We use 16μm, Spitzer-Infrared Spectrograph, blue peak-up photometry of 50 early-type galaxies in the Coma cluster to define the mid-infrared colour-magnitude relation. We compare with recent simple stellar population models that include the mid-infrared emission from the extended, dusty envelopes of evolved stars. The Ks-[16] colour in these models is very sensitive to the relative population of dusty asymptotic giant branch stars. We find that the passively evolving early-type galaxies define a sequence of approximately constant age (~10 Gyr) with varying metallicity. Several galaxies that lie on the optical/near-infrared colour-magnitude relation do not lie on the mid-infrared relation. This illustrates the sensitivity of the Ks-[16] colour to age. The fact that a colour-magnitude relation is seen in the mid-infrared underlines the extremely passive nature of the majority (68 per cent) of early-type galaxies in the Coma cluster. The corollary of this is that 32 per cent of the early-type galaxies in our sample are not `passive', insofar as they are either significantly younger than 10 Gyr or they have had some rejuvenation episode within the last few Gyr.

The mid-infrared colour-magnitude relation of early-type galaxies in the Coma cluster as measured by Spitzer-IRS / Clemens, M. S.; Bressan, A.; Panuzzo, P.; Rampazzo, R.; Silva, L.; Buson, L.; Granato, G. L.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 392:3(2009), pp. 982-991. [10.1111/j.1365-2966.2008.14080.x]

The mid-infrared colour-magnitude relation of early-type galaxies in the Coma cluster as measured by Spitzer-IRS

Bressan, A.;
2009-01-01

Abstract

We use 16μm, Spitzer-Infrared Spectrograph, blue peak-up photometry of 50 early-type galaxies in the Coma cluster to define the mid-infrared colour-magnitude relation. We compare with recent simple stellar population models that include the mid-infrared emission from the extended, dusty envelopes of evolved stars. The Ks-[16] colour in these models is very sensitive to the relative population of dusty asymptotic giant branch stars. We find that the passively evolving early-type galaxies define a sequence of approximately constant age (~10 Gyr) with varying metallicity. Several galaxies that lie on the optical/near-infrared colour-magnitude relation do not lie on the mid-infrared relation. This illustrates the sensitivity of the Ks-[16] colour to age. The fact that a colour-magnitude relation is seen in the mid-infrared underlines the extremely passive nature of the majority (68 per cent) of early-type galaxies in the Coma cluster. The corollary of this is that 32 per cent of the early-type galaxies in our sample are not `passive', insofar as they are either significantly younger than 10 Gyr or they have had some rejuvenation episode within the last few Gyr.
2009
392
3
982
991
https://arxiv.org/abs/0808.2899
Clemens, M. S.; Bressan, A.; Panuzzo, P.; Rampazzo, R.; Silva, L.; Buson, L.; Granato, G. L.
File in questo prodotto:
File Dimensione Formato  
clemens08_a.pdf

accesso aperto

Tipologia: Versione Editoriale (PDF)
Licenza: Non specificato
Dimensione 868.05 kB
Formato Adobe PDF
868.05 kB 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/20.500.11767/16846
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 32
  • ???jsp.display-item.citation.isi??? 32
social impact