finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
finding pulsars with lofar
joeri van leeuwen (uc berkeley)
ben stappers (astron)
http://astro.berkeley.edu/~joeri/
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
telescope evolution
flat, single beam nearby bright slow pulsars
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalactic globular clustersextragalacticconclusions
telescope evolution
dish, multiple beams fast / binary pulsars
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
telescope evolution
lofar: many simple receivers + supercomputer all nearby pulsars
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
simulation
life, evolution and death of 107 neutron stars detection by all previous pulsar searches detection for different lofar configurations
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
simulation
Survey Simulated Detected MolongloII 230 224 UMass-NRAO 60 50 ParkesMB 800 980 Cambridge 80MHz 93-94 25 20 SKA 15-20k
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
simulation
lofar compact core setup 2km wide, 32 x ~60-meter stations each containing 96 high-frequency antennae effective area towards zenith of >25m2 / antenna combined in/coherently to 8 (later 24) beams
0 30 60 90Zenith angle (degrees)
Effe
ctiv
e ar
ea p
er ti
le (m
2 )
10
0
20
30
Com
pact
cor
e ga
in (K
/Jy)
10
0
20
30120MHz
160MHz
240MHz
200MHz
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
galactic pulsar searches
coherent addition beamsize = 0.0044 deg2 incoherent addition beamsize = 1.8 deg2
in 'sparse' telescopes, incoherent addition is usually better for all-sky surveys
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
galactic pulsar searches
fast, sensitive pulsar surveys possiblydoubling the known pulsar population
0 32168 64 128Pointings (minutes)
60 days with 8 beams
Num
ber o
f det
ecte
d pu
lsar
s
0
2500
2000
1500
1000
500
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
galactic pulsar searches
optimum frequency (pulsar brightness, background, scattering) determined by dipoles
120 160 200 240Observing frequency (MHz)
Num
ber o
f det
ecte
d pu
lsar
s
0
2500
2000
1500
1000
500
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
at 140 MHz radio-wave scattering is limiting;lofar detects the full local population
Lofar detectionParkesMB detectionGalactic centerSun
-20
-10
-20
y p
osi
tio
n (
kpc)
010
20
-10 0x position (kpc)
10 20
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
at 140 MHz radio-wave scattering is limiting;lofar detects the full local population
Lofar detectionParkesMB detectionGalactic centerSun
-20
-10
-20hei
gh
t ab
ove
th
e g
alac
tic
pla
ne
(kp
c)0
1020
-10 0x position (kpc)
10 20
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
neutron star birth velocities from z-distribution supernova kicks, binary disruption
Lofar detectionParkesMB detectionGalactic centerSun
-20
-10
-20hei
gh
t ab
ove
th
e g
alac
tic
pla
ne
(kp
c)0
1020
-10 0x position (kpc)
10 20
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
finds all pulsars within 1kpc the first count of the weak, previously invisible pulsars near the sun reliable birthrates which stars form pulsars
can find sub-millisecond pulsars within 1kpc if they exist
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
globular cluster pulsar searches
high stellar densities and interaction rate many interesting binaries limited regions on the sky: coherent addition
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
doubles the number in M15 with a single beam
finding pulsars with lofarvan leeuwen
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
extragalactic searches
for normal periodicities or for 'giant pulses' detect the 10 brightest pulsars in M33 detect Crab-like giant pulses from M81
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
finding pulsars with lofarvan leeuwen
introtelescopessimulationgalacticglobular clustersextragalacticconclusions
conclusions
lofar can double the known pulsar population finds all local pulsars probes nearby globular clusters very deeply can find extragalactic pulsars
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