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This paper presents a spatially resolved study of extraplanar diffuse ionized gas (eDIG) in the nearby galaxy pair NGC 3511 and NGC 3513. These galaxies are noteworthy because a quasar sightline passes near the minor axis of NGC 3511 and reveals a metal-rich Lyα absorber at nearly the same systemic velocity. Its projected location suggests that it may be sampling gas circulating through the disk—halo interface, motivating a detailed examination of ionized gas kinematics and excitation in both systems.

Using long-slit spectroscopy from Magellan/IMACS, we decompose nebular emission lines into narrow and broad velocity components, corresponding to planar disk emission and extraplanar gas. In NGC 3511, the broad component shows higher velocity dispersions ($\sim$24 km s$^{-1}$), elevated [N II]/Hα and [S II]/Hα ratios, and a clear rotational lag relative to the disk. These features are consistent with a vertically extended ionized layer supported by nonthermal motions and shaped by a reprocessed radiation field. Minor-axis spectra additionally reveal localized blueshifted features, indicating small outflows feeding the eDIG layer. The strength of DIG-like line ratios correlates with Hα equivalent width, suggesting that recent, bursty star formation plays a central role in setting the physical state of the extraplanar gas.

NGC 3513 exhibits a different pattern. Although a broad component is present, it reaches large velocity offsets (up to $\sim$130 km s$^{-1}$) without forming a coherent extraplanar layer. The spatial distribution is clumpy and line-ratio enhancements are weaker, pointing to localized, sub-escape outflows rather than a continuous eDIG structure.

A simple hydrostatic model for NGC 3511 shows that the turbulent pressure implied by the broad-component dispersions can support scale heights of $\sim$0.2—0.4 kpc, several times larger than the thermal value alone. This highlights the importance of nonthermal motions for the vertical structure of diffuse ionized gas. Taken together, the two galaxies provide insight into how low-mass disks loft, heat, and circulate ionized gas above their planes, and offer context for interpreting the enriched Lyα absorber detected along the nearby quasar sightline.