Detection of pre-SN outbursts
and SN progenitor stars
Nora Linn StrotjohannInteracting SN workshop
2023-02-10
nora.linn.strotjohann@gmail.com

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The Zwicky Transient FacilitySurvey

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The Zwicky Transient FacilitySurvey
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Large field of viewof 47 sqdeg or
0.1% of the sky
Survey has beenrunning since late2017 (g,r,i bands)(co-) discovers~2000 SNe/year(80% of all SNe)
Spectroscopic
follow up with theP60 telescope andothers

Pre-SN outbursts prior tointeracting SNe
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systematic search for outbursts prior to 196 SNe (131 of them SNe IIn) using
1e5 ZTF observations (Strotjohann et al. 2021)
earlier work: Ofek et al. (2014) 5000 PTF observations & Bilinski et al. (2015)
700 KAIT observations & many single object papers
archival observations for up to 2.5 years before SN (typically just ~1 year)Pre-SN outbursts prior tointeracting SNe●●5calculate forced photometry light curves (Yao et al. 2019)quality cuts: unflagged, low seeing, no bad pixels, low std in bg region, small
error on flux, image subtraction works for nearby star●

70000 out of 95000 pre-SN images remaining●base line correction, rescale flux error bars based on local scatterQuantifying the number offalse detections●

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test search at:1) empty positions
2) a star in the field (to remove badsubtractions)
3) position mirrored at host center

5364) positions of PTF SNe
5) actual SN position

Quantifying the number offalse detections●

test search at:1) empty positions

12) a star in the field (to remove badsubtractions)23) position mirrored at host center54) positions of PTF SNe5) actual SN position

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quality cuts remove 97% of false
detections 26% of data

unbinned data
empty positions (136 338 images)

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mirrored positions (33 600)

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3 detections (1 object)

4 (1)PTF SNe (36 300)

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7-day bins

Quantifying the number offalse detections●

test search at:1) empty positions

12) a star in the field (to remove badsubtractions)23) position mirrored at host center54) positions of PTF SNe5) actual SN position

3●

quality cuts remove 97% of false
detections 26% of data

unbinned data
empty positions (136 338 images)

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mirrored positions (33 600)

02

3 detections (1 object)

4 (1)PTF SNe (36 300)

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7-day bins
badrefimagebkg
AGN

Quantifying the number offalse detections●

test search at:1) empty positions

12) a star in the field (to remove badsubtractions)

23) position mirrored at host center54) positions of PTF SNe
5) actual SN position

3●

quality cuts remove 97% of false
detections 26% of data

unbinned data
empty positions (136 338 images)

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mirrored positions (33 600)

02

3 detections (1 object)

4 (1)152 detections (16 objects)

84 (18)PTF SNe (36 300)

97-day bins

actual SN positions (70 420)

Detected precursors
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search unbinned and binned light
curves for 5 sigma detections (1, 3,7, 15, 30 and 90-day bins)
precursor eruptions found prior to
18 SNe IIn and 1 SN Ibn
in addition 1 AGN, 4 “unconfirmed”
precursors =single data points

R-band precursor light curves●●●11often a few months long, typically detected immediately before SN
slow evolution likely requires continuous energy injection (interaction orwind?)high radiative energies of up to 1e49 erg

Precursor light curves

Galactic LBVs (mean Gaia g-band mag)

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Precursor colors●

large scatter and large errorbars●

typically red (=low temperatures) → light diffusing out from a photosphere

SN2009ip 28 days before the SN
Margutti et al. (2013)13

Precursor impact on the SNlight curve
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precursors detected formost nearby SNeSNe with detected
precursors not brighter thanother SNe IIn (aftercorrecting for impact of z)
brighter SNe have brighter
precursors
most detected outbursts
cannot explain narrow lines
observed in spec. at peak
SNe with detected precursors not significantly different→ we are likely detecting the last and brightest out of many eruptions

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Common properties of SNewith energetic precursors●●

100-day-long slowly risingoutburst immediately prior to SN
quick rise to peak (part of fast
population by Nyholm et al. 2020)●not very long-lasting●

undulations in fading SN●

broad spectral features at latertimes (SN2009ip, SN2019zrk)

Fransson et al. (2022) A&A 666, A79

Nyholm et al. (2020)15

Precursor rate●

select SNe IIn with deep enough observations in at least 2 out of 3 months●

calculate fraction with detected precursors (for 30-day bins)●

compared to earlier precursors: rate of faint precursors increases by x5, rateof bright precursors by x10

25% of TypeIIn SNe havefaintprecursors(<-13th mag)

164% havebrightprecursors

Precursor energies●●

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brightest precursors haveobserved energy of 1049 erg(1-10% of a typical SN)
brightest progenitors:
accelerate 1 Msun to 1000
km/s and crash it into evenmore massive CSM toconvert complete kinetic
energy to radiation

Precursor energies
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brightest precursors haveobserved energy of 1049 erg(1-10% of a typical SN)
brightest progenitors:
accelerate 1 Msun to 1000
km/s and crash it into evenmore massive CSM toconvert complete kinetic
energy to radiationlate nuclear burning stages (order of magnitude estimates for 25 Msun star):●

Carbon: 1e50 erg produced in 1000 years●

Neon: 1e50 erg in 1 yr●

Oxygen: 1e51 erg in 1 yr●

Silicon: 3e50 erg in 1 day}time scale matches precursors

Wave-driven mass loss●

Shiode & Quataert (2012):●●●

outbursts not energetic enoughfor lower mass staroutburst too short for high-masscore

Wu & Fuller (2020):●●●

15 Msun core:
5e46 erg
100d before SN

40 Msun core:
1e48 erg
1d before SN

100 days 1day

most power for angularwavenumber l>1
these waves are dampened
more strongly
no outbursts expected stars withmassive H envelope●Alternatives?

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Which measurements could help?

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brightest detected precursors:
1e49 erg, started 100d before SN

Shiode & Quataert 2012

Precursor prior to the Ibn
SN2019uo
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closest SN Ibn in sample
precursor lumi. and duration
similar to SN2006jc (2yrs before
SN; Pastorello et al. 2007)
spectral lines indicate CSM
velocity of ~700km/s-> reaches radius of 2e15 cm
Gangopadhyay et al. (2020):●

broad features become visible 18 days after explosion●

light curve modelling requires 0.4-0.7 Msun of CSM at 0.2-2e15 cm

precursor energy is 1.7e47 erg
precursor can explain LC and spectra if 1-2% of kin. energy converted toradiation
mass ejection comparable to SNe IIn, but lower radiative efficiency

Precursors prior to different
SN types●

individual precursors also detected prior to different SN types/progenitor stars●

working on systematic search

SN IInLBV

SN Ibn;WR star?

21SN IIP; RSG
Strotjohann et.
al (in prep.)

flash SN II;
RSGJacobsonGalan et. al(2021)

SN Ic-BL;carbon star
Ho et. al(2019)

Summary●●many (>25%) Type IIn progenitors undergo bright eruptions in the lastmonths before their explosion
they have earlier, less bright/frequent, outbursts & they are alreadysurrounded by CSM at this time●outbursts coincide with the oxygen (maybe neon) burning phase●most extreme eruptions release 1e49 erg

Open questions:●

What triggers the outbursts?

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How massive are the progenitor stars?

●How common are they for other SN/progenitor types?

22Progenitor search withground-based surveys●

thousands of ground-based images as good as an HST image?

●need image subtraction due to blurring by atmosphere
SNIIn in ZTF data
Sollerman et al. (2021); SN2020jfo
HST F814W

SN2011dh PTF data

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size of a ZTF pixelProgenitor search for ZTF SNe
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prove of principle: select the closest 29 CCSNe from the Bright Transient
Survey (Perley et al. 2020) that have already faded
forced-photometry light curves: compare pre-SN to late-time fluxes

Results of ZTF progenitorsearch●●●test: run analysis for 20 positions in same images -> scale up errors if
residuals larger than expected
potential reasons: bright hosts, long-term changes, shallow reference
imagesone detection: 6-months-long blue outburst 2 years prior to an SN IIP (veryblue color unexpected for RSG)

single science image

limiting magnitude

21.0

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21.5
22.0
22.5
23.0
23.5
24.0

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100

150

200

# images minimum(early, late)250

Comparison with progenitor
detections from literature●●●26ZTF is too small to detect progenitors except bright YSG or progenitors
within a few Mpc
the r band is too blue (RSG with M4 spectrum are 1.5mag brighter in the iband)prospects for LSST

LSST sensitivity to SNprogenitors●

simulate nearby SN population using galaxy catalog●

progenitor magnitudes from RSG progenitor luminosity function●

SN fading time from ZTF sample (r band)●

LSST sensitivity from Ivezić et al. (2019)●

correct LSST sensitivity for host impact (44% of SNe host dominated)-> 1/3 of progenitors remain undetected due to bright host27

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median LSST limit 26.0 mag in
the r band and 25.6 mag (g & i)progenitor detection prob.

Progenitor detections withLSST
0.8
0.6
0.40.20.0

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RSG with M4 spectrum

1.0010203040

distance [Mpc]506070●

median LSST limit 26.0 mag in
the r band and 25.6 mag (g & i)
expected progenitor detections:●30-50 RSG (i band)●

3-5 BSG and YSG●

SN Ib progenitors if <-4.9mag●

SN Ic progenitors if <-4.2mag●

29130 searches sensitive
to RSGs with -8.25 mag(= 5.23 Lsun = 17 – 20 Msun)1.010RSG with M4 spectrum

expected number of SNe II●

progenitor detection prob.

Progenitor detections withLSST
0.880.6

60.4

40.2

20.00102030

distance [Mpc]40500The Weizmann AstronomicalObservatory●●

using small off-the-shelf telescopes instead of big ones is cheaper
possible now due to powerful computers and commercial availability ofcameras with small pixels●

LAST: unfiltered survey●

FAST: 25Hz astroid search●

PAST: photometric follow up●

MAST: spec. follow up●

Ultrasat: UV satellite●www.weizmann.ac.il/wao

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