A Tale of Three Galaxies: Anomalous Dust Properties in IRASF10398+1455, IRASF21013-0739 and SDSSJ0808+3948
arXiv:1407.0914 · doi:10.1088/2041-8205/794/2/L19
Abstract
On a galactic scale the 9.7um silicate emission is usually only seen in type 1 active galactic nuclei (AGNs). They usually also display a flat emission continuum at ~5--8um and the absence of polycyclic aromatic hydrocarbon (PAH) emission bands. In contrast, starburst galaxies, luminous infrared (IR) galaxies (LIRGs), and ultraluminous IR galaxies (ULIRGs) exhibit a red 5--8um emission continuum, strong 10um and 18um silicate absorption features, and strong PAH emission bands. Here we report the detection of anomalous dust properties by Spitzer/Infrared Spectrograph in three galaxies (IRASF10398+1455, IRASF21013-0739 and SDSSJ0808+3948) which are characterized by the simultaneous detection of a red 5--8um emission continuum, the 9.7 and 18um silicate emission features as well as strong PAH emission bands. These apparently contradictory dust IR emission properties are discussed in terms of iron-poor silicate composition, carbon dust deficit, small grain size and low dust temperature in the young AGN phase of these three galaxies.
accepted for publication in ApJL
References in corpus (9)
- Galaxy Groups in the SDSS DR4: I. The Catalogue and Basic Properties
- AGN Dusty Tori: I. Handling of Clumpy Media
- The distribution of silicate strength in Spitzer spectra of AGNs and ULIRGs
- The Diverse Properties of the Most Ultraviolet Luminous Galaxies Discovered by the Galaxy Evolution Explorer
- Silicates in Ultra-Luminous Infrared Galaxies
- Unobscured Type 2 AGNs
- The Origin of the Silicate Emission Features in the Seyfert 2 Galaxy, NGC 2110
- On the Crystallinity of Silicate Dust in the Interstellar Medium
- Dust in the wind: Crystalline silicates, corundum and periclase in PG 2112+059