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

Ab44292d7d6f032baf342a98230a6654?s=47 transientskp
January 08, 2014

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

Gosia Pietka

Ab44292d7d6f032baf342a98230a6654?s=128

transientskp

January 08, 2014
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  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. 2 Minute RSM Snapshots TraP Transient Candidate #929 July 13,

    17.14 July 13, 17.16
  12. #929 Detection in 10s Images

  13. #929 Detection in 10s Images

  14. 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.
  15. 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 ...
  16. 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