The intrinsic colors of Type Ia supernovae (SNe Ia) are important to understanding their use as cosmological standard candles. Understanding the effects of reddening and redshift on the observed colors are complicated and dependent on the intrinsic spectrum, the filter curves, and the wavelength dependence of reddening. We present ultraviolet and optical data of a growing sample of SNe Ia observed with the Ultraviolet/Optical Telescope on the Swift spacecraft and use this sample to re-examine the near-UV (NUV) colors of SNe Ia. We find that a small amount of reddening (E(B - V) = 0.2 mag) could account for the difference between groups designated as NUVblue and NUV-red, and a moderate amount of reddening (E(B - V) = 0.5 mag) could account for the whole NUVoptical differences. The reddening scenario, however, is inconsistent with the mid-UV colors and color evolution. The effect of redshift alone only accounts for part of the variation. Using a spectral template of SN2011fe, we can forward model the effects of redshift and reddening and directly compare those with the observed colors. We find that some SNe are consistent with reddened versions of SN2011fe, but most SNe Ia are much redder in the uvw1 - v color than SN2011fe reddened to the same b - v color. The absolute magnitudes show that two out of five NUV-blue SNe Ia are blue because their near-UV luminosity is high, and the other three are optically fainter. We also show that SN. 2011fe is not a "normal" SN Ia in the UV, but has colors placing it at the blue extreme of our sample.

We present a systematic study of mid-infrared emission from 141 nearby supernovae (SNe). observed with Spitzer/IRAC as part of the ongoing SPIRITS survey. We detect 8 Type Ia and 36 core-collapse SNe. All Type. Ia/Ibc SNe. become undetectable within three. years of explosion, whereas 22 +/- 11% of Type. II SNe. continue to be detected. Five Type. II SNe are detected even two decades after discovery (SN 1974E, 1979C, 1980K, 1986J, and 1993J). Warm dust luminosity, temperature, and a lower limit on mass are obtained by fitting the two IRAC bands, assuming an optically thin dust shell. We derive warm dust masses between 10(-6) and 10(-2) M-circle dot and dust color temperatures between 200 and 1280 K. This observed warm dust could be pre-existing or newly created, but in either case represents a lower limit to the dust mass because cooler dust may be present. We present three case studies of extreme SNe.. SN 2011ja (II-P) was over-luminous ([4.5] = -15.6 mag) at 900 days post explosion with increasing hot dust mass, suggesting either an episode of dust formation or intensifying circumstellar material (CSM) interactions heating up pre-existing dust. SN 2014bi (II-P) showed a factor of 10 decrease in dust mass over one month, suggesting either dust destruction or reduced dust heating. The IR luminosity of SN 2014C (Ib) stayed. constant over 800 days, possibly due to strong CSM interaction with an. H-rich shell, which is rare among stripped-envelope SNe. The observations suggest that this CSM shell originated from an LBV-like eruption roughly 100 years pre-explosion. The observed diversity demonstrates the power of mid-IR observations of a large sample of SNe.

The IceCube Neutrino Observatory consists of a lattice of 5160 photomultiplier tubes (PMTs)<p>which monitor one cubic kilometer of deep Antarctic ice at the geographic South Pole.<p>IceCube was primarily designed to detect neutrinos of energies greater than O(100 GeV).<p>Due to subfreezing ice temperatures, the photomultipliers' dark noise rates are particularly<p>low which enables IceCube to search for neutrinos from galactic supernovae by detecting<p>bursts of MeV neutrinos emitted during the core collapse and for several seconds following.<p>For that purpose, a dedicated online supernova DAQ system records the total number of hits<p>in the detector, without any further information from the PMTs, and generates supernova<p>candidate triggers in case of a significant detector rate enhancement. A new feature to the<p>standard DAQ, called HitSpooling, was implemented in IceCube during this thesis. The<p>HitSpooling system is implemented in the standard DAQ system and buffers the complete<p>raw data stream of the photomultipliers for several hours or days. By reading out time periods<p>of HitSpool data around supernova candidate triggers, generated by the online supernova<p>DAQ system, we overcome the limitations of the latter and have access to the entire information<p>of the detector in case of a supernova. Furthermore, HitSpool data is a powerful<p>source for studying and understanding the noise behavior of the detector as well as background<p>processes coming from atmospheric muons. The idea of HitSpooling was developed in the<p>scope of this thesis and is the basis of the work at hand. The developed interface between the<p>standard DAQ and the supernova DAQ system is presented. The correlated dark noise component<p>in optical modules of IceCube is quantified for the first time and possible explanations<p>are discussed. The possibility of identifying triggering and subthreshold atmospheric muons<p>in HitSpool data and subtracting them from a possible supernova signal is analyzed. Furthermore,<p>the conversion from HitSpool data to supernova DAQ type data was developed<p>which allows for a comparison of both data types with respect to lightcurves and significances<p>of selected supernova candidate triggers. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22249号 / 理博第4563号 / 新制||理||1655(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 前田 啓一, 講師 LEE Shiu Hang, 教授 長田 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Polarization is detected at early times for all types of supernovae, indicating that all such systems are, or quickly become, asymmetric. Spectropolarimetric observations also show that the asymmetry varies in both magnitude and orientation for different elements in the ejecta. One explanation for these observations is that local chemical inhomogeneities (called clumps) exist in the ejecta above the region where the continuum forms. To examine the effects of clumpiness on observations, I will present results of a comparison between a fast, flexible, approximate semi-analytic code for modeling polarized line radiative transfer within three-dimensional inhomogeneous rapidly expanding atmospheres; and VLT spectropolarimetric observations of SN2006X.

This thesis presents a new method to estimate the Apparent Proper Motion (APM) vector and its uncertainty for supernova light echoes (LEs) and tests its usefulness in practice on LEs due to two old Galactic supernovae (SNe) - Cas A and Tycho. Ten instances of two-dimensional cross-correlation (2-D CC) of images containing light echoes at diferent epochs are employed to examine how well this new method works in practice. The images selected for this work originate from KPNO 4m Mosaic 1.1 images and were originally processed by the Pan-STARRS pipeline. All the APM estimates reported in this thesis are within 1sigma of estimates based on supernova distance and age provided reasonable inclinations are assumed. It was found that several factors tend to reduce the expected precision of this method and these include: 1) the existence of more than one LE feature for each epoch, 2) longer intervals between the two epochs lead to a bias, and 3) the existence of dust filaments at more than one depth along the line of sight. The results of three LE fields which were in common with the previous studies by Rest et al. in 2008 and 2011, were compared and a good agreement was found between them in difference-images with the same time interval. Since pixel values have a significant role in the introduced method, a control region is considered to eliminate the defect of the irrelevant residuals to the LE features. Hence, the introduced method was not straightforward. In addition, this method was not thoroughly manual independent, as the benefits of the visual measurement from the previous method reported by Rest et al. (2008) and (2011) were adopted for this method. However, compared to the previous manual technique, there were much less manual measurements were taken for the whole LE features in one frame. Considering all the challenges, the CC method is favourable as the APM vector uncertainty can be determined, which has not been achievable with previous method before. / Thesis / Master of Science (MSc)

No description available.

This thesis presents the spectroscopic observations of the Supernova Legacy Survey (SNLS) from the Gemini-North telescope from May 2006 – May 2008. During this time 68 of 95 targets were confirmed as Type Ia supernovae (SNe Ia) or classified as probable SNe Ia events. We use these objects and reanalyse other high-z spectra obtained as part of SNLS to search for signs of evolution in SNe Ia properties. To do this we use a multicolour method to remove host galaxy contamination from the high-z spectra and measure the equivalent widths of three spectral features in the rest-frame blue part of the spectrum: CaII H&K, SiII and Mg II. These are compared to a sample of low-z objects drawn from the literature. No evidence for evolution is found, but a change in the properties of the SiII feature is observed. This can be explained by changing supernova demographics, an outcome of the two-component progenitor model for SNe Ia. The utility of SNe Ia supernovae for cosmology is confirmed and the possible use of spectral features as alternative calibrators is investigated. The equivalenth width of the SiII feature is anticorrelated with light curve stretch and this is used to define a "spectral stretch" from the low-z sample, which is used to reduce the scatter in the low-z sample. This holds promise for improving the calibration of high-z SNe Ia, particularly if new facilities are used to provide higher-quality spectra.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 55-56. / by Willie R. Mackey. / Ph.D.

Feedback -- from stars and supermassive black holes -- is the bottleneck of our understanding on galaxy formation: it is likely to be critical, but neither the working mechanism nor the impact is clear. Supernovae (SNe), the dominant feedback force associated with stars, is the subject of this thesis. We use high-resolution, 3D hydrodynamic simulations to study: (i) how a SN blast wave imparts energy to a multiphase ISM; (ii) how multiple SNe regulate a multiphase ISM; (iii) how SNe drive galactic outflows. We focus on better understanding the physics, quantifying the impacts, and testing the simulations against observations.