Chérif F. Matta | Searcharxiv

arXiv2025

Potential Vibrational Modes Tied to Diffuse Interstellar Bands

Potential vibrational modes associated with diffuse interstellar bands (DIBs) could be discerned by examining energy differences between correlated DIBs. Consequently, $\approx 10^3$ higher correlated DIB pairs ($r-σ_r \ge 0.8$, $\ge 12$ sightlines) were extracted from the Apache Point Observatory DIB catalog, and their energy spacings computed. In this first macro exploratory step, a histogram possibly reveals chemical bond signatures of C$\equiv$C, C$\equiv$N, S$-$H, C$-$O, C$=$O, Si$-$H, N$-$H, C$-$H (aliphatic), C$\mathbf{^{\underline{...}}}$C (in-ring), and aromatics (C$-$H stretch, C$\mathbf{^{\underline{...}}}$C in-ring, oop C$-$H bending, and overtones). Continued research is required to (in)validate the histogram approach, mitigate noise, scrutinize maxima, break degeneracies, and converge upon an optimal framework.

astro-ph.GA↗

arXiv2025

Strengthening the Link Between Fullerenes and a Subset of Diffuse Interstellar Bands

A debate persists regarding the correlation between the DIBs 9577 and 9632 Å, and whether they share a common molecular carrier (i.e., C$_{60}^{+}$). A robust high correlation determination emerges after bridging the baseline across an order of magnitude ($\simeq 50 - 700$ mÅ, $r=0.93\pm0.02$), and nearly doubling the important higher equivalent width domain by adding new Mg II-corrected sightlines. Moreover, additional evidence is presented of possible DIB linkages to fullerenes, whereby attention is drawn to DIBs at 7470.38, 7558.44, and 7581.47 Å, which match the Campbell experimental results for C$_{70}^{+}$ within 1 Å, and the same is true of 6926.48 and 7030.26 Å for C$_{70}^{2+}$. Yet their current correlation uncertainties are unsatisfactory and exacerbated by expectedly low EWs (e.g., $\overline{EW}=4$ mÅ for 6926.48 Å), and thus further observations are required to assess whether they represent a bona fide connection or numerical coincidence.

astro-ph.GA↗