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 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 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 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 Low Mass SN Ia and the Late Light Curve written by Stirling A. Colgate and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Low Mass SN Ia and the Late Light Curve written by and published by . This book was released on 1995 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: The late bolometric light curves of type Ia supernovae, when measured accurately over several years, show an exponential decay with a 56d half-life over a drop in luminosity of 8 magnitudes (10 half-lives). The late-time light curve is thought to be governed by the decay of Co56, whose 77d half-life must then be modified to account for the observed decay time. Two mechanisms, both relying upon the positron fraction of the Co56 decay, have been proposed to explain this modification. One explanation requires a large amount of emission at infra-red wavelengths where it would not be detected. The other explanation has proposed a progressive transparency or leakage of the high energy positrons (Colgate, Petschek and Kriese, 1980). For the positrons to leak out of the expanding nebula at the required rate necessary to produce the modified 56d exponential, the mass of the ejecta from a one foe (1051 erg in kinetic energy) explosion must be small, M{sub ejec} = 0.4M{sub {circle_dot}} with M{sub ejec} (proportional to) KE{sup 0.5}. Thus, in this leakage explanation, any reasonable estimate of the total energy of the explosion requires that the ejected mass be very much less than the Chandrasekhar mass of 1.4M{sub {circle_dot}}. This is very difficult to explain with the ''canonical'' Chandrasekhar-mass thermonuclear explosion that disintegrates the original white dwarf star. This result leads us to pursue alternate mechanisms of type Ia supernovae. These mechanisms include sub-Chandrasekhar thermonuclear explosions and the accretion induced collapse of Chandrasekhar mass white dwarfs. We will summarize the advantages and disadvantages of both mechanisms with considerable detail spent on our new accretion induced collapse simulations. These mechanisms lead to lower Ni56 production and hence result in type Ia supernovae with luminosities decreased down to (approximately) 50% that predicted by the ''standard'' model.

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 Observation of Cosmological Time Dilation Using Type Ia Supernovae as Clocks written by and published by . This book was released on 1998 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

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 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 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.

Download or read book Statistical Mechanics written by R.K. Pathria and published by Elsevier. This book was released on 2017-02-21 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt: Statistical Mechanics discusses the fundamental concepts involved in understanding the physical properties of matter in bulk on the basis of the dynamical behavior of its microscopic constituents. The book emphasizes the equilibrium states of physical systems. The text first details the statistical basis of thermodynamics, and then proceeds to discussing the elements of ensemble theory. The next two chapters cover the canonical and grand canonical ensemble. Chapter 5 deals with the formulation of quantum statistics, while Chapter 6 talks about the theory of simple gases. Chapters 7 and 8 examine the ideal Bose and Fermi systems. In the next three chapters, the book covers the statistical mechanics of interacting systems, which includes the method of cluster expansions, pseudopotentials, and quantized fields. Chapter 12 discusses the theory of phase transitions, while Chapter 13 discusses fluctuations. The book will be of great use to researchers and practitioners from wide array of disciplines, such as physics, chemistry, and engineering.

Download or read book Four Papers by the Supernova Cosmology Project written by and published by . This book was released on 1995 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: The search for high-redshift Type Ia supernovae discovered, in its first years, a sample of seven supernovae. Using a b̀̀atch ̀̀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 s̀̀tandard clock ̀̀to study the cosmological parameters q0,?,?0, and H0. These four presentations discuss observation strategies and rates, analysis and calibration issues, the sources of measurement uncertainty, and the cosmological implications, including bounds on q0, of these first high-redshift supernovae from the ongoing search.

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 Supernova Explosions written by David Branch and published by Springer. This book was released on 2017-08-02 with total page 719 pages. Available in PDF, EPUB and Kindle. Book excerpt: Targeting advanced students of astronomy and physics, as well as astronomers and physicists contemplating research on supernovae or related fields, David Branch and J. Craig Wheeler offer a modern account of the nature, causes and consequences of supernovae, as well as of issues that remain to be resolved. Owing especially to (1) the appearance of supernova 1987A in the nearby Large Magellanic Cloud, (2) the spectacularly successful use of supernovae as distance indicators for cosmology, (3) the association of some supernovae with the enigmatic cosmic gamma-ray bursts, and (4) the discovery of a class of superluminous supernovae, the pace of supernova research has been increasing sharply. This monograph serves as a broad survey of modern supernova research and a guide to the current literature. The book’s emphasis is on the explosive phases of supernovae. Part 1 is devoted to a survey of the kinds of observations that inform us about supernovae, some basic interpretations of such data, and an overview of the evolution of stars that brings them to an explosive endpoint. Part 2 goes into more detail on core-collapse and superluminous events: which kinds of stars produce them, and how do they do it? Part 3 is concerned with the stellar progenitors and explosion mechanisms of thermonuclear (Type Ia) supernovae. Part 4 is about consequences of supernovae and some applications to astrophysics and cosmology. References are provided in sufficient number to help the reader enter the literature.