J/MNRAS/469/347 Extremely Isolated Galaxies. II. (Spector+, 2017)
EIG. II. Intriguing characteristics of the most extremely isolated galaxies.
Spector O., Brosch N.
<Mon. Not. R. Astron. Soc., 469, 347-382 (2017)>
=2017MNRAS.469..347S 2017MNRAS.469..347S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Photometry, SDSS ; Photometry, UBVRI ;
Photometry, ultraviolet ; Photometry, infrared ; H I data
Keywords: surveys - galaxies: evolution - galaxies: haloes -
galaxies: star formation - galaxies: structure
Abstract:
We have selected a sample of 41 extremely isolated galaxies (EIGs)
from the local Universe using both optical and HI Arecibo Legacy Fast
ALFA survey redshifts. Narrow-band Hα and wide-band imaging
along with public data were used to derive star formation rates
(SFRs), star formation histories and morphological classifications for
the EIGs. We have found that the extreme isolation of the EIGs does
not affect considerably their star formation compared to field
galaxies. EIGs are typically 'blue cloud' galaxies that fit the 'main
sequence of star-forming galaxies' and may show asymmetric star
formation and strong compact star-forming regions. We discovered
surprising environmental dependences of the HI content, MHI, and of
the morphological type of EIGs; the most isolated galaxies (of
subsample EIG-1) have lower MHI on average (with 2.5σ
confidence) and a higher tendency to be early types (with 0.94
confidence) compared to the less isolated galaxies of subsample EIG-2.
To the best of our knowledge, this is the first study that finds an
effect in which an isolated sample shows a higher fraction of early
types compared to a less isolated sample. Both early-type and
late-type EIGs follow the same colour-to-M*, SFR-to-M* (main
sequence) and MHI-to-M* relations. This indicates that the
mechanisms and factors governing star formation, colour and the
MHI-to-M* relation are similar in early-type and late-type EIGs,
and that the morphological type of EIGs is not governed by their MHI
content, colour or SFR.
Description:
We have chosen the sample of EIGs using a simple isolation criterion:
a galaxy is considered an EIG and is included in the sample if it has
no known neighbours closer than a certain neighbour distance limit in
3D redshift space (200 or 300km/s as explained below) and if its
redshift is in the range 2000<cz<7000km/s. No magnitude, HI mass or
size limit was used in the selection of candidate neighbours.
Optical observations were performed using the 1-m (40 inch) telescope
of the WO. EIGs were imaged using wide band Bessell U, B, V, R and I
filters and a set of narrow-band rest-frame Hα filters for
various redshifts.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 82 41 EIG sub-samples (from Paper I)
table2.dat 72 39 Apparent SDSS magnitudes
table3.dat 68 8 Apparent UBVRI magnitudes
table4.dat 13 31 Morphological classification of the EIGs
table5.dat 27 31 GALEX apparent magnitudes
table6.dat 38 11 2MASS apparent magnitudes
table7.dat 41 32 ALFALFA HI data
table8.dat 80 32 SF measurements
table11.dat 16 37 Modelled stellar mass
table12.dat 66 21 Dynamic mass
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See also:
VII/82 : Catalogue of Isolated Galaxies (Karachentseva+, 1986)
J/A+A/411/381 : CO observation of isolated galaxies (Sauty+, 2003)
J/AJ/129/2062 : SDSS DR1 isolated galaxies (Allam+, 2005)
J/MNRAS/434/336 : Nuclear activity in isolated galaxies
(Hernandez-Ibarra+, 2013)
J/AJ/139/2525 : UNAM-KIAS catalog of isolated galaxies
(Hernandez-Toledo+, 2010)
J/ApJ/788/L39 : AMIGA galaxies structural parameters (Fernandez+, 2014)
J/A+A/436/443 : AMIGA. I. Velocities of CIG galaxies
(Verdes-Montenegro+, 2005)
J/A+A/449/937 : AMIGA. II. Morphological refinement (Sulentic+, 2006)
J/A+A/462/507 : AMIGA. III. IRAS data (Lisenfeld+, 2007)
J/A+A/470/505 : AMIGA. IV. Neighbours around CIG galaxies (Verley+, 2007)
J/A+A/485/475 : AMIGA. VI. Radio fluxes of the isolated galaxies
(Leon+, 2008)
J/A+A/486/73 : AMIGA. VII. FIR and radio study (Sabater+, 2008)
J/A+A/532/A117 : AMIGA. VIII. Flux ratio asymmetry parameter (Espada+, 2011)
J/A+A/534/A102 : AMIGA. IX. Molecular gas properties (Lisenfeld+, 2011)
J/A+A/540/A47 : AMIGA. X. Isolated galaxy colors (Fernandez+, 2012)
J/A+A/545/A15 : AMIGA. XI. Optical nuclear activity (Sabater+, 2012)
J/A+A/560/A9 : AMIGA. Revision of the isolation degree
(Argudo-Fernandez+, 2013)
J/A+A/609/A17 : AMIGA XIII. HI properties (Jones+, 2018)
Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [EIG]
5- 9 A5 --- EIG EIG designation (1)
11- 34 A24 --- Name NED Name
37- 53 A17 --- ALFALFA ALFALFA name (HIHHMMSS.s+DDMMSS)
55- 56 I2 h RAh Right ascension (J2000)
58- 59 I2 min RAm Right ascension (J2000)
61- 64 F4.1 s RAs Right ascension (J2000)
66 A1 --- DE- Declination sign (J2000)
67- 68 I2 deg DEd Declination (J2000)
70- 71 I2 arcmin DEm Declination (J2000)
73- 74 I2 arcsec DEs Declination (J2000)
76- 79 I4 km/s cz Heliocentric radial velocity
81- 82 I2 km/s e_cz Heliocentric radial velocity error
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Note (1): Subsamples as follows:
EIG-1s subsample = Spring region galaxies with no neighbours closer
than 3h-1Mpc in both NED and ALFALFA data
EIG-1a subsample = Autumn region galaxies with no neighbours closer
than 3h-1Mpc in both NED and ALFALFA data
EIG-2s subsample = Spring region galaxies with no neighbours closer
than 3h-1Mpc in NED data, but some in ALFALFA data
EIG-2a subsample = Autumn region galaxies with no neighbours closer
than 3h-1Mpc in NED data, but some in ALFALFA data
EIG-3s subsample = Spring region galaxies, for which the closest neighbour
in NED data is at a distance of 2-3h-1Mpc
EIG-3a subsample = Autumn region galaxies, for which the closest neighbour
in NED data is at a distance of 2-3h-1Mpc
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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- 5 A5 --- EIG EIG designation
7 A1 --- n_EIG [a-d] Note on EIG (1)
9- 14 F6.3 mag umag ? SDSS u magnitude
16- 20 F5.3 mag e_umag ? SDSS u magnitude error
22- 27 F6.3 mag gmag ? SDSS g magnitude
29- 33 F5.3 mag e_gmag ? SDSS g magnitude error
35- 40 F6.3 mag rmag ? SDSS r magnitude
42- 46 F5.3 mag e_rmag ? SDSS r magnitude error
48- 53 F6.3 mag imag ? SDSS i magnitude
55- 59 F5.3 mag e_imag ? SDSS i magnitude error
61- 66 F6.3 mag zmag ? SDSS z magnitude
68- 72 F5.3 mag e_zmag ? SDSS z magnitude error
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Note (1): Notes as follows:
a = No optical counterpart was found for EIG 1s-05 (an ALFALFA object)
b = EIG1s-14is projected close to a foreground bright star.
Uncertainties were estimated to be 0.1mag.
c = Converted from Landolt (UBVRI) magnitudes
d = EIG2s-06 has a significant foreground star in front of it.
Uncertainties were estimated to be 0.2mag.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- EIG EIG designation
7- 11 F5.2 mag Umag ? U magnitude
13- 16 F4.2 mag e_Umag ? U magnitude error
18- 23 F6.3 mag Bmag ? B magnitude
25- 29 F5.3 mag e_Bmag ? B magnitude error
31- 36 F6.3 mag Vmag ? V magnitude
38- 42 F5.3 mag e_Vmag ? V magnitude error
44- 49 F6.3 mag Rmag ? R magnitude
51- 55 F5.3 mag e_Rmag ? R magnitude error
57- 62 F6.3 mag Imag ? I magnitude
64- 68 F5.3 mag e_Imag ? I magnitude error
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- EIG EIG designation
7- 13 A7 --- Type Type (Late, Unknown or Early)
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- EIG EIG designation
7- 11 F5.2 mag mFUV ? FUV magnitude
13- 16 F4.2 mag e_mFUV ? FUV magnitude error
18- 22 F5.2 mag mNUV NUV magnitude
24- 27 F4.2 mag e_mNUV NUV magnitude error
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- EIG EIG designation
7- 11 F5.2 mag Jmag ? 2MASS J magnitude
13- 16 F4.2 mag e_Jmag ? 2MASS J magnitude error
18- 22 F5.2 mag Hmag ? 2MASS H magnitude
24- 27 F4.2 mag e_Hmag ? 2MASS H magnitude error
29- 33 F5.2 mag Ksmag ? 2MASS Ks magnitude
35- 38 F4.2 mag e_Ksmag ? 2MASS Ks magnitude error
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- EIG EIG designation
7- 9 I3 km/s W50 Velocity width of the HI line profile
11- 12 I2 km/s e_W50 Velocity width of the HI line profile error
14- 17 F4.2 Jy.km/s FHI Total HI line flux
19- 22 F4.2 Jy.km/s e_FHI Total HI line flux error
24- 27 F4.1 --- SNR Estimated signal-to-noise ratio of the
detection
29- 33 F5.3 [Msun] logMHI HI mass content
35- 39 F5.3 [Msun] e_logMHI HI mass content error
41 I1 --- Code [1/2] Category of the HI detection (1)
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Note (1): Category of the HI detection as follows:
1 = source of SNR and general qualities that make it a reliable detection
2 = source with SNR≲6.5 that does not qualify for code 1 but was matched
with a counterpart with a consistent optical redshift, and is very
likely to be real
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- EIG EIG designation
7- 11 F5.1 0.1nm EW Equivalent width
13- 16 F4.1 0.1nm e_EW Equivalent width error
18- 25 E8.3 mW/m2 FHa Hα flux
27- 33 E7.2 mW/m2 e_FHa Hα flux error
35 A1 --- l_W3mag Limit flag on W3mag (1)
36- 40 F5.2 mag W3mag WISE W3 magnitude
42- 45 F4.2 mag e_W3mag ? WISE W3 magnitude error
48 A1 --- l_W4mag Limit flag on W4mag (1)
49- 52 F4.2 mag W4mag WISE W4 magnitude
54- 57 F4.2 mag e_W4mag ? WISE W4 magnitude error
59 A1 --- l_fracHaext Limit flag on fracHaext
60- 63 F4.2 --- fracHaext Fraction of the total Hα flux
extinguished within the EIG
65- 68 F4.2 --- e_fracHaext ? Fraction of the total Hα flux
extinguished within the EIG
70- 74 F5.3 Msun/yr SFR Star formation rate
76- 80 F5.3 Msun/yr e_SFR Star formation rate error
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Note (1): < and > indicate 0.95 confidence level upper and lower limits
(respectively).
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Byte-by-byte Description of file: table11.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- EIG EIG designation
7- 11 F5.2 [Msun] logM* Modelled stellar mass
13- 16 F4.2 [Msun] e_logM* Modelled stellar mass error
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Byte-by-byte Description of file: table12.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- EIG EIG designation
7 A1 --- n_EIG [a] Note on EIG (1)
9- 13 F5.2 kpc a24 Semimajor axis at µR=24mag/arcsec2
15- 18 F4.2 kpc e_a24 Semimajor axis at µR=24mag/arcsec2
error
21- 25 F5.3 --- b24/a24 Semiminor axis at µR=24mag/arcsec2
27- 31 F5.3 --- e_b24/a24 Semiminor axis at µR=24mag/arcsec2
error
34- 35 I2 deg i Estimated inclination of the galaxy
37- 38 I2 deg e_i Estimated inclination of the galaxy error
40- 42 I3 km/s vrot Rotational velocity
44- 45 I2 km/s e_vrot Rotational velocity error
47- 51 F5.2 [Msun] logMdyn24 Dynamical mass (lower limit to the galactic
total mass)
53- 56 F4.2 [Msun] e_logMdyn24 Dynamical mass error
58- 61 F4.1 --- Mratio Mass ratio, Mdyn24/(M*+MHI)
63- 66 F4.1 --- e_Mratio Mass ratio, Mdyn24/(M*+MHI), error
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Note (1): a: Due to stars/galaxies projected by chance on EIG1a-03 and
interfering with the measurement b24/a24 was measured on the third largest
ellipse isophote (µR=24.93±0.08mag/arcsec2).
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History:
From electronic version of the journal
References:
Spector & Brosch, Paper I 2016MNRAS.456..885S 2016MNRAS.456..885S
(End) Patricia Vannier [CDS] 17-Mar-2020