J/ApJ/678/96 Extragalactic H2O masers (Braatz+, 2008)
The discovery of water maser emission from eight nearby galaxies.
Braatz J.A., Gugliucci N.E.
<Astrophys. J., 678, 96-101 (2008)>
=2008ApJ...678...96B 2008ApJ...678...96B
ADC_Keywords: Active gal. nuclei ; Masers ; Radio sources ; Radial velocities
Keywords: galaxies: active - galaxies: nuclei - galaxies: Seyfert -
ISM: molecules - masers - radio lines: galaxies
Abstract:
Using the Green Bank Telescope, we conducted a "snapshot" survey for
water maser emission toward the nuclei of 611 galaxies and detected
eight new sources. The sample consisted of nearby (v<5000km/s) and
luminous (MB←19.5) galaxies, some with known nuclear activity but
most not previously known to host AGNs. Our detections include both
megamasers associated with AGNs and relatively low luminosity masers
probably associated with star formation. The detection in UGC 3789 is
particularly intriguing because the spectrum shows both systemic and
high-velocity lines indicative of emission from an AGN accretion disk
seen edge-on. Based on 6 months of monitoring, we detected
accelerations among the systemic features ranging from 2 to 8km/s/yr,
the larger values belonging to the most redshifted systemic
components. High-velocity maser lines in UGC 3789 show no detectable
drift over the same period. Although UGC 3789 was not known to be an
AGN prior to this survey, the presence of a disk maser is strong
evidence for nuclear activity, and an optical spectrum obtained later
has confirmed it. With follow-up observations, it may be possible to
measure a geometric distance to UGC 3789.
Description:
We conducted observations between 2005 September 27 and 2007 April 14
using the Green Bank Telescope (GBT) of the National Radio Astronomy
Observatory.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 58 8 H2O masers detected during the Green Bank Telescope
(GBT) survey
table2.dat 98 648 Galaxies surveyed for water maser emission but
not detected
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See also:
J/AJ/132/1322 : Water maser survey (Gomez+, 2006)
J/ApJ/658/1096 : H2O maser classification (Deacon+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name NGC or UGC Source
10- 11 I2 h RAh Hour of right ascension (J2000)
13- 14 I2 min RAm Minute of right ascension (J2000)
16- 19 F4.1 s RAs Second of right ascension (J2000)
21 A1 --- DE- Declination sign (J2000)
22- 23 I2 deg DEd Degree of right ascension (J2000)
25- 26 I2 arcmin DEm Arcminute of right ascension (J2000)
28- 29 I2 arcsec DEs Arcsecond of right ascension (J2000)
31- 34 I4 km/s HVel Heliocentric recession velocity from NED
36- 37 I2 km/s e_HVel HVel uncertainty
39- 41 I3 mJy Speak Peak flux density
43- 47 F5.1 solLum Liso Inferred isotropic luminosity of the
maser emission
49- 58 A10 "YYYY/MM/DD" ObsDate Date of observation
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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- 13 A13 --- Name Source name
15- 16 I2 h RAh Hour of Right Ascension (J2000)
18- 19 I2 min RAm Minute of Right Ascension (J2000)
21- 25 F5.2 s RAs Second of Right Ascension (J2000)
27 A1 --- DE- Sign of the Declination (J2000)
28- 29 I2 deg DEd Degree of Declination (J2000)
31- 32 I2 arcmin DEm Arcminute of Declination (J2000)
34- 37 F4.1 arcsec DEs Arcsecond of Declination (J2000)
39- 43 I5 km/s Vel Recession velocity
45- 54 A10 "YYYY/MM/DD" ObsDate Date of the observation
56- 60 F5.1 K Temp System temperature from first spectral window
62- 63 I2 min Time Integration time
65- 68 F4.1 mJy rms1 RMS noise from first spectral window (1)
70- 74 I5 km/s V1low Lower velocity range covered by first window
76- 80 I5 km/s V1hi Upper velocity range covered by first window
82- 86 F5.1 mJy rms2 RMS noise from second spectral windown (1)
88- 92 I5 km/s V2low Lower velocity range covered by second window
94- 98 I5 km/s V2hi Upper velocity range covered by second window
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Note (1): After Hanning smoothing.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 16-Sep-2010