In this issue
Palomar Science Highlight: Discovery of Inflow Fueling of Supermassive Black Hole Close to the Accretion Disk
By Xiheng Shi (Polar Research Institute of China)
A research group from Polar Research Institute of China (PRIC) recently identified a fast gaseous inflow fueling the accretion disk around a supermassive black hole in the quasar J1035+1422. The discovery is based on the spectra obtained using the Palomar 200-inch telescope. The inflow is traced by a redshifted broad-absorption-line system. Located at the outer radius of the accretion disk, this inflow is the first case reported actually reaching the disk. The result is published in a Letter to Nature on September 4, 2019.
The absorption-line system was originally detected through a systematic search in ~105 SDSS quasars with z < 1.3. In the follow-up campaign with the DBSP and TripleSpec spectrographs, the system was confirmed using H I Balmer absorption from H-α to H-η and metastable He I multiplets He I* ll3,188,3,889,10,830A in the optical and near-infrared spectra. The absorption trough spreads 0 - 5,000 km/s redshifted to the quasar's rest frame. This is the fastest and broadest among the sample of absorption line systems. This large velocity width implies a fast inward motion. Our photoionization simulation presented in the paper suggests that the inflow reaches 1,100 gravitational radii from the central engine, overlapping with the outer accretion disk. The inflow could originate near the inner surface of the dusty torus, and the mass flux rate is therefore about 15 – 36 solar masses per year, sufficient to power the quasar radiation and the outflow.
Such inflow directly feeding the accretion disk is considered the last piece of the puzzle of quasar black hole accretion. Because of potential dust obscuration, such inflow around supermassive black hole could be much more common in quasars than as suggested by ultraviolet and optical spectra. Absorption/emission lines in the infrared, (sub)millimetre and radio wavelengths, where dust obscuration is small or negligible, could be more powerful means to study these disk-feeding inflows.
By Seth Meeker (JPL)
PALM-3000 (P3K), the Palomar 200-inch facility adaptive optics system, has undergone a significant upgrade during the 2019B observing semester, concluding with a successful re-commissioning phase in September/October 2019 and a return to science operations as scheduled on 08 November 2019. The main features of this upgrade are: 1) the original frame-transfer CCD wavefront sensor (WFS) is upgraded to an OCAM2K EMCCD capable of 3.5 kHz framerates; 2) new real-time control (RTC) hardware and software based on advanced Digital Signal Processor (DSP) boards has replaced the aging GPU based RTC system.
Similar to the pre-upgrade system, P3K’s Shack-Hartmann WFS supports multiple pupil sampling modes using a motorized lenslet stage, and these pupil sampling modes are being released to general observing in phases. The default sampling mode with 64×64 sub-apertures was the first to be tested on-sky during the September/October re-commissioning, and is now available for normal science observations. In 64× mode the upgraded P3K is already achieving K-band Strehl ratios‐the ratio of PSF core intensity vs. a theoretically perfect PSF—up to 85% on-sky and can lock on natural guide stars (NGS) as faint as mV=16, rivaling or exceeding the natural guide star capabilities of facility NGS systems on much larger telescopes. The clearest improvement is in the quality of correction for a given guide star magnitude. Compared to the old system, the new system offers the same level of performance for guide stars that are 2 or 3 magnitudes fainter. For example, the upgraded system achieved Strehl ratios of 35% on a mV=14 guide star on a good night (in terms of atmospheric conditions) during re-commissioning. The previous system could achieve that on an mV=11 guide star on an excellent night. This is directly thanks to the new EMCCD wavefront sensor with its sub-electron read-noise, compared to the several-electron read-noise of the old camera. Early results from this upgrade can be found on the P3K observer webpage to aid in observation planning with these new capabilities.
The next phase will be the 16×16 subaperture mode, which is scheduled for on-sky commissioning in January 2020 and science use starting in the 2020A semester. This mode is expected to extend the system’s faint limit by two more magnitudes, while offering superior correction to the 64× mode for targets fainter than ~11th magnitude.
Every successful night at the Palomar 200-inch telescope relies on excellent support from many staff members at Palomar mountain. With this series, we introduce these dedicated people to our P200 user community. Our first profile is on Support Astronomer Carolyn Heffner.
Carolyn Heffner, from Cleona, Pennsylvania, is a support astronomer at Palomar Observatory. She became interested in astronomy while studying physics at Lafayette College and continued her education by completing a master’s degree in astronomy at San Diego State University. As a student at SDSU, Carolyn worked at Mount Laguna Observatory with former director Paul Etzel. Her experiences there gave her a great foundation for a career working at observatories, and she became a Palomar staff member in 2011.
As a support astronomer, Carolyn helps visiting astronomers with their observations on the 200-inch Hale Telescope by training them how to use instrument software and by ensuring their telescope time goes smoothly. The instrumentation she works with includes optical and infrared spectrographs and direct imaging cameras, as well as the 200-inch adaptive optics system. She also supports work being performed at the 48-inch and 60-inch telescopes. Her additional duties include mirror aluminizing, mirror quality assessment, on-site computer and networking support, and various other projects as they arise.
Note to all P200 Observers: As announced in a previous newsletter, our P200 Remote Observing policies were recently updated. All potential remote observers are encouraged to review the updates at the COO remote observing page—in particular the Remote Observing Guidelines document.
Questions? We've answered many common visiting, media, and academic questions in our public FAQ page.