Title:Searching for variable objects on near-infrared images taken by MODS 
Author(s):Misa Sakata,Takashi Ichikawa,Masaru Kajisawa,Tomoki Morokuma,MODS Group
Abstract:
We present the first result of searching for variable objects on
near-infrared deep images in GOODS-N region.
We used $K_s$ band images of MOIRCS Deep Survey (MODS) (3 $\times$ 7
arcmin) in 3 epochs with one year interval. We made a reference
image, which is the average of the 3 epoch images. Then the
reference image was subtracted from the image of each epoch.
We detected point-like sources on the subtracted images with the
confidence level of 5$\sigma$. The sources are the candidates of
variable objects.
Some are coincident with X-ray sources detected by
Chandra with a small offset from the center of their host galaxies.
They are reasonably considered to be AGNs.
Some with a large offset would be candidates of supernovae.
The redshift of most of the host galaxies are spectroscopically
obtained. The redshift distribution of the variable objects widely spreads.
We evaluated the detection limit by embedding artificial sources in
original images and detecting them with the same manner of our candidates.
Although the detection limit is shallower than those of other
recent variable object surveys made in optical wavelength,
we found more variable objects than optical results.
The fact suggests that many variable objects are obscured
by dust in host galaxies.