Rapid Follow-Up Observations of Tidal Disruption Events Discovered by Pan-STARRS1

This is the Phase II for my TOO to activate visits 1 & 2. I have added a dither pattern to the WFC3 observations. ----- Attempting Submission 1 (Sun Nov 01 20:10:10 GMT 2009) ----- ----- Attempting Submission 2 (Wed Sep 15 22:29:45 GMT 2010) ----- HST Phase II Proposal 12015 (apt_too_gezari.apt) successfully submitted. ----- Attempting Submission 3 (Wed Sep 15 22:40:15 GMT 2010) ----- HST Phase II Proposal 12015 (apt_too_gezari.apt) successfully submitted. ----- Attempting Submission 4 (Wed Sep 15 22:43:00 GMT 2010) ----- HST Phase II Proposal 12015 (apt_too_gezari_final.apt) successfully submitted. ----- Attempting Submission 5 (Thu Sep 16 13:55:50 GMT 2010) ----- Rapid Follow-Up Observations of Tidal Disruption Events Discovered by Pan-STARRS1 We propose for rapid follow-up Chandra TOO ACIS-S observations and HST/COS NUV imaging and FUV low-resolution spectroscopy of 5 flares from the tidal disruption of stars by supermassive black holes discovered in the Pan-STARRS1 Medium Deep Survey. With TOO observations obtained within a month of the peak of the flare, and 5 months later, we aim to 1) constrain the flare's broadband SED and bolometric luminosity, 2) follow the decay of the flare and look for spectral evolution, and 3) place strong limits on the presence of a persistent AGN nucleus. Tidal disruption events provide a cosmic laboratory to study the physics of accretion onto black holes, and are a unique probe of the mass of black holes in the nuclei of distant galaxies.

We request 3 orbits with COS for NUV imaging and FUV low-resolution spectroscopy triggered at the same time as the initial \textsl{Chandra} TOO observation for each target, for a total of 15 orbits. Sensitive COS NUV imaging ($\lambda_{eff}=2032$ \AA) in the ACQ/IMAGE mode will measure the $NUV-g$ color of the flare, and confirm the spatial coincidence of the flare with the nucleus of the galaxy. COS low-resolution spectroscopy with the wide spectral range of the G140L grating ($1230 - 2050$\AA) will allow us to directly measure the nature of the flare UV continuum that we have previously inferred from \textsl{GALEX} broadband photometry, and look for the contribution of Ly$\alpha~\lambda$1216, C IV $\lambda$1550, and CIII] $\lambda$1909 emission lines that may result from the reprocessing of the photoionizing continuum. A TDE with $g < 22$ and $kT_{bb}>0.01$ keV, and a Galactic extinction of $E(B-V)=0.02$ with $z<0.2$ will require an NUV ACQ/IMAGE with $t_{exp}=120$ sec for a S/N $> 40$ (the S/N requirement for an acquisition image). A FUV G140L spectrum with a S/N $> 10$ per resolution element will require $t_{exp}=7600$ sec (Calculated using the COS ETC). Each target should be observed by COS with a response time of $21-30$ days, i.e. just above the rapid TOO activation limit for \textsl{HST}. The orbits should be structured as follows. Orbit 1: HST initial guide star, NUV ACQ/IMAGE with $t_{exp}=120$ sec and FUV G140L spectrum (TIME-TAG mode) with $t_{exp}=2000$ sec. Orbits 2 \& 3: HST reaquisition, FUV G140L spectrum (TIME-TAG mode) with $t_{exp}=2800$ sec. AGN/QUASARS 12 false 300.0 0.0 false false false false false false SUPPORTED GALAXY NUCLEUS J2000 00 00 0.0000 +00 00 0.00 J2000 GALAXY NUCLEUS Host galaxy has no evidence of an AGN, has a redshift < 0.2, and the flare has g < 22. Host galaxy has no evidence of an AGN, has a redshift < 0.2, and the flare has g < 22. COS/NUV Imaging No No MIRRORA COS/FUV Spectroscopic No No G140L 1230 COS/NUV Imaging No No MIRRORA COS/FUV Spectroscopic No No G140L 1230 COS/NUV Imaging No No MIRRORA COS/FUV Spectroscopic No No G140L 1230 POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 1

false

Timing link suitability includes constraints ([02 After 01 by 17.0 to 21.0 days]) The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. /Users/suvi/galex_ps1/belfast/OP-cache/apt_too_gezari_dither_uvis1-v01.xml 1284644142496 (Tic-Visit :proposal-id 12015 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "16-Sep-2010 09:35:42.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1154992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12015 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12015 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2864 :al-overhead-at-end 116 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 1 0 Timing link suitability includes constraints ([02 After 01 by 17.0 to 21.0 days]) The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. /Users/suvi/galex_ps1/belfast/OP-cache/apt_too_gezari_dither_uvis1_final-v02.xml 1284644095866 (Tic-Visit :proposal-id 12015 :visit-id "02" :proposal-version -1 :trans-version "20100505" :date "16-Sep-2010 09:34:55.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 252288 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12015 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12015 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2857 :al-overhead-at-end 0 :internal-dur-at-end 116 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12015 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2864 :al-overhead-at-end 0 :internal-dur-at-end 116 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12015 :visit-id "02" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2864 :al-overhead-at-end 0 :internal-dur-at-end 428 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 3 0 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. /Users/suvi/galex_ps1/belfast/OP-cache/apt_too_gezari_dither_uvis1_final-v03.xml 1284644173332 (Tic-Visit :proposal-id 12015 :visit-id "03" :proposal-version -1 :trans-version "20100505" :date "16-Sep-2010 09:36:13.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1154992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12015 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12015 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2664 :al-overhead-at-end 116 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3234 :pcs-gap 0 ) true 1 0 Target of Opportunity 1284644097726 /Users/suvi/galex_ps1/belfast/OP-cache/apt_too_gezari_dither_uvis1_final-v04.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12015 :visit-id "04" :proposal-version -1 :trans-version "20100505" :date "16-Sep-2010 09:34:57.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 252288 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12015 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12015 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2857 :al-overhead-at-end 0 :internal-dur-at-end 116 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3234 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12015 :visit-id "04" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2864 :al-overhead-at-end 0 :internal-dur-at-end 116 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3234 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12015 :visit-id "04" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2864 :al-overhead-at-end 0 :internal-dur-at-end 428 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3234 :pcs-gap 0 ) true 3 0 Target of Opportunity 1284644098521 /Users/suvi/galex_ps1/belfast/OP-cache/apt_too_gezari_dither_uvis1_final-v05.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12015 :visit-id "05" :proposal-version -1 :trans-version "20100505" :date "16-Sep-2010 09:34:58.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1154992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12015 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12015 :visit-id "05" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2864 :al-overhead-at-end 116 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3234 :pcs-gap 0 ) true 1 0 Target of Opportunity