New adventures of UncatchablesNew adventures of Uncatchables

Sergei Popov, Bettina Posselt(astro-ph/0609275 and work in progress)

2

Plan of the talkPlan of the talk

Intro. Pop. synthesis Some old results New improvements1. Initial distribution2. Mass spectrum and abundances3. ISM distribution Maps Age and distance distributions Where to search? Final conclusions

3

Magnificent SevenMagnificent Seven

Name Period, sRX 1856 -RX 0720 8.39RBS 1223 10.31 RBS 1556 6.88?RX 0806 11.37RX 0420 3.45RBS 1774 9.44

Radioquiet (?)Close-byThermal emissionAbsorption featuresLong periods

4

Population of close-by young NSsPopulation of close-by young NSs

Magnificent seven Geminga and 3EG J1853+5918 Four radio pulsars with thermal emission

(B0833-45; B0656+14; B1055-52; B1929+10) Seven older radio pulsars, without detected

thermal emission.

Where are the rest?UNCATCHABLES

5

Population synthesis: ingredientsPopulation synthesis: ingredients

Birth rate of NSs Initial spatial distribution Spatial velocity (kick) Mass spectrum Thermal evolution Interstellar absorption Detector properties

A brief review on populationsynthesis in astrophysics canbe found in astro-ph/0411792

To build an artificial model

of a population of some astrophysical sources and

to compare the results ofcalculations with observations.

Task:

6

Gould Belt : 20 NS Myr-1

Gal. Disk (3kpc) : 250 NS Myr-1

Arzoumanian et al. 2002

ROSAT

• Cooling curves by• Blaschke et al. • Mass spectrum

18°Gould BeltGould Belt

Population synthesis – I. Population synthesis – I.

© Bettina Posselt

7

Solar vicinitySolar vicinity

Solar neighborhood is not a typical region of our Galaxy

Gould Belt R=300-500 pc Age: 30-50 Myrs 20-30 SN per Myr (Grenier 2000) The Local Bubble Up to six SN in a few Myrs

8

The Gould BeltThe Gould Belt

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

9

Initial spatial distributionInitial spatial distribution

A very simple model for PS-I: The Gould Belt as a flat inclined disc pluscontribution from the galactic disc up to 3 kpc.

10

Mass spectrum of NSsMass 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/0305599(masses of secondary objects in NS+NS)

11

Log N – Log S Log N – Log S

Log of flux (or number counts)

Lo

g o

f th

e n

um

ber

of

sou

rces

bri

gh

ter

than

th

e g

iven

flu

x

-3/2 sphere: number ~ r3

flux ~ r-2

-1 disc: number ~ r2

flux ~ r-2

calculations

12

Some results of PS-I:Log N – Log S and spatial distribution

Some results of PS-I:Log N – Log S and spatial distribution

(Popov et al. 2005 Ap&SS 299, 117)

More than ½ are in+/- 12 degrees from the galactic plane.19% outside +/- 30o

12% outside +/- 40o

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 ~

Nstar

c) Field stars in the disc up to 3 kpc

Population sythesis – II.recent improvementsPopulation sythesis – II.recent improvements

Solid – new initial XYZDashed – Rbelt = 500 pcDotted – Rbelt = 300 pc

14

Population sythesis – II.recent improvementsPopulation sythesis – II.recent improvements

2. New cross sections & abundances and new mass spectrum

Solid – new abundances, old massDotted – old abundances, old massDashed – new abundances, new mass

Low mass stars are treated followingastro-ph/0409422

15

3. Spatial distribution of ISM (NH)

instead of :

now :

Population synthesis – II.recent improvementsPopulation synthesis – II.recent improvements

Dot-dashed and dot-dot-dashed linesRepresent two new models of theISM distribution.

16

b= +90°

b= -90°

Popov et al. 2005

Count rate > 0.05 cts/s

OriSco OB

Cep?Per?

PSRs+

Geminga+

M7

PSRs-

First results: new mapsFirst results: new maps

Clearly several richOB associations startto dominate in thespatial distribution

17

INSs and local surroundingINSs and local surrounding

De Zeeuw et al. 1999 Motch et al. 2006

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.

18

50 000 tracks, new ISM model50 000 tracks, new ISM model

AguerosChieregato

Candidates:

19

Age and distance distributionsAge and distance distributions

Age

1 < cts/s < 10 0.1 < cts/s < 1 0.01 < cts/s < 0.1

Distance

20

Where to search for more cowboys?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 OB7     84      96     -5     9       600-700

Cep OB2     96     108    -1   12       700

Cep OB3    108    113     1     7       700-900

Cam OB1   130    153    -3     8       800-900

0

10

-10

L=110 90130

(ads.gsfc.nasa.gov/mw/)

21

Resume 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. UncatchablesThe 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 detectionRadio detection

Malofeev et al. (2005) reported detection of 1RXS J1308.6+212708 (RBS 1223) in the low-frequency band (60-110 MHz) with the radio telescope in Pushchino.

In 2006 Malofeev et al. reported radio detectionof another one.

(back)

24

NS+NS binariesNS+NS binaries

Pulsar Pulsar mass Companion mass

B1913+16 1.44 1.39B2127+11C 1.35 1.36B1534+12 1.33 1.35J0737-3039 1.34 1.25J1756-2251 1.40 1.18

(PSR+companion)/2

J1518+4904 1.35J1811-1736 1.30J1829+2456 1.25

(David Nice, talk at Vancouver 2005)

(Back)