Browsing by Author "Brown, Peter"

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Seeing Core-Collapse Supernovae in the Ultraviolet
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/230; NASA-Washington
Core-collapse supernovae are the catastrophic deaths of massive stars. Ultraviolet observations are needed to understand the energy of the explosion through the study of the bolometric light curves. Early-time ultraviolet observations constrain the size of the progenitor. Ultraviolet spectra can break the degeneracies between temperature/ionization, reddening, and metallicity which hinder our understanding of ultraviolet photometry. Optical observations of high-redshift supernovae probe rest-frame ultraviolet wavelengths, requiring space-based observations of nearby supernovae against which to compare. Ultraviolet observations of core-collapse supernovae can also help distinguish them from type Ia supernovae, enabling cleaner photometric type Ia supernova samples for cosmological measurements. The Ultraviolet/Optical Telescope (UVOT) on the Swift satellite has observed over two hundred core-collapse supernovae in the ultraviolet, including sixty-nine ultraviolet grism spectra of twenty core-collapse SNe. Additional ultraviolet spectra have been obtained by the International Ultraviolet Explorer, Hubble Space Telescope, and Galaxy Evolution Explorer. We propose a project to reduce the Swift grism spectra and combine with the other ultraviolet and groundbased optical/NIR spectra to create time-series bolometric spectra. We will use these bolometric spectra to better understand temperature, reddening, and metallicity and create bolometric light curves of these core collapse SNe. We will also use early time ultraviolet photometry and spectroscopy to constrain the progenitors of core collapse SNe. The ultraviolet observations fill a critical niche in our understanding of core collapse supernovae, and this program will enhance the scientific use of this important dataset from multiple space missions. Beyond core-collapse supernovae, the templates will allow studies of the dust properties around the progenitor systems (including the wavelength dependence of the extinction). The templates will improve the photometric classification and distance bias modeling for Type Ia supernova cosmology, while the extinction and temperature constraints will improve the use of type IIP supernovae as a distinct distance indicator on their own.
Seeing Core-Collapse Supernovae in the Ultraviolet
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/230; NASA-Washington
Core-collapse supernovae are the catastrophic deaths of massive stars. Ultraviolet observations are needed to understand the energy of the explosion through the study of the bolometric light curves .Early-time ultraviolet observations constrain the size of the progenitor. Ultraviolet spectra can break the degeneracies between temperature/ionization, reddening, and metallicity which hinder our understanding of ultraviolet photometry. Optical observations of high-redshift supernovae probe rest-frame ultraviolet wavelengths, requiring space-based observations of nearby supernovae against which to compare. Ultraviolet observations of core-collapse supernovae can also help distinguish them from type Ia supernovae, enabling cleaner photometric type Ia supernova samples for cosmological measurements. The Ultraviolet/Optical Telescope (UVOT) on the Swift satellite has observed over two hundred core-collapse supernovae in the ultraviolet, including sixty-nine ultraviolet grism spectra of twenty core-collapse SNe. Additional ultraviolet spectra have been obtained by the International Ultraviolet Explorer, Hubble Space Telescope, and Galaxy Evolution Explorer. We propose a project to reduce the Swift grism spectra and combine with the other ultraviolet and ground-based optical/NIR spectra to create timeseries bolometric spectra. We will use these bolometric spectra to better understand temperature, reddening, and metallicity and create bolometric light curves of these core collapse SNe. We will also use early time ultraviolet photometry and spectroscopy to constrain the progenitors of core collapse SNe. The ultraviolet observations fill a critical niche in our understanding of core collapse supernovae, and this program will enhance the scientific use of this important dataset from multiple space missions. Beyond core-collapse supernovae, the templates will allow studies of the dust properties around the progenitor systems (including the wavelength dependence of the extinction). The templates will improve the photometric classification and distance bias modeling for Type Ia supernova cosmology, while the extinction and temperature constraints will improve the use of type IIP supernovae as a distinct distance indicator on their own.
Supernova Key Project: Swift Response to New Transients
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/230; NASA-Goddard Space Flight Center
This proposal describes a multi-year, Swift Key Project to observe all nearby (d < 35 Mpc) transients (mostly expected to be SNe) with Swift within 24 hour of discovery (even before they are spectroscopically classified). The proposed investigation aims to obtain early UV and X-ray data on 60 transients in a distance-limited sample. This program will acquire a type-blind sample of all nearby SN, which would be useful to search for the early shocks in unbiased samples for both Type Ia (shocked companions) and CC SNe (shock breakouts). For Type Ia SNe, the proposed program would be effective in detecting UV emission from the shocked companion. For CCSN the proposed program would be effective in detecting shock breakout and cooling. These results would be useful for constraining the nature of the SN progenitors and their environments. This program is the first attempt to comprise a complete distance-limited SN sample in UV (for a given 2-yr period).
Swift and SIRAH: UV to NIR observations of Type Ia Supernovae Beyond the Twilight Zone
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/230; NASA-Shared Services Center
While Swift observations have uncovered a large diversity in the UV luminosities of Type Ia Supernovae (SNe Ia), the physical origin of the diversity of these standard candles and the cosmological impact is still unknown. We propose to observe a sample of twenty-four Type Ia Supernovae (SNe Ia) in the nearby Hubble flow with Swift’s Ultra-Violet/Optical Telescope (UVOT). In coordination with the Hubble Space Telescope’s (HST) SIRAH program, these SNe will have well-measured peak absolute magnitudes encompassing the UV, optical, and near-infrared (NIR). Analysis of these observations will show whether the physical cause of the UV dispersion already observed in the UV peak magnitudes and colors also has an impact on the optical luminosities, thereby affecting the usefulness of SNe Ia as standard candles. The sensitivity of the UV to many of the systematic uncertainties (metallicity, extinction, viewing angle, etc) may allow the identification and correction of differences between otherwise “standard” candles. This program capitalizes on Swift’s unique strengths of rapid response, short term scheduling, and UV capabilities to improve our understanding of the standard candles essential to studies of the expanding universe.