Fluctuation of the background sky in the Hubble Extremely Deep Field (XDF) and its origin

Abstract

We performed a fluctuation analysis of the Hubble Extremely Deep Field (XDF) at four optical wavelength bands and found large fluctuations that are significantly brighter than those expected for ordinary galaxies. Good cross-correlations with flat spectra are found down to 0.2 arcsec, indicating the existence of a spatial structure even at the 0.2 arcsec scale. The detected auto and cross-correlations provide a lower limit of 24 nW m${}^{-2}$ sr${}^{-1}$ for the absolute sky brightness at 700-900 nm, which is consistent with previous observations. We searched for candidate objects to explain the detected large fluctuation using the catalog of the Hubble Ultra Deep Field (UDF), and found that the surface number density of faint compact objects (FCOs) rapidly increases toward the faint end. Radial profiles of FCOs are indistinguishable from the PSF, and the effective radius based on de Vaucouleur's law is estimated to be smaller than 0.02 arcsec. The SEDs of FCOs follow a power law at optical wavelengths, but show greater emission and structure at $\lambda$ > 1 $\mu$m. Assuming that the FCOs are the cause of the excess brightness and fluctuations, the faint magnitude limit is 34.9 mag for the F775W band, and the surface number density reaches $2.6\times 10^3$ (arcsec)${}^{-2}$. Recent gamma-ray observations require that the redshift of FCOs must be less than 0.1, if FCOs are the origin of the excess optical and infrared background. Assuming that FCOs consist of missing baryons, the mass and luminosity of a single FCO range from $10^2$ to 1$0^3$ solar units, and mass-to-luminosity ratio is significantly lower than 1.0 solar unit. The maximum effective radius of an FCO is 4.7 pc. These results and the good correlation between near-infrared and X-ray background indicate that FCOs could be powered by the gravitational energy associated with black holes.

37 pages, 21 figures, accepted to PASJ

References in corpus (22)

• The Hubble Ultra Deep Field
• Galaxies in the Hubble Ultra Deep Field: I. Detection, Multiband Photometry, Photometric Redshifts, and Morphology
• The FourStar Galaxy Evolution Survey (ZFOURGE): ultraviolet to far-infrared catalogs, medium-bandwidth photometric redshifts with improved accuracy, stellar masses, and confirmation of quiescent galaxies to z~3.5
• UVUDF: Ultraviolet Through Near-infrared Catalog and Photometric Redshifts of Galaxies in the Hubble Ultra Deep Field
• The MUSE Hubble Ultra Deep Field Survey: II. Spectroscopic redshifts and comparisons to color selections of high-redshift galaxies
• A $\gamma$-ray determination of the Universe's star-formation history
• On the Origin of Near-Infrared Extragalactic Background Light Anisotropy
• The Nature of Extreme Emission Line Galaxies at z=1-2: Kinematics and Metallicities from Near-Infrared Spectroscopy
• New Spectral Evidence of an Unaccounted Component of the Near-infrared Extragalactic Background Light from the CIBER
• A Hard Ionizing Spectrum in z=3-4 Ly-alpha Emitters with Intense [OIII] Emission: Analogs of Galaxies in the Reionization Era?
• Constraints on the Cosmic Near Infrared Background Excess from NICMOS Deep Field Observations
• Measurement of the Cosmic Optical Background using the Long Range Reconnaissance Imager on New Horizons
• DIRBE Minus 2MASS: Confirming the CIRB in 40 New Regions at 2.2 and 3.5 Microns
• Extragalactic background Light: a measurement at 400 nm using dark cloud shadow II. Spectroscopic separation of dark cloud's light, and results
• Ultraviolet to optical diffuse sky emission as seen by the Hubble Space Telescope Faint Object Spectrograph
• Probing large scale coherence between Spitzer IR and Chandra X-ray source-subtracted cosmic backgrounds
• AKARI Observation of the Sub-degree Scale Fluctuation of the Near-infrared Background
• Zodiacal Light Beyond Earth Orbit Observed with Pioneer 10
• Cross-correlation between X-ray and optical/near-infrared background intensity fluctuations
• Large angular scale fluctuations of near infrared extragalactic background light based on the IRTS observations
• The Contribution of Faint Galaxy Wings to Source-subtracted Near-infrared Background Fluctuations
• M32 Analogs? A Population of Massive Ultra Compact Dwarf and Compact Elliptical Galaxies in intermediate redshift CLASH Clusters

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