Cold Dust in Late‐Type Virgo Cluster Galaxies

Abstract

We have statistically analyzed the spatially integrated far-infrared (FIR) emissions of the complete volume-and luminosity-limited sample of late-type (later than S0) Virgo Cluster galaxies measured using the Infrared Space Observatory by Tu †s and coworkers in bands centered on 60, 100, and 170 km. Thirty of 38 galaxies detected at all three wavelengths contain a cold dust emission component, present within all morphological types of late-type systems ranging from early giant spiral galaxies to blue compact dwarfs (BCDs) and which could not have been recognized by IRAS. We Ðtted the data with a superposition of two modiÐed blackbody functions, physically identiÐed with a localized warm dust emission component associated with H II regions (whose temperature was constrained to be 47 K), and a di †use emission component of cold dust. The cold dust temperatures were found to be broadly distributed, with a median of 18 K, some 8È10 K lower than would have been predicted from IRAS. The derived total dust mass is correspondingly increased by factors of typically 6È13. A good linear correlation is found between the "" warm FIR ÏÏ luminosities and the Ha equivalent widths (EWs), supporting the assumptions of our constrained spectral energy distribution Ðt procedure. We also found a good nonlinear correlation between the "" cold FIR ÏÏ luminosities and the Ha EWs, consistent with the prediction of Popescu and coworkers that the FIR-submillimeter emission should mainly be due to di †use nonionizing UV photons. Both the "" warm ÏÏ and the "" cold ÏÏ FIR luminosity components are nonlinearly correlated with the (predominantly nonthermal) radio luminosities. There is a tendency for the temperatures of the cold dust component to become colder and for the cold dust surface densities (normalized to optical area) to increase for later morphological types. A particularly signiÐcant result concerns the low dust temperatures (ranging down to less than 10 K) and large dust masses associated with the Im and BCD galaxies in our sample. We propose two scenarios to account for the FIR characteristics of these systems.

TheHerschelVirgo Cluster Survey

“…3 (plus signs), and are about one order of magnitude smaller than those of the Virgo dwarfs with a similar metal abundance. Finally, six Im-BCD galaxies in Virgo analysed with ISO data by Popescu et al (2002) show similar properties to the dwarfs in the current work.…”

“…This cold dust component may either be associated with the star-forming regions, residing in clumpy molecular complexes (Galliano et al 2003), or extend beyond the optical disc following the distribution of the neutral hydrogen (Hi, Popescu et al 2002). However, the main objection to this interpretation is the high dust mass associated with the cold dust, and alternative explanations have been proposed (see Bendo et al 2010, and references therein).…”

The effects of dust on the photometric parameters of decomposed disks and bulges

“…It is already known that spiral galaxies contain large amounts of dust (Stickel et al 2000(Stickel et al , 2004Tuffs et al 2002;Popescu et al 2002;Vlahakis et al 2005;Driver et al 2007;Dariush et al 2011;Rowlands et al 2012;Bourne et al 2012;Dale et al 2012;Grootes et al 2013a), and that this dust changes the appearance of disks and bulges from what would be predicted based solely on their intrinsic stellar distributions (e.g. Tuffs et al 2004;Möllenhoff et al 2006;Gadotti et al 2010;Pastrav et al 2013).…”

The dust SED of dwarf galaxies

“…Melisse & Israel 1994) or of cold FIR SEDs (as revealed by ISO and Herschel measurements extending longwards of 100 μm -e.g. Popescu et al 2002;Grossi et al 2010). Such variety may not be too surprising given that the SF in dwarf galaxies is likely to be fundamentally bursty in nature.…”

“…Other factors potentially contributing to the observed variety in FIR colours are differences in the contribution of very small grains (e.g. Galliano et al 2003Galliano et al , 2005 and the possible presence of extended cold dust outside the main star forming disk of the galaxy (Popescu et al 2002).…”