Download or read book Analysis of Light Curves of Type Ia Supernovae written by Gertrud Contardo and published by . This book was released on 2001 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Observational Analysis of the Late Light Curves of Normal Type Ia Supernovae written by Jessica Crist Lair and published by . This book was released on 2006 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Rise and Fall of Type Ia Supernova Light Curves in the SDSS II Supernova Survey written by and published by . This book was released on 2010 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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} (almost equal to)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 sample.

Download or read book Astrophysik IV Sternsysteme Astrophysics IV Stellar Systems written by Frank K. Edmonson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 573 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Supernovae written by Athem W. Alsabti and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Functional Data Analysis written by James Ramsay and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 317 pages. Available in PDF, EPUB and Kindle. Book excerpt: Included here are expressions in the functional domain of such classics as linear regression, principal components analysis, linear modelling, and canonical correlation analysis, as well as specifically functional techniques such as curve registration and principal differential analysis. Data arising in real applications are used throughout for both motivation and illustration, showing how functional approaches allow us to see new things, especially by exploiting the smoothness of the processes generating the data. The data sets exemplify the wide scope of functional data analysis; they are drawn from growth analysis, meteorology, biomechanics, equine science, economics, and medicine. The book presents novel statistical technology while keeping the mathematical level widely accessible. It is designed to appeal to students, applied data analysts, and to experienced researchers; and as such is of value both within statistics and across a broad spectrum of other fields. Much of the material appears here for the first time.

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 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 Light Curves of Type Ia Supernovae written by Charles Hamilton Ford and published by . This book was released on 1992 with total page 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 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 Modeling Light Curves of Type Ia Supernovae written by Dennis Jack and published by . This book was released on 2009 with total page 98 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 Infrared Light Curves of Type Ia Supernovae written by Andrew Samuel Friedman and published by . This book was released on 2012 with total page 0 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 The Photometric Properties of Nearby Type Ia Supernovae written by Mohan Ganeshalingam and published by . This book was released on 2012 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: Type Ia supernovae (SNe Ia) are the final brilliant explosion of a carbon-oxygen white dwarf accreting mass from a companion star. At peak brightness, a SN Ia can outshine an entire galaxy of billions of stars. Most SNe Ia have a standardizable luminosity, ideal for use as an extragalactic distance indicator. Measurements of a large sample of SNe Ia over a range of distances enables the estimate of cosmological parameters to help determine the mass-energy content of the Universe (Riess et al. 1998; Perlmutter et al. 1999; Riess et al. 2004; Astier et al. 2006; Riess et al. 2007; Wood-Vasey et al. 2008; Kowalski et al. 2008; Hicken et al. 2009a; Amanullah et al. 2010; Sullivan et al. 2011a; Suzuki et al. 2012). The cosmological application of SNe Ia is predicated upon relationships between the intrinsic luminosity and light-curve properties. Despite the successful measurement of cosmological parameters using SNe Ia, our understanding of SNe Ia themselves is surprisingly lacking. The SN Ia progenitor system has never been directly observed, making it unclear how many different channels exist to make a SN Ia. The physical nature of the relationship between light-curve parameters and luminosity is also not well understood, and it remains to be seen whether other correlations exist to improve SN Ia distance estimates. The goal of this dissertation is to shed light on the physics of SNe Ia and search for new correlations to improve distance estimates to SNe Ia by analyzing a large sample of well-observed, high-quality SN Ia light curves. I have collected, reduced, and analyzed optical photometric data for 165 nearby SNe Ia as part of the Lick Observatory Supernova Search (LOSS). These data represent a significant contribution to the existing sample of nearby SN Ia light curves. After giving a general overview of SNe Ia in Chapter 1, I present the methods used to obtain and reduce the LOSS data in Chapter 2. In Chapter 3, I use the LOSS data in an analysis of the earliest photometry epochs to understand the explosion physics governing the initial rise of the SN Ia light curve. These early data points also provide a means of testing models to constrain the nature of the binary companion star. I do not find evidence for interaction between SN ejecta and a companion star, ruling out theories requiring a red giant as a companion in most cases. In Chapter 4, I combine the data presented in this thesis with other samples in the literature to place constraints on cosmological parameters. I reject a non-accelerating Universe with 99.999% confidence. In Chapter 5, I present a study of an individual peculiar SN Ia that is unlike any previously published object, bucking the relationships normally observed in SNe Ia. Studying extreme SNe Ia may provide insights into understanding the physics of normal SNe Ia.

Download or read book Spectral Observations and Analyses of Low Redshift Type Ia Supernovae written by Jeffrey Michael Silverman and published by . This book was released on 2011 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt: The explosive deaths of stars, known as a supernovae (SNe), have been critical to our understanding of the Universe for centuries. From the first evidence of a changing Universe beyond the Moon (Brahe1573) to the first evidence of the accelerating expansion of the Universe (Riess et al. 1998; Perlmutter et al. 1999), SNe - and often a specific subclass of SNe called Type Ia SNe (SNe Ia) - have been integral to astronomical research. An introduction to SNe, their importance in astronomy, and how we observe them is given in Chapter 1. How SNe Ia explode, what progenitor systems give rise to them, and how different initial conditions affect the observed outcomes of these objects are understood only at a relatively basic level. In other words, a detailed understanding of the physics behind SNe Ia is still lacking. One way astronomers can begin to solve these problems, and others involving SNe Ia, is to obtain and analyze a large, self-consistent dataset of SN Ia observations. This is the goal of the Berkeley SN Ia Program (BSNIP) which comprises the majority of this Thesis. In the second Chapter, I present the full BSNIP sample which consists of 1298 low-redshift (z greater than or equal to 0.2) optical spectra of 582 SNe Ia observed from 1989 through the end of 2008. Many of the SNe have well-calibrated light curves with measured distances as well as spectra which have been corrected for host-galaxy contamination. Most of the data were obtained using the Kast double spectrograph mounted on the Shane 3 m telescope at Lick Observatory with typical wavelength coverage of 3300-10400 A, which is significantly larger than that of most previously published SN Ia spectral datasets. I also present the BSNIP observing and reduction procedures used during the two decades over which the data were collected. In addition, I describe our spectral classification scheme (using the SuperNova IDentification code, SNID; Blondin & Tonry 2007), utilizing my newly constructed set of SNID spectral templates. These templates allow me to accurately spectroscopically classify the entire BSNIP dataset, and by doing so I am able to reclassify a handful of objects as bona fide SNe Ia and a few other objects as members of some of the peculiar SN Ia subtypes. In fact, the BSNIP dataset includes spectra of nearly 90 spectroscopically peculiar SNe Ia. I also present spectroscopic host-galaxy redshifts of some SNe Ia where these values were previously unknown. The sheer size of the BSNIP dataset and the consistency of the observation and reduction methods makes this sample unique among all other published SN Ia datasets and is complementary in many ways to the large, low-redshift SN Ia spectra presented by Matheson et al. 2008 and Blondin et al. 2011. I present measurements of spectral features of 432 low-redshift (z z x1 and c) and spectral measurements to calculate distance moduli. The residuals from these models is then compared to the standard model which only uses light-curve stretch and color. The pEW of Si II lamda 4000 is found to be a good indicator of light-curve width and the pEWs of the Mg II and Fe II complexes are relatively good proxies for color. However, a distance model only using these spectroscopic measurements performs worse than the standard model which uses only light-curve parameters. When using a distance model which combines the ratio of fluxes near 3̃600 A and 4̃300 A with both x1 and c, the Hubble residuals are decreased by 12%, which is found to be significant at the 2.4 omega level. The weighted root-mean square of the residuals using this model is 0.130 plus or minus 0.019 mag (as compared to 0.146 plus or minus 0.019 mag when using the same sample with the standard model). This Hubble diagram fit has one of the smallest scatters ever published and at the highest significance ever seen in such a study. Finally, these results are discussed with regard to how they can improve the cosmological accuracy of future, large-scale SN Ia surveys. Finally, I conclude this Thesis with an in-depth study of a quite peculiar SN Ia, not included in the BSNIP sample. Chapter 5 presents and analyzes optical photometry and spectra of the extremely luminous and slowly evolving Type Ia SN 2009dc, and offers evidence that it is a super-Chandrasekhar mass (SC) SN Ia and thus had a SC white dwarf (WD) progenitor. Optical spectra of SN 2007if, a similar object, are also shown. SN 2009dc had one of the most slowly evolving light curves ever observed for a SN Ia, with a rise time of 2̃3 d and delta m15(B) = 0.72 mag. I calculate a lower limit to the peak bolometric luminosity of 2̃.4x1043 erg s-1, though the actual value is likely almost 40% larger. Optical spectra of SNe 2009dc and 2007if obtained near maximum brightness exhibit strong C II features (indicative of a significant amount of unburned material), and the post-maximum spectra are dominated by iron-group elements. All of the spectra of SNe 2009dc and 2007if also show low expansion velocities. However, I see no strong evidence in SN 2009dc for a velocity "plateau" near maximum light like the one seen in SN 2007if (Scalzo et al. 2010). The high luminosity and low expansion velocities of SN 2009dc lead to a derived WD progenitor mass of more than 2 MSun and a 56Ni mass of about 1.4-1.7 MSun. I propose that the host galaxy of SN 2009dc underwent a gravitational interaction with a neighboring galaxy in the relatively recent past. This may have led to a sudden burst of star formation which could have produced the SC WD progenitor of SN 2009dc and likely turned the neighboring galaxy into a "post-starburst galaxy." No published model seems to match the extreme values observed in SN 2009dc, but simulations do show that such massive progenitors can exist (likely as a result of the merger of two WDs) and can possibly explode as SC SNe Ia.