EXTENDED SOFT-X-RAY EMISSION IN SEYFERT-GALAXIES - ROSAT HRI OBSERVATIONS OF NGC-3516, NGC-4151, AND MARKARIAN-3

We have used the ROSAT High Resolution Imager (HRI) to examine the dis tribution of soft X-rays in three nearby Seyfert galaxies with similar to 4''-5'' FWHM spatial resolution. A feature of our analysis is an a ttempt to remove errors in the aspect solution using a method develope d by one of us (J. M.). NGC 4151 shows resolved X-ray emission that is spatially correlated with the optical extended narrow-line region (EN LR), confirming the results obtained with the Einstein HRI by Elvis, B riel, & Henry. Image deconvolutions allow us to trace the extended X-r ays along a position angle of similar to 50 degrees/230 degrees as far as similar to 1.5 kpc southwest and similar to 0.5 kpc northeast of t he nucleus (assuming a distance of 20 Mpc with H-0 = 50 km s(-1) Mpc(- 1)). When a point source is subtracted from the nucleus of NGC 4151, t he extended, bipolar X-rays peak in brightness similar to 425 pc south west of the nucleus and similar to 280 pc northeast of the nucleus. Th e extended emission accounts for at least 31% of the total 0.1-2 keV R OSAT HRI flux (19% from the southwest quadrant, 12% from the northeast and constitutes roughly half of the total soft X-ray excess emission observed with other X-ray detectors. The soft X-ray excess in NGC 4151 has been modeled recently as containing both variable and constant fl ux components. We suggest that the constant flux component of the soft excess emission originates in the spatially extended regions we have resolved. If the extended X-rays result from electron-scattering of nu clear X-rays, the central source must emit anisotropically, and prefer entially toward the extended X-rays and the ENLR. Alternatively, the e xtended X-rays may represent thermal emission from a hot (T similar to 10(7) K), outflowing wind which is in rough pressure equilibrium with the optical narrow-line-emitting clouds observed over the same spatia l scale. NGC 3516 is elongated along a position angle of similar to 40 degrees/220 degrees, similar to the direction of the Z-shaped narrow- line region. However, the azimuthally averaged radial brightness profi le inside a radius of 10'' is not distinguishable from a calibration p oint source. Much or all of the elongation may result from residual er rors in the aspect solution, although an extended component associated with the ENLR is possible. Mrk 3 is very faint in our HRI image and i s probably spatially unresolved. We detect the faint X-ray source simi lar to 2' west of the Mrk 3 nucleus previously found by Turner, Urry, & Mushotzky. It is not known whether this companion is physically asso ciated with Mrk 3 although it does lie along a direction that is withi n similar or equal to 1 degrees of the axis of the 2'' nuclear radio j et. We also detected the BL Lac object BL 1207 + 39 similar to 5' nort h-northwest of NGC 4151. This object appears spatially unresolved, but some excess X-ray emission may be observed in the azimuthally average d radial brightness profile of BL 1207+39 between radii of 10'' and 30 '' when compared to a calibration source. A much deeper image is neces sary to confirm this result.