Neutron Stars

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Neutron Stars

Department of Physics & Astronomy Stony Brook University

J.M. Lattimer, Open Nights, 9/7/2007 – p.1/25 J.M. Lattimer, Open Nights, 9/7/2007 – p.2/25 lowing down, ruling s. . Type II supernovae. the Lt.). tron star. s as end products of on star. cluding the Crab pulsar, lds. not dly rotate. utron stars. on star. Daily Telegraph discover the pulsar PSR 1919+21, Aug 6.

Pulsars: The Early History Hewish, Bell, Pilkington, Scott and Collins supernovae. using secret military radar in Alaska. out binary models. This also clinched their connection with 1932 Chadwick discovers the neutron. 1934 W. Baade and F. Zwicky predict existence of neutron star 1939 Oppenheimer and Volkoff predict upper mass limit of neu 1964 Hoyle, Narlikar and Wheeler predict neutron stars rapi 1966 Colgate and White suggest supernovae make neutron star 1964 Prediction that neutron stars have intense magnetic fie 1966 Wheeler predicts Crab nebula powered by rotating neutr 1967 Pacini makes first pulsar model. 1967 C. Schisler discovers a dozen pulsing radio sources, in 1968 Pulsar discovered in Crab Nebula, and it was found to1968 be T. s Gold identifies pulsars with magnetized, rotating ne 1968 The term “pulsar” first appears in print, in the 1969 “Glitches” provide evidence for superfluidity in neutr 1967 1971 Accretion powered X-ray pulsar discovered by Uhuru ( years. in gamma rays J.M. Lattimer, Open Nights, 9/7/2007 – p.3/25 r. It shows the orbital tation rate, 716 Hz. er’s supernova) comes s not). 39, by Hessels. sleevage.com/joy-division-unknown-pleasures/ , for PSR J1903+0327 ⊙ by Joy Division Unknown Pleasures

Pulsars: Later Discoveries (#19/100 greatest British albums ever). discovered by Backer, Kulkarni, et al. at Arecibo. orbiting PSR B1257+12 by Wolszczan and Frail. lowest known dispersion measure andpossibly is the closest known pulsar. decay due to gravitational radiationby predicted Einstein’s General Theory of Relativity. album cover for from magnetar SGR 1806-20. It was brighter than the full moon and more energy was released in 0.1 s than Sun emits in 100,000 1974 Binary pulsar PSR 1913+16 discovered by Hulse and Taylo 1974 Hewish awarded Nobel Prize (but Jocelyn Bell Burnell wa 1982 First millisecond pulsar, PSR B1937+21, 1992 Discovery of ﬁrst extra-solar planetary system 1992 Prediction of magnetars (Duncan &1993 Thompson). Hulse and Taylor receive Nobel1994 Prize. Discovery of PSR J0108-1431 which has the 2004 Largest burst of energy in our Galaxy since SN 1604 (Kepl 1979 Chart recording of PSR 1919+21 used as 2004 Discovery of PSR J1748-2446ad with the highest known ro 2005 Discovery of ﬁrst binary2009 with Measurement two of pulsars, largest PSR mass, J0737-30 1.67 M sleevage.com/joy-division-unknown-pleasures/

J.M. Lattimer, Open Nights, 9/7/2007 – p.4/25 . . s, according 3 / 2 033 « . nergy. π P – from orbital 2 sistent with a = 0 bject except a second. J.M. Lattimer, Open Nights, 9/7/2007 – p.5/25 „ smaller period. P 3 equency of oscillation. / 1 ars. ) AU = 93 miles 6 − GM 10 · =( 0 . and a period of equal to max = 1 a R ⊙ 3 M / ⇒ 2 « = 1 P M 2 max 1 year GM R an object could have and still spin that fast without „ 3 = / 1 max km. Again, only a neutron star or black hole works. « R max ⊙ R M M = 15 2 « „ π P = 2 max a R „

Pulsars: What are they? shedding mass from the equator is found from motion, vibrations or spin. The Crab pulsar bursts 30 times a spinning object and rules out orbiting stars or vibrating st Small source period can only be explained by compact objects A binary star with total mass of The maximum radius There is no known mechanism for blackThe holes discovery to that emit the pulses Crab of pulsar e is slowing down is onlyA con binary that is losing energy goesA into vibrating a object tighter that orbit is with losing a energy develops a higher fr This gives This separation is smaller thanneutron the star radius or of black any hole. solar mass o to Kepler’s Law, would have a separation • • • • • • • speed of light. It utrinos become s the Moon. llium barium 1083 km/s J.M. Lattimer, Open Nights, 9/7/2007 – p.6/25 ce the Big Bang: t 3 ocity can be measured. − g cm ), at 138 K. G 15 15 125 billion K 10 O 45 = 10 Hz = 10 Cu B c 30 T Ca 2 = 716 − 30 ν Ba 3 cm s l T 14 12 10 billion K .

Amazing Facts About Neutron Stars = 700 T is actually an underestimate, since only the transverse vel Densest objects this side ofFour an teaspoons, event on horizon: the Earth’s surface, wouldLargest weigh surface as gravity: much a This is 100 billion times the Earth’sFastest gravity. spinning objects known: This spin rate was measuredlocated for in PSR the J1748-2446ad, globular which cluster is Terzan 5 located 28,000 ligh Largest known magnetic ﬁeld strengths: The Sun’s ﬁeld strength is about 1Highest G. temperature superconductor: The highest known superconductor on the Earth is mercury tha Highest temperature, at birth, anywhere in the Universe sin Fastest measured velocity of aThis massive velocity object was in measured the for Galaxy: PSR B1508+55, and is 1/300 the The only place in the universe except for the Big Bang where ne years away. (33 pulsars have beenIf found the in radius this is cluster.) aboutis 15 one km, fourth the the velocity speed at of the light. equator calcium copper oxide (Hg trapped • • • • • • • • es to be several by Lorimer and Kramer J.M. Lattimer, Open Nights, 9/7/2007 – p.7/25 ital poles (magnetic s and light are emitted Handbook of Pulsar Astronomy From sG ˙ P / 4 P − P q 6 19 R 2 10 B ˙ P ∝ ˙ 3 2 P > − − rot P P ˙ is the characteristic age E 2 2 MP ) ˙ = p P 2 MR MR (2 − /dt ∝ ∝ R P/ Pulsars: Why do they pulse? rot ∝ = rot rot ˙ τ E dipole model). The beam widthsdegrees, have so been we measured are in fortunateany some to given cas see pulsar. For everythere one must we be see, several others we don’t. All models involve the lighthouse effect, in which particle It is known that spinningdipoles magnetic can emit energy. Nobody understands in detail how the beaming is accomplished. For the magnetic dipole model, dE E from magnetic poles that are usually misaligned with the orb B • • • • > P ———————————–> diagram. ˙ P − P J.M. Lattimer, Open Nights, 9/7/2007 – p.8/25

in terms of the period ————————————–

——————————————————— <

Diagram ˙ P , it is useful to plot the positions of pulsars in a ˙ P − P

The This is the H-R diagram for pulsars. Since the magnetic field strength and the age can be expressed and the spin-down rate J.M. Lattimer, Open Nights, 9/7/2007 – p.9/25 0.gif, J.M. Lattimer, Open Nights, 9/7/2007 – p.10/25 Artist’s conception s, on the night of August 27, commons.wikimedia.org/wiki/Image:Magnetar-3b-450x58 Hz). 100 > -ray emission) stop. γ G Magnetars – Extreme Neutron Stars 15 10 ∼ Anticipated in 1992 by Duncan & Thompson Characterized by superstrong magnetic fields, B Likely physical explanation for softrepeaters gamma (SGRs) and anomalous X-ray pulsars (AXPs) Superstrong fields lead to strongrotation braking rate, of which the is observed. Estimates are that 1 inmagnetar 10 rather supernovae than produces a a normal neutron star. Strong fields generated by aglobally-extending, convection-driven, dynamo in the proto-neutron star if the rotation rate is fast enough ( Strong fields decay within 10,000(X-ray years and and activity Given the observed number ofcould magnetars, be there 30 million orthe more Galaxy. dead magnetars in SGR 1900+14, despite its large1998, distance ionized of ionospheric 20,000 atoms light to year daytime levels. Most proto-neutron stars rotate much less rapidly. • • • • • • • • • J.M. Lattimer, Open Nights, 9/7/2007 – p.11/25 Hubble

The Crab Pulsar NASA/ESA J.M. Lattimer, Open Nights, 9/7/2007 – p.12/25 Chandra X-ray observatory 1990 MJD 1980

The Vela Pulsar 1970

40000 45000 50000 −5 −5 Link, Epstein and Lattimer Glitches (starquakes) are sudden jumpsrotation in rate. They occur insimilar a to pattern Earthquakes and couldrelated be to superﬂuidity inside the star.

1X10 2X10 cumulative angular momentum angular cumulative J.M. Lattimer, Open Nights, 9/7/2007 – p.13/25 tional radiation. in 280 million years. Such Weisberg & Taylor 4 . ⊙ . ◦ and 2 . 47 per year; 0002 ◦ . 2 0 . 4 ± 4414 . 1 . 0002 .

The Binary Pulsar PSR 1913+16 0 ± 3867 . In one day this isadvance the in same a as century. Mercury’s. Found by Hulse and Taylor in 1974. Binary period is 7.75 hours. Pulsar period is 59 ms. Eccentricity is 0.617. Advance of the periastron is Orbit is inclined in plane ofSeparation sky of by stars varies from 1.1 toMasses 4.8 of R stars are The orbit’s period is shrinking.00008 by seconds per year. The separation of the system3.5 is meters shrinking per by year. The binary will merge inevents a are violent expected collision to of be neutron the stars most intense sources of gravita 1 • • • • • • • • • • • Lyne et al., Science 303 (2004) 1153 J.M. Lattimer, Open Nights, 9/7/2007 – p.14/25 ar B, allowing the ar. ere for the ﬁrst time. in 85 million years, more than e moment of inertia pulsar A. . ◦ 9 . . and per year, 88 ⊙ ◦ 9 . 005 . 0 16 ± 337 . 1 . 005

The Pulsar Binary PSR J0737-3039 . 0 ± 250 . four times as large as for PSR 1913+16. Found by the Parkes radio telescope inA 2004. more extreme version of PSRBinary B1913+16. period is 2.5 hours. Pulsar periods are 22.7 ms andEccentricity 2.77 is s. 0.088. Advance of the periastron is Orbit is inclined in plane ofSeparation sky of by stars is about 1.4 R Masses of stars are The orbit’s period is shrinking.00004 by seconds per year. The separation of the system is shrinkingThe by binary 2.5 will meters merge per in3 ye a times violent less collision than of for neutron PSR stars The 1913+16. beam of pulsar A passes through the magnetosphere of puls A remote possibility exists to measure, for the ﬁrst time, th possibility of mapping the structure of a pulsar magnetosph 1 • • • • • • • • • • • • • • ally an occasional in this case a type s material accretes J.M. Lattimer, Open Nights, 9/7/2007 – p.15/25 r. The ﬁrst time the rsts that are also apidly rotating, 998 by Colleen about 13,000 light years away. ⊙ science.nasa.gov/newhome/headlines/ast11dec981.htm

The Burping Pulsar sporadically ejects matter which formspulsar a sweeps disc through around the the disc sta a large outburst is produced a It is a rare example of a pulsar orbiting a massive companion,The pulsar’s period is 15.8 seconds, but it has additional bu The natural explanation is that the B[e] star, which is very r B[e] star, which is a very hot blue star with 8–15 M regularly spaced but on alarge much burst longer followed timescale. by There a is series usu of smaller outbursts. onto the neutron star. The smaller outbursts occur as the pulsar continues to pass through the disc once oran twice orbit. Gradually, the disc is swept clean and thediminish. bursts • • • One of the stranger pulsarsWilson-Hodge is at PSR NASA’s J1946+274, Marshall discovered Space in Flight 1 Center. Dany Page, UNAM

J.M. Lattimer, Open Nights, 9/7/2007 – p.16/25 J.M. Lattimer, Open Nights, 9/7/2007 – p.17/25 Hz Hz = 1122 = 716 XTE J1739-285 ν Kaaret et al. 2006 Not conﬁrmed to be a rotation rate PSR J1748-2446ad ν Hessels et al. 2006 J.M. Lattimer, Open Nights, 9/7/2007 – p.18/25

Constraints from Pulsar Spins - maximum mass ) J.M. Lattimer, Open Nights, 9/7/2007 – p.19/25 p

) - 2 +

ǫ - )( 3 Gm/c 2 πpr − r + 4 ( r 2 m r ( 2 ǫ 2 c G c π − = 4 = dr dp dr dm

Neutron Star Structure Tolman-Oppenheimer-Volkov equations J.M. Lattimer, Open Nights, 9/7/2007 – p.20/25 ROSAT image – F. Walter

RX J1856-3754 – The Stony Brook Neutron Star d - km/s from 190 ≃ ) d this to J.M. Lattimer, Open Nights, 9/7/2007 – p.21/25 v pc using same data 1996-1999 HST pixel size 40 parallactic ellipse pc and ± 12 ± = 140 D = 117 D , Kim & Lattimer β pc based on 2002-2004 High-Resolution Camera of the Advance pc with 8 16 ± ± 115

Astrometry of RXJ 1856-3754 ≃ = 161 (2010, in preparation) determined D Walter & Lattimer (2002) determined Star’s age is probably 0.5 million years Kaplan, van Kerkwijk & Anderson (2002): van Kerkwijk & Kaplan (2007, conference proceeding) revise Walter, Eisenbei D 2002-2004 HST data Camera for Surveys HST observations (double the resolution 1996-1999 HST Planetary Camera observations • • • • • J.M. Lattimer, Open Nights, 9/7/2007 – p.22/25

Cas A Cas A J.M. Lattimer, Open Nights, 9/7/2007 – p.23/25 Wikipedia, from NASA

X-ray binary ×10-3 0.001 0.45 2.4 2.4 2.4 2.4 0.0014 0.4 2.2 RXJ 1856 2.2 M13 2.2 2.2 ω Cen 0.0008 0.0012 0.35 2 2 2 2 0.3 0.001 1.8 0.00061.8 1.8 1.8 ) ) ) ) 0.25 0.0008 1.6 1.6 1.6 1.6 0.2 M (M M (M M (M M (M 0.0004 0.0006 1.4 1.4 1.4 1.4 0.15 0.0004 1.2 1.2 1.2 1.20.1 0.0002 1 1 0.00021 X7 0.051

0.8 0 0.8 0.80 0.80 6 8 10 12 14 16 18 6 8 10 12 14 16 18 6 8 10 12 14 16 18 6 8 10 12 14 16 R (km) R (km) R (km) R (km)

J.M. Lattimer, Open Nights, 9/7/2007 – p.24/25 10 100 80 60 40 20 0 × >>R ph r R (km) J.M. Lattimer, Open Nights, 9/7/2007 – p.25/25 Steiner, Lattimer & Brown 2010 6 8 10 12 14 16 18

1 2

2.5 1.5 0.5 ) (M M 3 10 180 160 140 120 100 80 60 40 20 0 × >>R ) 3 ph r (MeV/fm ε

Bayesian TOV Inversion 200 400 600 800 1000 12001400 1600 1800

3 2

P (MeV/fm P 10 ) 10 3