J/AJ/160/242 The Hα dots survey. II. 119 new dots (Salzer+, 2020)
The Hα dots survey.
II. A second list of faint emission-line objects.
Salzer J.J., Feddersen J.R., Derloshon K., Gronwall C., Van Sistine A.,
Sugden A., Janowiecki S., Hirschauer A.S., Kellar J.A.
<Astron. J., 160, 242 (2020)>
=2020AJ....160..242S 2020AJ....160..242S
ADC_Keywords: Star Forming Region; H II regions; Galaxies, Seyfert; QSOs;
Spectra, optical; Redshifts
Keywords: Galaxy abundances ; Dwarf galaxies ; Blue compact dwarf galaxies ;
Seyfert galaxies ; Quasars ; Starburst galaxies ; Star formation ;
Emission line galaxies
Abstract:
We present the second catalog of serendipitously discovered compact
extragalactic emission-line sources-Hα Dots. These objects have
been discovered in searches of moderately deep narrow-band images
acquired for the ALFALFA Hα project. In addition to cataloging
119 new Hα Dots, we also present follow-up spectral data for the
full sample. These spectra allow us to confirm the nature of these
objects as true extragalactic emission-line objects, to classify them
in terms of activity type (star-forming or AGN), and to identify the
emission line via which they were discovered. We tabulate photometric
and spectroscopic data for the all objects, and we present an overview
of the properties of the full Hα Dot sample. The Hα Dots
represent a broad range of star-forming and active galaxies detected
via several different emission lines over a wide range of redshifts.
The sample includes Hα-detected blue compact dwarf galaxies at
low redshift, [OIII]-detected Seyfert 2 and Green Pea-like galaxies at
intermediate redshifts, and QSOs detected via one of several UV
emission lines, including Lyα. Despite the heterogeneous
appearance of the resulting catalog of objects, we show that our
selection method leads to well-defined samples of specific classes of
emission-line objects with properties that allow for statistical
studies of each class.
Description:
The Hα Dots survey is carried out using narrow-band images
obtained for the ALFALFA Hα (AHA) project;
Van Sistine+, 2016ApJ...824...25V 2016ApJ...824...25V (Paper I).
The AHA data consist of images obtained through both a continuum
R-band filter and one of a set of narrow-band (∼60-70Å wide)
Hα filters. Two telescopes were used for the AHA observations:
the University of Wisconsin-Madison, Indiana University (WIYN) 0.9m
and Kitt Peak National Observatory (KPNO) 2.1m telescopes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 79 119 Second list of Hα dots
table2.dat 67 119 Measured spectral properties
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See also:
VIII/1 : The 3C and 3CR Catalogues (Edge+ 1959-1962)
J/MNRAS/204/151 : Bright radio sources at 178 MHz (3CRR) (Laing+ 1983)
J/ApJS/95/387 : Universidad Complutense de Madrid list 1 (Zamorano+ 1994)
J/ApJS/105/343 : Universidad Complutense de Madrid list 2 (Zamorano+ 1996)
J/A+AS/135/511 : The Hamburg/SAO Survey for ELGs (Ugryumov+ 1999)
J/A+AS/142/417 : Hamburg/SAO Survey for ELGs. III. (Hopp+, 2000)
J/AJ/121/66 : KISS Hα survey list 1 (Salzer+, 2001)
J/AJ/123/1292 : KISS III. [O III]-selected survey list (Salzer+, 2002)
J/AJ/127/1943 : KISS Hα survey list 2 (Gronwall+, 2004)
J/ApJ/668/853 : Spectro. of UltraStrong Emission Line galaxies (Kakazu+,2007)
J/AJ/139/279 : Outlying HII regions in HI-selected galaxies (Werk+, 2010)
J/AJ/142/170 : ALFALFA survey: α.40 HI source catalog (Haynes+, 2011)
J/AJ/143/145 : Emission-line from ALFALFA Hα survey (Kellar+, 2012)
J/A+A/559/A114 : Updated O3N2 and N2 abundance indicators (Marino+, 2013)
J/ApJ/844/171 : Lyα profile in 43 Green Pea galaxies (Yang+, 2017)
J/ApJ/861/49 : ALFALFA extragalactic HI source catalog (Haynes+, 2018)
J/ApJ/880/7 : Census of the Local Universe survey I CLU-Halpha (Cook+,2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Dot [62/180] Hα dot candidate number (1)
5- 5 A1 --- f_Dot Duplicated detections flag (2)
7- 15 F9.5 deg RAdeg [1.63/352] Right Ascension (J2000) (3)
17- 24 F8.5 deg DEdeg [4.05/28.1] Declination (J2000) (3)
26- 30 F5.2 mag Dmag [-2.75/-0.34] Difference, continuum and narrow
band magnitudes (4)
32- 37 F6.2 --- Ratio [4.5/112] Ratio, magnitude difference Dmag to
magnitude difference error (5)
39- 43 F5.2 mag Rmag [15.41/22.13] measured R-band magnitude from
continuum images
45- 48 F4.2 mag e_Rmag [0.02/0.32] Uncertainty in Rmag
50- 54 F5.3 10-17W/m2 NBFlux [0.05/5.99] Narrowband Line Flux,
10-14erg/s/cm2 (6)
56- 60 F5.3 10-17W/m2 e_NBFlux [0.008/0.09] Uncertainty in NBFlux,
10-14erg/s/cm2 (6)
62- 67 F6.2 mag RMAG [-28.5/-10.6]? R-band absolute magnitude
69- 73 F5.2 10-7W logHa [38.5/43.16]? log, Hα luminosity, erg/s
75- 79 F5.2 [Msun/yr] logSFR [-2.6/1.75]? log, H{alphas}-based
star-formation rate
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Note (1): Following the convention established in
Kellar+, 2012, 2012AJ....143..145K 2012AJ....143..145K, the Hα Dot candidates are
numbered sequentially in right ascension (RA) order for all objects
found from the search of the fields from a given AHA observing run.
Note (2): Duplicate detections 'a' (9 occurrences) represent independent
detections of the same object found in two fields observed on
different observing runs:
Hα Dot 63 = Hα Dot 108;
Hα Dot 73 = Hα Dot 30;
Hα Dot 78 = Hα Dot 47;
Hα Dot 86 = Hα Dot 51;
Hα Dot 109 = Hα Dot 148;
Hα Dot 129 = Hα Dot 49;
Hα Dot 160 = Hα Dot 43.
Note (3): The coordinates listed are typically those measured by the Sloan
Digital Sky Survey: York+, 2000AJ....120.1579Y 2000AJ....120.1579Y;
Abolfathi+, 2018ApJS..235...42A 2018ApJS..235...42A.
Note (4): Dmag=mNB-mR (see Section 2 and Equation (1) for more details).
Note (5): Ratio=Dmag/e_Dmag (see Section 3 and Equation (2) for more details)
Note (6): Narrow-band fluxes are calibrated using spectrophotometric
standard stars obtained nightly as part of the AHA survey. We note that
these emission-line fluxes are not Hα fluxes in all cases. As
discussed in Sections 4 and 5, for many of the objects in our survey the
emission line detected is a line other than Hα.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Dot [62/180] Hα dot candidate number
5- 10 A6 --- Type Emission-line galaxy type (1)
12- 18 F7.4 --- z [-0.0001/4.5] observed redshift
20- 24 F5.2 --- cHb [-0.17/1.61]? Decimal reddening coefficient (2)
26- 31 F6.1 0.1nm Eq(Ha) [12.6/2041]? Equivalent width of the Hα line
33- 38 F6.1 0.1nm Eq(O3) [3.9/1780]? Equivalent width of the [OIII] line
40- 44 F5.2 [-] logN2/Ha [-2.26/0.05]? log, [NII(6583Å)]/Hα
emission line flux ratio (3)
46- 50 F5.2 [-] logO3/Hb [-0.43/1.41]? log, [OIII 5007Å)]/Hβ
emission line flux ratio (3)
52- 56 F5.2 [-] logO2/Hb [-0.85/1.12]? log, [OII(3727Å)]/Hβ
emission line flux ratio (3)
58- 62 F5.2 [-] logS2/Ha [-1.35/-0.24]? log,
[SII(6717Å, 6731Å)]/Hα emission line
flux ratio (3)
64- 67 F4.2 [Sun] [O/H] [7.4/8.97]? Metallicity, log(O/H)+12
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Note (1): Emission-line galaxy type as follows:
SFG = star-forming galaxy (77 occurrences)
HII = outlying/isolated HII region (13 occurrences)
Sy1 = Seyfert 1 galaxy (2 occurrences)
Sy2 = Seyfert 2 galaxy (13 occurrences)
QSO = quasi-stellar object (5 occurrences)
NotELG = a false detection whose spectrum displays no emission lines (9
occurrences)
Note (2): cHb is nearly always derived from the observed Hα/Hβ
ratio. In a few cases of higher-redshift systems where Hα is not
observed we use the Hγ/Hβ ratio instead.
Note (3): Logarithms of the specified ratios of emission-line fluxes. The
line ratios have all been corrected for reddening using the value of cHb
given in column 4. Because the wavelength coverage of the spectra is
fixed, but the redshifts of the objects vary over a huge range, many
of the line ratios indicated are not available for a given object.
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History:
From electronic version of the journal
References:
Van Sistine et al. Paper I : 2016ApJ...824...25V 2016ApJ...824...25V
(End) Prepared by [AAS], Coralie Fix [CDS], 29-Jan-2021