arXiv subjects

Asmus Boehm

Publications and source records attributed to Asmus Boehm.

21 records · Page 2Linked to original sources

arXiv2004

The Evolution of Field Spiral Galaxies over the Past 8 Gyr

We have performed a large observing campaign of intermediate-redshift disk galaxies including spectroscopy with the FORS instruments of the VLT and imaging with the Advanced Camera for Surveys onboard the HST. Our data set comprises 113 late-type galaxies in the redshift range 0.1 2mag in rest-frame B. This evolution would be at variance with the predictions from numerical simulations. On the other hand, the disks of the distant galaxies are, for a given Vmax, slightly smaller than those of their local counterparts, as expected for a hierarchical structure growth. Hence, the discrepancy between the observations and theoretical predictions would be limited to the properties of the stellar populations. A possible explanation could be the suppression of star formation in low-mass disks which is not yet properly implemented in models of galaxy evolution. (abridged)

astro-ph↗

arXiv2004

Disk galaxy evolution up to redshift z=1

We have performed intermediate-resolution VLT/FORS spectroscopy and HST/ACS imaging of 129 field spiral galaxies within the FORS Deep Field. The galaxies cover the redshift range 0.1 < z < 1.0 and comprise all types from Sa to Sdm/Im. Spatially resolved rotation curves were extracted and fitted with synthetic velocity fields that take into account all geometric (e.g., inclination and misalignment) and observational effects (in particular, blurring due to optical beam smearing and seeing). Using these fits, the maximum rotation velocity Vmax could be determined for 73 objects. The Tully-Fisher relation of this sample at a mean look-back time of ~5Gyr shows a luminosity evolution which amounts to ~2mag in rest-frame B for low-mass spirals (Vmax~100km/s) but is negligible for high-mass spirals (Vmax~300km/s). This confirms our previous analysis which was limited to ground-based imaging. The observed overluminosity of low-mass galaxies is at variance with predictions from simulations. On the other hand, at given Vmax, we find slightly smaller disk sizes towards higher redshifts, in compliance with the CDM hierarchical model. The observed mass-dependent luminosity evolution might therefore point towards the need for a more realistic modelling of the stellar (i.e. baryonic) component in N-body codes.

astro-ph↗

arXiv2004

Quantitative interpretation of the rotation curves of spiral galaxies at redshifts z~0.7 and z~1

We present decompositions of the rotation curves of three spiral galaxies at redshifts z~0.7 and 1 into contributions by their bulges, disks, and dark halos, respectively. In order to set constraints on the degeneracy of the decompositions we interpret the morphology of the spiral structures quantitatively in the framework of density wave theory. Galaxy models constrained in such a way show that the distant galaxies, which are much younger than nearby galaxies, have very likely 'maximum disks', i.e. are dominated in their inner parts by baryonic matter. We argue that current theories of the cosmogony of galaxies must allow for these types of galaxies.

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