Montoring of Giant Pulses with the LPA LPI at the frequensy of 111 MHz

Transcription

1 YERAC-2013 Montoring of Giant Pulses with the LPA LPI at the frequensy of 111 MHz Kazantsev A.N.(1,2) & Potapov V.A.(1) (1) PRAO ASC LPI, Pushchino (2) Pushchino State Nat.Sci.Inst., Pushchino Bielefeld, 2013

2 Giant Radio Pulses (GRPs) of pulsars. Strong individual pulses tens, hundreds, thousands time as strong as averaged pulse. Peak flux density about hundreds, thousands and even millions Jy (when typical pulsar averaged pulse s flux is several Jy). High level of linear and circular polarization of pulse. E.g. ~60% GRP of PSR B are 100% circular polarized. GRPs have a power law distribution both for peak flux and pulse s energy. Normal pulses have a Gaussian distribution on a logarithmic scale. GRPs have duration of several nanoseconds, e.g. B (Soglasnov et al, 2004) GPs microstructure component may be as short as nanosecond or less, e.g. B (Hankins et al., 2003). The highest brightness temperature: B TB K; B TB K

3 «Classical» GRPs Pulsar in Crab nebulae (B ) has most famous and the first discovered GRPs. The shortest ever observed component of GRP of the Crab pulsar (Hankins et al, 2003) S 5 MJy Kalyazin (Russia), 2005, 2244 MHz, B = 16 MHz (Popov et al. 2005)

4 GRPs energy distribution, B Popov et al., 2009

5 Individual pulses energy distribution, B Cognard et al. 1996

6 Histograms of relative peak flux (vs. flux of averaged profile), classification MHz (Hesse & Wielebinski), 1974

7 Pulsars with GRPs Name P, s P1, s/s Frequenc y, MHz DM, sm-3 pc B on LC, Gs First reference J e e J e e J e e J * e e J * e e J e e J e e J e e B ** e e J e e J e e J e e J e e J e e * - pulsar in LMC, ** - discovered in our observations

8 Open questions. What are the differences in properties/statistics for pulsars from 3 sets mentioned above? How many pulsars with low BLC have GRPs? How strict and valuable statistical criterion is? (Power law/gaussian distribution of pick flux for GP/normal pulses)? How stable are GRPs generated and how their properties change at long time intervals? Have to collect long data set to test different theories of GRPs generation. The same or two different models for normal and GRPs generation?

9 Goals and program of research. To make regular long time observations of pulsar. Observations of strong second and millisecond pulsars at 111 MHz frequency. Search for pulses with peak flux in more than 30 average pulse. Building distributions on peak flux/energy for these pulses. Testing of statistical criterion by comparison distributions for pulsars with GRPs and regular pulsars,

10 LPA of LPI radio telescope Scanning meridional phased array, One linear polarization. Frequency: 111 MHz, Bandwidth: 2.3 MHz (460 x 5 khz digital receiver with post-detector DM removal); Duration of one scan: 3 to 7 min. (e.g. B min = 153 pulses);

11 Objects observed 36 pulsars: J J J J J J J J J J J J J J J J J J J J J J J J B J J J J J J J J J J J

12 Negative results No regular GRPs for: J (B ), J (B ) & J (40, DCR-100 & MHz, LPA LPI) J & J (B ) (610 MHz, GMRT). Strongest detected pulse of B

13 Positive results First discovered GRPs of B (J ) Regular GRPs confirmed for B & B Strong individual pulses of B were found (S > 20 ave. pulse) observed earlier in decameter wavelengths (Ulyanov et al. 2006)

14 GRPs of B ( & )

15 Individual pulses histograms. 111 MHz 2695 MHz Differs for histogram at 2695 MHz (no sub=peaks). Much stronger in maximum K.H. Hesse & R. Wielebinski, 1974

16 GRP peak flux distribution (B ) ± ±0.34 Strongest GRP: Smax = 900±200 Jy.

17 GRPs B monitoring GRPs of B distributions Ershov, Kuzmin, 2003 Kazantsev, Potapov, 2013

18 GRPs B monitoring 111 MHz 2695 MHz

19 GRP phase distribution (B ), mode changes.

20 GRP peak flux distribution (B ) ± ±0.07 Results are consistent with early obtained (Smirnova, 2012)

21 Search for GRPs of PSR B Individual pulses peak flux distribution ±0.50

22 Individual pulses of B MHz 2695 MHz

23 Individual pulses peak flux distribution (B ) -1.01± ±0.48

24 Statistics of monitoring Pulsar name Flux in averaged profiles >5 >10 >15 >20 >30 >50 >100 B B B B B

25 Summary For the first time discovered GRPs of PSR B , and, probably of PSR B (early detected as strong wide pulses at 23.7MHz). It can be separated subset of pulsars with GRPs, having BLC ~ 1100 Gs, quite wide profiles and tenths or hundreds times stronger than averaged pulses. Such GRPs may be observed at meter and decameter wavelengths (referred as Anomalous Intensive Pulses - AIP). This subset of pulsars with GRPs maybe wide distributed between second period pulsars. We d found 3.3 (6.6?) % of such pulsars in our random sampling of objects. Statistical criterion is not quite valuable because of regular pulsars (I/II type in Hesse-Wielebinski classification) may have the similar power law distribution of strong pulses. Some of such pulsars have nullings in GRP generation (3 from 7 pulsars in our sample).

26 Vielen Dank für Ihre Aufmerksamkeit Спасибо за внимание Thank you for your attention