1. Wide field X (& UV ?) Identify transients, distribute alerts Candidate X (&UV)-transients SN breakouts XRF ’ s LL GRBs Unknown (eg BH-Stellar disruptions)?

2. Early SN emission SN shock is radiation mediated at the envelope Outer (10 -3 M sun ) heated to ~keV Shock emergence accompanied by thermal X-rays Post breakout expansion  early UV emission Wind - Breakout may take place within the wind - Ejecta/wind interaction  non-thermal X, radio

3. Breakout X-rays: a simple model At  =c/v s : Optically thick wind,  ~1 breakout: E X, T  R, v s ; Consistency:  t~R/c. Ejecta/Wind Non-T X-rays:

4. XRO 080109-SN 2008D XRO: E X ~3x10 46 erg, R~c  t~10 12 cm (   ~1) R * ~10 11 cm  Wind, m dot ~few. Late non-T X (L X ~10 40 t d -0.7 erg/s)+ radio  m dot ~1 (@ 10 15 cm) wind + 10 47 erg,  ~0.3 shell T=0.1keV? No! Non-thermal, dlog n  /dlog E  ~ -2 Jets? Or- Non-LTE X-rays in fast (v/c>0.1) breakouts: [Kat & Budnik 10]

5. Some implications XRO 080109 may be SN 2008D breakout For reasonable explosion parameters, WR & BSG progenitors produce fast breakouts  non-thermal XRO ’ s up to 10 ’ s to 100 ’ s keV New type of SN trigger Accurate timing (hr  models,, GW) E X, T  R, v s LL-SN-GRBs: E  ~10 49 erg, h <300keV, smooth L(t) – Jets or E K ~10 49.5 erg,  ~0.8 breakouts? Consistent with properties of 980425/SN1998b, 031203/SN2003lw, 060218/SN2006aj; 98bw late radio + X: now jet, E K ~10 49.5 erg,  ~0.8 shell; Challenges: E K (  ~0.8)/E K,tot ~10 -2 [Anisotropy, Failed Jet?].

6. X-ray: fluxes & rates 50SN/yr to 30Mpc SN BO ’ s:  dist. not known  Lower threshold E? 08D based rate (95%) > 10 -3 /L * yr~0.1 CC SN rate LL GRBs: E X ~10 48.5 erg (??) ~10 -5 /L * yr~1/yr out to 100Mpc ~10keV XRF ’ s: E X >~10 48 erg (??) ~10 -6 /L * yr~ 0.1/yr out to 100Mpc ?? MBH Stellar disr.: 0.01M sun c 2, 10 5 (M/10 8 M sun )s  10 47 erg/s

7. X-ray: Detectors Required:  ~ 1 f < 10 -9 erg/s (~10s)  ~ follow up FOV

8. The UFFO Pathfinder arXiv:0912.0773

9. Summary- X Identify transients, distribute alerts Required:  ~ 1, f < 10 -9 erg/s (~10s),  ~ follow up FOV Candidate X (&UV)-transients * SN breakouts: New SN trigger, Accurate timing (hr  models,, GW); E X, T  R, v s * XRF ’ s, LL GRBs: Sources, SN-connection, physics * Unknown (eg BH-Stellar disruptions)

10. UV transients Best resource is GALEX, not systematically surveyed so far Two classes of events receive attention: UV shock breakouts and tidal disruption flares Contamination by stars and AGN is a major issue

11. Early UV/Optical emission Rapid post-breakout expansion  Adiabatic cooling, photosphere penetration t>R * /v BO Predictions: Measure R ( from T), E K (@  m/M~0.003) Complications: Extinction, opacity E.g. No of H  recombination @ 1eV  Constrain envelope composition

12. 2008D: Determine R * & Reddening Scaling t, f  : [Rabinak 10]

13. 2008D- UV summary Early UV/O: R * =10 11 cm, He with C/O Relative extinction curve, E B-V =0.6 E 51 /(M/M sun )~0.8 (assuming A V (E B-V )) Later light curve: 0.8<E/M<1.3 ~30% C at 20,000km/s 0.4<E B-V <0.8 Progenitor models: 0.9<R * /10 11 cm <1.5 [Rabinak 10] [Mazzali et al. 08, Tanaka et al. 09] [Mazzali, priv. comm.] [Soderberg et al. 08] [Tanaka et al. 09] [Modjz et al. 09] UV/O model [Tanaka et al. 09]

14. UV breakout rates (based on Gezari 2008, GALEX) GALEX expected rate (optimistic?) is 2 deg -1 y -1 If we scale the GALEX area by ~10 3, we can expect >10 events y -1 even if the sensitivity is 10 2 less. The observed signals have UV flux~host, so confusion with (even mildly) variable sources is an issue unless additional information is available A combined UV survey+optical SN survey like PTF will be powerful to get retrospective measurements

15. Tidal disruption flares A star disrupted and accreted by a dormant supermassive black hole is expected to result in a UV/X flare, several months long. Several events claimed based on wide-field X (ROSAT) and UV (GALEX) Major issue is confusion with AGN.

16. UVFs Speculative: the end of the GRB-XRF sequence would be very soft flares (UVFs). Here, and in all other “unknowns” confusion with stars and AGN is a formidable obstacle.

17. UV - summary Best resource is GALEX, not systematically surveyed so far, most parameters unknown UV shock breakouts should be accessible to wide- field, moderately sensitive instruments Combination with X or optical may be powerful Contamination by stars and AGN is a major issue