分类： 天文学 >> 天文学 提交时间： 2023-02-19
Cheng Cheng
Jia-Sheng Huang
Christopher N. A. Willmer
Hong-Xin Zhang
Matthew L. N. Ashby
Hai Xu
Marcin Sawicki
Stephane Arnouts
Stephen Gwyn
Guillaume Desprez
Jean Coupon
Anneya Golob
Piaoran Liang
Tianwen Cao
Yaru Shi
Gaoxiang Jin
Chuan He
Shumei Wu
Zijian Li
Y. Sophia Dai
摘要： We present redshifts for 2753 low-redshift galaxies between $0.03 \lesssim z_{\rm spec}\lesssim0.5$ with 18 $\leq$ $r$ $\leq$ 22 obtained with Hectospec at the Multi-Mirror Telescope (MMT). The observations targeted the XMM-LSS, ELAIS-N1 and DEEP2-3 fields, each of which covers $\sim$ 1 deg$^2$. These fields are also part of the recently completed CFHT Large Area U-band Deep Survey (CLAUDS) and on-going Hyper Suprime-Cam deep fields surveys. The efficiency of our technique for selecting low-redshift galaxies is confirmed by the redshift distribution of our sources. In addition to redshifts, these high S/N spectra are used to measure ages, metallicities, and nuclear activity levels. In combination with the photometric catalogue in $u$, $g$, $r$, $i$, $z$, $y$ down to 27 AB mag, we are able to study the galaxy population down to stellar masses of $\sim$ 10$^8 M_\odot$ . This paper presents the observational strategy, the reduction procedure and properties of the galaxy sample.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Cheng Cheng
Jia-Sheng Huang
Hai Xu
Gaoxiang Jin
Chuan He
Tianwen Cao
Zijian Li
Shumei Wu
Piaoran Liang
Yaru Shi
Xu Shao
Y. Sophia Dai
Cong Kevin Xu
Marat Musin
摘要： The Spitzer Extended Deep Survey (SEDS) as a deep and wide mid-infrared (MIR) survey project provides a sample of 500000+ sources spreading 1.46 square degree and a depth of 26 AB mag (3$\sigma$). Combining with the previous available data, we build a PSF-matched multi-wavelength photometry catalog from u band to 8$\mu$m. We fit the SEDS galaxies spectral energy distributions by the local galaxy templates. The results show that the SEDS galaxy can be fitted well, indicating the high redshift galaxy ($z \sim 1$) shares the same templates with the local galaxies. This study would facilitate the further study of the galaxy luminosity and high redshift mass function.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Gaoxiang Jin
Y. Sophia Dai
Hsi-An Pan
Lihwai Lin
Cheng Li
Bau-Ching Hsieh
Shiyin Shen
Fang-Ting Yuan
Shuai Feng
Cheng Cheng
Hai Xu
Jia-Sheng Huang
Kai Zhang
摘要： The role of active galactic nuclei (AGNs) during galaxy interactions and how they influence the star formation in the system are still under debate. We use a sample of 1156 galaxies in galaxy pairs or mergers (hereafter `pairs') from the MaNGA survey. This pair sample is selected by the velocity offset, projected separation, and morphology, and is further classified into four cases along the merger sequence based on morphological signatures. We then identify a total of 61 (5.5%) AGNs in pairs based on the emission-line diagnostics. No evolution of the AGN fraction is found, either along the merger sequence or compared to isolated galaxies (5.0%). We observe a higher fraction of passive galaxies in galaxy pairs, especially in the pre-merging cases, and associate the higher fraction to their environmental dependence. The isolated AGN and AGN in pairs show similar distributions in their global stellar mass, star formation rate (SFR), and central [OIII] surface brightness. AGNs in pairs show radial profiles of increasing specific SFR and declining Dn4000 from center to outskirts, and no significant difference from the isolated AGNs. This is clearly different from star-forming galaxies (SFGs) in our pair sample, which show enhanced central star formation, as reported before. AGNs in pairs have lower Balmer decrements at outer regions, possibly indicating less dust attenuation. Our findings suggest that AGNs likely follow an inside-out quenching and the merger impact on the star formation in AGNs is less prominent than in SFGs.
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