TY - JOUR
T1 - UV-continuum β slopes of individual z ∼2-6 clumps and their evolution
AU - Bolamperti, A.
AU - Zanella, A.
AU - Meštrić, U.
AU - Vanzella, E.
AU - Castellano, M.
AU - Bergamini, P.
AU - Calura, F.
AU - Grillo, C.
AU - Meneghetti, M.
AU - Mercurio, A.
AU - Rosati, P.
AU - Devereaux, T.
AU - Iani, E.
AU - Vernet, J.
N1 - Publisher Copyright:
© 2023 The Author(s).
PY - 2023/12
Y1 - 2023/12
N2 - We study the ultraviolet (UV) continuum βslope of a sample of 166 clumps, individual star-forming regions observed in high- redshift galaxies. They are hosted by 67 galaxies with redshift between 2 and 6.2, strongly lensed by the Hubble Frontier Fields cluster of galaxies MACS J0416.1 −2403. The βslope is sensitive to a variety of physical properties, such as the metallicity, the age of the stellar population, the dust attenuation throughout the galaxy, the stellar initial mass function (IMF), and the star formation history (SFH). The aim of this study is to compare the β-values of individual clumps with those measured on the entire galaxy, to investigate possible physical differences between these regions and their hosts. We found a median value of β∼−2.4, lower than that of integrated galaxies. This result confirms that clumps are sites of intense star formation, populated by young, massive stars, whose spectrum strongly emits in the UV. This is also consistent with the assumption that the dust extinction at the location of the clumps is lower than the av erage e xtinction of the galaxy, or that clumps have a different IMF or SFH. We made use of the correlations, disco v ered for high-redshift galaxies, of the β-value with those of redshift and UV magnitude, M UV, finding that clumps follow the same relations, extended to much fainter magnitudes ( M UV < −13). We also find evidence of eight clumps with extremely blue ( β ≲−2.7) slopes, which could be the signpost of low-metallicity stars and constrain the emissivity of ionizing photons at high redshift.
AB - We study the ultraviolet (UV) continuum βslope of a sample of 166 clumps, individual star-forming regions observed in high- redshift galaxies. They are hosted by 67 galaxies with redshift between 2 and 6.2, strongly lensed by the Hubble Frontier Fields cluster of galaxies MACS J0416.1 −2403. The βslope is sensitive to a variety of physical properties, such as the metallicity, the age of the stellar population, the dust attenuation throughout the galaxy, the stellar initial mass function (IMF), and the star formation history (SFH). The aim of this study is to compare the β-values of individual clumps with those measured on the entire galaxy, to investigate possible physical differences between these regions and their hosts. We found a median value of β∼−2.4, lower than that of integrated galaxies. This result confirms that clumps are sites of intense star formation, populated by young, massive stars, whose spectrum strongly emits in the UV. This is also consistent with the assumption that the dust extinction at the location of the clumps is lower than the av erage e xtinction of the galaxy, or that clumps have a different IMF or SFH. We made use of the correlations, disco v ered for high-redshift galaxies, of the β-value with those of redshift and UV magnitude, M UV, finding that clumps follow the same relations, extended to much fainter magnitudes ( M UV < −13). We also find evidence of eight clumps with extremely blue ( β ≲−2.7) slopes, which could be the signpost of low-metallicity stars and constrain the emissivity of ionizing photons at high redshift.
KW - galaxies: evolution
KW - galaxies: high-redshift
UR - http://www.scopus.com/inward/record.url?scp=85176382514&partnerID=8YFLogxK
U2 - 10.1093/mnras/stad3114
DO - 10.1093/mnras/stad3114
M3 - Article
AN - SCOPUS:85176382514
SN - 0035-8711
VL - 526
SP - 5263
EP - 5277
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -