Pulsar Overview Kevin Stovall NRAO IPTA 2018 Student Workshop, 11 June, 2018
Pulsars
Pulsars ~2,700 pulsars known Act as clocks, therefore provide a means for studying a variety of physical phenomena Strongly affected by the interstellar medium (ISM) There are many categories of pulsars (MSPs, RRATs, DNSs, mode-switching, nulling, etc.) As a population are steep spectrum sources (alpha~-1.4)
Some Pulsar Applications Populations Study of Interstellar Medium Neutron Stars Dispersion Supernovae / Massive Stars Scattering/Scintillation Binaries Faraday rotation Millisecond Pulsars (MSPs) Extreme Environments Exotic Systems Large B-field Double Neutron Stars (DNSs) Neutron Star Interior Triple Systems Tight Binary systems Double Pulsar Fast Spinning Pulsar-BH Theories of Gravity Clocks Tests of GR Time Standard Alternative Theories Gravitational Waves
Pulsars
Pulse Folding
Interstellar Medium Effects Dispersion Delay / DM 2 DM = R d 0 n edl From Essential Radio Astronomy, Condon & Ransom
Galactic Electron Density Lazio & Cordes, 2002, astro-ph:0207156 Yao, Manchester & Wang, 2017, ApJ, 835
Scintillation Arcs Scattering Scintillation From Handbook of Pulsar Astronomy, Lorimer & Kramer
ISM: Faraday rotation PPA = 2 RM R d RM = e3 2ıme 2c4 0 n eb dl hb i =1:23 G RM DM
Profile Temporal Stability
Pulsar Timing
P-Pdot Diagram
Millisecond Pulsars (MSPs) Spin periods less than ~10 ms, weaker magnetic fields, smaller spin-down rates primary secondary binary disrupts Supernova binary survives (b) runaway star young pulsar mildly recycled pulsar young pulsar Formed through accretion from a companion star secondary evolves (Roche Lobe overflow) X-rays high-mass system binary disrupts Supernova (therefore most of them are in low-mass system binary survives binaries: 2/3) millisecond pulsar - white dwarf binary double neutron star binary Lorimer, 2008, LRR, 11
Pulsar Spatial Distribution
Pulsar Sky Distribution
Pulsar Surveys (partial list) Survey Center Frequency (MHz) Bandwidth (MHz) Frequency Resolution (khz) Sample Time (us) Integration Time (s) Style Survey Region AO327 327 57/69 56/24 125/82 64 Drift All Arecibo Sky Dec. between -1 & 38 CRAFTS 600 400?? 40? Drift? GBNCC 350 100 24 82 120 Pointed All GBT Sky Dec above -40 deg HTRU-N/S 1352 340 391 64 4200/540/270 Pointed All Sky LOTAAS 143 32 12 492 3600 Pointed PALFA 1375 323 336 65 268/180 Pointed Northern Sky Dec > about 0 deg Galactic Plane in Arecibo Dec Range Arecibo 327 MHz Drift Survey (AO327) - Deneva et al. 2013, ApJ, 775, 51 The Commensal Radio Astronomy FAST Survey (CRAFTS) Green Bank North Celestial Cap (GBNCC) - Stovall et al. 2014, ApJ, 791, 67 High Time Resolution Universe - South (HTRU-S) - Keith et al. 2010, MNRAS, 409, 619 High Time Resolution Universe - North (HTRU-N) - Barr et al. 2013, MNRAS, 435, 2234 LOFAR Tied-Array All-sky Survey (LOTAAS) - Coenen et al. 2014, A&A, 570, 60 Arecibo L-Band Feed Array Pulsar Survey (PALFA) - Cordes et al. 2006, ApJ, 637, 446
Targeted Pulsar Searches Fermi Unassociated Gamma-ray sources Locations of gamma-ray sources are searched using various radio telescopes.
Drifting Subpulses & Nulling
Mode Changing
Rotating Radio Transients
B1913+16: First Binary Pulsar
Binary Parameters Keplerian Binary Parameters Orbital Period: PB Projected Semimajor axis: A1 Time of Periastron Passage: T0 Eccentricity: E Longitude of Periastron: OM
Post-Keplerian Parameters! =6ıf b (2ıMf b ) 2 3 (1 e 2 ) 1 = e(2ıf b ) 1 (2ıMf b ) 2 3 m 2 M (1 + m 2 M ) P b = 192ı 5 (2ı f b) 5 3 F (e) r = m 2 s = sin(i)
Double Pulsar GR Tests PSR J0737-3039A/B
Massive Pulsars & EOS PSR J1614-2230 Pulsar Mass = 1.97 +/- 0.04 Demorest et al. 2010, Nature, 467, 1081 PSR J0348+0432 Pulsar Mass = 2.01 +/- 0.04 Antoniadis et al. 2013, Science, 340, 448