New adventures of Uncatchables Sergei Popov SAI MSU
New adventures of Uncatchables Sergei Popov SAI MSU (astro-ph/0609275 and work in progress)
Plan of the talk Ü Ü 1. 2. 3. Ü Ü Intro. Pop. synthesis Some old results Two tests New improvements Initial distribution Mass spectrum and abundances ISM distribution Maps Age and distance distributions Where to search? Final conclusions 2
Good old classics The pulsar in the Crab nebula A binary system 3
The new zoo of neutron stars During last 10 years it became clear that neutron stars can be born very different. In particular, absolutely non-similar to the Crab pulsar. o Compact central X-ray sources in supernova remnants. o Anomalous X-ray pulsars o Soft gamma repeaters o The Magnificent Seven o Unidentified EGRET sources o Transient radio sources (RRATs) …. 4
Main reviews Труды ГАИШ том 72 (2003) • NS basics: physics/0503245 • SGRs & AXPs: astro-ph/0406133 • Magnetars: -Observations AXPs SGR - Theory astro-ph/0610304 astro-ph/0608364 astro-ph/0504077 • Central compact X-ray sources in supernova remnants: astro-ph/0311526 • The Magnificent Seven: astro-ph/0609066 • RRATs: astro-ph/0608311 • Cooling of NSs: astro-ph/0508056 http: //xray. sai. msu. ru/~polar/sci_rev/ns. html 5
Isolated neutron stars population: in the Galaxy and atq the backyard INSs appear in many flavours Radio pulsars AXPs SGRs CCOs RINSs RRATs q Local population of young NSs is different (selection) n. Radio pulsars n. Geminga+ n. RINSs 6
Evolution of NSs. I. : temperature [Yakovlev et al. (1999) Physics Uspekhi] First papers on thermal evolution appeared already in early 60 s, i. e. before the discovery of radio pulsars. 7
Evolution of neutron stars. II. : rotation + magnetic field Ejector → Propeller → Accretor → Georotator 1 – spin down 2 – passage through a molecular cloud 3 – magnetic field decay See the book by Lipunov (1987, 1992) astro-ph/0101031 8
Magnetorotational evolution of radio pulsars Spin-down. Rotational energy is released. The exact mechanism is still unknown. 9
Close-by radioquiet NSs Ü Discovery: Walter et al. RX J 1856. 5 -3754 (1996) Ü Proper motion and distance: Kaplan et al. Ü No pulsations Ü Thermal spectrum Ü Later on: six brothers 10
Magnificent Seven Name RX 1856 RX 0720 RBS 1223 RBS 1556 RX 0806 RX 0420 RBS 1774 Period, s 7. 05 8. 39 10. 31 6. 88? 11. 37 3. 45 9. 44 Radioquiet (? ) Close-by Thermal emission Absorption features Long periods 11
Population of close-by young NSs Ü Magnificent seven Ü Geminga and 3 EG J 1853+5918 Ü Four radio pulsars with thermal emission (B 0833 -45; B 0656+14; B 105552; B 1929+10) Ü Seven older radio pulsars, without detected thermal emission. Where are the rest? UNCATCHABLES 12
Population synthesis: ingredients Ü Birth rate of NSs Ü Initial spatial distribution Ü Spatial velocity (kick) Ü Mass spectrum Ü Thermal evolution Ü Interstellar absorption Task: To build an artificial model of a population of some astrophysical sources and to compare the results of calculations with observations. A brief review on population synthesis in astrophysics can be found in astro-ph/0411792 Ü Detector properties 13
Population synthesis – I. Gould Belt : 20 NS Myr-1 Gal. Disk (3 kpc) : 250 NS Myr-1 • Cooling curves by • Blaschke et al. • Mass spectrum ROSAT 18° Gould Belt Arzoumanian et al. 2002 © Bettina Posselt 14
Solar vicinity Ü Solar neighborhood is not a typical region of our Galaxy Ü Gould Belt Ü R=300 -500 pc Ü Age: 30 -50 Myrs Ü 20 -30 SN per Myr (Grenier 2000) Ü The Local Bubble Ü Up to six SN in a few Myrs 15
The Gould Belt Ü Ü Ü Poppel (1997) R=300 – 500 pc Age 30 -50 Myrs Center at 150 pc from the Sun Inclined respect to the galactic plane at 20 degrees 2/3 massive stars in 600 pc belong to the Belt 16
Initial spatial distribution A very simple model for PS-I: The Gould Belt as a flat inclined disc plus contribution from the galactic disc up to 3 kpc. 17
Mass spectrum of NSs Mass spectrum of local young NSs can be different from the general one (in the Galaxy) Ü Hipparcos data on near-by massive stars Ü Progenitor vs NS mass: Timmes et al. (1996); Woosley et al. (2002) Ü (masses of secondary objects in NS+NS) astro-ph/0305599 18
Progenitor mass vs. NS mass Woosley et al. 2002 19
Log of the number of sources brighter than the given flux Log N – Log S calculations -3/2 sphere: number ~ r 3 flux ~ r-2 -1 disc: number ~ r 2 flux ~ r-2 Log of flux (or number counts) 20
Some results of PS-I: Log N – Log S and spatial distribution Log N – Log S for closeby ROSAT NSs can be explained by standard cooling curves taking into account the Gould Belt. Log N – Log S can be used as an additional test of cooling curves More than ½ are in +/- 12 degrees from the galactic plane. 19% outside +/- 30 o 12% outside +/- 40 o (Popov et al. 2005 Ap&SS 299, 117) 21
Two tests Age – Temperature & Log N – Log S 22
Standard test: temperature vs. age Kaminker et al. (2001) 23
Uncertainties in temperature • Atmospheres (composition) • Magnetic field • Non-thermal contributions to the spectrum • Distance • Interstellar absorption • Temperature distribution (Pons et al. astro-ph/0107404) 24
Luminosity and age uncertainties Page, Geppert astro-ph/0508056 25
Log N – Log S as an additional test Ü Standard test: Age – Temperature Sensitive to ages <105 years Uncertain age and temperature Non-uniform sample Ü Log N – Log S Sensitive to ages >105 years (when applied to close-by NSs) Definite N (number) and S (flux) Uniform sample astro-ph/0411618 Ü Two test are perfect together!!! 26
List of models (Blaschke et al. 2004) Blaschke et al. used 16 sets of cooling curves. They were different in three main respects: 1. Absence or presence of pion condensate 2. Different gaps for superfluid protons Pions Crust Gaps Ü Model I. Yes C A Ü Model II. No D B Ü Model III. Yes C B Ü Model IV. No C B Ü Model V. Yes D B 27
Model I Ü Pions. Ü Gaps from Takatsuka & Tamagaki (2004) Ü Ts-Tin from Blaschke, Grigorian, Voskresenky Can reproduce observed Log N – Log S (2004) (astro-ph/0411618)28
Model II Ü No Pions Ü Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0. 1 Ü Ts-Tin from Tsuruta (1979) Cannot reproduce observed Log N – Log S 29
Model III Ü Pions Ü Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0. 1 Ü Ts-Tin from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S 30
Model IV Ü No Pions Ü Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0. 1 Ü Ts-Tin from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S 31
Model V Ü Pions Ü Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0. 1 Ü Ts-Tin from Tsuruta Cannot reproduce observed Log N – Log S (1979) 32
Model VI Ü No Pions Ü Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0. 1 Ü Ts-Tin from Yakovlev et al. (2004) Cannot reproduce observed Log N – Log S 33
Model VII Ü Pions Ü Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0. 1. 1 P proton gap 0 suppressed by 0. 5 Ü Ts-Tin from Blaschke, Grigorian, Cannot reproduce observed Log N – Log S Voskresenky (2004) 34
Model VIII Ü Pions Ü Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0. 1. 1 P proton gap 0 suppressed by 0. 2 and 1 P neutron gap 0 suppressed by 0. 5. Ü Ts-Tin from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S 35
Model IX Ü No Pions Ü Gaps from Takatsuka & Tamagaki (2004) Ü Ts-Tin from Blaschke, Grigorian, Can reproduce observed Log N – Log S Voskresenky (2004) 36
HOORAY!!!! Log N – Log S can select models!!!!! Only three (or even one!) passed the second test! ……. still………… is it possible just to update the temperature-age test? ? ? May be Log N – Log S is not necessary? Let’s try!!!! 37
Brightness constraint Ü Effects of the crust (envelope) Ü Fitting the crust it is possible to fulfill the T-t test … Ü …but not the second test: Log N – Log S !!! (H. Grigorian astro-ph/0507052) 38
Sensitivity of Log N – Log S Ü Log N – Log S is very sensitive to gaps Ü Log N – Log S is not sensitive to the crust if it is applied to relatively old objects (>104 -5 yrs) Ü Log N – Log S is not very sensitive to presence or absence of pions We conclude that the two test complement each other 39
Mass constraint • Mass spectrum has to be taken into account when discussing data on cooling • Rare masses should not be used to explain the cooling data • Most of data points on T-t plot should be explained by masses <1. 4 Msun In particular: • Vela and Geminga should not be very massive Phys. Rev. C (2006) nucl-th/0512098 (published as a JINR preprint) Cooling curves from Kaminker et al. 40
Another attempt to test a set of models. Hybrid stars. Astronomy meets QCD We studied several models for hybrid stars applying all possible tests: - T-t - Log N – Log S - Brightness constraint - Mass constraint We also tried to present examples when a model successfully passes the Log N – Log S test, but fails to pass the standard T-t test or fails to fulfill the mass constraint. nucl-th/0512098 41
Model I Brightness - OK T-t - OK Log N – Log S - poor Mass - NO 42
Model II Brightness - OK T-t - No Log N – Log S - OK Mass - NO 43
Model III Brightness - OK T-t - poor Log N – Log S - OK Mass - NO 44
Model IV Brightness - OK T-t - OK Log N – Log S - OK Mass - OK 45
Resume for Hy. Ss One model among four was able to pass all tests. 46
Population sythesis – II. recent improvements 1. Spatial distribution of progenitor stars a) Hipparcos stars up to 500 pc [Age: spectral type & cluster age (OB ass)] b) 49 OB associations: birth rate ~ Nstar c) Field stars in the disc up to 3 kpc Solid – new initial XYZ Dashed – Rbelt = 500 pc Dotted – Rbelt = 300 pc 47
Population sythesis – II. recent improvements 2. New cross sections & abundances and new mass spectrum Low mass stars are treated following astro-ph/0409422 Solid – new abundances, old mass Dotted – old abundances, old mass Dashed – new abundances, new mass 48
Population synthesis – II. recent improvements 3. Spatial distribution of ISM (NH) instead of : now : Dot-dashed and dot-dashed lines Represent two new models of the ISM distribution. 49
First results: new maps Popov et al. 2005 Count rate > 0. 05 cts/s Clearly several rich OB associations start to dominate in the spatial distribution b= +90° Cep? Per? Sco OB Ori b= -90° PSRs+ Geminga+ M 7 PSRs- 50
INSs and local surrounding Massive star population in the Solar vicinity (up to 2 kpc) is dominated by OB associations. Inside 300 -400 pc the Gould Belt is mostly important. De Zeeuw et al. 1999 Motch et al. 2006 51
50 000 tracks, new ISM model Candidates: Agueros Chieregato 52
Age and distance distributions 1 < cts/s < 10 0. 1 < cts/s < 1 0. 01 < cts/s < 0. 1 Age Distance 53
Where to search for more cowboys? We do not expect to find much more candidates at fluxes >0. 1 cts/s. Most of new candidates should be at fluxes 0. 01< f < 0. 1 cts/s. So, they are expected to be young NSs (<few 100 Mys) just outside the Belt. I. e. , they should be in nearby OB associations and clusters. Most probable candidates are Cyg OB 7, Cam OB 1, Cep OB 2 and Cep OB 3. Orion region can also be promising. Name l- l+ b- b+ Dist. , pc 130 90 L=110 10 Cyg OB 7 84 96 -5 9 600 -700 Cep OB 2 96 108 -1 12 700 0 Cep OB 3 108 113 1 7 700 -900 Cam OB 1 130 153 -3 8 800 -900 -10 (ads. gsfc. nasa. gov/mw/) 54
Resume New more detailed population synthesis model for local population of isolated NS is made Ü New results provide a hint to search for new coolers. Ü We predict that new objects can be identified at 0. 01<cts/s<0. 1 behind the Gould Belt in the directions of close-by rich OB associations, in particular Cep OB 2. Ü These objects are expected to be younger and hotter than the Magnificent seven. Ü 55
The Magnificent Seven Vs. Uncatchables Born in the Gould Belt. Bright. Middle-aged. Already observed. Born behind the Belt. Dimmer. Younger. Wanted. I thank all scientists with whom I collaborated during different stages of work on INSs and had fruitful discussions: D. Blaschke, M. Colpi, H. Grigorian, F. Haberl, V. Lipunov, R. Neuhauser, B. Posselt, M. Prokhorov, A. Treves, J. Trumper, …. 56
Main reviews Труды ГАИШ том 72 (2003) • NS basics: physics/0503245 • SGRs & AXPs: astro-ph/0406133 • Magnetars: -Observations AXPs SGR - Theory astro-ph/0610304 astro-ph/0608364 astro-ph/0504077 • Central compact X-ray sources in supernova remnants: astro-ph/0311526 • The Magnificent Seven: astro-ph/0609066 • RRATs: astro-ph/0608311 • Cooling of NSs: astro-ph/0508056 http: //xray. sai. msu. ru/~polar/sci_rev/ns. html 57
Radio detection Malofeev et al. (2005) reported detection of 1 RXS J 1308. 6+212708 (RBS 1223) in the low-frequency band (60 -110 MHz) with the radio telescope in Pushchino. In 2006 Malofeev et al. reported radio detection of another one. (back) 58
NS+NS binaries Pulsar mass Companion mass B 1913+16 1. 44 1. 39 B 2127+11 C 1. 35 1. 36 B 1534+12 1. 33 1. 35 J 0737 -3039 1. 34 1. 25 J 1756 -2251 1. 40 1. 18 (PSR+companion)/2 J 1518+4904 1. 35 J 1811 -1736 1. 30 J 1829+2456 1. 25 (David Nice, talk at Vancouver 2005) (Back) 59
- Slides: 59