Bright Lyman-α emitters among Spitzer SMUVS galaxies in the MUSE/COSMOS field

Abstract

We search for the presence of bright Lyα emitters among Spitzer SMUVS galaxies at z > 2.9 making use of homogeneous MUSE spectroscopic data. Although these data only cover a small region of COSMOS, MUSE has the unique advantage of providing spectral information over the entire field, without the need of target pre-selection. This results in an unbiased detection of all the brightest Lyα emitters among the SMUVS sources, which by design are stellar-mass selected galaxies. Within the studied area, ∼ 14% of the SMUVS galaxies at z > 2.9 have Lyα fluxes F λ 7 × 10 −18 erg s −1 cm −2 . These Lyα emitters are characterized by three types of emission, 47% show a single line profile, 19% present a double peak or a blue bump and 31% show a red tail. One object (3%) shows both a blue bump and a red tail. We also investigate the spectral energy distribution (SED) properties of the SMUVS galaxies which are MUSE detected and which are not. After stellar-mass matching both populations, we find that the MUSE detected galaxies have generally lower extinction than SMUVS-only objects, while there is no clear intrinsic difference in the mass and age distributions of the two samples. For the MUSE-detected SMUVS galaxies, we compare the instantaneous SFR lower limit obtained from the Lyα line with its past average derived from SED fitting, and find evidence for rejuvenation in some of our oldest objects. In addition, we study the spectra of those Lyα emitters which are not detected in SMUVS in the same field. We find that the emission line profile shown are 67% a single line, 3% a blue bump and 20% a red tail profile. The difference in profile distribution could be ascribed to the fainter Lyα luminosities of the MUSE sources not detected in SMUVS and an intrinsically different mass distribution. Finally, we search for the presence of galaxy associations using the spectral redshifts. MUSE's integral coverage reveals that these associations are 20 times more likely than what is derived from all the other existing spectral data in COSMOS, which is biased by target pre-selection.

The Galaxy Starburst/Main-sequence Bimodality over Five Decades in Stellar Mass at z ≈ 3–6.5

“…In particular, ≈68% of our sources have E(B − V ) = 0.0 (Figure 3). We find that our values of E(B − V ) are in agreement with what has been measured in other populations of LAEs (e.g., Karman et al 2017;Rosani et al 2020).…”

The galaxy starburst/main-sequence bimodality over five decades in stellar mass at z ~ 3-6.5

“…3). We find that our values of E(B-V) are in agreement with what has been measured in other populations of LAEs (e.g., Karman et al 2017;Rosani et al 2020).…”

COSMOS2020: A Panchromatic View of the Universe to z ∼ 10 from Two Complementary Catalogs

“…The spectroscopic surveys presented below share a common system to define the confidence level in the redshift measurement (Lilly et al 2007;Le Fèvre et al 2015;Hasinger et al 2018;Kashino et al 2019;Masters et al 2019;Rosani et al 2019). They follow a flagging system described in Section 6 of Le Fèvre et al (2005).…”

“…The sample from Kashino et al (2019) contains 832 bright star-forming galaxies at z ∼ 1.6 with stellar masses M M log 9.5 10 sim ( )  > following the star-forming main sequence. Also adopted are 447 sources observed with MUSE at ESO/ VLT (Rosani et al 2020). The sample includes faint starforming galaxies at z < 1.5 and Lyα emitters at z > 3 and can be used to test the photo-z in a magnitude regime as faint as i > 26.…”