Abstract
Context. Slitless spectroscopy has long been considered a complicated and confused technique. Nonetheless, with the advent of Hubble Space Telescope (HST) instruments, characterized by a low sky background level and a high spatial resolution (most notably WFC3), slitless spectroscopy has become an adopted survey tool to study galaxy evolution from space. Aims. We aim to investigate its application to single-object studies to measure not only redshift and integrated spectral features, but also spatially-resolved quantities such as galaxy kinematics. Methods. We built a complete forward model to quantitatively compare actual slitless observations. This model depends on a simplified thin cold disk galaxy description – including flux-distribution, intrinsic-spectrum, and kinematic parameters – and on the instrumental signature. It is used to improve redshifts and constrain basic rotation curve parameters, meaning the plateau velocity v0 (in km s−1) and the central velocity gradient w0 (in km s−1 arcsec−1). Results. The model is tested on selected observations from 3D-HST and GLASS surveys to estimate redshift and kinematic parameters on several galaxies measured with one or more roll angles. Conclusions. Our forward approach makes it possible to mitigate the self-contamination effect, a primary drawback of slitless spectroscopy, and therefore has the potential to increase precision on redshifts. In a limited sample of well-resolved spiral galaxies from HST surveys, it is possible to significantly constrain galaxy rotation curve parameters. This proof-of-concept work is promising for future large slitless spectroscopic surveys, such as Euclid and WFIRST.
Highlights
Spectroscopy surveys play a fundamental role in the understanding of galaxy formation and evolution with cosmic time and in cosmology
The one-tailed p-value is computed from the best-fit χ2 without and with kinematics to assess the significance of the fit improvement with the addition of two kinematic parameters
We explored the possibility of probing single objects with slitless spectroscopy, by measuring integrated spectral features, and spatially-resolved quantities such as internal kinematics
Summary
Spectroscopy surveys play a fundamental role in the understanding of galaxy formation and evolution with cosmic time and in cosmology. The VIPERS survey (de la Torre et al 2013) made it possible to map, with unprecedented precision, the large-scale distribution of galaxies by measuring more than 100 000 redshifts at 0.5 < z < 1.2. These fiber-based surveys suffer from drawbacks: galaxy central regions are integrated, so two-dimensional internal structure cannot be properly recovered, and objects need to be selected and targeted a priori
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