[Paper Review] 1.65 micrometers (H-band) surface photometry of galaxies. IV:observations of 170 galaxies with the Calar Alto 2.2m telescope

A. Boselli, G. Gavazzi+3 more|ArXiv.org|Nov 22, 1999

Astronomy and Astrophysical Research19 citations

TL;DR

This study presents H-band (1.65 μm) surface photometry of 170 nearby galaxies, primarily from the Virgo, A262, Cancer, and Coma/A1367 supercluster regions, using the Calar Alto 2.2m telescope with the MAGIC infrared camera. It derives key structural parameters—total and optical-radius magnitudes, isophotal radii at 20.5 mag arcsec⁻², and concentration index C₃₁—contributing to a nearly complete near-infrared survey of late-type Virgo cluster galaxies with mₚ ≤ 16.0.

ABSTRACT

We present near-infrared (H band) surface photometry of 170 galaxies, obtained in 1997 using the Calar Alto 2.2m telescope equipped with the NICMOS3 camera MAGIC. The majority of our targets are selected among bright members of the Virgo cluster, however galaxies in the A262 and Cancer clusters and in the Coma/A1367 supercluster are also included. This data set is aimed at complementing the NIR survey in the Virgo cluster discussed in Boselli et al. (1997) and in the Coma Supercluster, presented in Papers I, II and III of this series. Magnitudes at the optical radius, total magnitudes, isophotal radii and light concentration indices are derived. (Tables 1 and 2 are only available in electronic form upon request to [e-mail])

Motivation & Objective

• To complete a comprehensive near-infrared (H-band) photometric survey of galaxies in the Virgo cluster and surrounding supercluster regions.
• To measure fundamental structural parameters—total magnitude, optical-radius magnitude, isophotal radius, and concentration index—for a large sample of galaxies.
• To ensure high completeness for late-type galaxies in the Virgo cluster, particularly those selected for ISO observations.
• To provide consistent, deep H-band data to support multiwavelength studies of galaxy structure and evolution.
• To integrate with prior surveys (Papers I–III, B97) to form a nearly complete NIR dataset for galaxies in the Coma supercluster and Virgo cluster.

Proposed method

• Acquired deep H-band (1.65 μm) imaging using the MAGIC 256×256 pixel NICMOS3 array on the Calar Alto 2.2m telescope.
• Employed mosaicing techniques to overcome sky background variations and achieve deep surface brightness limits, reaching down to ~26.5 mag arcsec⁻².
• Measured isophotal radii at the 20.5 mag arcsec⁻² isophote (rH(20.5)) to ensure consistency with prior surveys.
• Calculated total H magnitudes (HT) by extrapolating elliptical isophotal fluxes using combined exponential and de Vaucouleurs laws.
• Computed H-band magnitudes at the optical radius (HB25) via extrapolation from circular aperture measurements using standard growth curves.
• Defined the concentration index C₃₁ as a bulge-sensitive parameter independent of bulge-disk decomposition, using flux ratios within 3 and 1 scale lengths.

Experimental results

Research questions

• RQ1 What is the structural distribution of H-band light in a large, representative sample of nearby galaxies across multiple clusters?
• RQ2 How do H-band isophotal radii (rH(20.5)) compare to optical B-band radii (rB) measured at fainter isophotes in the VCC?
• RQ3 To what extent do H-band total magnitudes (HT) and magnitudes at the optical radius (HB25) differ, and what does this imply for luminosity estimates?
• RQ4 Is there a correlation between H-band concentration index C₃₁ and absolute H-band luminosity, and what does it reveal about bulge content in galaxies?
• RQ5 How complete is the H-band survey for late-type Virgo cluster galaxies with mₚ ≤ 16.0, particularly those selected for ISO observations?

Key findings

• The survey achieved 97% completeness for 625 out of 646 Coma supercluster galaxies (mₚ ≤ 15.7) with radial velocities between 5000 and 8000 km s⁻¹.
• 89% completeness was achieved for 221 out of 248 Virgo Cluster Catalogue (VCC) galaxies with mₚ ≤ 14.0, and 100% completeness for 88 late-type VCC galaxies with mₚ ≤ 16.0 selected for ISO observations.
• The average difference between total H-band magnitude (HT) and H-band magnitude at the optical radius (HB25) is 0.05 ± 0.15 mag, with HT being brighter.
• The relation rH(20.5) = 0.7 × rB(25.0) does not hold for this sample, as optical radii are measured at fainter isophotes (faintest detectable), leading to larger rB values.
• A clear correlation exists between H-band concentration index C₃₁ and absolute H-band luminosity, with higher C₃₁ values (indicating more prominent bulges) found predominantly in high-luminosity systems.
• High C₃₁ values (>2.8) are rare among late-type spirals, confirming that high luminosity does not imply a significant bulge component.