Winds, Clumps, and Interacting Cosmic Rays in M82

Yoast-Hull, Tova M.; Everett, J. E.; Gallagher, J.; Zweibel, Ellen G.

doi:10.1088/0004-637x/768/1/53

Cited by 108 publications

(131 citation statements)

References 67 publications

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“…Assuming that nearly all electrons are confined inside the star-forming regions and supernova remnants, the filling factor f e can be calculated. Using a density of n e = 1000 cm −3 from Westmoquette et al (2009) for the star-forming regions leads to a filling factor of f e = 1.9%, which is confirmed by theoretical predictions from Yoast-Hull et al (2013). While these calculations suffer from a contribution to the integrated area of the disk emission in the front and on the back of the galaxy as well as the unknown morphology in the core region, they are good enough for an order of magnitude estimate.…”

Section: Disentangling the Core And Halo Emissionsupporting

confidence: 61%

M 82 – A radio continuum and polarisation study

Adebahr

Krause

Klein

et al. 2013

A&A

104

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Context. The potential role of magnetic fields and cosmic ray propagation for feedback processes in the early Universe can be probed by studies of local starburst counterparts with an equivalent star-formation rate. Aims. In order to study the cosmic ray propagation and determine the magnetic field strength and dominant loss processes in the nearby prototypical starbursting galaxy M 82, a multi-frequency analysis at four radio wavelengths is presented. Methods. Archival data from the Westerbork Synthesis Radio Telescope (WSRT) was reduced and a new calibration technique introduced to reach the high dynamic ranges needed for the complex source morphology. These data were combined with archival Very Large Array (VLA) data, yielding total power maps at λ3 cm, λ6 cm, λ22 cm, and λ92 cm. Results. The data show a confinement of the emission at wavelengths of λ3/λ6 cm to the core region and a largely extended halo reaching up to 4 kpc away from the galaxy midplane at wavelengths of λ22/λ92 cm up to a sensitivity limit of 90 µJy and 1.8 mJy respectively indicating different physical processes in the core and halo regions. The results are used to calculate the magnetic field strength to 98 µG in the core region and to 24 µG in the halo regions. From the observation of ionisation losses, the filling factor of the ionised medium could be estimated to 2%. This leads to a revised view of the magnetic field distribution in the core region and the propagation processes from the core into the halo regions. Conclusions. We find that the radio emission from the core region is dominated by very dense H -regions and supernova remnants, while the surrounding medium is filled with hot X-ray and neutral gas. Cosmic rays radiating at frequencies higher than 1.4 GHz suffer from high synchrotron and inverse Compton losses in the core region and are not able to reach the halo. Even the cosmic rays radiating at longer wavelengths are only able to build up the observed kpc-sized halo, when several starbursting periods are assumed where the far-infrared and radio luminosity vary by an order of magnitude. These findings, together with the strong correlation between Hα, ionised polycyclic aromatic hydrocarbons (PAH + ), and our radio continuum data, suggest a magnetic field which is frozen into the ionised medium and driven out of the galaxy kinematically.

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Section: Disentangling the Core And Halo Emissionsupporting

confidence: 61%

M 82 – A radio continuum and polarisation study

Adebahr

Krause

Klein

et al. 2013

A&A

104

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“…We approximate the effects of CR cooling due to Coulomb and hadronic losses due to pion production via (Yoast-Hull et al 2013), is the minimum energy of CRs, and μ e and μ p are the mean molecular weights per electron and proton, respectively. In the simulations, we assume n = 4.5 and mean proton Lorentz γ = 3.…”

Section: Icm Heating By Crsmentioning

confidence: 99%

Cosmic-Ray Feedback Heating of the Intracluster Medium

Ruszkowski

Yang

Reynolds

2017

ApJ

111

112

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Active galactic nuclei (AGNs) play a central role in solving the decades-old cooling-flow problem. Although there is consensus that AGNs provide the energy to prevent catastrophically large star formation, one major problem remains: How is the AGN energy thermalized in the intracluster medium (ICM)? We perform a suite of threedimensional magnetohydrodynamical adaptive mesh refinement simulations of AGN feedback in a cool core cluster including cosmic rays (CRs). CRs are supplied to the ICM via collimated AGN jets and subsequently disperse in the magnetized ICM via streaming, and interact with the ICM via hadronic, Coulomb, and streaming instability heating. We find that CR transport is an essential model ingredient at least within the context of the physical model considered here. When streaming is included, (i) CRs come into contact with the ambient ICM and efficiently heat it, (ii) streaming instability heating dominates over Coulomb and hadronic heating, (iii) the AGN is variable and the atmosphere goes through low-/high-velocity dispersion cycles, and, importantly, (iv) CR pressure support in the cool core is very low and does not demonstrably violate observational constraints. However, when streaming is ignored, CR energy is not efficiently spent on the ICM heating and CR pressure builds up to a significant level, creating tension with the observations. Overall, we demonstrate that CR heating is a viable channel for the AGN energy thermalization in clusters and likely also in ellipticals, and that CRs play an important role in determining AGN intermittency and the dynamical state of cool cores.

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“…I calculateεCR by scaling to the comoving cosmic star-formation rate density ρSFR (Hopkins & Beacom 2006 Lacki et al 2011;Yoast-Hull et al 2013). CRs may also be accelerated by galactic wind termination shocks, where the winds are powered by SNe and contain some fraction ǫSN of the original SN mechanical energy.…”

Section: The Pressure Of Intergalactic Cosmic Raysmentioning

confidence: 99%

The ultimate fate of cosmic rays from galaxies and their role in the intergalactic medium

Lacki

2015

Monthly Notices of the Royal Astronomical Society: Letters

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The majority of cosmic rays (CRs) generated by star-forming galaxies escape them and enter the intergalactic medium (IGM). Galactic wind termination shocks might also accelerate CRs. I show that the mean pressure of these CRs can reach to within an order of magnitude of the mean Lyman-α forest thermal pressure. At z > ∼ 1, their pressure may have even been dominant. I also demonstrate that, whichever IGM phase the CRs reside in, they contribute significantly to its pressure if its temperature is ∼ 10 4 K, as long as pionic and Coulomb losses are negligible. Where CRs end up depends on the structure and strength of intergalactic magnetic fields. I argue that CRs end up at least 30 kpc from their progenitor galaxies. CRs may self-confine in the IGM to the sound speed, generating > ∼ 10 −13 G magnetic fields. These considerations imply the existence and importance of a nonthermal IGM.

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Winds, Clumps, and Interacting Cosmic Rays in M82

Cited by 108 publications

References 67 publications

M 82 – A radio continuum and polarisation study

M 82 – A radio continuum and polarisation study

Cosmic-Ray Feedback Heating of the Intracluster Medium

The ultimate fate of cosmic rays from galaxies and their role in the intergalactic medium

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