Spectrophotometric Redshifts In The Faint Infrared Grism Survey: Finding Overdensities Of Faint Galaxies

Abstract

We improve the accuracy of photometric redshifts by including low-resolution spectral data from the G102 grism on the Hubble Space Telescope, which assists in redshift determination by further constraining the shape of the broadband Spectral Energy Disribution (SED) and identifying spectral features. The photometry used in the redshift fits includes near-IR photometry from FIGS+CANDELS, as well as optical data from ground-based surveys and HST ACS, and mid-IR data from Spitzer. We calculated the redshifts through the comparison of measured photometry with template galaxy models, using the EAZY photometric redshift code. For objects with F105W $<26.5$ AB mag with a redshift range of $0<z<6$, we find a typical error of $\Delta z=0.03\ast (1+z)$ for the purely photometric redshifts; with the addition of FIGS spectra, these become $\Delta z=0.02\ast (1+z)$, an improvement of 50\%. Addition of grism data also reduces the outlier rate from 8\% to 7\% across all fields. With the more-accurate spectrophotometric redshifts (SPZs), we searched the FIGS fields for galaxy overdensities. We identified 24 overdensities across the 4 fields. The strongest overdensity, matching a spectroscopically identified cluster at $z=0.85$, has 28 potential member galaxies, of which 8 have previous spectroscopic confirmation, and features a corresponding X-ray signal. Another corresponding to a cluster at $z=1.84$ has 22 members, 18 of which are spectroscopically confirmed. Additionally, we find 4 overdensities that are detected at an equal or higher significance in at least one metric to the two confirmed clusters.

arXiv comment17 pages, 13 figures. To appear in ApJ

References in corpus (36)

• Cosmic Star Formation History
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey - The Hubble Space Telescope Observations, Imaging Data Products and Mosaics
• The James Webb Space Telescope
• EAZY: A Fast, Public Photometric Redshift Code
• Accurate photometric redshifts for the CFHT Legacy Survey calibrated using the VIMOS VLT Deep Survey
• The Great Observatories Origins Deep Survey: Initial Results From Optical and Near-Infrared Imaging
• K-corrections and filter transformations in the ultraviolet, optical, and near infrared
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Bayesian photometric redshift estimation
• 3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses
• The 3D-HST Survey: Hubble Space Telescope WFC3/G141 grism spectra, redshifts, and emission line measurements for $\sim 100,000$ galaxies
• The Evolution of the Galaxy Rest-Frame Ultraviolet Luminosity Function Over the First Two Billion Years
• 3D-HST: A wide-field grism spectroscopic survey with the Hubble Space Telescope
• Lyman Break Galaxies at Redshift z~3: Survey Description and Full Data Set
• The Chandra Deep Field-South Survey: 7 Ms Source Catalogs
• Spectroscopy of Lyman Break Galaxies in the Hubble Deep Field
• A Critical Assessment of Photometric Redshift Methods: A CANDELS Investigation
• A Deep, Wide Field, Optical, and Near Infrared Catalog of a Large Area around the Hubble Deep Field North
• GaBoDS: The Garching-Bonn Deep Survey; IV. Methods for the Image reduction of multi-chip Cameras
• A Spitzer-Selected Galaxy Cluster at z=1.62
• The Great Observatories Origins Deep Survey
• Deep U band and R imaging of GOODS-South: Observations,data reduction and first results
• First Results from Z-FOURGE: Discovery of a Candidate Cluster at z = 2.2 in COSMOS
• The Slitless Spectroscopy Data Extraction Software aXe
• The Great Observatories Origins Deep Survey - VLT/ISAAC Near-Infrared Imaging of the GOODS-South Field
• GRAPES, Grism Spectroscopy of the Hubble Ultra Deep Field: Description and Data Reduction
• Serendipitously Detected Galaxies in the Hubble Deep Field
• GaBoDS: The Garching-Bonn Deep Survey V. Data release of the ESO Deep-Public-Survey
• MOIRCS Deep Survey. IX. Deep Near-Infrared Imaging Data and Source Catalog
• FIGS -- Faint Infrared Grism Survey: Description and Data Reduction
• Star-forming blue ETGs in two newly discovered galaxy overdensities in the HUDF at z=1.84 and 1.9: unveiling the progenitors of passive ETGs in cluster cores
• Ultra-deep catalog of X-ray groups in the Extended Chandra Deep Field South
• The Galaxy Luminosity Function at z~1 in the HUDF: Probing the Dwarf Population
• Cosmic shear from STIS Pure Parallels: I Data
• Emission line selected galaxies at $z=0.6-2$ in GOODS South: Stellar masses, SFRs, and large scale structure

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• Spectrophotometric redshifts for $\mathrm{z}\sim 1$ galaxies and predictions for number densities with WFIRST and Euclid
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