Some results about Fermi
observation of M31
Residual maps of different energy
bands
2 year statistc by Abdo et al.
M31~ 240
1ES 0037+405 ~8
5 year counts of
M31~ 629
Counts statistic roughly
1
4
2
3
200mev-1gev
1-20gev
20-300gev
ps1
29.4
29.6
3.6
ps2
-10.8
0.3
4
ps3
7？
8
3.6
ps4
-0.7
29.5
3.7
20-300 GeV5
Ps model
TS
flux
index
ps1
36.1
2.7e-11 ±1.1e-12
2.5
ps2
9.2
2.2e-11±1.2e-12
1
ps3
28.1
3e-11±1.3e-12
0.7
ps4
7.8
1.6e-11±1.6e-12
5
M31
-6.5e-9 ~0
2.8e-20±2.9e-16
5
ps1
36.5
2.7e-11±4.5e-12
2.5
ps2
9.8
2.3e-11±4.7e-12
1
ps3
28.7
3e-11±5.1e-12
0.7
ps4
8.1
1.6e-11±1.5e-12
5
M31
-9.2e-9 ~0
2.6e-20±2.8e-16
5
Disc model
200MeV-300 GeV
Ps model
TS
flux
index
TS
flux
index
ps1
63.5
1.1e-9 ±5e-10
1.9
63.2
1.1e-9±4.9e-10
2
ps2
15
9.7e-11±8.5e-11
1.2
15
9.6e-11±8.4e-10
1.3
ps3
36
3e-10±2.3e-10
1.4
-------
---------------------- ----
ps4
7.8
4.7e-10±4.7e-10
1.9
8.2
4.9e-10±4.7e-10
1.8
M31
60.3
5.1e-9±9.7e-10
2.7
66.5
5.2e-9±9.5e-10
2.6
Disc model
ps1
64.5
1.3e-9±5.4e-10
1.9
64.9
1.3e-9±5.5e-10
1.9
ps2
15.1
1e-10±9e-11
1.2
15
9.8e-11±8.7e-10
1.2
ps3
28.4
1.3e-10±1e-10
1.2
--------
---------------------- ----
ps4
6
2.4e-10±2.7e-10
1.7
5.6
2.2e-10±2.7e-10
1.7
M31
58.3
6.2e-9±1.1e-9
2.6
78.1
5.5e-9±9.6e-10
2.3
1-20 GeV
Ps model
TS
flux
index
TS
flux
index
ps1
22.4
1.9e-10 ±7e-11
1.7
22.3
1.9e-10±7.1e-11
1.7
ps2
3.7
5.3e-11±4.2e-11
1.5
3.7
5.3e-11±4.2e-11
1.5
ps3
7.6
8.6e-11±6.4e-11
1.4
---------
--------------------
-------
ps4
5.3
8.5e-11±7.7e-11
1.8
5.3
8.9e-11±7.8e-11
1.8
M31
38.2
4.7e-10±9.9e-11
3.3
41.7
4.9e-10±9.7e-10
3.2
Disc model
ps1
21.8
1.8e-10±6.7e-11
1.7
22.4
1.9e-10±7e-11
1.7
ps2
3.5
5.2e-11±4.2e-11
1.5
3.8
5.4e-11±4.3e-11
1.5
ps3
4.7
4.5e-11±4.3e-11
0.86
--------
-------------------
-----
ps4
4.3
5.1e-11±6.1e-11
1.4
4.3
5.3e-11±6.6e-11
1.2
M31
23.8
5.8e-10±1.4e-10
3.2
30
6.3e-10±1.4e-10
2.6
200MeV-1 GeV
Ps model
TS
flux
index
TS
flux
index
ps1
15.8
1e-9±1.7e-11
0.23
14.8
9.1e-10±1.3e-10
0.07
ps2
-8.39e-7
8.1e-11±2.1e-11
0.004
------
---------------------
-----
ps3
7.6
9.9e-10±1.6e-10
1
------
---------------------
-----
ps4
0.8
2.9e-10±1.4e-10
0.8
-------
---------------------- ------
M31
14.6
3.1e-9±3e-10
3.3
27.4
3.9e-9±3.5e-10
Disc model
ps1
15.2
1e-9±4.8e-10
0.5
15
1.1e-9±6.9e-10
0.4
ps2
-4.4e-7
1.2e-15±1.2e-11
0.2
------
------------------
----
ps3
0.5
1.6e-10±2.7e-10
9.8e-11
------
------------------
----
ps4
7.84
1.9e-15±4.9e-12
0.02
--------
---------------------
-----
M31
32.4
4.5e-9±7.6e-10
2.2
38.3
4.6e-9±1.1e-9
2
200MeV-20 GeV
Ps model
TS
flux
index
TS
flux
index
ps1
30.6
1.4e-9 ±6.3e-10
2
30.1
1.3e-9±6.1e-10
2
ps2
3.3
8.5e-11±1.2e-10
1.3
3.2
8.4e-11±1.2e-10
1.3
ps3
10.8
7.6e-10±8.3e-10
2
-------
---------------------- ----
ps4
4.4
2.4e-10±5.1e-10
1.7
4.7
3.3e-10±5.9e-10
1.8
M31
51.8
4.3e-9±1.1e-9
2.6
65.9
4.8e-9±9.5e-10
2.6
Disc model
ps1
31.5
1.5e-9±6.5e-10
2.1
31.4
1.5e-9±6.6e-10
2
ps2
3.3
9e-11±1.3e-10
1.3
3.3
8.9e-11±1.3e-10
1.3
ps3
3.3
7.3e-11±1.5e-10
1
--------
---------------------- ----
ps4
3.5
4.3e-11±1.1e-10
0.9
3.5
3.7e-11±9.4e-11
1.8
M31
59.4
5.8e-9±1e-9
2.5
66.4
5.7e-9±1e-9
2.4
Compare to formal work
TS
Flux ph cm−2 s−1 Index
Abdo et al.
200mev-20gev
Ps
25.5
-------------
2.5
disc
28.8
11 ± 4.7e-9
(>100mev)
2.1
Yuan et al.
200mev-300gev
Ps
50.4
-------------
2.4
Disc
54
-------------
2.1
Ps
14.6
3.1±0.3e-9
3
Disc
32.4
4.5±0.8e-9
2.2
Ps
38.2
4.9±1e-10
3.2
disc
23.8
6.3±1e-10
2.6
ps
51.8
4.3±1e-9
2.6
disc
59.4
5.8±1e-9
2.5
ps
60.3
5.1±1e-9
2.7
disc
58.3
6.2±1e-9
2.6
200mev -1gev
1-20gev
200mev-20gev
200mev-300gev
PS4 calculation—flux and size



dm31 = 780kpc
Lbubble = 4*10^37 erg/s
Flux= L/4πd^2 = 5*10^-13 erg/s/cm^-2
Flux of PS4 ~ 7*10^-14 erg/s/cm^-2
Bubble size ±50°d=9.6kpc ~11.4kpc
Ps4 size ~7.48kpc
Fermi bubble emission at 1-50 gev with
index 2 harder than π0 decay. While ps4
emission mainly at >1 gev, with index 1.8
(M31 ps model).
Near infrared K-band model

The distribution of LMXBs( MSPs) is consistent
with the distribution of the K-band light, and show
dense concentrate with 1 arcminute in M31 bulge.
(R. Voss et al. 2007, N. Kevork et al. 2012)
200mev-20gev
TS
flux
index
K-band model 75.9
5.5±0.9e-9
2.5
Ir_model
66.4
5.7±1e-9
2.4
Ps model
65.9
4.8±0.9e-9
2.6
Summury
M31 gamma ray emission mainly at energy <20gev.
There hardly have photon >20gev. While total flux
mainly contribute to <1gev. Flux1-20gev is about 1/8
flux200mev-1gev .
 PS3 corresponding to BL Lac object 1ES
0037+405(Abdo et al.), contribute gamma ray
photon mainly above 1gev, which affect likelihood
analysis results of M31, lead to a deflection of disc
model at total band.
We find that in 200mev-1gev band, emission like a
disc better(4.2σ), while in 1gev-20gev, emission is
more concentrate, more like a pointsource（3.7
σ ).


PS4 near center of M31 seem to elongate
with minor axis, emission mainly on energy
band >1gev. Which remind us about Fermi
bubble of our galaxy.
The luminosity and size of ps4 are
comparable with values if Fermi bubble in
M31 distance.
However it is one side structure, different
from Fermi bubble.
We have to think more about the origin of
this structure.

PS1 very close to north point of major
axis of M31, emission from 200mev300gev, powerlaw index ~1.9, luminosity is
1/5 of M31 in total bands. We consider it
a very significant source. While we also
curious about its origin.
Further to work
K-band model
 Two component

问题汇总

低能角分辨率不高，有没有使点源看起
来像盘。
在likelihood analysis中点源和盘模型还
是有区别的。如果做出来是盘模型ts值
更高只能说明更像盘模型。即使在低能
段，盘和点源的辐射也是有区别的。

分能段做会导致点源ts值和index不符合
真实。
这里实际上主要是普模型的影响。Ts
值只是反应在这个能段下在这个谱模型
和空间模型下，获得光子的概率。如果
普模型和空间模型定的准确，那么该源
在这个能段的ts值也就可以知道了。
关键在于如何给出普模型。这涉及到
fermi如何拟合源的过程。假如一个源
在