The AMIGA sample of isolated galaxies. XIII. The HI content of an almost "nurture free" sample

M. G. Jones, D. Espada, L. Verdes-Montenegro, W. K. Huchtmeier, U. Lisenfeld, S. Leon, J. Sulentic, J. Sabater, D. E. Jones, Susana Sanchez-Exposito, J. Garrido

Research output: Contribution to journalArticlepeer-review

Abstract

We present the largest catalogue of HI single dish observationsof isolated galaxies to date, as part of the multi-wavelengthcompilation being performed by the AMIGA project (Analysis of theinterstellar Medium in Isolated GAlaxies). Despite numerous studies ofthe HI content of galaxies, no revision focused on the HI scalingrelations of the most isolated L∗ galaxies has beenmade since Haynes & Giovanelli (1984, AJ, 89, 758). Aims: TheAMIGA sample has been demonstrated to be almost "nurture free",therefore, by creating scaling relations for the HI content of thesegalaxies we will define a metric of HI normalcy in the absence ofinteractions. Methods: The catalogue comprises of our own HIobservations with Arecibo, Effelsberg, Nançay and GBT, andspectra collected from the literature. In total we have measurements orconstraints on the HI masses of 844 galaxies from the Catalogue ofIsolated Galaxies (CIG). The multi-wavelength AMIGA dataset includes arevision of the B-band luminosities (LB), optical diameters(D25), morphologies, and isolation. Due to the large size ofthe catalogue, these revisions permit cuts to be made to ensureisolation and a high level of completeness, which was not previouslypossible. With this refined dataset we fit HI scaling relations based onluminosity, optical diameter and morphology. Our regression modelincorporates all the data, including upper limits, and accounts foruncertainties in both variables, as well as distance uncertainties. Results: The scaling relation of HI mass with D25 is ingood agreement with that of Haynes & Giovanelli (1984), but ourrelation with LB is considerably steeper. This disagreementis attributed to the large uncertainties in the luminosities, whichintroduce a bias when fitting with ordinary least squares regression (aswas done in previous works), and the different morphology distributionsof the samples. We find that the main effect of morphology on theD25-relation is to increase the intercept towards latertypes, while for the LB-relation it is to flatten the slope.These trends were not evident in previous works due to the small numberof detected early-type galaxies. Applying our relations to HI detectedgalaxies in the Virgo cluster we find that although the typicalHI-deficiency is only 0.3 dex, the tail of the distribution extendsover an order of magnitude beyond that of the AMIGA sample. Theseresults are in general agreement with previous studies of HI-deficiencyin the Virgo cluster. Conclusions: The HI scaling relations ofthe AMIGA sample define an up-to-date metric of the HI content of almost"nurture free" galaxies. These relations allow the expected HI mass, inthe absence of interactions, of an individual galaxy to be predicted towithin 0.25 dex (for typical measurement uncertainties). These relationsare thus suitable for use as statistical measures of the impact ofinteractions on the neutral gas content of galaxies.
Original languageEnglish
Number of pages29
JournalAstronomy & Astrophysics
Volume609
Early online date22 Dec 2017
DOIs
Publication statusPublished - 1 Jan 2018

Keywords

  • galaxies: evolution
  • galaxies: interactions
  • radio lines: ISM
  • surveys

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