Guanwen Fang

PASSIVE AND STAR-FORMING GALAXIES AT 1.4 ⩽ z ⩽ 2.5 IN THE AEGIS FIELD

Using a simple two-color selection based on g-, z-, and K-band photometry, we choose from 1609 star-forming galaxies (sgzKs) and 422 passively evolving galaxies (pgzKs) at z similar to 2 from a K-band-selected sample (K-AB 10(41) erg s(-1).

Structure and Morphology of X-Ray-selected Active Galactic Nucleus Hosts at 1 < z < 3 in the CANDELS-COSMOS Field

We analyze morphologies of the host galaxies of 35 X-ray-selected active galactic nuclei (AGNs) at z similar to 2 in the Cosmic Evolution Survey field using Hubble Space Telescope/WFC3 imaging taken from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. We build a control sample of 350 galaxies in total by selecting 10 non-active galaxies drawn from the same field with a similar stellar mass and redshift for each AGN host. By performing two-dimensional fitting with GALFIT on the surface brightness profile, we find that the distribution of the Sersic index (n) of AGN hosts does not show a statistical difference from that of the control sample. We measure the nonparametric morphological parameters (the asymmetry index A, the Gini coefficient G, the concentration index C, and the M-20 index) based on point-source-subtracted images. All the distributions of these morphological parameters of AGN hosts are consistent with those of the control sample. We finally investigate the fraction of distorted morphologies in both samples by visual classification. Only similar to 15% of the AGN hosts have highly distorted morphologies, possibly due to a major merger or interaction. We find there is no significant difference in the distortion fractions between the AGN host sample and control sample. We conclude that the morphologies of X-ray-selected AGN hosts are similar to those of non-active galaxies and most AGN activity is not triggered by a major merger.

THE MOST LUMINOUS HEAVILY OBSCURED QUASARS HAVE A HIGH MERGER FRACTION: MORPHOLOGICAL STUDY OF WISE-SELECTED HOT DUST-OBSCURED GALAXIES

Previous studies have shown that WISE-selected hyperluminous, hot dust-obscured galaxies (Hot DOGs) are powered by highly dust-obscured, possibly Compton-thick AGNs. High obscuration provides us a good chance to study the host morphology of the most luminous AGNs directly. We analyze the host morphology of 18 Hot DOGs at

Classification of extremely red objects in the Hubble Ultra Deep Field

z\sim3

ULTRALUMINOUS INFRARED GALAXIES IN THE WISE AND SDSS SURVEYS

using Hubble Space Telescope/WFC3 imaging. We find that Hot DOGs have a high merger fraction (

The metallicity evolution of blue compact dwarf galaxies from the intermediate redshift to the local Universe

62\pm 14 \%

Selection and Mid-infrared Spectroscopy of Ultraluminous Star-forming Galaxies at z ~ 2

). By fitting the surface brightness profiles, we find that the distribution of Sersic indices in our Hot DOG sample peaks around 2, which suggests that most of Hot DOGs have transforming morphologies. We also derive the AGN bolometric luminosity (

Spectroscopic Observation and Analysis of H ii Regions in M33 with MMT: Temperatures and Oxygen Abundances

\sim10^{14}L_\odot

Morphology and structure of BzK-selected galaxies at z ∼ 2 in the CANDELS-COSMOS field*

) of our Hot DOG sample by using IR SEDs decomposition. The derived merger fraction and AGN bolometric luminosity relation is well consistent with the variability-based model prediction (Hickox et al. 2014). Both the high merger fraction in IR-luminous AGN sample and relatively low merger fraction in UV/optical-selected, unobscured AGN sample can be expected in the merger-driven evolutionary model. Finally, we conclude that Hot DOGs are merger-driven and may represent a transit phase during the evolution of massive galaxies, transforming from the dusty starburst dominated phase to the unobscured QSO phase.

Compact star forming galaxies as the progenitors of compact quiescent galaxies: Clustering result

We present a quantitative study of the classification of Extremely Red Objects (EROs). The analysis is based on the multi-band spatial- and ground-based observations (HST/ACS- BV iz , HST/NICMOS- JH , VLT- JHK ) in the Hubble Ultra Deep Field (UDF). Over a total sky area of 5.50 arcmin 2 in the UDF, we select 24 EROs with the color criterion ( i - K ) Vega > 3.9 , corresponding to ( I - K ) Vega >4.0 , down to K Vega = 22 . We develop four methods to classify EROs into Old passively evolving Galaxies (OGs) and Dusty star-forming Galaxies (DGs), including ( i - K ) vs. ( J - K ) color diagram, spectral energy distribution fitting method, Spitzer MIPS 24 μm image matching, and nonparametric measure of galaxy morphology, and found that the classification results from these methods agree well. Using these four classification methods, we classify our EROs sample into 6 OGs and 8 DGs to K Vega K Vega K Vega K Vega i, z and HST/NICMOS- J,H bands.We find that the morphological parameters of galaxies in our sample depend on the wavelength of observation, which suggests that caution is necessary when comparing single wavelength band images of galaxies at a variety of redshifts.