Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userPeriodic mode changing in PSR J1048-5832
100
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
By analysing the data acquired from the Parkes 64-m radio telescope at 1369 MHz, we report on the phase-stationary non-drift amplitude modulation observed in PSR J1048-5832. The high-sensitivity observations revealed that the central and trailing components of the pulse profile of this pulsar switch between a strong mode and a weak mode periodically. However, the leading component remains unchanged. Polarization properties of the strong and weak modes are investigated. Considering the similarity to mode changing, we argue that the periodic amplitude modulation in PSR J1048$-$5832 is periodic mode changing. The fluctuation spectral analysis showed that the modulation period is very short (~2.1 s or 17 P1), where P1 is the rotation period of the pulsar. We find that this periodic amplitude modulation is hard to explain by existing models that account for the periodic phenomena in pulsars like subpulse drifting.
rate research
Read More
PSR J1048-5832 is a Vela-like (P=123.6 ms; tau~20.3 kyr) gamma-ray pulsar detected by Fermi, at a distance of ~2.7 kpc and with a rotational energy loss rate dot{E}_{SD} ~2 x 10^{36} erg/s. The PSR J1048-5832 field has been observed with the VLT in the V and R bands. We used these data to determine the colour of the object detected closest to the Chandra position (Star D) and confirm that it is not associated with the pulsar. For the estimated extinction along the line of sight, inferred from a re-analysis of the Chandra and XMM-Newton spectra, the fluxes of Star D (V~26.7; R~25.8) imply a -0.13 < (V-R)_0 < 0.6. This means that the PSR J1048-5832 spectrum would be unusually red compared to the Vela pulsar.Moreover, the ratio between the unabsorbed optical and X-ray flux of PSR J1048-5832 would be much higher than for other young pulsars. Thus, we conclude that Star D is not the PSR J1048-5832 counterpart. We compared the derived R and V-band upper limits (R>26.4; V>27.6) with the extrapolation of the X and gamma-ray spectra and constrained the pulsar spectrum at low-energies. In particular, the VLT upper limits suggest that the pulsar spectrum could be consistent with a single power-law, stretching from the gamma-rays to the optical.
PSR J1825$-$0935 (PSR B1822$-$09) switches between radio-quiet (Q-mode) and radio-bright (B-mode) modes. The Q-mode is known to have a periodic fluctuation that modulates both the interpulse and the main pulse with the same period. Earlier investigators argued that the periodic Q-mode modulation is associated with drifting subpulses. We report on single-pulse observations of PSR J1825$-$0935 that were made using the Parkes 64-m radio telescope with a central frequency of 1369 MHz. The high-sensitivity observations revealed that the periodic Q-mode modulation is in fact a periodic longitude-stationary intensity modulation occurring in the interpulse and the main pulse. The fluctuation spectral analysis showed that the modulation period is about $43 P_1$, where $P_1$ is the rotation period of the pulsar. Furthermore, we confirm that the modulation patterns in the interpulse and the main pulse are phase-locked. Specifically, the intensities of the interpulse and the immediately following main pulse are more highly correlated than for the main pulse and interpulse at any other lag. Polarization properties of the strong and weak Q-mode states are different, even for the trailing part of the main pulse which does not show the periodic intensity modulation.
We report a detailed observational study of the single pulses from the pulsar J1822$-$2256. The pulsar shows the presence of subpulse drifting, nulling as well as multiple emission modes. During these observations the pulsar existed primarily in two modes; mode A with prominent drift bands and mode B which was more disorderly without any clear subpulse drifting. A third mode C was also seen for a short duration with a different drifting periodicity compared to mode A. The nulls were present throughout the observations but were more frequent during the disorderly B mode. The nulling also exhibited periodicity with a clear peak in the fluctuation spectra. Before the transition from mode A to nulling the pulsar switched to a third drifting state with periodicity different from both mode A and C. The diversity seen in the single pulse behaviour of the pulsar J1822$-$2256 provides an unique window into the emission physics.
We report a detailed analysis of the emission behaviour of the five component, core-double cone, pulsar J2006$-$0807 (B2003$-$08). The single pulses revealed the presence of the three major phenomena of subpulse drifting, nulling and mode changing. The pulsar switched between four different emission modes, two of which showed systematic drifting with prominent drift bands, and were classified as modes A and B respectively. The drifting was seen primarily in the conal components and exhibited the rare phenomenon of bi-drifting, where the drift direction in the second component was opposite to the fourth component. This made PSR J2006$-$0807 the only known example where systematic drift bands were seen around a central core emission. The emission showed a gradual decrease in intensity during mode A which stabilised to a relatively constant level in the subsequent mode B. The presence of a low frequency, weak and wide structure in the fluctuation spectra was also seen primarily in the core component during modes A and B. The core component vanished during mode C and was most prominent during the fourth mode D. Both these modes were frequently interspersed with null pulses. No detectable drifting was seen during modes C and D, but the pulsar showed short duration periodic nulling in the core as well as the conal components. In addition to the four emission modes the pulsar also nulled for long durations lasting up to hundred rotation periods.
In this study, we report on a detailed single pulse polarimetric analysis of the radio emission from the pulsar J2321+6024 (B2319+60) observed with the Giant Metrewave Radio Telescope, over wide frequencies ranging between 300 to 500 MHz and widely separated observing sessions. The pulsar profile shows the presence of four distinct conal components and belongs to a small group of pulsars classified as a conal quadrupole profile type. The single pulse sequence reveals the presence of three distinct emission modes, A, B, and ABN showing subpulse drifting. Besides, there were sequences when the pulsar did not show any drifting behaviour suggesting the possibility of a new emission state, which we have termed as mode C. The evolution of the mode changing behavior was seen during the different observing sessions with different abundance as well as the average duration of the modes seen on each date. The drifting periodicities were 7.8$pm$0.3 $P$, 4.3$pm$0.4 $P$, and 3.1$pm$0.2 $P$ in the modes A, B and ABN respectively, and showed large phase variations within the mode profile. The pulsar also showed the presence of orthogonal polarization modes, particularly in the leading and trailing components, which has different characteristics for the stronger and weaker pulses. However, no correlation was found between the emission modes and their polarization behavior, with the estimated emission heights remaining roughly constant throughout. We have used the Partially Screened Gap model to understand the connection between drifting, mode changing, and nulling.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
