We present the results of a new study investigating the relationship between observed Ly alpha equivalent width (W-lambda(Ly alpha)) and the metallicity of the ionizing stellar population (Z(star)) for a sample of 768 star-forming galaxies at 3 <= z <= 5 drawn from the VANDELS survey. Dividing our sample into quartiles of rest-frame W-lambda(Ly alpha) across the range-58 angstrom less than or similar to W-lambda(Ly alpha) less than or similar to 110 angstrom, we determine Z(star) from full spectral fitting of composite far-ultraviolet spectra and find a clear anticorrelation between W-lambda(Ly alpha) and Z(star). Our results indicate that Z(star) decreases by a factor greater than or similar to 3 between the lowest W-lambda(Ly alpha) quartile (< W-lambda(Ly alpha)> = -18 angstrom) and the highest W-lambda(Ly alpha) quartile (< W-lambda(Ly alpha)> = 24 angstrom). Similarly, galaxies typically defined as Lyman alpha emitters (LAEs; W-lambda(Ly a) > 20 A) are, on average, metal poor with respect to the non-LAE galaxy population (W-lambda(Ly alpha) <= 20 angstrom) with Z(star non-LAE) greater than or similar to 2 x Z(star LAE). Finally, based on the best-fitting stellarmodels, we estimate that the increasing strength of the stellar ionizing spectrum towards lower Z(star) is responsible for similar or equal to 15-25 per cent of the observed variation in W-lambda(Ly alpha) across our sample, with the remaining contribution (similar or equal to 75-85 per cent) being due to a decrease in the HI/dust covering fractions in low-Z(star) galaxies.

Cullen, F., McLure, R.J., Dunlop, J.S., Carnall, A.C., McLeod, D.J., Shapley, A.E., et al. (2020). The VANDELS survey: a strong correlation between Ly α equivalent width and stellar metallicity at 3 ≤ z ≤ 5. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 495(1), 1501-1510 [10.1093/mnras/staa1260].

The VANDELS survey: a strong correlation between Ly α equivalent width and stellar metallicity at 3 ≤ z ≤ 5

Bolzonella, M;Cimatti, A
Membro del Collaboration Group
;
Cucciati, O;Pozzetti, L;Talia, M
Membro del Collaboration Group
;
Cresci, G;
2020

Abstract

We present the results of a new study investigating the relationship between observed Ly alpha equivalent width (W-lambda(Ly alpha)) and the metallicity of the ionizing stellar population (Z(star)) for a sample of 768 star-forming galaxies at 3 <= z <= 5 drawn from the VANDELS survey. Dividing our sample into quartiles of rest-frame W-lambda(Ly alpha) across the range-58 angstrom less than or similar to W-lambda(Ly alpha) less than or similar to 110 angstrom, we determine Z(star) from full spectral fitting of composite far-ultraviolet spectra and find a clear anticorrelation between W-lambda(Ly alpha) and Z(star). Our results indicate that Z(star) decreases by a factor greater than or similar to 3 between the lowest W-lambda(Ly alpha) quartile (< W-lambda(Ly alpha)> = -18 angstrom) and the highest W-lambda(Ly alpha) quartile (< W-lambda(Ly alpha)> = 24 angstrom). Similarly, galaxies typically defined as Lyman alpha emitters (LAEs; W-lambda(Ly a) > 20 A) are, on average, metal poor with respect to the non-LAE galaxy population (W-lambda(Ly alpha) <= 20 angstrom) with Z(star non-LAE) greater than or similar to 2 x Z(star LAE). Finally, based on the best-fitting stellarmodels, we estimate that the increasing strength of the stellar ionizing spectrum towards lower Z(star) is responsible for similar or equal to 15-25 per cent of the observed variation in W-lambda(Ly alpha) across our sample, with the remaining contribution (similar or equal to 75-85 per cent) being due to a decrease in the HI/dust covering fractions in low-Z(star) galaxies.
2020
Cullen, F., McLure, R.J., Dunlop, J.S., Carnall, A.C., McLeod, D.J., Shapley, A.E., et al. (2020). The VANDELS survey: a strong correlation between Ly α equivalent width and stellar metallicity at 3 ≤ z ≤ 5. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 495(1), 1501-1510 [10.1093/mnras/staa1260].
Cullen, F; McLure, RJ; Dunlop, JS; Carnall, AC; McLeod, DJ; Shapley, AE; Amorin, R; Bolzonella, M; Castellano, M; Cimatti, A; Cirasuolo, M; Cucciati, ...espandi
File in questo prodotto:
File Dimensione Formato  
11585_764375.pdf

accesso aperto

Tipo: Versione (PDF) editoriale
Licenza: Licenza per accesso libero gratuito
Dimensione 2.7 MB
Formato Adobe PDF
2.7 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/764375
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 28
  • ???jsp.display-item.citation.isi??? 26
social impact