Solar vicinity, close-by young isolated NSs, and tests of cooling curves
Sergei Popov
(Sternberg Astronomical Institute)
Co-authors: H.Grigorian, R. Turolla, D. Blaschke
ECT*, Trento, September 14, 2005

Plan of the talk









Intro. Close-by NSs
Age-Distance diagram
Solar vicinity. Stars
Spatial distribution
Mass spectrum
Two tests of cooling
Brightness constraint
Sensitivity of two tests
Final conclusions
2

Isolated neutron stars population: in the Galaxy and at the backyard
 INSs appear in many flavours
 Radio pulsars
 AXPs
 SGRs
 CCOs
 RINSs
Note a recent discovery by Lyne et al. (submited to Nature, see later)
 Local population of young NSs is different (selection)
 Radio pulsars
 Geminga+
 RINSs
3

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 J1856.5-3754
4

Magnificent Seven
Name
RX 1856
RX 0720
RBS 1223
RBS 1556
RX 0806
RX 0420
RBS 1774
Period, s
-
8.39
10.31
-
11.37
3.45
9.44
Radioquiet (?)
Close-by
Thermal emission
Long periods
5

Population 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.
6

Age-distance diagram
A toy-model: a local sphere (R=300 pc) and a flat disk.
Rate of NS formation in the sphere is
235 Myr -1 kpc -3
(26-27 NS in Myr in the whole sphere).
Rate in the disc is
10 Myr -1 kpc -2
(280 NS in Myr up to
3 kpc).
7
(astro-ph/0407370)

More realistic age-dist. diagram
Initial distribution from Popov et al. 2005.
Spatial evolution is not followed.
For the line of “visibility”
(solid line in the middle)
I assume the limiting flux 10 -12 erg s -1 cm -2 and masses are <1.35
(Yakovlev et al. curves).
8

Realistic age-distance diagram
Realistic initial distribution.
Spatial evolution is taken into account.
The line of “visibility” is drawn as the dotted line.
Five curves correspond to
1, 4 , 13, 20 and 100 NSs.
9

Solar 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
10

The 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
11

Distribution of open clusters
(Piskunov et al. astro-ph/0508575)
12

Surface density of open clusters
(Piskunov et al.)
13

Spatial distribution of close-by open clusters in 3D
Grey contours show projected density distribution of young
(log T<7.9) clusters.
14
(Piskunov et al.)

Clusters and absorption
Triangles –
Gould Belt clusters.
(Piskunov et al.)
15

Spatial distribution
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)
Lyne et al. reported transient dim radio sources with
possible periods
about seconds in the galactic plane discovered in the Parkes survey
(talk by A. Lyne in Amsterdam, august 2005; subm. to Nature).
Shall we expect also Lyne’s objects from the Belt????
YES!!! And they even have to be brighter (as they are closer).
The problem – low dispersion.
16

Mass spectrum of NSs

 Hipparcos data on near-by massive stars

Mass spectrum of local young NSs can be different from the general one (in the
Galaxy)
Progenitor vs NS mass:
Timmes et al. (1996);
Woosley et al. (2002)
(masses of secondary objects in NS+NS)
astro-ph/0305599
17

Two tests
Age – Temperature
&
Log N – Log S
18

Standard test: temperature vs. age
Kaminker et al. (2001)
19

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

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/0411618
21

List of models (Blaschke et al. 2004)
Blaschke et al. used 16 sets of cooling curves.
They were different in three main respects:
1.
2.
3.
Absence or presence of pion condensate
Different gaps for superfluid protons and neutrons
Different T s
-T in
Pions Crust Gaps









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
22

Model I


Pions.
Gaps from Takatsuka & Tamagaki
(2004)
 T s
-T in from Blaschke, Grigorian,
Voskresenky (2004)
Can reproduce observed Log N – Log S
23

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
24

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
25

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
26

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
27

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
28

Model VII


Pions
Gaps from Yakovlev et al. (2004), 3 P
2 neutron gap suppressed by 0.1.
1 P
0 proton gap suppressed by 0.5
 T s
-T in from Blaschke,
Grigorian, Voskresenky
(2004)
Cannot reproduce observed Log N – Log S
29

Model VIII


Pions
Gaps from Yakovlev et al.
(2004), 3 P
2 neutron gap suppressed by 0.1. 1 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
30

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
31

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!!!!
32

Brightness constraint
 Effects of the crust
(envelope)
 Fitting the crust it is possible to fulfill the
Tt test …
 …but not the second test:
Log N – Log S !!!
(H. Grigorian astro-ph/0507052)
33

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 (>10 4-5 yrs)
Log N – Log S is not very sensitive to presence or absence of pions
Model I (YCA) Model II (NDB) Model III (YCB)
Model IV (NCB) Model V (YDB) Model VI (NEB)
Model
VII(YCB’) Model VIII (YCB’’) Model IX (NCA)
We conclude that the two test complement each other
34

THAT’S ALL. THANK YOU!
35

Resume
 We live in a very interesting region of the Milky
Way!
 Log N – Log S test can include NSs with unknown ages, so additional sources
(like the Magnificent Seven) can be used to test cooling curves
 Two tests (LogN –LogS and Age-Temperature) are perfect together.
36

Radio 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.
(back)
37

Evolution of NS: spin + magnetic field
Ejector → Propeller → Accretor → Georotator
1 – spin-down
2 – passage through a molecular cloud
3 – magnetic field decay
Lipunov (1992) astro-ph/0101031
38

Model I


Pions.
Gaps from Takatsuka & Tamagaki
(2004)
 T s
-T in from Blaschke, Grigorian,
Voskresenky (2004)
Can reproduce observed Log N – Log S
(back)
39

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
(back)
40

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
(back)
41

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
(back)
42

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
(back)
43

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
(back)
44

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
(back)
45

Model VII


Pions
Gaps from Yakovlev et al. (2004), 3 P
2 neutron gap suppressed by 0.1.
1 P
0 proton gap suppressed by 0.5
 T s
-T in from Blaschke,
Grigorian, Voskresenky
(2004)
Cannot reproduce observed Log N – Log S
(back)
46

Model VIII


Pions
Gaps from Yakovlev et al.
(2004), 3 P
2 neutron gap suppressed by 0.1. 1 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
(back)
47

NS+NS binaries
Pulsar Pulsar mass Companion mass
B1913+16 1.44 1.39
B2127+11C 1.35 1.36
B1534+12 1.33 1.35
J0737-3039 1.34 1.25
J1756-2251 1.40 1.18
(PSR+companion)/2
J1518+4904 1.35
J1811-1736 1.30
J1829+2456 1.25
(David Nice, talk at Vancouver)
48
(
Back )

P-Pdot for new transient sources
Lyne et al. 2005
Submitted to Nature
(I’m thankful to
Prof. Lyne for giving me an opportunity to have a picture in advance)
Estimates show that there should be about
400 000 sources of this type in the Galaxy
(back)
49