Correlations between H α equivalent width and galaxy properties at z = 0.47: Physical or selection-driven?
| Autor: | Alistair R. Walker, L. F. Barrientos, Isak Wold, Alicia Coughlin, James E. Rhoads, Leopoldo Infante, Ali Ahmad Khostovan, Weida Hu, S. Malhotra, Jun Xian Wang, Zhen-Ya Zheng, F. Valdes, Lucia A. Perez, John Pharo, Santosh Harish, C. Jiang |
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| Rok vydání: | 2021 |
| Předmět: |
Physics
Stellar mass 010308 nuclear & particles physics Star formation Astronomy and Astrophysics Astrophysics Astrophysics - Astrophysics of Galaxies 01 natural sciences Galaxy Distribution (mathematics) Space and Planetary Science 0103 physical sciences Probability distribution 010303 astronomy & astrophysics Equivalent width Reionization Selection (genetic algorithm) |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 503:5115-5133 |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | The H$\alpha$ equivalent width (EW) is an observational proxy for specific star formation rate (sSFR) and a tracer of episodic star-formation activity. Previous assessments show that EW strongly anti-correlates with stellar mass as $M^{-0.25}$ similar to the sSFR -- stellar mass relation. However, such a correlation may be driven/formed by selection effects. In this study, we investigate how H$\alpha$ EWs correlate with galaxy properties and how selection biases could alter such correlations using a $z = 0.47$ narrowband-selected sample of 1572 H$\alpha$ emitters from the Ly$\alpha$ Galaxies in the Epoch of Reionization (LAGER) survey. The sample covers 3 deg$^2$ of COSMOS and $1.1\times10^5$ cMpc$^3$. We assume an intrinsic EW distribution to form mock samples of H$\alpha$ emitters (HAEs) and propagate the selection criteria to match observations, giving us control on how selection biases can affect the underlying results. We find EW intrinsically correlates with stellar mass as $W_0 \propto M^{-0.16\pm0.03}$ and decreases by a factor of $\sim 3$ from $10^{7}$ to $10^{10}$ M$_\odot$. We find low-mass HAEs to be $\sim 320$ times more likely to have rest-frame EW$ > 200$\AA compared to high-mass HAEs. Combining the intrinsic EW -- stellar mass correlation with an observed SMF correctly reproduces the observed H$\alpha$ LF, while not correcting for selection effects underestimates the number of bright HAEs. This suggests that the intrinsic EW -- stellar mass correlation is physically significant and reproduces three statistical distributions of galaxy populations (LF, SMF, EW distribution). At lower masses, we find there are more high-EW outliers compared to high masses, even after taking into account selection effects. Our results suggest that high sSFR outliers indicative of bursty SF activity are intrinsically more prevalent in low-mass HAEs and not a byproduct of selection effects. Comment: 21 Pages, 13 Figures, 2 Tables, accepted to MNRAS |
| Databáze: | OpenAIRE |
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