Single pulses from the pulsars B0809+74 and B1133+16 with LOFAR LBAs

Vlad Kondratiev
LOFAR Transients Key Project Meeting, Meudon, December 2011

Transcript

1. Single pulses from the pulsars B0809+74 and B1133+16 with LOFAR LBAs Dec 15, 2011 LOFAR TKP Meeting, Meudon, France Vlad Kondratiev (ASTRON) and LOFAR Pulsar Working Group
2. LOFAR Pulsar Working Group Ben Stappers Jason Hessels Anastasia Alexov Joeri van Leeuwen Tom Hassal Aris Karastergiou Aris Noutsos Charlotte Sobey Joris Verbiest Michael Kramer Patrick Weltevrede Kimon Zagkouris Thijs Coenen Evan Keane Ashish Asgekar Jan David Mol John Romein and many others …. Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
3. Regular Giant Dec 15, 2011 LOFAR TKP Meeting, Meudon, France Drifting subpulses, nulling Single­pulse phenomena (B0809+74, van Leeuwen et al., 2002) Spiky emission (B0656+14, Weltevrede et al., 2006) Giant (B1937+21, Soglasnov et al., 2004) Giant pulse & micropulses (Rankin et al., 2006)
4. Regular Giant Dec 15, 2011 LOFAR TKP Meeting, Meudon, France Drifting subpulses, nulling Single­pulse phenomena (B0809+74, van Leeuwen et al., 2002) Spiky emission (B0656+14, Weltevrede et al., 2006) Giant (B1937+21, Soglasnov et al., 2004) Giant pulse & micropulses (Rankin et al., 2006) Most of the studies and observed phenomena @ >1 GHz
5. → @ lower frequencies, 40­111 MHz (series of Kuzmin, and Ershov & Kuzmin papers) B1112+50 B0031-07 + B0656+17 J1752+2359 Giants? Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
6. → @ lower frequencies, 110­180 MHz (Karuppusamy et al., 2011) Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
7. Dec 15, 2011 LOFAR TKP Meeting, Meudon, France B0809+74 Ul'yanov et al. (2006) UTR-2 @ 18-30 MHz Termed «Anomalously Intensive Pulses» (AIPs) by Ul'yanov et al. B0809+74, B0950+08, B1133+16, B0823+26, B0834+06, B0943+10 S peak > 20 S peak of average profile Occur in groups Very rare, only 5­10% of observing time Very narrow spectra, 1.5­5 MHz wide; sometimes in 2­3 emission bands @ low freqs < 30 MHz
8. Dec 15, 2011 LOFAR TKP Meeting, Meudon, France B0809+74 Ul'yanov et al. (2006) UTR-2 @ 18-30 MHz Termed «Anomalously Intensive Pulses» (AIPs) by Ul'yanov et al. B0809+74, B0950+08, B1133+16, B0823+26, B0834+06, B0943+10 S peak > 20 S peak of average profile Occur in groups Very rare, only 5­10% of observing time Very narrow spectra, 1.5­5 MHz wide; sometimes in 2­3 emission bands @ low freqs < 30 MHz • link to other single­pulse phenomena (giant pulses, micropulses, spiky emission) ? • Insight into pulsar emission mechanism
9. Dec 15, 2011 LOFAR TKP Meeting, Meudon, France ` LBA Superterp 15­65 MHz 2 hour/obs 244 subbands 32 chan/subband Coherent sum of the stations Stokes I t = 1.3 ms Δ LBA observations
10. Dec 15, 2011 LOFAR TKP Meeting, Meudon, France B0809+74 Bright narrow­band pulses
11. B1133+16 Bright narrow­band pulses Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
12. Dec 15, 2011 LOFAR TKP Meeting, Meudon, France B0809+74 72-78 MHz 66-72 MHz 60-66 MHz 54-60 MHz 48-54 MHz 42-48 MHz 36-42 MHz 30-36 MHz 28-34 MHz 22-28 MHz 16-22 MHz 10-16 MHz Average profile 63 MHz 15 MHz
13. Dec 15, 2011 LOFAR TKP Meeting, Meudon, France B1133+16 Average profile 63 MHz 15 MHz B0809+74
14. 2­D search Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
15. B0809+74 S/N>35 S/N>20 B1133+16 S/N>20 S/N>20 Profiles (Kondratiev et al., in prep) Preliminary Each profile normalized by its maximum Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
16. Spectra B0809+74 Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
17. Spectra B0809+74 Preliminary Stronger pulses tend to come in the inner edge of the components Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
18. Spectra B1133+16 Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
19. Spectra B1133+16 Preliminary Stronger pulses tend to come in the inner edge of the components Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
20. B0809+74 Preliminary Only for pulses >10σ Separate group of strong pulses? Dec 15, 2011 LOFAR TKP Meeting, Meudon, France Pulse energy distribution Normalized by mean energy
21. Preliminary Only for pulses >10σ Pulse energy distribution B0809+74 Separate group of strong pulses? Dec 15, 2011 LOFAR TKP Meeting, Meudon, France Normalized by mean energy
22. Pulse energy distribution B1133+16 Preliminary Only for pulses >10σ Normalized by mean energy Dec 15, 2011 LOFAR TKP Meeting, Meudon, France ?
23. Pulse energy distribution B1133+16 Preliminary Only for pulses >10σ Normalized by mean energy Dec 15, 2011 LOFAR TKP Meeting, Meudon, France ?
24. B0809+74 2­D histograms of f vs. f ∆ B1133+16 Preliminary (Kondratiev et al., in prep) Pulses are narrow in frequency in general Preliminary Pulses are broad in frequency ∆f/f ~ 0.1 (strong plasma turbulence?) Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
25. Pulse width vs. Phase B1133+16 B0809+74 Preliminary (Kondratiev et al., in prep) Preliminary Pulses in general are narrower than average profile, tend to be wider for the second component Pulses not much narrower than average profile and they occur more often in the second component Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
26. ISM scintillations ? ISM scintillations are averaged out ∆ν d < 100 Hz @20 MHz ∆ν d ~ 7 kHz @ 50 MHz chan BW ≈ 100 kHz B0809+74 LBA dynamic spectrum Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
27. ISM scintillations are averaged out ∆ν d < 100 Hz @20 MHz ∆ν d ~ 7 kHz @ 50 MHz chan BW ≈ 100 kHz B0809+74 LBA dynamic spectrum HBA dynamic spectrum ISM scintillations ? Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
28. Ionosphere ? → The rate of change of ionosphere state is long (dozens of mins), but the strong pulses can occur in a succession of periods → Strong pulses tend to occur at the preferential phase — inner edge of the components. If due to ionosphere, their occurence would be random in phase Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
29. Ionosphere ? Must be intrinsic to the pulsar → The rate of change of ionosphere state is long (dozens of mins), but the strong pulses can occur in a succession of periods → Strong pulses tend to occur at the preferential phase — inner edge of the components. If due to ionosphere, their occurence would be random in phase Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
30. Summary Bright, low­frequency, narrow­band pulses from pulsars B0809+74 and B1133+16 are consistently observed with LBAs. The origin of these pulses is pulsar­intrinsic rather than due to propagation effects in ISM or ionosphere. Strong pulses tend to occur at the inner edge of both components, and for the pulsar B0809+74 are usually both narrow in frequency and time. For the B1133+16 pulses in general are broad in frequency. For the pulsar B0809+74 spectral width of pulses in general increases with the increasing frequency and qualitatively agrees with f/f ~ 0.1 expected for strong ∆ plasma turbulence models. Strong energetic pulses with E > 10<E> (conventional definition of GPs) for both pulsars B0809+74 and B1133+16 resemble those observed from B1133+16 at 110­180 MHz and may indicate the link of the emission to the spiky emission or giant pulses. Dec 15, 2011 LOFAR TKP Meeting, Meudon, France
31. Future work Instantaneous 10­250 MHz observations (almost there!) More regular observations of pulsars that show strong pulses at low frequencies Using online coherent dedispersion for higher time­resolution studies Polarization data Dec 15, 2011 LOFAR TKP Meeting, Meudon, France