Extragalactic gamma-ray background from star-forming galaxies: Will empirical scalings suffice?

Komis, Ioannis; Pavlidou, V.; Zezas, A.

doi:10.1093/mnras/sty3354

Cited by 10 publications

(7 citation statements)

References 58 publications

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“…Gamma-ray flux from a galaxy has been modeled in a number of studies to predict the cosmic gamma-ray background from star forming galaxies (Strong et al 1976;Lichti et al 1978;Dar & Shaviv 1995;Pavlidou & Fields 2002;Thompson et al 2007;Ando & Pavlidou 2009;Fields et al 2010;Makiya et al 2011;Stecker & Venters 2011;Ackermann et al 2012a;Chakraborty & Fields 2013;Lacki et al 2014;Komis et al 2017;Lamastra et al 2017), and most studies estimated gammaray luminosity only from one or two physical quantities (e.g. SFR, gas mass, or infrared luminosity) assuming empirical relations.…”

Section: Introductionmentioning

confidence: 99%

High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data

Sudoh

Totani

Kawanaka

2018

Publications of the Astronomical Society of Japan

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We present a new theoretical modeling to predict luminosity and spectrum of gamma-ray and neutrino emission of a star-forming galaxy, from star formation rate (ψ), gas mass (M gas ), stellar mass, and disk size, taking into account production, propagation and interactions of cosmic rays. The model reproduces the observed gamma-ray luminosities of nearby galaxies detected by Fermi better than the simple power-law models as a function of ψ or ψM gas . Then this model is used to predict the cosmic background flux of gamma-ray and neutrinos from star-forming galaxies, by using a semi-analytical model of cosmological galaxy formation that reproduces many observed quantities of local and high-redshift galaxies. Calibration of the model using gamma-ray luminosities of nearby galaxies allows us to make a more reliable prediction than previous studies. In our baseline model star-forming galaxies produce about 20% of isotropic gamma-ray background unresolved by Fermi, and only 0.5% of IceCube neutrinos. Even with an extreme model assuming a hard injection cosmic-ray spectral index of 2.0 for all galaxies, at most 22% of IceCube neutrinos can be accounted for. These results indicate that it is difficult to explain most of IceCube neutrinos by star-forming galaxies, without violating the gamma-ray constraints from nearby galaxies.

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Section: Introductionmentioning

confidence: 99%

High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data

Sudoh

Totani

Kawanaka

2018

Publications of the Astronomical Society of Japan

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“…[3,39]), though it is consistent with the conclusion of Refs. [5] and [40] that, in the absence of either a physical model for the γ-ray emission of SFGs or a much larger sample of resolved galaxies, it is not possible to rule them out as a dominant contributor. It is nonetheless instructive to examine the precise reasons why our conclusions differ from some earlier work.…”

Section: Discussionmentioning

confidence: 99%

Star-forming galaxies dominate the diffuse, isotropic γ-ray background

Roth

Krumholz

Crocker

et al. 2020

Preprint

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The Fermi Gamma Ray Space Telescope has revealed a diffuse, isotropic γ-ray background at energies ranging from 0.1 GeV to 1 TeV [1] whose astrophysical sources remain uncertain. Previous efforts to understand the origin of this background have been hampered by the lack of physical models capable of predicting the γ-ray emission produced by the many candidate sources, which include star-forming galaxies (SFGs) [2–6], active galactic nuclei (particularly blazars [7–9]), millisecond pulsars[7], and dark matter annihilation [10]. In the absence of predictive models, estimates of the contribution from potential sources have relied on a highly-uncertain process of empirically scaling the emission from a small sample of local, resolved sources by their estimated cosmological abundances. Here we present the first calculation of the contribution of SFGs to the γ-ray background that is based on a physical model for the γ-ray emission produced when cosmic ray ions accelerated in supernova remnants interact with the interstellar medium [11]. We validate the model by showing that it reproduces the γ-ray spectra, source count distribution and far infrared-γ-ray correlation observed for nearby, resolved SFGs. When we apply the model to the observed cosmological SFG population, we recover an excellent match to the γ-ray background from 1 GeV to 1 TeV. Our result shows that SFGs alone can explain the full diffuse γ-ray background over this energy range, and strongly suggests that emission in excess of our model at energies <1 GeV originates from cosmic ray electrons produced in the same galaxies.

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“…Models indicate that multiple source classes meaningfully contribute ( > ∼ 10%) to the total γ-ray luminosity of our universe. Moreover, the extragalactic γ-ray luminosity (EGRB) is relatively equally divided into emission between a handful of extremely bright point sources [1][2][3][4][5], and an underlying sea of dim sources, known collectively as the isotropic γ-ray background (IGRB) [6][7][8][9][10][11][12][13]. While the latter coincidence depends on the sensitivity of the instrument (in this case the Fermi-LAT), population models and statistical studies [6,[14][15][16][17][18] indicate that the distinction is also physically meaningful, with significant and distinct contributions from very bright and very dim sources.…”

Section: Introductionmentioning

confidence: 99%

Gamma-Rays from Star Forming Activity Appear to Outshine Misaligned Active Galactic Nuclei

Blanco¹,

Linden²

2021

Preprint

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The total extragalactic γ-ray flux provides a powerful probe into the origin and evolution of the highest energy processes in our universe. An important component of this emission is the isotropic γ-ray background (IGRB), composed of sources that cannot be individually resolved by current experiments. Previous studies have determined that the IGRB can be dominated by either misaligned active galactic nuclei (mAGN) or star-forming galaxies (SFGs). However, these analyses are limited, because they have utilized binary source classifications and examined only one source class at a time. We perform the first combined joint-likelihood analysis that simultaneously correlates the γ-ray luminosity of extragalactic objects with both star-formation and mAGN activity. We find that SFGs produce 48 +33 −20 % of the total IGRB at 1 GeV and 56 +40 −23 % of the total IGRB at 10 GeV. The contribution of mAGN is more uncertain, but can also be significant. Future work to quantify the radio and infrared properties of nearby galaxies could significantly improve these constraints.

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Extragalactic gamma-ray background from star-forming galaxies: Will empirical scalings suffice?

Cited by 10 publications

References 58 publications

High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data

High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data

Star-forming galaxies dominate the diffuse, isotropic γ-ray background

Gamma-Rays from Star Forming Activity Appear to Outshine Misaligned Active Galactic Nuclei

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