J/ApJS/245/3 HI 21cm and OH 18cm absorption search with the GBT (Grasha+, 2019)
A search for intrinsic HI 21cm and OH 18cm absorption toward compact radio
sources.
Grasha K., Darling J., Bolatto A., Leroy A.K., Stocke J.T.
<Astrophys. J. Suppl. Ser., 245, 3 (2019)>
=2019ApJS..245....3G 2019ApJS..245....3G
ADC_Keywords: Active gal. nuclei; Redshifts; H I data; Radio lines
Keywords: Radio sources ; Quasar absorption line spectroscopy ; Galaxy nuclei ;
Interstellar medium ; Galaxies ; Active galaxies
Abstract:
We present the results of a large search for intrinsic HI 21cm and OH
18cm absorption in 145 compact radio sources in the redshift range
0.02<z<3.8 with the Green Bank Telescope. We redetect HI 21cm
absorption toward six known absorption systems, but detect no new HI
or OH absorption in 102 interference-free sources. Seventy-nine
sources have not previously been observed for HI 21cm absorption. We
recover a mean optical depth limit of τ3σ<0.023 for all
the nondetections in the survey. Our results do not support the high
intrinsic absorption rates found by previous studies in compact radio
sources at low redshift. Our results do, however, support the
hypothesis proposed by Curran+ (2019MNRAS.484.1182C 2019MNRAS.484.1182C) that high
ultraviolet (UV) luminosity active galactic nuclei do not show
intrinsic HI 21cm absorption, confirming a threshold of
LUV=1023W/Hz, above which our intrinsic absorption fraction is
zero (54 sources). The exact nature of the UV luminosity effect on HI
absorption systems remains ambiguous. We additionally find no
statistical correlation between the 1.4GHz radio luminosity or the
source size and the 21cm absorption detection rate. We attribute the
lack of intrinsic absorption in our survey to the UV luminosity effect
caused by an optical selection bias and a decreased column density
sensitivity with increasing redshift due to lower radio continuum flux
densities, high radio frequency interference, and higher telescope
system temperatures at low frequencies.
Description:
Using the Green Bank Telescope (GBT), from 2004 September to 2005
August, 85 Flat-spectrum Radio Sources (FSRSs) were observed for
intrinsic absorption in the HI 21cm line (1420.405752MHz), and 81 in
the four 18cm OH lines at 1612.231, 1665.4018, 1667.35903, and
1720.5300MHz simultaneously (GBT program 04C-018). We additionally
observed 60GHz-peaked Spectrum (GPS), Compact Steep-spectrum (CSS),
and Compact Symmetric Object (CSO) radio sources for intrinsic
absorption from 2005 December to 2006 May (GBT program 06A-044): 59
sources were observed in the HI 21cm line, and 44 sources were
observed in the four OH 18cm lines. One source, PKS 2135-209, was only
observed in the OH lines.
Throughout this paper, we adopt a flat ΛCDM cosmology with
Ωm=0.27, ΩΛ=0.73, and Ho=71km/s/Mpc. All
quantities obtained from the literature are recalculated (if
necessary) for this cosmology.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 100 145 Observations of intrinsic HI and OH lines toward
compact radio sources
table2.dat 135 144 HI 21cm line observations, column densities, and
source sizes
table3.dat 141 120 OH 18cm observations and column density limits
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See also:
VIII/2 : Molonglo Reference Catalog of Radio Sources (Large+ 1981)
VIII/37 : The Third Bologna Survey (B3) (Ficarra+ 1985)
VIII/17 : The North 20cm Survey (White+ 1992)
VIII/42 : Texas Survey of radio sources at 365MHz (Douglas+ 1996)
VIII/34 : Parkes Half-Jansky Flat-Spectrum Sample (Drinkwater+ 1997)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
II/282 : The SDSS Photometric Catalog, Release 6 (Adelman-McCarthy+, 2007)
J/ApJS/95/1 : Atlas of Quasar Energy Distributions (Elvis+ 1994)
J/A+AS/115/11 : Optical identifications of radio sources (Stickel+, 1996)
J/A+AS/124/259 : Westerbork Northern Sky Survey I. (Rengelink+ 1997)
J/A+AS/131/303 : GHz-Peaked-Spectrum radio sources (Stanghellini+ 1998)
J/A+A/342/378 : 6 and 20cm flux densities of radio galaxies (Gurvits+ 1999)
J/ApJS/128/17 : VLBA obs. of radio reference frame sources III. (Fey+, 2000)
J/ApJS/131/95 : VSOP 5 GHz continuum survey (Fomalont+, 2000)
J/A+A/369/380 : CSS/GPS radio sources VLA observations (Fanti+, 2001)
J/A+A/386/97 : Parkes quarter-Jansky flat-spectrum sample (Jackson+, 2002)
J/other/NewA/11.27 : 2MASS observation of BL Lac objects (Chen+, 2005)
J/AJ/130/1345 : Optical-infrared colors of CORALS QSOs (Ellison+, 2005)
J/AJ/130/1389 : Linear polarization of AGN jets at 15GHz (Lister+, 2005)
J/MNRAS/368/1411 : Flat-spectrum symmetric radio sources (Augusto+, 2006)
J/ApJ/636/610 : Damped Lyα systems at z<1.65 (Rao+, 2006)
J/ApJ/664/53 : UV photometry of GALEX QSO candidates (Atlee+, 2007)
J/ApJS/171/61 : All-Sky Survey of Flat-Spectrum Rad. Sources (Healey+, 2007)
J/A+A/463/97 : Optical observations of GPS radio sources (Labiano+, 2007)
J/ApJS/175/97 : CGRaBS: survey of γ-ray blazar cand. (Healey+, 2008)
J/AJ/136/580 : Sixth VLBA calibrator survey: VCS6 (Petrov+, 2008)
J/AJ/138/845 : BVRI observations of 235 bright quasars (Ojha+, 2009)
J/MNRAS/440/696 : HI absorption in nearby radio galaxies (Allison+, 2014)
J/A+A/575/A44 : HI absorption in flux-selected radio AGNs (Gereb+, 2015)
J/MNRAS/462/4197 : HI 21-cm absorption in redshifted galaxies (Curran+, 2016)
J/AJ/151/74 : VLA/VLBA obscured radio-loud AGN (Yan+, 2016)
J/A+A/604/A43 : HI in nearby radio sources (Maccagni+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- ID Source identifier
18- 19 I2 h RAh Hour of Right Ascension (J2000)
21- 22 I2 min RAm Minute of Right Ascension (J2000)
24- 27 F4.1 s RAs Second of Right Ascension (J2000)
29 A1 --- DE- Sign of the Declination (J2000)
30- 31 I2 deg DEd Degree of Declination (J2000)
33- 34 I2 arcmin DEm Arcminute of Declination (J2000)
36- 39 F4.1 arcsec DEs Arcsecond of Declination (J2000)
41- 48 F8.6 --- z [0.017/3.8] Optical redshift
50- 57 F8.6 --- e_z [9e-06/0.01]? Uncertainty in z
59- 66 F8.3 MHz nuHI [297/1396] Expected frequency of HI 21cm line
68- 72 F5.3 MHz e_nuHI [0.01/3]? Uncertainty in nuHI
74- 77 I4 s HItime [164/3583]? Total HI integration time
79- 82 I4 s OHtime [149/3583]? Total OH integration time
84- 90 A7 --- Class Radio source cassification (1)
92- 98 A7 --- r_Class Classification reference code(s) (2)
100 I1 --- Refsp [1/5]? Previous HI spectrum reference code (3)
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Note (1): Classification as follows:
GPS = GHz-Peaked Spectrum;
CSS = Compact Steep-Spectrum;
CSO = Compact Symmetric Objects;
FSRS = Flat-Spectrum Radio Sources (82 occurrences).
Note (2): Classification reference code as follows:
1 = de Vries, Barthel, & O'Dea (1997A&A...321..105D 1997A&A...321..105D);
2 = Healey et al. (2007ApJS..171...61H 2007ApJS..171...61H);
3 = O'Dea & Baum (1997ApJ...113..148O 1997ApJ...113..148O);
4 = Peck & Taylor (2000ApJ...534...90P 2000ApJ...534...90P);
5 = Fanti et al. (1990A&A...231..333F 1990A&A...231..333F);
6 = Spencer et al. (1989MNRAS.240..657S 1989MNRAS.240..657S);
7 = Morganti et al. (1997MNRAS.284..541M 1997MNRAS.284..541M);
8 = Augusto et al. (2006MNRAS.368.1411A 2006MNRAS.368.1411A);
9 = Condon et al. (1977AJ.....82..692C 1977AJ.....82..692C);
10 = Xiang et al. (2005A&A...434..123X 2005A&A...434..123X);
11 = Jackson et al. (2002A&A...386...97J 2002A&A...386...97J);
12 = Fomalont et al. (2000ApJS..131...95F 2000ApJS..131...95F);
13 = Gelderman & Whittle (1994ApJS...91..491G 1994ApJS...91..491G).
Note (3): Spectrum reference code as follows:
1 = Carilli et al. (1998ApJ...498..175C 1998ApJ...498..175C);
2 = Vermeulen et al. (2003A&A...404..861V 2003A&A...404..861V);
3 = Gupta et al. (2006MNRAS.373..972G 2006MNRAS.373..972G);
4 = Ishwara-Chandra et al. (2003JApA...24...37I 2003JApA...24...37I);
5 = Curran et al. (2013MNRAS.428.2053C 2013MNRAS.428.2053C).
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- ID Source identifier
18- 25 F8.6 --- z [0.017/3.8] Optical redshift
27- 34 F8.6 --- e_z [9e-06/0.008]? Uncertainty in z
36- 43 F8.3 MHz nu [297.5/1396] HI absorption line centroid
or expected frequency
45- 49 F5.3 MHz e_nu [0.01/3]? Uncertainty in nu
51- 56 I6 km/s Blue [-12690/-327]? Blue velocity range limit
58- 62 I5 km/s Red [20/26560]? Red velocity range limit
64- 68 F5.2 --- rms [1.8/49]? Spectral rms noise in search region
70- 70 A1 --- f_rms [R] R= Radio Frequency Interference
72- 79 F8.5 Jy Ctnm [0.1/46.7]? Continuum flux density at expected
redshifted line
81- 87 F7.5 Jy e_Ctnm [2e-05/3.6]? Uncertainty in Ctnm
89- 89 A1 --- l_NHI The 3σ limit flag on NHI
90- 95 F6.3 10+20/cm2 NHI [0.01/74]? Measured H I column density
97-100 F4.1 10+20/cm2 e_NHI [0.4/13]? Uncertainty in NHI
102-102 A1 --- l_P-NHI The 3σ limit flag on P-NHI
103-108 F6.3 10+20/cm2 P-NHI [0.08/81]? Previously measured
HI column density
110-111 I2 --- r_P-NHI [1/10]? Flag on P-NHI (4)
113-116 F4.1 10+20/cm2 e_P-NHI [1.3/17]? Uncertainty in P-NHI
118-123 F6.4 arcsec ASize [0.0004/9.2]? Largest projected angular size
125-132 F8.5 kpc PSize [0.001/64.5]? Linear size
134-135 I2 --- Refc [1/17]? Continuum source characteristics
reference code (5)
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Note (4): HI reference code as follows:
1 = Carilli et al. (1998ApJ...498..175C 1998ApJ...498..175C);
2 = Vermeulen et al. (2003A&A...404..861V 2003A&A...404..861V);
3 = Gupta et al. (2006MNRAS.373..972G 2006MNRAS.373..972G);
4 = Ishwara-Chandra et al. (2003JApA...24...37I 2003JApA...24...37I);
5 = Curran et al. (2013MNRAS.428.2053C 2013MNRAS.428.2053C);
6 = Aditya & Kanekar (2018MNRAS.481.1578A 2018MNRAS.481.1578A);
7 = Aditya & Kanekar (2018MNRAS.473...59A 2018MNRAS.473...59A);
8 = Curran et al. (2017MNRAS.470.4600C 2017MNRAS.470.4600C) and RFI;
9 = Curran et al. (2019MNRAS.484.1182C 2019MNRAS.484.1182C);
10 = Aditya et al. (2016MNRAS.455.5000A 2016MNRAS.455.5000A).
Note (5): Reference code as follows:
1 = Stanghellini et al. (1990A&A...233..379S 1990A&A...233..379S);
2 = Gurvits et al. (1999A&A...342..378G 1999A&A...342..378G);
3 = Gupta et al. (2006MNRAS.373..972G 2006MNRAS.373..972G);
4 = Fomalont et al. (2000ApJS..131...95F 2000ApJS..131...95F);
5 = O'Dea & Baum (1997ApJ...113..148O 1997ApJ...113..148O);
6 = Xu et al. (1995ApJS...99..297X 1995ApJS...99..297X);
7 = Fey & Charlot (2000ApJS..128...17F 2000ApJS..128...17F);
8 = Menon (1983AJ.....88..598M 1983AJ.....88..598M);
9 = Murphy et al. (1993MNRAS.264..298M 1993MNRAS.264..298M);
10 = Antonucci & Ulvestad (1985ApJ...294..158A 1985ApJ...294..158A);
11 = Shen et al. (1998AJ....115.1357S 1998AJ....115.1357S);
12 = Fanti et al. (2001A&A...369..380F 2001A&A...369..380F);
13 = Fey & Charlot (1997ApJS..111...95F 1997ApJS..111...95F);
14 = Xiang et al. (2005A&A...434..123X 2005A&A...434..123X);
15 = Shen et al. (1997AJ....114.1999S 1997AJ....114.1999S);
16 = Fanti et al. (1990A&A...231..333F 1990A&A...231..333F);
17 = Morganti, Killeen, & Tadhunter (1993MNRAS.263.1023M 1993MNRAS.263.1023M).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- ID Source identifier
18- 24 F7.5 --- z [0.15/3.8] Optical redshift
26- 32 F7.2 MHz nu1612 [337.7/1398.8] Expected frequency of
1612MHz line
34- 39 I6 km/s Blue1612 [-10741/-93]? Blue velocity range limit
of 1612MHz line
41- 45 I5 km/s Red1612 [760/13121]? Red velocity range limit
of 1612MHz line
47- 51 F5.2 mJy rms1612 [2/18]? Spectral rms noise around
1612MHz line
53 A1 --- f_rms1612 [R] R: Radio Frequency Interference
55- 61 F7.2 MHz nu1667 [349.3/1446.6] Expected frequency of
1667MHz line
63- 68 I6 km/s Blue1667 [-10496/-83]? Blue velocity range limit
of 1667MHz line
70- 74 I5 km/s Red1667 [270/12882]? Red velocity range limit
of 1667MHz line
76- 80 F5.2 mJy rms1667 [1.5/19.1]? Spectral rms noise around
1667MHz line
82 A1 --- f_rms1667 [R] R: Radio Frequency Interference
84- 90 F7.2 MHz nu1720 [360.4/1492.7] Expected frequency of
1720MHz line
92- 97 I6 km/s Blue1720 [-12972/-42]? Blue velocity range limit
of 1720MHz line
99-103 I5 km/s Red1720 [142/9330]? Red velocity range limit
of 1720MHz line
105-109 F5.2 mJy rms1720 [1.9/18.2]? Spectral rms noise around
1720MHz line
111 A1 --- f_rms1720 [R] R: Radio Frequency Interference
113-120 F8.5 mJy Cntm [0.1/45]? Expected continuum flux at
redshifted 1667MHz OH line
122-128 F7.5 mJy e_Cntm [2e-05/3]? Uncertainty in Cntm
130 A1 --- f_Cntm [ab] Flag on Cntm (1)
132 A1 --- l_NOH/Tx The 3σ limit flag on NOH/Tx
133-139 F7.2 10+13/cm2/K NOH/Tx [0.3/1640]? Column density of expected
redshifted 1670MHz OH line
141 A1 --- f_NOH/Tx [ab] Flag on NOH/Tx (1)
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Note (1): Flag as follows:
a = Since the 1667 (and 1665) MHz line was not observable due to RFI, we
use the 1612MHz line to obtain an upper limit on the OH column
density. The interpolated continuum corresponds to the redshifted
frequency of this line.
b = The interpolated continuum and OH column density limit are based on
the 1720MHz OH line.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Mar-2020