Astrophysics in 1996

Trimble, Virginia; McFadden, L. A.

doi:10.1086/133865

Cited by 3 publications

(1 citation statement)

References 467 publications

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“…A satisfactory progenitor scenario for SNI has not yet emerged (e.g., Nomoto et al 1997;Trimble & McFadden 1998). Leading models invoke single-degenerate (SD) (Whelan & Iben 1973;Iben & Tutukov 1984) or double-degenerate (DD) systems (Webbink 1984;Iben & Tutukov 1984),i.e., distinguished by the nature of the white dwarf companion.…”

Section: Progenitors Of Type Ia Supernovaementioning

confidence: 99%

The Diffuse Gamma‐Ray Background from Supernovae

Watanabe

Hartmann

Leising

1999

ApJ

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The diffuse extragalactic γ-ray background in the MeV region is believed to be due to photons from radioactivity produced in supernovae throughout the history of galaxies in the universe. In particular, γ-ray line emission from the decay chain 56 Ni → 56 Co → 56 Fe provides the dominant photon source (Clayton & Silk 1969). Although iron synthesis occurs in all types of supernovae, the contribution to the background is dominated by Type Ia events due to their higher photon escape probabilities. Estimates of the star formation history in the universe suggest a rapid increase by a factor ∼ 10 from the present to a redshift z p ∼ 1.5, beyond which it either remains constant or decreases slowly. Little is known about the cosmological star formation history for redshift exceeding z ∼ 5. We integrate the observed star formation history to determine the Cosmic Gamma-Ray Background (CGB) from the corresponding supernova rate history. In addition to γ-rays from short-lived radioactivity in SNIa and SNII/Ib/Ic we also calculate the minor contributions from long-lived radioactivities ( 26 Al, 44 Ti, 60 Co, and electron-positron pair annihilation). The time-integrated γ-ray spectrum of model W10HMM (Pinto & Woosley 1988a, Pinto & Woosley 1988b was used as a template for Type II supernovae, and for SNIa we employ model W7 (Nomoto et al. 1984). Although progenitor evolution for Type Ia supernovae is not yet fully understood, various arguments suggest delays of order 1−2 Gy between star formation and the production of SNIa's. The effect of this delay on the CGB is discussed. We emphasize the value of γ-ray observations of the CGB in the MeV range as an independent tool for studies of the cosmic star formation history. If the delay between star formation and SNIa activity exceeds 1 Gy substantially, and/or the peak of the cosmic star formation rate occurs at a redshift much larger than unity, the γ-ray production of SNIa would be insufficient to explain the observed CGB and a so far undiscovered source population would be implied. Alternatively, the cosmic star formation rate would have to be higher (by a factor 2-3) than commonly assumed, which is in accord with several upward revisions reported in the recent literature.

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Section: Progenitors Of Type Ia Supernovaementioning

confidence: 99%

The Diffuse Gamma‐Ray Background from Supernovae

Watanabe

Hartmann

Leising

1999

ApJ

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The Impact of Space Experiments on Our Knowledge of the Physics of the Universe

Giovannelli

Sabau-Graziati

2004

The Impact of Space Experiments on Our Knowledge of the Physics of the Universe

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One of Everything: The Breakthrough Listen Exotica Catalog

Lacki

Brzycki

Croft

et al. 2021

ApJS

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We present Breakthrough Listen’s Exotica Catalog as the centerpiece of our efforts to expand the diversity of targets surveyed in the Search for Extraterrestrial Intelligence (SETI). As motivation, we introduce the concept of survey breadth, the diversity of objects observed during a program. Several reasons for pursuing a broad program are given, including increasing the chance of a positive result in SETI, commensal astrophysics, and characterizing systematics. The Exotica Catalog is a 963 entry collection of 816 distinct targets intended to include “one of everything” in astronomy. It contains four samples: the Prototype sample, with an archetype of every known major type of nontransient celestial object; the Superlative sample of objects, with the most extreme properties; the Anomaly sample of enigmatic targets that are in some way unexplained; and the Control sample, with sources not expected to produce positive results. As far as we are aware, this is the first object list in recent times with the purpose of spanning the breadth of astrophysics. We share it with the community in hopes that it can guide treasury surveys and as a general reference work. Accompanying the catalog is an extensive discussion of the classification of objects and a new classification system for anomalies. Extensive notes on the objects in the catalog are available online. We discuss how we intend to proceed with observations in the catalog, contrast it with our extant Exotica efforts, and suggest how similar tactics may be applied to other programs.

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Astrophysics in 1996

Cited by 3 publications

References 467 publications

The Diffuse Gamma‐Ray Background from Supernovae

The Diffuse Gamma‐Ray Background from Supernovae

The Impact of Space Experiments on Our Knowledge of the Physics of the Universe

One of Everything: The Breakthrough Listen Exotica Catalog

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