J/AJ/157/81 The Arecibo PPS Survey. I. Harvesting ALFALFA (O'Donoghue+, 2019)
The Arecibo Pisces-Perseus Supercluster Survey.
I. Harvesting ALFALFA.
O'Donoghue A.A., Haynes M.P., Koopmann R.A., Jones M.G., Giovanelli R.,
Balonek T.J., Craig D.W., Hallenbeck G.L., Hoffman G.L., Kornreich D.A.,
Leisman L., Miller J.R.
<Astron. J., 157, 81 (2019)>
=2019AJ....157...81O 2019AJ....157...81O (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies, radio ; H I data ; Surveys
Keywords: galaxies: clusters: general - galaxies: distances and redshifts -
large-scale structure of universe - radio lines: galaxies - surveys
Abstract:
We report a multi-objective campaign of targeted 21 cm H I line
observations of sources selected from the Arecibo Legacy Fast Arecibo
L-band Feed Array (ALFALFA) survey and galaxies identified by their
morphological and photometric properties in the Sloan Digital Sky Survey.
The aims of this program have been (1) to confirm the reality of some
ALFALFA sources whose enigmatic nature suggest additional multiwavelength
observations; (2) to probe the low signal-to-noise ratio (S/N) regime,
below the ALFALFA reliability limit; and (3) to explore the feasibility
of using optical morphology, color, and surface brightness to identify
gas-rich objects in the region of the Pisces-Perseus Supercluster (PPS)
whose H I fluxes are below the ALFALFA sensitivity limit at that distance.
As expected, the reliability of ALFALFA detections depends strongly on
the S/N of the H I line signal and its coincidence with a probable stellar
counterpart identified by its optical properties, suggestive of ongoing
star formation. The identification of low-mass, star-forming populations
enables targeted H I line observations to detect galaxies with H I line
fluxes below the ALFALFA sensitivity limits in fixed local volumes
(D<100 Mpc). The method explored here serves as the basis for extending
the sample of gas-bearing objects as part of the ongoing Arecibo
Pisces-Perseus Supercluster Survey (APPSS).
Description:
All observations were conducted with the single-beam L-band wide (LBW)
receiver system. A 1370-1470 MHz filter was used to limit the impact of
human-generated radio frequency interference (RFI). At zenith, the gain of
LBW is about 10.5 K/Jy and the system temperature is typically 25 K. The
LBW observations used a basic pointed total-power (TP) position-switched
(ON-OFF) mode of varying bandwidth (see below) in the 1340-1430 MHz ALFALFA
frequency range. In TP position switching, a source (the ON scan) is
tracked for some time period (usually three to five minutes), then the
telescope is slewed back to the original altitude and azimuth location,
and tracking of that position (the OFF scan) occurs for the same length of
time. A diode of known thermal resistance is fired at the end of each
ON/OFF source pair to provide calibration. Application of the TP mode
assumes that the OFF scan does not contain a source of H I line emission
at the same frequency as the target galaxy. The OFF observation allows for
bandpass subtraction since the effects of the instrument and the sky should
be identical to the ON observation, but without any source emission. For
the observations reported here, we almost always used a three-minute ON-OFF
switching. This observing scheme was designed to allow detection of H I
masses greater than 107 M☉ for <S/N> ∼5.5, an average velocity width
(at half the peak flux) of <W50> ∼100 km/s, and a smoothing factor of 1/2
(e.g., Giovanelli et al. 2005AJ....130.2598G 2005AJ....130.2598G, Section 4.1).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 31 7 Detection rates by category
table2.dat 97 374 Properties of LBW detections
--------------------------------------------------------------------------------
See also:
VIII/77 : HI spectral properties of galaxies (Springob+, 2005)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
J/AJ/105/1251 : Velocities in Pisces-Perseus supercluster. (Wegner+, 1993)
J/AJ/105/1271 : Pisces-Perseus supercluster. VI (Giovanelli+, 1993)
J/A+A/286/17 : 21cm obs. of galaxies in Psc-Per Supercl. (Seeberger+ 1994)
J/A+A/414/905 : H-band photometry in Pisces-Perseus disk galaxies (Hunt+, 2004)
J/AJ/142/170 : ALFALFA survey: the α.40 HI source catalog
(Haynes+, 2011)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Cat Category
18 A1 --- n_Cat Note on Cat (1)
20- 22 I3 --- Ndet [0/207] Number of detection(s)
24- 25 I2 --- Nndet [0/88] Number of non-detection(s)
27- 31 F5.1 % Rate [0/100] Detection rate
--------------------------------------------------------------------------------
Note (1): Note as follows:
a = High S/N ALFALFA sources with low spectral weight, mismatch in
polarizations, large positional offset of H I centroid, or near the
S/N=6.5 limit;
b = High S/N ALFALFA sources with no optical counterpart (OC);
c = Low-S/N ALFALFA sources with an OC of known and coincident redshift;
d = Priors defined in note c, but deemed untrustworthy due to polarization
mismatch, low weight, or suspected contamination by radio frequency
interference (RFI);
e = Low-S/N ALFALFA candidate sources with an OC of unknown redshift;
f = Low-S/N ALFALFA candidate sources of low velocity (cz<1000 km/s), narrow
width, and lacking an OC; none were confirmed;
g = Targets chosen from SDSS visually or by SQL query.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- AGC [937/749170] Entry number from the Arecibo
General Catalog (AGC) (1)
8- 17 F10.6 deg RAdeg HI centroid degree of Right Ascension (J2000)
19- 27 F9.6 deg DEdeg HI centroid degree of Declination (J2000)
29- 44 A16 --- Cat Source category of target (see Table 1)
46- 52 F7.1 km/s RVel [214.6/12461.7] Heliocentric velocity of HI
profile midpoint
54- 57 F4.1 km/s e_RVel [0/46.7] Uncertainty in RVel
59- 64 F6.1 km/s W50 [18.9/1012.1] Observed velocity width at 50%
peak on either side
66- 70 F5.1 km/s e_W50 [0.2/209.8] Uncertainty in W50
72- 76 F5.2 J.km/s FHI [0.09/11.24] HI line flux density
78- 82 F5.3 J.km/s e_FHI [0.01/0.131] Uncertainty in FHI
84- 89 F6.2 Mpc Dist [4.11/173.3] Adopted distance from the ALFALFA
flow model (see Haynes et al. 2011,
J/AJ/142/170)
91- 97 F7.4 [Msun] logMHI [5.84/10.27] Log HI mass
--------------------------------------------------------------------------------
Note (1): The ID number from the AGC, the informal private redshift database
of M. P. Haynes and R. Giovanelli.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 20-May-2019