Download X-ray and UV Transients

Wide field X (& UV ?)
Identify transients, distribute alerts
Candidate X (&UV)-transients
• SN breakouts
• XRF’s
• LL GRBs
• Unknown (eg BH-Stellar disruptions)?
Early SN emission
• SN shock is radiation mediated at the envelope
• Outer (10-3Msun) 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
Breakout X-rays: a simple model
• At t=c/vs:
b s,max  v s,max / c  0.2
EBO  2 10 46
E 510.6
M / M Sun 0.4
E 510.6
M / M Sun 
0.4
R120.3 ,
1.7
R12
erg, TBO  0.2
E 510.2
M / M Sun 
0.05
R120.5 keV.
• Optically thick wind, Gb~1 breakout:
EBO  3 1046 Gb  R122 erg, TBO  0.1Gb  R121/ 4 keV.
4
3
• EX, T  R, vs ;
Consistency: Dt~R/c.
• Ejecta/Wind Non-T X-rays:
L IC,syn  10
40

 min 
e , 1
1/ 3
e , 1
LSN , 42 , t day

Ek , 47 erg
.
2/3
t day s
XRO 080109-SN 2008D
•
XRO: EX~3x1046erg, R~cDt~1012cm (Gb~1)
R*~1011cm  Wind, mdot~few.
• Late non-T X (LX~1040td-0.7erg/s)+ radio
 mdot~1 (@ 1015cm) wind + 1047erg, b~0.3 shell
• T=0.1keV? No! Non-thermal, dlog ng/dlog Eg~ -2
• Jets?
Or- Non-LTE X-rays in fast (v/c>0.1) breakouts:
b s,max  vs,max / c  0.2
E 510.6
M / M Sun 
0.4
R120.3 ,
TBO,s  10( b s,max / 0.2) 4 keV.
[Kat & Budnik 10]
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)
EX, T  R, vs
LL-SN-GRBs: Eg~1049erg, h<300keV, smooth L(t)–
Jets or EK~1049.5 erg, b~0.8 breakouts?
Consistent with properties of
980425/SN1998b, 031203/SN2003lw, 060218/SN2006aj;
98bw late radio + X: now jet, EK~1049.5 erg, b~0.8 shell;
Challenges: EK(b~0.8)/EK,tot~10-2 [Anisotropy, Failed Jet?].
X-ray: fluxes & rates
• 50SN/yr to 30Mpc
• SN BO’s: EX, BO  1046 erg,
f X, BO  10
8.5
R120.7
erg/s,
2
D30
TBO,s  10( b s,max / 0.2) 4 keV.
b dist. not known  Lower threshold E?
08D based rate (95%) > 10-3/L*yr~0.1 CC SN rate
• LL GRBs: EX~1048.5erg
(??) ~10-5/L*yr~1/yr out to 100Mpc
• ~10keV XRF’s: EX>~1048erg
(??) ~10-6/L*yr~ 0.1/yr out to 100Mpc
• ?? MBH Stellar disr.:
0.01Msunc2, 105(M/108Msun)s  1047erg/s
R / c  30 R12 s,
X-ray: Detectors
Required:
• DW ~ 1
• f < 10-9 erg/s (~10s)
• Dq ~ follow up FOV
The UFFO Pathfinder
arXiv:0912.0773
Summary- X
• Identify transients, distribute alerts
Required: DW ~ 1, f < 10-9 erg/s (~10s), Dq ~ follow up FOV
• Candidate X (&UV)-transients
* SN breakouts: New SN trigger,
Accurate timing (hr  models, , GW);
EX, T  R, vs
* XRF’s, LL GRBs: Sources, SN-connection, physics
* Unknown (eg BH-Stellar disruptions)
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
Early UV/Optical emission
• Rapid post-breakout expansion
 Adiabatic cooling, photosphere penetration
• t>R*/vBO Predictions:
Teff.  1 T / m p 
0.27
1/ 4 -1/2
R12
tday eV,
Lbol. ~ 1042  T / m p 
0.8
E 510.9
M / M Sun 0.7
-1/3
R12tday
erg/s,
f UV ~ 1011
• Measure R ( from T), EK (@ dm/M~0.003)
• Complications: Extinction, opacity
E.g. No of H  recombination @ 1eV
 Constrain envelope composition
R12
erg/cm 2s
2
D30Mpc
2008D: Determine R* & Reddening
Scaling t, fl :
[Rabinak 10]
lTcol.[t  tl (t , l )]  l0Tcol. (t )
 D 
~
f l [l , tl (t , l )]  

 rphot. 
2
 Tcol. (tl ) 


 Tphot.(tl ) 
4
5
 T0 
t l
f
(
l
,
t
)

F
(
t
)
e
l

 l
T
(
t
)
 col. l 
2008D- UV summary
• Early UV/O: R*=1011cm,
He with C/O
Relative extinction curve, EB-V=0.6
E51/(M/Msun)~0.8 (assuming AV (EB-V))
[Rabinak 10]
• Later light curve:
0.8<E/M<1.3
~30% C at 20,000km/s
0.4<EB-V<0.8
Progenitor models:
0.9<R*/1011cm <1.5
[Mazzali et al. 08, Tanaka et al. 09]
[Mazzali, priv. comm.]
UV/O model
[Tanaka et al. 09]
[Soderberg et al. 08]
[Tanaka et al. 09]
[Modjz et al. 09]
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 ~103, we can expect
>10 events y-1 even if the sensitivity is 102 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
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.
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.
UV - summary
• Best resource is GALEX, not systematically
surveyed so far, most parameters unknown
• UV shock breakouts should be accessible to widefield, moderately sensitive instruments
• Combination with X or optical may be powerful
• Contamination by stars and AGN is a major issue