ELOG Updates and Results

Updates and Results Talks and Posters Advice Ideas Important Figures Write-Ups Outreach How-To Funding Opportunities GENETIS

Important Plots, Tables, and Measurements

Fields marked with * are required
Entry time:	Tue Feb 3 10:56:23 2026
Author*:
Type*:
Category*:
Subject:
Project:
<p>See the attached papers.  I wonder if we could look for these with ANITA and distinguish between natural and artificial origin.</p> <p>Here are some estimates that I did last night.</p> <p>The paper quotes that for an FRB at a distance ~10-20 kpc, we would see at S_nu=10^10-10^11 Jy where 1 Jy=10^-26 W/m^2/Hz.</p> <p>For a BW=1 GHz and taking 1 m^2 effective area antennas, we get 10^-7-10^-6=V^2/R where R=50 Ohms, then taking the lower end of the range of S_nu gives V=2.2E-3 V.</p> <p>For anita V(thermal noise) is roughly V_rms=sqrt(k_BTBWR)=sqrt(1.38E-23 ~340 K * 10^9 Hz * 50 Ohms) = 1.5E-5 V.</p> <p>So let's say roughly we can hope to see signals down to the thermal noise level.  Then as expected, an FRB in our own galaxy should be easily observable.</p> <p>The paper estimates that in a galaxy there are ~10^-5 FRBs/day.  Wikipedia tells me that within 3.59 Mpc there are 127 known galaxies.  Given the observed voltage would go like 1/r, then the furthest ones from that group of 127 would be seen at voltages a factor of ~4 Mpc/20 kpc=200 lower, so the furthest ones would be right at the thermal noise level.</p> <p>When ANITA is at altitude, we perform our searches below the horizontal, and can hope to see radio signals directly from horizontal down to the horizon at about -6 deg.  So we view a sort of disk from 0 to 6 deg. in all directions in azimuth in payload coordinates.  This intersects the galactic plane at some angle but we can not just look for FRBs in our own galaxy but also in the other galaxies which we pretend to be uniformly distributed in a spherical volume.  If we could view from +90 deg. to -90 deg. then we would be able to see in all directions, so the fraction of the galaxy we can see is about 6/180=1/30.  So the probability that over roughly 100 total days of livetime over all flights, ANITA sees an FRB can be estimated as:</p> <p>Prob(seeing a FRB from within 3.59 Mpc)=10^-5 FRBs/day * 100 days * 127 galaxies * 1/30 = 0.004.</p> <p>If the intensity received is on the upper end of the range given (S_nu=10^11 Jy), then maybe we can see out to 40 Mpc.  Assuming the same density of galaxies as within 4 Mpc, since we're looking in a disk the # of galaxies goes like r^2, so we get a factor of 100 increase in prob-> prob=0.4, not bad.</p> <p><strong>But</strong>, we haven't accounted for the beam of the FRBs.  It appears at first glance in their paper that power increases at lower frequencies, and the beam width increases at lower frequencies, I'm not sure, and those two things would both be good for us since FRBs have been observed above a GHz and so we could see them at lower frequencies.</p> <p>Some things to look into:</p> <p>Understanding their calculations of the beam width and power, and the frequency dependence</p> <p>03/20:  It seems the beamwidth is based on some multiple of the diffraction limit lambda/D where D is the size of the source.</p> <p>How they are proposing one would be able to distinguish between natural and artificially produced FRBs</p> <p>03/20:  The beam would be shadowed by the sail, and maybe you would see fringes.  Also a repeater could be a signature of the relatively short acceleration and deceleration phase.</p> <p>Is ANITA unique is how much sky we can see at these frequencies with this sensitivity?</p> <p>Would the fact that we digitize so quickly help in distinguishing natural from artificial?</p> <p>Is there any time when ANITA is orientied in such a way that we look along the plane of the MW and thus see the whole galaxy?</p> <p>Can we extend analyses above horizontal and increase sensitivity that way?</p> <p>Can we look for reflections from the surface?</p> <p>Note that the signals would extend ~1 ms in time.</p> Encoding: HTML ELCode plain Suppress Email notification

Attachment 1:
Drop attachments here...

ELOG V3.1.5-fc6679b