Superwinds associated with the triggering of quasars are of current interest because such feedback effects may be connected with the initial formation of the black-hole-mass/bulge mass correlation. In the z = 0.369 compact-steep-spectrum quasar 3C48, ground-based IFU observations show the presence of a high-velocity, wide-solid-angle outflow of gas, apparently connected with the recent formation of the radio jet. The total mass of gas in this outflow is at least 10^9 solar masses, but it could be well over 10^10 solar masses (i.e., similar to or greater than the total interstellar mass of the Milky Way) if most of the gas has densities like those seen in other quasar extended emission regions. To determine the physical state and energetics of the gas in the outflow, we request (1) high-spatial-resolution spectroscopy over a wide spectral range, including the near UV, and (2) medium-resolution spectroscopy of the strong [O III] 5007 line, which, when combined with unpublished archival data, will allow complete coverage of the velocity field of the high-velocity gas in the inner region.

The proposed low-resolution observations use a 0.2" slit at a nominal position angle of 0 deg centered on the quasar and covering the brightest region of the high-velocity emission ~ 0.2" to the north. While the narrow-band LRF WFPC-2 image shows the brightness peak slightly west of north, this position is influenced by the filter response function and the variation of velocity with position. From our GMOS IFU data shown in Fig. 3, we conclude that the best compromise position angle for the slit is due north. We use 3 of the low-resolution modes to cover rest-frame wavelengths from below Ly-alpha to beyond H-alpha and [S II] 6716,6731: the G230L grating with the NUV-MAMA detector, and the G430L and G750L gratings with the CCD. From archival WFPC2 linear-ramp-filter imaging, we have estimated the [O III] 5007 flux in the resolved emission peak ~ 0.2" north of the quasar to be ~ 10^-14 ergs cm^-2 s^-1. For the optical lines, we use measurements of an extended emission region in the quasar 4C37.43 (Stockton et al. 2002) to estimate relative line strengths. For the UV lines, we use models from the same paper that fit the optical spectrum well to predict the strengths. The estimates are likely to be somewhat conservative, as most of the weaker diagnostic lines are from species requiring similar or higher ionization potentials than [O III], and our best guess is that the gas in the region we are observing in 3C48 will likely have a higher ionization parameter than that in 4C37.43, since it is at a considerably smaller projected distance from the quasar. The lines that set the required exposure times are He II 1640 and C III] 1909 in the UV, and [Ne V] 3425, [O III] 4363, and He II 4686 in the optical region. Because we need to fit profiles to separate out the high-velocity emission from extended emission at the systemic velocity, we need a S/N > 10 per resolution element in these weaker lines. The weaker lines in the optical have typical predicted fluxes of ~ 2?10^-16 ergs cm^-2 s^-1; those in the UV have ~ 10^-15 ergs cm^-2 s^-1. However, the STIS ETC gives exposures to reach a S/N ~ 10 of ~ 4500 s in all cases. We therefore request 2 orbits for each of our grating/detector configurations, for a total of 6 orbits for the low-spectral-resolution observations. For the high-resolution observations of the [O III] 5007 region, we request the same exposures as the archival spectra we are matching, which we have found to give satisfactory S/N for profile fitting: 2 orbits for each of the 2 slit positions, for a total of 4 orbits. Thus, we are requesting 10 orbits in all. There have been several previous HST spectroscopic investigations of 3C48 (6707, 8299, 9280, and our own 9365), but none of these duplicate the proposed observations. Those from GO-8299 cover some of the region we are interested in, but these have a spectral range that includes only small regions around the H-beta-[O III] 5007 region and the H-alpha region. As described above, 2 of our slit positions will obtain similar observations of the H-beta-[O III] 5007 region in spatial gaps not covered by this program. The remaining programs do not have the required spatial coverage, do not cover spectral regions of interest, or both. AGN/QUASARS 12 false 0.0 0.0 false false false false false false SUPPORTED GALAXY EJECTA EMISSION LINE NEBULA WIND This object was generated by the targetselector and retrieved from the NED database. J2000 01 37 41.3000 +33 09 35.00 J2000 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G750M 6768 POS-TARG DITHER 1.008 Meant to give 42 pixels between points. LINE false true 5 90.0 STIS-ALONG-SLIT 1 false POS-TARG DITHER 1.00 LINE false true 4 90.0 STIS-ALONG-SLIT 2 false POS-TARG MOSAIC DITHER 4 0.3 STIS-ALONG-SLIT false true 1.0 2 0.0 POS-TARG STIS-PERP-TO-SLIT 90.0 3 true POS-TARG DITHER 1 LINE false true 2 90.0 STIS-ALONG-SLIT 4 false The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. 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