New adventures of Uncatchables Sergei Popov SAI MSU (astro-ph/ and work in progress)

2 Plan of the talk  Intro. Pop. synthesis  Some old results  Two tests  New improvements 1. Initial distribution 2. Mass spectrum and abundances 3. ISM distribution  Maps  Age and distance distributions  Where to search?  Final conclusions

3 Good old classics The pulsar in the Crab nebula A binary system

4 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) ….

5 Main reviews NS basics: physics/ physics/ SGRs & AXPs: astro-ph/ Magnetars: -Observations AXPs astro-ph/ SGR astro-ph/ Theory astro-ph/ astro-ph/ Central compact X-ray sources in supernova remnants: astro-ph/ The Magnificent Seven: astro-ph/ RRATs: astro-ph/ Cooling of NSs: astro-ph/ astro-ph/ Труды ГАИШ том 72 (2003)

6 Isolated neutron stars population: in the Galaxy and at the backyard  INSs appear in many flavours Radio pulsars AXPs SGRs CCOs RINSs RRATs  Local population of young NSs is different (selection) Radio pulsars Geminga+ RINSs

7 Evolution of NSs. I.: temperature [Yakovlev et al. (1999) Physics Uspekhi] First papers on the thermal evolution appeared already in early 60s, i.e. before the discovery of radio pulsars.

8 Evolution of neutron stars. II.: rotation + magnetic field Ejector → Propeller → Accretor → Georotator See the book by Lipunov (1987, 1992) astro-ph/ – spin down 2 – passage through a molecular cloud 3 – magnetic field decay

9 Magnetorotational evolution of radio pulsars Spin-down. Rotational energy is released. The exact mechanism is still unknown.

10 Close-by radioquiet NSs  Discovery: Walter et al. (1996)  Proper motion and distance: Kaplan et al.  No pulsations  Thermal spectrum  Later on: six brothers RX J

11 Magnificent Seven NamePeriod, s RX RX RBS RBS ? RX RX RBS Radioquiet (?) Close-by Thermal emission Absorption features Long periods

12 Population of close-by young NSs  Magnificent seven  Geminga and 3EG J  Four radio pulsars with thermal emission (B ; B ; B ; B )  Seven older radio pulsars, without detected thermal emission. Where are the rest? UNCATCHABLES

13 Population synthesis: ingredients  Birth rate of NSs  Initial spatial distribution  Spatial velocity (kick)  Mass spectrum  Thermal evolution  Interstellar absorption  Detector properties A brief review on population synthesis in astrophysics can be found in astro-ph/ To build an artificial model of a population of some astrophysical sources and to compare the results of calculations with observations. Task:

14 Gould Belt : 20 NS Myr -1 Gal. Disk (3kpc) : 250 NS Myr -1 Arzoumanian et al ROSAT Cooling curves by Blaschke et al. Mass spectrum 18° Gould Belt Population synthesis – I. © Bettina Posselt

15 Solar vicinity  Solar neighborhood is not a typical region of our Galaxy  Gould Belt  R= pc  Age: Myrs  SN per Myr (Grenier 2000)  The Local Bubble  Up to six SN in a few Myrs

16 The Gould Belt  Poppel (1997)  R=300 – 500 pc  Age 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

17 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.

18 Mass spectrum of NSs  Mass spectrum of local young NSs can be different from the general one (in the Galaxy)  Hipparcos data on near-by massive stars  Progenitor vs NS mass: Timmes et al. (1996); Woosley et al. (2002) astro-ph/ (masses of secondary objects in NS+NS)

19 Woosley et al Progenitor mass vs. NS mass

20 Log N – Log S Log of flux (or number counts) Log of the number of sources brighter than the given flux -3/2 sphere: number ~ r 3 flux ~ r disc: number ~ r 2 flux ~ r -2 calculations

21 Some results of PS-I: Log N – Log S and spatial distribution (Popov et al Ap&SS 299, 117) More than ½ are in +/- 12 degrees from the galactic plane. 19% outside +/- 30 o 12% outside +/- 40 o Log N – Log S for close- by 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

22 Two tests Age – Temperature & Log N – Log S

23 Standard test: temperature vs. age Kaminker et al. (2001)

24 Uncertainties in temperature (Pons et al. astro-ph/ ) Atmospheres (composition) Magnetic field Non-thermal contributions to the spectrum Distance Interstellar absorption Temperature distribution

25 Luminosity and age uncertainties Page, Geppert astro-ph/

26 Log N – Log S as an additional test  Standard test: Age – Temperature Sensitive to ages <10 5 years Uncertain age and temperature Non-uniform sample  Log N – Log S Sensitive to ages >10 5 years (when applied to close-by NSs) Definite N (number) and S (flux) Uniform sample  Two test are perfect together!!! astro-ph/

27 List of models (Blaschke et al. 2004)  Model I. Yes C A  Model II. No D B  Model III. Yes C B  Model IV. No C B  Model V. Yes D B  Model VI. No E B  Model VII. Yes C B’  Model VIII.Yes C B’’  Model IX. No C A 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 and neutrons 3. Different T s -T in Pions Crust Gaps

28 Model I  Pions.  Gaps from Takatsuka & Tamagaki (2004)  T s -T in from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S (astro-ph/ )

29 Model II  No Pions  Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1  T s -T in from Tsuruta (1979) Cannot reproduce observed Log N – Log S

30 Model III  Pions  Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1  T s -T in from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S

31 Model IV  No Pions  Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1  T s -T in from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S

32 Model V  Pions  Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1  T s -T in from Tsuruta (1979) Cannot reproduce observed Log N – Log S

33 Model VI  No Pions  Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1  T s -T in from Yakovlev et al. (2004) Cannot reproduce observed Log N – Log S

34 Model VII  Pions  Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by P 0 proton gap suppressed by 0.5  T s -T in from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S

35 Model VIII  Pions  Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by P 0 proton gap suppressed by 0.2 and 1 P 0 neutron gap suppressed by 0.5.  T s -T in from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S

36 Model IX  No Pions  Gaps from Takatsuka & Tamagaki (2004)  T s -T in from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S

37 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!!!!

38 Brightness constraint  Effects of the crust (envelope)  Fitting the crust it is possible to fulfill the T-t test …  …but not the second test: Log N – Log S !!! (H. Grigorian astro-ph/ )

39 Sensitivity of Log N – Log S  Log N – Log S is very sensitive to gaps  Log N – Log S is not sensitive to the crust if it is applied to relatively old objects (> yrs)  Log N – Log S is not very sensitive to presence or absence of pions We conclude that the two test complement each other

40 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/ (published as a JINR preprint) Cooling curves from Kaminker et al.

41 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 nucl-th/ 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.

42 Model I Brightness - OK T-t - OK Log N – Log S - poor Mass - NO

43 Model II Brightness - OK T-t - No Log N – Log S - OK Mass - NO

44 Model III Brightness - OK T-t - poor Log N – Log S - OK Mass - NO

45 Model IV Brightness - OK T-t - OK Log N – Log S - OK Mass - OK

46 Resume for HySs One model among four was able to pass all tests.

47 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 ~ N star c) Field stars in the disc up to 3 kpc Population sythesis – II. recent improvements Solid – new initial XYZ Dashed – R belt = 500 pc Dotted – R belt = 300 pc

48 Population sythesis – II. recent improvements 2. New cross sections & abundances and new mass spectrum Solid – new abundances, old mass Dotted – old abundances, old mass Dashed – new abundances, new mass Low mass stars are treated following astro-ph/

49 3. Spatial distribution of ISM (N H ) instead of : now : Population synthesis – II. recent improvements Dot-dashed and dot-dot-dashed lines Represent two new models of the ISM distribution.

50 b= +90° b= -90° Popov et al Count rate > 0.05 cts/s Ori Sco OB Cep?Per? PSRs+ Geminga+ M7 PSRs- First results: new maps Clearly several rich OB associations start to dominate in the spatial distribution

51 INSs and local surrounding De Zeeuw et al Motch et al Massive star population in the Solar vicinity (up to 2 kpc) is dominated by OB associations. Inside pc the Gould Belt is mostly important.

tracks, new ISM model Agueros Chieregato Candidates:

53 Age and distance distributions Age 1 < cts/s < < cts/s < < cts/s < 0.1 Distance

54 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 OB7, Cam OB1, Cep OB2 and Cep OB3. Orion region can also be promising. Name l- l+ b- b+ Dist., pc Cyg OB Cep OB Cep OB Cam OB L= (ads.gsfc.nasa.gov/mw/)

55 Resume  New more detailed population synthesis model for local population of isolated NS is made  New results provide a hint to search for new coolers.  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 OB2.  These objects are expected to be younger and hotter than the Magnificent seven.

56 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, ….

57 Main reviews NS basics: physics/ physics/ SGRs & AXPs: astro-ph/ Magnetars: -Observations AXPs astro-ph/ SGR astro-ph/ Theory astro-ph/ astro-ph/ Central compact X-ray sources in supernova remnants: astro-ph/ The Magnificent Seven: astro-ph/ RRATs: astro-ph/ Cooling of NSs: astro-ph/ astro-ph/ Труды ГАИШ том 72 (2003)

58 Radio detection Malofeev et al. (2005) reported detection of 1RXS J (RBS 1223) in the low-frequency band ( MHz) with the radio telescope in Pushchino. In 2006 Malofeev et al. reported radio detection of another one. (back)

59 NS+NS binaries Pulsar Pulsar mass Companion mass B B C B J J (PSR+companion)/2 J J J (David Nice, talk at Vancouver 2005) (Back)Back