Finding the next Galactic extragalactic FRB Dan Maoz Tel-Aviv University with Avi Loeb

WRONG!

All-sky rate of FRBs with flux >0.3 Jy: ~10,000 day/sky (Scholz+16) or ~3.65 million FRBs/year from volume within 2.4 Gpc (median z=0.64) that includes 600 million L* galaxies. If FRBs do not avoid L* galaxies, Milky Way should host one every 150 years (or 30-1500 years considering rate uncertainty).

FRB121102 has repeated for >4 years. Is its persistence special? Probably not! FRB110220 and FRB140514 appeared in same 14 arcmin-diameter Parkes beam. Petroff+15: 32% random probability  unrelated FRBs

FRB121102 has repeated for >4 years. Is its persistence special? Probably not! FRB110220 and FRB140514 appeared in same 14 arcmin-diameter Parkes beam. Petroff+15: 32% random probability  unrelated FRBs Maoz+15: 1%  99% it’s the same source, repeating >3 yrs DM goes from 945  562 pc/cm3

FRB from NS inside expanding SNR  changing DM

If FRBs persist for decades or centuries, an active FRB could be repeating in the Milky Way now. It is BRIGHT: 4 Gpc  10 kpc 0.3 Jy  30 GJy

Challenge: detect a ~30 GJy, ~1 ms, dispersed pulse that occurs somewhere in the sky, maybe once a week or month? Thornton+13 t ~ f-2

If FRBs repeat for decades or centuries, an active FRB could be repeating in the Milky Way now 4 Gpc  10 kpc 0.3 Jy  30 GJy Flux levels and frequencies (e.g. 2.4 GHz) of cellular communication

Option 1: Use some of 7 billion cellphones on Earth as receivers. *Free downloadable Citizen Science application listens in background for FRB-like signal by analyzing raw radio signal. Can do efficient real-time de-dispersion search (Zackay & Ofek 2017) over cellphone bandpass. *GPS time-stamp and record candidate events. *Upload list of candidate events and the phone’s location to central website.

dt ET events will be detected near-simultaneously by many receivers. Arrival-time differences  triangulation of source direction GPS time accuracy: 100 ns Earth light-crossing time : ~20 ms Localization precision: 5x10-6 ~ 1 asec DM compared to Galactic DM model  Source distance dt Problem: raw signal may be inaccessible to applications

Option 2: Analyze raw broad-band signal from cell-phone’s FM tuner Problem: ~100 MHz probably not a good place for FRB search

Option 3: Deploy global network of software defined radios (SDRs)

STARE results: 18 months: 4 million pulses at 611 MHz. Only 4000 coincident among the 3 receivers. Associated with 99 events. All associated with solar flares.  Concept works (GPS time stamp, localization)  RFI is manageable (at least was, 20 yrs ago, at 600 MHz)

Conclusions If FRBs do not avoid Milky-Way-like galaxies, MW hosts a 30 GJy FRB every 30-1500 yrs (and Local Group galaxies host MJy FRBs). If some or all FRBs repeat for decades-centuries, a MW FRB may be active now. Simple and cheap networks of cellular devices (phones, PCs) can detect and localize a MW FRB, which will allow identifying and studying the FRB source in unique detail.