Kevin Stovall NRAO

IPTA 2018 Student Workshop, 11 June, 2018

Pulsar Overview

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

•Neutron Stars •Supernovae / Massive Stars •Binaries •Millisecond Pulsars (MSPs)

Exotic Systems•Double Neutron Stars (DNSs) •Triple Systems •Double Pulsar •Pulsar-BH

Clocks•Time Standard

Study of Interstellar Medium•Dispersion •Scattering/Scintillation •Faraday rotation

Extreme Environments•Large B-field •Neutron Star Interior •Tight Binary systems •Fast Spinning

Theories of Gravity•Tests of GR •Alternative Theories •Gravitational Waves

Pulsars

Pulse “Folding”

Interstellar Medium Effects

From “Essential Radio Astronomy”, Condon & Ransom

DM =R d0 nedl

Delay / DM ⌫�2

Dispersion

Galactic Electron Density

Yao, Manchester & Wang, 2017, ApJ, 835Lazio & Cordes, 2002, astro-ph:0207156

Scintillation Arcs

From “Handbook of Pulsar Astronomy”, Lorimer & Kramer

Scattering Scintillation

ISM: Faraday rotation� PPA = –2 ⇥ RM

RM = e3

2ım2ec

4

R d0 neB||dl

hB||i = 1:23—G RMDM

Profile Temporal Stability

Pulsar Timing

P-Pdot Diagram

Millisecond Pulsars (MSPs)

• Spin periods less than ~10 ms, weaker magnetic fields, smaller spin-down rates

• Formed through accretion from a companion star (therefore most of them are in binaries: 2/3)

mildly recycled pulsar

X-rays

runaway star

young pulsar

primary

millisecond pulsar - white dwarf binary

binary disrupts

double neutron star binary

binary disrupts

young pulsar

secondary

binary survives

secondary evolves(Roche Lobe overflow)

binary surviveslow-mass system

Supernova

Supernovahigh-mass system

(b)(a)

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 Northern Sky Dec > about 0 deg

PALFA 1375 323 336 65 268/180 Pointed 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 SearchesFermi 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 ParametersOrbital Period: PB

Projected Semimajor axis: A1 Time of Periastron Passage: T0

Eccentricity: E Longitude of Periastron: OM

Post-Keplerian Parameters

! = 6ıfb(2ıMfb)23 (1� e2)�1

‚ = e(2ıfb)�1(2ıMfb)23m2M (1 + m2

M )

Pb = � 192ı5 (2ı—fb)

53 F (e)

r = m2

s = sin(i)

Double Pulsar GR TestsPSR J0737-3039A/B

Massive Pulsars & EOSPSR J0348+0432 Pulsar Mass = 2.01 +/- 0.04 Antoniadis et al. 2013, Science, 340, 448

PSR J1614-2230 Pulsar Mass = 1.97 +/- 0.04 Demorest et al. 2010, Nature, 467, 1081