The “Holey” Grail of Pulsars

By: Jurni Fink, Alexx Lee, and Annie NealonBy: Jurni Fink, Alexx Lee, and Annie Nealon

(Broadway High School, Broadway, VA )(Broadway High School, Broadway, VA )

The Binary Question…The Binary Question…

Imagine a radically, nigh-impossible Imagine a radically, nigh-impossible idea: the co-existence of a pulsar idea: the co-existence of a pulsar and a black hole in a binary system. and a black hole in a binary system. This poster seeks to explain how This poster seeks to explain how that binary system would be that binary system would be possible and by using the analysis of possible and by using the analysis of a medley of pointings and deductive a medley of pointings and deductive reasoning, attempts to predict how a reasoning, attempts to predict how a theoretical binary system would theoretical binary system would appear, as observed by a radio appear, as observed by a radio telescope. telescope.

How the System WorksHow the System WorksA Kerr vacuum is so massive that as A Kerr vacuum is so massive that as it rotates it warps and makes waves it rotates it warps and makes waves in the fabric of space-time. A pulsar in the fabric of space-time. A pulsar could stay in orbit using these could stay in orbit using these waves, which are located in the waves, which are located in the ergosphere, an elliptical area ergosphere, an elliptical area surrounding the event horizon.surrounding the event horizon.

There are a few ways to detect such There are a few ways to detect such a system. First of all, the timing of a system. First of all, the timing of the pulses would speed up as the the pulses would speed up as the pulsar gains momentum and would pulsar gains momentum and would therefore “feed” the pulsar. The therefore “feed” the pulsar. The period would also speed up as the period would also speed up as the pulsar moves closer to the event pulsar moves closer to the event horizon drawn from the singularity. horizon drawn from the singularity. Another way to detect this is a Another way to detect this is a normally timed eclipse of the pulsar; normally timed eclipse of the pulsar; as it orbits the black hole, the black as it orbits the black hole, the black hole would periodically cover up its hole would periodically cover up its signal. signal.

Relation to Singular PulsarsRelation to Singular Pulsars

Basically, if an observer were to find Basically, if an observer were to find this theoretical binary system, this theoretical binary system, initially it would appear as an initially it would appear as an ordinary pulsar. In an ideal ordinary pulsar. In an ideal observation the profile plot would observation the profile plot would look much like as in Figure 1, as look much like as in Figure 1, as would the time-phase, sub-band-would the time-phase, sub-band-phase and reduced χphase and reduced χ22-DM plots -DM plots (taking into account however that (taking into account however that DM-χDM-χ2 2 and strength of signal will and strength of signal will vary). However, two exceptions are vary). However, two exceptions are required to be taken into account. required to be taken into account. First, the period of the pulsar would First, the period of the pulsar would not only change, but also have a not only change, but also have a spin-up rate rather than a spin-down spin-up rate rather than a spin-down rate, due to the gained momentum rate, due to the gained momentum as the pulsar approaches the as the pulsar approaches the singularity. Second, the DM would singularity. Second, the DM would have to be adjusted slightly due to have to be adjusted slightly due to the warped signal from the the warped signal from the gravitational waves. However, the gravitational waves. However, the initial observation of a binary pulsar-initial observation of a binary pulsar-black hole system would appear black hole system would appear much like that of a singular pulsar much like that of a singular pulsar (Figure 2). (Figure 2).

Defined AssumptionsDefined AssumptionsThere are four different types of There are four different types of black holes, or exact solutions to the black holes, or exact solutions to the Einstein field equation of general Einstein field equation of general relativity. The most ideal candidate relativity. The most ideal candidate for a binary system with a pulsar is a for a binary system with a pulsar is a Kerr metric or Kerr vacuum. A Kerr Kerr metric or Kerr vacuum. A Kerr black hole is an uncharged rotating black hole is an uncharged rotating black hole, proposed in 1963 by Roy black hole, proposed in 1963 by Roy Kerr. Because the mass and Kerr. Because the mass and gravitational pull of a black hole is gravitational pull of a black hole is much greater than that of its much greater than that of its conceivable companion, the conceivable companion, the improbable pulsar would at some improbable pulsar would at some point it its existence be a millisecond point it its existence be a millisecond pulsar. Even if it did not start as a pulsar. Even if it did not start as a millisecond pulsar, it would slowly millisecond pulsar, it would slowly speed up as the black hole draws it speed up as the black hole draws it nearer to its singularity.nearer to its singularity.

ConclusionConclusionUltimately, if such a binary system Ultimately, if such a binary system were to exist betwixt a black hole were to exist betwixt a black hole and a pulsar, its signal would not and a pulsar, its signal would not differ initially from that of a single differ initially from that of a single pulsar. However, further observation pulsar. However, further observation would illuminate the prospective would illuminate the prospective binary system and revolutionize binary system and revolutionize astrophysics due to supporting or astrophysics due to supporting or refuting Einstein’s Theory of General refuting Einstein’s Theory of General Relativity.Relativity.

AcknowledgementsWe thank the sky, the stars, and Mufasa above For teaching us things or locking us up

The Scientists, the geniuses, and the men in white coats Till we go mad looking for pulsars in all our lost luckMcLaughlin, Maura, and Francis Graham-Smith. "A Magnetopause in the Double-pulsar Binary System." A&G, Feb. 2005. Web. 20 May 2013

Wikipedia.

Rushton, A., and R. Ferdman. "BLACK HOLES IN A VIOLENT UNIVERSE." BLACK HOLES IN A VIOLENT UNIVERSE.

"Inside a Black Hole." Inside a Black Hole. Nrumiano).

Figure 1; an FFT plot of J1910-259. A black hole-pulsar binary system plot would be very

similar to this FFT plot.

Figure 2; a single pulse plot of J1910-259.

A. Rushton et al; A black hole’s gravitaional force bends space-time, warping the orbit of the pulsar that follows the gravitational waves it creates.

The strength of the black hole ebbs as it strays from the singularity outwards toward the ergosphere, where the theoretical pulsar would exist.