Download Radio Pulsars app to simulate pulsar observations on your phone.
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The Radio Pulsar app is now only available on the Apple platform.
Sorry for Android users; I'll work harder and try to bring the app to you.
In this version of the Radio Pulsars app, 'pulsar glitch' is added. 'Pulsar glitch', or 'glitch', is a phenomenon first observed in the Vela pulsar in 1969, about two years after the detection of the first pulsar. A glitch appears as an unexpected little negative step change in pulsar pulse period. As pulsar pulse frequency is period's inverse, a glitch is also an unexpected little positive change in pulse frequency. After more than half a century since the first discovery, we now have recorded 670 glitches (see Jodrell Bank Glitch Catalogue). When making counts to all the amplitudes of the glitch-induced step changes, we find glitches appear to have two groups. Some glitches are relatively large, they increase pulse frequencies by one part in a million. Some glitches are small, they only increase frequencies by one part in a billion. Pulsars have steady slowdowns, or their pulse frequencies drop with constant rates. Observations show glitches also cause step changes in the slowdown rates, normally negative. Thus, after glitches, pulsar slowdowns faster. Observations have further shown that, sometimes after the occurrences of glitches, pulsars have relaxation processes, usually in an exponential manner. The relaxation processes, or exponential decays, partially recover both pulse frequency and slowdown rate to what they were before a glitch.
Radio Pulsars app's first goal is to clearly manifest basic concepts in the studies on pulsars. For glitches, their first observable is the step change in pulse period. Therefore, Radio Pulsars app doesn't show pulsar slowdown. One can take this as we remove slowdowns to study period residuals, as what astronomers always do. Also, Radio Pulsars app doesn't show exponential decays (at least in this version; perhaps it will change its mind one day). The scale of period residuals in the app is adopted as the inverse of pulsar characteristic age (period over period time derivative, i.e. slowdown rate) in seconds. This is rather rough. Although obseravations show the younger the pulsar, the 'noisier' they are, the 'noisy' here refers to the scale of pulse phase residuals with year-long timescales. Despite this, Radio Pulsars app still takes such a way to give estimates to period residuals' scales within the a few minutes users play for.
Statistical studies show, for an individual pulsar, intervals between glitches follow exponential distributions. Radio Pulsars app adopts this, i.e. interval = −1.0/average glitch rate × ln(1.0 − u). In principle, u is an uniform deviate between 0.0 (inclusive) and 1.0 (exclusive). In practice, Radio Pulsars app changes the lower bound to 0.3 to give a minimum interval 71 seconds. The average glitch rate, i.e. the pulsar's entire glitch number over its entire observing span, is from real observation records (one is the Jodrell Bank Glitch Catalogue, the other is the ATNF Pulsar Catalogue Glitch Database). A published value for the observing span by Espinoza C. M. et al. (2011) or Yu et al. (2013) is preferred. If such a value is not published, the observing span is adopted as the difference between the last glitch epoch and the first glitch epoch. The observing span is in fact in days; this makes the resulting glitch intervals in days or even longer. This is not practical. So Radio Pulsars app takes the observing span as in seconds; this is equivalent to say the average glitch rate is enlarged by a factor of 86,400. Despite this, the longest minimum glitch interval is still 4,693 seconds (78 minutes). Users can thus have a taste that celestial bodies' evolution is long term.
For glitch sizes (i.e. amplitudes of step changes), Radio Pulsars app draws a value from an uniform distribution with bounds being the minimum glitch and the maximum glitch seen in a pulsar, rather than from a power-law distribution revealed by statistical studies. This is because the power-law exponents are available for only a few pulsars.
In this version, there are 85 pulsars in the sample, with 26 glitching ones. The glitching pulsars are PSRs J0534+2200, J0601−0527, J0613−0200, J0726−2612, J0835−4510, J0940−5428, J1141−3322, J1248−6344, J1341−6220, J1531−5610, J1705−1906, J1705−3423, J1718−3825, J1740+1000, J1746−2856, J1801−2304, J1809−0119, J1812−1718, J1915+1606, J1957+2831, J2021+3651, J2022+5154, J2116+1414, J2219+4754, J2225+6535, J2346−0609.