For G160M observations, please consult Chapter 9 of the COS Instrument Handbook to estimate overheads and the number of exposures per orbit, and consequently the correct lifetime position. Use of LP4 with G160M requires justification in the "Special Requirements" section of the Phase I PDF. Use of the default LP6 with G160M requires no justification. Proposals can be submitted with the warning present.0Assigned ID: 6684
----- Attempting Submission 1 (Thu Apr 10 20:52:03 GMT 2025) -----
HST Phase I Proposal 6684 successfully submitted.
Receipt: # 6684-1
----- Attempting Submission 2 (Thu Apr 10 20:53:44 GMT 2025) -----
HST Phase I Proposal 6684 successfully submitted.
Receipt: # 6684-2We will use LP6 and require no speical accommodation.0----- Attempting Submission 1 (Tue Aug 05 19:54:38 GMT 2025) -----
----- Attempting Submission 2 (Wed Jan 14 03:31:20 GMT 2026) -----Confirming and Characterizing a Fast, Cool Inflow Toward a Luminous Quasar at z = 0.78We propose HST COS+STIS observations of J0233-0455, a z=0.78 quasar exhibiting redshifted, inflowing Mg II absorption at +800 km/s, to study the elusive process of gas accretion onto supermassive black holes (SMBHs). While AGN outflows are well-documented, direct observations of gas inflows that fuel SMBHs remain extremely rare. Our target was identified through a systematic search for quasars with redshifted absorption, similar to a recent inflow discovered along with a filamentary nebula. As the brightest of the ten quasars found exhibiting the redshifted Mg II absorption, J0233-0455 is singularly suitable as a pilot target for the detailed UV spectroscopy we propose. The proposed UV spectroscopy will target key transitions including Ly-alpha, Ly-beta, the Lyman limit, C II, C IV, and O VI, allowing us to characterize the physical properties, ionization state, and chemical composition of the inflowing gas. The spectral diagnostics will enable measurements of the total mass and inflow rate of the accreting material. This study potentially offers a unique opportunity to quantitatively probe the mechanisms of black hole fueling, addressing a fundamental gap in our understanding of AGN physics and galaxy evolution.Summary of Program Goals:
This program aims to obtain UV spectra of J0233-0455, a z=0.78 quasar exhibiting redshifted, inflowing Mg II absorption at +800 km/s, to study the elusive process of gas accretion onto supermassive black holes (SMBHs). The UV spectroscopy will target key transitions including Ly-alpha, Ly-beta, the Lyman limit, C II, C IV, and O VI, allowing us to characterize the physical properties, ionization state, and chemical composition of the inflowing gas. The spectral diagnostics will enable measurements of the total mass and inflow rate of the accreting material.
STIS Configuration and visit schedules:
The program will use the E230M grating with a central wavelength of 2415 Ang and the 0.2"x0.2" aperture. The central wavelength provides coverage from 2000-2800 Ang, necessary to capture the Ly-alpha and C IV at 2170 and 2770 Ang for the target at redshift z=0.78. The total STIS exposure time for J0233-0455 is 5 orbits, divided into two visits of 3 and 2 orbits, in accordance with the scheduling efficiency guidelines in the STIS instrument handbook.
STIS Target Acquisition:
The coordinate of J0233-0455 is known to better than 0.1". An ACQ sequence is sufficient to center the quasar in the 0.2"x0.2" aperture at the start of each visit. The GALEX NUV magnitude of the quasar is (NUV)=17.4. Using the STIS Target Acquisition ETC, we find that a S/N >~ 40 can be achieved with an acquisition exposure time of 7 seconds.
COS Configuration:
We aim to cover Ly-beta (1832 Ang), O VI (1843 Ang), C II (1851 Ang) between 1826 and 1859 Ang using the G185M grating with central wavelength c1941, and the Lyman limit (1629 Ang) using G160M with central wavelength c1600. We will employ FP-POS offsets 2, 3, and 4 for G185M, and 1, 2, 3, 4 for G160M to ensure that each wavelength window is observed at least three times with different grating positions. The total COS exposure time for J0233-0455 is 4 orbits within one single visit.
COS Target Acquisition:
We will obtain an NUV image in ACQ/IMAGE mode, as the 2.5" COS entrance aperture is sufficient to center the quasar. No ACQ/SEARCH is required since the quasar coordinates are known to better than 0.1". The GALEX FUV magnitude of the quasar is (NUV) = 17.4. Using the COS Target Acquisition ETC, we find that MIRROR B must be used to avoid exceeding the bright limit, and that a S/N greater than 40 can be achieved with a 20-second exposure.PI W. Liu is a graduate student working on a thesis on the physical properties and incidence of diffuse nebulae around z=1 quasar hosts and has experience with HST absorption-line analysis and photoionization modelling and nebular line measurements in IFU data.
Co-PI Johnson, co-I's H.-W. Chen, Zahedy, Qu, Rudie, and Muzahid are leaders in high-resolution spectroscopy, absorption-line analysis, and ionization modeling, with a demonstrated track record and a combined total of over 100 refereed journal articles. All of them have a deep knowledge of absorption-line spectroscopy. In particular, Johnson, Chen, Muzahid, Qu, and Zahedy have extensive experiences working with and analyzing COS and STIS spectra, and have published numerous peer-reviewed papers based on these instruments since 2000.
Co-I's Boettcher and M. Chen are leading experts in studies of diffuse interstellar and circumgalactic gas. The primary research interests of Boettcher is in the disk-halo interface of nearby galaxies, while M. Chen focus on observations and interpretations of optical emission at intermediate redshift. Together they provide independent perspectives and important expertise in intermediate- and high- redshift gaseous halos that will help establish a general understanding of the cosmic evolution history of gas and galaxies based on the program data.
Co-I Li is an expert in AGN and galaxy evolution with significant experience in large surveys and high angular resolution imaging.
Co-I Schaye is a theorist in the study of cosmic gas evolution and its connection to galaxy formation and evolution. Schaye leads the EAGLE simulation group, providing valuable theoretical perspectives for the analyses and interpretations of the program data.
Co-I N. Mishra is a graduate student working on observations of the circumgalactic medium around low and intermediate redshift galaxies.
Co-I E.Kesler is a postbacc researcher at U. Michigan with significant experience measuring ionized line emission around AGN.
Co-I F. Wang is an expert in high-redshift quasars and serve as PIs for past HST programs. He has extensive experience with HST instruments and in analyzing the corresponding data.Supermassive Black Holes and Active GalaxiesGalaxies6falsefalsefalsefalsefalsefalsefalseSUPPORTEDGALAXYHALOLYMAN ALPHA CLOUDQSOQUASARNOJ2000J2000AB=17.4 in NUVSTIS/NUV-MAMASpectroscopicNoNoE230M2415COS/NUVSpectroscopicNoNoG185M1941COS/FUVSpectroscopicNoNoG160M1600/private/var/folders/vv/hbmb00y12cz071t7n2qt3kw80000gn/T/OPVisit16071391251479000879.xmlThe scheduling data was generated by CASM 34.0.CASM was run in Phase II mode.(Tic-Visit
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