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Detection of Novae & Black Holes
QND-type gravity detectors which "ring" around 500-600 Hz at the input are ideal for detecting the actual formation of the neutron star or black hole in the super-nova-type astronomical event. These will appear as gaussian-type pulses when displayed on an oscilloscope. However, nova and supernova, as well as the resulting black hole type structures which appear following the supernova events, are best displayed with the l/f type "shadow" gravity detectors, where the output is integrated to obtain an envelope-type response for the event. Simple explanations for these types of responses follow:
Novae are stars which "explode" and thus eject some of their outer layers and most of their atmosphere. This is a momentary and transitory type of event which must be "caught in the act", so to speak, since they do not ordinarily leave permanent traces which may be "observable" with this system in further scans of that region. The novae generally have two characteristic "signatures" when detected with shadow-type detection systems. These are depicted in Figure (1). As the extremely fine resolution "beam" of the detector scans a nova event (as a function of the rotation of the earth), it will first detect the actual explosion, primarily as a sharp gradient in the earth's gravity field, due to the "modulation" of the earth gravity field by the sudden displacement of a large amount of mass at the nova event. As the "beam" moves with the earth rotation, it will pull away from that expanding mass in the nova event and thus the response will fall off, or tail, as shown in the depiction of Figure (1). In some cases, some shock-wave modulations may appear, if the exploding star was in or near a gassy or dusty environment. Nova events apparently occur quite often and thus are also "seen" quite often with this detection system.
Figure 1: Nova Event Response
Figure 2: Supernova Event Response
Supernovae are believed to be the demise of some more massive stars and thus are less frequent events than supernovae, but still are "seen" fairly often with the shadow detection systems. This is primarily due to the fact that supernovae are detectable when located anywhere on the detector’s meridian location, but generally in the zenith regions or directly through the earth. However, the detections can be limited to certain depths in space by properly adjusting the output signal integration, i.e., the output filter of the detection circuitry.
Supernovae responses as detected with this system generally have three characteristic signatures as is depicted in Figure (2). Initially "seen" is the collapse of the star to a neutron star or black hole. While this is noted as a gaussian-type "ring" in the QND type of detectors, in the shadow type detectors it appears as a very sudden change in averaged earth gravity levels, due both to the movement of much mass in the supernova event as well as its compaction (implosion) into the neutron star or black hole. This is followed immediately by the explosive burst of much of the star's outer layers and atmosphere. Since much mass is involved in this process (with high velocity movements), the shock-wave front from the core event will "pile up" some surrounding material as a ring (or rings) of debris which are also generally detectable with these systems. Again, due to the rotation of the earth, a "tailing" effect is also present. An additional characteristic response for supernovae is that they do generally leave some lasting traces of their existence, primarily the black holes and an "accretion" ring.
Black Hole Responses
A new black hole usually retains an accretion ring structure and the characteristic "signatures" are as depicted in Figure (3). They can be quite pronounced in the first few days following the supernova event. Here, the fine resolution scanning "beam" of the detector can sweep across the entire structure of the black hole and accretion ring as shown in Figure (3). The black holes and accretion rings have very long lifetimes, but the detection system may also pick up black holes without the accretion ring. These may be very old supernovae events which have since "lost" such structures in an in-fall type of mechanism. Our own galaxy Center now has a new and very pronounced "black hole" structure since about December 6, 1986!
Figure 3: Black Hole with Accretion Ring
These simple explanations of some prominent "observable" events in gravitational astronomy should be of interest to the inquisitive experimenter, as well as amateur astronomers. It should also be of prime interest to the professional astrophysicists once they are able to shed their "inhibitions" due to their academic training.