4 research outputs found
A Large Fraction of Hydrogen-rich Supernova Progenitors Experience Elevated Mass Loss Shortly Prior to Explosion
Spectroscopic detection of narrow emission lines traces the presence of circumstellar mass distributions around massive stars exploding as core-collapse supernovae. Transient emission lines disappearing shortly after the supernova explosion suggest that the material spatial extent is compact and implies an increased mass loss shortly prior to explosion. Here, we present a systematic survey for such transient emission lines (Flash Spectroscopy) among Type II supernovae detected in the first year of the Zwicky Transient Facility survey. We find that at least six out of ten events for which a spectrum was obtained within two days of the estimated explosion time show evidence for such transient flash lines. Our measured flash event fraction (>30% at 95% confidence level) indicates that elevated mass loss is a common process occurring in massive stars that are about to explode as supernovae
The prevalence and influence of circumstellar material around hydrogen-rich supernova progenitors
Narrow transient emission lines (flash-ionization features) in early
supernova (SN) spectra trace the presence of circumstellar material (CSM)
around the massive progenitor stars of core-collapse SNe. The lines disappear
within days after the SN explosion, suggesting that this material is spatially
confined, and originates from enhanced mass loss shortly (months to a few
years) prior to explosion. We performed a systematic survey of H-rich (Type II)
SNe discovered within less than two days from explosion during the first phase
of the Zwicky Transient Facility (ZTF) survey (2018-2020), finding thirty
events for which a first spectrum was obtained within days from
explosion. The measured fraction of events showing flash ionisation features
( at confidence level) confirms that elevated mass loss in
massive stars prior to SN explosion is common. We find that SNe II showing
flash ionisation features are not significantly brighter, nor bluer, nor more
slowly rising than those without. This implies that CSM interaction does not
contribute significantly to their early continuum emission, and that the CSM is
likely optically thin. We measured the persistence duration of flash ionisation
emission and find that most SNe show flash features for days.
Rarer events, with persistence timescales days, are brighter and rise
longer, suggesting these may be intermediate between regular SNe II and
strongly-interacting SNe IIn
The prevalence and influence of circumstellar material around hydrogen-rich supernova progenitors
Narrow transient emission lines (flash-ionization features) in early supernova (SN) spectra trace the presence of circumstellar material (CSM) around the massive progenitor stars of core-collapse SNe. The lines disappear within days after the SN explosion, suggesting that this material is spatially confined, and originates from enhanced mass loss shortly (months to a few years) prior to explosion. We performed a systematic survey of H-rich (Type II) SNe discovered within less than two days from explosion during the first phase of the Zwicky Transient Facility (ZTF) survey (2018-2020), finding thirty events for which a first spectrum was obtained within at confidence level) confirms that elevated mass loss in massive stars prior to SN explosion is common. We find that SNe II showing flash ionisation features are not significantly brighter, nor bluer, nor more slowly rising than those without. This implies that CSM interaction does not contribute significantly to their early continuum emission, and that the CSM is likely optically thin. We measured the persistence duration of flash ionisation emission and find that most SNe show flash features for days. Rarer events, with persistence timescales days, are brighter and rise longer, suggesting these may be intermediate between regular SNe II and strongly-interacting SNe IIn
A large fraction of hydrogen-rich supernova progenitors experience elevated mass loss shortly prior to explosion
Spectroscopic detection of narrow emission lines traces the presence of circumstellar mass distributions around massive stars exploding as core-collapse supernovae. Transient emission lines disappearing shortly after the supernova explosion suggest that the spatial extent of such material is compact, and hence imply an increased mass loss shortly prior to explosion. Here, we present a systematic survey for such transient emission lines (Flash Spectroscopy) among Type II supernovae detected in the first year of the Zwicky Transient Facility (ZTF) survey. We find that at least six out of ten events for which a spectrum was obtained within two days of estimated explosion time show evidence for such transient flash lines. Our measured flash event fraction ( at confidence level) indicates that elevated mass loss is a common process occurring in massive stars that are about to explode as supernovae