16422( 5) - 16-Nov-2020 14:27:01 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16422 Version: 5 Check-in Time: 16-Nov-2020 14:27:01 STScI Edit Number: 0 Title Probing Super-Eddington Outflows via Accreting Galactic BeXRBs ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Mark Reynolds University of Michigan Y CoI: Mr. Jakob van den Eijnden Universiteit van Amsterdam N CoI: Dr. Nathalie Degenaar Universiteit van Amsterdam N CoI: Dr. Jon Matthew Miller University of Michigan N CoI: Dr. Dominic Walton University of Cambridge N ------------------------------------------------------------------------------------ Abstract Observations of the population of ultra luminous X-ray sources has revealed that at least a subset of this group contains a neutron star primary. Thus, dramatically demonstrating the viability of super-Eddington accretion for this source class. However, the physics of these super-Eddington accretion flows are poorly understood with the sources typically lying at Mpc distances. The population of Galactic Be/X-ray binaries (BeXRBs) are known to have giant outbursts that enter the super-Eddington regime and promise the opportunity to learn much about this mode of accretion. Herein, we propose to obtain simultaneous high resolution X-ray, UV and radio spectroscopy of the next bright Galactic BeXRB to enter a giant outburst when the neutron star will be accreting in the super-Eddington regime. ------------------------------------------------------------------------------------ Observations Description ------------------------ Studies of giant outbursts of other BeXRBs are highly warranted to determine that winds and jets indeed occur simultaneously in the super-Eddington regime. We note that ULXs are too distant to detect a compact radio jet, so determining the co-existence of winds and jets at highly super-Eddington accretion rates can ONLY be achieved with Galactic BeXRBs, as we aim to target with this proposal. To be able to confirm the presence of both winds and jets in the super-Eddington regime, we therefore proposed for and were granted (quasi-simultaneous) Chandra/HETGS, HST/STIS and JVLA observations of the next giant outburst of a BeXRB. In a BeXRB accreting a super Eddington luminosities, we expect the UV emission to evolve when the accretion envelope develops and shields the outer disk from the inner X-ray emitting region, e.g., Shakura & Sunyaev (1973). In this regime we might expect the UV emission to be dominated by the re-reprocessing component detected in soft X-rays. The high S/N and spectral resolution of STIS will be key here as the kinematics of the accretion inflow and wind will be encoded in the spectral lines. Obtaining observational evidence for wind outflows in ULXs is highly challenging due to the high absorption and distance to these systems. However, low resolution HST/ACS prism spectroscopy has had some limited success and demonstrated the presence of a complex highly ionized outflow at these accretion rates (e.g. M81 X-1, Bregman et al., 2012). 16422( 5) - 16-Nov-2020 14:27:01 - [ 2] We are requesting observations with STIS with the MAMA detector and the E140M grating, which will provide wavelength coverage from 1150 - 1800 Ang . The high dispersion provided by this grating will ensure the safety of the MAMA detector as these sources can be very bright (> 0.06 Jy; lambda_c ~ 2200Ang). In the event of a fainter UV counterpart, a lower resolution grating will be utilized. Accurate flux estimates will be provided by Swift/UVOT observations in support of this program. GYRO MODE: As our program is a joint ToO w/ Chandra & JVLA, reduced gyro mode observations would reduce our ability to observe a quasi-random outburst from an unknown source (though likely in Galactic plane). Fingers crossed! ------------------------------------------------------------------------------------ 16422( 5) - 16-Nov-2020 14:27:01 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 1A0535+262 STAR, ACCRETION DISK, RA=05H38M54.5749S, J2000 V = 9.39 BE, X-RAY TRANSIENT DEC=+26D18'56.84" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Coords are ICRS from GAIA DR2. Observation awarded through CXO program. Observation to occur quasi-simultaneously with CXO (+\- 1 day). The source is currently undergoing a large type-II outburst. The program has been triggered. Further trigger details should come via CXO. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -4.611219896513134E-5 -0.002803000097628683 0.4424e-3 ------------------------------------------------------------------------------------------------------------------------------------ 16422( 5) - 16-Nov-2020 14:27:01 - [ 4] Visit: 02 (ToO (1A 0535+262)) Visit Requirements: SCHED 100% On Hold Comments: Additional Comments: Source is bright (<10 Vega or >50mJy) at 2200 Ang Template for original proopsal, trigger target is below. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 1A0535+262 STIS/CCD ACQ F25ND3 MIRROR 1 1.0 S (1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 1A0535+262 STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 996 S (996 -MAMA S) Comments: Grating changed to E140M as the source is bright and has measured Swift/UVOT fluxes during this outburst of >50mJy @2200 Ang. ------------------------------------------------------------------------------------------------------------------------------------ 3 1A0535+262 STIS/FUV ACCUM 0.2X0.2 E140M 1425 WAVECAL=NO 1 990 S (990 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 4 WAVE STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 DEF (0 S) -MAMA ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 1A0535+262 1 STIS/CCD ACQ F25ND3 MIRROR none none none none 1 N/A 1A0535+262 2 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA 1A0535+262 3 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA WAVE 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA 16422( 5) - 16-Nov-2020 14:27:01 - [ 5] Summary Form for Proposal 16422 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 0.2X0.2, F25ND3 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 100% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements E140M, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names 1A0535+262, WAVE ------------------------------------------------------------------------------------------------------------------------------------