[astro-ph.GA] Galactic observations have shown that N2H+ intensities preferentially trace star-forming dense molecular gas compared with HCN or HCO+, which are conventionally used as dense-gas tracers in extragalactic studies.
![(Left) The N2H +/HCN ratio toward the central region of M83 shown in the color scale. The black contours show 3-mm continuum intensities with 0.5 mJy beam−1 increments. The beam size is shown at the bottom left corner. (Right) The same figure as Figure 2(a), but including data points from the galactic center region. The grey dashed lines have slopes of 1, and show the lines of constant N2H +/HCN ratios. -- [astro-ph.GA]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/10/ALMA-observations.png?resize=1200%2C722&ssl=1)
[astro-ph.GA] Galactic observations have shown that N2H+ intensities preferentially trace star-forming dense molecular gas compared with HCN or HCO+, which are conventionally used as dense-gas tracers in extragalactic studies.