Detection of stellar light from quasar host galaxies at redshifts above 6.

The detection of starlight from the host galaxies of quasars during the reionization epoch (z > 6) has been elusive, even with deep Hubble Space Telescope observations1,2. The current highest redshift quasar host detected3, at z = 4.5, required the magnifying effect of a foreground lensing galaxy. Low-luminosity quasars4-6 from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP)7 mitigate the challenge of detecting their underlying, previously undetected host galaxies. Here we report rest-frame optical images and spectroscopy of two HSC-SSP quasars at z > 6 with the JWST. Using near-infrared camera imaging at 3.6 and 1.5 µm and subtracting the light from the unresolved quasars, we find that the host galaxies are massive (stellar masses of 13 × and 3.4 × 1010 M☉, respectively), compact and disc-like. Near-infrared spectroscopy at medium resolution shows stellar absorption lines in the more massive quasar, confirming the detection of the host. Velocity-broadened gas in the vicinity of these quasars enables measurements of their black hole masses (1.4 × 109 and 2.0 × 108 M☉, respectively). Their location in the black hole mass-stellar mass plane is consistent with the distribution at low redshift, suggesting that the relation between black holes and their host galaxies was already in place less than a billion years after the Big Bang.

Demonstration of wideband metal mesh filters for submillimeter astrophysics using flexible printed circuits.

We developed a wideband quasi-optical band-pass filter covering 170-520 GHz by exploiting the recent advancements in commercially available flexible printed circuit (FPC) fabrication technologies. We designed and fabricated a three-layered stack of loaded hexagonal grid metal meshes using a copper pattern with a narrowest linewidth of 50µm on a polyimide substrate. The measured frequency passband shape was successfully reproduced through a numerical simulation using a set of parameters consistent with the dimensions of the fabricated metal meshes. FPC-based metal mesh filters will provide a new pathway toward the on-demand development of millimeter/submillimeter-wave quasi-optical filters at low cost and with a short turnaround time.

Spatial correlation between submillimetre and Lyman-alpha galaxies in the SSA 22 protocluster.

Lyman-alpha emitters are thought to be young, low-mass galaxies with ages of approximately 10(8) yr (refs 1, 2). An overdensity of them in one region of the sky (the SSA 22 field) traces out a filamentary structure in the early Universe at a redshift of z approximately 3.1 (equivalent to 15 per cent of the age of the Universe) and is believed to mark a forming protocluster. Galaxies that are bright at (sub)millimetre wavelengths are undergoing violent episodes of star formation, and there is evidence that they are preferentially associated with high-redshift radio galaxies, so the question of whether they are also associated with the most significant large-scale structure growing at high redshift (as outlined by Lyman-alpha emitters) naturally arises. Here we report an imaging survey of 1,100-microm emission in the SSA 22 region. We find an enhancement of submillimetre galaxies near the core of the protocluster, and a large-scale correlation between the submillimetre galaxies and the low-mass Lyman-alpha emitters, suggesting synchronous formation of the two very different types of star-forming galaxy within the same structure at high redshift. These results are in general agreement with our understanding of the formation of cosmic structure.

Supermassive black hole feeding and feedback observed on subparsec scales.

Active galaxies contain a supermassive black hole at their center that grows by accreting matter from the surrounding galaxy. The accretion process in about the central 10 parsecs has not been directly resolved in previous observations because of the small apparent angular sizes involved. We observed the active nucleus of the Circinus Galaxy using submillimeter interferometry. A dense inflow of molecular gas was evident on subparsec scales. We calculated that less than 3% of this inflow is accreted by the black hole, with the rest being ejected by multiphase outflows, providing feedback to the host galaxy. Our observations also reveal a dense gas disk surrounding the inflow that is gravitationally unstable, which drives the accretion into about the central 1 parsec.

Detection of an oxygen emission line from a high-redshift galaxy in the reionization epoch.

The physical properties and elemental abundances of the interstellar medium in galaxies during cosmic reionization are important for understanding the role of galaxies in this process. We report the Atacama Large Millimeter/submillimeter Array detection of an oxygen emission line at a wavelength of 88 micrometers from a galaxy at an epoch about 700 million years after the Big Bang. The oxygen abundance of this galaxy is estimated at about one-tenth that of the Sun. The nondetection of far-infrared continuum emission indicates a deficiency of interstellar dust in the galaxy. A carbon emission line at a wavelength of 158 micrometers is also not detected, implying an unusually small amount of neutral gas. These properties might allow ionizing photons to escape into the intergalactic medium.