Low-mass young stellar population and star formation history of the
  cluster IC 1805 in the W4 H{\sc ii} region
  W4 is a giant H{\sc ii} region ionized by the OB stars of the cluster
IC~1805. The H{\sc ii} region/cluster complex has been a subject of numerous
investigations as it is an excellent laboratory for studying the feedback
effect of massive stars on the surrounding region. However, the low-mass
stellar content of the cluster IC~1805 remains poorly studied till now. With
the aim to unravel the low-mass stellar population of the cluster, we present
the results of a multiwavelength study based on deep optical data obtained with
the Canada-France-Hawaii Telescope, infrared data from 2MASS, $Spitzer$ Space
Telescope and X-ray data from $Chandra$ Space Telescope. The present optical
dataset is complete enough to detect stars down to 0.2~M$_\odot$, which is the
deepest optical observations so far for the cluster. We identified 384
candidate young stellar objects (YSOs; 101 Class I/II and 283 Class III) within
the cluster using various colour-colour and colour-magnitude diagrams. We
inferred the mean age of the identified YSOs to be $\sim$ 2.5 Myr and mass in
the range 0.3 - 2.5 M$_\odot$. The mass function of our YSO sample has a power
law index of -1.23 $\pm$ 0.23, close to the Salpeter value (-1.35), and
consistent with those of other star-forming complexes. We explored the disk
evolution of the cluster members and found that the diskless sources are
relatively older compared to the disk bearing YSO candidates. We examined the
effect of high-mass stars on the circumstellar disks and found that within
uncertainties, the influence of massive stars on the disk fraction seems to be
insignificant. We also studied the spatial correlation of the YSOs with the
distribution of gas and dust of the complex to conclude that IC 1805 would have
formed in a large filamentary cloud.
