FIELD: An automated emission-line detection software for Subaru/FMOS near-infrared spectroscopy

Abstract

We describe the development of automated emission line detection software for the Fiber Multi-Object Spectrograph (FMOS), which is a near-infrared spectrograph fed by $400$ fibers from the $0.2$ deg${}^2$ prime focus field of view of the Subaru Telescope. The software, FIELD (FMOS software for Image-based Emission Line Detection), is developed and tested mainly for the FastSound survey, which is targeting H$\alpha$ emitting galaxies at $z\sim 1.3$ to measure the redshift space distortion as a test of general relativity beyond $z\sim 1$. The basic algorithm is to calculate the line signal-to-noise ratio ($S/N$) along the wavelength direction, given by a 2-D convolution of the spectral image and a detection kernel representing a typical emission line profile. A unique feature of FMOS is its use of OH airglow suppression masks, requiring the use of flat-field images to suppress noise around the mask regions. Bad pixels on the detectors and pixels affected by cosmic-rays are efficiently removed by using the information obtained from the FMOS analysis pipeline. We limit the range of acceptable line-shape parameters for the detected candidates to further improve the reliability of line detection. The final performance of line detection is tested using a subset of the FastSound data; the false detection rate of spurious objects is examined by using inverted frames obtained by exchanging object and sky frames. The false detection rate is $<1$\% at $S/N>5$, allowing an efficient and objective emission line search for FMOS data at the line flux level of $\gtrsim 1.0\times 10^{-16}$[erg/cm${}^2$/s].

arXiv comment8 pages, 1 table, 5 figures, accepted to PASJ

References in corpus (10)

• The 2dF Galaxy Redshift Survey: correlation functions, peculiar velocities and the matter density of the Universe
• A test of the nature of cosmic acceleration using galaxy redshift distortions
• The 6dF Galaxy Survey: z \approx 0 measurement of the growth rate and sigma_8
• The WiggleZ Dark Energy Survey: the growth rate of cosmic structure since redshift z=0.9
• The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: measurements of the growth of structure and expansion rate at z=0.57 from anisotropic clustering
• Interpreting large-scale redshift-space distortion measurements
• The VIMOS Public Extragalactic Redshift Survey (VIPERS). Galaxy clustering and redshift-space distortions at z=0.8 in the first data release
• OHS: OH-airglow Suppressor for the Subaru Telescope
• FIBRE-pac: FMOS image-based reduction package
• A Study of Selection Methods for H alpha Emitting Galaxies at z~1.3 for the Subaru/FMOS Galaxy Redshift Survey for Cosmology (FastSound)

Cited by in corpus (5)

• The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at $z\sim 1.4$
• The Subaru FMOS Galaxy Redshift Survey (FastSound). III. The mass-metallicity relation and the fundamental metallicity relation at $z\sim 1.4$
• The Subaru FMOS galaxy redshift survey (FastSound). V. Intrinsic alignments of emission line galaxies at $z\sim 1.4$
• The Subaru FMOS Galaxy Redshift Survey (FastSound). II. The Emission Line Catalog and Properties of Emission Line Galaxies
• The mass--metallicity relation AKARI-FMOS infrared galaxies at $z\sim 0.88$ in the AKARI North Ecliptic Pole Deep Survey Field