Recently, a team led by Dr. Zheng Zhenya, a researcher at the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, and the China Space Station Telescope (CSST) Multichannel Imaging Instrument Team along with the Early Universe and High Redshift Galaxy Task Force, collaborated with multiple domestic and international research institutions to conduct in-depth research on narrowband observations made by the Hubble Space Telescope (HST). They carried out a comprehensive statistical analysis, releasing the deepest narrowband deep space images based on HST data and successfully identified a series of emission-line galaxies. The relevant findings were published in the "Journal of Astrophysics and Astronomy Supplement Series."
The research team systematically analyzed a large amount of narrowband observation data from the HST, using a spherical, same-latitude equal-area pixelization algorithm to comprehensively analyze narrowband observation data from four major imaging instruments of the HST since 1999. Researchers found that in the GOODS-South Deep Field, the HST accumulated nearly 200,000 seconds of narrowband observations using advanced survey cameras' hydrogen-alpha filter. These observation data were collected in 2009 and included 72 orbits of deep observations by the HST, demonstrating extremely high scientific value.
The coverage area of the HDHα images (narrow-band images) is sourced from the "Journal of Astrophysics Supplement Series".
Upon a thorough examination of this dataset, the team identified significant cosmic ray contamination in the narrow-band data images. Leveraging the latest and deepest HLF deep field within this dataset, the team performed precise alignment based on the positioning of intermediate-brightness sources, grouping individual exposures by positional offsets. These grouped data were then combined into an intermediate image with increased depth to enhance the accuracy and effectiveness of the alignment process, followed by merging to obtain the final image. The processed narrow-band deep field observations accumulated a total exposure time of 196,000 seconds over an effective observation area of 76 square arcminutes, with cumulative exposure time exceeding 60,000 seconds in the deepest regions. Subsequently, the research team conducted detailed inspections of the point spread function quality, data depth, and alignment accuracy, indicating high-quality data.
Furthermore, the research team utilized the obtained narrow-band images along with existing wide-band images from the HST Advanced Camera for Surveys to generate a multi-band catalog based on narrow-band images. Using this catalog, they conducted a thorough search for emission-line galaxies in the region, successfully identifying a sample including high-redshift Lyman-alpha galaxies. Currently, follow-up studies on these high-redshift Lyman-alpha galaxies are actively underway.
It is noted that the multi-channel imager carried by the CSST is also capable of conducting narrow-band sky surveys. Zheng Zhenya pointed out that this multi-channel imager on the CSST can simultaneously image in three different channels, utilizing wide-band data to assist in aligning narrow-band images, thus greatly simplifying the data processing workflow. More importantly, China's space station telescope boasts a larger field of view than the HST, enabling astronomers to conduct narrow-band surveys more efficiently and providing richer data resources for relevant scientific research.
Related paper information: http://doi.org/10.3847/1538-4365/ad148b
