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We present a 24 μ m-selected spectroscopic sample z > 0.13 (median 〈 z 〉 = 0.41) in the Lockman Hole field, consisting of 4035 spectra. Our aim is to identify active galactic nuclei (AGNs) and determine their fraction in this mid-infrared-selected sample. In this work, we use the [Ne v ] λ 3426 emission line to spectroscopically identify AGNs. Combined with broad-line Type I AGNs selected in our previous study, our sample consists of 887 (∼22%) spectroscopically confirmed AGNs. We perform a stacking analysis on the remaining spectra and find that in various mid-infrared (MIR) wedge-selected AGN candidates, the stacked spectra still show significant [Ne v ] λ 3426 emission. In contrast, no clear [Ne v ] λ 3426 signal is detected in non-AGN candidates falling outside the wedges. Assuming a range of AGN MIR spectral energy distribution (SED) slope of −0.3 < α < 0.7, and an average star-forming relation derived from 65 star-forming templates, we develop a robust method to separate the AGN and star-forming contributions to the MIR SEDs using the rest-frame L _12 / L _1.6 versus L _4.5 / L _1.6 diagram. We separate the objects into bins of L _12 and find that the AGN fraction increases with increasing L _12 . We also find that the stacked [Ne v ] λ 3426 strength scales with L _12 . The pure AGN luminosity at 12 μ m exhibits a positive correlation with the star formation rates, indicating possible coevolution and common gas supply between the AGNs and their host galaxies. Varying population properties across the redshift range explored contribute to the observed correlation.

We present a sample of 330 blue edge-on low surface brightness galaxies (ELSBGs). To understand the chemical evolution of ELSBGs, we derived the gas-phase abundance and the [ α /Fe] ratio. Compared with star-forming galaxies, ELSBGs show a flatter trend in the mass–metallicity ( M _* – Z ) relation, which suggests that the oxygen abundance enhancement is inefficient. We focused on 77 ELSBGs with H i data and found that the closed-box model cannot explain their gas fraction and metallicity relation, which implies that infall and/or outflow is needed. We derived the [ α /Fe] ratio of normal ELSBG ( = 10 ^9.5 M _⊙ ) using single stellar population grids from the MILES stellar library. The mean [ α /Fe] ratios are 0.18 and 0.4 for normal ELSBG and massive ELSBG, respectively. We suggest that the long timescales of star formation and/or metal-rich gas outflow events caused by SNe Ia winds are likely to be responsible for the α -enhancement of massive ELSBGs.

We present a sample of 330 blue edge-on low surface brightness galaxies (ELSBGs). To understand the chemical evolution of ELSBGs, we derived the gas-phase abundance and the [ α /Fe] ratio. Compared with star-forming galaxies, ELSBGs show a flatter trend in the mass–metallicity (M *– Z) relation, which suggests that the oxygen abundance enhancement is inefficient. We focused on 77 ELSBGs with H i data and found that the closed-box model cannot explain their gas fraction and metallicity relation, which implies that infall and/or outflow is needed. We derived the [ α /Fe] ratio of normal ELSBG (<109.5 M ⊙) and massive ELSBG (> = 109.5 M ⊙) using single stellar population grids from the MILES stellar library. The mean [ α /Fe] ratios are 0.18 and 0.4 for normal ELSBG and massive ELSBG, respectively. We suggest that the long timescales of star formation and/or metal-rich gas outflow events caused by SNe Ia winds are likely to be responsible for the α -enhancement of massive ELSBGs. [ABSTRACT FROM AUTHOR]

We demonstrate a diode-pumped passively cw mode-locked Nd:CaGdAlO4 laser operating at 1079nm with a semiconductor saturable absorber mirror for the first time to the best of our knowledge. The threshold pump power of the laser is 180mW. A maximum average output power of 93mW is obtained under the pump power of 1.94 W. The pulse duration of the mode-locked pulses is 3.1 ps and the repetition rate is 157 MHz. [ABSTRACT FROM AUTHOR]

A diode-pumped passively mode-locked Nd-doped La3Ga5SiO14 (Nd:LGS) laser is realized by using a semiconductor saturable absorber mirror. With the pump power of 2 W, we obtain a 532 nm self-frequency doubling (SFD) laser together with a 10.9 ps fundamental laser at the repetition rate of 173.7 MHz. To the best of our knowledge, it is the first time for self-frequency doubling in the diode-pumped mode-locked Nd:LGS laser. Benefited from the diode lasers and its self-frequency doubling property, Nd:LGS could be a potential candidate for compact, stable and cheap ultrafast green laser sources. [ABSTRACT FROM AUTHOR]