[Paper Review] DRAGON2_Optimized_DM&Antinuclei

Pedro De la Torre Luque|arXiv (Cornell University)|Jul 25, 2023

Gamma-ray bursts and supernovaePhysics and Astronomy3 citations

TL;DR

This study uses XMM-Newton X-ray observations to set the strongest constraints to date on electrophilic feebly interacting particles (FIPs) with MeV-scale masses produced in galactic supernovae. By modeling FIP decays into electron-positron pairs and their inverse-Compton emission on the interstellar photon background, the authors derive robust upper limits on FIP production, outperforming existing 511 keV line constraints by a factor of up to ~3 in sensitivity for the MOS detector data.

ABSTRACT

During galactic Supernova (SN) explosions, a large amount of feebly interacting particles (FIPs) may be produced. In this work we analyze electrophilic FIPs with masses in the MeV-range that escape from SN and decay into electron-positron pairs, causing an exotic leptonic injection. This contribution adds up to known components, leading to an unexpected excess of X-ray fluxes generated by inverse-Compton scattering of the injected particles on low-energy photon backgrounds. For the first time in the context of FIPs, we use XMM-Newton X-ray measurements to obtain the strongest and most robust bounds on electrophilic FIPs produced by SN in our Galaxy.

Motivation & Objective

• To establish new, robust constraints on electrophilic feebly interacting particles (FIPs) with MeV-scale masses produced in galactic supernovae.
• To investigate the inverse-Compton emission from electron-positron pairs injected by FIP decays, as a novel probe of FIP phenomenology.
• To evaluate the impact of plasma turbulence on electron/positron reacceleration and its effect on X-ray signal predictions.
• To compare the sensitivity of XMM-Newton X-ray data with existing bounds from the 511 keV line (SPI, Voyager-1) and assess its superiority in constraining FIP couplings.

Proposed method

• Modeling electrophilic FIP decays into e+e− pairs with masses below ~20 MeV, assuming dominant decay width into electron-positron pairs.
• Simulating inverse-Compton scattering of injected leptons on the interstellar radiation field to predict X-ray emission in the 2.5–8 keV range.
• Using XMM-Newton MOS detector observations to constrain the total number of electron-positron pairs injected per supernova, Nₑ.
• Accounting for systematic uncertainties from electron/positron reacceleration due to plasma turbulence, with Alfvén speed variations from ~10 to 40 km/s.
• Deriving bounds on FIP-electron coupling strength g via scaling Nₑ ∼ g^α, with α ≈ 1.5–1.6 for sterile neutrinos and α = 2 for dark photons.
• Comparing constraints from XMM-Newton with existing limits from SPI (511 keV line), Voyager-1, and SPI latitude/longitude profiles.

Figure 1: Limits on the production of electrons-positrons from FIP decays at $95\%$ Confidence Level (C.L.). We compare the limits derived from the fit to Voyager-1 data (blue), SPI latitude (green) and longitude (cyan) profiles, from Ref. De la Torre Luque et al. , with the ones obtained in this wo

Experimental results

Research questions

• RQ1 Can XMM-Newton X-ray observations provide stronger constraints on electrophilic FIPs than existing 511 keV line measurements?
• RQ2 How does reacceleration of injected electrons and positrons by plasma turbulence affect the predicted inverse-Compton X-ray signal from FIP decays?
• RQ3 What is the sensitivity of XMM-Newton MOS data to FIP production rates in galactic supernovae, and how does it compare to other observables?
• RQ4 To what extent do XMM-Newton constraints improve bounds on FIP-electron coupling strengths g for sterile neutrinos and dark photons?
• RQ5 Can FIP decays into e+e− pairs produce detectable X-ray emission that exceeds observed XMM-Newton fluxes, and what does this imply for FIP models?

Key findings

• XMM-Newton MOS data provide the most stringent constraints to date on the number of electron-positron pairs injected by FIP decays, with upper limits on Nₑ improved by a factor of ~3 compared to the leading 511 keV line bound.
• The XMM-Newton constraint from the MOS detector (red in Fig. 1) surpasses the 511 keV line constraint from SPI longitude profiles (cyan), indicating higher sensitivity in the MeV FIP regime.
• Systematic uncertainties from electron/positron reacceleration due to plasma turbulence are quantified, with the uncertainty band on the MOS constraint shown as a red hatched region.
• For sterile neutrinos (α ≈ 1.5–1.6) and dark photons (α = 2), the improved Nₑ bound translates into a factor of up to ~2 improvement in constraints on FIP-electron coupling g.
• The study demonstrates that XMM-Newton hard X-ray data offer a powerful, complementary probe to cosmological and 511 keV line constraints for FIPs coupled to electrons and positrons.
• The results open a new path for future searches of electron- and positron-coupled particles beyond the Standard Model in astrophysical X-ray spectra.

Figure 2: Comparison of the predicted X-ray signals generated from electrophilic FIPs from $1$ to $8$ keV, compared to the data from the MOS detector (XMM-Newton) for the rings 3 (the most constraining), in the left panel, and ring 30 (the less constraining), in the right panel. We show the predicte