arXiv subjects

Jianhang Chen

Publications and source records attributed to Jianhang Chen.

40 records · Page 3Linked to original sources

arXiv2020

Host Galaxy Properties of Changing-look AGN Revealed in the MaNGA Survey

Changing-look Active Galactic Nuclei (CL-AGNs) are a subset of AGNs in which the broad Balmer emission lines appear or disappear within a few years. We use the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey to identify five CL-AGNs. The 2-D photometric and kinematic maps reveal common features as well as some unusual properties of CL-AGN hosts as compared to the AGN hosts in general. All MaNGA CL-AGNs reside in the star-forming main sequence, similar to MaNGA non-changing-look AGNs (NCL-AGNs). The $80\% \pm 16\%$ of our CL-AGNs do possess pseudo-bulge features, and follow the overall NCL-AGNs $M_{BH}-σ_{*}$ relationship. The kinematic measurements indicate that they have similar distributions in the plane of angular momentum versus galaxy ellipticity. MaNGA CL-AGNs however show a higher, but not statistically significant ($20\% \pm 16\%$) fraction of counter-rotating features compared to that ($1.84\% \pm 0.61\%$) in general star-formation population. In addition, MaNGA CL-AGNs favor more face-on (axis ratio $>$ 0.7) than that of Type I NCL-AGNs. These results suggest that host galaxies could play a role in the CL-AGN phenomenon.

astro-ph.GA↗

arXiv2019

Multi-View Matching Network for 6D Pose Estimation

Applications that interact with the real world such as augmented reality or robot manipulation require a good understanding of the location and pose of the surrounding objects. In this paper, we present a new approach to estimate the 6 Degree of Freedom (DoF) or 6D pose of objects from a single RGB image. Our approach can be paired with an object detection and segmentation method to estimate, refine and track the pose of the objects by matching the input image with rendered images.

cs.CV↗

arXiv2019

The spatial extension of extended narrow line regions in MaNGA AGN

In this work, we revisit the size-luminosity relation of the extended narrow line regions (ENLRs) using a large sample of nearby active galactic nuclei (AGN) from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. The ENLRs ionized by the AGN are identified through the spatially resolved BPT diagram, which results in a sample of 152 AGN. By combining our AGN with the literature high-luminosity quasars, we found a tight log-linear relation between the size of the ENLR and the AGN [O III]λ5007Å luminosity over four orders of magnitude of the [O III] luminosity. The slope of this relation is 0.42 $\pm$ 0.02 which can be explained in terms of a distribution of clouds photoionized by the AGN. This relation also indicates the AGN have the potential to ionize and heat the gas clouds at a large distance from the nuclei without the aids of outflows and jets for the low-luminosity Seyferts.

astro-ph.GA↗

arXiv2019

What drives the velocity dispersion of ionized gas in star-forming galaxies?

We analyze the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with star formation rates (SFRs), SFR surface densities ($\rm{Σ_{SFR}}$), stellar masses and stellar mass surface densities ($\rm{Σ_{*}}$). By combining with high z galaxies, we found that there is a good correlation between the velocity dispersion and the SFR as well as $\rm{Σ_{SFR}}$. But the correlation between the velocity dispersion and the stellar mass as well as $\rm{Σ_{*}}$ is moderate. By comparing our results with predictions of theoretical models, we found that the energy feedback from star formation processes alone and the gravitational instability alone can not fully explain simultaneously the observed velocity-dispersion/SFR and velocity-dispersion/$\rm{Σ_{SFR}}$ relationships.

astro-ph.GA↗