Transcript p of the Sky

„Particle physics and cosmology: the interface”
3.5.2006, Warsaw
Search for optical flashes
of astrophysical origin
with „p of the Sky” experiment
• Gamma Ray Bursts as standard candles
• Very short GRB and primordial black holes
• GRB optical emission
• Experiment „p of the Sky”
Grzegorz Wrochna
Soltan Institute for Nuclear Studies, Warsaw
grb.fuw.edu.pl
1
GRB as a tool for cosmology

Cosmology became experimental science
Universe space-time properties measured using
supernovae as standard candles up to z = 0.97

Gamma Ray Bursts may become more powerful standard
candles


The farest GRB observed has z = 6.2 !
2
Gamma Ray Bursts - GRB
(0.01-100s) g–ray pulses
 From pointlike sources in the sky
 Brighter than the rest of the sky (in g-rays)
 Energy 1051 erg (=1010 years of Sun emission)
 Distance up to z=6.2
 Frequency 2-3 per day
 Discovered in 1967 by military satellites VELA
 So far >3000 observed
including ~100 in visible light
distance measured for ~70
 Observed in radio waves, X-rays, g ~GeV,TeV
 Short
3
Izotropic distribution in galactic coordinates
4
GRB spectrum
GRB 980329
νa
radio
afterglow
10 GeV
cooling
self absorption
synchrotron absorption
Fm
νm
GRB 940212
νc
optical
X-ray
5
Different
shapes
Time:
0.01-100s
6
„Short” and „long” bursts
7
Mechanizm błysków gamma
8
Anisotrophy of very short (<0.1s) GRB?
Cline, Matthey, Otwinowski
astro-ph/9905346
astro-ph/0510309
Primordial black
holes?
9
V. short GRB / CMB correlation?!
Colour map – CMB (WMAP) / GeV g (EGRET) correlations
Wibig, Wolfendale, astro-ph/040939
10
Swift GRB 2004.12.19
Precursor seen also in GRB 2005.01.24 and some others
B.Paczyński and P.Haensel (astro-ph/0502297)
interpret prekursor as a collaps to a neutron star
and the main burst as creation of a quark star
11
GRB’s today and tomorrow
Today:
 gamma emission well understood
 central engine(s) still uncertain
Tomorrow:
 coincidence with TeV photons, neutrinos, etc
 optical observations before and during GRB
 using GRB as standard candles for cosmology
12
Sakamoto et al., 2003
Isotropic energy [erg]
Isotropic luminosity [1051erg/s]
E peak [keV]
GRB as standard candles
Reichart et al., 2001
Hardness [ch1-ch3]
Cepheides-like correlations might allow us to study
the Universe much farther than Supernovae
13
If in M31 (Andromeda)
 brighter than the Moon
If in M42 (Orion nebula)
 brighter than the Sun!
Egamma > 104x Evisible
GRB releases
energy
>1051 erg = 1044J
in 0.1-100s
The same will be released
by the Sun oven its all life
(1010 years)
14
BATSE & ROTSE
4 telephoto lenses
CANON d=10 cm
robotic mount
follows GCN alerts
Images 1999.01.23
20 s after BATSE alert
Optical flash 9m !
could be seen by binocular!
The brightest so far
15
1 min. – 10 cm photolenses
1 h – 30 cm amateur telescope
1 day – 1 m professional telescope
1 week – 6 m giant telescope
1 month – Hubble telescope
16
Catching prompt optical emission
No one knows were the next GRB will happen
Standard approach:
 wait for GRB alert and move there quickly


robotic telescopes listening to GCN:
BOOTES, (SUPER)LOTIS, MASTER, RAPTOR, REM,
ROTSE, TAROT, ...
New approach needed:
 look everywhere, all the time
 wide field of view (p steradians ?)

self-triggering
 experiment „p of the Sky”
17
„p of the Sky” - grb.fuw.edu.pl
Design:
• continuous ~all sky survey (32×3000 images / night)
• large data stream ( 1 Terabyte / night)
• real time analysis
• multilevel trigger
• under construction (ready by fall 2006)
Prototype:
• 2×16 CCD cameras, each 2000×2000 pixels
• Canon lenses f=85mm, f/d=1.2
• field of view = 2 steradians = Swift BAT
• works from July 2004 in Chile
Collaboration:
• Soltan Institute for Nuclear Studies, Warsaw
• Center for Theoretical Physics PAS, Warsaw
• Warsaw University
• Warsaw University of Technology
18
„p of the Sky” prototype
• 2 CCD cameras 2000×2000 pixels
• common field of view 33°×33°
• 32 cameras under construction
Las Campanas Observatory, Chile, from 7.2004
Tests in Poland
• robotic mount
• < 1 min. to any point
in the sky
http://grb.fuw.edu.pl
19
„p of the Sky”: robotic detector
Autonomic operation according to programme:
• follows HETE or INTEGRAL field of view
• detects itself optical flashes
• all sky survey twice a night (2×20min)
• follows targets of GCN alerts
High reliability:
• remote-reset, Wake-on-LAN, Boot-from-LAN
• selfdiagnostics (e-mail and SMS to Poland)
During one year of operation:
• ~10 nights lost due to apparatus problems
+ ~30 nights lost due to weather
• > 300 „good” nights, 1 000 000 sky images,
1010 photometric measurements
20
Flash recognition in real time
multilevel trigger concept (a’la particle physics exp.)
all pixels
One night
coincidence
stars
bad pixels
cosmics
planes
satellites
21
„p of the Sky”: GRB observations
89 GRB’s discovered by satellites 7.2004-7.2005:
5 – clouds (4) or apparatus off (1)
18 – Northen hemisphere
48 – daytime or below horizon
16 – outside field of view, 4 limits better than others
GRB 040916B, >13m for t > t0+17min (publ. GCN 2725)
GRB 041217, >11.5m for t > t0+30min (publ. GCN 2862)
GRB 050123, >12m for t < t0-108min (publ. GCN 2970)
GRB 050326, >11m for t < t0-33min (publ. GCN 3146)
2 – within FOV: GRB 040825A (published: GCN 2677)
>10m for t < t0-11s
limits before
>12m for t = t0
and during GRB
m
>9.5 for t > t0+7s
GRB 050412 (GCN 3240) >11.5m / >11m / >11.5m
22
Search for cosmic flashes




„p of the Sky” prototype at LCO, July 2004 – July 2005
~100 flashes seen by both cameras, in one frame only
(could be satellites reflecting sunlight)
6 flashes seen in >1 frame (not confirmed/excluded by others)
1 flash identified as CN Leo flare star outburst
Several slower star-flares detected off-line
CN Leo
EQ Peg
23
„p of the Sky” general goal:
study objects varying on scales from seconds to months
Examples of night-life of stars - brightness vs time (one night)
24
GRB optical
observations
measurements
Very few points <20s
after GRB t0
dashed line – „p of the Sky”
range
dotted line – filter corrected
limits
25
Prompt optical
GRB observations
„p of the Sky” is
optimized for t < t0 + 60 s

filter corrected limit
„p of the Sky” limit
prototype limit
Observed by other
experiments
Only 14 measurements
by other experiments
exist in this range

Extrapolation to 30s
from later time suggest,
that „p of the Sky” will
see ~1/4 of visible GRB

Extrapolated from
later mesurements
26
27
grb.fuw.edu.pl
p of the Sky