On the Origin of the Strong Optical Variability of Emission-line Galaxies

Abstract

Emission-line galaxies (ELGs) are crucial in understanding the formation and evolution of galaxies, while little is known about their variability. Here we report the study on the optical variability of a sample of ELGs selected in the COSMOS field, which has narrow-band observations in two epochs separated by $\gtrsim$ 12 years. This sample was observed with Suprime-Cam (SC) and Hyper Suprime-Cam (HSC) on the $Subaru$ telescope in NB816 and $i^{\prime }/i$ bands, respectively. After carefully removing the wing effect of a narrow-band filter, we check the optical variability in a sample of 181 spectroscopically confirmed ELGs. We find that 0 (0/68) Ha emitters, 11.9% (5/42) [OIII] emitters, and 0 (0/71) [OII] emitters show significant variability ($|\Delta m_{NB}|\ge 3{\sigma }_{\Delta m_{NB,AGN}}=0.20mag$) in the two-epoch narrow-band observations. We investigate the presence of active galactic nucleus (AGN) in this variable ELG (var-ELG) sample with three methods, including X-ray luminosity, mid-infrared activity, and radio-excess. We find zero bright AGN in this var-ELG sample, but cannot rule out the contribution from faint AGN. We find that SNe could also dominate the variability of the var-ELG sample. The merger morphology shown in the HST/F814W images of all the var-ELG sample is in agreement with the enhancement of star formation, i.e., the SNe activity.

arXiv comment20 pages, 10 figures, accepted for publication in The Astrophysical Journal

References in corpus (79)

• Astropy: A Community Python Package for Astronomy
• The Sloan Digital Sky Survey: Technical Summary
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Star Formation in Galaxies Along the Hubble Sequence
• Cosmic Star Formation History
• The Host Galaxies and Classification of Active Galactic Nuclei
• The Cosmic Evolution Survey (COSMOS) -- Overview
• The Sixteenth Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
• The COSMOS2015 Catalog: Exploring the 1<z<6 Universe with half a million galaxies
• The Hyper Suprime-Cam SSP Survey: Overview and Survey Design
• The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures
• 3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses
• Mid-Infrared Selection of Active Galaxies
• The First Release COSMOS Optical and Near-IR Data and Catalog
• The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts
• The 3D-HST Survey: Hubble Space Telescope WFC3/G141 grism spectra, redshifts, and emission line measurements for $\sim 100,000$ galaxies
• Subaru Prime Focus Camera -- Suprime-Cam --
• The Spitzer Legacy Survey of the HST-ACS 2 sq. deg. COSMOS Field: survey strategy and first analysis
• Galaxy And Mass Assembly (GAMA): end of survey report and data release 2
• The Chandra Deep Field South: Optical Spectroscopy I
• The 6dF Galaxy Survey: Samples, Observational Techniques and the First Data Release
• Nearby Supernova Rates from the Lick Observatory Supernova Search. III. The Rate-Size Relation, and the Rates as a Function of Galaxy Hubble Type and Colour
• Understanding Galaxy Evolution through Emission Lines
• The WiggleZ Dark Energy Survey: Survey Design and First Data Release
• Science Objectives and Early Results of the DEEP2 Redshift Survey
• The Chandra COSMOS Legacy survey: overview and point source catalog
• The Sloan Digital Sky Survey Quasar Catalog: Fourteenth Data Release
• Tidal Disruption Events
• The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN
• The VIMOS VLT Deep Survey final data release: a spectroscopic sample of 35016 galaxies and AGN out to z~6.7 selected with 17.5<=i_{AB}<=24.7
• The Cosmic Evolution Survey (COSMOS): Subaru Observations of the HST COSMOS Field
• Third Data Release of the Hyper Suprime-Cam Subaru Strategic Program
• The XMM-Newton wide-field survey in the COSMOS field: I. Survey description
• The PRIsm MUlti-Object Survey (PRIMUS) I: Survey Overview and Characteristics
• Caltech Core-Collapse Project (CCCP) observations of type IIn supernovae: typical properties and implications for their progenitor stars
• The VIMOS Public Extragalactic Survey (VIPERS): First Data Release of 57 204 spectroscopic measurements
• Galaxy pairs in the Sloan Digital Sky Survey - VI. The orbital extent of enhanced star formation in interacting galaxies
• The VLA-COSMOS Survey. IV. Deep Data and Joint Catalog
• Luminous Thermal Flares from Quiescent Supermassive Black Holes
• The DEIMOS 10k spectroscopic survey catalog of the COSMOS field
• Type Ia Supernovae and the Hubble Constant
• Carnegie Supernova Project: Observations of Type IIn supernovae
• Observations of the Lyman-$\alpha$ Universe
• The sizes, masses and specific star-formation rates of massive galaxies at 1.3<z<1.5: strong evidence in favour of evolution via minor mergers
• HiZELS: a high redshift survey of H-alpha emitters. I: the cosmic star-formation rate and clustering at z=2.23
• The DEEP3 Galaxy Redshift Survey: The Impact of Environment on the Size Evolution of Massive Early-type Galaxies at Intermediate Redshift
• The WIRCam Deep Survey I: Counts, colours and mass-functions derived from near-infrared imaging in the CFHTLS deep fields
• The PRIsm MUlti-object Survey (PRIMUS). II. Data Reduction and Redshift Fitting
• The VLA-COSMOS 3~GHz Large Project: AGN and host-galaxy properties out to z$\lesssim$6
• Interaction-induced star formation in a complete sample of 10^5 nearby star-forming galaxies
• The XMM-Newton wide-field survey in the COSMOS field II: X-ray data and the logN-logS
• The Cluster and Field Galaxy AGN Fraction at z = 1 to 1.5: Evidence for a Reversal of the Local Anticorrelation Between Environment and AGN Fraction
• Effects of Pre-ionisation in Radiative Shocks I: Self-Consistent Models
• The FMOS-COSMOS survey of star-forming galaxies at z~1.6 III. Survey design, performance, and sample characteristics
• High velocity outflows from young star-forming galaxies in the UKIDSS Ultra-Deep Survey
• AGNs and galaxy interactions
• The VANDELS ESO public spectroscopic survey: observations and first data release
• The Complete Calibration of the Color-Redshift Relation (C3R2) Survey: Survey Overview and Data Release 1
• The Complete Calibration of the Color-Redshift Relation (C3R2) Survey: Analysis and Data Release 2
• Optical variability of AGN in the PTF/iPTF survey
• The Evolution of Active Galactic Nuclei in Clusters of Galaxies to Redshift 1.3
• The DEEP3 Galaxy Redshift Survey: Keck/DEIMOS Spectroscopy in the GOODS-N Field
• The Large Early Galaxy Astrophysics Census (LEGA-C) Data Release II: dynamical and stellar population properties of z ~< 1 galaxies in the COSMOS field
• LoCuSS: A Dynamical Analysis of X-ray AGN in Local Clusters
• Excess AGN Activity in the z=2.30 Protocluster in HS 1700+64
• The Chandra Deep Protocluster Survey: Point-Source Catalogs for a 400 ks Observation of the z = 3.09 Protocluster in SSA22
• Long Term Spectral Evolution of Tidal Disruption Candidates Selected by Strong Coronal Lines
• EUCLIA - Exploring the UV/optical continuum lag in active galactic nuclei. I. a model without light echoing
• The long-lived Type IIn SN 2015da: Infrared echoes and strong interaction within an extended massive shell
• Variability-based AGN selection using image subtraction in the SDSS and LSST era
• A 16 deg${}^2$ survey of emission-line galaxies at z<1.5 in HSC-SSP PDR1
• Recalibration of [O II] $\lambda 3727$ as a Star Formation Rate Estimator for Active and Inactive Galaxies
• Optically variable active galactic nuclei in the 3 yr VST survey of the COSMOS field
• A Plethora of AGN Among Lyman Alpha Galaxies at Low Redshift
• A large, deep 3 deg${}^2$ survey of H$\alpha$, [OIII], and [OII] emitters from LAGER: constraining luminosity functions
• The host galaxy properties of variability selected AGN in the Pan-STARRS1 Medium-Deep Survey
• SN 2016gsd: An unusually luminous and linear type II supernova with high velocities
• MUSSES2020J: The Earliest Discovery of a Fast Blue Ultraluminous Transient at Redshift 1.063
• Emission Line Galaxies in the SHARDS Frontier Fields I: Candidate Selection and the Discovery of Bursty Hα Emitters