peter Milne (University of Arizona) used ultraviolet observations from the Swift spacecraft to determine that type Ia supernovae, stellar explosions previously thought to all belong in the same class, actually fall into two subgroups: those that are slightly redder in NUV wavelengths and those that are slightly bluer.Plot of the percentage of supernovae that are NUV-blue (rather than NUV-red), as a function of redshift. NUV-blue supernovae dominate at higher redshifts. [Milne et al. 2015]Why its interesting:It turns out that the fraction of supernovae in each of these two groups is redshift-dependent. At low redshifts (i.e., nearby), the population of type Ia supernovae is dominated by NUV-red supernovae. At high redshifts (i.e., far away), the population is dominated by NUV-blue supernovae. Since cosmological distances are measured using Type Ia supernovae as standard candles, the fact that weve been modeling these supernovae all the same way (rather than treating them as two separate subclasses) means we may have been systematically misinterpreting distances.What this means for the universes expansion:This seemingly simple discovery carries hefty repercussions in fact, our estimates of the expansion rate of the universe may be incorrect! The authors believe that if we correct for this error, well find that the universe is not expanding as quickly as we thought.CitationPeter A. Milne et al 2015 ApJ 803 20. doi:10.1088/0004-637X/803/1/20

  8. Unburned Material in the Ejecta of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Folatelli, Gastón; Phillips, M. M.; Morrell, Nidia; Tanaka, Masaomi; Maeda, Keiichi; Nomoto, Ken'ichi; Stritzinger, Maximilian; Burns, Christopher R.; Hamuy, Mario; Mazzali, Paolo; Boldt, Luis; Campillay, Abdo; Contreras, Carlos; González, Sergio; Roth, Miguel; Salgado, Francisco; Freedman, W. L.; Madore, Barry F.; Persson, S. E.; Suntzeff, Nicholas B.

    2012-01-01

    The presence of unburned material in the ejecta of normal Type Ia supernovae (SNe Ia) is investigated using early-time spectroscopy obtained by the Carnegie Supernova Project. The tell-tale signature of pristine material from a C+O white dwarf progenitor star is the presence of carbon, as oxygen is also a product of carbon burning. The most prominent carbon lines in optical spectra of SNe Ia are expected to arise from C II. We find that at least 30% of the objects in the sample show an absorption at ≈6300 Å which is attributed to C II λ6580. An alternative identification of this absorption as Hα is considered to be unlikely. These findings imply a larger incidence of carbon in SNe Ia ejecta than previously noted. We show how observational biases and physical conditions may hide the presence of weak C II lines, and account for the scarcity of previous carbon detections in the literature. This relatively large frequency of carbon detections has crucial implications on our understanding of the explosive process. Furthermore, the identification of the 6300 Å absorptions as carbon would imply that unburned material is present at very low expansion velocities, merely ≈1000 km s-1 above the bulk of Si II. Based on spectral modeling, it is found that the detections are consistent with a mass of carbon of 10-3 to 10-2 M ⊙. The presence of this material so deep in the ejecta would imply substantial mixing, which may be related to asymmetries of the flame propagation. Another possible explanation for the carbon absorptions may be the existence of clumps of unburned material along the line of sight. However, the uniformity of the relation between C II and Si II velocities is not consistent with such small-scale asymmetries. The spectroscopic and photometric properties of SNe Ia with and without carbon signatures are compared. A trend toward bluer color and lower luminosity at maximum light is found for objects which show carbon. This paper includes data gathered with

  9. UNBURNED MATERIAL IN THE EJECTA OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Folatelli, Gaston; Tanaka, Masaomi; Maeda, Keiichi; Nomoto, Ken'ichi; Phillips, M. M.; Morrell, Nidia; Campillay, Abdo; Gonzalez, Sergio; Roth, Miguel; Stritzinger, Maximilian; Burns, Christopher R.; Freedman, W. L.; Madore, Barry F; Persson, S. E.; Hamuy, Mario; Mazzali, Paolo; Boldt, Luis; Contreras, Carlos; Salgado, Francisco; Suntzeff, Nicholas B.

    2012-01-20

    The presence of unburned material in the ejecta of normal Type Ia supernovae (SNe Ia) is investigated using early-time spectroscopy obtained by the Carnegie Supernova Project. The tell-tale signature of pristine material from a C+O white dwarf progenitor star is the presence of carbon, as oxygen is also a product of carbon burning. The most prominent carbon lines in optical spectra of SNe Ia are expected to arise from C II. We find that at least 30% of the objects in the sample show an absorption at Almost-Equal-To 6300 A which is attributed to C II {lambda}6580. An alternative identification of this absorption as H{alpha} is considered to be unlikely. These findings imply a larger incidence of carbon in SNe Ia ejecta than previously noted. We show how observational biases and physical conditions may hide the presence of weak C II lines, and account for the scarcity of previous carbon detections in the literature. This relatively large frequency of carbon detections has crucial implications on our understanding of the explosive process. Furthermore, the identification of the 6300 A absorptions as carbon would imply that unburned material is present at very low expansion velocities, merely Almost-Equal-To 1000 km s{sup -1} above the bulk of Si II. Based on spectral modeling, it is found that the detections are consistent with a mass of carbon of 10{sup -3} to 10{sup -2} M{sub Sun }. The presence of this material so deep in the ejecta would imply substantial mixing, which may be related to asymmetries of the flame propagation. Another possible explanation for the carbon absorptions may be the existence of clumps of unburned material along the line of sight. However, the uniformity of the relation between C II and Si II velocities is not consistent with such small-scale asymmetries. The spectroscopic and photometric properties of SNe Ia with and without carbon signatures are compared. A trend toward bluer color and lower luminosity at maximum light is found for

  10. Signatures of Explosion Models of Type Ia Supernovae and Cosmology

    NASA Astrophysics Data System (ADS)

    Höflich, P.

    2005-12-01

    Based on detailed models for the progenitors, explosions, light curves (LCs) and spectra, we discuss signatures of thermonuclear explosions, and the implications for cosmology. Consistency is needed to link observables and explosion physics. Type Ia supernovae (SNe Ia) most probably result from the explosion of a degenerate C/O-White Dwarf (WD) close to the Chandrasekhar mass. There is strong evidence that most of the WD is burned with an extended outer layer of explosive C-burning products (O, Ne, Mg) and very little C remaining. Overall, the chemical structure is radially stratified. This leads to the currently favored delayed detonation model in which a phase of slow nuclear burning as a deflagration front is followed by a detonation phase. The importance of pre-conditioning became obvious. Within an unified scenario, spherical models allow to understand both the homogeneity and basic properties of LCs and spectra, and they allow to probe for their diversity which is a key for high precision cosmology by SNe Ia. For local SNe Ia, the diversity becomes apparent by the combination of high-quality spectra and LCs whereas, for high-z objects, we will rely mostly on information from light curves. Therefore, we emphasize the relation between LC and spectral features. We show how we can actually probe the properties of the progenitor, its environment, and details of the explosion physics. We demonstrate the influence of the metallicity Z on the progenitors, explosion physics and the combined effect on light curves. By and large, a change of Z causes a shift of along the brightness-decline relation because Z shifts the balance between ^{56}Ni and non-radioactive isotopes but hardly changes the energetics or the ^{56}Ni distribution. However, the diversity of the progenitors produces an intrinsic dispersion in B-V which may pose a problem for reddening corrections. We discuss the nature of subluminous SN1999by, and how it can be understood in the same framework as

  11. SNLS: Relating the properties of type Ia supernovae to the stellar populations of their host galaxies

    NASA Astrophysics Data System (ADS)

    Sullivan, M.; Pritchet, C. J.; Le Borgne, D.; Hodsman, A.; Howell, D. A.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K.; Regnault, N.; Rich, J.; Taillet, R.; Baumont, S.; Bronder, J.; Filliol, M.; Perlmutter, S.; Tao, C.; SNLS Collaboration

    2005-12-01

    We examine the rates and properties of type Ia supernovae (SNe Ia) in relation to the physical parameters defining their host galaxy stellar populations. Using a sample of 114 spectroscopically confirmed SNe Ia discovered via the Supernova Legacy Survey (SNLS) distributed over 0.2Ia rate is proportional to the mass-normalised star-formation rate (SFR) of the parent galaxies - more vigorously star-forming galaxies have a higher SN Ia rate. Further, we identify a dependence of the SN rate on both the stellar mass and the current total SFRs of the host systems, suggesting SNe Ia can be generated from both very young and old stellar populations. We further demonstrate a dependence of SN light-curve shapes on the mean age of the stellar population from which the progenitor is drawn -- older systems preferentially host faster/dimmer SNe Ia, as observed in the local Universe. Though with current sample sizes, existing analysis techniques adequately account for these trends when using SNe Ia to constrain cosmological parameters, identifying and understanding the relationship between SNe Ia and their environments will lead to a future improved cosmological candle.

  12. THE MOST SLOWLY DECLINING TYPE Ia SUPERNOVA 2001ay

    SciTech Connect

    Krisciunas, Kevin; Gooding, Samuel D.; Li Weidong E-mail: sam.gooding86@gmail.com

    2011-09-15

    We present optical and near-infrared photometry, as well as ground-based optical spectra and Hubble Space Telescope ultraviolet spectra, of the Type Ia supernova (SN) 2001ay. At maximum light the Si II and Mg II lines indicated expansion velocities of 14,000 km s{sup -1}, while Si III and S II showed velocities of 9000 km s{sup -1}. There is also evidence for some unburned carbon at 12,000 km s{sup -1}. SN 2001ay exhibited a decline-rate parameter of {Delta}m{sub 15}(B) = 0.68 {+-} 0.05 mag; this and the B-band photometry at t {approx}> +25 day past maximum make it the most slowly declining Type Ia SN yet discovered. Three of the four super-Chandrasekhar-mass candidates have decline rates almost as slow as this. After correction for Galactic and host-galaxy extinction, SN 2001ay had M{sub B} = -19.19 and M{sub V} = -19.17 mag at maximum light; thus, it was not overluminous in optical bands. In near-infrared bands it was overluminous only at the 2{sigma} level at most. For a rise time of 18 days (explosion to bolometric maximum) the implied {sup 56}Ni yield was (0.58 {+-} 0.15)/{alpha} M{sub sun}, with {alpha} = L{sub max}/E{sub Ni} probably in the range 1.0-1.2. The {sup 56}Ni yield is comparable to that of many Type Ia SNe. The 'normal' {sup 56}Ni yield and the typical peak optical brightness suggest that the very broad optical light curve is explained by the trapping of {gamma} rays in the inner regions.

  13. COSMOLOGY WITH PHOTOMETRIC SURVEYS OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Gong Yan; Cooray, Asantha; Chen Xuelei

    2010-02-01

    We discuss the extent to which photometric measurements alone can be used to identify Type Ia supernovae (SNIa) and to determine the redshift and other parameters of interest for cosmological studies. We fit the light curve data of the type expected from a survey such as the one planned with the Large Synoptic Survey Telescope (LSST) and also remove the contamination from the core-collapse SNe to SNIa samples. We generate 1000 SNIa mock flux data for each of the LSST filters based on existing design parameters, then use a Markov Chain Monte Carlo analysis to fit the redshift, apparent magnitude, stretch factor, and the phase of the SNIa. We find that the model fitting works adequately well when the true SNe redshift is below 0.5, while at z < 0.2 the accuracy of the photometric data is almost comparable with spectroscopic measurements of the same sample. We discuss the contamination of Type Ib/c (SNIb/c) and Type II supernova (SNII) on the SNIa data set. We find that it is easy to distinguish the SNII through the large chi{sup 2} mismatch when fitting to photometric data with Ia light curves. This is not the case for SNIb/c. We implement a statistical method based on the Bayesian estimation in order to statistically reduce the contamination from SNIb/c for cosmological parameter measurements from the whole SNe sample. The proposed statistical method also evaluates the fraction of the SNIa in the total SNe data set, which provides a valuable guide to establish the degree of contamination.

  14. The Supernova Type Ia Rate Evolution with SNLS

    NASA Astrophysics Data System (ADS)

    Neill, James D.; Sullivan, M.; Balam, D.; Pritchet, C. J.; Howell, D. A.; Perrett, K.; Astier, P.; Aubourg, E.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Pain, R.; Palanque-Delabrouille, N.; Regnault, N.; Rich, J.; Taillet, R.; Aldering, G.; Antilogus, P.; Arsenijevic, V.; Balland, C.; Baumont, S.; Bronder, J.; Ellis, R. S.; Filiol, M.; Gonçalves, A. C.; Hardin, D.; Kowalski, M.; Lidman, C.; Lusset, V.; Mouchet, M.; Mourao, A.; Perlmutter, S.; Ripoche, P.; Schlegel, D.; Tao, C.

    2007-08-01

    We present a progress report on a project to derive the evolution of the volumetric supernova Type Ia rate from the Supernova Legacy Survey. Our preliminary estimate of the rate evolution divides the sample from Neill et al. into two redshift bins: 0.2 < z < 0.4, and 0.4 < z < 0.6. We extend this by adding a bin from the sample analyzed in Sullivan et al. in the range 0.6 < z < 0.75 from the same time period. We compare the derived trend with previously published rates and a supernova Type Ia production model having two components: one component associated closely with star formation and an additional component associated with host galaxy mass. Our observed trend is consistent with this model, which predicts a rising SN Ia rate out to at least z = 2.

  15. SALT spectroscopic classification of PS15bjg as a type-Ia supernova

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Smith, K. W.; Wright, D.; Smartt, S. J.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Colmenero, E. Romero

    2015-07-01

    We obtained SALT (+RSS) spectroscopy of PS15bjg on 2015 July 27.0 UT, covering the wavelength range 350-900 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows PS15bjg to be a normal type-Ia supernova several days before maximum light.

  16. SALT spectroscopic classification of PS15atx as a type-Ia supernova

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Smith, K. W.; Wright, D.; Smartt, S. J.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Depagne, E.

    2015-06-01

    We obtained SALT (+RSS) spectroscopy of PS15atx on 2015 June 20.8 UT, covering the wavelength range 400-950 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows PS15atx to be a normal type-Ia supernova a few days before maximum light.

  17. LINKING TYPE Ia SUPERNOVA PROGENITORS AND THEIR RESULTING EXPLOSIONS

    SciTech Connect

    Foley, Ryan J.; Kirshner, Robert P.; Simon, Joshua D.; Burns, Christopher R.; Gal-Yam, Avishay; Hamuy, Mario; Morrell, Nidia I.; Phillips, Mark M.; Shields, Gregory A.; Sternberg, Assaf

    2012-06-20

    Comparing the ejecta velocities at maximum brightness and narrow circumstellar/interstellar Na D absorption line profiles of a sample of 23 Type Ia supernovae (SNe Ia), we determine that the properties of SN Ia progenitor systems and explosions are intimately connected. As demonstrated by Sternberg et al., half of all SNe Ia with detectable Na D absorption at the host-galaxy redshift in high-resolution spectroscopy have Na D line profiles with significant blueshifted absorption relative to the strongest absorption component, which indicates that a large fraction of SN Ia progenitor systems have strong outflows. In this study, we find that SNe Ia with blueshifted circumstellar/interstellar absorption systematically have higher ejecta velocities and redder colors at maximum brightness relative to the rest of the SN Ia population. This result is robust at a 98.9%-99.8% confidence level, providing the first link between the progenitor systems and properties of the explosion. This finding is further evidence that the outflow scenario is the correct interpretation of the blueshifted Na D absorption, adding additional confirmation that some SNe Ia are produced from a single-degenerate progenitor channel. An additional implication is that either SN Ia progenitor systems have highly asymmetric outflows that are also aligned with the SN explosion or SNe Ia come from a variety of progenitor systems where SNe Ia from systems with strong outflows tend to have more kinetic energy per unit mass than those from systems with weak or no outflows.

  18. Prospective Type Ia supernova surveys from Dome A

    SciTech Connect

    Kim, A.; Bonissent, A.; Christiansen, J. L.; Ealet, A.; Faccioli, L.; Gladney, L.; Kushner, G.; Linder, E.; Stoughton, C.; Wang, L.

    2010-03-10

    Dome A, the highest plateau in Antarctica, is being developed as a site for an astronomical observatory. The planned telescopes and instrumentation and the unique site characteristics are conducive toward Type Ia supernova surveys for cosmology. A self-contained search and survey over 5 years can yield a spectro-photometric time series of ~;; 1000 z< 0:08 supernovae. These can serve to anchor the Hubble diagram and quantify the relationship between luminosities and heterogeneities within the Type Ia supernova class, reducing systematics. Larger aperture (>=4-m) telescopes are capable of discovering supernovae shortly after explosion out to z ~;; 3. These can be fed to space telescopes, and can isolate systematics and extend the redshift range over which we measure the expansion history of the universe.

  19. Prospective Type Ia Supernova Surveys From Dome A

    SciTech Connect

    Kim, A.; Bonissent, A.; Christiansen, J.L.; Ealet, A.; Faccioli, L.; Gladney, L.; Kushner, G.; Linder, E.; Stoughton, C.; Wang, L.; /Texas A-M /Purple Mountain Observ.

    2010-02-01

    Dome A, the highest plateau in Antarctica, is being developed as a site for an astronomical observatory. The planned telescopes and instrumentation and the unique site characteristics are conducive toward Type Ia supernova surveys for cosmology. A self-contained search and survey over five years can yield a spectro-photometric time series of {approx}1000 z < 0.08 supernovae. These can serve to anchor the Hubble diagram and quantify the relationship between luminosities and heterogeneities within the Type Ia supernova class, reducing systematics. Larger aperture ({approx}>4-m) telescopes are capable of discovering supernovae shortly after explosion out to z {approx} 3. These can be fed to space telescopes, and can isolate systematics and extend the redshift range over which we measure the expansion history of the universe.

  20. Progenitors of type Ia supernovae in elliptical galaxies

    SciTech Connect

    Gilfanov, M.; Bogdan, A.

    2011-09-21

    Although there is a nearly universal agreement that type Ia supernovae are associated with the thermonuclear disruption of a CO white dwarf, the exact nature of their progenitors is still unknown. The single degenerate scenario envisages a white dwarf accreting matter from a non-degenerate companion in a binary system. Nuclear energy of the accreted matter is released in the form of electromagnetic radiation or gives rise to numerous classical nova explosions prior to the supernova event. We show that combined X-ray output of supernova progenitors and statistics of classical novae predicted in the single degenerate scenario are inconsistent with X-ray and optical observations of nearby early type galaxies and galaxy bulges. White dwarfs accreting from a donor star in a binary system and detonating at the Chandrasekhar mass limit can account for no more than {approx}5% of type Ia supernovae observed in old stellar populations.

  1. The Peculiar SN 2005hk: Do Some Type Ia Supernovae Explode As Deflagrations?

    SciTech Connect

    Phillips, M.M.; Li, W.; Frieman, J.A.; Blinnikov, S.I.; DePoy, D.; Prieto, J.L.; Milne, P.; Contreras, C.; Folatelli, Gaston; Morrell, N.; Hamuy, M.; Suntzeff, N.B.; Roth, M.; Gonzalez, S.; Krzeminski, W.; Filippenko, A.V.; Freedman, W.L.; Chornock, R.; Jha, S.; Madore, B.F.; Persson, S.E.; /Las Campanas Observ. /UC, Berkeley, Astron. Dept. /Chicago U., Astron. Astrophys. Ctr. /KICP, Chicago /Fermilab /Moscow, ITEP /Garching, Max Planck Inst. /Ohio State U., Dept. Astron. /Arizona U., Astron. Dept. - Steward Observ. /Chile U., Santiago /Texas A-M /Carnegie Inst. Observ. /KIPAC, Menlo Park /Caltech, IPAC /Notre Dame U. /South African Astron. Observ. /Cape Town U. /Washington U., Seattle, Astron. Dept. /New Mexico State U. /Chicago U., FLASH /Baltimore, Space Telescope Sci.

    2006-11-14

    We present extensive u{prime}g{prime}r{prime}i{prime} BV RIY JHK{sub s} photometry and optical spectroscopy of SN 2005hk. These data reveal that SN 2005hk was nearly identical in its observed properties to SN 2002cx, which has been called 'the most peculiar known type Ia supernova'. Both supernovae exhibited high ionization SN 1991T-like pre-maximum spectra, yet low peak luminosities like SN 1991bg. The spectra reveal that SN 2005hk, like SN 2002cx, exhibited expansion velocities that were roughly half those of typical type Ia supernovae. The R and I light curves of both supernovae were also peculiar in not displaying the secondary maximum observed for normal type Ia supernovae. Our Y JH photometry of SN 2005hk reveals the same peculiarity in the near-infrared. By combining our optical and near-infrared photometry of SN 2005hk with published ultraviolet light curves obtained with the Swift satellite, we are able to construct a bolometric light curve from {approx} 10 days before to {approx}60 days after B maximum. The shape and unusually low peak luminosity of this light curve, plus the low expansion velocities and absence of a secondary maximum at red and near-infrared wavelengths, are all in reasonable agreement with model calculations of a 3D deflagration which produces {approx} 0.25 M{sub {circle_dot}} of {sup 56}Ni.

  2. The cosmic gamma-ray background from Type Ia supernovae

    NASA Technical Reports Server (NTRS)

    The, Lih-Sin; Leising, Mark D.; Clayton, Donald D.

    1993-01-01

    We present an improved calculation of the cumulative gamma-ray spectrum of Type Ia supernovae during the history of the universe. We follow Clayton & Ward (1975) in using a few Friedmann models and two simple histories of the average galaxian nucleosynthesis rate, but we improve their calculation by modeling the gamma-ray scattering in detailed numerical models of SN Ia's. The results confirm that near 1 MeV the SN Ia background may dominate, and that it is potentially observable, with high scientific importance. A very accurate measurement of the cosmic background spectrum between 0.1 and 1.0 MeV may reveal the turn-on time and the evolution of the rate of Type Ia supernova nucleosynthesis in the universe.

  3. SPECTRA AND LIGHT CURVES OF FAILED SUPERNOVAE

    SciTech Connect

    Fryer, Chris L.; Dahl, Jon A.; Fontes, Christopher J. E-mail: dahl@lanl.go

    2009-12-10

    Astronomers have proposed a number of mechanisms to produce supernova explosions. Although many of these mechanisms are now not considered primary engines behind supernovae (SNe), they do produce transients that will be observed by upcoming ground-based surveys and NASA satellites. Here, we present the first radiation-hydrodynamics calculations of the spectra and light curves from three of these 'failed' SNe: SNe with considerable fallback, accretion-induced collapse of white dwarfs, and energetic helium flashes (also known as type Ia SNe).

  4. Improved Constraints on Type Ia Supernova Host Galaxy Properties using Multi-Wavelength Photometry and their Correlations with Supernova Properties

    SciTech Connect

    Gupta, Ravi R.; D'Andrea, Chris B.; Sako, Masao; Conroy, Charlie; Smith, Mathew; Bassett, Bruce; Frieman, Joshua A.; Garnavich, Peter M.; Jha, Saurabh W.; Kessler, Richard; Lampeitl, Hubert; /Portsmouth U., ICG /Fermilab

    2011-07-01

    We improve estimates of the stellar mass and mass-weighted average age of Type Ia supernova (SN Ia) host galaxies by combining UV and near-IR photometry with optical photometry in our analysis. Using 206 SNe Ia drawn from the full three-year Sloan Digital Sky Survey (SDSS-II) Supernova Survey (median redshift of z {approx} 0.2) and multi-wavelength host-galaxy photometry from SDSS, the Galaxy Evolution Explorer, and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we present evidence of a correlation (1.9{sigma} confidence level) between the residuals of SNe Ia about the best-fit Hubble relation and the mass-weighted average age of their host galaxies. The trend is such that older galaxies host SNe Ia that are brighter than average after standard light-curve corrections are made. We also confirm, at the 3.0{sigma} level, the trend seen by previous studies that more massive galaxies often host brighter SNe Ia after light-curve correction.

  5. SALT2: using distant supernovae to improve the use of type Ia supernovae as distance indicators

    NASA Astrophysics Data System (ADS)

    Guy, J.; Astier, P.; Baumont, S.; Hardin, D.; Pain, R.; Regnault, N.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Hook, I. M.; Howell, D. A.; Perrett, K.; Pritchet, C. J.; Rich, J.; Sullivan, M.; Antilogus, P.; Aubourg, E.; Bazin, G.; Bronder, J.; Filiol, M.; Palanque-Delabrouille, N.; Ripoche, P.; Ruhlmann-Kleider, V.

    2007-04-01

    Aims:We present an empirical model of type Ia supernovae spectro-photometric evolution with time. Methods: The model is built using a large data set including light-curves and spectra of both nearby and distant supernovae, the latter being observed by the SNLS collaboration. We derive the average spectral sequence of type Ia supernovae and their main variability components including a color variation law. The model allows us to measure distance moduli in the spectral range 2500-8000 Å with calculable uncertainties, including those arising from variability of spectral features. Results: Thanks to the use of high-redshift SNe to model the rest-frame UV spectral energy distribution, we are able to derive improved distance estimates for SNe Ia in the redshift range 0.8Ia supernovae. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. Based on observations obtained at the European Southern Observatory using the Very Large Telescope on the Cerro Paranal (ESO Large Programme 171.A-0486). Based on observations (programs GN-2004A-Q-19, GS-2004A-Q-11, GN-2003B-Q-9, and GS-2003B-Q-8) obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and

  6. Light echoes from ancient supernovae in the Large Magellanic Cloud.

    PubMed

    Rest, Armin; Suntzeff, Nicholas B; Olsen, Knut; Prieto, Jose Luis; Smith, R Chris; Welch, Douglas L; Becker, Andrew; Bergmann, Marcel; Clocchiatti, Alejandro; Cook, Kem; Garg, Arti; Huber, Mark; Miknaitis, Gajus; Minniti, Dante; Nikolaev, Sergei; Stubbs, Christopher

    2005-12-22

    The light from historical supernovae could in principle still be visible as scattered-light echoes centuries after the explosion. The detection of light echoes could allow us to pinpoint the supernova event both in position and age and, most importantly, permit the acquisition of spectra to determine the 'type' of the supernova centuries after the direct light from the explosion first reached Earth. Although echoes have been discovered around some nearby extragalactic supernovae, targeted searches have not found any echoes in the regions of historical Galactic supernovae. Here we report three faint variable-surface-brightness complexes with high apparent proper motions pointing back to three of the six smallest (and probably youngest) previously catalogued supernova remnants in the Large Magellanic Cloud, which are believed to have been thermonuclear (type Ia) supernovae. Using the distance and apparent proper motions of these echo arcs, we estimate ages of 610 and 410 years for two of them. PMID:16372003

  7. Search for surviving companions in type Ia supernova remnants

    SciTech Connect

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E. E-mail: pmricker@illinois.edu E-mail: taam@asiaa.sinica.edu.tw

    2014-09-01

    The nature of the progenitor systems of type Ia supernovae (SNe Ia) is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions (SCs). Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- (MS-) and helium-rich SCs, the color and magnitude of MS- and helium-rich SCs are predicted as functions of time. The SC candidates in Galactic type Ia supernova remnants (Ia SNR) and nearby extragalactic Ia SNRs are discussed. We find that the maximum detectable distance of MS SCs (helium-rich SCs) is 0.6-4 Mpc (0.4-16 Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to search for SCs. However, only five Ia SNRs have been searched for SCs, showing little support for the standard channels in the singe-degenerate scenario. To better understand the progenitors of SNe Ia, we encourage the search for SCs in other nearby Ia SNRs.

  8. Search for Surviving Companions in Type Ia Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E.

    2014-09-01

    The nature of the progenitor systems of type Ia supernovae (SNe Ia) is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions (SCs). Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- (MS-) and helium-rich SCs, the color and magnitude of MS- and helium-rich SCs are predicted as functions of time. The SC candidates in Galactic type Ia supernova remnants (Ia SNR) and nearby extragalactic Ia SNRs are discussed. We find that the maximum detectable distance of MS SCs (helium-rich SCs) is 0.6-4 Mpc (0.4-16 Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to search for SCs. However, only five Ia SNRs have been searched for SCs, showing little support for the standard channels in the singe-degenerate scenario. To better understand the progenitors of SNe Ia, we encourage the search for SCs in other nearby Ia SNRs.

  9. Neutrino event counts from Type Ia supernova models

    NASA Astrophysics Data System (ADS)

    Nagaraj, Gautam; Scholberg, Kate

    2016-01-01

    Core collapse supernovae (SNe) are widely known to be among the universe's primary neutrino factories, releasing ˜99% of their energy, or ˜1053 ergs, in the form of the tiny leptons. On the other hand, less than 4% of the energy of Type Ia SNe is released via neutrinos, hence making Ia SNe impossible to detect (through neutrino observations) at typical supernova distances. For this reason, neutrino signatures from these explosions have very rarely been modeled. We ran time-sliced fluences from non-oscillation pure deflagration and delayed detonation (DDT) Ia models by Odrzywolek and Plewa (2011) through SNOwGLoBES, a software that calculates event rates and other observed quantities of supernova neutrinos in various detectors. We determined Ia neutrino event rates in Hyper-K, a proposed water Cherenkov detector, JUNO, a scintillator detector under construction, and DUNE, a proposed argon detector, and identified criteria to distinguish between the two models (pure deflagration and DDT) based on data from a real supernova (statistically represented by a Poisson distribution around the expected result). We found that up to distances of 8.00, 1.54, and 2.37 kpc (subject to change based on oscillation effects and modified detector efficiencies), we can discern the explosion mechanism with ≥90% confidence in Hyper-K, JUNO, and DUNE, respectively, thus learning more about Ia progenitors.

  10. REVEALING TYPE Ia SUPERNOVA PHYSICS WITH COSMIC RATES AND NUCLEAR GAMMA RAYS

    SciTech Connect

    Horiuchi, Shunsaku; Beacom, John F. E-mail: beacom@mps.ohio-state.ed

    2010-11-01

    Type Ia supernovae (SNe Ia) remain mysterious despite their central importance in cosmology and their rapidly increasing discovery rate. The progenitors of SNe Ia can be probed by the delay time between progenitor birth and explosion as SNe Ia. The explosions and progenitors of SNe Ia can be probed by MeV nuclear gamma rays emitted in the decays of radioactive nickel and cobalt into iron. We compare the cosmic star formation and SN Ia rates, finding that their different redshift evolution requires a large fraction of SNe Ia to have large delay times. A delay-time distribution of the form t {sup -}{alpha} with {alpha} = 1.0 {+-} 0.3 provides a good fit, implying that 50% of SNe Ia explode more than {approx}1 Gyr after progenitor birth. The extrapolation of the cosmic SN Ia rate to z = 0 agrees with the rate we deduce from catalogs of local SNe Ia. We investigate prospects for gamma-ray telescopes to exploit the facts that escaping gamma rays directly reveal the power source of SNe Ia and uniquely provide tomography of the expanding ejecta. We find large improvements relative to earlier studies by Gehrels et al. in 1987 and Timmes and Woosley in 1997 due to larger and more certain SN Ia rates and advances in gamma-ray detectors. The proposed Advanced Compton Telescope, with a narrow-line sensitivity {approx}60 times better than that of current satellites, would, on an annual basis, detect up to {approx}100 SNe Ia (3{sigma}) and provide revolutionary model discrimination for SNe Ia within 20 Mpc, with gamma-ray light curves measured with {approx}10{sigma} significance daily for {approx}100 days. Even more modest improvements in detector sensitivity would open a new and invaluable astronomy with frequent SN Ia gamma-ray detections.

  11. The progenitors of subluminous type Ia supernovae

    SciTech Connect

    Howell, D. Andrew

    2001-02-01

    We find that spectroscopically peculiar subluminous SNe Ia come from an old population. Of the thirteen subluminous SNe Ia known, nine are found in E/S0 galaxies, and the remainder are found in early-type spirals. The probability that this is a chance occurrence is only 0.1%. The finding that subluminous SNe Ia are associated with an older stellar population indicates that for a sufficiently large lookback time (already accessible in current high redshift searches) they will not be found. Due to a scarcity in old populations, hydrogen and helium main sequence stars and He red giant stars that undergo Roche lobe overflow are unlikely to be the progenitors of subluminous SNe Ia. Earlier findings that overluminous SNe Ia (DELTA m{sub 15} (B) < 0.94) come from a young progenitor population are confirmed. The fact that subluminous SNe Ia and overluminous SNe Ia come from different progenitor populations and also have different properties is a prediction of the CO white dwarf merger progenitor scenario.

  12. THE LOW-VELOCITY, RAPIDLY FADING TYPE Ia SUPERNOVA 2002es

    SciTech Connect

    Ganeshalingam, Mohan; Li Weidong; Filippenko, Alexei V.; Silverman, Jeffrey M.; Shen, Ken J.; Chornock, Ryan; Foley, Ryan J.; Kirshner, Robert P.; Calkins, Mike; Matheson, Thomas; Milne, Peter

    2012-06-01

    SN 2002es is a peculiar subluminous Type Ia supernova (SN Ia) with a combination of observed characteristics never before seen in an SN Ia. At maximum light, SN 2002es shares spectroscopic properties with the underluminous SN 1991bg subclass of SNe Ia, but with substantially lower expansion velocities ({approx}6000 km s{sup -1}) more typical of the peculiar SN 2002cx subclass. Photometrically, SN 2002es differs from both SN 1991bg-like and SN 2002cx-like supernovae. Although at maximum light it is subluminous (M{sub B} = -17.78 mag), SN 2002es has a relatively broad light curve ({Delta}m{sub 15}(B) = 1.28 {+-} 0.04 mag), making it a significant outlier in the light-curve width versus luminosity relationship. We estimate a {sup 56}Ni mass of 0.17 {+-} 0.05 M{sub Sun} synthesized in the explosion, relatively low for an SN Ia. One month after maximum light, we find an unexpected plummet in the bolometric luminosity. The late-time decay of the light curves is inconsistent with our estimated {sup 56}Ni mass, indicating that either the light curve was not completely powered by {sup 56}Ni decay or the ejecta became optically thin to {gamma}-rays within a month after maximum light. The host galaxy is classified as an S0 galaxy with little to no star formation, indicating that the progenitor of SN 2002es is likely from an old stellar population. We also present a less extensive data set for SN 1999bh, an object which shares similar photometric and spectroscopic properties. Both objects were found as part of the Lick Observatory Supernova Search, allowing us to estimate that these objects should account for 2.5% of SNe Ia within a fixed volume. Current theoretical models are unable to explain the observed characteristics of SN 2002es.

  13. Asymmetric Explosion of Type Ia Supernovae and Their Observational Signatures

    NASA Astrophysics Data System (ADS)

    Maeda, Keiichi

    2010-06-01

    The nature of Type Ia supernova (SN Ia) explosions has not yet been clarified, despite their importance in astrophysics and cosmology. Recent theoretical investigations suggest that asymmetric distribution of initial thermonuclear sparks may be a key in the SN Ia explosion mechanism. In this paper, the first observational evidence of the asymmetry in SN Ia explosions is presented: We have found that late-time nebular spectra of various SNe Ia show a diversity in wavelengths of emission lines. This feature is inconsistent with any spherically symmetric explosion models, and indicates that the innermost region, a likely product of the deflagration wave propagation, shows an off-set with respect to the explosion center. The diversity in the emission-line wavelengths could naturally be explained by a combination of different viewing angles.

  14. Type Ia supernova remnants: shaping by iron bullets

    NASA Astrophysics Data System (ADS)

    Tsebrenko, Danny; Soker, Noam

    2015-10-01

    Using 2D numerical hydrodynamical simulations of Type Ia supernova remnants (SNR Ia) we show that iron clumps few times denser than the rest of the SN ejecta might form protrusions in an otherwise spherical SNR. Such protrusions exist in some SNR Ia, e.g. SNR 1885 and Tycho. Iron clumps are expected to form in the deflagration to detonation explosion model. In SNR Ia where there are two opposite protrusions, termed `ears', such as Kepler's SNR and SNR G1.9+0.3, our scenario implies that the dense clumps, or iron bullets, were formed along an axis. Such a preferred axis can result from a rotating white dwarf progenitor. If our claim holds, this offers an important clue to the SN Ia explosion scenario.

  15. DISTRIBUTED FLAMES IN TYPE Ia SUPERNOVAE

    SciTech Connect

    Aspden, A. J.; Bell, J. B.; Woosley, S. E.

    2010-02-20

    At a density near a few x10{sup 7} g cm{sup -3}, the subsonic burning in a Type Ia supernova (SN) enters the distributed regime (high Karlovitz number). In this regime, turbulence disrupts the internal structure of the flame, and so the idea of laminar burning propagated by conduction is no longer valid. The nature of the burning in this distributed regime depends on the turbulent Damkoehler number (Da{sub T}), which steadily declines from much greater than one to less than one as the density decreases to a few x10{sup 6} g cm{sup -3}. Classical scaling arguments predict that the turbulent flame speed s{sub T} , normalized by the turbulent intensity u-check, follows s{sub T}/u-check = Da{sub T}{sup 1/2} for Da{sub T} {approx}< 1. The flame in this regime is a single turbulently broadened structure that moves at a steady speed, and has a width larger than the {integral} scale of the turbulence. The scaling is predicted to break down at Da{sub T} {approx} 1, and the flame burns as a turbulently broadened effective unity Lewis number flame. This flame burns locally with speed s{sub l}ambda and width l{sub l}ambda, and we refer to this kind of flame as a lambda-flame. The burning becomes a collection of lambda-flames spread over a region approximately the size of the {integral} scale. While the total burning rate continues to have a well-defined average, s{sub T}{approx}u-check, the burning is unsteady. We present a theoretical framework, supported by both one-dimensional and three-dimensional numerical simulations, for the burning in these two regimes. Our results indicate that the average value of s{sub T} can actually be roughly twice u-check for Da{sub T} {approx}> 1, and that localized excursions to as much as 5 times u-check can occur. We also explore the properties of the individual flames, which could be sites for a transition to detonation when Da{sub T} {approx} 1. The lambda-flame speed and width can be predicted based on the turbulence in the star

  16. Evidence for Ni-56 yields Co-56 yields Fe-56 decay in type Ia supernovae

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc J.; Kirshner, Robert P.; Pinto, Philip A.; Leibundgut, Bruno

    1994-01-01

    In the prevailing picture of Type Ia supernovae (SN Ia), their explosive burning produces Ni-56, and the radioactive decay chain Ni-56 yields Co-56 yields Fe-56 powers the subsequent emission. We test a central feature of this theory by measuring the relative strengths of a (Co III) emission feature near 5900 A and a (Fe III) emission feature near 4700 A. We measure 38 spectra from 13 SN Ia ranging from 48 to 310 days after maximum light. When we compare the observations with a simple multilevel calculation, we find that the observed Fe/Co flux ratio evolves as expected when the Fe-56/Co-56 abundance ratio follows from Ni-56 yields Co-56 yields Fe-56 decay. From this agreement, we conclude that the cobalt and iron atoms we observe through SN Ia emission lines are produced by the radioactive decay of Ni-56, just as predicted by a wide range of models for SN Ia explosions.

  17. Testing the Standardizability of Type Ia Supernovae with the Cepheid Distance of a Twin Supernova

    NASA Astrophysics Data System (ADS)

    Foley, Ryan

    2014-10-01

    Having nearly identical optical light-curve shapes, colors, and spectra, SN 2011by and 2011fe are "twin" Type Ia supernovae (SN Ia). As such, these "standardizable candles" should have identical luminosities. But using independent distance measurements to these SN, their peak luminosity differs by 0.6 mag --- significantly larger than the typical scatter amongst all SN Ia. Differences in their UV spectra indicate that the SN have different metallicities, which could account for the luminosity difference. On the other hand, the distance to SN 2011by, from a Tully-Fisher measurement, may be wrong. We propose to measure a Cepheid distance to SN 2011by to determine if metallicity or an imprecise measurement is causing this large difference.The implications are far reaching for SN cosmology. If the current distance is correct, changing progenitor metallicity could cause large distance biases with redshift. If the distance is revised to bring SN 2011by in line with SN 2011fe, we will infer that metallicity differences are not a large bias for SN cosmology.In the latter case, these data will also provide an additional SN with which we can measure the Hubble constant. Since the number of SN calibrators (only 8 published) limits the precision of our measurement of the Hubble constant, these observations can have a large impact on this measurement.

  18. Near-infrared spectroscopy of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Hsiao, Eric; Phillips, Mark; Burns, Christopher R.; Contreras, Carlos; Gall, Christa; Hoeflich, Peter; Kirshner, Robert P.; Marion, Howie H.; Morrell, Nidia; Sand, David J.; Stritzinger, Maximillian; Carnegie Supernova Project

    2016-01-01

    Improving the cosmological experiments with Type Ia supernovae (SNe Ia) is now not simply a question of observing more supernovae, since any survey, no matter how large, will ultimately be limited by the systematic errors. It has been clearly demonstrated in a number of studies that SNe Ia are better distance indicators in the near-infrared compared to the optical. As exciting as these new results are, SNe Ia in the NIR are expected to be even better than these studies indicate. A key ingredient for improving SN Ia in the NIR as distance indicators is to obtain NIR spectroscopy to determine precise k-corrections, which account for the effect of cosmological expansion upon the measured magnitudes. Better knowledge of the NIR spectroscopic behaviors, akin to that in the optical, is necessary to reach the distance precision required to identify viable models for dark energy. Carnegie Supernova Project II has built a definitive data set, much improved from previous samples, both in size and quality. With this previously unavailable window, we are also beginning to gain new insight on the physics of these events.

  19. Detection of circumstellar material in a normal type Ia supernova.

    PubMed

    Patat, F; Chandra, P; Chevalier, R; Justham, S; Podsiadlowski, Ph; Wolf, C; Gal-Yam, A; Pasquini, L; Crawford, I A; Mazzali, P A; Pauldrach, A W A; Nomoto, K; Benetti, S; Cappellaro, E; Elias-Rosa, N; Hillebrandt, W; Leonard, D C; Pastorello, A; Renzini, A; Sabbadin, F; Simon, J D; Turatto, M

    2007-08-17

    Type Ia supernovae are important cosmological distance indicators. Each of these bright supernovae supposedly results from the thermonuclear explosion of a white dwarf star that, after accreting material from a companion star, exceeds some mass limit, but the true nature of the progenitor star system remains controversial. Here we report the spectroscopic detection of circumstellar material in a normal type Ia supernova explosion. The expansion velocities, densities, and dimensions of the circumstellar envelope indicate that this material was ejected from the progenitor system. In particular, the relatively low expansion velocities suggest that the white dwarf was accreting material from a companion star that was in the red-giant phase at the time of the explosion. PMID:17626848

  20. Neutron excess number and nucleosynthesis of heavy elements in a type Ia supernova explosion

    NASA Astrophysics Data System (ADS)

    Panov, I. V.; Korneev, I. Y.; Blinnikov, S. I.; Röpke, F.

    2016-04-01

    Type Ia supernovae produce very powerful burst of light, which can be observed to high redshift. This fact is very attractive for cosmological applications. For supernova light curve modeling, it is very important to know the amount of Fe and Ni, formed during the explosion. In this paper, we explore both the chemical composition of the ejected supernova shells and the possibility of weak r-process under increased neutron excess number based on a set of trajectories of tracer particles, calculated in a hydrodynamic model of SNIa explosion. It is shown that no r-process elements are synthesized in the considered supernova model, even for an increased neutron excess number ( Y e ˜ 0.4) because of the slow evolution of temperature and density along chosen trajectories. The results of explosive nucleosynthesis are discussed.

  1. The Host Galaxies of Local PTF Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Sullivan, Mark; Howell, D. Andrew; Nugent, Peter; Hook, Isobel; Maguire, Kate; Blake, Sarah; Pan, Yen-Chen

    2012-02-01

    The discovery of correlations between Type Ia Supernova (SN Ia) peak luminosity and the parameters defining their host galaxy stellar populations has important implications for their use as standardised candles. Using new samples of low-redshift SNe Ia located with the Palomar Transient Factory (PTF), a rolling transient search in the local universe, we propose to continue our campaign to study in detail the host galaxies in which SNe Ia explode. We aim to establish which physical variable (metallicity or age) primarily drives the SN Ia luminosity variations using high signal-to-noise spectroscopy of their environments. These data will also improve the derivation of SN Ia "delay-time" distributions, and place tighter constraints on the nature of their progenitor systems. Evolution in SN Ia properties is now the largest single astrophysical systematic in SN Ia cosmology, with host galaxies playing a critical role in cosmological studies, and detailed study of their environments provides a realistic opportunity to improve their use for studying dark energy. We give a status report on the progress of this program to date, and demonstrate the feasibility of our study using our observations from earlier semesters.

  2. PHOTOMETRIC ESTIMATES OF REDSHIFTS AND DISTANCE MODULI FOR TYPE Ia SUPERNOVAE

    SciTech Connect

    Kessler, Richard; Frieman, Joshua A.; Cinabro, David; Bassett, Bruce; Smith, Mathew; Dilday, Benjamin; Jha, Saurabh; Garnavich, Peter M.; Marriner, John; Nichol, Robert C.; Sako, Masao; Bernstein, Joseph P.; Kuhlmann, Stephen; Bizyaev, Dmitry; Goobar, Ariel; Schneider, Donald P.; Stritzinger, Maximilian

    2010-07-01

    Large planned photometric surveys will discover hundreds of thousands of supernovae (SNe), outstripping the resources available for spectroscopic follow-up and necessitating the development of purely photometric methods to exploit these events for cosmological study. We present a light curve fitting technique for type Ia supernova (SN Ia) photometric redshift (photo-z) estimation in which the redshift is determined simultaneously with the other fit parameters. We implement this 'LCFIT+Z' technique within the frameworks of the MLCS2K2 and SALTII light curve fit methods and determine the precision on the redshift and distance modulus. This method is applied to a spectroscopically confirmed sample of 296 SNe Ia from the Sloan Digital Sky Survey-II (SDSS-II) SN Survey and 37 publicly available SNe Ia from the Supernova Legacy Survey (SNLS). We have also applied the method to a large suite of realistic simulated light curves for existing and planned surveys, including the SDSS, SNLS, and the Large Synoptic Survey Telescope. When intrinsic SN color fluctuations are included, the photo-z precision for the simulation is consistent with that in the data. Finally, we compare the LCFIT+Z photo-z precision with previous results using color-based SN photo-z estimates.

  3. Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey M.; Nugent, Peter E.; Gal-Yam, Avishay; Sullivan, Mark; Howell, D. Andrew; Filippenko, Alexei V.; Arcavi, Iair; Ben-Ami, Sagi; Bloom, Joshua S.; Cenko, S. Bradley; Cao, Yi; Chornock, Ryan; Clubb, Kelsey I.; Coil, Alison L.; Foley, Ryan J.; Graham, Melissa L.; Griffith, Christopher V.; Horesh, Assaf; Kasliwal, Mansi M.; Kulkarni, Shrinivas R.; Leonard, Douglas C.; Li, Weidong; Matheson, Thomas; Miller, Adam A.; Modjaz, Maryam; Ofek, Eran O.; Pan, Yen-Chen; Perley, Daniel A.; Poznanski, Dovi; Quimby, Robert M.; Steele, Thea N.; Sternberg, Assaf; Xu, Dong; Yaron, Ofer

    2013-07-01

    Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe Ia) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia shows evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogen-rich CSM; we refer to them as SNe Ia-CSM. In the first systematic search for such systems, we have identified 16 SNe Ia-CSM, and here we present new spectra of 13 of them. Six SNe Ia-CSM have been well studied previously, three were previously known but are analyzed in depth for the first time here, and seven are new discoveries from the Palomar Transient Factory. The spectra of all SNe Ia-CSM are dominated by Hα emission (with widths of ~2000 km s-1) and exhibit large Hα/Hβ intensity ratios (perhaps due to collisional excitation of hydrogen via the SN ejecta overtaking slower-moving CSM shells); moreover, they have an almost complete lack of He I emission. They also show possible evidence of dust formation through a decrease in the red wing of Hα 75-100 days past maximum brightness, and nearly all SNe Ia-CSM exhibit strong Na I D absorption from the host galaxy. The absolute magnitudes (uncorrected for host-galaxy extinction) of SNe Ia-CSM are found to be -21.3 mag <= MR <= -19 mag, and they also seem to show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM are all late-type spirals similar to the Milky Way, or dwarf irregulars like the Large Magellanic Cloud, which implies that these objects come from a relatively young stellar population. This work represents the most detailed analysis of the SN Ia-CSM class to date.

  4. HOST GALAXY PROPERTIES AND HUBBLE RESIDUALS OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY

    SciTech Connect

    Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622, Lyon; Universite de Lyon 1, Villeurbanne; CNRS and others

    2013-06-20

    We examine the relationship between Type Ia supernova (SN Ia) Hubble residuals and the properties of their host galaxies using a sample of 115 SNe Ia from the Nearby Supernova Factory. We use host galaxy stellar masses and specific star formation rates fitted from photometry for all hosts, as well as gas-phase metallicities for a subset of 69 star-forming (non-active galactic nucleus) hosts, to show that the SN Ia Hubble residuals correlate with each of these host properties. With these data we find new evidence for a correlation between SN Ia intrinsic color and host metallicity. When we combine our data with those of other published SN Ia surveys, we find the difference between mean SN Ia brightnesses in low- and high-mass hosts is 0.077 {+-} 0.014 mag. When viewed in narrow (0.2 dex) bins of host stellar mass, the data reveal apparent plateaus of Hubble residuals at high and low host masses with a rapid transition over a short mass range (9.8 {<=} log (M{sub *}/M{sub Sun }) {<=} 10.4). Although metallicity has been a favored interpretation for the origin of the Hubble residual trend with host mass, we illustrate how dust in star-forming galaxies and mean SN Ia progenitor age both evolve along the galaxy mass sequence, thereby presenting equally viable explanations for some or all of the observed SN Ia host bias.

  5. Detection of the gravitational lens magnifying a type Ia supernova.

    PubMed

    Quimby, Robert M; Oguri, Masamune; More, Anupreeta; More, Surhud; Moriya, Takashi J; Werner, Marcus C; Tanaka, Masayuki; Folatelli, Gaston; Bersten, Melina C; Maeda, Keiichi; Nomoto, Ken'ichi

    2014-04-25

    Objects of known brightness, like type Ia supernovae (SNIa), can be used to measure distances. If a massive object warps spacetime to form multiple images of a background SNIa, a direct test of cosmic expansion is also possible. However, these lensing events must first be distinguished from other rare phenomena. Recently, a supernova was found to shine much brighter than normal for its distance, which resulted in a debate: Was it a new type of superluminous supernova or a normal SNIa magnified by a hidden gravitational lens? Here, we report that a spectrum obtained after the supernova faded away shows the presence of a foreground galaxy-the first found to strongly magnify a SNIa. We discuss how more lensed SNIa can be found than previously predicted. PMID:24763586

  6. An Accelerated Radioactive Decay (ARD) Model for Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Rust, Bert W.; Leventhal, Marvin

    2016-01-01

    In 1975, Leventhal and McCall [Nature, 255, 690-692] presented a radioactive decay model 56N i --> 56Co --> 56Fe for the post-peak luminosity decay of Type I supernovae light curves, in which the two decay rates are both accelerated by a common factor. In 1976, Rust, Leventhal and McCall [Nature, 262, 118-120] used sums of exponentials fitting to confirm the acceleration hypothesis, but their result was nevertheless rejected by the astronomical community. Here, we model Type Ia light curves with a system of ODEs (describing the nuclear decays) forced by a Ni-deposition pulse modelled by a 3-parameter Weibull pdf, with all of this occuring in the center of a pre-existing, optically thick, spherical shell which thermalizes the emitted gamma rays. Fitting this model to observed light curves routinely gives fits which account for 99.9+% of the total variance in the observed record. The accelerated decay rates are so stable, for such a long time, that they must occur in an almost unchanging environment -- not it a turbulent expanding atmosphere. The amplitude of the Ni-deposition pulse indicates that its source is the fusion of hydrogen. Carbon and oxygen could not supply the large energy/nucleon that is observed. The secondary peak in the infrared light curve can be easily modelled as a light echo from dust in the back side of the pre-existing shell, and the separation between the peaks indicates a radius of ≈15 light days for the shell. The long-term stability of the acceleration suggests that it is a kinematic effect arising because the nuclear reactions occur either on the surface of a very rapidly rotating condensed object, or in a very tight orbit around such an object, like the fusion pulse in a tokomak reactor.

  7. CIRCUMSTELLAR ABSORPTION IN DOUBLE DETONATION TYPE Ia SUPERNOVAE

    SciTech Connect

    Shen, Ken J.; Guillochon, James; Foley, Ryan J.

    2013-06-20

    Upon formation, degenerate He core white dwarfs are surrounded by a radiative H-rich layer primarily supported by ideal gas pressure. In this Letter, we examine the effect of this H-rich layer on mass transfer in He+C/O double white dwarf binaries that will eventually merge and possibly yield a Type Ia supernova (SN Ia) in the double detonation scenario. Because its thermal profile and equation of state differ from the underlying He core, the H-rich layer is transferred stably onto the C/O white dwarf prior to the He core's tidal disruption. We find that this material is ejected from the binary system and sweeps up the surrounding interstellar medium hundreds to thousands of years before the SN Ia. The close match between the resulting circumstellar medium profiles and values inferred from recent observations of circumstellar absorption in SNe Ia gives further credence to the resurgent double detonation scenario.

  8. Circumstellar Absorption in Double Detonation Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Shen, Ken J.; Guillochon, James; Foley, Ryan J.

    2013-06-01

    Upon formation, degenerate He core white dwarfs are surrounded by a radiative H-rich layer primarily supported by ideal gas pressure. In this Letter, we examine the effect of this H-rich layer on mass transfer in He+C/O double white dwarf binaries that will eventually merge and possibly yield a Type Ia supernova (SN Ia) in the double detonation scenario. Because its thermal profile and equation of state differ from the underlying He core, the H-rich layer is transferred stably onto the C/O white dwarf prior to the He core's tidal disruption. We find that this material is ejected from the binary system and sweeps up the surrounding interstellar medium hundreds to thousands of years before the SN Ia. The close match between the resulting circumstellar medium profiles and values inferred from recent observations of circumstellar absorption in SNe Ia gives further credence to the resurgent double detonation scenario.

  9. Four papers by the Supernova Cosmology Project: (1) Scheduled discoveries of 7+ high-redshift supernovae -- First cosmology results and bounds on q{sub 0}; (2) K corrections for Type Ia supernovae and a test for spatial variation of the Hubble constant; (3) Observation of cosmological time dilation using Type Ia supernovae as clocks; (4) The Type Ia supernova rate at z {approximately} 0.4

    SciTech Connect

    Perlmutter, S.; Deustua, S.; Gabi, S. |

    1995-06-01

    The search for high-redshift Type Ia supernovae discovered, in its first years, a sample of seven supernovae. Using a ``batch`` search strategy, almost all were discovered before maximum light and were observed over the peak of their light curves. The spectra and light curves indicate that almost all were Type Ia supernovae at redshifts z = 0.35--0.5. These high-redshift supernovae can provide a distance indicator and ``standard clock`` to study the cosmological parameters q{sub 0}, {Lambda}, {Omega}{sub 0}, and H{sub 0}. These four presentations discuss observation strategies and rates, analysis and calibration issues, the sources of measurement uncertainty, and the cosmological implications, including bounds on q{sub 0}, of these first high-redshift supernovae from the ongoing search.

  10. Instrument Requirements for Type Ia Supernova Gamma-Ray Studies

    NASA Astrophysics Data System (ADS)

    Leising, M.; Milne, P.; Lara, J.; The, L.

    2004-12-01

    Thermonuclear supernovae are widely used as distance indicators, which yields profound implications, yet details of their progenitor systems and explosion physics remain elusive. It has been argued for thirty-five years that these thoroughly radioactive objects can be understood through detailed gamma-ray line studies, but despite twenty years of gamma-ray instruments in orbit, no Type Ia supernova (SN Ia) has been detected in gamma-ray lines. Still the great promise of gamma-ray studies of SN Ia remains, but the instrument requirements, especially on line sensitivity, are substantial. Finally, a second-generation gamma-ray spectrometer, known now as the Advanced Compton Telescope, is being planned. Considering current SN Ia models of various types, including deflagrations, delayed detonations, and sub-Chandrasekhar-mass detonations, we outline the gamma-ray instrument requirements, especially line flux sensitivity and energy resolution, needed to discriminate among the possible models. We consider realistic SN Ia rates and distributions in space, plausible observing intervals and durations, and the information available from both gamma-ray photometry and spectroscopy. For example, we find that a wide-field compton telescope with energy resolution E/Δ E= 100 in a scanning mode would require broad line sensitivity of 7×10-7 cm-2 s-1 at 847 keV to distinguish deflagration models from delayed detonation models at the rate of one per year.

  11. The host galaxies of local PTF Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Sullivan, Mark; Howell, D. Andrew; Hook, Isobel; Pan, Yen-Chen; Nugent, Peter; Maguire, Kate

    2012-08-01

    The discovery of correlations between Type Ia Supernova (SN Ia) peak luminosity and the parameters defining their host galaxy stellar populations has important implications for their use as standardised candles. Using new samples of low-redshift SNe Ia located with the Palomar Transient Factory (PTF), a rolling transient search in the local universe, we finish our campaign to study in detail the host galaxies in which SNe Ia explode. We aim to establish which physical variable (metallicity or age) primarily drives the SN Ia luminosity variations using high signal-to-noise spectroscopy of their environments. These data will also place tighter constraints on the nature of their progenitor systems. Evolution in SN Ia properties is now the largest single astrophysical systematic in SN Ia cosmology, with host galaxies playing a critical role in cosmological studies, and detailed study of their environments provides a realistic opportunity to improve their use for studying dark energy. We give a status report on the progress of this program to date, and demonstrate the feasibility of our study using our observations from earlier semesters.

  12. DIVERSITY OF TYPE Ia SUPERNOVAE IMPRINTED IN CHEMICAL ABUNDANCES

    SciTech Connect

    Tsujimoto, Takuji; Shigeyama, Toshikazu

    2012-12-01

    A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit an SN-Ia-like elemental feature including a very low [Mg/Fe] ( Almost-Equal-To - 1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr, Mn, Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth and give a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nicely explains the different [Cr, Mn, Ni/Fe] features between the two galaxies as well as the puzzling feature seen in the LMC stars exhibiting very low Ca but normal Mg abundances. Furthermore, the corresponding channel of slow SN Ia is exemplified by performing detailed nucleosynthesis calculations in the scheme of SNe Ia resulting from a 0.8 + 0.6 M{sub Sun} white dwarf merger.

  13. ON IDENTIFYING THE PROGENITORS OF Type Ia SUPERNOVAE

    SciTech Connect

    Livio, Mario; Pringle, J. E.

    2011-10-10

    We propose two new means of identifying the main class of progenitors of Type Ia supernovae-single or double degenerate: (1) if the range of supernova properties is significantly determined by the range of viewing angles of non-spherically symmetric explosions, then the nature of the correlation between polarization and another property (for example, the velocity gradient) can be used to determine the geometry of the asymmetry and hence the nature of the progenitor, and (2) in the double- but not in the single-degenerate case, the range in the observed properties (e.g., velocity gradients) is likely to increase with the amount of carbon seen in the ejecta.

  14. Incorporating Astrophysical Systematics into a Generalized Likelihood for Cosmology with Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Ponder, Kara A.; Wood-Vasey, W. Michael; Zentner, Andrew R.

    2016-07-01

    Traditional cosmological inference using Type Ia supernovae (SNe Ia) have used stretch- and color-corrected fits of SN Ia light curves and assumed a resulting fiducial mean and symmetric intrinsic dispersion for the resulting relative luminosity. As systematics become the main contributors to the error budget, it has become imperative to expand supernova cosmology analyses to include a more general likelihood to model systematics to remove biases with losses in precision. To illustrate an example likelihood analysis, we use a simple model of two populations with a relative luminosity shift, independent intrinsic dispersions, and linear redshift evolution of the relative fraction of each population. Treating observationally viable two-population mock data using a one-population model results in an inferred dark energy equation of state parameter w that is biased by roughly 2 times its statistical error for a sample of N\\quad ≳ \\quad 2500 SNe Ia. Modeling the two-population data with a two-population model removes this bias at a cost of an approximately ∼ 20 % increase in the statistical constraint on w. These significant biases can be realized even if the support for two underlying SNe Ia populations, in the form of model selection criteria, is inconclusive. With the current observationally estimated difference in the two proposed populations, a sample of N\\quad ≳ \\quad 10,000 SNe Ia is necessary to yield conclusive evidence of two populations.

  15. Spectroscopic Classification of AT2016cvv as a normal Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Leonard, D. C.; Sheehan, P.; McCarthy, D.; Follette, K.; Moustakas, J.; Alaniz, M.; Beaumont, C.; Batterman, T.; Black, E.; Bowers, T.; Cryder, M.; Davis, C.; Dawsey, R.; Douglas, E.; Gordon, S.; Gramze, S.; Greiner, M.; Hart, K.; Holt, A.; Hu, J.; Ingebretsen, C.; Iyer, D.; Josephson, R.; Kapko, A.; Keane, J.; Kimberlin, T.; Kinman, S.; Klusmeyer, J.; Kolderup, E.; Kresina, K.; Madden, M.; Meiman, E.; Miniconi, S.; Morton, A.; Neumann, K.; Noguerra, T.; Regester, B.; Regester, J.; Rosenthal, M.; Schlingman, A.; Schlingman, W.; Schlingman, W.; Smith, A.; Svoboda, B.; Watson, L.; Whitesell, R.

    2016-06-01

    We report spectroscopic classification of AT2016cvv (also known as PTSS-16ijc), discovered 2016 June 16.709 UT by the PMO-Tsinghua Supernova Survey (PTSS) in CGCG 280-024 (z=0.044571; Falco et al. 1999, PASP 111, 438, via NED), through inspection of an optical spectrum (range 370-690 nm, resolution 0.8 nm) obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak on 2016 June 19.347 UT. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, ApJ, 666, 1024) and GELATO (Harutyunyan et al. 2008, A & A, 488, 383) finds convincing spectral matches with a number of normal Type-Ia supernovae a few days before maximum light.

  16. Spectroscopic Classification of AT2016cvw as a normal Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Leonard, D. C.; Sheehan, P.; McCarthy, D.; Follette, K.; Moustakas, J.; Alaniz, M.; Beaumont, C.; Batterman, T.; Black, E.; Bowers, T.; Cryder, M.; Davis, C.; Dawsey, R.; Douglas, E.; Gordon, S.; Gramze, S.; Greiner, M.; Hart, K.; Holt, A.; Hu, J.; Ingebretsen, C.; Iyer, D.; Josephson, R.; Kapko, A.; Keane, J.; Kimberlin, T.; Kinman, S.; Klusmeyer, J.; Kolderup, E.; Kresina, K.; Madden, M.; Meiman, E.; Miniconi, S.; Morton, A.; Neumann, K.; Noguerra, T.; Regester, B.; Regester, J.; Rosenthal, M.; Schlingman, A.; Schlingman, W.; Schlingman, W.; Smith, A.; Svoboda, B.; Watson, L.; Whitesell, R.

    2016-06-01

    We report spectroscopic classification of AT2016cvw (also known as PTSS-16ipw), discovered 2016 June 18.813 UT by the PMO-Tsinghua Supernova Survey (PTSS) in MCG +02-58-008 (z=0.038877; Huchra et al. 2012, ApJS, 199, 26, via NED), through inspection of an optical spectrum (range 370-690 nm, resolution 0.8 nm) obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak on 2016 June 20.423 UT. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, ApJ, 666, 1024) and GELATO (Harutyunyan et al. 2008, A & A, 488, 383) finds convincing spectral matches with a number of normal Type-Ia supernovae roughly 3 days before maximum light.

  17. SNLS spectroscopy: testing for evolution in type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Bronder, T. J.; Hook, I. M.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R. G.; Conley, A.; Fouchez, D.; Guy, J.; Howell, D. A.; Neill, J. D.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Sullivan, M.; Baumont, S.; Fabbro, S.; Filliol, M.; Perlmutter, S.; Ripoche, P.

    2008-01-01

    Aims:We present a quantitative study of a new data set of high redshift Type Ia supernovae spectra, observed at the Gemini telescopes during the first 34 months of the Supernova Legacy Survey. During this time 123 supernovae candidates were observed, of which 87 have been identified as SNe Ia at a median redshift of z=0.720. Spectra from the entire second year of the survey and part of the third year (59 total SNe candidates with 46 confirmed SNe Ia) are published here for the first time. The spectroscopic measurements made on this data set are used determine if these distant SNe comprise a population similar to those observed locally. Methods: Rest-frame equivalent width and ejection velocity measurements are made on four spectroscopic features. Corresponding measurements are presented for a set of 167 spectra from 24 low-z SNe Ia from the literature. Results: We show that there exists a sample at high redshift with properties similar to nearby SNe. The high-z measurements are consistent with the range of measurements at low-z and no significant difference was found between the distributions of measurements at low and high redsift for three of the features. The fourth feature displays a possible difference that should be investigated further. Correlations between Type Ia SNe properties and host galaxy morphology were also found to be similar at low and high z, and within each host galaxy class we see no evidence for redshift-evolution in SN properties. A new correlation between SNe Ia peak magnitude and the equivalent width of SiII absorption is presented. Tests on a sub-set of the SNLS SNe demonstrates that this correlation reduces the scatter in SNe Ia luminosity distances in a manner consistent with the lightcurve shape-luminosity corrections that are used for Type Ia SNe cosmology. Conclusions: We show that this new sample of SNLS SNe Ia has spectroscopic properties similar to nearby objects. Tables 6, Appendices A and B are are only available in electronic

  18. The Type-Ia Supernova 1998bu in M96 and the Hubble Constant

    NASA Astrophysics Data System (ADS)

    Jha, S.; Garnavich, P. M.; Challis, P. M.; Kirshner, R. P.; Riess, A. G.; Filippenko, A. V.; Li, W.; Modjaz, M.; Treffers, R. R.; Grebel, E. K.; Seitzer, P.; Jacoby, G. H.; Benson, P. J.; Rizvi, A.; Marschall, L. A.

    1998-12-01

    We present extensive early-time photometric and spectroscopic observations of the type-Ia SN 1998bu in the Leo I Group galaxy M96 (NGC 3368). The well-sampled optical light curves consist of 311 UBVRI observations obtained from several telescopes: the F. L. Whipple Observatory 1.2-m, the MDM Observatory 2.4-m, the WIYN Observatory 3.5-m, the Kitt Peak National Observatory 0.9-m, the Whitin Observatory 0.6-m at Wellesley College, the Gettysburg College Observatory 0.4-m and the 0.76-m Katzman Automatic Imaging Telescope operated by UC Berkeley. The supernova reached maximum brightness in the B band on JD 2450952.8 +/- 0.8, with B = 12.22 +/- 0.03 and V = 11.88 +/- 0.02. There is strong evidence for considerable interstellar extinction along the line of sight to the supernova, but the light curve is otherwise quite typical of type-Ia supernovae (SNe Ia). The distance to M96 has been measured via HST observations of Cepheids in the galaxy (Tanvir et al. 1995), making SN 1998bu very useful in determining the absolute luminosity of SNe Ia. We combine these observations with those of other Cepheid-calibrated SNe Ia and SNe Ia in the Hubble flow and perform a Multicolor Light Curve Shape analysis to derive a Hubble Constant of 64 +/- 4 km/s/Mpc (internal error), but subject to several sources of systematic uncertainty in the Cepheid distance scale.

  19. Learning from the scatter in type ia supernovae

    SciTech Connect

    Dodelson, Scott; Vallinotto, Alberto; /Fermilab /Chicago U.

    2005-11-01

    Type Ia Supernovae are standard candles so their mean apparent magnitude has been exploited to learn about the redshift-distance relationship. Besides intrinsic scatter in this standard candle, additional scatter is caused by gravitational magnification by large scale structure. Here they probe the dependence of this dispersion on cosmological parameters and show that information about the amplitude of clustering, {sigma}{sub s}, is contained in the scatter. In principle, it will be possible to constrain {sigma}{sub s} to within 5% with observations of 2000 Type Ia Supernovae. They identify three sources of systematic error--evolution of intrinsic scatter, baryon contributions to lensing, and non-Gaussianity of lensing--which will make this measurement difficult.

  20. Learning from the scatter in type Ia supernovae

    SciTech Connect

    Dodelson, Scott; Vallinotto, Alberto

    2006-09-15

    Type Ia Supernovae are standard candles so their mean apparent magnitude has been exploited to learn about the redshift-distance relationship. Besides intrinsic scatter in this standard candle, additional scatter is caused by gravitational magnification by large scale structure. Here we probe the dependence of this dispersion on cosmological parameters and show that information about the amplitude of clustering, {sigma}{sub 8}, is contained in the scatter. In principle, it will be possible to constrain {sigma}{sub 8} to within 5% with observations of 2000 Type Ia Supernovae. We identify three sources of systematic error - evolution of intrinsic scatter, baryon contributions to lensing, and non-Gaussianity of lensing - which will make this measurement difficult.

  1. A new hydrodynamics code for Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Leung, S.-C.; Chu, M.-C.; Lin, L.-M.

    2015-12-01

    A two-dimensional hydrodynamics code for Type Ia supernova (SNIa) simulations is presented. The code includes a fifth-order shock-capturing scheme WENO, detailed nuclear reaction network, flame-capturing scheme and sub-grid turbulence. For post-processing, we have developed a tracer particle scheme to record the thermodynamical history of the fluid elements. We also present a one-dimensional radiative transfer code for computing observational signals. The code solves the Lagrangian hydrodynamics and moment-integrated radiative transfer equations. A local ionization scheme and composition dependent opacity are included. Various verification tests are presented, including standard benchmark tests in one and two dimensions. SNIa models using the pure turbulent deflagration model and the delayed-detonation transition model are studied. The results are consistent with those in the literature. We compute the detailed chemical evolution using the tracer particles' histories, and we construct corresponding bolometric light curves from the hydrodynamics results. We also use a GPU to speed up the computation of some highly repetitive subroutines. We achieve an acceleration of 50 times for some subroutines and a factor of 6 in the global run time.

  2. Correlating Type Ia Supernova Properties with Their Local Environment Using HST Snapshots of Host Galaxies

    NASA Astrophysics Data System (ADS)

    Rose, Benjamin; Garnavich, Peter M.

    2016-01-01

    Type Ia supernovae (SN Ia) are important tools for precision cosmology. But there are still uncertainties about how the host galaxy properties and local environment influence the luminosity, color and Hubble residuals of SN Ia. We investigate these questions by analyzing high angular resolution Hubble Space Telescope (HST) imaging of SDSS-II host galaxies. These are "snapshot" images obtained while the telescope was slewing to new targets, so the total exposure times are less than 30 minutes. ACS images were obtained in F475W and F625W filters, similar to SDSS g and r-bands. In total, we observed 61 host galaxies in Stripe 82 that had SN Ia discovered by the SDSS-II SN Survey. HST's resolution and low background allow for detailed analysis of both the region around the SN Ia and the galaxy as a whole. Co-added SDSS-II images of the hosts are used to supplement the HST data in regions of low surface brightness. From this data set we estimate the fractional pixel rank and photometric color of the SN Ia's location and correlate the local environment variables with SN Ia luminosity, light curve width, color and Hubble residual. We assess the impact of these correlations on the accuracy of SN Ia distance estimates and possible biases in measuring the Hubble constant and dark energy parameters.

  3. Progenitors of Type Ia Supernovae: A Panel Discussion

    NASA Astrophysics Data System (ADS)

    Liu, Jifeng

    2011-09-01

    Are single-degenerate models ruled out by X-ray limits? Are double-degenerate models ruled out by insufficient candidates? Are any models consistent with current observations? What can the HEAD community do to address this important issue? Three speakers and a panel of four expert responders will discuss the current status of our understanding of the origins of Type Ia supernovae. Questions and comments from the audience will be welcomed.

  4. NORMAL TYPE Ia SUPERNOVAE FROM VIOLENT MERGERS OF WHITE DWARF BINARIES

    SciTech Connect

    Pakmor, R.; Kromer, M.; Taubenberger, S.; Hillebrandt, W.; Sim, S. A.; Roepke, F. K.

    2012-03-15

    One of the most important questions regarding the progenitor systems of Type Ia supernovae (SNe Ia) is whether mergers of two white dwarfs can lead to explosions that reproduce observations of normal events. Here we present a fully three-dimensional simulation of a violent merger of two carbon-oxygen white dwarfs with masses of 0.9 M{sub Sun} and 1.1 M{sub Sun} combining very high resolution and exact initial conditions. A well-tested combination of codes is used to study the system. We start with the dynamical inspiral phase and follow the subsequent thermonuclear explosion under the plausible assumption that a detonation forms in the process of merging. We then perform detailed nucleosynthesis calculations and radiative transfer simulations to predict synthetic observables from the homologously expanding supernova ejecta. We find that synthetic color light curves of our merger, which produces about 0.62 M{sub Sun} of {sup 56}Ni, show good agreement with those observed for normal SNe Ia in all wave bands from U to K. Line velocities in synthetic spectra around maximum light also agree well with observations. We conclude that violent mergers of massive white dwarfs can closely resemble normal SNe Ia. Therefore, depending on the number of such massive systems available these mergers may contribute at least a small fraction to the observed population of normal SNe Ia.

  5. Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey Michael; Nugent, Peter; Gal-Yam, Avishay; Howell, D. A.; Sullivan, Mark; Filippenko, Alex

    2015-08-01

    Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe Ia) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia shows evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogen-rich CSM; these objects are referred to as SNe Ia-CSM. PTF11kx began life as a SN Ia, but after a month it began to show indications of significant interaction with its CSM. This well-studied object was revolutionary in that in solidified the connection between SNe Ia-CSM and more typical SNe Ia, despite their spectral similarity to Type IIn SNe (which likely come from massive star progenitors, as opposed to the white dwarf progenitors for the SNe Ia-CSM). There are currently nearly 20 SNe Ia-CSM with published data. The spectra of all SNe Ia-CSM are dominated by Hα emission (with widths of ~2000 km s-1) and exhibit large Hα/Hβ intensity ratios (perhaps due to collisional excitation of hydrogen via the SN ejecta overtaking slower-moving CSM shells); moreover, they have an almost complete lack of He I emission. They also show possible evidence of dust formation through a decrease in the red wing of Hα 75-100 days past maximum brightness, and nearly all SNe Ia-CSM exhibit strong Na I D absorption from the host galaxy. The absolute magnitudes (uncorrected for host-galaxy extinction) of SNe Ia-CSM are found to be -21.3 mag ≤ MR ≤ -19 mag, and they also seem to show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM are all late-type spirals similar to the Milky Way, or dwarf irregulars like the Large Magellanic Cloud, which implies that these objects come from a relatively young stellar population.

  6. Observational Clues to the Progenitors of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Maoz, Dan; Mannucci, Filippo; Nelemans, Gijs

    2014-08-01

    Type Ia supernovae (SNe Ia) are important distance indicators, element factories, cosmic-ray accelerators, kinetic-energy sources in galaxy evolution, and end points of stellar binary evolution. It has long been clear that a SN Ia must be the runaway thermonuclear explosion of a degenerate carbon-oxygen stellar core, most likely a white dwarf (WD). However, the specific progenitor systems of SNe Ia, and the processes that lead to their ignition, have not been identified. Two broad classes of progenitor binary systems have long been considered: single-degenerate (SD), in which a WD gains mass from a nondegenerate star; and double-degenerate (DD), involving the merger of two WDs. New theoretical work has enriched these possibilities with some interesting updates and variants. We review the significant recent observational progress in addressing the progenitor problem. We consider clues that have emerged from the observed properties of the various proposed progenitor populations, from studies of SN Ia sites—pre- and postexplosion—from analysis of the explosions themselves and from the measurement of event rates. The recent nearby and well-studied event, SN 2011fe, has been particularly revealing. The observational results are not yet conclusive and sometimes prone to competing theoretical interpretations. Nevertheless, it appears that DD progenitors, long considered the underdog option, could be behind some, if not all, SNe Ia. We point to some directions that may lead to future progress.

  7. IS THERE A HIDDEN HOLE IN TYPE Ia SUPERNOVA REMNANTS?

    SciTech Connect

    Garcia-Senz, D.; Badenes, C.; Serichol, N. E-mail: carles@astro.tau.ac.il

    2012-01-20

    In this paper, we report on the bulk features of the hole carved by the companion star in the material ejected during a Type Ia supernova (SN Ia) explosion. In particular we are interested in the long-term evolution of the hole as well as in its fingerprint in the geometry of the supernova remnant (SNR) after several centuries of evolution, which is a hot topic in current SN Ia studies. We use an axisymmetric smoothed particle hydrodynamics code to characterize the geometric properties of the SNR resulting from the interaction of this ejected material with the ambient medium. Our aim is to use SNR observations to constrain the single degenerate scenario for SN Ia progenitors. Our simulations show that the hole will remain open during centuries, although its partial or total closure at later times due to hydrodynamic instabilities is not excluded. Close to the edge of the hole, the Rayleigh-Taylor instability grows faster, leading to plumes that approach the edge of the forward shock. We also discuss other geometrical properties of the simulations, like the evolution of the contact discontinuity.

  8. Optical and NIR observations of the nearby type Ia supernova SN 2014J

    NASA Astrophysics Data System (ADS)

    Srivastav, Shubham; Ninan, J. P.; Kumar, B.; Anupama, G. C.; Sahu, D. K.; Ojha, D. K.; Prabhu, T. P.

    2016-03-01

    Optical and NIR observations of the Type Ia supernova SN 2014J in M82 are presented. The observed light curves are found to be similar to normal Type Ia supernovae (SNe Ia), with a decline rate parameter Δm15(B) = 1.08 ± 0.03. The supernova reached B-band maximum on JD 2456690.14, at an apparent magnitude mB(max) = 11.94. The optical spectra show a red continuum with deep interstellar Na I absorption, but otherwise resemble those of normal SNe Ia. The Si II λ6355 feature indicates a velocity of ˜12 000 km s-1 at B-band maximum, which places SN 2014J at the border of the normal velocity and high velocity group of SNe Ia. The velocity evolution of SN 2014J places it in the Low Velocity Gradient subclass, whereas the equivalent widths of Si II features near B-band maximum place it at the border of the core normal and Broad Line subclasses of SNe Ia. An analytic model fit to the bolometric light curve indicates that a total of ˜1.3 M⊙ was ejected in the explosion, and the ejected 56Ni mass MNi ˜ 0.6 M⊙. The low [Fe III] λ4701 to [Fe II] λ5200 ratio in the nebular spectra of SN 2014J hints towards clumpiness in the ejecta. Optical broad-band, linear polarimetric observations of SN 2014J obtained on four epochs indicate an almost constant polarization (PR ˜2.7 per cent; θ ˜ 37°), which suggests that the polarization signal is of interstellar origin.

  9. Supernova Emulators: Connecting Massively Parallel SN Ia Radiative Transfer Simulations to Data with Gaussian Processes

    NASA Astrophysics Data System (ADS)

    Goldstein, Daniel; Thomas, Rollin; Kasen, Daniel

    2015-01-01

    Collaboration between the type Ia supernova (SN Ia) modeling and observation communities hinges on our ability to directly connect simulations to data. Here we introduce supernova emulation, a method for facilitating such a connection. Emulation allows us to instantaneously predict the observables (light curves, spectra, spectral time series) generated by arbitrary SN Ia radiative transfer simulations, with estimates of prediction error. Emulators learn the mapping between physically meaningful simulation inputs and the resulting synthetic observables from a training set of simulation input-output pairs. In our emulation framework, we model PCA-decomposed representations of simulated observables as an ensemble of Gaussian Processes. As a proof of concept, we train a bolometric light curve (BLC) emulator on a grid of 400 simulation inputs and BLCs synthesized with the publicly available, gray, time-dependent Monte Carlo expanding atmospheres code, SMOKE. We emulate SMOKE simulations evaluated at a set of 100 out-of-sample input parameters, and achieve excellent agreement between the emulator predictions and the simulated BLCs. In addition to predicting simulation outputs, emulators allow us to infer the regions of simulation input parameter space that correspond to observed SN Ia light curves and spectra. We present a Bayesian framework for solving this inverse problem using Markov Chain Monte Carlo sampling. We fit published bolometric light curves with our emulator and obtain reconstructed masses (nickel mass, total ejecta mass) in agreement with reconstructions from semi-analytic models. We discuss applications of emulation to supernova cosmology and physics, including how emulators can be used to identify and quantify astrophysical sources of systematic error affecting SNe Ia as distance indicators for cosmology.

  10. The Type Ia supernova 1989B in NGC 3627 (M66)

    NASA Technical Reports Server (NTRS)

    Wells, Lisa A.; Phillips, M. M.; Suntzeff, Nicholas B.; Heathcote, S. R.; Hamuy, Mario; Navarrete, M.; Fernandez, M.; Weller, W. G.; Schommer, R. A.; Kirshner, Robert P.

    1994-01-01

    We report extensive optical photometry and spectroscopy of the Type Ia supernova 1989B. Maximum light in B occurred approximately seven days after discovery on JD 2447565.3 +/- 1.0 (1989 February 7.8 +/- 1.0) at a magnitude of 12.34 +/- 0.05. The UBV light curves of this supernova were very similar to those of other well observed Type Ia events such as SN 1981B and SN 1980N. From a comparison of the UBVRIJHK photometry, we derive an extinction for SN 1989B of E(B-V) = 0.37 +/- 0.03 mags relative to the unobscured Type Ia SN 1980N. The properties of the dust responsible for the reddening of SN 1989B appear to have been similar to those of normal dust in the Milky Way. In particular, we find no evidence for an unusually low value of the ratio of the total to selective absorption. We derive a distance modulus of delta mu(sub 0) = -1.62 +/- 0.03 mag relative to the Type Ia SN 1980N. We present optical spectra which provide essentially continuous coverage of the spectral evolution of SN 1989B over the first month following B maximum. These data show the transition from the maximum-light spectrum, in which lines of elements such as Ca, Si, S, Mg, and O are most prominent, to the Fe-dominated spectrum observed a few weeks after maximum. This transition occurred quite smoothly over a two-week period following B maximum. Comparison of the spectra of SN 1989B with data for two other well observed Type Ia supernovae -- 1981B and 1986G -- reveals subtle differences in the relative strengths of the S II and Si II absorption lines at maximum light. However, these differences disappeared within a week or so after maximum with the onset of the Fe-dominated phase.

  11. THE SUBLUMINOUS SUPERNOVA 2007qd: A MISSING LINK IN A FAMILY OF LOW-LUMINOSITY TYPE Ia SUPERNOVAE

    SciTech Connect

    McClelland, Colin M.; Garnavich, Peter M.; Galbany, LluIs; Miquel, Ramon; Foley, Ryan J.; Filippenko, Alexei V.; Bassett, Bruce; Wheeler, J. Craig; Goobar, Ariel; Jha, Saurabh W.; Sako, Masao; Frieman, Joshua A.; Sollerman, Jesper; Vinko, Jozsef; Schneider, Donald P.

    2010-09-01

    We present multi-band photometry and multi-epoch spectroscopy of the peculiar Type Ia supernova (SN Ia) 2007qd, discovered by the SDSS-II Supernova Survey. It possesses physical properties intermediate to those of the peculiar SN 2002cx and the extremely low-luminosity SN 2008ha. Optical photometry indicates that it had an extraordinarily fast rise time of {approx}<10 days and a peak absolute B magnitude of -15.4 {+-} 0.2 at most, making it one of the most subluminous SN Ia ever observed. Follow-up spectroscopy of SN 2007qd near maximum brightness unambiguously shows the presence of intermediate-mass elements which are likely caused by carbon/oxygen nuclear burning. Near maximum brightness, SN 2007qd had a photospheric velocity of only 2800 km s{sup -1}, similar to that of SN 2008ha but about 4000 and 7000 km s{sup -1} less than that of SN 2002cx and normal SN Ia, respectively. We show that the peak luminosities of SN 2002cx like objects are highly correlated with both their light-curve stretch and photospheric velocities. Its strong apparent connection to other SN 2002cx like events suggests that SN 2007qd is also a pure deflagration of a white dwarf, although other mechanisms cannot be ruled out. It may be a critical link between SN 2008ha and the other members of the SN 2002cx like class of objects.

  12. The Supernova Legacy Survey 3-year sample: Type Ia supernovae photometric distances and cosmological constraints

    NASA Astrophysics Data System (ADS)

    Guy, J.; Sullivan, M.; Conley, A.; Regnault, N.; Astier, P.; Balland, C.; Basa, S.; Carlberg, R. G.; Fouchez, D.; Hardin, D.; Hook, I. M.; Howell, D. A.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K. M.; Pritchet, C. J.; Rich, J.; Ruhlmann-Kleider, V.; Balam, D.; Baumont, S.; Ellis, R. S.; Fabbro, S.; Fakhouri, H. K.; Fourmanoit, N.; González-Gaitán, S.; Graham, M. L.; Hsiao, E.; Kronborg, T.; Lidman, C.; Mourao, A. M.; Perlmutter, S.; Ripoche, P.; Suzuki, N.; Walker, E. S.

    2010-11-01

    Aims: We present photometric properties and distance measurements of 252 high redshift Type Ia supernovae (0.15 < z < 1.1) discovered during the first three years of the Supernova Legacy Survey (SNLS). These events were detected and their multi-colour light curves measured using the MegaPrime/MegaCam instrument at the Canada-France-Hawaii Telescope (CFHT), by repeatedly imaging four one-square degree fields in four bands. Follow-up spectroscopy was performed at the VLT, Gemini and Keck telescopes to confirm the nature of the supernovae and to measure their redshifts. Methods: Systematic uncertainties arising from light curve modeling are studied, making use of two techniques to derive the peak magnitude, shape and colour of the supernovae, and taking advantage of a precise calibration of the SNLS fields. Results: A flat ΛCDM cosmological fit to 231 SNLS high redshift type Ia supernovae alone gives Ω_M = 0.211 ± 0.034(stat) ± 0.069(sys). The dominant systematic uncertainty comes from uncertainties in the photometric calibration. Systematic uncertainties from light curve fitters come next with a total contribution of ±0.026 on Ω_M. No clear evidence is found for a possible evolution of the slope (β) of the colour-luminosity relation with redshift. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. Based on observations obtained at the European Southern Observatory using the Very Large Telescope on the Cerro Paranal (ESO Large Programme 171.A-0486 & 176.A-0589). Based on

  13. Single-degenerate Type Ia Supernovae Are Preferentially Overluminous

    NASA Astrophysics Data System (ADS)

    Fisher, Robert; Jumper, Kevin

    2015-06-01

    Recent observational and theoretical progress has favored merging and helium-accreting sub-Chandrasekhar mass white dwarfs (WDs) in the double-degenerate and the double-detonation channels, respectively, as the most promising progenitors of normal Type Ia supernovae (SNe Ia). Thus the fate of rapidly accreting Chandrasekhar mass WDs in the single-degenerate channel remains more mysterious then ever. In this paper, we clarify the nature of ignition in Chandrasekhar-mass single-degenerate SNe Ia by analytically deriving the existence of a characteristic length scale which establishes a transition from central ignitions to buoyancy-driven ignitions. Using this criterion, combined with data from three-dimensional simulations of convection and ignition, we demonstrate that the overwhelming majority of ignition events within Chandrasekhar-mass WDs in the single-degenerate channel are buoyancy-driven, and consequently lack a vigorous deflagration phase. We thus infer that single-degenerate SNe Ia are generally expected to lead to overluminous 1991T-like SNe Ia events. We establish that the rates predicted from both the population of supersoft X-ray sources (SSSs) and binary population synthesis models of the single-degenerate channel are broadly consistent with the observed rates of overluminous SNe Ia, and suggest that the population of SSSs are the dominant stellar progenitors of SNe 1991T-like events. We further demonstrate that the single-degenerate channel contribution to the normal and failed 2002cx-like rates is not likely to exceed 1% of the total SNe Ia rate. We conclude with a range of observational tests of overluminous SNe Ia which will either support or strongly constrain the single-degenerate scenario.

  14. SN 1991bg - A type Ia supernova with a difference

    NASA Technical Reports Server (NTRS)

    Leibundgut, Bruno; Kirshner, Robert P.; Phillips, Mark M.; Wells, Lisa A.; Suntzeff, N. B.; Hamuy, Mario; Schommer, R. A.; Walker, A. R.; Gonzalez, L.; Ugarte, P.

    1993-01-01

    While SN 1991bg is an unusual type Ia SN in such a feature as the brief duration of the photospheric phase, which ended only two weeks after maximum, it shares with other Ia SNs strong Si II and Ca II lines near maximum light. In addition, the light and color curve slopes are almost identical with the templates at late times. The spectral evolution of SN 1991bg is also unique but not unrecognizable; nevertheless, the peculiarities associated with this event complicate the fundamental question as to whether the Ia SNs make good standard candles.

  15. Spectroscopic Properties of Star-Forming Host Galaxies and Type Ia Supernova Hubble Residuals in a Nearly Unbiased Sample

    SciTech Connect

    D'Andrea, Chris B.; et al.

    2011-12-20

    We examine the correlation between supernova host galaxy properties and their residuals on the Hubble diagram. We use supernovae discovered during the Sloan Digital Sky Survey II - Supernova Survey, and focus on objects at a redshift of z < 0.15, where the selection effects of the survey are known to yield a complete Type Ia supernova sample. To minimize the bias in our analysis with respect to measured host-galaxy properties, spectra were obtained for nearly all hosts, spanning a range in magnitude of -23 < M_r < -17. In contrast to previous works that use photometric estimates of host mass as a proxy for global metallicity, we analyze host-galaxy spectra to obtain gas-phase metallicities and star-formation rates from host galaxies with active star formation. From a final sample of ~ 40 emission-line galaxies, we find that light-curve corrected Type Ia supernovae are ~ 0.1 magnitudes brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (> 3{\\sigma}) correlation between the Hubble residuals of Type Ia supernovae and the specific star-formation rate of the host galaxy. We comment on the importance of supernova/host-galaxy correlations as a source of systematic bias in future deep supernova surveys.

  16. Cosmology with Photometrically Classified Type Ia Supernovae from the SDSS-II Supernova Survey

    NASA Astrophysics Data System (ADS)

    Campbell, Heather; D'Andrea, Chris B.; Nichol, Robert C.; Sako, Masao; Smith, Mathew; Lampeitl, Hubert; Olmstead, Matthew D.; Bassett, Bruce; Biswas, Rahul; Brown, Peter; Cinabro, David; Dawson, Kyle S.; Dilday, Ben; Foley, Ryan J.; Frieman, Joshua A.; Garnavich, Peter; Hlozek, Renee; Jha, Saurabh W.; Kuhlmann, Steve; Kunz, Martin; Marriner, John; Miquel, Ramon; Richmond, Michael; Riess, Adam; Schneider, Donald P.; Sollerman, Jesper; Taylor, Matt; Zhao, Gong-Bo

    2013-02-01

    We present the cosmological analysis of 752 photometrically classified Type Ia Supernovae (SNe Ia) obtained from the full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented with host-galaxy spectroscopy from the SDSS-III Baryon Oscillation Spectroscopic Survey. Our photometric-classification method is based on the SN classification technique of Sako et al., aided by host-galaxy redshifts (0.05 < z < 0.55). SuperNova ANAlysis simulations of our methodology estimate that we have an SN Ia classification efficiency of 70.8%, with only 3.9% contamination from core-collapse (non-Ia) SNe. We demonstrate that this level of contamination has no effect on our cosmological constraints. We quantify and correct for our selection effects (e.g., Malmquist bias) using simulations. When fitting to a flat ΛCDM cosmological model, we find that our photometric sample alone gives Ω m = 0.24+0.07 -0.05 (statistical errors only). If we relax the constraint on flatness, then our sample provides competitive joint statistical constraints on Ω m and ΩΛ, comparable to those derived from the spectroscopically confirmed Three-year Supernova Legacy Survey (SNLS3). Using only our data, the statistics-only result favors an accelerating universe at 99.96% confidence. Assuming a constant wCDM cosmological model, and combining with H 0, cosmic microwave background, and luminous red galaxy data, we obtain w = -0.96+0.10 -0.10, Ω m = 0.29+0.02 -0.02, and Ω k = 0.00+0.03 -0.02 (statistical errors only), which is competitive with similar spectroscopically confirmed SNe Ia analyses. Overall this comparison is reassuring, considering the lower redshift leverage of the SDSS-II SN sample (z < 0.55) and the lack of spectroscopic confirmation used herein. These results demonstrate the potential of photometrically classified SN Ia samples in improving cosmological constraints.

  17. SINGLE-DEGENERATE TYPE Ia SUPERNOVAE WITHOUT HYDROGEN CONTAMINATION

    SciTech Connect

    Justham, Stephen

    2011-04-01

    The lack of hydrogen in spectra of type Ia supernovae (SNe Ia) is often seen as troublesome for single-degenerate (SD) progenitor models. We argue that, since continued accretion of angular momentum can prevent explosion of the white dwarf, it may be natural for the donor stars in SD progenitors of SNe Ia to exhaust their envelopes and shrink rapidly before the explosion. This outcome seems most likely for SD SN Ia progenitors where mass transfer begins from a giant donor star and might extend to other SD systems. Not only is the amount of hydrogen left in such a system below the current detection limit, but the donor star is typically orders of magnitude smaller than its Roche lobe by the point when an SD SN Ia occurs, in which case attempts to observe collisions between SN shocks and giant donor stars seem unlikely to succeed. We consider the constraints on this model from the circumstellar structures seen in spectra of SN 2006X and suggest a novel explanation for the origin of this material.

  18. Neutronization During Carbon Simmering In Type Ia Supernova Progenitors

    NASA Astrophysics Data System (ADS)

    Martínez-Rodríguez, Héctor; Piro, Anthony L.; Schwab, Josiah; Badenes, Carles

    2016-07-01

    When a Type Ia supernova (SN Ia) progenitor first ignites carbon in its core, it undergoes ˜103–104 years of convective burning prior to the onset of thermonuclear runaway. This carbon simmering phase is important for setting the thermal profile and composition of the white dwarf. Using the MESA stellar evolution code, we follow this convective burning and examine the production of neutron-rich isotopes. The neutron content of the SN fuel has important consequences for the ensuing nucleosynthesis, and in particular, for the production of secondary Fe-peak nuclei like Mn and stable Ni. These elements have been observed in the X-ray spectra of SN remnants like Tycho, Kepler, and 3C 397, and their yields can provide valuable insights into the physics of SNe Ia and the properties of their progenitors. We find that weak reactions during simmering can at most generate a neutron excess of ≈ 3 × 10‑4. This is ≈ 70% lower than that found in previous studies that do not take the full density and temperature profile of the simmering region into account. Our results imply that the progenitor metallicity is the main contributor to the neutron excess in SN Ia fuel for Z ≳ 1/3 Z ⊙. Alternatively, at lower metallicities, this neutron excess provides a floor that should be present in any centrally-ignited SN Ia scenario.

  19. Neutronization During Carbon Simmering In Type Ia Supernova Progenitors

    NASA Astrophysics Data System (ADS)

    Martínez-Rodríguez, Héctor; Piro, Anthony L.; Schwab, Josiah; Badenes, Carles

    2016-07-01

    When a Type Ia supernova (SN Ia) progenitor first ignites carbon in its core, it undergoes ∼103–104 years of convective burning prior to the onset of thermonuclear runaway. This carbon simmering phase is important for setting the thermal profile and composition of the white dwarf. Using the MESA stellar evolution code, we follow this convective burning and examine the production of neutron-rich isotopes. The neutron content of the SN fuel has important consequences for the ensuing nucleosynthesis, and in particular, for the production of secondary Fe-peak nuclei like Mn and stable Ni. These elements have been observed in the X-ray spectra of SN remnants like Tycho, Kepler, and 3C 397, and their yields can provide valuable insights into the physics of SNe Ia and the properties of their progenitors. We find that weak reactions during simmering can at most generate a neutron excess of ≈ 3 × 10‑4. This is ≈ 70% lower than that found in previous studies that do not take the full density and temperature profile of the simmering region into account. Our results imply that the progenitor metallicity is the main contributor to the neutron excess in SN Ia fuel for Z ≳ 1/3 Z ⊙. Alternatively, at lower metallicities, this neutron excess provides a floor that should be present in any centrally-ignited SN Ia scenario.

  20. TYPE Ia SUPERNOVAE STRONGLY INTERACTING WITH THEIR CIRCUMSTELLAR MEDIUM

    SciTech Connect

    Silverman, Jeffrey M.; Nugent, Peter E.; Gal-Yam, Avishay; Arcavi, Iair; Ben-Ami, Sagi; Sullivan, Mark; Howell, D. Andrew; Graham, Melissa L.; Filippenko, Alexei V.; Bloom, Joshua S.; Cenko, S. Bradley; Clubb, Kelsey I.; Cao, Yi; Horesh, Assaf; Kulkarni, Shrinivas R.; Chornock, Ryan; Foley, Ryan J.; Coil, Alison L.; Griffith, Christopher V.; Kasliwal, Mansi M.; and others

    2013-07-01

    Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe Ia) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia shows evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogen-rich CSM; we refer to them as SNe Ia-CSM. In the first systematic search for such systems, we have identified 16 SNe Ia-CSM, and here we present new spectra of 13 of them. Six SNe Ia-CSM have been well studied previously, three were previously known but are analyzed in depth for the first time here, and seven are new discoveries from the Palomar Transient Factory. The spectra of all SNe Ia-CSM are dominated by H{alpha} emission (with widths of {approx}2000 km s{sup -1}) and exhibit large H{alpha}/H{beta} intensity ratios (perhaps due to collisional excitation of hydrogen via the SN ejecta overtaking slower-moving CSM shells); moreover, they have an almost complete lack of He I emission. They also show possible evidence of dust formation through a decrease in the red wing of H{alpha} 75-100 days past maximum brightness, and nearly all SNe Ia-CSM exhibit strong Na I D absorption from the host galaxy. The absolute magnitudes (uncorrected for host-galaxy extinction) of SNe Ia-CSM are found to be -21.3 mag {<=} M{sub R} {<=} -19 mag, and they also seem to show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM are all late-type spirals similar to the Milky Way, or dwarf irregulars like the Large Magellanic Cloud, which implies that these objects come from a relatively young stellar population. This work represents the most detailed analysis of the SN Ia-CSM class to date.

  1. THE HUBBLE SPACE TELESCOPE CLUSTER SUPERNOVA SURVEY. VI. THE VOLUMETRIC TYPE Ia SUPERNOVA RATE

    SciTech Connect

    Barbary, K.; Amanullah, R.; Fakhouri, H. K.; Goldhaber, G.; Huang, X.; Aldering, G.; Dawson, K. S.; Hsiao, E.; Brodwin, M.; Connolly, N.; Doi, M.; Ihara, Y.; Eisenhardt, P.; Faccioli, L.; Goobar, A.; Fadeyev, V.; Fruchter, A. S.; Gilbank, D. G.; Gladders, M. D.; Hattori, T.; Collaboration: Supernova Cosmology Project; and others

    2012-01-20

    We present a measurement of the volumetric Type Ia supernova (SN Ia) rate out to z {approx_equal} 1.6 from the Hubble Space Telescope Cluster Supernova Survey. In observations spanning 189 orbits with the Advanced Camera for Surveys we discovered 29 SNe, of which approximately 20 are SNe Ia. Twelve of these SNe Ia are located in the foregrounds and backgrounds of the clusters targeted in the survey. Using these new data, we derive the volumetric SN Ia rate in four broad redshift bins, finding results consistent with previous measurements at z {approx}> 1 and strengthening the case for an SN Ia rate that is {approx}> 0.6 Multiplication-Sign 10{sup -4} h{sup 3}{sub 70} yr{sup -1} Mpc{sup -3} at z {approx} 1 and flattening out at higher redshift. We provide SN candidates and efficiency calculations in a form that makes it easy to rebin and combine these results with other measurements for increased statistics. Finally, we compare the assumptions about host-galaxy dust extinction used in different high-redshift rate measurements, finding that different assumptions may induce significant systematic differences between measurements.

  2. Measurements of the Rate of Type Ia Supernovae at Redshift z < ~0.3 from the SDSS-II Supernova Survey

    SciTech Connect

    Dilday, Benjamin; Smith, Mathew; Bassett, Bruce; Becker, Andrew; Bender, Ralf; Castander, Francisco; Cinabro, David; Filippenko, Alexei V.; Frieman, Joshua A.; Galbany, Lluis; Garnavich, Peter M.; /Notre Dame U. /Stockholm U., OKC /Stockholm U.

    2010-01-01

    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 {approx}< 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{sub -0.95}{sup +1.61}% 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{sub V} = (2.69{sub -0.30-0.01}{sup +0.34+0.21}) x 10{sup -5} SNe yr{sup -1} Mpc{sup -3} (H{sub 0}/(70 km s{sup -1} Mpc{sup -1})){sup 3} at a mean redshift of {approx} 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{sub V} (z) = A{sub p} x ((1+z)/(1+z{sub 0})){sup {nu}}, over the redshift range 0.0 < z < 0.3 with z{sub 0} = 0.21, results in A{sub p} = (3.43{sub -0.15}{sup +0.15}) x 10{sup -5} SNe yr{sup -1} Mpc{sup -3} (H{sub 0}/(70 km s{sup -1} Mpc{sup -1})){sup 3} and {nu} = 2.04{sub -0.89}{sup +0.90}.

  3. SN~2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-degenerate Binary Companion

    NASA Astrophysics Data System (ADS)

    Marion, G. H.; Brown, Peter J.; Vinkó, Jozsef; Silverman, Jeffrey M.; Sand, David J.; Challis, Peter; Kirshner, Robert P.; Wheeler, J. Craig; Berlind, Perry; Brown, Warren R.; Calkins, Michael L.; Camacho, Yssavo; Dhungana, Govinda; Foley, Ryan J.; Friedman, Andrew S.; Graham, Melissa L.; Howell, D. Andrew; Hsiao, Eric Y.; Irwin, Jonathan M.; Jha, Saurabh W.; Kehoe, Robert; Macri, Lucas M.; Maeda, Keiichi; Mandel, Kaisey; McCully, Curtis; Pandya, Viraj; Rines, Kenneth J.; Wilhelmy, Steven; Zheng, Weikang

    2016-04-01

    We report evidence for excess blue light from the Type Ia supernova (Sn Ia) SN 2012cg at 15 and 16 days before maximum B-band brightness. The emission is consistent with predictions for the impact of the supernova on a non-degenerate binary companion. This is the first evidence for emission from a companion to a normal SN Ia. Sixteen days before maximum light, the B-V color of SN 2012cg is 0.2 mag bluer than for other normal SN Ia. At later times, this supernova has a typical SN Ia light curve, with extinction-corrected {M}B=-19.62+/- 0.02 mag and {{Δ }}{m}15(B)=0.86+/- 0.02. Our data set is extensive, with photometry in seven filters from five independent sources. Early spectra also show the effects of blue light, and high-velocity features are observed at early times. Near maximum, the spectra are normal with a silicon velocity vSi = -10,500 km s-1. Comparing the early data with models by Kasen favors a main-sequence companion of about six solar masses. It is possible that many other SN Ia have main-sequence companions that have eluded detection because the emission from the impact is fleeting and faint.

  4. Light Curves of Supernovae

    NASA Astrophysics Data System (ADS)

    Spencer, Michelle; Joner, Michael; Laney, David; Stoker, Emily

    2012-10-01

    Photometric Data were secured for the supernovae 2010hh, 2011dh, 2011fe and 2012aw before the dates which each individual maxima occur. The data for all supernovae were secured using the 0.9-meter telescope at the BYU West Mountain Observatory in Utah. 2010hh data were secured during the summer 2010 over the months of August to October. 2011dh and 2011fe data were secured during the summer of 2011. 2012aw data were secured during the summer of 2012. The data exposures from 2010 were secured using standard B,V and R filters. The frames for 2011 were secured using B,V, R and I filters. The 2012 supernova frames were secured in B,V and R filters. Using the data I will compare and contrast these four different supernovae and discuss their possible uses for distance determinations for the host galaxies.

  5. THE DISCOVERY OF THE MOST DISTANT KNOWN TYPE Ia SUPERNOVA AT REDSHIFT 1.914

    SciTech Connect

    Jones, David O.; Rodney, Steven A.; Riess, Adam G.; Mobasher, Bahram; Dahlen, Tomas; Casertano, Stefano; Koekemoer, Anton; McCully, Curtis; Keeton, Charles R.; Patel, Brandon; Frederiksen, Teddy F.; Hjorth, Jens; Strolger, Louis-Gregory; Wiklind, Tommy G.; Challis, Peter; Hayden, Brian; Garnavich, Peter; Weiner, Benjamin J.; Filippenko, Alexei V.; and others

    2013-05-10

    We present the discovery of a Type Ia supernova (SN) at redshift z = 1.914 from the CANDELS multi-cycle treasury program on the Hubble Space Telescope (HST). This SN was discovered in the infrared using the Wide-Field Camera 3, and it is the highest-redshift Type Ia SN yet observed. We classify this object as a SN Ia by comparing its light curve and spectrum with those of a large sample of Type Ia and core-collapse SNe. Its apparent magnitude is consistent with that expected from the {Lambda}CDM concordance cosmology. We discuss the use of spectral evidence for classification of z > 1.5 SNe Ia using HST grism simulations, finding that spectral data alone can frequently rule out SNe II, but distinguishing between SNe Ia and SNe Ib/c can require prohibitively long exposures. In such cases, a quantitative analysis of the light curve may be necessary for classification. Our photometric and spectroscopic classification methods can aid the determination of SN rates and cosmological parameters from the full high-redshift CANDELS SN sample.

  6. Understanding the Progenitor Systems, Explosion Mechanisms, and Cosmological Utility of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Foley, Ryan

    2014-10-01

    Despite using Type Ia supernovae (SN Ia) to precisely measure cosmological parameters, we still do not know basic facts about the progenitor systems and explosions. Theory suggests that SN Ia progenitor metallicity is correlated with its peak luminosity, but not its light-curve shape. As a result, this effect should lead to an increased Hubble scatter, reducing the precision with which we measure distances. If the average progenitor metallicity changes with redshift, cosmological measurements could be biased. Models also indicate that changing the progenitor metallicity will have little effect on the appearance of optical SN data, but significantly change UV spectra. These data can only be obtained with HST.We recently published the first detection of 2 SN Ia with different progenitor metallicities. These "twin" SN had nearly identical optical spectra and light-curve shapes, but different UV spectra and peak luminosities, consistent with the models. We now must increase the sample of SN Ia with UV spectral time series to investigate the impact of metallicity on SN properties. To do this, we plan to obtain UV spectral time series of 3 SN Ia, nearly doubling the sample. UV observations are critical to the understanding of SN Ia explosions and progenitors. This is our best opportunity to further our understanding of SN Ia while directly improving the utility of SN Ia for cosmology.Using parallel observations, we will obtain Cepheid distances to a subset of the SN for free, providing precise SN luminosities and a better measurement of the Hubble constant. The UV Initiative is an excellent opportunity for HST to address significant questions in SN physics and cosmology.

  7. Improving Cosmological Distance Measurements Using Twin Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Fakhouri, H. K.; Boone, K.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Barbary, K.; Baugh, D.; Bongard, S.; Buton, C.; Chen, J.; Childress, M.; Chotard, N.; Copin, Y.; Fagrelius, P.; Feindt, U.; Fleury, M.; Fouchez, D.; Gangler, E.; Hayden, B.; Kim, A. G.; Kowalski, M.; Leget, P.-F.; Lombardo, S.; Nordin, J.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Ren, J.; Rigault, M.; Rubin, D.; Runge, K.; Saunders, C.; Scalzo, R.; Smadja, G.; Sofiatti, C.; Strovink, M.; Suzuki, N.; Tao, C.; Thomas, R. C.; Weaver, B. A.; Nearby Supernova Factory, The

    2015-12-01

    We introduce a method for identifying “twin” Type Ia supernovae (SNe Ia) and using them to improve distance measurements. This novel approach to SN Ia standardization is made possible by spectrophotometric time series observations from the Nearby Supernova Factory (SNfactory). We begin with a well-measured set of SNe, find pairs whose spectra match well across the entire optical window, and then test whether this leads to a smaller dispersion in their absolute brightnesses. This analysis is completed in a blinded fashion, ensuring that decisions made in implementing the method do not inadvertently bias the result. We find that pairs of SNe with more closely matched spectra indeed have reduced brightness dispersion. We are able to standardize this initial set of SNfactory SNe to 0.083 ± 0.012 mag, implying a dispersion of 0.072 ± 0.010 mag in the absence of peculiar velocities. We estimate that with larger numbers of comparison SNe, e.g., using the final SNfactory spectrophotometric data set as a reference, this method will be capable of standardizing high-redshift SNe to within 0.06-0.07 mag. These results imply that at least 3/4 of the variance in Hubble residuals in current SN cosmology analyses is due to previously unaccounted-for astrophysical differences among the SNe.

  8. TYPE Ia SUPERNOVA COLORS AND EJECTA VELOCITIES: HIERARCHICAL BAYESIAN REGRESSION WITH NON-GAUSSIAN DISTRIBUTIONS

    SciTech Connect

    Mandel, Kaisey S.; Kirshner, Robert P.; Foley, Ryan J.

    2014-12-20

    We investigate the statistical dependence of the peak intrinsic colors of Type Ia supernovae (SNe Ia) on their expansion velocities at maximum light, measured from the Si II λ6355 spectral feature. We construct a new hierarchical Bayesian regression model, accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust, and implement a Gibbs sampler and deviance information criteria to estimate the correlation. The method is applied to the apparent colors from BVRI light curves and Si II velocity data for 79 nearby SNe Ia. The apparent color distributions of high-velocity (HV) and normal velocity (NV) supernovae exhibit significant discrepancies for B – V and B – R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B band, rather than dust reddening. The mean intrinsic B – V and B – R color differences between HV and NV groups are 0.06 ± 0.02 and 0.09 ± 0.02 mag, respectively. A linear model finds significant slopes of –0.021 ± 0.006 and –0.030 ± 0.009 mag (10{sup 3} km s{sup –1}){sup –1} for intrinsic B – V and B – R colors versus velocity, respectively. Because the ejecta velocity distribution is skewed toward high velocities, these effects imply non-Gaussian intrinsic color distributions with skewness up to +0.3. Accounting for the intrinsic-color-velocity correlation results in corrections to A{sub V} extinction estimates as large as –0.12 mag for HV SNe Ia and +0.06 mag for NV events. Velocity measurements from SN Ia spectra have the potential to diminish systematic errors from the confounding of intrinsic colors and dust reddening affecting supernova distances.

  9. Quantitative comparison between type Ia supernova spectra at low and high redshifts: a case study

    NASA Astrophysics Data System (ADS)

    Garavini, G.; Folatelli, G.; Nobili, S.; Aldering, G.; Amanullah, R.; Antilogus, P.; Astier, P.; Blanc, G.; Bronder, T.; Burns, M. S.; Conley, A.; Deustua, S. E.; Doi, M.; Fabbro, S.; Fadeyev, V.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hook, I.; Howell, D. A.; Kashikawa, N.; Kim, A. G.; Kowalski, M.; Kuznetsova, N.; Lee, B. C.; Lidman, C.; Mendez, J.; Morokuma, T.; Motohara, K.; Nugent, P. E.; Pain, R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Sainton, G.; Schahmaneche, K.; Smith, E.; Spadafora, A. L.; Stanishev, V.; Thomas, R. C.; Walton, N. A.; Wang, L.; Wood-Vasey, W. M.; Yasuda, N.

    2007-08-01

    We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 ≤ z ≤ 0.912) SNe Ia observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of the absorption minimum in Ca ii H&K, we show that the spectra of the high-redshift SNe Ia are quantitatively similar to spectra of nearby SNe Ia (z < 0.15). One supernova in our high redshift sample, SN 2002fd at z = 0.279, is found to have spectral characteristics that are associated with peculiar SN 1991T/SN 1999aa-like supernovae.

  10. Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study

    SciTech Connect

    Supernova Cosmology Project; Nugent, Peter E; Garavini, G.; Folatelli, G.; Nobili, S.; Aldering, G.; Amanullah, R.; Antilogus, P.; Astier, P.; Blanc, G.; Bronder, J.; Burns, M.S.; Conley, A.; Deustua, S. E.; Doi, M.; Fabbro, S.; Fadeyev, V.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hook, I.; Howell, D. A.; Kashikawa, N.; Kim, A. G.; Kowalski, M.; Kuznetsova, N.; Lee, B. C.; Lidman, C.; Mendez, J.; Morokuma, T.; Motohara, K.; Nugent, P. E.; Pain, R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Sainton, G.; Schahmaneche, K.; Smith, E.; Spadafora, A. L.; Stanishev, V.; Thomas, R. C.; Walton, N. A.; Wang, L.; Wood-Vasey, W. M.; Yasuda, N.

    2008-03-24

    We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 = z = 0.912) SNe Ia observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of theabsorption minimum in Ca ii H&K, we show that the spectra of the high-redshift SNe Ia are quantitatively similar to spectra of nearby SNe Ia (z< 0.15). One supernova in our high redshift sample, SN 2002fd at z = 0.279, is found to have spectral characteristics that are associated with peculiar SN 1991T/SN 1999aa-like supernovae.

  11. Observation of cosmological time dilation using type Ia supernovae as clocks

    SciTech Connect

    Goldhaber, G., FNAL

    1998-09-01

    This work is based on the first results from a systematic search for high redshift Type Ia supernovae. Using filters in the R-band we discovered seven such SNe, with redshift z = 0.3-0.5, before or at maximum light. Type Ia SNe are known to be a homogeneous group of SNe, to first order, with very similar light curves, spectra and peak luminosities. In this talk we report that the light curves we observe are all broadened (time dilated) as expected from the expanding universe hypothesis. Small variations from the expected 1 + z broadening of the light curve widths can be attributed to a width-brightness correlation that has been observed for nearby SNe (z < 0.1). We show in this talk the first clear observation of the cosmological time dilation for macroscopic objects.

  12. Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra

    NASA Astrophysics Data System (ADS)

    Childress, Michael J.; Hillier, D. John; Seitenzahl, Ivo; Sullivan, Mark; Maguire, Kate; Taubenberger, Stefan; Scalzo, Richard; Ruiter, Ashley; Blagorodnova, Nadejda; Camacho, Yssavo; Castillo, Jayden; Elias-Rosa, Nancy; Fraser, Morgan; Gal-Yam, Avishay; Graham, Melissa; Howell, D. Andrew; Inserra, Cosimo; Jha, Saurabh W.; Kumar, Sahana; Mazzali, Paolo A.; McCully, Curtis; Morales-Garoffolo, Antonia; Pandya, Viraj; Polshaw, Joe; Schmidt, Brian; Smartt, Stephen; Smith, Ken W.; Sollerman, Jesper; Spyromilio, Jason; Tucker, Brad; Valenti, Stefano; Walton, Nicholas; Wolf, Christian; Yaron, Ofer; Young, D. R.; Yuan, Fang; Zhang, Bonnie

    2015-12-01

    The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of 56Ni to 56Co at early times, and the decay of 56Co to 56Fe from ˜60 d after explosion. We examine the evolution of the [Co III] λ5893 emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of 56Co as a function of time. This result indicates both efficient local energy deposition from positrons produced in 56Co decay and long-term stability of the ionization state of the nebula. We compile SN Ia nebular spectra from the literature and present 21 new late-phase spectra of 7 SNe Ia, including SN 2014J. From these we measure the flux in the [Co III] λ5893 line and remove its well-behaved time dependence to infer the initial mass of 56Ni (MNi) produced in the explosion. We then examine 56Ni yields for different SN Ia ejected masses (Mej - calculated using the relation between light-curve width and ejected mass) and find that the 56Ni masses of SNe Ia fall into two regimes: for narrow light curves (low stretch s ˜ 0.7-0.9), MNi is clustered near MNi ≈ 0.4 M⊙ and shows a shallow increase as Mej increases from ˜1 to 1.4 M⊙; at high stretch, Mej clusters at the Chandrasekhar mass (1.4 M⊙) while MNi spans a broad range from 0.6 to 1.2 M⊙. This could constitute evidence for two distinct SN Ia explosion mechanisms.

  13. A SEARCH FOR NEW CANDIDATE SUPER-CHANDRASEKHAR-MASS TYPE Ia SUPERNOVAE IN THE NEARBY SUPERNOVA FACTORY DATA SET

    SciTech Connect

    Scalzo, R.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Hsiao, E. Y.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Chotard, N.; Copin, Y.; Gangler, E.; Nugent, P.; Collaboration: Nearby Supernova Factory; and others

    2012-09-20

    We present optical photometry and spectroscopy of five Type Ia supernovae discovered by the Nearby Supernova Factory selected to be spectroscopic analogs of the candidate super-Chandrasekhar-mass events SN 2003fg and SN 2007if. Their spectra are characterized by hot, highly ionized photospheres near maximum light, for which SN 1991T supplies the best phase coverage among available close spectral templates. Like SN 2007if, these supernovae are overluminous (-19.5 < M{sub V} < -20) and the velocity of the Si II {lambda}6355 absorption minimum is consistent with being constant in time from phases as early as a week before, and up to two weeks after, B-band maximum light. We interpret the velocity plateaus as evidence for a reverse-shock shell in the ejecta formed by interaction at early times with a compact envelope of surrounding material, as might be expected for SNe resulting from the mergers of two white dwarfs. We use the bolometric light curves and line velocity evolution of these SNe to estimate important parameters of the progenitor systems, including {sup 56}Ni mass, total progenitor mass, and masses of shells and surrounding carbon/oxygen envelopes. We find that the reconstructed total progenitor mass distribution of the events (including SN 2007if) is bounded from below by the Chandrasekhar mass, with SN 2007if being the most massive. We discuss the relationship of these events to the emerging class of super-Chandrasekhar-mass SNe Ia, estimate the relative rates, compare the mass distribution to that expected for double-degenerate SN Ia progenitors from population synthesis, and consider implications for future cosmological Hubble diagrams.

  14. A Search for New Candidate Super-Chandrasekhar-mass Type Ia Supernovae in the Nearby Supernova Factory Data Set

    NASA Astrophysics Data System (ADS)

    Scalzo, R.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Gangler, E.; Guy, J.; Hsiao, E. Y.; Kerschhaggl, M.; Kowalski, M.; Nugent, P.; Paech, K.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.; Wu, C.; Nearby Supernova Factory, The

    2012-09-01

    We present optical photometry and spectroscopy of five Type Ia supernovae discovered by the Nearby Supernova Factory selected to be spectroscopic analogs of the candidate super-Chandrasekhar-mass events SN 2003fg and SN 2007if. Their spectra are characterized by hot, highly ionized photospheres near maximum light, for which SN 1991T supplies the best phase coverage among available close spectral templates. Like SN 2007if, these supernovae are overluminous (-19.5 < MV < -20) and the velocity of the Si II λ6355 absorption minimum is consistent with being constant in time from phases as early as a week before, and up to two weeks after, B-band maximum light. We interpret the velocity plateaus as evidence for a reverse-shock shell in the ejecta formed by interaction at early times with a compact envelope of surrounding material, as might be expected for SNe resulting from the mergers of two white dwarfs. We use the bolometric light curves and line velocity evolution of these SNe to estimate important parameters of the progenitor systems, including 56Ni mass, total progenitor mass, and masses of shells and surrounding carbon/oxygen envelopes. We find that the reconstructed total progenitor mass distribution of the events (including SN 2007if) is bounded from below by the Chandrasekhar mass, with SN 2007if being the most massive. We discuss the relationship of these events to the emerging class of super-Chandrasekhar-mass SNe Ia, estimate the relative rates, compare the mass distribution to that expected for double-degenerate SN Ia progenitors from population synthesis, and consider implications for future cosmological Hubble diagrams.

  15. The Host Galaxies of Type Ia Supernovae Discovered by the Palomar Transient Factory

    NASA Technical Reports Server (NTRS)

    Pan, Y.-C.; Sullivan, M.; McGuire, K.; Hook, I. M.; Nugent, P. E.; Howell, D. A.; Arcavi, I.; Botyanszki, J.; Cenko, Stephen Bradley; DeRose, J.

    2013-01-01

    We present spectroscopic observations of the host galaxies of 82 low-redshift type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF). We determine star-formation rates, gas-phase stellar metallicities, and stellar masses and ages of these objects. As expected, strong correlations between the SN Ia light-curve width (stretch) and the host age mass metallicity are found: fainter, faster-declining events tend to be hosted by older massive metal-rich galaxies. There is some evidence that redder SNe Ia explode in higher metallicity galaxies, but we found no relation between the SN colour and host galaxy extinction based on the Balmer decrement, suggesting that the colour variation of these SNe does not primarily arise from this source. SNe Ia in higher-mass metallicity galaxies also appear brighter after stretch colour corrections than their counterparts in lower mass hosts, and the stronger correlation is with gas-phase metallicity suggesting this may be the more important variable. We also compared the host stellar mass distribution to that in galaxy targeted SN surveys and the high-redshift untargeted Supernova Legacy Survey (SNLS). SNLS has many more low mass galaxies, while the targeted searches have fewer. This can be explained by an evolution in the galaxy stellar mass function, coupled with a SN delay-time distribution proportional to t1. Finally, we found no significant difference in the mass--metallicity relation of our SN Ia hosts compared to field galaxies, suggesting any metallicity effect on the SN Ia rate is small.

  16. Verifying the Cosmological Utility of Type Ia Supernovae: Implications of a Dispersion in the Ultraviolet Spectra

    SciTech Connect

    Nugent, Peter E; Ellis, R.S.; Sullivan, M.; Nugent, P.E.; Howell, D.A.; Gal-Yam, A.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R.; Conley, A.; Fouchez, D.; Guy, J.; Hardin, D.; Hook, I.; Pain, R.; Perrett, K.; Pritchet, C.J.; Regnault, N.

    2008-02-28

    We analyze the mean rest-frame ultraviolet (UV) spectrum of Type Ia Supernovae (SNe) and its dispersion using high signal-to-noise ratio Keck-I/LRIS-B spectroscopy for a sample of 36 events at intermediate redshift (z=0.5) discovered by the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We introduce a new method for removing host galaxy contamination in our spectra, exploiting the comprehensive photometric coverage of the SNLS SNe and their host galaxies, thereby providing the first quantitative view of the UV spectral properties of a large sample of distant SNe Ia. Although the mean SN Ia spectrum has not evolved significantly over the past 40percent of cosmic history, precise evolutionary constraints are limited by the absence of a comparable sample of high-quality local spectra. The mean UV spectrum of our z~;;=0.5 SNe Ia and its dispersion is tabulated for use in future applications. Within the high-redshift sample, we discover significant UV spectral variations and exclude dust extinction as the primary cause by examining trends with the optical SN color. Although progenitor metallicity may drive some of these trends, the variations we see are much larger than predicted in recent models and do not follow expected patterns. An interesting new result is a variation seen in the wavelength of selected UV features with phase. We also demonstrate systematic differences in the SN Ia spectral features with SN light curve width in both the UV and the optical. We show that these intrinsic variations could represent a statistical limitation in the future use of high-redshift SNe Ia for precision cosmology. We conclude that further detailed studies are needed, both locally and at moderate redshift where the rest-frame UV can be studied precisely, in order that future missions can confidently be planned to fully exploit SNe Ia as cosmological probes.

  17. The Diffuse Gamma-Ray Background from Type Ia Supernovae

    NASA Technical Reports Server (NTRS)

    Lien, Amy; Fields, Brian D.

    2012-01-01

    The origin of the diffuse extragalactic gamma-ray background (EGB) has been intensively studied but remains unsettled. Current popular source candidates include unresolved star-forming galaxies, starburst galaxies, and blazars. In this paper we calculate the EGB contribution from the interactions of cosmic rays accelerated by Type Ia supernovae, extending earlier work which only included core-collapse supernovae. We consider Type Ia events in star-forming galaxies, but also in quiescent galaxies that lack star formation. In the case of star-forming galaxies, consistently including Type Ia events makes little change to the star-forming EGB prediction, so long as both supernova types have the same cosmic-ray acceleration efficiencies in star-forming galaxies. Thus our updated EGB estimate continues to show that star-forming galaxies can represent a substantial portion of the signal measured by Fermi. In the case of quiescent galaxies, conversely, we find a wide range of possibilities for the EGB contribution. The dominant uncertainty we investigated comes from the mass in hot gas in these objects, which provides targets for cosmic rays: total gas masses are as yet poorly known, particularly at larger radii. Additionally, the EGB estimation is very sensitive to the cosmic-ray acceleration efficiency and confinement, especially in quiescent galaxies. In the most optimistic allowed scenarios, quiescent galaxies can be an important source of the EGB. In this case, star-forming galaxies and quiescent galaxies together will dominate the EGB and leave little room for other contributions. If other sources, such as blazars, are found to have important contributions to the EGB, then either the gas mass or cosmic-ray content of quiescent galaxies must be significantly lower than in their star-forming counterparts. In any case, improved Fermi EGB measurements will provide important constraints on hot gas and cosmic rays in quiescent galaxies.

  18. Simulating the Double-Degenerate Channel for Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Jumper, Kevin; Fisher, R. T.

    2013-01-01

    Type Ia Supernovae (SNe Ia) are the thermonuclear explosions of white dwarfs, and are of fundamental importance to the study of many phenomena, including the expansion of the universe and dark energy. For many years, it was suspected that that SNe Ia occur in binary systems, but the identity of the white dwarf’s companion could not be determined. A leading hypothesis, the single-degenerate (SD) channel, suggests that the companion is either on the main sequence or a red giant, and that the white dwarf accretes matter off of its companion until it nears the Chandrasekhar limit of 1.4 solar masses, causing the white dwarf to detonate shortly thereafter. Another hypothesis, the double-degenerate (DD) channel, proposes that both stars in the system are white dwarfs and that they merge together, resulting in a central, rapidly spinning white dwarf, surrounded by a thick disk of remnant material. Precisely how this triggers a detonation remains unclear; early spherically-symmetric models by Nomoto et al. indicated that merged white dwarfs would collapse to neutron stars instead of producing supernovae. Recent observations of two supernovae discovered last year by the Palomar Transient Factory (PTF), SN 2011 fe and SN PTF11k, have provided evidence that suggests that both the SD and DD channels coexist in nature. Consequently, it is important to develop simulations that can resolve the mystery of the DD channel’s detonation mechanism. To this end, we use a smoothed-particle hydrodynamics (SPH) code, GADGET-1, to model the rotating flows characteristic of merged DD systems and study how they evolve with time.

  19. Turbulence-Flame Interactions in Type Ia Supernovae

    SciTech Connect

    Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720; Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064; Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794; Aspden, Andrew J; Aspden, Andrew J.; Bell, John B.; Day, Marc S.; Woosley, Stan E.; Zingale, Mike

    2008-05-27

    The large range of time and length scales involved in type Ia supernovae (SN Ia) requires the use of flame models. As a prelude to exploring various options for flame models, we consider, in this paper, high-resolution three-dimensional simulations of the small-scale dynamics of nuclear flames in the supernova environment in which the details of the flame structure are fully resolved. The range of densities examined, 1 to 8 x 107 g cm-3, spans the transition from the laminar flamelet regime to the distributed burning regime where small scale turbulence disrupts the flame. The use of a low Mach number algorithm facilitates the accurate resolution of the thermal structure of the flame and the inviscid turbulent kinetic energy cascade, while implicitly incorporating kinetic energy dissipation at the grid-scale cutoff. For an assumed background of isotropic Kolmogorov turbulence with an energy characteristic of SN Ia, we find a transition density between 1 and 3 x 107 g cm-3 where the nature of the burning changes ualitatively. By 1 x 107 g cm-3, energy diffusion by conduction and radiation is exceeded, on the flame scale, by turbulent advection. As a result, the effective Lewis Number approaches unity. That is, the flame resembles a laminar flame, but is turbulently broadened with an effective diffusion coefficient, D_T \\sim u' l, where u' is the turbulent intensity and l is the integral scale. For the larger integral scales characteristic of a real supernova, the flame structure is predicted to become complex and unsteady. Implications for a possible transition to detonation are discussed.

  20. Type Ia supernovae from merging white dwarfs. II. Post-merger detonations

    SciTech Connect

    Raskin, Cody; Kasen, Daniel; Moll, Rainer; Woosley, Stan; Schwab, Josiah

    2014-06-10

    Merging carbon-oxygen (CO) white dwarfs are a promising progenitor system for Type Ia supernovae (SNe Ia), but the underlying physics and timing of the detonation are still debated. If an explosion occurs after the secondary star is fully disrupted, the exploding primary will expand into a dense CO medium that may still have a disk-like structure. This interaction will decelerate and distort the ejecta. Here we carry out multidimensional simulations of 'tamped' SN Ia models, using both particle and grid-based codes to study the merger and explosion dynamics and a radiative transfer code to calculate synthetic spectra and light curves. We find that post-merger explosions exhibit an hourglass-shaped asymmetry, leading to strong variations in the light curves with viewing angle. The two most important factors affecting the outcome are the scale height of the disk, which depends sensitively on the binary mass ratio, and the total {sup 56}Ni yield, which is governed by the central density of the remnant core. The synthetic broadband light curves rise and decline very slowly, and the spectra generally look peculiar, with weak features from intermediate mass elements but relatively strong carbon absorption. We also consider the effects of the viscous evolution of the remnant and show that a longer time delay between merger and explosion probably leads to larger {sup 56}Ni yields and more symmetrical remnants. We discuss the relevance of this class of aspherical 'tamped' SN Ia for explaining the class of 'super-Chandrasekhar' SN Ia.

  1. Nucleosynthesis in type Ia supernovae driven by asymmetric thermonuclear ignition

    SciTech Connect

    Maeda, Keiichi

    2012-11-12

    Type Ia Supernovae (SNe Ia) are believed to be thermonuclear explosions of a white dwarf. They can be used as mature cosmological standardized candles, leading to the discovery of the accelerating expansion of the Universe. However, the explosion mechanism has not yet been fully clarified. In this paper, we first present nucleosynthetic features of a leading explosion scenario, namely a delayed-detonation scenario. Based on this, we propose a new and strong observational constraint on the explosion mechanism through emission lines from neutron-rich Fe-peaks. Especially, we show that an asymmetry in the explosion is likely a generic feature. We further argue that the diversity arising from various viewing angles can be an origin of observational diversities of SNe Ia seen in their spectral features (suspected possible biases in cosmology) and colors (related to the extinction estimate in cosmology). Using these new insights could open up a possibility of using SNe Ia as more precise distance indicators than currently employed.

  2. Recurrent novae as progenitors of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Kato, Mariko; Hachisu, Izumi

    2012-09-01

    Recurrent novae are binaries harboring a very massive white dwarf (WD), as massive as the Chandrasekhar mass, because of their short recurrence periods of nova outbursts of 10--100 years. Thus, recurrent novae are considered as candidates of progenitors of Type Ia supernovae (SNe~Ia). In fact, the SN~Ia PTF~11kx showed evidence that its progenitor is a symbiotic recurrent nova. The binary parameters of recurrent novae have been well determined, especially for the ones with frequent outbursts, U Sco and RS Oph, which provide useful information on the elementary processes in binary evolution toward SNe~Ia. Therefore we use them as testbeds for binary evolution models. For example, the original double degenerate (DD) scenario cannot reproduce RS Oph type recurrent novae, whereas the new single degenerate (SD) scenario proposed by Hachisu et al. (1999) naturally can. We review main differences between the SD and DD scenarios, especially for their basic processes of binary evolution. We also discuss observational support for each physical process. The original DD scenario is based on the physics in 1980s, whereas the SD scenario on more recent physics including the new opacity, mass-growth efficiency of WDs, and optically thick winds developed in nova outbursts.

  3. Lensed Type Ia supernovae as probes of cluster mass models

    NASA Astrophysics Data System (ADS)

    Nordin, J.; Rubin, D.; Richard, J.; Rykoff, E.; Aldering, G.; Amanullah, R.; Atek, H.; Barbary, K.; Deustua, S.; Fakhouri, H. K.; Fruchter, A. S.; Goobar, A.; Hook, I.; Hsiao, E. Y.; Huang, X.; Kneib, J.-P.; Lidman, C.; Meyers, J.; Perlmutter, S.; Saunders, C.; Spadafora, A. L.; Suzuki, N.; Supernova Cosmology Project

    2014-05-01

    Using three magnified Type Ia supernovae (SNe Ia) detected behind CLASH (Cluster Lensing and Supernovae with Hubble) clusters, we perform a first pilot study to see whether standardizable candles can be used to calibrate cluster mass maps created from strong lensing observations. Such calibrations will be crucial when next-generation Hubble Space Telescope cluster surveys (e.g. Frontier) provide magnification maps that will, in turn, form the basis for the exploration of the high-redshift Universe. We classify SNe using combined photometric and spectroscopic observations, finding two of the three to be clearly of Type Ia and the third probable. The SNe exhibit significant amplification, up to a factor of 1.7 at ˜5σ significance (SN-L2). We conducted this as a blind study to avoid fine-tuning of parameters, finding a mean amplification difference between SNe and the cluster lensing models of 0.09 ± 0.09stat ± 0.05sys mag. This impressive agreement suggests no tension between cluster mass models and high-redshift-standardized SNe Ia. However, the measured statistical dispersion of σμ = 0.21 mag appeared large compared to the dispersion expected based on statistical uncertainties (0.14). Further work with the SN and cluster lensing models, post-unblinding, reduced the measured dispersion to σμ = 0.12. An explicit choice should thus be made as to whether SNe are used unblinded to improve the model, or blinded to test the model. As the lensed SN samples grow larger, this technique will allow improved constraints on assumptions regarding e.g. the structure of the dark matter halo.

  4. Restframe I-band Hubble diagram for type Ia supernovae up toredshift z ~; 0.5

    SciTech Connect

    Nobili, S.; Amanullah, R.; Garavini, G.; Goobar, A.; Lidman, C.; Stanishev, V.; Aldering, G.; Antilogus, P.; Astier, P.; Burns, M.S.; Conley, A.; Deustua, S.E.; Ellis, R.; Fabbro, S.; Fadeyev, V.; Folatelli,G.; Gibbons, R.; Goldhaber, G.; Groom, D.E.; Hook, I.; Howell, D.A.; Kim,A.G.; Knop, R.A.; Nugent, P.E.; Pain, R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Sainton, G.; Schahmaneche, K.; Smith, E.; Spadafora, A.L.; Thomas, R.C.; Wang, L.

    2005-04-01

    We present a novel technique for fitting rest frame I-bandlight curves on a data set of 42 type Ia supernovae (SNe Ia). Using the result of the fit, we construct a Hubble diagram with 26 SNe from the subset at 0.01 < z < 0.1. Adding two SNe at z {approx} 0.5 yields results consistent with a flat Lambda-dominated ''concordance universe'' (OmegaM,Omega Lambda) = (0.25, 0.75). For one of these, SN 2000fr, new near infrared data are presented. The high redshift supernova NIR data are also used to test for systematic effects in the use of SNe Ia as distance estimators. A flat, Lambda = 0, universe where the faintness of supernovae at z {approx} 0.5 is due to grey dust homogeneously distributed in the intergalactic medium is disfavored based on the high-z Hubble diagram using this small data-set. However, the uncertainties are large and no firm conclusion may be drawn. We explore the possibility of setting limits on intergalactic dust based on B - I and B - V color measurements, and conclude that about 20 well measured SNe are needed to give statistically significant results. We also show that the high redshift restframe I-band data points are better fit by light curve templates that show a prominent second peak, suggesting that they are not intrinsically underluminous.

  5. Early-type Host Galaxies of Type Ia Supernovae. I. Evidence for Downsizing

    NASA Astrophysics Data System (ADS)

    Kang, Yijung; Kim, Young-Lo; Lim, Dongwook; Chung, Chul; Lee, Young-Wook

    2016-03-01

    Type Ia supernova (SN Ia) cosmology provides the most direct evidence for the presence of dark energy. This result is based on the assumption that the lookback time evolution of SN Ia luminosity, after light curve corrections, would be negligible. Recent studies show, however, that the Hubble residual (HR) of SN Ia is correlated with the mass and morphology of host galaxies, implying the possible dependence of SN Ia luminosity on host galaxy properties. In order to investigate this more directly, we have initiated a spectroscopic survey for early-type host galaxies, for which population age and metallicity can be more reliably determined from the absorption lines. In this first paper of the series, we present here the results from high signal-to-noise ratio (≳100 per pixel) spectra for 27 nearby host galaxies in the southern hemisphere. For the first time in host galaxy studies, we find a significant (∼3.9σ) correlation between host galaxy mass (velocity dispersion) and population age, which is consistent with the “downsizing” trend among non-host early-type galaxies. This result is rather insensitive to the choice of population synthesis models. Since we find no correlation with metallicity, our result suggests that stellar population age is mainly responsible for the relation between host mass and HR. If confirmed, this would imply that the luminosity evolution plays a major role in the systematic uncertainties of SN Ia cosmology.

  6. Rates and Properties of Type Ia Supernovae as a Function of Mass and Star Formation in Their Host Galaxies

    NASA Astrophysics Data System (ADS)

    Sullivan, M.; Le Borgne, D.; Pritchet, C. J.; Hodsman, A.; Neill, J. D.; Howell, D. A.; Carlberg, R. G.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K.; Regnault, N.; Rich, J.; Taillet, R.; Baumont, S.; Bronder, J.; Ellis, R. S.; Filiol, M.; Lusset, V.; Perlmutter, S.; Ripoche, P.; Tao, C.

    2006-09-01

    We show that Type Ia supernovae (SNe Ia) are formed within both very young and old stellar populations, with observed rates that depend on the stellar mass and mean star formation rates (SFRs) of their host galaxies. Models in which the SN Ia rate depends solely on host galaxy stellar mass are ruled out with >99% confidence. Our analysis is based on 100 spectroscopically confirmed SNe Ia, plus 24 photometrically classified events, all from the Supernova Legacy Survey (SNLS) and distributed over 0.2Ia host galaxies by fitting their broadband spectral energy distributions with the galaxy spectral synthesis code PÉGASE.2. We show that the SN Ia rate per unit mass is proportional to the specific SFR of the parent galaxies-more vigorously star-forming galaxies host more SNe Ia per unit stellar mass, broadly equivalent to the trend of increasing SN Ia rate in later type galaxies seen in the local universe. Following earlier suggestions for a simple ``two-component'' model approximating the SN Ia rate, we find bivariate linear dependencies of the SN Ia rate on both the stellar masses and the mean SFRs of the host systems. We find that the SN Ia rate can be well represented as the sum of 5.3+/-1.1×10-14 SNe yr-1 Msolar-1 and 3.9+/-0.7×10-4 SNe yr-1 (Msolar yr-1)-1 of star formation. We also demonstrate a dependence of distant SN Ia light-curve shapes on star formation in the host galaxy, similar to trends observed locally. Passive galaxies, with no star formation, preferentially host faster declining/dimmer SNe Ia, while brighter events are found in systems with ongoing star formation.

  7. THE VERY YOUNG TYPE Ia SUPERNOVA 2013dy: DISCOVERY, AND STRONG CARBON ABSORPTION IN EARLY-TIME SPECTRA

    SciTech Connect

    Zheng, WeiKang; Filippenko, Alexei V.; Nugent, Peter E.; Graham, Melissa; Kelly, Patrick L.; Fox, Ori D.; Shivvers, Isaac; Clubb, Kelsey I.; Li, Weidong; Silverman, Jeffrey M.; Howie Marion, G.; Kasen, Daniel; Wang, Xiaofeng; Valenti, Stefano; Howell, D. Andrew; Ciabattari, Fabrizio; Cenko, S. Bradley; Balam, Dave; Hsiao, Eric; Sand, David; and others

    2013-11-20

    The Type Ia supernova (SN Ia) 2013dy in NGC 7250 (d ≈ 13.7 Mpc) was discovered by the Lick Observatory Supernova Search. Combined with a prediscovery detection by the Italian Supernova Search Project, we are able to constrain the first-light time of SN 2013dy to be only 0.10 ± 0.05 days (2.4 ± 1.2 hr) before the first detection. This makes SN 2013dy the earliest known detection of an SN Ia. We infer an upper limit on the radius of the progenitor star of R {sub 0} ≲ 0.25 R {sub ☉}, consistent with that of a white dwarf. The light curve exhibits a broken power law with exponents of 0.88 and then 1.80. A spectrum taken 1.63 days after first light reveals a C II absorption line comparable in strength to Si II. This is the strongest C II feature ever detected in a normal SN Ia, suggesting that the progenitor star had significant unburned material. The C II line in SN 2013dy weakens rapidly and is undetected in a spectrum 7 days later, indicating that C II is detectable for only a very short time in some SNe Ia. SN 2013dy reached a B-band maximum of M{sub B} = –18.72 ± 0.03 mag ∼17.7 days after first light.

  8. Unified One-Dimensional Simulations of Gamma-Ray Line Emission from Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Milne, P. A.; Hungerford, A. L.; Fryer, C. L.; Evans, T. M.; Urbatsch, T. J.; Boggs, S. E.; Isern, J.; Bravo, E.; Hirschmann, A.; Kumagai, S.; Pinto, P. A.; The, L.-S.

    2004-10-01

    The light curves of Type Ia supernovae (SNe Ia) are powered by gamma rays emitted by the decay of radioactive elements such as 56Ni and its decay products. These gamma rays are downscattered, absorbed, and eventually reprocessed into the optical emission that makes up the bulk of all SN observations. Detection of the gamma rays that escape the expanding star provide the only direct means to study this power source for SN Ia light curves. Unfortunately, disagreements between calculations for the gamma-ray lines have made it difficult to interpret any gamma-ray observations. Here we present a detailed comparison of the major gamma-ray line transport codes for a series of one-dimensional SN Ia models. Discrepancies in past results were due to errors in the codes, and the corrected versions of the seven different codes yield very similar results. This convergence of the simulation results allows us to infer more reliable information from the current set of gamma-ray observations of SNe Ia. The observations of SN 1986G, SN 1991T, and SN 1998bu are consistent with explosion models based on their classification: subluminous, superluminous, and normally luminous, respectively.

  9. Direct Numerical Simulations of Flame Instabilities in Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Zingale, M.; Bell, J. B.; Day, M. S.; Rendleman, C. A.; Woosley, S. E.

    2003-12-01

    Instabilities serve an important role in accelerating a thermonuclear flame in a white dwarf to a large fraction of the speed of sound (perhaps to a supersonic detonation), consuming the carbon/oxygen, and producing a Type Ia supernovae. The precise mechanism for this acceleration is not well understood, but large scale simulations show that a deflagration alone can unbind the star. We present fully resolved, multidimensional calculations of Rayleigh-Taylor unstable flames in conditions appropriate to the late stages of Type Ia SNe, using a low Mach number hydrodynamics code. At densities below 1.e7 g/cc, a fundamental change in the burning is observed, as the flame transitions from the wrinkled flame to the distributed burning regime. Significant acceleration is observed for all densities we study, limited only by the size of the domain we can address. We compare with corresponding simulations of the Landau-Darrieus instability. We discuss the physics of these instabilities on the small scales and the implications they have for large scale flame modeling and the possibility for deflagration to detonation transitions. Support for this work was provided by the DOE grant No. DE-FC02-01ER41176 to the Supernova Science Center/UCSC and the Applied Mathematics Program of the DOE Office of Mathematics, Information, and Computational Sciences under the U.S. Department of Energy under contract No. DE-AC03-76SF00098.

  10. Type Ia Supernovae: Explosion Models versus Observational Constraints

    NASA Astrophysics Data System (ADS)

    Branch, David

    2005-04-01

    To have confidence in using Type Ia supernovae (SNe Ia) to determine the expansion history of the universe, and thereby probe the nature of the dark energy, we must advance our understanding of SN Ia physics. In the standard model a carbon--oxygen white dwarf accretes matter from a companion star, approaches the Chandrasekhar mass, ignites carbon fusion, encounters a thermonuclear instability, and explodes completely. The final kinetic energy of the ejected matter is the energy released by fusion minus the white--dwarf binding energy. The kinetic energy inferred from observations indicates that practically the whole white dwarf undergoes fusion. The peak luminosity depends on the mass of freshly synthesized ^56Ni, which provides a delayed release of energy while decaying through ^56Co to stable ^56Fe. The observed SN Ia luminosity requires that nearly half of the mass is synthesized to ^56Ni. Spectroscopic observations indicate that the composition structure of the ejected matter is radially stratified, with a core of iron--group elements surrounded by lighter elements such as calcium, silicon, and oxygen. Spherically symmetric (1D) nuclear-hydrodynamical explosion models that meet these requirements have been calculated, by parameterizing the velocity of the burning front. In recent years more self--consistent 3D models have been calculated. Deflagration models, in which the burning front remains subsonic, undergo insufficient fusion and lack the stratified composition structure. Delayed--detonation models, which invoke a transition to supersonic front propagation, fare better, although it is not known whether the transition really can occur. I will discuss the status of explosion models versus observational constraints (mostly spectroscopic), and the challenging task of relating the various observational manifestations of SN Ia diversity to their physical causes.