Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Astrophysics and Astronomy
Extraordinary Late‐Time Infrared Emission Of Type Iin Supernovae, Christopher L. Gerardy, Robert A. Fesen, Ken-Ichi Nomoto, Peter M. Garnavich
Extraordinary Late‐Time Infrared Emission Of Type Iin Supernovae, Christopher L. Gerardy, Robert A. Fesen, Ken-Ichi Nomoto, Peter M. Garnavich
Dartmouth Scholarship
Near-infrared observations are presented for five Type IIn supernovae (SN 1995N, SN 1997ab, SN 1998S, SN 1999Z, and SN 1999el) that exhibit strong infrared excesses at late times (t > 100 days). H- and K-band emission from these objects is dominated by a continuum that rises toward longer wavelengths. The data are interpreted as thermal emission from dust, probably situated in a preexisting circumstellar nebula. The IR luminosities implied by single-temperature blackbody fits are quite large, >1041-1042 ergs s-1, and the emission evolves slowly, lasting for years after maximum light. For SN 1995N, the integrated energy release via …
Sensitivity Of The Cosmic Microwave Background Anisotropy To Initial Conditions In Quintessence Cosmology, Rahul Dave, R. R. Caldwell, Paul J. Steinhardt
Sensitivity Of The Cosmic Microwave Background Anisotropy To Initial Conditions In Quintessence Cosmology, Rahul Dave, R. R. Caldwell, Paul J. Steinhardt
Dartmouth Scholarship
We analyze the evolution of energy density fluctuations in cosmological scenarios with a mixture of cold dark matter and quintessence, in which the quintessence field is modeled by a constant equation of state. We obtain analytic expressions for the time evolution of the quintessence perturbations in models with light fields. The fluctuations behave analogously to a driven harmonic oscillator, where the driving term arises from the inhomogeneities in the surrounding cosmological fluid. We demonstrate that the homogeneous solution, determined by the initial conditions, is completely subdominant to the inhomogeneous solution for physically realistic scenarios. Thus we show that the cosmic …
Optical And Ultraviolet Spectroscopy Of Sn 1995n: Evidence For Strong Circumstellar Interaction, Claes Fransson, Roger A. Chevalier, Alexei V. Filippenko, Bruno Leibundgut, Aaron J. Barth, Robert A. Fesen, Robert P. Kirshner, Douglas C. Leonard, Weidong Li, Peter Lundqvist, Jesper Sollerman, Schuyler D. Van Dyk
Optical And Ultraviolet Spectroscopy Of Sn 1995n: Evidence For Strong Circumstellar Interaction, Claes Fransson, Roger A. Chevalier, Alexei V. Filippenko, Bruno Leibundgut, Aaron J. Barth, Robert A. Fesen, Robert P. Kirshner, Douglas C. Leonard, Weidong Li, Peter Lundqvist, Jesper Sollerman, Schuyler D. Van Dyk
Dartmouth Scholarship
Optical and ultraviolet observations of the Type IIn supernova SN 1995N at epochs between 321 and 1799 days after the explosion show three distinct velocity components. The narrow lines come from circumstellar gas and show both low and high ionization. This component has a low filling factor and is photoionized by X-rays from the shock. The intermediate component, which is dominated by newly processed oxygen, originates in a shell with velocity of 2500-5000 km s-1 and most likely comes from the ejecta. The hydrogen- and helium-dominated gas has a low ionization, a high density, and velocities that extend out …
The Qmap And Mat/Toco Experiments For Measuring Anisotropy In The Cosmic Microwave Background, A. Miller, J. Beach, S. Bradley, R. Caldwell, H. Chapman, M. J. Devlin, W. B. Devlin, W. B. Dorwart, T. Herbig, D. Jones, G. Monnelly, C. B. Netterfield, M. Nolta, L. A. Page, J. Puchalla, T. Robertson, E. Torbet, H. T. Tran, W. E. Vinje
The Qmap And Mat/Toco Experiments For Measuring Anisotropy In The Cosmic Microwave Background, A. Miller, J. Beach, S. Bradley, R. Caldwell, H. Chapman, M. J. Devlin, W. B. Devlin, W. B. Dorwart, T. Herbig, D. Jones, G. Monnelly, C. B. Netterfield, M. Nolta, L. A. Page, J. Puchalla, T. Robertson, E. Torbet, H. T. Tran, W. E. Vinje
Dartmouth Scholarship
We describe two related experiments that measured the anisotropy in the cosmic microwave background (CMB). QMAP was a balloon-borne telescope that flew twice in 1996, collecting data on degree angular scales with an array of six high electron mobility transistor-based amplifiers (HEMTs). QMAP used an interlocking scan strategy to directly produce high signal-to-noise ratio CMB maps over a limited region of sky. The QMAP gondola was then refitted for ground-based work as the MAT/TOCO experiment. Observations were made from 5200 m on Cerro Toco in Northern Chile in 1997 and 1998 using time domain beam synthesis. MAT/TOCO measured the rise …