Millisecond pulsar population andrelated high energy phenomena王伟(NAOC)July2009,Pulsar Summer School Beijing
Millisecond pulsar population and related high energy phenomena 王 伟 (NAOC) July 2009, Pulsar Summer School Beijing
ContentsIntroduction to millisecond pulsars (MSPs);High energy emissions in MsPs: observationsversus theories; Millisecond pulsar population in the GalacticCenter (GC)High energy contributions by MSPs toward theGC
Contents • Introduction to millisecond pulsars (MSPs); • High energy emissions in MSPs: observations versus theories; • Millisecond pulsar population in the Galactic Center (GC) • High energy contributions by MSPs toward the GC
FormationscenarioofMSPsWhat are MSPs (?):Observations(inradioandX-rays):compactobjectswithveryfastspin,P<30ms,ie,pulsars, derived dipolemagnetic fields<1010 G;Theories(formationchannel):oldneutronstarsinthelowmassX-raybinaries(LMxB)arerecycledtomillisecondperiodsthroughaccretions.Theircurrentpopulationlikelyconsistsofneutronstarsinisolation(havingevaporatedtheircompanions)andinLMXBs.- Very old (>10° yr) and fast-spin (P<30 ms)pulsars -Thespinequilibriumofneutronstarsinlow-massX-raybinaries:Peg = 3.0(B/10°)6/7(R/10km)18/7(M /1.4M。)-5/7(M/ Meda)-3/7 msObservedspinperiod(fastestuptonow):PSRB1957+200.0016074 sPSRB1937+210.0015578 sPSRJ1748-2446ad0.0013966s(Terzan5)
Formation scenario of MSPs P B R k m M M M M ms eq edd 9 6/7 18/7 5/7 3/7 3.0( /10 ) ( /10 ) ( /1.4 ) ( / ) − • • − = The spin equilibrium of neutron stars in low-mass X-ray binaries: What are MSPs (?): Observations (in radio and X-rays): compact objects with very fast spin, P<30 ms, i,e, pulsars, derived dipole magnetic fields < 1010 G; Theories (formation channel): old neutron stars in the low mass X-ray binaries (LMXB) are recycled to millisecond periods through accretions. Their current population likely consists of neutron stars in isolation (having evaporated their companions) and in LMXBs. - Very old (>108 yr) and fast-spin (P<30 ms) pulsars - Observed spin period (fastest up to now ): PSR B1957+20 0.0016074 s PSR B1937+21 0.0015578 s PSR J1748-2446ad 0.0013966 s (Terzan 5 )
P-P diagram(circles:binaries)Whatis therealistic101%CformationchannelofMsPsfromnormalneutronstarsinLMXBs?NoconfidentevidencefortheT-transition-statesources1010before2008Anumberofmildlyrecycledbinarypulsarspossiblyfound.Parkes MB surveyParkes PH surveyThischannelconfirmedby+Swinburne MB surveyOther disk pulsarsrecent discovery:a radio MsP☆ X-ray and -rayinaLMXB(Archibaldetal.2009):PSRJ1023+0038log[Period (s)]P=1.69ms
P – P diagram (circles: binaries) What is the realistic formation channel of MSPs from normal neutron stars in LMXBs? No confident evidence for the transition-state sources before 2008 A number of mildly recycled binary pulsars possibly found. This channel confirmed by recent discovery: a radio MSP in a LMXB (Archibald et al. 2009): PSR J1023+0038, P=1.69 ms
MSPdistributioninthe GalaxyObserved MSPs in the GalaxyTwopopulationsofMSPsfromthepresentobservations:Globularclusters10>Galacticfield47TucSNGC6266TwoglobularclustersinthebulgeTer511×[kpa]
Two populations of MSPs from the present observations: ➢ Globular clusters ➢ Galactic field 47Tuc Ter5 NGC6266 Two globular clusters in the bulge MSP distribution in the Galaxy