Download or read book Parameter Sensitivity of Synthetic Spectra and Light Curves of Type Ia Supernovae written by Ernst Rolf Lexen and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Parameter Sensitivity of Synthetic Spectra and Light Curves of Type Ia Supernovae written by and published by . This book was released on 2014 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthetic Spectra and Light Curves of Type Ia Supernovae written by Markus Kromer and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NLTE Synthetic Spectra and Light Curves of Type Ia Supernovae written by Eric J. Lentz and published by . This book was released on 2000 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cosmological Parameter Uncertainties from SALT II Type Ia Supernova Light Curve Models written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Improving the Precision of Type I A Supernova Cosmology written by Jing Lu and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Type Ia supernovae (SNe Ia) mark the beginning and the end of stellar evolution. They are one of the most powerful cosmological probes in our universe thanks to their high intrinsic luminosities and standardizable properties. In the 1990s, the observation of SNe Ia led to the discovery of the accelerating cosmic expansion that was awarded the Nobel Prize in 2011. Despite decades of advancements, the exact details of progenitor systems (id est what exploded), explosion mechanisms (id est, how they exploded), and evolution effect (id est are the nearby population the same as those in the early universe?) are still not fully understood yet. With more advanced observation surveys forthcoming in the near future, such as those on board the Vera C. Rubin Observatory and the Nancy Grace Roman Space Telescope, the systematic uncertainties of SNe Ia observations will continue to dominate the error budget of their distance measurements. This dissertation is motivated to improve the precision of SN~Ia cosmology by understanding the physics and diversity and SNe Ia, as well as improving the astronomical tools needed for cosmological purposes. Photometric and spectroscopic observational studies of the first homogenous sample of the peculiar 03fg-like SNe Ia obtained by the Carnegie Supernovae Project (CSP) are conducted to investigate the physics of SNe Ia. 03fg-like events are usually more luminous than the normal SNe Ia and exhibit peculiar light-curve shapes in the redder filters, such as the weak or missing secondary maxima and the delayed peak time in iYJH bands. Spectroscopically, 03fg-like SN Ia show peculiar features in both optical and near-infrared (NIR) regions, such as the stronger C, slower Si, and the lack of the H-band break. One of the most extreme objects within this subgroup, ASASSN-15hy, is used for the case study of an envelope model that could potentially explain all 03fg-like SNe~Ia. It is found that a core degenerate scenario, an explosion of a degenerate white dwarf core inside a nondegenerate envelope, with a transition from deflagration to detonation can explain the observed peculiar properties. In the case of ASASSN-15hy, the low metallicity of the progenitor is a key aspect of the model explanation. In fact, a low-metallicity host environment is a shared preference among these 03fg-like SNe~Ia. Such host environment is more common in the early universe, which brings up the concern that 03fg-like SNe~Ia may be a problem for high-redshift SN~Ia cosmology due to detection bias and potential evolution preference. Therefore, more detailed observational and theoretical studies of these events are strongly recommended. Another main focus of this dissertation is on the development of a new NIR spectral template of SNe Ia that captures the feature variations that are correlated with the light-curve shapes. Compared to optical observations, NIR observations of SN Ia are less sensitive to dust and have more uniform peak luminosities, which are beneficial for cosmological purposes. A spectral template is usually needed to fit the light curves of SNe Ia accurately in order to estimate the distance. However, the NIR part of the existing spectral templates lacks an accurate description of the intrinsic spectral variations. Using the largest and most homogeneous collection of NIR spectra of SNe Ia to date collected by CSP-II, we are able to explore the NIR spectral diversity of SNe Ia and build a new NIR spectra template. Principal component analysis and Gaussian process regression are used for the template construction, which reduces data dimensionality and models the parameter dependence, respectively. Using the new template reduces the systematic uncertainties in K-corrections by ~90% compared to those from the Hsiao template. Furthermore, this template can serve as the baseline spectral energy distribution for various light-curve fitters and can identify peculiar spectral features that might point to compelling physics. The NIR spectra data and template presented in this work will substantially improve future SN Ia cosmological experiments, for both nearby and distant samples.

Download or read book Type Ia Supernovae written by Jens C. Niemeyer and published by Cambridge University Press. This book was released on 2000-05 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unique and wide-ranging review of one of the most dramatic research results in astronomy in recent decades.

Download or read book Type Ia Supernova Hubble Residuals and Host Galaxy Properties written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Statistical Properties and Synthetic Spectra of Type Ia Supernovae written by Douglas L. Miller and published by . This book was released on 1994 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Type Ia Supernova Evolution and Dark Energy written by Ryan Joseph Foley and published by . This book was released on 2008 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constraining Type Ia Supernovae Progenitor Parameters Via Light Curves written by Benjamin Sadler and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: I study thermonuclear explosions of White Dwarf (WD) stars, or so-called Type Ia supernovae (SNe Ia). A WD is the final stage of stellar evolution of a star with an initial mass of less than 8 Solar masses, and the thermonuclear explosion occurs either when the WD is in a close binary system where mass overflows from a companion star in a red-giant or asymptotic-branch giant phase, or when two WDs merge. SNe Ia are as bright as their entire host galaxy, which allows their use as long-range cosmic beacons. Although their maximum brightness may vary by a factor of 20, an empirical correlation between their primary parameters of light curve (LC) shape and their intrinsic brightness allows us to account for the majority of this dispersion, with a residual uncertainty of roughly 20%. This calibration has led to their use as standardizable candles, which led to the discovery of the dark energy. Higher precision is needed to determine the nature of the dark energy, however, and to accomplish this we turn to secondary parameters of LC variation. I have devised a general scheme and developed a code to analyze large sets of LC data for these secondary parameter variations which is based on a combination of theoretical model template fitting and Principal Component Analysis. Novel methods for finding statistical trends in sparsely-sampled and non-coincidental light curve data are explored and utilized. In practice, data sets for different supernovae are inhomogeneous in time, time coverage and accuracy, but I have developed a method to remap these inhomogeneous data sets of large numbers of individual objects to a homogeneous data set centered in time and magnitude space from which we can obtain the external, primary, and secondary LC parameters of individual objects. The set of external parameters of a given SN include the time of its maximum light in various bands, its distance modulus, the extinction along the light path, and redshift corrections (K-corrections) due to cosmic expansion. I investigate the intrinsic primary parameter variation of SNe Ia via template fitting, and then probe the secondary LC variations using monochromatic differential analysis in the (UBV) bands. We use photometry from 25 SNe Ia which were recently and precisely observed by the Carnegie Supernova Project to analyze the presence of theoretical model-based differential LC signatures of Main-Sequence mass variation of the progenitor stars when they formed, central density variation of the WD at the time of the explosion, and metallicity Z variation the in the progenitors. The light curves in the V band are found to provide the highest accuracy in determining the distance modulus, K-corrections, extinction, main-sequence mass and central density of the WD progenitor, and also the V-band LCs are insensitive to metallicity. Moreover, the V-band appears to be the band which is most stable for differential creation due to the stability of the differentials with respect to uncertainties in the SNe pairs' primary parameters. The B-band's larger K-correction uncertainties and dependence on progenitor metallicity and primary parameter uncertainties discourages its use in secondary parameter differential analysis. As with B, the U-band also suffers large uncertainties in extinction and K-corrections, but this band is a good indicator of metallicity, because the effects of metallicity variation on differential LCs are larger by an order of magnitude than the Main-Sequence mass and central density effects combined. Our sample includes three SN1991T-like objects, but we find no evidence of secondary parameter variation among them, and conclude that this class of object may be identified by its primary LC parameter as well as its lack of secondary parameter features. Accounting for these secondary parameters reduces the residuals in the fiducial LC fits from 0.2 magnitude to approximately 0.02 magnitude, a requirement for high-precision cosmology based on SNe Ia. I also reconstruct the distributions of Main-Sequence mass, central density, and metallicity for the progenitors of the 25 SNe in our sample. I find that most SNe in our sample originate from stars close to the upper limit of the range of possible Main-Sequence masses, indicating that most SNe Ia explode relatively soon after the progenitor star's formation. However, the reconstructed progenitor mass distribution displays a long tail down to lower-mass objects of about 1.5 Solar masses. The central density secondary parameter distribution is much flatter, and shows SNe originate from WD progenitors of a wide range of central densities, from as low as 1.5E9 grams per cubic centimeter, and up to the limit of accretion-induced collapse, suggesting that some potential SNe Ia progenitors become neutron stars instead. Although our sample size is small, all SN1991bg-like objects in it come from progenitors with low reconstructed central density and metallicity secondary parameters. Because SN1991bg-like objects are only found in local samples and not in high-redshift searches, our findings suggest that these progenitor systems are formed at high redshifts but exhibit long delay times before the explosion.

Download or read book The Effects of Metallicity on the Brightness of Type Ia Supernovae written by Kimberly L. Dupczak and published by . This book was released on 2008 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermonuclear Supernovae written by P. Ruiz-Lapuente and published by Springer Science & Business Media. This book was released on 1997 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt: All theoretical and observational topics relevant to the understanding of the thermonuclear (Type Ia) supernova phenomenon are thoroughly and consistently reviewed by a panel including the foremost experts in the field. The book covers all aspects, ranging from the observations of SNe Ia at all stages and all wavelengths to the 2D and 3D modelling of thermonuclear flames in very dense plasmas. Scenarios for close binary evolution leading to SNe Ia are discussed. Particular emphasis is placed on the homogeneity vs. diversity of SNe Ia and on their use as standard candles to measure cosmological parameters. The book reflects the recent and very significant progress made in both the modelling of the explosions and in the observational field.

Download or read book Multi faceted Investigation of the Supernova Ia Progenitor Problem written by Epson Thiago Masikiv Heringer and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Type Ia supernovae are generally agreed to arise from thermonuclear explosions of carbon-oxygen white dwarfs, which are led to explode via interaction with a companion star in a binary system. The actual path to explosion, however, remains uncertain, with numerous plausible parent systems and explosion mechanisms suggested. Observationally, Type Ia supernovae have multiple subclasses, distinguished by their light curves and spectra. This raises the question of whether these differences reflect multiple mechanisms occurring in nature or, instead, that explosions can be described by variations of a few physical properties. In this thesis, I use a spectral modeling package to investigate whether the spectra of events of distinct subclasses can be understood as part of a spectral sequence, where one parameter is varied at a time. I find that a single ejecta structure is sufficient to provide reasonable fits for spectra that are prototypical of subluminous and normal events. These spectra can be obtained provided that the luminosity (and thus temperature) of the ejecta are adjusted appropriately. Using a similar method, I also study the distribution of unburned material in SN 2011fe, finding a relatively large range of solutions, which does not rule out the predictions of most physical models. Lastly, I investigate the time-dependent rate of supernovae resulting from a burst of star formation. This analysis can, in principle, discriminate among proposed evolutionary paths, because it is sensitive to the nature of the companion star. By modeling the rates as a power-law, I find a normalization constant that indicates that field and cluster galaxies may be explained by the same distribution, contrary to previous results. In addition, I also provide a state-of-the-art measurement of the slope of this distribution, finding that is intermediate between the various predictions and does not yet constrain the evolutionary path leading to Type Ia supernovae.

Download or read book The Diversity of Variations in the Spectra of Type Ia Supernovae written by Andrew James Wagers and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Type Ia supernovae (SNe Ia) are currently the best probe of the expansion history of the universe. Their usefulness is due chiefly to their uniformity between supernovae (SNe). However, there are some slight variations amongst SNe that have yet to be understood and accounted for. The goal of this work is to uncover relationships between the spectral features and the light curve decline rate, [delta]m15. Wavelet decomposition has been used to develop a new spectral index to measure spectral line strengths independent of the continuum and easily corrected for noise. This new method yields consistent results without the arbitrary uncertainties introduced by current methods and is particularly useful for spectra which do not have a clearly defined continuum. These techniques are applied to SN Ia spectra and correlations are found between the spectral features and light curve decline rate. The wavelet spectral indexes are used to measure the evolution of spectral features which are characterized by 3 or 4 parameters for the most complicated evolution. The three absorption features studied here are associated with sulfur and silicon and all show a transition in strength between 1 to 2 weeks after B-band maximum. Pearson correlation coefficients between spectral features and [delta]m15 are found to be significant within a week of maximum brightness and 3 to 4 weeks post-maximum. These correlations are used to determine the principal components at each epoch among the set of SN spectra in this work. The variation contained in the first principal component (PC1) is found to be greater than 60% to 70% for most epochs and reaching as high as 80% to 90% for epochs with the highest correlations. The same first principal component can be used to relate spectral feature strengths to the decline rate. These relations were used to estimate a SN light curve decline rate from a set of spectra taken over the course of the explosion, from a single spectrum, or from even a single spectral feature. These relationships could be used for future surveys to estimate spectral characteristics from light curve data, such as photometric redshift.

Download or read book Timescale Stretch Parameterization of Type Ia Supernova B band Light Curves written by and published by . This book was released on 2001 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Statistical Equations for Determining Parameters for Type II Plateau Supernova Light Curves written by Tricia Ann Johnson and published by . This book was released on 2005 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: