1. Pulsar and Transient Science with the 12m Antenna
Julia Deneva
Arecibo Observatory, 11 May 2010

2. Antenna & Receiver Parameters
@ 2.4GHz
@ 8.4GHz
FWHM (arcmin) 43
12.3
Gain (K/Jy)
0.023
Tsys (K) 50 60
Ssys (Jy)
1816
2179
BW (MHz)
100
400
σ (Jy)
0.128 Tobs-1/2
0.077 Tobs-1/2
Gain assumes 65% aperture efficiency
Ssys = Tsys / G
Tsys and BW are anticipated values
σ = Ssys / (Npol*BW*Tobs)1/2
(Tobs->W for single pulses)
Av. spectral index for pulsars is -1.5, so 2.4GHz is better for pulsar observations.

3. Giant Pulse Monitoring
Giant pulses: 100 – 1000 times stronger than average pulse intensity.
Crab pulsar (P=0.033s)
Vela pulsar (P = 0.089s)
B (P = s)
The Crab pulsar emits on average
1 pulse/h with energy (integrated flux) of 104 Jy us
1 pulse/min with energy of 103 Jy us
5-sigma detection threshold for W=1us is 642 Jy

4. Giant Pulse Monitoring Applications
Detection of glitches and timing noise to probe internal structure of the neutron star.
Simultaneous observing with GLAST to facilitate folding of gamma-ray data and probe emission regions in pulsar magnetosphere
Statistical studies of giant pulses.
International time reference for telescopes participating in NanoGrav and similar projects
Aim to detect gravitational waves via observing correlated timing perturbations in fast pulsars spread over the sky.
GP are bright, and have substructure on the order of ns—ideal for “synchronizing clocks” across sites.

5. Normal Pulsar Monitoring
Vela
Crab B
Red line: 5-sigma detection threshold, Tobs = 1h

6. Transient Search
Wide beam of 12m antenna is ideal for all-sky transient surveys.
Nearby Rotating Radio Transients (RRATs)
Supernovae: single broadband radio pulse of <1s duration.
Gravitational wave sources: coalescing neutron stars may produce radio emission precursors to grav.wave signature of merger.
Coalescing primordial black holes

7. Rotating RAdio Transients (RRATs)
Very intermittent: a few pulses per hour on average.
11 found in 1.4GHz Parkes Multibeam survey (McLaughlin et al. 2006): 10 periods 0.4-7s
7 found in 1.4GHz PALFA survey at Arecibo (Deneva et al. 2009): 7 periods s
A new class of objects? Unusually small duty cycles; pulse intensity distribution is different from giant pulses of young pulsars.
If ~10000 detectable pulsars in the Galactic disk, 4-5 times more RRATs? Simulations of the RRAT population still remain to be done.
Insert plots from Maura’s RRAT paper J
P = 4.76s J
P = 0.77s

8. List of trial dispersion measures (DMs)
Delay times
Dedispersed time series for each trial DM
Trial DM at which pulse SNR peaks is closest to actual DM
Include a simple delta t ~ DM * <what constant> to get an idea of how much delays vary with DM at 9 GHz; Remove plot??
Can estimate distance from DM, sky coordinates, and model of ionized gas in Galaxy (Lazio & Cordes 2002)

9. Single Pulse Candidate Verification
Are single pulses dispersed?
Get pulse time of arrival from SP candidate list
Extract dynamic spectrum chunk around pulse and plot:
Can fit Δt ~ 1/f2 curve to dispersion sweep in dynamic spectrum for a more precise DM estimate J
DM = 96 pc/cc J
DM = 242 pc/cc

10. The “Lorimer Burst”
Found in Parkes data from survey of the Small Magellanic Cloud (Lorimer et al. 2006)
Dispersion sweep in dynamic spectrum fits the cold plasma dispersion relation perfectly.
Peak flux is ~30Jy, pulse width is 5ms.
Black horizontal line is due to a bad frequency channel.
Inset: pulse profile after dedispersion and summing all channels.

11. The “Lorimer Burst,” cont’d
Detected in 3 adjacent beams of the 13-beam Parkes receiver.
In projection near, but not in, the SMC.
DM = 375 pc/cc
Estimated DM contributions from Galactic ionized gas: 25 pc/cc
SMC distance: ~61kpc
Upper bound on distance to L. Burst progenitor: <1Gpc
Marked objects: pulsars in the SMC with their DMs.
J : higher DM b/c it’s in or behind a HII region.

12. The “Lorimer Burst”, alas…
Nothing seen again from same region despite ~90h of follow-up observations.
Not likely a RRAT or giant pulse—power-law pulse intensity distributions typical of these would mean that multiple weaker pulses should have been detected.
Likely a radio counterpart to SN, gamma-ray burst (though none were detected in this area by dedicated monitoring programs), NS merger, or BH merger.
BUT…
In later years, similar events from widely different sky positions. Eventually tracked down to RFI.

13. PALFA Single Pulse Discoveries
What portion of total AO sky is the GP?
Results only from searching the part of the Galactic plane visible to Arecibo.
All-sky search not practical with big dish because the FOV is tiny; but feasible with 12m antenna.

14. PSR J
P = 0.402s
DM = 242 pc/cc
Not detected again despite multiple follow-up observations

15. RRAT J
One-time detection of 3 pulses emitted on consecutive rotations; P = 0.402s.
Possible non-beacon explanation: dormant emission mechanism was momentarily revived by accretion of debris from a debris disk (Cordes & Shannon 2008).