Download or read book Light Curves of Type Ia Supernovae and Preliminary Cosmological Constraints from the ESSENCE Survey written by Gautham Siddharth Narayan and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A New Approach for Obtaining Cosmological Constraints from Type Ia Supernovae Using Approximate Bayesian Computation written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmological parameter estimation techniques that robustly account for systematic measurement uncertainties will be crucial for the next generation of cosmological surveys. We present a new analysis method, superABC, for obtaining cosmological constraints from Type Ia supernova (SN Ia) light curves using Approximate Bayesian Computation (ABC) without any likelihood assumptions. The ABC method works by using a forward model simulation of the data where systematic uncertainties can be simulated and marginalized over. A key feature of the method presented here is the use of two distinct metrics, the `Tripp' and `Light Curve' metrics, which allow us to compare the simulated data to the observed data set. The Tripp metric takes as input the parameters of models fit to each light curve with the SALT-II method, whereas the Light Curve metric uses the measured fluxes directly without model fitting. We apply the superABC sampler to a simulated data set of $\sim$1000 SNe corresponding to the first season of the Dark Energy Survey Supernova Program. Varying $\Omega_m, w_0, \alpha$ and $\beta$ and a magnitude offset parameter, with no systematics we obtain $\Delta(w_0) = w_0^{\rm true} - w_0^{\rm best \, fit} = -0.036\pm0.109$ (a $\sim11$% 1$\sigma$ uncertainty) using the Tripp metric and $\Delta(w_0) = -0.055\pm0.068$ (a $\sim7$% 1$\sigma$ uncertainty) using the Light Curve metric. Including 1% calibration uncertainties in four passbands, adding 4 more parameters, we obtain $\Delta(w_0) = -0.062\pm0.132$ (a $\sim14$% 1$\sigma$ uncertainty) using the Tripp metric. Overall we find a $17$% increase in the uncertainty on $w_0$ with systematics compared to without. We contrast this with a MCMC approach where systematic effects are approximately included. We find that the MCMC method slightly underestimates the impact of calibration uncertainties for this simulated data set.
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 In Pursuit of Dark Energy written by Bradley Elton Tucker and published by . This book was released on 2013 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Equation of State SuperNova trace Cosmic Expansion (ESSENCE) was a 6 year survey which discovered and followed 228 type Ia supernova (SN Ia). The primary goal of ESSENCE was to characterize the dark energy equation-of-state, w. However, due to limitations in the knowledge of the SN Ia progenitor system and systematic errors related to influences of the host galaxies on SN Ia distances and the photometric calibrations of the survey, the measurements are only accurate to approximately 10%. Combining the 228 SN Ia light-curves with published data, we used a set of 695 SN Ia to search for progenitor signatures in SN Ia light-curves SN Ia. Kasen 2010 predicted that the companion star in a SN Ia would create a hole in the ejecta, allowing heated emission to escape, producing a strong signature in the early phases of a SN Ia light-curve. Using Monte-Carlo simulations, we examine the 695 SN Ia light-curves, searching for the peak flux in the ultra-violet (UV) and blue filters, expected from a red giant companion. Using both the frequency of these progenitor scenarios and viewing angles of the shock break-out, 4-5 detections are predicted. Our analysis yields zero detections, with a 98.2% confidence. We explain that the SN Ia scenario involving accretion from a red giant onto a white dwarf can not make up a significant fraction of the SN Ia population and better models are needed. Also using the ESSENCE survey, we develop a new method for determining the Spectral Energy Distribution (SED) and rest-frame magnitudes of the host galaxies from the UV to the infrared (IR) and use empirical relations to derive galaxy properties. We also calculate the normalized separation of the SN Ia from the center of the host galaxy. We find a substantial amount of UV emission in our passive galaxies, suggesting star-formation in these galaxies. Additionally we find an approximately 4 sigma correlation of the rest-frame Far UV (FUV) - V host galaxy color and distance residuals from best fitting cosmology (Hubble residual) when the sample is divided by host galaxy type. Lastly, we find SN Ia greater than 2 effective radii occur in low-extinction environments, producing a uniform sample of SN Ia for cosmological measurements. SN Ia at these distances have noticeable offsets in SN color and Hubble residual from the entire sample, suggesting improper SN Ia light-curve fitting, potentially biasing SN Ia distance measurements. Finally, we discuss improvements in the photometric calibration of the SN Ia photometry to reduce the systematic errors in distance measurements. We produced a photometrically flat image with less than 1% illumination gradient across the images. We also detail our automated procedure for correcting the flux of the SN Ia in a given aperture. These two improvements, along with a few other implementations, produce SN Ia photometry with approximately 1% accuracy. We compare our SN Ia photometry and light-curves to that of Wood-Vasey et al. 2007 illustrating the full extent of our improvements.
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 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 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 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 Aleksej M. Chochlov and published by . This book was released on 1991 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Type Ia Supernovae written by Brandon Patel and published by . This book was released on 2015 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 $sim 1.0 pm 0.2$ mag brighter than field SNe~Ia at a similar redshift and ascribe this to gravitational lens magnification. Similarly, SN CLN12Did is $sim 0.2 pm 0.2$ 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 ef{c4} 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 in the chapter. With nearly 1000 SNe~Ia usable for cosmology, we are currently systematics, not statistics, limited for constraining cosmology. MLCS3 will provide more accurate distance measurements for the SNe~Ia using a variety of improvements that have been suggested in the literature.
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 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 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 written by and published by . This book was released on 2001 with total page 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''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.
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 Lightcurves of Type Ia Supernovae from Near the Time of Explosion written by and published by . This book was released on 2006 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a set of 11 type Ia supernova (SN Ia) lightcurves with dense, pre-maximum sampling. These supernovae (SNe), in galaxies behind the Large Magellanic Cloud (LMC), were discovered by the SuperMACHO survey. The SNe span a redshift range of z = 0.11-0.35. Our lightcurves contain some of the earliest pre-maximum observations of SNe Ia to date. We also give a functional model that describes the SN Ia lightcurve shape (in our V R-band). Our function uses the ''expanding fireball'' model of Goldhaber et al. (1998) to describe the rising lightcurve immediately after explosion but constrains it to smoothly join the remainder of the lightcurve. We fit this model to a composite observed V R-band lightcurve of three SNe between redshifts of 0.135 to 0.165. These SNe have not been K-corrected or adjusted to account for reddening. In this redshift range, the observed V R-band most closely matches the rest frame V-band. Using the best fit to our functional description of the lightcurve, we find the time between explosion and observed V R-band maximum to be 19.2 ± 1.3-1.6 ± 0.07(red.) rest-frame days for a SN Ia with a V R-band [Delta]m10 of 0.52. For the redshifts sampled, the observed V R-band time-of-maximum brightness should be the same as the rest-frame V -band maximum to within 1.1 rest-frame days.
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 Rates and Progenitors of Type Ia Supernovae written by and published by . This book was released on 2004 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 analyzing the true sensitivity of a multi-epoch supernova search and finds a Type Ia supernova rate from z (almost equal to) 0.01-0.1 of r{sub V} = 4.26{sub -1.93 -0.10}{sup +1.39 +0.10} h3 x 10−4 SNe Ia/yr/Mpc3 from a preliminary analysis of a subsample of the SNfactory prototype search. Several unusual supernovae were found in the course of the SNfactory prototype search. One in particular, SN 2002ic, was the first SN Ia to exhibit convincing evidence for a circumstellar medium and offers valuable insight into the progenitors of Type Ia supernovae.
