12260( 4) - 27-Jun-2011 12:04:50 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12260 Version: 4 Check-in Time: 27-Jun-2011 12:04:50 STScI Edit Number: 0 Title Probing Intermediate Ionization Gas in the Perseus and Virgo Clusters ------------------------------------------------------------------------------------ Type Cycle GO 18 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Roderick M. Johnstone University of Cambridge CoI: Prof. Andrew C. Fabian University of Cambridge N ------------------------------------------------------------------------------------ Abstract The physics of the evolution of X-ray emitting gas in the cores of clusters is now known to be much more complex than the simple cooling model. In order to understand how the observed molecular/atomic and keV components interact we need to probe the full range of gas phases between these components. We therefore propose deep ultraviolet spectra of the active nucleii in NGC1275 and M87, the central galaxies in the Perseus and Virgo clusters. Discovery of absorption lines from highly ionized species such as CIV and SiIV will provide a sensitive diagnostic of this crucial intermediate phase of the intracluster medium that is not accessible in any other way. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose high resolution spectroscopy of the active nucleii in NCG 1275 and M87 covering the absorption doublets of SiIV 1400, CIV 1550 using COS. HST is required because these lines lie in the ultraviolet part of the spectrum. COS is the instrument selected as it has the best sensitivity for these observations. We aim to reach a sensitivity at SiIV and CIV in equivalent width and column density terms that are at least a factor of ten better than our initial work on NGC1275 with FOS (Johnstone et al 1995). That work set a 3sigma equivalent width limit of 300mA on the absorption from the CIV doublet corresponding to a column density of 1 ? 2 ? 10^14cm?2 in the C3+ ion. We have used the COS ETC to estimate exposure times. With the G160M gating set to a central wavelength of 1600A we can observe the SiIV and CIV lines simultaneously. Assuming a continuum flux density of 10^?15erg cm^?2 s^?1 ^A?1, (appropriate for NGC1275; M87 is about a factor of two brighter; Pogge et al 2000) a flat continuum in F(lambda) and nominal background levels then in a 3 orbit visit (total of 8600 s on source) a signal-to-noise ratio per resolution element of 12260( 4) - 27-Jun-2011 12:04:50 - [ 2] S/N=9.5 and S/N=6.8 is attained at the (redshifted) wavelengths of SiIV and CIV respectively. Using a resolution element of 6 pixels or 73mA this translates to an equivalent width uncertainty of 7.7mA and 10.7mA respectively, or 3sigma upper limits of 23 and 32 mA. The VPGUESS program (http://www.eso.org/ jliske/vpguess/) is then used to convert these equivalent width values to uncertainties in ionic column densities, yielding 3 detection upper limits of 3 ? 10^12cm?2 and and 8 ? 10^12cm?2 for SiIV and CIV respectively. These column densities are on the linear part of the curve of growth and are therefore not dependent on line width for reasonable values of thermal broadening. Uncertainties for M87 will be a factor of sqrt(2) tighter. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 12260( 4) - 27-Jun-2011 12:04:50 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 2 M87-NUCLEUS GALAXY, BCM, ELLIPTICAL RA=12H30M49.4230S +/- 0.1", J2000 V = 1307 V = 11.4 +/- 2 2 +/- 0.4 DEC=+12D23'28.04" +/- 0.1" e-15erg/cm^2/s/A at 1600A Reference Frame: ICRS Comments: Position is from VLBI from Ma et al 1998, AJ 116, 516 Flux in the M87 nucleus at ~2700A (ACS/F250W) =0.14mJy (~7e-16 erg/sm/sm/s/A) on 2006 Dec 30 published by Madrid 2009, ApJ 137, 3864 is used for the NUV acquisition exposure time calculation. ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC1275-NUCL GALAXY, BCM, ELLIPTICAL RA=03H19M48.1600S +/- 0.2", J2000 V = 13 +/- 2 1+/-0.2 e-15 erg/cm/cm/s/A EUS DEC=+41D30'42.11" +/- 0.2" at 1600A, 3.2e-15 erg/cm/cm/s/A at 2300A Reference Frame: ICRS Comments: Position is from VLBI from Ma et al 1998, AJ 116, 516 Flux at 1600 (FOS 0.21x1.23 aperture) from Johnstone + Fabian 1995 MNRAS 273, 625. Flux at 2300A confirmed from small extrapolation of preview data for HST dataset O62O05010 (2000-08-18) STIS 52x0.2. That spectrum is largely in agreement with F320W columns in Table 5 of Zirbel + Baum 1998, ApJ, 114, 177 when only point source component is taken into account. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 0.0 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 6 OFFSET-FROM- CLUSTER OF GALAXIES, RA-OFF=-0.027S +/- 0.001S, J2000 V = 35.0 M87-NUCLEUS MULTIPLE NUCLEI DEC-OFF=+0.175" +/- 0.001", FROM 2 Reference Frame: ICRS Comments: Offset to centre COS aperture mid-way betweenM87 nucleus and HST-1. These offsets assume that th acquisition picked up M87 nucleus as the brigher of the two soures. If HST-1 is seen to be brighter than M87 nucleus in the quiescence check observation there offsets need to be changed. ------------------------------------------------------------------------------------------------------------------------------------ 12260( 4) - 27-Jun-2011 12:04:50 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: NGC1275 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC1275-NUC COS/NUV ACQ/IMA PSA MIRRORB 1 45 S LEUS GE ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC1275-NUC COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=2529, FP-POS=1 1 2529 S LEUS G ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC1275-NUC COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=1698, FP-POS=1 1 1698 S LEUS G ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC1275-NUC COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=1172, FP-POS=2 1 1172 S LEUS G ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC1275-NUC COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=3055, FP-POS=2 1 3055 S LEUS G ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC1275-NUCLEUS 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A GE NGC1275-NUCLEUS 2 COS/FUV TIME-TA PSA G160M 1600 none none none none 1 N/A G NGC1275-NUCLEUS 3 COS/FUV TIME-TA PSA G160M 1600 none none none none 2 N/A G NGC1275-NUCLEUS 4 COS/FUV TIME-TA PSA G160M 1600 none none none none 2 N/A G NGC1275-NUCLEUS 5 COS/FUV TIME-TA PSA G160M 1600 none none none none 3 N/A G 12260( 4) - 27-Jun-2011 12:04:50 - [ 5] Visit: 02 Visit Requirements: ORIENT 220D TO 280 D; ORIENT 40D TO 100 D On Hold Comments: Additional Comments: NGC4486 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M87-NUCLEUS COS/NUV ACQ/IMA PSA MIRRORA 1 12 S GE ------------------------------------------------------------------------------------------------------------------------------------ 2 OFFSET-FROM COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=2528, FP-POS=3 1 2528 S -M87-NUCLEU G S ------------------------------------------------------------------------------------------------------------------------------------ 3 OFFSET-FROM COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=1602, FP-POS=3 1 1602 S -M87-NUCLEU G S ------------------------------------------------------------------------------------------------------------------------------------ 4 OFFSET-FROM COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=1172, FP-POS=4 1 1172 S -M87-NUCLEU G S ------------------------------------------------------------------------------------------------------------------------------------ 5 OFFSET-FROM COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=2959, FP-POS=4 1 2959 S -M87-NUCLEU G S ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ M87-NUCLEUS 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE OFFSET-FROM-M87-NUC 2 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 N/A LEUS G OFFSET-FROM-M87-NUC 3 COS/FUV TIME-TA PSA G160M 1589 none none none none 2 N/A LEUS G OFFSET-FROM-M87-NUC 4 COS/FUV TIME-TA PSA G160M 1589 none none none none 2 N/A LEUS G OFFSET-FROM-M87-NUC 5 COS/FUV TIME-TA PSA G160M 1589 none none none none 3 N/A LEUS G 12260( 4) - 27-Jun-2011 12:04:50 - [ 6] Summary Form for Proposal 12260 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1172, BUFFER-TIME=1602, BUFFER-TIME=1698, BUFFER-TIME=2528, BUFFER-TIME=2529, BUFFER-TIME=2959, BUFFER-TIME=3055, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 220D TO 280 D, ORIENT 40D TO 100 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G160M, MIRRORA, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names M87-NUCLEUS, NGC1275-NUCLEUS, OFFSET-FROM-M87-NUCLEUS ------------------------------------------------------------------------------------------------------------------------------------