IRAS galaxies

The IRAS galaxies provided some of the earliest evidence from redshift surveys, and from source counts as a function of observed flux, that the spiral galaxy population has undergone evolution (ORS see Fig. 12.2). This result is analogous to similar evidence from source counts of radio galaxies and quasars, as well as quasar redshifts, and a correlation that has been observed between radio and infrared luminosity suggests that the evolution could be similar in both cases. Typical simple models for such evolution include luminosity evolution according to... 

As part of a program to determine the near-IR photometric and spectroscopic properties of bright IRAS galaxies, we have obtained JHK images and medium resolution (A/AA 330) JT-band spectra of VV114. 

The IRAS satellite mission, launched in 1983, provided a more complete survey of disk and active galaxies containing dust than had been possible from optical observations. Follow-up measurements of redshifts and other properties led to significant results for cosmology and the discovery of many luminous star-forming and active galaxies enshrouded by dust. A typical spiral galaxy like our own... 

A 1.45 GHz Atlas of the IRAS bright galaxy sample [9]. Conditions Xray flux > 100 mJy, redshift< 0.3, and magnitude > 16... 

Extra galactic sources like m82 may be seen out to TOMpc, thus beyond the local group. The volume of space sampled for active galaxies is considerable. One may speculate about detection of "infrared galaxies, when they exist, there is a good chance that IRAS will discover a reasonably large sample of them. 

Fig. 7.15 Color composite image of ultra-luminous infrared galaxy IRAS...

We have observed 11 galaxies in the J (1.25 on), H (1.65 ), and K (2.2/um) bands from the IRAS Bri t Galaxy Sample (BGS) (Soifer 1989) and the Warm Galaxy Sample (WGS) (Sanders 1989) using an infrared camera employing a 58x62 pixel INSb photodiode array at the f/70 Cassegrain focus of the Palomar 5m Hale tdescope. 

Three galaxies, Mrk 231, IRAS 05189-2524, and IRAS 07598-1-6508, possess optically active nudei (Seyfert or LINER types) and show evidence in the near-infrared of a circumnudear starburst. On physical scales of 4kpc these galaxies have very red near-infrared colors, with H-K >0.8. These... 

We find four galaxies without direct evidence of an optical broad line region (Se3rfert 2, LINER, or HE region type nuclei) to have very red J-H and H-K colors in our smallest apertures (t3rpicaUy 1 arcsecond diameter) which may indicate the presence of dust-enshrouded active nuclei. These are IRAS 05189-2524, IRAS 12071-0444, UGC 5101, wd IRAS 08572-1-3915. 

In contrast, the Seyfert 1 galaxy Mk 1239 appears unresolved at 10.3. The measured fiux density of 0.63 Jy is in excellent agreement with the IRAS value and a canonical spectral shape, indicating a dominance of the active nucleus and no contribution from an extranuclear source. Properties of the complete sample will be discussed in a separate publication. 

Abstract. We have searched for ledshifted optical emission lines in the neai-in aied om 17 distant radio galaxies (and the IRAS source FSC 10214+4724, Elston et al. 1993), using InSb array spectrometers at the KPNO and CTIO 4m telescopes. The redshifts range from 0.8 to 3.4. We detect lines in over a dozen cases, summarized in the table below. 

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