Search

The velocity “kink” kinematic signature has gained standing as a promising method for discovering embedded planets. The gravitational influence of a planetary perturber is predicted to drive spiral wakes that disturb the surrounding gas velocity, generating distinct “kinks” along the spiral arms observable in velocity channel maps of gas emission. To date, a dozen velocity kink detections have been reported in ALMA observations of disks, and most have pinpointed the candidate planets within gaps in the ALMA dust continuum. The understanding that velocity kinks are due to spiral arms enables us to make a robust, testable prediction: Every instance of velocity kinks should be concurrent with spiral density waves. In this talk, I describe the results from our search for the spirals driven by the kink planets in the ALMA dust continuum. Our work provides an independent method to verify the existence of these planet candidates, and more importantly, tests the validity of velocity kinks as a reliable signpost of planets in disks.

We present a high-contrast imaging search for Pa$��$ line emission from protoplanets in the PDS~70 system with Keck/OSIRIS integral field spectroscopy. We applied the high-resolution spectral differential imaging technique to the OSIRIS $J$-band data but did not detect the Pa$��$ line at the level predicted using the parameters of \cite{Hashimoto2020}. This lack of Pa$��$ emission suggests the MUSE-based study may have overestimated the line width of H$��$. We compared our Pa$��$ detection limits with the previous H$��$ flux and H$��$ limits and estimated $A_{\rm V}$ to be $\sim0.9$ and 2.0 for PDS~70~b and c respectively. In particular, PDS~70~b's $A_{\rm V}$ is much smaller than implied by high-contrast near-infrared studies, which suggests the infrared-continuum photosphere and the hydrogen-emitting regions exist at different heights above the forming planet., 8pages, 5 figs, accepted for publication in AJ

(abridged) The Atacama Large Millimeter/submillimeter Array (ALMA) was the top-ranked priority for a new ground-based facility in the 2000 Canadian Long Range Plan. Ten years later, at the time of LRP2010, ALMA construction was well underway, with first science observations anticipated for 2011. In the past 8 years, ALMA has proved itself to be a high-impact, high-demand observatory, with record numbers of proposals submitted to the annual calls and large numbers of highly cited scientific papers across fields from protoplanetary disks to high-redshift galaxies and quasars. The LRP2010 ALMA white paper laid out 8 specific metrics that could be used to judge the success of Canada's participation in ALMA. Among these metrics were publications (number; impact), collaborations (international; multi-wavelength), and student training. To call out one particular metric, Canadians are making excellent use of ALMA in training graduate students and postdocs: as of June 2018, 12 of 23 Canadian first-author papers were led by a graduate student, and a further 4 papers were led by postdocs. All 8 metrics argue for Canada's involvement in ALMA over the past decade to be judged a success. The successful achievement of these wide-ranging goals argues strongly for Canada's continuing participation in ALMA over the next decade and beyond. Looking forward, our community needs to: (1) maintain Canadian access to ALMA and our competitiveness in using ALMA; (2) preserve full Canadian funding for our share of ALMA operations; (3) identify components of ALMA development in which Canada can play a significant role, including stimulating expertise in submillimetre instrumentation to capitalize on future opportunities; and (4) keep Canadians fully trained and engaged in ALMA, as new capabilities become available, reaching the widest possible community of potential users., Comment: White paper E004 submitted to the Canadian Long Range Plan 2020

We present $H$- and $K_{\rm s}$-bands observations of the LkH$��$ 330 disk with a multi-band detection of the large gap and spiral-like structures. The morphology of the outer disk ($r\sim$$0\farcs3$) at PA=0--45$^\circ$ and PA=180--290$^\circ$ are likely density wave-induced spirals and comparison between our observational results and simulations suggests a planet formation. We have also investigated the azimuthal profiles at the ring and the outer-disk regions as well as radial profiles in the directions of the spiral-like structures and semi-major axis. Azimuthal analysis shows a large variety in wavelength and implies that the disk has non-axisymmetric dust distributions. The radial profiles in the major-axis direction (PA=$271^\circ$) suggest that the outer region ($r\geq0\farcs25$) may be influenced by shadows of the inner region of the disk. The spiral-like directions (PA=10$^\circ$ and 230$^\circ$) show different radial profiles, which suggests that the surfaces of the spiral-like structures are highly flared and/or have different dust properties. Finally, a color-map of the disk shows a lack of an outer eastern region in the $H$-band disk, which may hint the presence of an inner object that casts a directional shadow onto the disk., 12pages, 16 figures, 2 tables, accepted for publication in AJ

ALMA has revolutionized our view of protoplanetary disks, revealing structures such as gaps, rings and asymmetries that indicate dust trapping as an important mechanism in the planet formation process. However, the high resolution images have also shown that the optically thin assumption for millimeter continuum emission may not be valid and the low values of the spectral index may be related to optical depth rather than dust growth. Longer wavelength observations are essential to properly disentangle these effects. The high sensitivity and spatial resolution of the next-generation Very Large Array (ngVLA) will open up the possibilities to spatially resolve disk continuum emission at centimeter wavelengths and beyond, which allows the study of dust growth in disks in the optically thin regime and further constrain models of planet formation., Comment: To be published in the ASP Monograph Series, "Science with a Next-Generation VLA", ed. E. J. Murphy (ASP, San Francisco, CA)

The Gemini Planet Imager Exoplanet Survey (GPIES) is a 600-star survey for young Jovian-mass exoplanets at Solar System scales. To date, GPIES has imaged six exoplanets and four brown dwarfs and has developed the data reduction tools necessary to characterize these companions. GPI is therefore building up a uniform library of 1 to 2.4 micron near-infrared low-resolution spectra of young substellar objects. A more thorough comparison with libraries of field and young brown dwarf near-infrared spectra is now possible to detail similarities and difference between the two families. I will present the current status of the library, discuss how these objects sample different regimes of atmospheric properties, and how similar they are to young free-floating planetary mass objects. I will also show the orbits of these companions and discuss what inferences we can make from their dynamics.

We present a systematic X-ray study, the third in a series, of 49 active galactic nuclei with intermediate-mass black holes (IMBH; ~10^5-10^6 M_sun) using Chandra observations. We detect 42 out of 49 targets with a 0.5-2 keV X-ray luminosity 10^41-10^43 erg/s. We perform spectral fitting for the 10 objects with enough counts (>200), and they are all well fit by a simple power-law model modified by Galactic absorption, with no sign of significant intrinsic absorption. While we cannot fit the X-ray spectral slope directly for the rest of the sample, we estimate it from the hardness ratio and find a range of photon indices consistent with those seen in more luminous and massive objects. The X-ray-to-optical spectral slope (alphaox) of our IMBH sample is systematically flatter than in active galaxies with more massive black holes, consistent with the well-known correlation between alphaox and UV luminosity. Thanks to the wide dynamic range of our sample, we find evidence that alphaox increases with decreasing M_BH as expected from accretion disk models, where the UV emission systematically decreases as M_BH decreases and the disk temperature increases. We also find a long tail toward low alphaox values. While some of these sources may be obscured, given the high L_bol/L_Eddington values in the sample, we argue that some may be intrinsically X-ray-weak, perhaps owing to a rare state that radiates very little coronal emission., 13 pages (double columns), 2 tables, 9 figures, ApJ accepted

The discovery of thousands of exoplanets over the last couple of decades has shown that the birth of planets is a very efficient process in nature. Theories invoke a multitude of mechanisms to describe the assembly of planets in the disks around pre-main-sequence stars, but observational constraints have been sparse on account of insufficient sensitivity and resolution. Understanding how planets form and interact with their parental disk is crucial also to illuminate the main characteristics of a large portion of the full population of planets that is inaccessible to current and near-future observations. This White Paper describes some of the main issues for our current understanding of the formation and evolution of planets, and the critical contribution expected in this field by the Next Generation Very Large Array., 6 pages, 3 figures, White Paper submitted to the National Academies of Science, Engineering, and Medicine's Exoplanet Science Strategy Call for Papers