Multimessenger Model for the Starburst Galaxy M82

Pozo, E. De Cea del; Torres, D. F.; Marrero, Ana Y. Rodríguez

doi:10.1088/0004-637x/698/2/1054

Cited by 86 publications

(117 citation statements)

References 66 publications

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“…These include the detection of three nearby starburst galaxies, NGC 253, NGC 3034 (M 82), and NGC 5945, in the GeV (Ackermann et al 2012) and TeV (Acero et al 2009;Acciari et al 2009;Lenain et al 2010) regions. Measured fluxes from these galaxies agree with earlier theoretical predictions (NGC 253: Domingo-Santamaría & Torres 2005;Rephaeli et al 2010;NGC 3034: Persic et al 2008;de Cea et al 2009;NGC 4945: Lenain et al 2010) based on convection-diffusion models for proton and electron propagation and energy losses. While there were appreciable differences in the models treated in those works, predicted values for U p in the SBNs of the three galaxies were around 250 eV cm −3 .…”

Section: Introductionsupporting

confidence: 86%

“…Secondary electrons (and positrons, produced in π ± decays following pp collisions) initially have a slightly flatter spectrum (by Δq 0.2) than the parent proton spectrum for energies 1 GeV, but then their spectrum steepens due to severe energy losses. Detailed numerical models of emission from starburst galaxies show that primary and secondary electrons have roughly similar spectral shapes at energies ∼10 MeV-1 TeV (e.g., Domingo-Santamaría & Torres 2005;De Cea del Pozo et al 2009;Rephaeli et al 2010). Therefore, in the relatively small SBN region, where energetic particles have not yet ventured out too far from their acceleration sites, it is quite reasonable (for our purposes here) to characterize their spectra with the same index.…”

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confidence: 99%

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Estimates of relativistic electron and proton energy densities in starburst galactic nuclei from radio measurements

Peršić

Rephaeli

2014

A&A

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The energy density of energetic protons, U p , in several nearby starburst nuclei (SBNs) has been directly deduced from γ-ray measurements of the radiative decay of π 0 produced in interactions with ambient protons. Lack of sufficient sensitivity and spatial resolution makes this direct deduction unrealistic in the foreseeable future for even a moderately distant SBN. A more viable indirect method for determining U p in star-forming galaxies is to use its theoretically based scaling to the energy density of energetic electrons, U e , which can be directly deduced from radio synchrotron and possibly also nonthermal hard X-ray emission. In order to improve the quantitative basis and diagnostic power of this leptonic method we reformulate and clarify its main aspects. Doing so we obtain a basic expression for the ratio U p /U e in terms of the proton and electron masses and the power-law indices that characterize the particle spectral distributions in regions where the total particle energy density is at equipartition with that of the mean magnetic field. We also express the field strength and the particle energy density in the equipartition region in terms of the region's size, mean gas density, IR and radio fluxes, and distance from the observer, and determine values of U p in a sample of nine nearby and local SBNs.

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Section: Introductionsupporting

confidence: 86%

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confidence: 99%

Estimates of relativistic electron and proton energy densities in starburst galactic nuclei from radio measurements

Peršić

Rephaeli

2014

A&A

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“…The simulated Figure 9: Simulation of 30h CTA observations (array configuration I) for the starburst galaxy M82. The curves represents the predicted emission and the data points based on the measured spectrum from M82 and a spectral model of [82].…”

Section: Starburst Galaxies and Galaxy Clustermentioning

confidence: 99%

“…spectrum is based on the model presented in [82]. It is evident that, if present, a cutoff in the TeV energy range will be easily identified by CTA.…”

Section: Starburst Galaxies and Galaxy Clustermentioning

confidence: 99%

Gamma-ray signatures of cosmic ray acceleration, propagation, and confinement in the era of CTA

Acero

Bamba

Casanova

et al. 2013

Astroparticle Physics

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Galactic cosmic rays are commonly believed to be accelerated at supernova remnants via diffusive shock acceleration. Despite the popularity of this idea, a conclusive proof for its validity is still missing. Gamma-ray astronomy provides us with a powerful tool to tackle this problem, because gamma rays are produced during cosmic ray interactions with the ambient gas. The detection of gamma rays from several supernova remnants is encouraging, but still does not constitute a proof of the scenario, the main problem being the difficulty in disentangling the hadronic and leptonic contributions to the emission. Once released by their sources, cosmic rays diffuse in the interstellar medium, and finally escape from the Galaxy. The diffuse gamma-ray emission from the * Principal corresponding author, stefano.gabici@apc.univ-paris7.fr, tel. +33157277024, fax. +33157276071 * * Corresponding author Galactic disk, as well as the gamma-ray emission detected from a few galaxies is largely due to the interactions of cosmic rays in the interstellar medium. On much larger scales, cosmic rays are also expected to permeate the intracluster medium, since they can be confined and accumulated within clusters of galaxies for cosmological times. Thus, the detection of gamma rays from clusters of galaxies, or even upper limits on their emission, will allow us to constrain the cosmic ray output of the sources they contain, such as normal galaxies, AGNs, and cosmological shocks. In this paper, we describe the impact that the Cherenkov Telescope Array, a future ground-based facility for very-high energy gamma-ray astronomy, is expected to have in this field of research.

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“…Furthermore, because the gamma rays are a recent discovery, our understanding of CRs is at a basic, phenomenological level. Thus, much of the theoretical work about CRs in starbursts uses one-zone steady-state models (Paglione et al 1996;Torres 2004;Domingo-Santamaría & Torres 2005;de Cea del Pozo et al 2009;Lacki et al 2010). These assume that the interstellar medium (ISM), magnetic fields, and CR injection of starbursts are completely homogeneous -essentially, that starbursts have no structure, which is obviously not true in detail.…”

Section: Introductionmentioning

confidence: 99%

From 10K to 10 TK: Insights on the Interaction Between Cosmic Rays and Gas in Starbursts

Lacki

2013

Cosmic Rays in Star-Forming Environments

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Recent work has both illuminated and mystified our attempts to understand cosmic rays (CRs) in starburst galaxies. I discuss my new research exploring how CRs interact with the ISM in starbursts. Molecular clouds provide targets for CR protons to produce pionic gamma rays and ionization, but those same losses may shield the cloud interiors. In the densest molecular clouds, gamma rays and 26 Al decay can provide ionization, at rates up to those in Milky Way molecular clouds. I then consider the free-free absorption of low frequency radio emission from starbursts, which I argue arises from many small, discrete H II regions rather than from a "uniform slab" of ionized gas, whereas synchrotron emission arises outside them. Finally, noting that the hot superwind gas phase fills most of the volume of starbursts, I suggest that it has turbulent-driven magnetic fields powered by supernovae, and that this phase is where most synchrotron emission arises. I show how such a scenario could explain the far-infrared radio correlation, in context of my previous work. A big issue is that radio and gamma-ray observations imply CRs also must interact with dense gas. Understanding how this happens requires a more advanced understanding of turbulence and CR propagation.

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Multimessenger Model for the Starburst Galaxy M82

Cited by 86 publications

References 66 publications

Estimates of relativistic electron and proton energy densities in starburst galactic nuclei from radio measurements

Estimates of relativistic electron and proton energy densities in starburst galactic nuclei from radio measurements

Gamma-ray signatures of cosmic ray acceleration, propagation, and confinement in the era of CTA

From 10K to 10 TK: Insights on the Interaction Between Cosmic Rays and Gas in Starbursts

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