J/MNRAS/444/2456 Spectral galaxy pairs from SDSS DR9 (Yang+, 2014) ================================================================================ A search for spectral galaxy pairs of overlapping galaxies based on fuzzy recognition. Yang H., Luo A., Chen X., Zhang J., Hou W., Cai J., Wei P., Ren J., Liu X., Zhao Y. =2014MNRAS.444.2456Y ================================================================================ ADC_Keywords: Galaxy catalogs ; Redshifts ; Morphology Keywords: methods: data analysis - dust, extinction - galaxies: evolution - galaxies: ISM Abstract: Spectral galaxy pairs (hereafter as SGPs) are composite galaxy spectra that contain two independent redshift systems. These spectra are useful for studying the dust properties of the foreground galaxies. In this article, a total of 165 spectra of SGPs are mined from the Sloan Digital Sky Survey (SDSS) Data Release 9 (DR9) using the concept of 'membership degree' from fuzzy set theory, especially defined to be suitable for fuzzy identification of emission lines. The spectra and images of this sample are classified according to their membership degree and image features, respectively. Many of the second redshift systems are too small or too dim to select from SDSS images alone, making the sample a potentially unique source of information on dust effects in low-luminosity or low surface brightness galaxies, which are underrepresented in morphological pair samples. The dust extinction of those objects with high membership degree is also estimated by Balmer decrement. Additionally, analyses for a series of spectroscopic observations of one SGP from 165 systems indicate that a newly star-forming region of our Milky Way might exist. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file tablea1.dat 91 165 SGP (Spectral Galaxy Paris) sample selected from SDSS DR9 -------------------------------------------------------------------------------- See also: http://www.sdss.org : SDSS Home Page Byte-by-byte Description of file: tablea1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- Seq [1/165] SGP sequential number 4 A1 --- n_Seq [*] 2 redshift values exist in SDSS (1) 6- 9 A4 --- --- [SDSS] 11- 29 A19 --- SDSS SDSS source name (2) 31- 39 F9.5 deg RAdeg ?=- Right ascension (J2000) 41- 49 F9.5 deg DEdeg ?=- Declination (J2000) 51- 56 F6.4 --- z1 [0/0.22] First redshift (3) 58- 64 F7.5 --- e_z1 [0/0.02] rms uncertainty on z1 (3) 66- 71 F6.4 --- z2 [0/0.38] Second redshift (3) 73- 79 F7.5 --- e_z2 [0/0.10] rms uncertainty on z2 (3) 81 A1 --- Grade [ABCD] Grade level of spectrum, A=best (4) 83- 85 A3 --- Env Environment of the SGP (5) 87- 91 A5 --- Refs Relevant references for objects that appear in the literature (6) -------------------------------------------------------------------------------- Note (1): * indicates sources for which there are at least two values in the XCRedshift results close to the values identified by our method. Note (2): SDSS JHHMMSS.ss+DDMMSS.s, except source 130, Plate-MJD-Fiber. Note (3): The two redshifts (errors) are determined from the core wavelength of the best-fitting emission lines. Note (4): Level is classified according to different membership degree thresholds. Note (5): Environment is classified from visual inspection as follows: FPV = Face-on-Pair Visible. Two galaxies can be separated visually in the image and they are both face-on to us. FPI = Face-on-Pair Invisible FGV = Face-on-Group Visible. These are multiple galaxy systems. Most of the galaxies in these systems are face-on to us and several objects can be separated in the images. FGI = Face-on-Group Invisible EPV = Edge-on-Pair Visible. The main difference with FPV is that these galaxies are edge-on to us. EPI = Edge-on-Pair Invisible. EGI = Edge-on-Group Invisible. Note (6): Notes as follows: 1 = Eke et al. (2004MNRAS.348..866E, Cat. J/MNRAS/348/866) 2 = Merchan & Zandivarez (2005) 3 = Berlind et al. (2006ApJS..167....1B, Cat. J/ApJS/167/1) 4 = Allam et al. (2004AJ....127.1883A, Cat. J/AJ/127/1883) 5 = Keel et al. (2013PASP..125....2K, Cat. J/PASP/125/2) 6 = Holwerda, Keel & Bolton (2007AJ....134.2385H, Cat. J/AJ/134/2385) 7 = Liu et al. (2011ApJ...737..101L, Cat. J/ApJ/737/101) 8 = Ge et al. (2012ApJS..201...31G, Cat. J/ApJS/201/31) 9 = McConnachie et al. (2009MNRAS.395..255M, Cat. J/MNRAS/395/255) 10 = Kopparapu et al. (2008ApJ...675.1459K, Cat. J/ApJ/675/1459) 11 = Marino et al. (2013MNRAS.428..476M) -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Patricia Vannier [CDS] 28-Apr-2015