Some results about Fermi observation of M31

Residual maps of different energy bands

2 year statistc by Abdo et al. M31~ 2401ES 0037+405 ~8

5 year counts ofM31~ 629

Counts statistic roughly

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

1 4

2 3

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

Disc model

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

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 workTS Flux ph cm−2

s−1Index

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

200mev -1gev

Ps 14.6 3.1±0.3e-9 3

Disc 32.4 4.5±0.8e-9 2.2

1-20gevPs 38.2 4.9±1e-10 3.2

disc 23.8 6.3±1e-10 2.6

200mev-20gev

ps 51.8 4.3±1e-9 2.6

disc 59.4 5.8±1e-9 2.5

200mev-300gev

ps 60.3 5.1±1e-9 2.7

disc 58.3 6.2±1e-9 2.6

PS4 calculation—flux and size

dm31 = 780kpc Lbubble = 4*10^37 erg/s

Flux= L/4πd^2 = 5*10^-13 erg/s/cm^-2Flux of PS4 ~ 7*10^-14 erg/s/cm^-2

Bubble size ±50°d=9.6kpc ~11.4kpcPs4 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 modelThe 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 200mev-300gev, 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 workK-band modelTwo 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