About the discovery of X-ray bursts35 years ago
John Heise’s After Dinner speech
X-ray burst workshop
Leiden 2010
SRON-Utrecht
many high-energy satellites in the period 1960-1975
UHURU 1971
Vela-5 1969
SAS-3 1975
ANS 1974
1960 1975
Mostly “scanning” satellites
• small fraction of time “on source”• but seeing large fraction of the sky• rare phenomenae better seen while
pointing
• ANS, the Astronomical Netherlands Satellitethe first X-ray pointing satellite
ANS, 1974-1976, the first 3-axis stabilized X-ray satellite
• for X-ray & UV
• with unfavorable orbit:
ANS
Instruments:
SRON-Utrecht SXX 0.2 – 0.25 keV
1-7 keV
Harvard+MIT HXX 2-25 keV
bragg-crystal spectr.
Groningen UV-telescope
SXX: John Heise
HXX: Gursky, Grindlay
bragg: Schnopper,
X-ray bursts discovered for the wrong reasonNGC 6624, a centrally condensed
globular cluster
errorbox
3U1820-30
In 1974 thought
(Bahcall) to contain a
Central Black Hole of
~100-1000 Msun
characteristics of
BHs were thought to be
● soft spectrum
● variability
1974 Rothschild
et al.
~millisec bursts
(for ~1 Msun)
so possibly
Expecting
~sec bursts
(for ~1000 Msun)
In 1974: 1 candidate Black Hole: Cyg X-1exhibiting millisec bursts
summer 1974
(after visit John Bahcall)
Heise planned
observations
for 3U1820-30 around
28 september 1974
swapping time with
the UV-experiment t
maximize exposure time
with window
ANS planning:visibility per source ~1 day/cos(lat)
Data analysis nov 1975
35 years ago
nov 1975 discovery of 2 X-ray Bursts in 3U 1820-30
ANS-data
NGC6624
3U1820-30
ANS data arrived in nov 1975
Data reduction with
Josh Grindlay, Harvard:
Grindlay & Heise, 1975
(IAU-circular)
Grindlay et al, 1976
10 s
dec 1975: energy explosions in spaceDutch press:
sensational discovery with “ANS”
“ANS”
Astronomical Netherlands Satellite
1974-1976
main concern in the beginning:background particle events?
• SXX and HXX different respons
to high-energy particles
• collimators were slightly offset
and ratio was consistent
with celestial source
NO:
others were less concernedabout the possibility of bg-events
COSMOS 428
1960 1975
Background events?
Hard “bursts” seen everywhere since 1971! But these were background
Kosmos 428 satellite,
IKI, Moscow
Babushkina
Kudryavtsev
Melioranskii
Walter Lewin 1977:
correlated with geoposition
(all near van Allen belts)
Thermonuclear explanationof X-ray bursts
● 1975, Hansen and van Horn
“Nuclear fusion in accreting neutron star envelopes”
● 1976, first mentioned in the context of X-ray bursts
by Laura Maraschi (Milaan)
● 1976, Woosley and Taam
Thermonuclear explosions on Neutron Stars
● 1976, Jean Swank
BB emission size consistent with NS
What about the Vela-5A/B short transients?
Including the
“Norma burster”
position accuracy
~6 degree
Walter Lewin in reviews:
ignored by definition
(Def. : X-ray bursts have
rise times ~1 sec, not seen
in Vela-bursts)
Other Fast Transients in X-rays
● Other satellites (Ariel V etc) discovered
fast Transients also at high galactic latitude
● What is the nature of these sources?
some may be Gamma Ray Bursts
some may be related with flare stars
● The study required the use of wide field
imaging in X-rays with long exposure times:
just sit and wait till a transient occurred within the FOV
Wide Field Cameras in X-rays
To localize new fast Transients and establish there nature
SRON-Utrecht invested in Coded Mask Camera’s
Wide Field Cameras in X-rays1980 5 WFCs?
new Dutch satellite TIXTE?
TIXTE:S/C concept
WFC’s
WFC’s
1982 4 WFCs?
new ESA satellite X80?
1981 COMIS/TTM om MIR-station
a pilot study with 1 WFC? YES! Launched 1987
1983 3 WFCs?
Dutch-Italian satellite
1985 2 WFCs!
Dutch-Italian SAX satellite
biggest succes:arcmin localization of GRBs
Cyg X-1Burst
40o
40o
sign
ifica
nce→
exposure 52 ksec 30 sec 48 ksec
3ox3o 3ox3o 3ox3o
GRB960720
GRB970228
WFC
GRB
WFC view on the Galactic Center
discovery of new neutron stars
SAXJ1808-36
WFC discovery of superbursts a new thermonuclear burning regime
4U1735-44 Cornelisse et al. 2001
KS1731-26
X-r
ay
inte
nsi
ty →
har
dn
ess
→
E~1039 ergs
E~1042 ergs
X-ray
Burst
Superburst
Rön
tgen
-inte
nsite
it→
time →
Xray-burst publications per year
1976 1985 1995 2005
Tod’s discovery of
burst oscillations
data Jean in ‘t Zand
Top of most cited papers
Wallace & Woosley (1981): 372 (TH, Explosive hydrogen burning)
Lewin et al. (1993): 284 (Space Science Review)
Strohmayer et al (1996): 283 (OBS, Discovery burst oscillations)
Grindlay et al. (1976) 198 (OBS, discovery paper)
Lewin et al. (1981): 181 (Space Science Review)
Woosley & Taam (1976): 174 (TH, 1st interpretation)Fujimoto et al. (1981): 165 (TH, Accretion regimes for bursting)
Chakrabarty et al. (2003): 164 (OBS, burst.osc. pulsar in J1808)
Schatz et al. (2001): 158 (TH, endpoint of rp process)
Ayasli et al. (1982): 152 (TH)
Kuulkers et al. (2003): 125 (OBS, PRE bursts in Globular clusters)
Swank et al. (1977): 116 (BB emission size consistent with NS)
Joss et al. (1977): 107 (TH)
Strohmayer et al. (2002): 104 (OBS, Superburst from 4U 1820-30)
most productive authors
nr as first author (Citation score)
Lewin: 41 (20)
van Paradijs: 21 (23)
Strohmayer: 34 (29)
Grindlay: 15 (26)
in 't Zand: 14 (23)
Kuulkers: 13 (19)
Taam: 13 (23)
Swank: 10 (17)
Hoffman: 10 (21)
Cumming: 11 (18)
Conclusion
X-ray burst astronomy
is a thriving field
with a promise to extract
fundamental NS-data