Fermi Large Area Telescope observations of Local Group galaxies: Detection of M31 and search for M33

The Fermi/LAT collaboration

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Fermi Large Area Telescope observations of Local Group galaxies: Detection of M31 and search for M33

The Fermi/LAT collaboration

High Energy Astrophysical Phenomena · Submitted 9 Dec 2010

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim Comparing these results to the properties of other Local Group galaxies, we find indications for a correlation between star formation rate and gamma-ray luminosity that also holds for the starburst galaxies.

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arXiv ID1012.1952 (version 1)

Pith IDZ5W7FI4S, Pith's permanent record of this paper and its review

CitationThe Fermi/LAT collaboration. "Fermi Large Area Telescope observations of Local Group galaxies: Detection of M31 and search for M33." arXiv:1012.1952 (2010). https://pith.science/paper/Z5W7FI4S

Claim paper

The compiled record

The paper's own sentences, arranged. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

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Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 8,481 input tokens, $0.0004 reported.

What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.80 · human participants 0.01 · controlled comparison 0.46 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.94 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; show every role.

Cosmic rays (CRs) can be studied through the galaxy-wide gamma-ray emission that they generate when propagating in the interstellar medium. The comparison of the diffuse signals from different systems may inform us about the key parameters in CR acceleration and transport. We aim to determine and compare the properties of the CR-induced gamma-ray emission of several Local Group galaxies. We use 2 years of nearly continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to search for gamma-ray emission from M31 and M33. We compare the results with those for the Large Magellanic Cloud, the Small Magellanic Cloud, the Milky Way, and the starburst galaxies M82 and NGC253. We detect a gamma-ray signal at 5sigma significance in the energy range 200 MeV-20 GeV that is consistent with originating from M31. The integral photon flux above 100MeV amounts to 9.1 +/- 1.9 (stat) +/- 1.0 (sys) x10e-9 ph/cm2/s. We find no evidence for emission from M33 and derive an upper limit on the photon flux >100MeV of 5.1 x10e-9 ph/cm2/s (2sigma). Comparing these results to the properties of other Local Group galaxies, we find indications for a correlation between star formation rate and gamma-ray luminosity that also holds for the starburst galaxies. The gamma-ray luminosity of M31 is about half that of the Milky Way, which implies that the ratio between the average CR densities in M31 and the Milky Way amounts to 0.35 +/- 0.25. The observed correlation between gamma-ray luminosity and star formation rate suggests that the flux of M33 is not far below the current upper limit from the LAT observations.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	Cosmic rays (CRs) can be studied through the galaxy-wide gamma-ray emission that they generate when propagating in the interstellar medium.	background 1.00	0.05	0.02	hedged possibility 0.58
s1	The comparison of the diffuse signals from different systems may inform us about the key parameters in CR acceleration and transport.	background 1.00	0.06	0.03	hedged possibility 0.97
s2	We aim to determine and compare the properties of the CR-induced gamma-ray emission of several Local Group galaxies.	contribution 0.96	0.23	0.03	asserted 0.60
s3	We use 2 years of nearly continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to search for gamma-ray emission from M31 and M33.	method 0.98	0.96	0.02	asserted 0.88
s4	We compare the results with those for the Large Magellanic Cloud, the Small Magellanic Cloud, the Milky Way, and the starburst galaxies M82 and NGC253.	method 0.78	0.81	0.02	asserted 0.75
s5	We detect a gamma-ray signal at 5sigma significance in the energy range 200 MeV-20 GeV that is consistent with originating from M31.	result 1.00	0.97	0.57	asserted 0.73
s6	The integral photon flux above 100MeV amounts to 9.1 +/- 1.9 (stat) +/- 1.0 (sys) x10e-9 ph/cm2/s.	result 1.00	0.95	0.07	asserted 1.00
s7	We find no evidence for emission from M33 and derive an upper limit on the photon flux >100MeV of 5.1 x10e-9 ph/cm2/s (2sigma).	result 1.00	0.97	0.12	asserted 1.00
s8	Comparing these results to the properties of other Local Group galaxies, we find indications for a correlation between star formation rate and gamma-ray luminosity that also holds for the starburst galaxies.	result 0.58	0.96	0.51	hedged possibility 0.84
s9	The gamma-ray luminosity of M31 is about half that of the Milky Way, which implies that the ratio between the average CR densities in M31 and the Milky Way amounts to 0.35 +/- 0.25.	interpretation 0.83	0.94	0.18	asserted 0.96
s10	The observed correlation between gamma-ray luminosity and star formation rate suggests that the flux of M33 is not far below the current upper limit from the LAT observations.	interpretation 0.99	0.75	0.16	hedged possibility 0.96

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from analysis of existing data 0.64.

What was examined, and what was not

sources read

arXiv listing abstract v1

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

not run

S sections
T body sentences
C citations
R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

The paper

Original abstract

Cosmic rays (CRs) can be studied through the galaxy-wide gamma-ray emission that they generate when propagating in the interstellar medium. The comparison of the diffuse signals from different systems may inform us about the key parameters in CR acceleration and transport. We aim to determine and compare the properties of the CR-induced gamma-ray emission of several Local Group galaxies. We use 2 years of nearly continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to search for gamma-ray emission from M31 and M33. We compare the results with those for the Large Magellanic Cloud, the Small Magellanic Cloud, the Milky Way, and the starburst galaxies M82 and NGC253. We detect a gamma-ray signal at 5sigma significance in the energy range 200 MeV-20 GeV that is consistent with originating from M31. The integral photon flux above 100MeV amounts to 9.1 +/- 1.9 (stat) +/- 1.0 (sys) x10e-9 ph/cm2/s. We find no evidence for emission from M33 and derive an upper limit on the photon flux >100MeV of 5.1 x10e-9 ph/cm2/s (2sigma). Comparing these results to the properties of other Local Group galaxies, we find indications for a correlation between star formation rate and gamma-ray luminosity that also holds for the starburst galaxies. The gamma-ray luminosity of M31 is about half that of the Milky Way, which implies that the ratio between the average CR densities in M31 and the Milky Way amounts to 0.35 +/- 0.25. The observed correlation between gamma-ray luminosity and star formation rate suggests that the flux of M33 is not far below the current upper limit from the LAT observations.

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References

Forward citations

Cited by 2 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

The origin of Galactic cosmic rays: challenges to the standard paradigm
astro-ph.HE 2019-03 accept novelty 3.0 of 10

Eight cosmic-ray specialists argue that the supernova-remnant plus diffusion paradigm no longer fits a decade of precise data, and list the observations that could decide whether it needs repair or replacement.
The nature of the Diffuse Gamma-Ray Background
astro-ph.CO 2015-02 accept novelty 3.0 of 10

The review concludes that known astrophysical populations can plausibly account for most of the Fermi LAT diffuse gamma-ray background, leaving limited but not excluded room for a dark matter contribution.

How the literature uses it

13 arXiv papers cite this in 19 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 14 sentences without a confident label

Uses its method or tool 1 paper

To derive the spectral energy distribution (SED) of M31, we divide the data into six energy bins from 200 MeV to 150 GeV (same as that done in [ref] ), and use gtlike to fit the parameters in each bin.

Constraints on the dark matter annihilation from Fermi-LAT observation of M31 · Data analysis · 0.90

Uses its data or values 1 paper

We will demonstrate the use of RX-DMFIT by performing our analysis on three scales: A cluster scale model emulating the Coma cluster, where we assume a redshift $z = 0.0232$ and diffusion zone $r_h = 415$ kpc [ref] ; a dwarf spheroidal model similar to the Draco dwarf with redshift corresponding to a distance of 80 kpc [ref] and a diffusion zone $r_h = 2.5$ kpc [ref] ; and finally a galactic scale model similar to M31 at a distance 780 kpc [ref] and with a diffusion zone radius of $r_h = 30$ kpc borrowing from analysis of the Milky Way [ref] .

Multiwavelength Analysis of Dark Matter Annihilation and RX-DMFIT · Parameter Selection · 0.98

Compares with it 2 papers

Also shown for comparison are the SED for point source assumption (black squares) and that given in [ref] based on two year data (red triangles).

Constraints on the dark matter annihilation from Fermi-LAT observation of M31 · Data analysis · 0.98
Detailed $γ$-ray analyses of these galaxies exist in the literature [ref] , and we will compare our results to these systems in the discussion.

Star-Forming Galaxies Significantly Contribute to the Isotropic Gamma-Ray Background · Gamma-Ray Data Analysis · 0.93

Cites it as background 1 paper

M31 was detected in gamma rays for the first time by Fermi-LAT during the first years of its operation [ref] .

Nature of M31 gamma-ray halo in relation to dark matter annihilation · Introduction and motivation · 0.84

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