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Fast Optical Transients
Maria R. Drout
Harvard-Smithsonian Conference on Theoretical Astrophysics
May 18th, 2016
Collaborators
Edo Berger
Ryan Chornock
Bob Kirshner
Ryan Foley
Alicia Soderberg Dan Milisavljevic Raffaella Margutti
Armin Rest
Atish Kamble
Jerod Parrent
+ the PS1
Team
Ragnhild Lunnan
Tanmoy Laskar
Nathan Sanders Wen-fai Fong
M. R. Drout et al.
SN Phase Space
SN Phase Space
SN Phase Space
PS1 Type IIn SN
SN Phase Space
SN Phase Space
Optical Emission from SN
Radioactive Decay
(20-50 days)
Hydrogen Recombination
(Type IIP, IIL)
Circumstellar Interaction
Luminosity -->
(Type Ia, Type Ibc)
(100s days)
(Type IIn)
(50 – 100s days)
Time -->
Time Scale Implications
Radioactive Decay
Photon diffusion
Small Mej/High Ek
Hydrogen Recombination
(Type IIP, IIL)
Circumstellar Interaction
(Type IIn)
Luminosity -->
(Type Ia, Type Ibc)
Small MH
Sharp change in ρCSM
Small range of dense CSM
Time -->
Rapidly Evolving Transients
•  Probe the extremes of both the configuration of the progenitor
star and the explosion parameters themselves.
Rapidly Evolving Transients
•  Probe the extremes of both the configuration of the progenitor
star and the explosion parameters themselves.
•  Detailed modeling is necessary to determine if they are extreme
examples of progenitors we know, or entirely new types of
transients.
•  e.g. SN2005ek (Drout et al. 2013; Tauris et al. 2013),
SN2010X (Kasliwal et al. 2010; Kleiser & Kasen 2014).
Rapidly Evolving Transients
•  Probe the extremes of both the configuration of the progenitor
star and the explosion parameters themselves.
•  Detailed modeling is necessary to determine if they are extreme
examples of progenitors we know, or entirely new types of
transients.
•  e.g. SN2005ek (Drout et al. 2013; Tauris et al. 2013),
SN2010X (Kasliwal et al. 2010; Kleiser & Kasen 2014).
Rapidly Evolving Transients
PS1the
Typeconfiguration
IIn SN
•  Probe the extremes of both
of the progenitor
star and the explosion parameters themselves.
Fig. 4.—
Rapidly-Declining Type I SN
SN2005ek
Peculiar Type Ic SN 2005ek
5
Drout, M. R. et al. (2013)
Fig. 4.— Left: Light curve of SN 2005ek (colored circles), normalized to peak magnitude/epoch and compared to other rapidly evolving
supernovae of Type I. The other events are SN 1994I, SN 2008ha, SN 1998de, SN 2005E (black circles), SN 2002bj (colored squares), and
SN 2010X (colored stars; R-band panel only). Right: R-band absolute magnitude light curves of SN 2005ek (purple circles), SN 2002bj
(blue squares), and SN 2010X (magenta stars). When error bars are not visible they are smaller than the plotted points.
Rapidly-Declining Type I SN
SN2005ek
The Astrophysical Journal, 774:58 (18pp), 2013 September 1
Drout et
Drout, M. R. et al. (2013)
Figure 16. Comparison of the pseudo-bolometric light curve of SN 2005ek (red stars) to theoretical light curves. Far left: two AIC models from Darbha et al. (201
Both models are calculated for Mej = 10−2 M" . Middle left: the NS–NS merger from Metzger et al. (2010), the WD–BH merger from Metzger (2012), and
WD–NS merger from Metzger (2012). Middle right: two “.Ia” models from (Shen et al. 2010). Models 1 and 2 represent the detonation of a 0.1 M" He shell o
1.0 M" WD and a 0.05 M" He shell on a 1.2 M" WD, respectively. Far right: two edge-lit double-detonation models from Sim et al. (2012). Models 1 and 2 repres
a 0.21 M" He shell on a 0.58 M" and 0.45 M" WD, respectively.
(A color version of this figure is available in the online journal.)
“.Ia” Supernova: Detonation of a helium shell on a WD.
Predicted an ejecta dominated by Ca, Ti, and un-burnt He with a paucity of IMEs
Rapidly-Declining Type I SN
Figure 6. Selected spectrum calculated from our fiducial ejecta model of Fig. 4 shown against observed data. The overall shape is simil
the important spectral features are reproduced. Discrepancies may arise from our assumption of LTE, simplified power-law density structure
abundances assumed.
SN2005ek,
SN2010X
Drout et al.
Figure 10. SYN++ model fits to the −1 day, maximum-light, and +9 day
spectra of SN 2005ek (red lines). Observed spectra are shown inFigure
black.
Major
7. Time series of selected synthetic spectra of our fiducial ejecta model of Fig. 4 compared the observed data of SN 2010X showing
spectroscopic features are labeled.
the oxygen line and other prominent features. The order of the observed and synthetic spectra is chosen to highlight spectral similarities, som
more easily seen by comparison of spectra at slightly different phases.
(A color version of this figure is available in the online journal.)
Drout, M. R. et al. (2013)
Kleiser & Kasen (2014)
Spectroscopic modeling finds
an ejecta dominated by oxygen.
ejected very little radioactive material and the light curve was inlight curve can be understood as reflecting the end
stead powered by the diffusion of thermal energy deposited by the
plateau’. Our 1D radiation transport models demon
Likely not a “.Ia” SN. Possibly
an
extreme
core-collapse
SN.
explosion shock wave. The short duration of the light curve, deobservations of SN 2010X are consistent with this
spite the relatively high ejected mass (M ∼ 3–4 M" ), is due to
pirically, the spectral similarity of SN 2010X with th
(Drout et al. 2013, Tauris recombination,
et al. 2013,
Kleiser
&effective
Kasen
which dramatically
reduces the
opacity. 2014)
strongly suggests that these events have oxygen-dom
The evolution is similar to SNe IIP, and the sharp decline of the
as would be expected in stripped core-collapse SNe. S
56Ni
powered explosion
SN2005ek
The Astrophysical Journal, 774:58 (18pp), 2013 September 1
Cappella
where th
from nic
from the
and the
respectiv
S
S
S
SeC+
where
Drout, M. R. et al. (2013)
Figure 14. Radioactive models for the pseudo-bolometric light curve of
SN 2005ek. Black lines show the decay rates for 56 Ni, 56 Co, 48 Cr, and 48 V,
assuming full trapping of gamma-rays. The gold curve shows the best-fit model
The i
Introduction
 Galactic binary transients
Many stages where
transients occur….
Common envelope
contact binary mergers
This talk
X-ray transients
SN explosions
Intermittent pulsars,
RRATS, magnetars,
FRBs?
Ultra-stripped SNe
Geodetic precession
SFXTs
Be/X-ray
ULXs
LIGO sources
Image courtesy of T. Tauris
Introduction
 Galactic binary transients
Many stages where
transients occur….
Common envelope
contact binary mergers
This talk
X-ray transients
SN explosions
Intermittent pulsars,
RRATS, magnetars,
FRBs?
Ultra-stripped SNe
Geodetic precession
SFXTs
Be/X-ray
ULXs
LIGO sources
Image courtesy of T. Tauris
Ultra-Stripped SN
Tauris+2013
Secondary explosion leading to a compact binary can be ultra-stripped.
(Tauris+2013, Tauris+2015, Suwa+2015)
Oxygen-plateau SN
Figure 4. Light curves in g, r and i calculated for a pure explosion model of SN 2010X, plotted against the data. This model was obtained with Mej = 3.5 M! ,
E51 = 1 B and R0 = 2 × 1012 cm. The dashed lines show light curves in UBVRI for SN 1994I, a typical SN Ic, for comparison.
Kleiser & Kasen (2014)
Figure 5. Calculated light curves using parameter variations around our fiducial ejecta model for SN 2010X, which has parameters Mej = 3.5 M! , E51 = 1 B
and R0 = 2 × 1012 cm. Top left: light curve calculations holding all parameters constant except ejecta mass. Top right: same as the top-left panel but with
varying explosion energy. Bottom left: same as top-right and top-left panels but with varying pre-SN radius. Bottom right: an alternative model that fits the
data fairly well with parameters Mej = 6 M! , E51 = 3 B and R0 = 9 × 1011 cm. This demonstrates the degeneracy in our approach and that the light curves
SN2013ge
6
Type Ic SN withM. an
early
R. Drout
et al.emission component
The Astrophysical Journal, 821:57 (24pp), 2016 April 10
Drout et al.
Fig. 7.— U−B (left) and B−V color evolution of SN 2013ge in
comparison to other Type Ib/c SN. Shaded grey regions indicate
the timeframe of the first light curve component. During the falling
portion of the first light curve component (−8 to −5 days) the U−B
color reddens drastically. The B−V evolution of SN 2013ge is very
similar to other Type Ib/c SN.
probe the early rising portion of the first component.
Although well sampled u-band light curves between
−14 and −7 days relative to maximum light are still quite
Figure 18. Left: color temperature vs. time since explosion for cooling envelope emission from hydrogen-poor progenitors with radii between 1 and 50 R . Bands for
rare for Type I SN, no previous object has shown two diseach radius assume explosion parameters of Mej=2–3 M and EK = (1–2) ×1051 erg. If the early emission from SN 2013ge is due to cooling envelope emission,
tinct
components
withanthese
timescales.
Thisdecomposition
is demon- of the
then the temperature must remain above 10,000 K (0.9 eV) at a minimum for 4−6 days
post-explosion,
implying
extended
progenitor. Right:
56 panel of Figure 6 where we compile
strated
in
the
lower
bolometric luminosity of SN 2013ge (blue) into two components. The solid black line represents our best-fit Ni decay model to the bulk explosion. Red points show
u-band
the literature.
majority
the excess emission above this model at early times. The black dashed line is an Arnett
model light
fit to thecurves
rise timefrom
and luminosity
of this early A
component,
and of
the gold
56
56
56
Ni ∼4
Co
Fe
decay
chain,
allowing
for
incomplete
gamma-ray
line is a model for the decline phase based on the instantaneous energy deposition events
from the peak
days prior to V-band maximum and then
trapping. Dotted lines indicate the epochs of our early spectra.
decline rapidly, consistent with our inferred time of maximum and subsequent evolution for the second component
Fig. 6.— Top: Example decomposition of the u-band light curve
SN 2013ge.
1 day as
already
below this
bybe taken
post-explosion.
Using in epoch.
For deep deposits, there will be a “dark period” between
into two fallen
components.
Thislevel
should
representative only
Prior to this maximum, the evolution of the literature
Drout+2016
SN2013ge
Type Ic 5SN with an early emission component
al, 821:57 (24pp), 2016 April 10
Drout et al.
r whetherthis progenitor scenario can
spectra observed during the rise of the
onent. In particular, while this scenario
e temperature, the ions present in these
ngly ionized species. It is possible that
ual velocity profile of the lines, could be
a change in ionization state in the outer
associated with either the low-mass
a density enhancement due to a pren. In the former case, the presence of
mount of hydrogen could increase the
gh to lead to enhanced recombination
Tanaka et al. 2008).
2. Asymmetric Ejection
interpret the early emission as heating
nitude/epoch
and compared
other rapidly
evolving
ymmetric ejection
of atosmall
amount
of
05E (black circles), SN 2002bj (colored squares), and
ight curves
of SN 2005ek
circles),
SN 2002bj
high
velocities
could(purple
explain
both
the
are smaller than the plotted points.
k and the unusual velocity profile in
Intriguingly, our observed velocity
Figure 19. Comparison of an early spectrum of SN 2013ge to a spectrum of the
rapidly evolving SN 2002bj (Poznanski et al. 2010). The spectrum of
SN 2002bj has been linearly blueshifted by 8000 km s−1.
6.4. Comparison of the Early Emission Drout+2016
to the Rapidly
Declining SN 2002bj
While investigating the early spectra of SN 2013ge, we
Rapidly Evolving Transients
•  Probe the extremes of both the configuration of the progenitor
star and the explosion parameters themselves.
•  Detailed modeling is necessary to determine if they are extreme
examples of progenitors we know, or entirely new types of
transients.
•  e.g. SN2005ek (Drout et al. 2013; Tauris et al. 2013),
SN2010X (Kasliwal et al. 2010; Kleiser & Kasen 2014).
Rapidly Evolving Transients
•  Probe the extremes of both the configuration of the progenitor
star and the explosion parameters themselves.
•  Detailed modeling is necessary to determine if they are extreme
examples of progenitors we know, or entirely new types of
transients.
•  e.g. SN2005ek (Drout et al. 2013; Tauris et al. 2013),
SN2010X (Kasliwal et al. 2010; Kleiser & Kasen 2014).
•  The true nature and intrinsic rate of these events could influence
our understanding of various stages of stellar evolution.
SN Phase Space
Rapid Transients from PS1
•  Systematic search within
approximately 4000
transients discovered by
the PS1-MDS
•  10 Medium Deep Fields
(7.2 square degrees)
•  Daily cadence
(3-4 days for griz set)
PS1 Rapidly-Evolving Transients
Rapid Transients from PS1
PS1 Rapidly-Evolving Transients
3
3
Fig. 1.— PS1 absolute magnitude, rest-frame, light curves for gold sample transients. Circles represent grizP1 detections and triangles
represent 3σ upper limits. Vertical dashed lines indicate epochs when spectroscopic observations were acquired. The grey shaded region is
the R−band type Ibc template from Drout et al. (2011), normalized to the peak magnitude of the PS1-MDS transient.
Fig. 1.— PS1 absolute magnitude, rest-frame, light curves for gold sample transients. Circles represent grizP1 detections and triangles
represent 3σ upper limits. Vertical dashed lines indicate epochs when spectroscopic observations were acquired. The grey shaded region is
the R−band type Ibc template from Drout et al. (2011), normalized to the peak magnitude of the PS1-MDS transient.
Fig. 2.— Same as Figure 1 for silver sample objects.
Drout, M. R. et al. (2014)
SN Phase Space
SN Phase Space
Rapid Transients from PS1
PS1 Rapidly-Evolving Transients
MgII
[OII]
Hα
Hβ
Sample Properties:
Luminous
• 
Blue Colors
• 
• 
Spectra Dominated by
Continua
Star forming host galaxies
SN2002bj (+7d)
SN1993J (-18d)
PTF 09uj (+2d)
Normalized Flux (fλ) + Constant
• 
9
PS1-11bbq (+2d)
PS1-12bv (+2d)
PS1-13duy (+2d)
PS1-12brf (+4d)
PS1-12bb (+5d)
PS1-12bb (+33d)
SN2011fe (-15d)
SN2007gr (-4d)
SN2005ek (-1d)
Fig. 12.— Left Panel: Pseudo-bolometric light curves for the
gold and silver transients. Right Panel: Pseudo-bolometric light
curves for other rapidly-evolving transients from the literature: the
type Ic SN 2005ek (Drout et al. 2013) and 2010X (Kasliwal et al.
2010), the type Ib SN 2002bj (Poznanski et al. 2010), the type IIb
SN 1993J (Schmidt et al. 1993), and the type IIn PTF09uj (Ofek
et al. 2010).
SN2010X (+23 d)
4000
6000
8000
10000
Rest Wavelength (!)
by our highest redshift event, and the approximate range
of our spectra in Section 5.
Using this formulation, our peak pseudo-bolometric luminosities span a range of approximately 2×1042 ergs s−1
Drout, M. R. et al. (2014)
Fig. 13.— Explosion spectra for five PS1-MDS transients (colored) in comparison to events from the literature (black). With the
exception of PS1-12bb our events are dominated by a blue continuum, with a lack of strong P Cygni features. Some contributions
from the host galaxy (e.g. nebular emission lines) are still present
Rapid Transients from PS1
Implications for Progenitors
The properties of many of PS1 objects are more consistent with being powered by
interaction and/or shock break-out
and recombination than by radioactive
decay
FBOTs
15
Fig. 19.— A comparison of the light curves of several of our
objects to two events from the literature thought to be powered by
varieties of shock break-out/cooling envelope emission. PS1-10ah
shows a similar initial decline rate to the Type IIb SN 1993J, but
has a consecutive lack of a later peak powered by radioactive decay.
PS1-11qr, PS1-12bv, and a number of our other more luminous
events are very similar to PTF09uj, which was hypothesized to be
due to the shock break out from an optically thick wind (Ofek et al.
2010)
a massive star. While the shock break out from a massive star lasts only a matter of seconds (WR stars) to
hours (RSG) the process shock heats the ejecta which
then cools and recombines, giving rise to optical emission
which is independent from later emission powered by the
decay of radioactive elements. For instance, the Type IIb
SN 1993J showed an initial peak which declined ∼1 mag
in ∼5 days which is attributed to such cooling envelope
emission. In Figure 19 we compare the light-curve of
SN 1993J to several of our gold sample objects. We see
that the initial decline of SN 1993J is well matched to
the initial decline of our object PS1-10ah. However, the
rest of our objects seem to decline at a slower rate. One
possible explanation in that a larger fraction of the outer
envelope of these stars remain, leading to a longer recombination timescale (in their model of SN 1993J Woosley
et al. 1994 only invoke a 0.2 M! hydrogen envelope). We
also note that although many transients with bright cooling envelope emission are Type IIb SN, with a portion
of their hydrogen envelopes remaining, Kleiser & Kasen
(2014) has also modeled the Type Ic SN 2010X with the
main power source being oxygen, not hydrogen, recombination.
One important note regarding this as a possible power
source for our objects is the obvious lack of a second peak
due to the radioactive decay. In SN 1993J, a second peak,
of nearly the same peak magnitude in the visual bands,
was present ∼20 days after the explosion (Lewis & Walton 1994; Wheeler et al. 1993). This second peak is consistent with one powered by ∼0.07 M! of 56 Ni (Woosley
et al. 1994). As discussed above, no such obvious second
peak is evident in our transients. For instance, although
PS1-10ah shows a similar initial decline to SN 1993J we
can restrict the amount of Nickel powering a later peak
Drout, M. R. et al. (2014)
Rapid Transients from PS1
Implications for Progenitors
The properties of many of PS1 objects are more consistent with being powered by
interaction and/or shock break-out
and recombination than by radioactive
decay
FBOTs
15
a massive star. While the shock break out from a massive star lasts only a matter of seconds (WR stars) to
hours (RSG) the process shock heats the ejecta which
then cools and recombines, giving rise to optical emission
which is independent from later emission powered by the
decay of radioactive elements. For instance, the Type IIb
SN 1993J showed an initial peak which declined ∼1 mag
in ∼5 days which is attributed to such cooling envelope
emission. In Figure 19 we compare the light-curve of
SN 1993J to several of our gold sample objects. We see
that the initial decline of SN 1993J is well matched to
the initial decline of our object PS1-10ah. However, the
rest of our objects seem to decline at a slower rate. One
possible explanation in that a larger fraction of the outer
envelope of these stars remain, leading to a longer recombination timescale (in their model of SN 1993J Woosley
et al. 1994 only invoke a 0.2 M! hydrogen envelope). We
also note that although many transients with bright cooling envelope emission are Type IIb SN, with a portion
of their hydrogen envelopes remaining, Kleiser & Kasen
(2014) has also modeled the Type Ic SN 2010X with the
main power source being oxygen, not hydrogen, recombination.
One important note regarding this as a possible power
source for our objects is the obvious lack of a second peak
due to the radioactive decay. In SN 1993J, a second peak,
of nearly the same peak magnitude in the visual bands,
was present ∼20 days after the explosion (Lewis & Walton 1994; Wheeler et al. 1993). This second peak is consistent with one powered by ∼0.07 M! of 56 Ni (Woosley
et al. 1994). As discussed above, no such obvious second
peak is evident in our transients. For instance, although
PS1-10ah shows a similar initial decline to SN 1993J we
can restrict the amount of Nickel powering a later peak
Shock break out from an extended stellar envelope
Shock break out from an dense CSM
c.f. Type IIn PTF09uj; Ofek+2010
Type Ibn SN1999cq Matheson+2000
Type Ibn SN2015U Shivvers+2016
Fig. 19.— A comparison of the light curves of several of our
objects to two events from the literature thought to be powered by
varieties of shock break-out/cooling envelope emission. PS1-10ah
shows a similar initial decline rate to the Type IIb SN 1993J, but
has a consecutive lack of a later peak powered by radioactive decay.
PS1-11qr, PS1-12bv, and a number of our other more luminous
events are very similar to PTF09uj, which was hypothesized to be
due to the shock break out from an optically thick wind (Ofek et al.
2010)
Drout, M. R. et al. (2014)
Rapid Transients from PS1
Implications for Progenitors
The properties of many of PS1 objects are more consistent with being powered by
interaction and/or shock break-out
and recombination than by radioactive
decay
FBOTs
15
a massive star. While the shock break out from a massive star lasts only a matter of seconds (WR stars) to
hours (RSG) the process shock heats the ejecta which
then cools and recombines, giving rise to optical emission
which is independent from later emission powered by the
decay of radioactive elements. For instance, the Type IIb
SN 1993J showed an initial peak which declined ∼1 mag
in ∼5 days which is attributed to such cooling envelope
emission. In Figure 19 we compare the light-curve of
SN 1993J to several of our gold sample objects. We see
that the initial decline of SN 1993J is well matched to
the initial decline of our object PS1-10ah. However, the
rest of our objects seem to decline at a slower rate. One
possible explanation in that a larger fraction of the outer
envelope of these stars remain, leading to a longer recombination timescale (in their model of SN 1993J Woosley
et al. 1994 only invoke a 0.2 M! hydrogen envelope). We
also note that although many transients with bright cooling envelope emission are Type IIb SN, with a portion
of their hydrogen envelopes remaining, Kleiser & Kasen
(2014) has also modeled the Type Ic SN 2010X with the
main power source being oxygen, not hydrogen, recombination.
One important note regarding this as a possible power
source for our objects is the obvious lack of a second peak
due to the radioactive decay. In SN 1993J, a second peak,
of nearly the same peak magnitude in the visual bands,
was present ∼20 days after the explosion (Lewis & Walton 1994; Wheeler et al. 1993). This second peak is consistent with one powered by ∼0.07 M! of 56 Ni (Woosley
et al. 1994). As discussed above, no such obvious second
peak is evident in our transients. For instance, although
PS1-10ah shows a similar initial decline to SN 1993J we
can restrict the amount of Nickel powering a later peak
Shock break out from an extended stellar envelope
Shock break out from an dense CSM
c.f. Type IIn PTF09uj; Ofek+2010
Type Ibn SN1999cq Matheson+2000
Type Ibn SN2015U Shivvers+2016
Winds/outflows from compact objects/accretion discs
Fig. 19.— A comparison of the light curves of several of our
objects to two events from the literature thought to be powered by
varieties of shock break-out/cooling envelope emission. PS1-10ah
shows a similar initial decline rate to the Type IIb SN 1993J, but
has a consecutive lack of a later peak powered by radioactive decay.
PS1-11qr, PS1-12bv, and a number of our other more luminous
events are very similar to PTF09uj, which was hypothesized to be
due to the shock break out from an optically thick wind (Ofek et al.
2010)
Drout, M. R. et al. (2014)
Rapid Transients from PS1
Implications for Progenitors
The properties of many of PS1 objects are more consistent with being powered by
interaction and/or shock break-out
and recombination than by radioactive
decay
FBOTs
15
a massive star. While the shock break out from a massive star lasts only a matter of seconds (WR stars) to
hours (RSG) the process shock heats the ejecta which
then cools and recombines, giving rise to optical emission
Fast Luminous Blue Transient
which is independent
from later emission powered by the
decay of radioactive elements. For instance, the Type IIb
SN 1993J showed an initial peak which declined ∼1 mag
in ∼5 days which is attributed to such cooling envelope
Fallback Disk Outflow
emission. In Figure 19 we compare the light-curve
of
SN 1993J to several of our gold sample objects. We see
that the initial decline of SN 1993J is well matched to
the initial decline of our object PS1-10ah. However, the
rest
our objects
The of
outermost
layers haveseem to decline at a slower rate. One
possible
explanation
sufficient angular
momentumin that a larger fraction of the outer
envelope
of these stars remain, leading to a longer recomto form a disk.
bination timescale (in their model of SN 1993J Woosley
et al. 1994 only invoke a 0.2 M! hydrogen envelope). We
also note that although many transients with bright cooling envelope emission are Type IIb SN, with a portion
of their hydrogen envelopes remaining, Kleiser & Kasen
(2014) has also modeled the Type Ic SN 2010X with the
main power source being oxygen, not hydrogen, recombination.
One important note regarding this as a possible power
source for our objects is the obvious lack of a second peak
due to the radioactive decay. In SN 1993J, a second peak,
of nearly the same peak magnitude in the visual bands,
was present ∼20 days after the explosion (Lewis & Walton 1994; Wheeler et al. 1993). This second peak is consistent with one powered by ∼0.07 M! of 56 Ni (Woosley
et al. 1994). As discussed above, no such obvious second
peak is evident in our transients. For instance, although
PS1-10ah shows a similar initial decline to SN 1993J we
can restrict the amount of Nickel powering a later peak
Shock break out from an extended stellar envelope
Shock break out from an dense CSM
c.f. Type IIn PTF09uj; Ofek+2010
Type Ibn SN1999cq Matheson+2000
Type Ibn SN2015U Shivvers+2016
Winds/outflows from compact objects/accretion discs
The Inner core is directly swallowed
by the central black hole.
(Kashiyama & Quataert 2015)
Fig. 19.— A comparison of the light curves of several of our
objects to two events from the literature thought to be powered by
varieties of shock break-out/cooling envelope emission. PS1-10ah
shows a similar initial decline rate to the Type IIb SN 1993J, but
has a consecutive lack of a later peak powered by radioactive decay.
PS1-11qr, PS1-12bv, and a number of our other more luminous
events are very similar to PTF09uj, which was hypothesized to be
due to the shock break out from an optically thick wind (Ofek et al.
2010)
Rapid Transients from PS1
PS1 Rapidly-Evolving Transients
Detection Efficiency & Intrinsic Rates
RateFig.
of blue,
luminous events are approx 5500-8000 events/Gpc3/year
19.— PS1-MDS rapid-transient detection efficiencies for our
(4-7%
of the core-collapse
rateindicate
at z=0.2;
Botticella
et al. 2008)
rate
calculation.
Solid lines
detection
efficiencies
for individual PS1-MDS fields as a function of redshift (bottom axis)
or luminosity distance (top axis). A black solid line
indicates
Drout,
M.theR.
detection efficiencies for the survey as a whole, which peak around
11% at z=0.1. The dashed black line indicates the distance at
which we expect our detections to be located. This peaks at z=0.2.
et
2013) to calculate
MDS field can rec
distance.
We begin by con
evolution template
ure 1). We then c
consists of an intri
an exponential fun
sorption. In follo
adopt P(AV ) ∝ eA
for the host galaxy
intrinsic distributi
mean and variance
of our gold sample
for the Malmquist
Monte Carlo simul
from this distribut
apparent magnitud
detection limit (a
well with our obser
distance. The nom
gaussian distributi
al.
and(2014)
σ = 1.0 mag.
For each PS1-M
tion efficiency with
The Astrophysical Journal, 819:35 (22pp), 2016 March 1
Arcavi et al.
New and Related Transients
Table 6
Light Curve Parameters for our Events (the Explosion and Peak Dates are in the Observed frame, While Rise Times are in the Rest Frame)
Object
PTF10iam
SNLS04D4ec
SNLS05D2bk
SNLS06D1hc
texp
(MJD)
tpeak
(MJD)
Mpeak
trise
(days)
te
(days)
55342.24±0.14
>53180.60
>53375.58
>54039.34
55353.38±0.06
53196.58
53385.55
54056.36
−20.16±0.01
−20.33±0.06
−20.34±0.02
−20.22±0.03
10.05±0.15
< 10.03
< 5.87
< 10.95
2.53±0.38
1.95±0.88
2.76±1.79
3.62±2.12
1.  SN2015U (Type Ibn; Shivvers+2016)
Peak Lbol
(1043 erg s−1)
7.51
4.52
6.06
4.90
2.43
1.28
0.90
0.78
0.69
0.43
0.38
0.53
2.  Rapidly-Rising Transients in the SN-SLSN gap (Arcavi+2016)
Note. Peak magnitudes refer to R band for PTF10iam, z band for SNSL04D4ec, and i band for SNLS05D2bk and SNLS06D1hc. Bolometric luminosities are based
on blackbody fits (to a spectrum of PTF10iam and to multi-band photometry of the SNLS events). Errors and confidence bounds denote 1σ uncertainties.
Figure 8. Peak magnitude vs. rise time of our events (upper limits for the SNLS rise times) compared to other SNe (see text for references). All comparison data peak
magnitudes and rise times are in the observed R or r band. Rise times are in the rest frame of each event. Ejecta mass estimates are normalized to an expansion velocity
of 10,000 km s−1 (see text for details, also regarding the calculated nickel masses) and should only be considered approximate. Our events have shorter rise times
compared to most SNe and are more luminous than all similarly rapid events except for Dougie, which is a clear outlier in this context. The only event similar to ours
is SN 2011kl, which was accompanied by an ultra-long-duration GRB (Greiner et al. 2015). The positions of our events in this phase space require either a very high
New and Related Transients
1.  SN2015U (Type Ibn; Shivvers+2016)
2.  Rapidly-Rising Transients in the SN-SLSN gap (Arcavi+2016)
The Astrophysical Journal, 819:5 (15pp), 2016 March 1
3.  Rapidly-Rising Transients from Subaru Hyper Suprime-Cam
Tanaka et al.
(Tanaka+2016)
Figure 9. Summary of absolute magnitudes and rising timescale (τrise≡1/ ∣ m t∣) of transients. Our samples are compared with the following objects: SN 2010aq
and PS1-13arp (Gezari et al. 2010, 2015) with early UV detection with GALEX, the early peak of SN 2006aj (Campana et al. 2006; Šimon et al. 2010, Figure 6), SN Ia
2011fe (Brown et al. 2012), core-collapse SNe (SN Ib 2007Y, SN IIb 2008ax, and SN IIn 2011ht, Pritchard et al. 2014), and rapid transients from PS1 (Drout et al.
Rapidly Evolving Transients:
Future Directions
PS1 Rapidly-Evolving Transients
1.  Large Sample Sizes
Fig. 19.— PS1-MDS rapid-transient detection efficiencies for our
rate calculation. Solid lines indicate detection efficiencies for individual PS1-MDS fields as a function of redshift (bottom axis)
2013) to calculate
MDS field can rec
distance.
We begin by con
evolution template
ure 1). We then c
consists of an intri
an exponential fun
sorption. In follo
adopt P(AV ) ∝ eA
for the host galaxy
intrinsic distributi
mean and variance
of our gold sample
for the Malmquist
Monte Carlo simul
from this distribut
apparent magnitud
detection limit (a
well with our obser
distance. The nom
Rapidly Evolving Transients:
Future Directions
1.  Large Sample Sizes
2
2. Multi-wavelength and late-time follow-up
Postdoctoral Fellowship – Research Interests
le versus luminosity phase space for SN explosions. Red stars (highlighted region) represent
t prevalent, rapidly-evolving transients. Right: A template R-band light curve of one class
Thank You