Radio continuum spectra of galaxies Uli Klein (Univ. Bonn) Ute - - PowerPoint PPT Presentation

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Radio continuum spectra of galaxies Uli Klein (Univ. Bonn) Ute - - PowerPoint PPT Presentation

Feb 19, 2024 277 likes •480 views

Radio continuum spectra of galaxies Uli Klein (Univ. Bonn) Ute Lisenfeld (Univ. de Granada) Simon Verley (Univ. de Granada) Bonn, Feb. 2018 1 star-forming galaxies: FIR, free-free radiation star-formation Lyc photons H , H ,

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Radio continuum spectra of galaxies

Uli Klein (Univ. Bonn) Ute Lisenfeld (Univ. de Granada) Simon Verley (Univ. de Granada)

Bonn, Feb. 2018 1

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star-forming galaxies:

FIR, free-free radiation star-formation Lyc photons H, H, … fast particles supernovae relativistic particles shock waves dynamo/SNe magnetic field synchrotron radiation

Bonn, Feb. 2018 2

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Radio continuum spectra of star-forming galaxies

assumed for decades: where and (optically thin case,   300 MHz)

) ( ) ( ) (   

syn ff tot

S S S  

1 . 0)

( ) (

             

ff ff

S S

syn

syn syn

S S

             

0)

( ) (

syn

Bonn, Feb. 2018 3

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Bonn, Feb. 2018 4

408 MHz 1400 MHz 2450 MHz 4750 MHz 8550 MHz H FIR

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measurements with Effelsberg 100-m telescope at 24 GHz, 1982 – 1984

5

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dwarf galaxies: II Zw 40, II Zw 70, IC 10, NGC 1569, NGC 4449 massive starburst galaxies: M 82, NGC 2146, NGC 3079, NGC 3310 interacting: M 51, NGC 4490, NGC 4631 mergers: NGC 4038, NGC 6052

6

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7

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8

with data  10.7 GHz

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9

with data  10.7 GHz

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10 Bonn, Feb. 2018

𝑇𝑡𝑧𝑜 𝜉 = 𝑇𝑔𝑔 𝜉0 ∙ 𝜉 𝜉0

−0.1

+ 𝑇𝑡𝑧𝑜 𝜉0 ∙ 𝜉 𝜉0

𝛽𝑡𝑧𝑜

∙ 𝑓

− 𝜉 𝜉𝑐

best fit (mostly):

!

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SLIDE 11

11 Bonn, Feb. 2018

𝑇𝑡𝑧𝑜 𝜉 = 𝑇𝑔𝑔 𝜉0 ∙ 𝜉 𝜉0

−0.1

+ 𝑇𝑡𝑧𝑜 𝜉0 ∙ 𝜉 𝜉0

𝛽𝑡𝑧𝑜

∙ 𝑓

− 𝜉 𝜉𝑐

best fit (mostly):

!

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SLIDE 12

12 Bonn, Feb. 2018

fitting synchrotron spectra: power-law, curved, break, cut-off

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13 Bonn, Feb. 2018

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fth(1 GHz) = 15% nth = -0.5

power-law + ff power-law with cut-off + ff

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fth(1 GHz) = 15% nth = -0.5 data: NGC 2146

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Bonn, Feb. 2018 16

fraction of thermal emission extinction

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nth : comparison with SNR (Green, 2014) spectra: nth of low-frequency galaxy spectra similar to nth of shell-type SNR < SNR> = 0.50, SNR = 0.33 < Gal > = 0.59, Gal = 0.20

Bonn, Feb. 2018 17

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SN(R) inject particles with power-law high-energy particles age quickly in thin disk migrate to low energy-regime are transported into halo may reside and radiate there for long time …

Bonn, Feb. 2018 18

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Conclusions:

revised radio continuum spectra

  • reveal broken power-laws of synchrotron spectra
  • indicate low containment of comic rays in dwarf

galaxies

  • exhibit low  SNR (must be checked with LOFAR!)
  • cut-off energies 1.5 - 7 GeV

more such work worthwhile: Effelsberg SRT!!! Greenbank

Bonn, Feb. 2018 19

Paper: Klein, Lisenfeld, Verley A&A, in press 2017arXiv171003149K