Griffin Hosseinzadeh (University of Arizona)Type Ibn Supernovae🎊 Happy MJD 60000! 🎊ObservationalProperties

Griffin Hosseinzadeh

Type Ibn = Interaction with Hydrogen-poor Circumstellar Material

SN 2006jc
Pastorello+2007

Griffin Hosseinzadeh

Almost all SN Ibn papers are on a single event. We need a sample!

Hosseinzadeh+2017

griffin Hosseinzadeh

Light Curves are Fast and Homogeneous

Hosseinzadeh+2017

Griffin Hosseinzadeh

Photometric Properties▸ Bright (Mr < -17 mag)
▸ Fast rise (mostly <10 days)▸ Fast decline (~0.1 mag/day)fi▸ No signi cant correlations
between these parameters

Hosseinzadeh+2017

Griffin Hosseinzadeh

SNe Ibn ⊂ Fast Transients▸ M < −16.5 mag, t½ < 12 days
▸ Some SNe Ibn show blue continuum
spectra within a week of peak
▸ Are these the same thing but withthe helium hidden?
▸ But unlike AT 2018cow, no x-ray,radio, or mm emission is detected(Ho+21)

data from Drout+14; see also Ho+21

Griffin Hosseinzadeh

SNe Ibn ⊂ Fast Transients

Fox & Smith 2019

Griffin Hosseinzadeh

Early Spectra Can Be Different▸ Blue continuum + P Cygni▸ Broad features + emission▸ All look similar after ~1 month,
implying a physical relationshipHosseinzadeh+2017

Griffin Hosseinzadeh

Lines Get Broader & Stronger With Time

Hosseinzadeh+2017

Griffin Hosseinzadeh

Many SNe Ibn Show Hydrogen Lines▸ Some are truly in between: equal strength H and He (SNCC2i0.5)▸ both in P Cygni (e.g., SN 2005la) and pure emission (e.g., SN 2011hw)▸ Some are helium dominated but with very weak H emission (SNCC2i0.9)▸ some of these do not show H until late times (e.g., SN 2006jc)▸ some show it early in ash spectra (Pastorello+15; Gangopadhyay+20,22)

fl▸ Keep in mind that host contamination and spectral resolution are problems

Griffin Hosseinzadeh

What is this telling us?
Smith+2015▸ Different CSM density pro les
P Cygni = optically thick CSM
emission = ejecta + optically thin CSM▸ Observational bias
Maybe all SNe Ibn would show P Cygni lines
if observed earlyfi▸ Viewing angle effectNonspherical CSM (from binary interaction)?

Griffin Hosseinzadeh

Host Galaxies of SNe Ibn▸ All detected in SDSS u’ images,or nondetection is not constraining▸ UV emission implies the presence of massivestars

Hosseinzadeh+2019

Griffin Hosseinzadeh

Direct Progenitor Detections▸ SNe 2006jc and 2019uo had
precursor eruptions (Pastorello+07;Strotjohann+21)▸ Binary companion detected for
SN 2006jc (Maund+16; Sun+20)▸ So far, no direct detection of aquiescent progenitor

Sun+2020

Now that I’ve convinced youthese are massive stars…

Griffin Hosseinzadeh

PS1-12sk = Type Ibn Supernova in a Brightest Cluster Galaxy

Sanders+2013

Griffin Hosseinzadeh

Identical in Every Way to Other Type Ibn Supernovae

Sanders+2013

Griffin Hosseinzadeh

HST Observations (Cycle 26)▸ Search for low-level of starformation undetected bySanders et al.
▸ Deepened the limit by anorder of magnitude!

Hosseinzadeh+2019

Griffin Hosseinzadeh

Rules Out All But One previous Core-Collapse Host at 5σ

Hosseinzadeh+2019

Griffin Hosseinzadeh

Remaining Possibilities▸ Progenitor was ejected or tidally stripped from the nearby ultra-compact dwarf▸ if we assume a progenitor lifetime of ~5 Myr, velocity must be >500 km/s
▸ lifetime could be extended by binary interaction▸ Luck: very low level of star formation, very statistically improbable observation▸ Some or all Type Ibn supernovae come from low-mass progenitors▸ but remember you also have to explain the precursor eruptions

Theoretical Work

mostly done by people that were here last week – I am the least qualified to explain any of thisGriffin Hosseinzadeh

Mass Loss Mechanisms▸ Wolf-Rayet winds (“default” since the rst SN Ibn papers; Maeda & Moriya 22)▸ Pulsational pair instability (Woosley 17; Renzo+20)

fi▸ Wave-driven mass loss (Fuller & Ro 20; Wu & Fuller 22a,b)

Griffin Hosseinzadeh

Binary Evolution▸ “Normal” binary stripping, leading to a helium star that can then explode(Laplace+20,21)▸ WR+BH or WR+NS merger (Metzger 22)fi▸ I wish there were more papers speci cally looking at the viability of these ultrastripped supernovae as SNe Ibn! [Tell me if I’m missing some.]

SummaryGriffin Hosseinzadeh

Summary & Future Work▸ Type Ibn supernovae are a rare class of explosions whose ejecta interact withhydrogen-poor circumstellar material. I think that’s all we know for sure.
▸ Their increasing sample size will help us understand their progenitors.
▸ likely to see more precursor eruptions in, e.g., LSST
▸ host galaxy statistics will help identify if they all come from massive stars▸ There are many new events with great data. It’s time for a new sample paper!