Transcript SNEWS

SNEWS –
The Supernova Early Warning System
But star is transparent to n within ms after the
formation of the neutron star
Light from a core-collapse Supernova
will not escape from star until the
shock wave breaks out through the photosphere.
Many n experiments sensitive to n from
nearby SN (in our galaxy)
Super-Kamiokande
(Japan) 50kton
LVD (Italy) 1kton
Liquid scint ~300 ne
7000 inv. b decay, 410 on 16O,
300 elast. scattering, 4o pointing
SN 1987A was seen
by previous expts.
so n precede photons by the time it takes the
shock to traverse the radius of the star, hours
of advance notice of the impending SN – if
you can see the n
<Ene> ~ 12 MeV
<Ene> ~ 15 MeV
<Enm> ~ 18 MeV
(expected rates below for [email protected] kpc)
Alec Habig, UMD,
for the SNEWS group
Sudbury Neutrino Observatory
(Canada) 1.7kton H2O, 1kton D2O
710 inv. b decay, 160 2H breakup,
45 elast. scattering, 17o pointing
SNEWS is a coincidence network between these experiments’ own SN alarm
triggers
Goal – eliminate possible false alarms which occur in an individual experiment due
to local conditions
A real SN will be observed ~simultaneously in all!
Removing the need to have a shiftworker manually vette alarms allows automated,
fast alert to take advantage of n lead time
Will allow observation of the next nearby SN from times near zero
SSL sockets
Server
10s coincidence
window
PGP signed
HST Target of Opportunity time allocated, an example of a pre-prepared observing
plan to exploit this information
Coincidence server
securely hosted by
Brookhaven National Lab
email
AMANDA
(South Pole) 1.6kt ice/PMT, 667 PMTs
~16s singles rate increase
In final SNEWS test phase
Email alarms
to astronomers
and n experimenters
GCN alert
(coming soon!)
Sign up yourself to receive an
alert at: http://snews.bnl.gov/
Bonus – this existing collaboration between experiments allows the coordination of
downtime between experiments, to help ensure someone somewhere is live for
supernova at any given time
Bonus #2 – experiments can send “Gold”, no-doubt alarms, or “silver” alarms
which might have some problems (during calibration or maintenance runs, for
example).
•If a coincidence is formed due to “Silver” alarms, the alert does not go to the
world, but back to the experiments so the operators can verify things (and
upgrade to a Gold alarm if appropriate)
•This is some comfort to experimenters, after all Murphy’s Law says that the
next SN will come when you’re not ready for it
(Mini-BooNE, KamLAND, Borexino, LIGO
also sensitive to nearby SN but not yet
sending alarms to SNEWS)
How to pin down SN location?
Given that the best n pointing information is from elastic scattering, leaving a search field of
many square degrees at best, how will observers find the new Supernova to take advantage
of the early alert and get observations from the earliest possible epoch?
One avenue is high energy satellites with all-sky capability, a n alert will let them prepare.
Shock breakout should produce a strong UV/X-ray transient. SNEWS will tie into GCN soon
in order to make this easier.
Another – Amateur astronomers have many eyes, wide angle instruments, and intimate
knowledge of the sky
Sky & Telescope and the AAVSO have experience in coordinating amateur efforts
On Feb 14 2003, a carefully labeled test message was sent:
Looking for ~1 SN/century, cannot tolerate more false alarms than SNe
False Alarms are Poissonian, uncorrelated. If rate is at most 1/10days /expt,
(for 2 of 4 coincidence), above is the false coincidence rate
This Sky & Telescope AstroAlert is being issued [as a test] in support of the
SuperNova Early Warning System (SNEWS). We seek your assistance in pinpointing
the location of a possible supernova explosion. Neutrino detectors give the target‘s
approximate coordinates (equinox 2000.0) in the constellation Bootes, as follows:
Right ascension: 13h 38m
Declination:
+8.1 degrees
Uncertainty radius: 13 degrees
Expected magnitude: unknown
Please check this region of the sky as soon as possible using your naked eyes,
binoculars, a telescope, or a camera. You are looking for a starlike point of
light ...
•Vesta (mag 6.7) was at a stationary point in its retrograde loop in the given error box
–Not a regular star, not moving
•It worked, given the small statistics of those wishing to participate in a known test –
–~90 responses, all over the world, wide variety of instruments
–70% of people got the alert within 8 hours (a dozen right away)
–Given time of day and weather, many found Vesta, and had good search strategies
–Will do more such tests, for practice and to maintain interest
Summary
2001 “high rate test” using artificially lowered experimental thresholds
confirms Poissonian, uncorrelated nature of the alarms and coincidence
network
All alarm data normally kept confidential, internal to the SNEWS server
•SNEWS operational, waiting for galactic supernova
•Four participating experiments at present
•Adding others as their SN n triggers mature
•Sign up for your own once-per-career galactic supernova email alert:
•http://snews.bnl.gov
SNEWS supported by NSF grants
#0303196 and #0302166
•What would you do with ~hours warning of a supernova?
•See astro-ph/0406214 (New J.Phys. 6, 114) for far more details about SNEWS
than fit on a poster and references