J/ApJ/950/189ivo://CDS.VizieR/J/ApJ/950/189CDSDraper C.D.Moody J.W.McNeil S.R.Joner M.D.Steele R.Steele J.2025-10-01T06:29:29Z2025-09-22T13:18:40ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frdwarf-galaxiesvisible-astronomyh-alpha-photometrysloan-photometryintergalactic-mediumline-intensitiesredshiftedThe population density of dwarf galaxies in low-density voids is likely determined by the dark matter halo mass function and how galaxy formation proceeds in smaller halos. This depends on the nature of dark matter itself, making the dwarf galaxy population a tracer of its properties. While dwarfs have been found in smaller, closer voids, they have proven difficult to find in larger, more distant voids through magnitude-limited spectroscopic surveys. This is because these surveys detect an overwhelmingly large number of objects behind the voids that must be verified spectroscopically, making void surveys prohibitively inefficient and expensive in terms of large-telescope time. Narrowband imaging for emission lines such as H{alpha} reduces the number of background objects, although the overall number remains large. If imaging is done through a filter set with overlapping transmission wings, then object redshift can be estimated from photometry alone. The precision possible is an order of magnitude greater than single-band photometry, with the caveat that the captured line must be identified through other means. Broadband photometry can be used to reject enough objects with emission of an unwanted type to make obtaining spectra of the remaining objects feasible. In this study, we present an H{alpha} survey for dwarf galaxies with M_r_' fainter than -14mag through the center 4.3 square degrees of the void FN8. Using Sloan g', r', i' photometry, we exclude enough [OII] and [OIII] emitters that follow-up spectra of only a few dozen objects are required to statistically estimate the void population density.2023ApJ...950..189Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/950/189CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/284 : The USNO-B1.0 Catalog (Monet+ 2003)II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)J/AJ/95/1629 : [O III] emission in 2 field-galaxy surveys (Moody+ 1988)J/PASP/111/438 : Updated Zwicky catalog (UZC) (Falco+, 1999)J/AJ/118/2561 : Galaxies within prominent nearby voids (Grogin+, 1999)J/MNRAS/335/712 : R magnitude of cluster of galaxies (Trentham+, 2002)J/AJ/130/2571 : KISS H{alpha}-selected survey list 3 (Jangren+, 2005)J/ApJS/176/301 : Subaru/XMM-Newton deep survey IV. (SXDS) (Ouchi+, 2008)J/AJ/144/16 : Opt. and HI properties of galaxies in voids (Kreckel+, 2012)J/MNRAS/464/666 : Void Galaxy Survey, photometry and structure (Beygu+, 2017)J/ApJ/837/42 : N/O ratio of dwarf galaxies from SDSS (Douglass+, 2017)J/MNRAS/471/629 : Bootes-HiZELS. Em.-line gal. at z=0.4-4.7 (Matthee+, 2017)J/ApJ/864/144 : N/O and Ne/O ratios of SDSS dwarf galaxies (Douglass+, 2018)J/MNRAS/476/4725 : SC4K catalogue of candidate LAEs (Sobral+, 2018)J/AJ/157/99 : Phot. redshifts of emission-line galaxies (Lesser+, 2019)J/MNRAS/482/4329 : Void galaxies in the nearby Universe (Pustilnik+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/950/189https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/950/189http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/950/189https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/950/189https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/950/189http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/950/189GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/950/189/emcand (Emission-line candidates in the 1sigma region (Table 6) and in the 2sigma region (Table 7))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/950/189/emcand?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/950/189/emcand?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/950/189/emcand?GETtext/xml+votable180.050000true197.2159708372.447473330.0055555555555555565/3001 6/11994-11995 12003 12012 12016-120182.85864675833786e-19 3.5010283109654867e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/950/189?format=asciiOpticaldefaultJ/ApJ/950/189/emcandEmission-line candidates in the 1sigma region (Table 6) and in the 2sigma region (Table 7)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRegobjects that fall within the 1sigma or the 2sigma regionsmeta.codecharFieldField identifiermeta.id;obs.fieldcharID[3467/21046] Candidate internal identifiermeta.id;meta.mainintRAJ2000[12/13] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[71/73] Degree of Declination (J2000)pos.eq.dec;meta.mainrmag[20.2/23.8] SDSS r' band apparent AB magnitudemagphot.mag;em.opt.RfloatEW[40/1690] Equivalent width; Angstroms0.1nmspect.line.eqWidthintDepth[0.28/0.81] Depth in void; estimated cz assuming the emission line is H{alpha}phys.absorption.opticalDepthfloat