one coin, two sides: the microwave and gamma-ray haze Greg Dobler - - PowerPoint PPT Presentation

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one coin, two sides: the microwave and gamma-ray haze Greg Dobler - - PowerPoint PPT Presentation

Dec 29, 2022 147 likes •537 views

one coin, two sides: the microwave and gamma-ray haze Greg Dobler (KITP/UCSB) one coin, two sides: the microwave and gamma-ray haze Greg Dobler (KITP/UCSB) the Fermi haze from DM annihilation: halo shapes and anisotropic diffusion Greg Dobler

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Greg Dobler (KITP/UCSB)

  • ne coin, two sides:

the microwave and gamma-ray haze

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Greg Dobler (KITP/UCSB)

  • ne coin, two sides:

the microwave and gamma-ray haze

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Greg Dobler (KITP/UCSB)

the Fermi haze from DM annihilation:

halo shapes and anisotropic diffusion

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Greg Dobler (KITP/UCSB)

Ilias Cholis (NYU) Neal Weiner (NYU)

the Fermi haze from DM annihilation:

halo shapes and anisotropic diffusion

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Greg Dobler (KITP/UCSB)

Ilias Cholis (NYU) Neal Weiner (NYU) Doug Finkbeiner (Harvard/CfA) Tracy Slatyer (Harvard/CfA) Tongyan Lin (Harvard/CfA)

the Fermi haze from DM annihilation:

halo shapes and anisotropic diffusion

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the Fermi haze

Fermi 2-5 GeV

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the Fermi haze

Fermi 2-5 GeV

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the Fermi haze

Fermi 2-5 GeV

two robust features:

. elongated in b with an axis ratio ~1.7 . spectrum is harder than elsewhere

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the Fermi haze (spectrum)

Fermi 2-5 GeV

spectrum is consistent with IC emission from a hard population of electrons

. amplitude/shape can be fit model-independently . consistent with leptonic DM annihilations

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the Fermi haze (spectrum)

Lin, Finkbeiner, & Dobler (2010)

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the Fermi haze (morphology)

Fermi 2-5 GeV

morphology... much more difficult:

. north/south “edge”? . what happens towards the center?

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haze residuals

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haze residuals

SFD Uniform Haslam Bubbles 0.5<E<1.0 GeV Uniform GALPROP (modified)

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haze residuals

SFD Uniform Haslam Bubbles 0.5<E<1.0 GeV Uniform GALPROP (modified)

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hourglass or oval?

line of sight gas density issues?

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hourglass or oval?

line of sight gas density issues?

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hourglass or oval?

line of sight gas density issues?

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hourglass or oval?

line of sight gas density issues?

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hourglass or oval?

line of sight gas density issues?

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Fermi haze morphology

  • w x
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Fermi haze morphology

  • w x
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Fermi haze morphology

very little “pinching”, but… slightly under- subtracted disk, noisier significant “pinching”, but… over-subtracted disk, less noisy

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Fermi haze morphology

let’s run with this one for now...

does an IC signal from DM annihilation electrons produce this shape???

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dark matter IC morphology

not for “typical” diffusion parameters, but...

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dark matter IC morphology

not for “typical” diffusion parameters, but...

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dark matter IC morphology

not for “typical” diffusion parameters, but...

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dark matter IC morphology

not for “typical” diffusion parameters, but... for anisotropic diffusion yes!!!

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anisotropic diffusion via ordered fields

electrons travel along ordered magnetic fields, we motivate anisotropic diffusion by including both turbulent and ordered components: diffusion coefficients along r and z are related to the ratio of ordered vs turbulent field

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three IC components

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three IC components

starlight IC infrared IC CMB IC + +

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three IC components

starlight IC infrared IC CMB IC + +

template fitting may “soak up” star and IR components leaving a more hourglass-like shape...

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Fermi haze residuals

Cholis, Dobler, & Weiner, in prep

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Fermi haze residuals

Cholis, Dobler, & Weiner, in prep

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Fermi haze residuals

Cholis, Dobler, & Weiner, in prep

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Fermi haze residuals

Cholis, Dobler, & Weiner, in prep

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Fermi haze spectrum

Cholis, Dobler, & Weiner, in prep

  • anisotropic diffusion
  • prolate Einasto, q=2/3
  • Mχ=1.2 TeV, XDM, χχ->e+e-
  • Sommerfeld boost = 70
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conclusions

  • the Fermi haze has two unique features:

. morphology (elongated in b with respect to l) . spectrum (harder than elsewhere in the Galaxy)

  • particle DM models can reproduce the spectrum of IC

emission and amplitude with cross-section enhancement

  • morphology is more subtle but doable

. a spherical DM halo with isotropic diffusion provides a poor fit . a prolate DM halo with anisotropic diffusion provides a reasonable fit

  • outstanding issues:

. upper/lower “edge” (the most tricky part!!!) . morphology (bubbles? oval? templates to use?) . synchrotron polarization

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