Search for Gamma-ray emission from Abell 119 galaxy cluster using INTEGRAL/ISGRI, COMPTEL, and DAMPE data

arXiv:2602.23686 · astro-ph.HE, astro-ph.CO · Submitted 2026-02-27 · Read on arXiv

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Introduction to the show: ident: Astrophysics Radio. Generated commentary on the latest astrophysics papers.

Vera: Today's paper: "Search for Gamma-ray emission from Abell 119 galaxy cluster using INTEGRAL/ISGRI, COMPTEL, and DAMPE data".

Jocelyn: The gist The comprehensive search for non-thermal high-energy γ-ray emission from Abell 119 galaxy cluster using INTEGRAL/ISGRI, COMPTEL, and DAMPE data found no statistically significant emission in any energy band.

Vera: First, who's behind it and why it matters.

Paper summary: Vera: So we’re looking at this paper, "Search for Gamma-ray emission from Abell one hundred nineteen galaxy cluster using INTEGRAL/ISGRI, COMPTEL, and DAMPE data <ref:2602.23686#pg1,Search for Gamma-ray emission from Abell 119 galaxy cluster using INTEGRAL>." It really shows how much work they put into searching for this signal across different energy ranges.

Jocelyn: They're combining hard X-ray data from INTEGRAL/ISGRI between thirty and one hundred keV with MeV gamma ray observations from COMPTEL covering zero point seven five to thirty MeV, and then layering on the GeV to TeV data from DAMPE which covers up to one TeV <ref:2602.23686#pg1,hard X-ray data from INTEGRAL/ISGRI>.

Subrahmanyan: The thesis here is that they are looking for this non-thermal high-energy gamma-ray emission specifically from Abell one hundred nineteen which is a merging galaxy cluster at redshift zero point zero four four (z = zero point zero four four) > <ref:2602.23686#pg1>

Vera: And the main finding across all these combined observations is that no statistically significant emission was detected at the cluster position in any of those energy bands. That’s the key takeaway for this search.

Jocelyn: They quantify this by giving upper limits: a three sigma upper limit on the hard X-ray flux from ISGRI of F30–one hundred keV is less than or equal to eight point five times ten to the minus eleven erg cm minus squared per second, and a range of ninety-five percent confidence level upper limits from COMPTEL between about nine times ten to the minus eleven and about eight times ten to the minus ten erg cm minus squared per second across zero point zero seven five to thirty MeV > <ref:2602.23686#pg1,95% confidence level upper limits>

Subrahmanyan: The significance of those numbers is that they provide independent multi-band constraints on the reported GeV excess from recent Fermi-LAT studies, which is a way to test if the emission mechanism they’re seeing in one energy range actually has to be consistent across others >

Vera: So looking at the title again, "Search for Gamma-ray emission from Abell one hundred nineteen galaxy cluster using INTEGRAL/ISGRI, COMPTEL, and DAMPE data <ref:2602.23686#pg1,Search for Gamma-ray emission from Abell 119 galaxy cluster using INTEGRAL>." It really shows how thorough they were in searching for this signal.

Jocelyn: The authors, Manna and Desai, they put together a very specific methodology by spanning seven decades of photon energy using those three major instruments to look for non-thermal processes >

Subrahmanyan: What this means for the bigger picture is that even with some reported excess in other studies, this paper suggests that any non-thermal emission from Abell one hundred nineteen is still tentative because it hasn't been confirmed across the keV through GeV bands > <ref:2602.23686#pg1>

Vera: So to put it simply, they’ve searched hard X-rays, MeV gamma rays, and TeV gamma rays simultaneously using archival data and found nothing conclusive at the cluster center >

Jocelyn: That lack of confirmation across those three major energy regimes is what makes this result so important for anyone studying galaxy clusters today. It sets a very strict benchmark for what we expect to see from these systems >

Subrahmanyan: It tells us that if there is non-thermal emission happening in Abell one hundred nineteen it’s either very faint or its spectrum might be changing with energy in a way that these specific instruments didn't catch robustly yet > <ref:2602.23686#pg1>

Conclusion: Vera: So we've looked at all that data across hard X-rays, MeV gamma rays, and TeV gamma rays from Abell one hundred nineteen using INTEGRAL, COMPTEL, and DAMPE—and the main point here is that they found no statistically significant non-thermal emission anywhere.

Jocelyn: Exactly. The authors Manna and Desai put together this really detailed search spanning seven decades of energy, trying to rule out any hidden gamma-ray signal from this merging cluster at redshift zero point zero four four.

Subrahmanyan: What that means is that for a system like Abell one hundred nineteen which is a classic merging cluster, we can't yet confirm the presence of strong particle acceleration producing these high-energy photons across all those energy bands simultaneously.

Vera: It’s not about finding emission; it’s about setting very clear upper limits on how much non-thermal radiation could possibly be there.

Jocelyn: They found these upper limits, for instance, a three sigma limit on the hard X-ray flux from ISGRI being less than eight point five times ten to the minus eleven erg cm minus squared per second.

Subrahmanyan: That’s a concrete number showing how faint we have to expect this non-thermal process to be if it exists at all.

Vera: And that lack of confirmation across keV through GeV bands is what makes this result so important for anyone studying these massive structures today.

Jocelyn: It sets a very strict benchmark for what we expect to see from galaxy clusters when we look for those high-energy signatures, which is crucial for our understanding of cosmic particle physics.

Subrahmanyan: So if there is non-thermal emission happening in Abell one hundred nineteen it’s either extremely faint or its spectrum might be changing with energy in a way that these specific instruments didn't catch robustly yet.

Vera: We know that the next step for this kind of investigation involves looking at new facilities, like those planned MeV observatories or better GeV to TeV detectors, to try and push those limits even further out.

Department of Physics, IIT Hyderabad Kandi

astro-ph.HE, astro-ph.CO

Submitted: 2026-02-27

Updated: 2026-10-09

Comments: 11 pages, 4 figures. Published in the Open Journal of Astrophysics

License: http://creativecommons.org/licenses/by/4.0/

Importance score: 69/100

The gist: The gist The comprehensive search for non-thermal high-energy γ-ray emission from Abell 119 galaxy cluster using INTEGRAL/ISGRI, COMPTEL, and DAMPE data found no statistically significant emission

Key concepts

INTEGRAL/ISGRI: This instrument on the INTEGRAL satellite observes hard X-rays (30–100 keV). The researchers used its data to search for high-energy emission from the galaxy cluster's location. They analyzed images across several energy bands to look for any signal above background noise.
COMPTEL: The Imaging Compton Telescope (COMPTEL) observes MeV gamma-rays (0.75–30 MeV). This instrument was used to search for non-thermal emission in the medium energy range. The analysis showed no statistically significant gamma-ray signal from Abell 119 in this band.
DAMPE: The Dark Matter Particle Explorer (DAMPE) observes GeV–TeV gamma-rays (3 GeV–1 TeV). This instrument was used to search for the highest energy non-thermal emission. The analysis placed upper limits on the flux, showing no significant detection of gamma rays from the cluster.
Statistical Significance ($\sigma$): This is a measure used to determine if an observed signal is likely real or just random noise. A 5$\\sigma$ result is typically considered a strong detection. In this study, all searches failed to reach the 5$\\sigma$ threshold, meaning no statistically significant emission was found in any energy band.

Terminology

Abell 119 — 1× in this paper · explained in 1 episode

Summary

The gist The comprehensive search for non-thermal high-energy γ-ray emission from Abell 119 galaxy cluster using INTEGRAL/ISGRI, COMPTEL, and DAMPE data found no statistically significant emission in any energy band.

Search Strategy

The researchers conducted a comprehensive broadband search for non-thermal high-energy emission from Abell 119 spanning hard X-rays to TeV energies using archival observations from INTEGRAL/ISGRI (30–100 keV), COMPTEL (0.75–30 MeV), and DAMPE (3 GeV–1 TeV) The analysis combined data from INTEGRAL/ISGRI [30, 31], COMPTEL [32], and DAMPE [33–35] providing energy coverage from ∼30 keV to 1 TeV Each instrument was analyzed independently using its standard data reduction and statistical framework

INTEGRAL/ISGRI Analysis

The search for hard X-ray and soft γ-ray emission from Abell 119 was conducted using the ISGRI detector of the IBIS instrument [30] onboard INTEGRAL [31] All publicly available Science Windows (ScWs) covering the position of Abell 119 (RA = 14.035◦, Dec = −1.200◦, J2000) were retrieved from the INTEGRAL Science Data Archive 1 The imaging analysis was configured to produce sky mosaics in four logarithmically spaced energy bands: 30–41, 41–54.5, 54.5–73.5, and 73.5–99.5 keV The statistical significance at the source position was obtained directly from the ISGRI mosaic significance maps produced by ii skyimage, which provide the significance in units of Gaussian standard deviations In all the four energy bands, the significance at the cluster center remains well below the canonical 5σ detection threshold, with values ranging from (0-1.2)σ Based on these null detections, they derive 3σ upper limits on the hard X-ray flux from Abell 119 of F3σ(30–100 keV) = 8.5 × 10−11 erg cm−2 s−1

COMPTEL MeV Gamma-Ray Analysis

The search for MeV γ-ray emission from Abell 119 was conducted using archival data from the Imaging Compton Telescope (COMPTEL) aboard the Compton Gamma Ray Observatory (CGRO) The analysis performed two independent likelihood analyses with complementary energy binning strategies to test for potential emission while maximizing statistical robustness Both analyses consistently indicate no statistically significant MeV γ-ray emission from Abell 119 The 95% upper limits on the integrated energy flux range from ∼ 9 × 10−11 to ∼ 8 × 10−10 erg cm−2 s−1, with the most stringent constraints obtained in the 0.75–1.89 MeV band

DAMPE GeV–TeV Gamma-Ray Analysis

The broadband fit models potential emission from Abell 119 as a point source centered at the cluster coordinates (RA = 14.035◦, Dec = −1.200◦, J2000) with a power-law spectrum No statistically significant emission is detected from the cluster position In all DAMPE energy bins, the TS values remain far below the canonical detection threshold of TS = 25, indicating no significant γ-ray emission from Abell 119 The resulting SED plot shows upper limits spanning nearly two orders of magnitude, from ∼ 10−12 to ∼ 10−10 erg cm−2 s−1 between 3 GeV and 1 TeV

Combined Analysis and Conclusion

The combined analysis of Abell 119 spanning hard X-rays to TeV energies incorporates archival observations from Swift/BAT, INTEGRAL/ISGRI, COMPTEL, DAMPE, and Fermi-LAT The resulting SED of Abell 119 spans over seven decades in energy Both studies independently exclude any significant hard X-ray excess above thermal intracluster emission, placing stringent constraints on inverse Compton or synchrotron emission from relativistic electrons in the cluster The absence of confirmation across keV–MeV–GeV bands indicates that any non-thermal emission from Abell 119 remains tentative Definitive conclusions await next-generation MeV observatories such as COSI, AMEGO-X as well as improved GeV–TeV facilities (such as CTA)

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INTEGRAL/ISGRI Analysis

Improvements for AI systems

Bold Header: Advanced Multi-Wavelength Source Localization and Constraint Mapping

The improved system can perform a comprehensive search for non-thermal high-energy γ-ray emission from Abell 119 using archival observations spanning over seven decades in photon energy by combining data from INTEGRAL/ISGRI, COMPTEL, and DAMPE. This allows the AI to produce a combined SED of Abell 119 spanning over seven decades in energy, enabling a direct visual and quantitative assessment of the compatibility between the tentative GeV excess reported by Harale and Paul [22] and the non-thermal upper limits derived from hard X-ray and MeV–TeV observations.

Bold Header: Model-Independent Flux Upper Limit Derivation

The system can derive stringent constraints on emission using a model-independent, image-based methodology employed here, specifically focusing on deriving 3σ upper limits by extracting the mosaic variance map to determine the count-rate uncertainty, which is then converted into a physical energy flux using an empirical calibration based on the Crab Nebula spectrum.

Bold Header: Cross-Instrument Spectral Consistency Testing

The improved system can test for spectral consistency by performing a combined analysis of Abell 119 spanning hard X-rays to TeV energies, plotting fluxes at the geometric mean energy of each bin and comparing the results across different instruments (Swift/BAT, INTEGRAL/ISGRI, COMPTEL, DAMPE) to assess physical plausibility.

Abstract

We present a comprehensive search for non-thermal high-energy γ-ray emission from the nearby merging galaxy cluster Abell 119 (z=0.044) using archival observations spanning over seven decades in photon energy. Our analysis combines hard X-ray data from INTEGRAL/ISGRI (30--100 keV), MeV γ-ray observations from COMPTEL (0.75--30 MeV), and GeV--TeV data from the DArk Matter Particle Explorer (DAMPE; 3 GeV--1 TeV). No statistically significant emission is detected at the cluster position in any energy band. In the hard X-ray regime, we derive a 3σ upper limit of F 30-100, keV 8.5 times 10-11 erg cm-2 s-1 from ISGRI mosaic imaging. Reanalysis of archival COMPTEL data yields 95% confidence-level upper limits ranging from about 9 times 10-11 to about 8 times 10-10 erg cm-2 s-1 across 0.75--30 MeV. In the GeV--TeV range, DAMPE differential energy flux to about 10-12 -- 10-10 erg cm-2 s-1 (95% confidence level). These results provide independent multi-band constraints on the reported GeV excess from recent Fermi-LAT studies. While our DAMPE limits do not exclude the flux levels claimed in those analyses, the absence of confirmation across keV--MeV--GeV bands indicates that any non-thermal emission from Abell 119 remains tentative.