Finding the next Galactic extragalactic FRB Dan Maoz

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

! G N W O R

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).

FRB 121102 has repeated for >4 years. Is its persistence special? Probably not! FRB 110220 and FRB 140514 appeared in same 14 arcmindiameter Parkes beam. Petroff+15: 32% random probability unrelated FRBs

FRB 121102 has repeated for >4 years. Is its persistence special? Probably not! FRB 110220 and FRB 140514 appeared in same 14 arcmindiameter 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/cm 3

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 dedispersion 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.

ET events will be detected near-simultaneously by many receivers. Arrival-time differences triangulation of source direction GPS time accuracy: 100 ns dt Earth light-crossing time : ~20 ms Localization precision: 5 x 10 -6 ~ 1 asec DM compared to Galactic DM model Source distance 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.