Almost Optically Dark Galaxies in DECaLS (I): Detection, Optical Properties and Possible Origins
The Astrophysical Journal(2024)
摘要
We report the discovery of eight optical counterparts of ALFALFA
extragalactic objects from DECaLS, five of which are discovered for the first
time. These objects were flagged as HI emission sources with no optical
counterparts in SDSS before. Multi-band data reveal their unusual physical
properties. They are faint and blue (g-r=-0.35∼0.55), with quite low
surface brightness (μ_ g,peak=24.88∼26.41 mag/
arcsec^2), irregular morphologies, low stellar masses
(log_10(M_*/M_⊙)=5.27∼7.15), low star formation rates
(SFR=0.21∼9.24×10^-3 M_⊙ yr^-1), and remarkably
high HI-to-stellar mass ratios (log_10(M_ HI/M_*) = 1.72∼3.22,
except AGC 215415). They deviate from the scaling relations between HI and
optical properties defined by the ALFALFA sample and the baryonic Tully-Fisher
relation. They agree well with the main sequence of star-forming galaxies but
exhibit low star-forming efficiency. Based on their physical properties and
environments, we speculate that six of these objects may have originated from
tidal processes, while the remaining two appear to have isolated origins. They
may have had a relatively calm evolutionary history and only begun to form
stars recently.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要