Fermi Gamma-ray Haze via Dark Matter and Millisecond Pulsars Dmitry - - PowerPoint PPT Presentation

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Aug 13, 2023 219 likes •359 views

Fermi Gamma-ray Haze via Dark Matter and Millisecond Pulsars Dmitry Malyshev, Ilias Cholis, Joseph Gelfand CCPP, NYU arxiv: 1002.0587 Gamma-ray haze via DM and MSPs Gamma-ray haze data Dobler et al. arxiv:0910.4583 This is the gamma-ray

SLIDE 1

Fermi Gamma-ray Haze via Dark Matter and Millisecond Pulsars

Dmitry Malyshev, Ilias Cholis, Joseph Gelfand CCPP, NYU

arxiv:1002.0587

SLIDE 2

Gamma-ray haze via DM and MSPs

Gamma-ray haze data

This is the gamma-ray overdensity that remains after subtracting these templates from the Fermi data

Dobler et al. arxiv:0910.4583

SLIDE 3

Gamma-ray haze via DM and MSPs

Possibilities to consider:

1. Dark Matter annihilation
2. IA supernovae electrons
3. Millisecond pulsars pulsed gamma-rays and e+e-

SLIDE 4

Gamma-ray haze via DM and MSPs

Compare the luminosities in the Milky Way halo

1. Dark Matter
2. IA supernovae
3. Millisecond pulsars

∼ 1038erg/s

Gamma-ray haze:

SLIDE 5

Gamma-ray haze via DM and MSPs

Compare the luminosities in the Milky Way halo

1. Dark Matter:

freeze out cross section mass 300 GeV Einasto profile local DM density

σv0 = 3.0 × 10−26cm3s−1 ρDM = 0.4 GeVcm−3 ∼ 1038erg/s

Gamma-ray haze:

We need either large boost factors

r prompt gamma-ray emission

∼ 2 × 1037erg/s

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Gamma-ray haze via DM and MSPs

1. Dark Matter:
2. IA supernovae:

∼ 1038erg/s

Gamma-ray haze:

Compare the luminosities in the Milky Way halo

Based on 1A SNe rate in the halo (Sullivan et al. 2006) and average SNe output in electrons necessary to account for high energy cosmic rays (Kobayashi et al. 2004)

5 × 10−14 yr−1 M −1

⊙

1048erg ∼ 2 × 1037erg/s < 1037erg/s

SLIDE 7

Gamma-ray haze via DM and MSPs

1. Dark Matter:
2. IA supernovae:
3. Millisecond pulsars:

∼ 1038erg/s

Gamma-ray haze:

Compare the luminosities in the Milky Way halo

For a population of 50 000 pulsars in the Milky Way halo with average spin-down luminosity for 8 MSPs observed by Fermi

(Abdo et al. 2009)

2 × 1034erg/s ∼ 2 × 1037erg/s < 1037erg/s < 1039erg/s

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Gamma-ray haze via DM and MSPs

Pulsed gamma-rays from 47 Tuc MSPs are similar to low energy part in the gamma-ray haze spectrum. Thus we can expect that the low energy part can be explained by a population of MSPs in the Milky Way halo. The high energy part of the gamma-haze spectrum is more difficult to explain.

47 Tuc MSPs Milky Way halo MSPs ? DM ?

Dobler et al. 2009

Abdo et al. 2009

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Gamma-ray haze via DM and MSPs

1e-07 1e-06 0.1 1 10 100 1000

E2 Intensity (GeV cm-2 sec-1 sr-1) Energy (GeV) M!=300 GeV

Fermi Haze Template (|l| " 15, -30 " b " -10) Total DM W+W-, Prompt # DM W+W-, ICS off ISRF×10 MSPs pulsed #, P#=5.6×1037erg s-1 MSPs ICS off ISRF, Pe±=2.7×1038erg s-1

Pulsed gammas MSP e+e- ICS DM prompt gammas DM e+e- ICS x10

1 2 3 4 5 6 7 5 10 15 20 25 30 35

Intensity (10-20 erg/sec/Hz/cm2/sr) Latitudinal Radial Distance from GC (degrees) v = 23 GHz

Total DM W+W-, M!=300 GeV Milky Way Halo MSPs constant Haze Data

Both gamma-ray haze and WMAP haze are OK

In this model we need 30 000 MSPs in Milky Way halo with average spin-down energy conversion efficiencies

ηγ = 0.1 ηe± = 0.5

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Gamma-ray haze via DM and MSPs

Pulsed gammas DM prompt gammas DM e+e- ICS x10

1e-07 1e-06 0.1 1 10 100 1000

E2 Intensity (GeV cm-2 sec-1 sr-1) Energy (GeV) M!=300 GeV, B.F.=3

Fermi Haze Template (|l| " 15, -30 " b " -10) Total DM W+W-, Prompt # DM W+W-, ICS off ISRF×10 MSPs pulsed #, P#=1.3×1038erg s-1

MSPs pulsed gammas and DM to W+W- prompt gammas

1 2 3 4 5 6 7 5 10 15 20 25 30 35

Intensity (10-20 erg/sec/Hz/cm2/sr) Latitudinal Radial Distance from GC (degrees) v = 23 GHz

Total DM W+W-, M!=300 GeV, B.F.=3 constant Haze Data

Gamma-ray haze: OK with DM BF = 3 WMAP haze: No Here we need 60 000 MSPs in Milky Way halo with ηγ = 0.1

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Gamma-ray haze via DM and MSPs

Pulsed gammas DM FSR x100 DM e+e- ICS

MSPs pulsed gammas and DM e+e- annihilation

Gamma-ray haze: OK with DM BF = 100 WMAP haze: OK

1e-07 1e-06 0.1 1 10 100 1000

E2 Intensity (GeV cm-2 sec-1 sr-1) Energy (GeV) M!=1.2 TeV, B.F.=100

Fermi Haze Template (|l| " 15, -30 " b " -10) Total XDM e±, ICS off ISRF XDM e±, FSR×100 MSPs pulsed #, P#=3.4×1037erg s-1

1 2 3 4 5 6 7 5 10 15 20 25 30 35

Intensity (10-20 erg/sec/Hz/cm2/sr) Latitudinal Radial Distance from GC (degrees) v = 23 GHz

Total XDM e±, M!=1.2 TeV, B.F.=100 constant Haze Data

In this case we need 20 000 MSPs in Milky Way halo with ηγ = 0.1

SLIDE 12

Gamma-ray haze via DM and MSPs

Conclusions

1. In DM models with one type of DM particles we need

an astrophysical source of gamma-rays in the Milky Way halo

2. Millisecond pulsars is the most plausible such source
3. We need about 20 000 - 60 000 MSPs in the Milky Way stellar

halo.

4. To fit the WMAP haze we need either
leptonically annihilating DM with BF ~ 100 or
significant e+e- emission from MSPs (about 50% of spin-down)