Transcript Close-by young isolated neutron stars (and black holes)

New adventures of Uncatchables
Sergei Popov, Bettina Posselt
(astro-ph/0609275 and work in progress)
Abstract
We present preliminary results of a new
model of population synthesis of closeby young isolated neutron stars.
Population of
close-by young NSs
Magnificent
Geminga
seven
and 3EG J1853+5918
Four
In comparison with the previous models
we include detailed initial distribution of
NS progenitors and detailed distribution
of the ISM. In addition we tried to vary
NS mass spectrum and modified the
procedure of calculating absorbed
ROSAT flux.
The results suggest that new isolated
cooling neutron stars should we
searched at count rates 0.01<cts/s<0.1
in the direction of rich OB associations
behind the Gould Belt. These sources
are expected to be younger, and so
hotter, than the Magnificent Seven.
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
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Some old results of Pop. Synthesis-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 +/- 30o
12% outside +/- 40o
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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
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Population sythesis – II.
recent improvements
2. New cross sections & abundances
and new mass spectrum
Low mass stars masses are
treated following
astro-ph/0409422
Solid – new abundances, old mass
Dotted – old abundances, old mass
Dashed – new abundances, new mass
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Population synthesis – II.
recent improvements
3. Spatial distribution of ISM (NH)
instead of :
now :
Dot-dashed and dot-dot-dashed lines
represent two new models of the
ISM distribution.
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First new 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+
M7
PSRs-
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First new results:
50 000 tracks, new ISM model
Candidates:
Agueros
Chieregato
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First new results:
Age and distance distributions
1 < cts/s < 10
0.1 < cts/s < 1
0.01 < cts/s < 0.1
Age
Distance
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Where to search for more cavaliers?
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+
Cyg OB7
84
96
-5
9
Cep OB2
96
108
-1 12
700
Cep OB3
108
113
1
700-900
7
Dist., pc 130
90
L=110
10
600-700
0
-10
Cam OB1 130
153
-3
8
800-900
(ads.gsfc.nasa.gov/mw/)
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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. Task for eRosita?
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The Magnificent Seven Vs. Uncatchables
Born in the Gould Belt.
Bright. Middle-aged.
Already detected.
Born behind the Belt.
Dimmer. Younger.
Wanted.
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