An Hα Imaging Survey of the Low Surface Brightness Galaxies Selected from the Spring Sky Region of the 40% ALFALFA H i Survey

Abstract

We present a narrow Hα-band imaging survey of 357 low surface brightness galaxies (LSBGs) that are selected from the spring sky region of the 40% Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) HI Survey. All the Hα images are obtained from the 2.16 m telescope, operated by Xinglong Observatory of the National Astronomical Observatories, Chinese Academy of Sciences. We provide the Hα fluxes and derive the global star formation rates (SFRs) of LSBGs after the Galactic extinction, internal extinction, and [NII] contamination correction. Comparing to normal star-forming galaxies, LSBGs have a similar distribution in the HI surface density (Σ HI ), but their SFRs and star formation surface density (Σ SFR ) are much lower. Our results show that the gas-rich LSBGs selected from the ALFALFA survey obviously deviate from the Kennicutt-Schmidt law, in the relation between the star formation surface density (Σ SFR ) and the gas surface density (Σ gas ). However, they follow the extended Schmidt law well when taking the stellar mass of the galaxy into consideration.

UV and NIR size of the HI selected low surface brightness galaxies

“…Our previous series study based on the LSBGs selected from ALFALFA sample with optical surface brightness measured from SDSS images (Du et al 2015;He et al 2019;Du et al 2019) have shown that the LSBGs have much lower metallicity (Du et al 2017), follow the Tully-Fisher relation (Du et al 2019), and have similar mass-light ratios to the high surface brightness galaxies (Du et al 2020). The Hα images of our HI selected LSBG sample also shows that the star formation surface density has a very weak correlation with the gas surface density, the star formation surface density is much lower than the prediction of Kennicutt-Schmidt law (Kennicutt 1998;Kennicutt & Evans 2012), leading to a significantly longer gas depletion time scales, and low star formation efficiency (Lei et al 2018(Lei et al , 2019.…”

Fundamental Properties of the Dark and the Luminous Matter from the Low Surface Brightness Discs

“…One reason for such high values is the low density of their gaseous disks that prevents an efficient star formation ( [33,183]) capable to turn the primordial HI disc in a stellar one as it occurs in HSB spirals. In fact, in LSB galaxies we find: Σ H I ∼ 5 M pc −2 (see Figures 6and 14, [200,203]) a value that is about half or less that in HSB galaxies of similar stellar mass ( [34]) and, therefore, according to the Kennicutt criteria [218,219], a value which is below the star formation threshold ( [34,199,219,220]) implying that the gas is not ready to collapse and form stars [34,150,[221][222][223]. In fact, the star formation rate (SFR) in LSBs is very low, usually 0.1 M yr −1 , i.e., at least one order of magnitude lower than in HSB spirals ( [200,224], see also Table 3 in [225] and Table 2 in [203]).…”

“…LSBs galaxies are (obviously) characterised by low surface density exponential stellar discs [200][201][202]. Inside their 25 B magnitude isophotal radii, the stellar disk surface densities < Σ > are in the range (10 to 20) M /pc 2 (see Table 2 in [203]), values about 5-10 times smaller than those in HSB spirals of similar stellar disk masses. Noticeably, LSBs cover, in the range of their stellar disk masses M D , the whole range found in spirals, from ∼10 7 M to ∼10 11 M (see Figures 8,11 and 12).…”

“…HI radio observations indicate that LSB galaxies have very extended gaseous discs (out to several R opt ) with masses M H I ranging between 10 8 and 10 10 M ( [196,203,206]), i.e., of the order of their stellar disc masses M D (see Figure 8 and Table 2 in [203]). In spirals the ratio M H I /M D , instead, varies from 10 to 0.1 along their magnitudes range.…”

Constraining Dark matter annihilation with Dark Energy Survey Y3 LSBG sample

“…In our analysis, we consider the 6dFGS sample in the DES Y1 Gold footprint [30] for the dN/dz measurement and the redshift range of the sample is limited to z ≤ 0.15. This range would include redshifts of our LS-BGs because Hα-selected LSBG samples reside within a few hundreds Mpc [19,31]. As described in the DR3 report [29], we only use samples with the redshift-quality flag Q = 3, 4.…”