The Mysterious Connection between Superluminous Supernovae and Gamma-Ray Bursts STScI Mon, May 23, 2016 11:04 AM Raffaella Margutti: Fate of jets trying to break through progenitor envelopes create explosion, put inside stellar envelope, see what happens start with massive star H envelope surrounding core sometimes H envelope is gone - we see SNe Type I see graph of kinetic energy vs. gamma-ray beaming prediction of hydrodynamic collapse is slope -5.2 in general, slope is always steep for spherical collapse monitor in optical -- shows slow-moving thermal emission monitor in radio -- shows fast-moving shocked non-thermal emission so multiwavelength obs can help us put events on this diagram shows results: ordinary SNe Ibc (stripped envelopes) slopes are close to -5.2 velocites typically non-rel SN-GRBs show much smaller slopes slopes close to -0.5 or -1.0 material is in relativistic regime difference: SN-GRBs put much more energy at high speeds than ordinary SNe ordinary: non-collimated, non-rel SN-GRB: collimated, rel so, a matter of how the energy is partioned in explosion but some events lie between the groups 12ap, 09bb less energetic than GRB, mildly relativistic, less collimated slope around -2.4 10 times more common than GRB maybe has weak jet, barely escapes envelope radio luminosity vs. X-ray luminosity "middle" events are similar to ordinary SN in radio but not X-rays -- much weaker why does a jet fail to break out? shorter engine life-time or larger progenitor example: 2012ap _may_ show He so it had some envelope need better observations in other events multiwavelength and messenger optical: energetics of explosion, composition, environment radio: engine vs. no engine X-ray: breakout vs. no breakout neutrinos: extra info! supernovae: core-collapse events: 70% type Ic 20% of these BL-Ic 5% of these relativistic ejecta 10-20% of these fully-rel 10% of these what about SLSNe-I? some SLSNe may have rel jets radio campaign to look for them VLA obs of PS15ae = SN 15bn, redshift 0.1 upper limits of radio obs place limits on jets but we can't put limits on low-lum GRBs need very early obs with VLA or other radio telescopes jets may be ubiquitous SN remnants in MW show evidence for jets Cas A - clearly asymmetric W49B may show evidence for jets Take-away list: 1. energy partitioning 2. continuum of explosions, non-rel to rel 3. Sub-E GRBs and Rel-SNe are intrinsically different explosions 11:24 AM Q: are you saying the mass ejected is approx same for all types? A: yes, roughly Q: what about partially failed events? A: more energy than usual Q: Do you have more examples of partially failed events? A: yes, didn't have time to include here the environment can mask detections Q: how do you get 10^(52) ergs without an engine? A: there can be engines we don't detect Q: samples of SNe are selected in different ways, is important A: yes, very true. Selection effects are important, the "middle" group is hard to find Q: is there a relationship between remnant types and your classes? A: I'd prefer not to say 11:29 AM: Kunta Misra: Radioactive decays of GRB-SNe at late times GRB-SN association GRBs assoc with broad-lined Type Ic high ejecta velocities 30,000 km/s optical spectrum at first featureless after some weeks, lines come up in prominence 2003dh and 2006aj SNe assoc with GRBs/X-ray flares both observed with HST at very late times, 300 days unusual to see so late 1998bw and XRF 020903/SN, 2010bh are a few others 2006aj assoc with XRF 060218, z = 0.033 shows ground-based light curves, with HST points at late times fit late-time curves with power law to estimate decay rate slopes are STEEPER than 56Co - 56Fe decay rate (0.0098 mag/day) some leakage of gamma-rays late-time luminosity of 2006aj is 2x smaller than 1998bw suggests a factor of 2 smaller mass of ejected 56Ni look at 56Ni mass estimates of Type Ic SNe 12 events 4 with SN Ic/GRB 5 with broad-line Ic only 3 with ordinary Ic heterogeneous group in mass of 56Ni late-time I-band light curves of these shows all of them have similar slope in I-band decay rate hmmm if scale light curves via ejected mass of 56Ni, the light curves are very similar this is NOT true in the B-band light curves not so similar in luminosity after scaling offsets between events by factors of 3 or so results - suggests that light curves of GRB-SNe are powered throughout by radioactive decay of 56Ni (even though jets may exist) 11:41 AM Q: this is very interesting. Escape of gamma rays depend on density of the ejecta, so ejecta has similar density? Interesting A: yes Q: the evolution of leakage must also be similar A: yes. but observations are difficult Q: bolometric light curve is more similar than the B-band so perhaps effects of different ions from particular elements A: iron lines are most important, probably bolometric light curves are hard to make, requires multi-passband obs very few are available Q: B-band contribution at late time? A: at late times, very small; I is more important Q: do you have Ic events without GRBs? A: yes, and their properties are similar Q: we published a paper showing big diversity among different types A: we only look at Ic 11:45 AM: Avishai Gilkis: Jet Feedback Mechanism Mechanism 1. central engine launches jets 2. jets deposit energy in core, then ejecta 3. engine shuts down when jets remove core material this is a NEGATIVE feedback mechanism all or most of core-collapse SNe explosions are powered by jets efficiency high-effiency feedback core material ejected accretion halts quickly regular energy SN low-efficiency core material persists accretion continues jets last longer, supply more energy why diff efficiency? change in jet axis? relative motion of core material (due to convection) rapid pre-collapse core rotation basic picture accretion disk around NS/BH core material accel by jets energy deposited in ejecta grav potential energy reduced reduction in grav potential can be parameterized in terms of gamma made models with different jet efficiency in expelling mass must account for loss of mass/energy by neutrinos - approx 0.2 solar mass late fall-back is possible for material to be pushed out by jet, but fail to escape can then later fall back, power later luminosity hundreds or thousands of seconds could high core rotation reduce feedback efficiency? shows movies based on models mag fields around collapsing rotating star shear and turbulence around proto-NS are important magnetars to make one, need high ang mom in core newborn magnetic in rotating accretion structure likely to produce jets as well predictions - SN asymmetry correlates with explosion energy more energy -> more asymmetry - some material does not fall back -> slow outflow in equatorial plane - continued accretion -> higher remnant mass for energetic SNe 11:57 AM Q: can a kick to compact remnant also quench a jet? A: I didn't consider that Q: some stars might not have enough rotation to make a jet A: I'm not sure that there's a requirement for rotation of pre-collapse star in order to form a jet convection can complicate this Q: what fraction of stellar binding energy is ejected in form of jet? A: varies depending on details Q: do you expect most energetic explosions will create BH instead of NS? A: yes 12:00 noon: Andy Howell: Rapidly rising transients and connection with GRBs LCOGT is a global telescope network of robotic telescopes Hawaii, Australia, plus others can request observations, automatically made Wyse Obs just joined 2 new telescopes will go in Tibet soon plan to put high-res spectrographs on some telescopes Wolf studied 1500 high-z light curves of transients got spectra of 2 SLSNe found about 20 SLSNe overall, fit blackbody to data discovered high-luminosity, fast-rising light curves rise in less than 10 days U-band abs mag < -19 see poster at this meeting Arcavi was looking for TDEs in PTF data found a fast-rising event at z = 0.1, PTF 10iam spectra show blue continuum then evolves normalish SN features if fit to Type II does show broad H-alpha emission but only high-velocity H-alpha absorption if fit to Type Ia other peculiarities GRB 111209A connected to SN 2011kl , z = 0.677 rise in about 10 days light curve similar to some studied by Wolf and Arcavi can make graph abs mag vs. rise time normal SNe, SLSNe, and these fast-risers fall in different locations no gamma-rays seen, but Fermi satellite wasn't always looking Swift BAT doesn't see whole sky what are these fast-risers? 1. 56Ni powers the light curve but rise seems too fast in these new events 2. circumstellar interaction but spectrum doesn't have typical narrow lines and again rise is too fast in these new events 3. shock breakout in a wind but time evolution is not correct 4. magnetar powers it but need extreme values of mass (2 Msolar) and rotation period (2 ms) and still can't reproduce light curve well conclusions - found a new class of fast-rising transients they may not all be related 12:14 PM Q: what about your selection cuts in picking events to study? A: I think we should have included some fast-rising ordinary SNe, but this is a good question Q: what about the host galaxies of these objects? A: star-forming hosts, emission lines, sorta high-redshift alas consistentish with GRB hosts Q: what about the spectra of these events? A: shows example of one event 111209A, pretty noisy, hard to interpret Q: how do rates compare to other types of explosions? A: it's tricky to compute, we didn't really do it PTF doesn't provide many rates, so hard to say not a really big rate Q: on rates, is anyone going to present a talk here about that? (Tanvir): depends strongly on redshift, extrapolation of lum function Q: it's easier for a magnetar's jet to escape from small-mass envelope Q: small samples A: yes, very hard to find them before peak, they rise so fast (comment) metallicity of these tend to be high-ish, solar-ish 12:21 PM break for lunch