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

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.