Resubmission with increased HRC exposure times for visits 13 and 15 ----- Submission 1 (Thu May 12 01:01:43 GMT 2005) ----- ----- Submission 2 (Fri May 27 18:04:27 GMT 2005) ----- ----- Submission 3 (Fri Jul 08 21:12:48 GMT 2005) ----- ----- Submission 4 (Wed Jul 13 17:37:07 GMT 2005) ----- ----- Submission 5 (Wed Aug 17 15:35:01 GMT 2005) ----- Assigned ID: 231 ----- Submission 1 (Fri Jan 21 16:53:40 GMT 2005) ----- ULX counterparts: the key to finding intermediate-mass black holes The origin and formation mechanism for supermassive black holes (SMBHs) found in the centres of most, if not all, galaxies remains one of the outstanding questions in astrophysics. Most scenarios involve the presence of massive black holes in the early universe, formed by the collapse of primordial Population III stars. It is predicted that a relic of this population could still be present in galactic halos in the current epoch, possessing masses from a few hundred times solar mass upwards. However, to date no CONCLUSIVE evidence for such a class of "intermediate-mass" black holes has been found. The most likely current candidates are the ultraluminous X-ray sources (ULXs), which show tantalising evidence for IMBHs (e.g. the extreme X-ray luminosities and low disk temperatures expected from accreting IMBHs). We propose to address this issue by identifying optical counterparts for six of the nearest ULXs. We will use this programme as a pathfinder for future radial velocity measurements, which will allow the orbital parameters and hence the first undisputed mass constraints for these systems to be determined.
For each of our six targets we will obtain two orbits of imaging. One of these will utilize the ACS/WFC for B (F435W) and V-R (F606W) observations (note that we choose F606W over F555W, which is closer in coverage to the classic V filter, due to its superior throughput which allows far higher sensitivity observations). We will perform two exposures in each of the filters to enable cosmic ray rejection, these exposures will have a typical length of ~500s. This will allow us to reach 5-sigma magnitude limits of F435W = 26.6 and F606W = 27.2 corresponding to$M_B =-2.6 and Mv = -2.0 at a distance of 7 Mpc (the mean distance of our sample), and is sufficiently deep to observe B-stars on the main sequence. Our second orbit will use the ACS/HRC to obtain U-band (F330W) observations of the same targets. We will perform four exposures within the orbit utilising a small dither pattern to aid with cosmic-ray rejection and PSF recovery via the drizzle algorithm. The depth of the subsequently combined image will be F330W = 24.5 (equivalent to a B star with F606W = 26). This will provide a second colour (U-B), allowing the spectral type of any faint blue stellar companions to be constrained. The use of the HRC will also utilise the unmatched PSF of HST to its maximum effect, providing the highest resolution observations available to resolve potentially complex regions of the underlying galaxy. To precisely position our ULXs onto the celestial frame of the HST images we will perform relative astrometry between the ACS/WFC and Chandra frames. The increased field of view of ACS/WFC with respect to WFPC2 means that we can expect a larger number of X-ray sources to fall within our field of view. In the event that insufficient sources are unambigously identified on the ACS frame we will use ground-based images as intermediates to aid the alignment. We will align the ACS/HRC field to that of the WFC utilising common point source in each field. Via this method we will be able to recover the positions of ULXs on our ACS frames to positional accuracies of < 0."3. GALAXIES 12 false 20 0.0 false 0 false false false false SUPPORTED UNIDENTIFIED ACCRETION DISK X-RAY EMITTER fx = 7.1e-13 erg/cm^2/s (0.5 - 2 keV) J2000 07 36 25.5500 +65 35 40.00 J2000 UNIDENTIFIED ACCRETION DISK X-RAY EMITTER fx = 1.8e-13 erg/cm^2/s (0.5 - 2 keV) J2000 12 30 30.5600 +41 41 42.30 J2000 UNIDENTIFIED ACCRETION DISK X-RAY EMITTER fx = 7.3e-13 erg/cm^2/s (0.5 - 2 keV) J2000 13 15 19.5000 +42 03 2.20 J2000 UNIDENTIFIED ACCRETION DISK X-RAY EMITTER We would prefer to have the Chandra observation of this source taken (and analysed) before these observations are performed, so that we have the most accurate X-ray position of the ULX to point HST at. However, as the X-ray position is already good to < 5 arcsec, this is not an absolute necessity. fx = 3.8e-13 erg/cm^2/s (0.5 - 2 keV) J2000 13 37 20.1000 -29 53 46.00 J2000 UNIDENTIFIED ACCRETION DISK X-RAY EMITTER J2000 00 00 0.0000 +00 00 0.00 J2000 UNIDENTIFIED ACCRETION DISK X-RAY EMITTER J2000 00 00 0.0000 +00 00 0.00 J2000 ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F435W ACS/HRC Imaging No No F330W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F435W ACS/HRC Imaging No No F330W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F435W ACS/HRC Imaging No No F330W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F435W ACS/HRC Imaging No No F330W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F435W ACS/HRC Imaging No No F330W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F435W ACS/HRC Imaging No No F330W POS-TARG DITHER 0.15 LINE false false 2 34.13 ACS-WFC-DITHER-LINE 1 false POS-TARG DITHER 0.15 LINE 0.098 false false 63.5 4 19.89 ACS-HRC-DITHER-BOX 2 false /private/tmp/OPVisit25433.xml (Tic-Visit :proposal-id 10579 :visit-id "03" :proposal-version -1 :trans-version "20050323" :date "17-Aug-2005 16:22:53.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 2281984 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10579 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 10579 :visit-id "03" :obset-id "A3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10579 :visit-id "03" :orbit-number 1 :pcs-time 367 :si-vis-utilization 3245 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3614 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10579 :visit-id "03" :orbit-number 2 :pcs-time 367 :si-vis-utilization 3242 :al-overhead-at-end 0 :internal-dur-at-end 351 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3614 :pcs-gap 0 ) true 2 0 /private/tmp/OPVisit25434.xml (Tic-Visit :proposal-id 10579 :visit-id "07" :proposal-version -1 :trans-version "20050323" :date "17-Aug-2005 16:23:48.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 2281984 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10579 :visit-id "07" :obset-id "07" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 10579 :visit-id "07" :obset-id "A7" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10579 :visit-id "07" :orbit-number 1 :pcs-time 367 :si-vis-utilization 2981 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3351 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10579 :visit-id "07" :orbit-number 2 :pcs-time 367 :si-vis-utilization 2982 :al-overhead-at-end 0 :internal-dur-at-end 351 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3351 :pcs-gap 0 ) true 2 0 /private/tmp/OPVisit25435.xml (Tic-Visit :proposal-id 10579 :visit-id "09" :proposal-version -1 :trans-version "20050323" :date "17-Aug-2005 16:24:14.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1136896 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10579 :visit-id "09" :obset-id "09" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10579 :visit-id "09" :orbit-number 1 :pcs-time 367 :si-vis-utilization 2981 :al-overhead-at-end 0 :internal-dur-at-end 349 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3351 :pcs-gap 0 ) true 1 0 /private/tmp/OPVisit25436.xml (Tic-Visit :proposal-id 10579 :visit-id "10" :proposal-version -1 :trans-version "20050323" :date "17-Aug-2005 16:24:25.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1145088 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10579 :visit-id "10" :obset-id "10" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10579 :visit-id "10" :orbit-number 1 :pcs-time 367 :si-vis-utilization 2982 :al-overhead-at-end 0 :internal-dur-at-end 351 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3351 :pcs-gap 0 ) true 1 0 /private/tmp/OPVisit25437.xml (Tic-Visit :proposal-id 10579 :visit-id "11" :proposal-version -1 :trans-version "20050323" :date "17-Aug-2005 16:24:42.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 2281984 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10579 :visit-id "11" :obset-id "11" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 10579 :visit-id "11" :obset-id "A1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10579 :visit-id "11" :orbit-number 1 :pcs-time 367 :si-vis-utilization 2749 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10579 :visit-id "11" :orbit-number 2 :pcs-time 367 :si-vis-utilization 2898 :al-overhead-at-end 0 :internal-dur-at-end 351 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) true 2 0 We would prefer to have the Chandra observation of this source taken (and analysed) before these observations are performed, so that we have the most accurate X-ray position of the ULX to point HST at. However, as the X-ray position is already good to < 5 arcsec, this is not an absolute necessity. /Users/levan/OP-cache/10579-aug-v13.xml (Tic-Visit :proposal-id 10579 :visit-id "13" :proposal-version -1 :trans-version "20050323" :date "17-Aug-2005 16:09:52.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 2281984 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10579 :visit-id "13" :obset-id "13" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 10579 :visit-id "13" :obset-id "A3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10579 :visit-id "13" :orbit-number 1 :pcs-time 367 :si-vis-utilization 3245 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3614 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10579 :visit-id "13" :orbit-number 2 :pcs-time 367 :si-vis-utilization 3230 :al-overhead-at-end 0 :internal-dur-at-end 351 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3614 :pcs-gap 0 ) true 2 0 /private/tmp/OPVisit31188.xml /Users/levan/OP-cache/10579-aug-v15.xml (Tic-Visit :proposal-id 10579 :visit-id "15" :proposal-version -1 :trans-version "20050323" :date "17-Aug-2005 16:11:09.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 2281984 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10579 :visit-id "15" :obset-id "15" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 10579 :visit-id "15" :obset-id "A5" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10579 :visit-id "15" :orbit-number 1 :pcs-time 367 :si-vis-utilization 3245 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3614 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10579 :visit-id "15" :orbit-number 2 :pcs-time 367 :si-vis-utilization 3230 :al-overhead-at-end 0 :internal-dur-at-end 351 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3614 :pcs-gap 0 ) true 2 0 /private/tmp/OPVisit31190.xml