Upgrade to Pro — share decks privately, control downloads, hide ads and more …

So are there counterparts to the NCP transient ...

Avatar for transientskp transientskp
January 08, 2014

So are there counterparts to the NCP transient in the HBA/RSM data?

Gosia Pietka

Avatar for transientskp

transientskp

January 08, 2014
Tweet

More Decks by transientskp

Other Decks in Science

Transcript

  1. So are there counterparts to the NCP transient in the

    HBA/RSM data? G. Pietka, R. Fender, T. Hassall, A. Stewart Amsterdam, January 8, 2014
  2. RSM low DM directions • Concentrate search for FRBs to

    RSM pointings with a low DM • This means 7 out of 48 pointings ~ 220 deg2 • 6 Zenith scans • 2 x 10 min snapshots per scan. An ideal low DM RSM strip
  3. RSM low DM directions • RSM short-timescale imaging • Using

    one band (149 MHz) out of the 4 used in the RSM. • Eg. 2 Mins 6 Zenith scans x 2 snapshots x 5 (2min) epochs = 60 x 2min epochs An ideal low DM RSM strip
  4. Estimating FRB Rates in RSM ν NCP =60 MHz t

    NCP =660s ν RSM =149 MHz t∼ν−4 ⇒ t RSM =17s 25 Jy FRB candidate lasting 11 minutes found in NCP data at 60 MHz: At the frequency of RSM data, the pulse width will be scaled according to the scatter broadening: Assume NCP Transient is Real (and duration was scattering-dominated):
  5. FRB Rates in 10s RSM Images FoV NCP =175deg2 Nr

    of epochs NCP =1897 FoV RSM =219deg2 Nr of epochs RSM =720 Flux limit = 4 Jy Flux limit =1Jy R RSM (1Jy) = 219deg2×720 epochs 175deg2×1897 epochs ×( 1Jy 4 Jy ) −3/2 =3.8 R∝F−3/2 α=0 First for spectral index , 25 Jy NCP source will be 25 Jy also in the RSM data. So we would expect 3.8 NCP-Like transients in 10s RSM Low DM search
  6. FRB Rates in 10s RSM Images R RSM (1Jy) =3.8×[(

    ν NCP ν RSM ) α ] −3/2 =3.8×f R∝F−3/2 Take the range of spectral index values -3 ≤ α ≤ 0 Expected number of NCP-Like transients in 10s RSM Low DM search for a range of spectral index values α f RSM Rate 0 1 3.8 -1 0.25 0.97 -2 0.065 0.248 -3 0.017 0.063
  7. FRB Rates in 10s RSM Images α=−3 For spectral index

    F NCP =25 Jy F RSM =1.63 Jy Source at the RSM detection limit of 1 Jy in the NCP band will be 15 Jy bright. R RSM (1Jy) = 219deg2×720 epochs 175deg2×1897 epochs ×R NCP(15Jy) N NCP(15Jy) =N NCP(4Jy) ×( 15 4 ) −3/2 N NCP(15Jy) =0.14
  8. FRB Rates in 10s RSM Images R RSM (1Jy) =

    219deg2×720 epochs 175deg2×1897 epochs ×0.14 R RSM (1Jy) =0.07 For the spectral index α=−3
  9. FRB Rates in 2min RSM Images R RSM (1Jy) =

    219deg2×60 epochs 175deg2×1897 epochs ×( 1Jy 4 Jy ) −3/2 =0.3 α=0 For spectral index However, there are other possible transient candidates in 2 minute images...
  10. 2 Minute RSM Snapshots TraP Transient Candidate #929 July 13,

    17.14 July 13, 17.16 Example of type of events reported by TraP that need to be tested and understood
  11. Deep 10 Minute Image of the Field • No source

    visible in deeper 10 minute image. • But artifacts in short time scale imaging not well understood.
  12. Conclusions • ~20s time scale NCP like events expected in

    the RSM field • Rate of NCP like events in a spectral index range -3 and 0 expected in the RSM low DM 10 s data: 0.07 - 4 • Possible transient candidate selected by TraP in the RSM data • More tests need to be done ...
  13. If No Transients in RSM Data Rate=− −ln 0.05 FoV

    ×Nr of epochs Rate 10s =− −ln 0.05 FoV ×Nr of epochs =− −ln 0.05 219deg2×720 =1.9×10−5 deg−2 Rate 2mins =− −ln 0.05 FoV ×Nr of epochs =− −ln 0.05 219deg2×60 =2×10−4 deg−2