TY - JOUR

T1 - The JWST Emission Line Survey (JELS)

T2 - an untargeted search for H α emission line galaxies at z > 6 and their physical properties

AU - Pirie, C A

AU - Best, P N

AU - Duncan, K J

AU - McLeod, D J

AU - Cochrane, R K

AU - Clausen, M

AU - Dunlop, J S

AU - Flury, S R

AU - Geach, J E

AU - Hale, C L

AU - Ibar, E

AU - Kondapally, R

AU - Li, Zefeng

AU - Matthee, J

AU - McLure, R J

AU - Ossa-Fuentes, L

AU - Patrick, A L

AU - Smail, Ian

AU - Sobral, D

AU - Stephenson, H M O

AU - Stott, J P

AU - Swinbank, A M

PY - 2025/8/1

Y1 - 2025/8/1

N2 - We present the first results of the JWST Emission Line Survey (JELS). Utilizing the first NIRCam narrow-band imaging at 4.7 μm, o v er 63 arcmin 2 in the PRIMER/COSMOS field, we have identified 609 emission line galaxy candidates. From these, we robustly selected 35 H α star-forming galaxies at z ∼ 6 . 1, with H α star-formation rates ( SFR Hα) of ∼ 0.9 − 15 M ☉ yr −1 . Combining our unique H α sample with the exquisite panchromatic data in the field, we explored their physical properties and star-formation histories, and compared these to a broad-band selected sample at z ∼ 6 which has offered vital new insights into the nature of high-redshift galaxies. UV-continuum slopes ( β) were considerably redder for our H α sample ( β ∼−1 . 92) compared to the broad-band sample ( β ∼−2 . 35). This was not due to dust attenuation as our H α sample was relatively dust- poor (median A V = 0 . 23); instead, we argue that the reddened slopes could be due to nebular continuum. We compared SFR Hα and the UV-continuum-derived SFR UV to SED-fitted measurements av eraged o v er canonical time-scales of 10 and 100 Myr ( SFR 10 and SFR 100 ). We found an increase in recent SFR for our sample of H α emitters, particularly at lower stellar masses ( < 10 9 M ☉ ). We also found that SFR Hα strongly traces SFR averaged over 10 Myr time-scales, whereas the UV-continuum o v erpredicts SFR on 100 Myr time-scales at low stellar masses. These results point to our H α sample undergoing ‘bursty’ star formation. Our F356W z ∼ 6 sample showed a larger scatter in SFR 10 / SFR 100 across all stellar masses, which has highlighted ho w narro w-band photometric selections of H α emitters are key to quantifying the burstiness of star-formation activity.

AB - We present the first results of the JWST Emission Line Survey (JELS). Utilizing the first NIRCam narrow-band imaging at 4.7 μm, o v er 63 arcmin 2 in the PRIMER/COSMOS field, we have identified 609 emission line galaxy candidates. From these, we robustly selected 35 H α star-forming galaxies at z ∼ 6 . 1, with H α star-formation rates ( SFR Hα) of ∼ 0.9 − 15 M ☉ yr −1 . Combining our unique H α sample with the exquisite panchromatic data in the field, we explored their physical properties and star-formation histories, and compared these to a broad-band selected sample at z ∼ 6 which has offered vital new insights into the nature of high-redshift galaxies. UV-continuum slopes ( β) were considerably redder for our H α sample ( β ∼−1 . 92) compared to the broad-band sample ( β ∼−2 . 35). This was not due to dust attenuation as our H α sample was relatively dust- poor (median A V = 0 . 23); instead, we argue that the reddened slopes could be due to nebular continuum. We compared SFR Hα and the UV-continuum-derived SFR UV to SED-fitted measurements av eraged o v er canonical time-scales of 10 and 100 Myr ( SFR 10 and SFR 100 ). We found an increase in recent SFR for our sample of H α emitters, particularly at lower stellar masses ( < 10 9 M ☉ ). We also found that SFR Hα strongly traces SFR averaged over 10 Myr time-scales, whereas the UV-continuum o v erpredicts SFR on 100 Myr time-scales at low stellar masses. These results point to our H α sample undergoing ‘bursty’ star formation. Our F356W z ∼ 6 sample showed a larger scatter in SFR 10 / SFR 100 across all stellar masses, which has highlighted ho w narro w-band photometric selections of H α emitters are key to quantifying the burstiness of star-formation activity.

KW - galaxies: high-redshift

KW - surveys

KW - galaxies: emission lines

KW - galaxies: star formation

KW - galaxies: evolution

KW - reionization

U2 - 10.1093/mnras/staf1006

DO - 10.1093/mnras/staf1006

M3 - Journal article

VL - 541

SP - 1348

EP - 1376

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

ER -