RRAT J1541+4703: A Rotating Radio Transient Exhibiting Normal Pulsar States

Abstract

Rotating Radio Transients (RRATs) are a class of pulsar-like objects characterized by intermittent radio emissions. Among them, RRATs that exhibit both RRAT and normal pulsar (NP) states may represent a key evolutionary stage from nulling pulsars to RRATs. We performed a detailed analysis of RRAT J1574+4703 using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) at a frequency of 1250 MHz. Our findings indicate that this RRAT spends approximately 98% of its time in the RRAT state, with the remainder spent in an NP state exhibiting nulling behavior. Additionally, we observed distinct integral pulse profiles and polarization properties between the two states, suggesting that they originate from different emission heights and magnetospheric structures. Furthermore, it was observed that the NP states of this RRAT exhibit mode switching, with ~44% of the time spent in the normal mode and ~39% in the abnormal mode. Notably, abnormal modes are predominantly detected at the onset and termination of the NP states. This discrepancy between the modes indicates potential instability in the magnetospheric processes that govern the NP states.

Figures (11)

• Figure 1: Number of burst pulses detected under different threshold combinations.
• Figure 2: The polarized integrated pulse profile of RRAT J1541+4703 from seven epochs, including all burst pulses, NP states, and RRAT states. In the top panel of each row, red and gray dots denote the PA of the integrated pulse profile and that of a single pulse, respectively. The solid and dashed black lines indicating RVM fitting curves separated by $90^{\circ}$. The corresponding bottom panel shows total intensity (black line), linear polarization (red line), and circular polarization (blue line). All pulse profiles have been normalized to peak intensity.
• Figure 3: Results of the three Gaussian fits for the integrated pulse profile. The black solid line represents the integrated pulse profile, the red solid line the fitted curve, and the blue dashed line the single Gaussian component. The residuals of the fit are represented by the yellow curves.
• Figure 4: An example of the posterior distributions for four parameters in RVM model fitting. The contours represent $1 \sigma$, $2 \sigma$, and $3 \sigma$ confidence levels. The vertical dashed lines in the top panel of each column indicate the 16th, median, and 84th percentiles of the distribution. The fitted values and their errors for each parameter are labeled at the top of the figure in degrees.
• Figure 5: Single pulse stack of 500 consecutive pulses from RRAT J1541+4703, exhibiting both RRAT and pulsar emission states. The right panel shows the fluence for each pulse, with distinct null pulses observed in both states.