1. Pulsar search and timing Pulsar search and timing 22/10/2011 INDIGO discussions@IUCAA Bhal Chandra Joshi Bhal Chandra Joshi

2. Radio pulsar searches Radio pulsars - highly magnetized rotating NS - compact - periodic pulses - periodic pulses Motivation – 10 5 pulsars – exotic systems relevant to GR and GW Searches - 5 dimensional – RA, Dec, DM, P, Pdot - blind and targetted Analysis - Similarity with GW searches - highly compute intensive - DM and resolution (k chan 10 ns) – HPC - highly compute intensive - DM and resolution (k chan 10 ns) – HPC - code involves ~ algorithm - harmonic analysis, matched filter, chirp - code involves ~ algorithm - harmonic analysis, matched filter, chirp - interference rejection - RFI - interference rejection - RFI - differences - DM search, resolution, integration time, templ match etc. - differences - DM search, resolution, integration time, templ match etc. - GMRT searches code implemented on 72-node dual processor HPC(up) - GMRT searches code implemented on 72-node dual processor HPC(up) Searches - PKSMB - 1000 pulsars - Parkes - PHMB - 20 pulsars - Parkes - DPSR - PHMB - 20 pulsars - Parkes - DPSR - GMLPSR - 3 pulsars - GMRT - GMLPSR - 3 pulsars - GMRT -GMGPPTS - 1 pulsar - GMRT -GMGPPTS - 1 pulsar - GMRT - other GMRT surveys - other GMRT surveys Goals - Normal pulsars, transient intermittant pulsars, high magnetic field PSR MSPs, binaries - NS-NS and NS-BH - relevance for GW community

3. Pulsars for GR and GW Double Pulsar - J0737-3039 – two radio pulsars 22 ms and 2.7 s (Burgay et al. 2003;Lyne et al. 2004) - tight (2.5h) edge-on mildly elliptical orbit - eclipses of A and BP of B - tight (2.5h) edge-on mildly elliptical orbit - eclipses of A and BP of B -sharp pulses of MSP and Shapiro delay of A and B – best GR test -sharp pulses of MSP and Shapiro delay of A and B – best GR test - evolution of light curves B and A - geodetic precession - evolution of light curves B and A - geodetic precession - monitored at GMRT - no pulsar B now !! - monitored at GMRT - no pulsar B now !! Pulsar Timing Array for nH gravity waves - clock like stability - long time – nHz Sources - SMBH, Sources - SMBH, cosmic strings, cosmic strings, inflation inflation

4. - Most of our knowledge of radio pulsars is derived from pulsar timing studies - Pulsars are timed by associating a Time of Arrival (TOA) at the solar system barycenter to their integrated profiles - Pulsars are timed by associating a Time of Arrival (TOA) at the solar system barycenter to their integrated profiles - Comparison with model,.e.g. Constant period P Pulsar Timing -Timing Capability of GMRT has been recently established ~ 20 us residual - New pulsars discovered with GMRT are now being timed at GMRT -A project to measure DM variations of MSPs is ongoing -Search for new MSPs - better clocks than about 100 MSPs discovered so far - Aim of PTA to have an ensemble of 20 MSPs with residuals of 1 ns ( 2 100 ns) -Timing precision increases with time - Intensive timing campaign -involving 8 telescopes worldwide (2 USA, 4 Europe, 1 Australia, 1 India)

5. Instrumentation development -High Time resolution timing - coherent dedispersion - smear in ISM -PSBR - software baseband pulsar backend -Upgrade of GMRT - wideband feeds & wideband backend - - improvement of sensitivity - - new feed design and digital hardware -GMRT Antenna control system upgrade - - improve the quality of GMRT images by better tracking - errors - - research in new control algorithms - - QFT feeback with FEM modeling of antenna structure - - collaborative effort with BARC – EIG, academic Institutions in India and USA Future - SKA - 2020 ?

6. Thank you