New adventures of Uncatchables Sergei Popov, Bettina Posselt (astro-ph/ and work in progress)

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

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

4 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

5 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:

6 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

7 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

8 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

9 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.

10 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)

11 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

12 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

13 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

14 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/

15 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.

16 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

17 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:

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

20 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/)

21 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.

22 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, M. Prokhorov, A. Treves, J. Trumper, ….

23 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)

24 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