I have added the new 3 targets and added FLASH observations for all F438W observations.-1163069392----- Attempting Submission 2 (Tue Nov 19 22:38:24 GMT 2013) -----A Pilot Search for Spatially Offset AGN in Galaxy Merger RemnantsWe request Chandra/ACIS-S observations and HST imaging for a pilot study of 8 galaxies whose AGN emission lines are offset in velocity from systemic. These are candidates for offset AGN, which occur when one of the two supermassive black holes in a galaxy merger is active. We have carefully constructed our sample to remove cases where gas kinematics produce the velocity offsets, but Chandra and HST observations are necessary to confirm offset AGN as the AGN that are spatially offset from the primary galaxy centers. With the observations proposed here, we will carry out the first systematic search for offset AGN. We will use the results of this search to study the circumstances for triggering offset AGN, and to inform future searches for offset AGN.We request 8 HST orbits of WFC3 B, V, and H observations, which will reveal 1) stellar nuclei coincident with the AGN, where the relative brightnesses of the stellar nuclei will constrain the mass ratio of the galaxy merger that produced the offset AGN; 2) spatially extended [O III] 5007 emission suggesting AGN outflows as the source of the velocity offsets; 3) low surface-brightness features such as tidal tails that are signatures of recent merging activity; and 4) host galaxy stellar populations, which may reveal recent star formation triggered by a merger. HST is the only telescope with the ideal wavelength range and spatial resolution to both obtain the colors necessary for stellar population modeling and image small-scale tidal features and ~100 pc offsets of stellar nuclei at our redshift range (the WFC3 IR and UVIS pixel scales are 0.13" and 0.04", which correspond to 180 pc and 50 pc at the median redshift of our targets).
We require multiple filters in order to disentangle, both spectrally and spatially, variations in stellar populations. We bracket the stellar populations with an F438W (B) image that avoids Hbeta emission and is sensitive to young stars and an F160W (broad H) image that will be sensitive to old stellar populations and avoid dust. In between, we use F606W (broad V) to provide a red filter and to image any spatially extended [O III] 5007 emission that may point to outflows as the source of the velocity offsets. WFC3 is the camera of choice, as it will enable us to cover the entire wavelength range with the highest sensitivity and finest pixel scale.
We request one orbit (~51 min) per target, which will provide the exposure times needed to reveal merger-remnant signatures of the host galaxies. Using the WFC3 IR and UVIS Exposure Time Calculators, we estimated our science exposure times for the stellar nuclei accompanying the AGN by 1) the assumption that the companion stellar nucleus is two magnitudes fainter than the total primary galaxy (as in Comerford et al. 2009); 2) the assumption that the mass ratio, which is unknown, could be as small as 10:1; and 3) the requirement that each stellar nucleus be detected at a signal-to-noise ratio >20. These exposure times also ensure signal-to-noise ratios ~5 in a 9 x 9 pixel box for typical host galaxy tidal features with an I_{AB} surface brightness of 24 mag/arcsec^2 (see, e.g., Forbes et al. 2003). They will also enable robust measurements of the host galaxy stellar populations.
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In the UVIS, we will use a three-point dither pattern to facilitate cosmic-ray and hot-pixel removal. In the IR, we will use the WFC3-IR-DITHER-BOX in order to properly sample the PSF. We will use subarrays (1k x 1k for UVIS and IRSUB512 for IR) to avoid buffer dumps, and our readout mode (STEP25 with NSAMP=6) will prevent saturation.DefaultfalsefalsefalsefalsefalseSUPPORTEDGALAXYSEYFERTJ2000J2000GALAXYSEYFERTJ2000J2000GALAXYSEYFERTJ2000J2000GALAXYSEYFERTJ2000J2000GALAXYSEYFERTJ2000J2000GALAXYSEYFERTJ2000GALAXYSEYFERTJ2000GALAXYSEYFERTJ2000WFC3/IRImagingNoNoF160WWFC3/UVISImagingNoNoF438WWFC3/UVISImagingNoNoF606WWFC3/IRImagingNoNoF160WWFC3/UVISImagingNoNoF438WWFC3/UVISImagingNoNoF606WWFC3/IRImagingNoNoF160WWFC3/UVISImagingNoNoF438WWFC3/UVISImagingNoNoF606WWFC3/IRImagingNoNoF160WWFC3/UVISImagingNoNoF438WWFC3/UVISImagingNoNoF606WWFC3/IRImagingNoNoF160WWFC3/UVISImagingNoNoF438WWFC3/UVISImagingNoNoF606WWFC3/IRImagingNoNoF160WWFC3/UVISImagingNoNoF438WWFC3/UVISImagingNoNoF606WWFC3/IRImagingNoNoF160WWFC3/UVISImagingNoNoF438WWFC3/UVISImagingNoNoF606WWFC3/IRImagingNoNoF160WWFC3/UVISImagingNoNoF438WWFC3/UVISImagingNoNoF606WPOS-TARGDITHER0.135LINEfalsefalse346.84WFC3-UVIS-DITHER-LINE-3PT1falsePOS-TARGDITHER0.572LINE0.365falsefalse74.653418.528WFC3-IR-DITHER-BOX-MIN2falseThe scheduling data was generated by CASM 21.2.CASM was run in Phase II mode./Users/julie/Desktop/OP-cache/13513_new-v01.xml(Tic-Visit
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