Neutron Stars Neutron Stars Discovery of neutron 1932

Neutron Stars

Neutron Stars • Discovery of neutron (1932) • Neutron Star (1934) – Landau (unpublished) – Baade & Zwicky “With all reserve we advance the view that supernovae represent the transitions from ordinary stars into neutron stars, which in their final stages consist of extremely close packed neutrons” • Oppenheimer & Volkoff (1938) • Recognition of the importance of accretion power (Salpeter, …) in early sixties

References • Padmanabhan (Volume 2) • Shapiro Teukolsky • Lattimer & Prakash Science (astroph/0405262) – This is an excellent review • Kaspi et al. (astroph/0402136) – Good phenomenological review • Kaplan 2004 Ph. D thesis – For local flavour

Manifestations of NS

Manifestations of Neutron Stars • • • Low Mass X-ray Binaries (Rocket Flt, Sco X-1) Pulsars (IPS Array, CP 1919) High Mass X-ray Binaries (UHURU, Cen X-3? ) Binary Pulsars (Arecibo, 1913+16) Soft gamma-ray repeater (Satellites, 5 March 1979) Millisecond Pulsars (Arecibo, 1937+214) Cluster Pulsars (Jodrell Bank, M 28) Anomalous X-ray Pulsars (Einstein, 1 E 2259) Thermally emitting NS (ROSAT, RXJ 1856) Enigmatic source in Cas A (Chandra)

A Young Pulsar in G 11. 2 -0. 3

Of Crabs, Shells and Plerions

Pulsar P-Pdot Diagram

Nearby X-ray NS • Cooling NS • Middle-aged magnetars (decay of B field) • Accreting from ISM (see Accretion lecture)

Magnetic Fields Cyclotron Frequency omega = e. B/mc Electron cyclotron: nu = 3 Hz B(micro Gauss) Energy = 10 ke. V (B/1012) G BQED = 4 x 1013 Gauss

Magnetic Fields • Cyclotron lines in accreting pulsars (usually confirmed by harmonics) • Features in nearby X-ray bright NS (confused state of affairs) – Some are interpreted as proton cyclotron – Features are broad in some cases See review by Kaspi et al. [astroph/0402136]

Masses of Neutron Stars

Neutron Star Masses

Radius (Rotation) of NS

Coherent Oscillations from LMXBs

Maximum Spin Rate 642 Hz: Is this the limiting period? • Neutron stars cannot be spun up (grav radiation -> LIGO) • Limiting period is fundamental to the equation of state of dense matter

Radius of NS: constraints from spin period

Formation of NS

Do most SN produce NS?

Enigmatic Source in Cas A

What is in the center of SN 1987 A?

Kaplan’s thesis: what is in the centers of shells?