J/ApJ/907/85 The SAGA Survey. II. Satellite systems around galaxies (Mao+, 2021)
The SAGA Survey.
II. Building a Statistical Sample of Satellite Systems around Milky Way-like
Galaxies.
Mao Y.-Y., Geha M., Wechsler R.H., Weiner B., Tollerud E.J., Nadler E.O.,
Kallivayalil N.
<Astrophys. J., 907, 85 (2021)>
=2021ApJ...907...85M 2021ApJ...907...85M
ADC_Keywords: Surveys; Galaxies; Spectra, optical; Stars, masses;
Radial velocities
Keywords: Redshift surveys ; Dwarf galaxies ; Luminosity function ;
Galaxy physics ; Galaxy dark matter halos
Abstract:
We present the Stage II results from the ongoing Satellites Around
Galactic Analogs (SAGA) Survey. Upon completion, the SAGA Survey will
spectroscopically identify satellite galaxies brighter than Mr,o=-12.3
around 100 Milky Way (MW) analogs at z∼0.01. In Stage II, we have more
than quadrupled the sample size of Stage I, delivering results from
127 satellites around 36 MW analogs with an improved target selection
strategy and deep photometric imaging catalogs from the Dark Energy
Survey and the Legacy Surveys. We have obtained 25372 galaxy
redshifts, peaking around z=0.2. These data significantly increase
spectroscopic coverage for very low redshift objects in 17<ro< 20.75
around SAGA hosts, creating a unique data set that places the Local
Group in a wider context. The number of confirmed satellites per
system ranges from zero to nine and correlates with host galaxy and
brightest satellite luminosities. We find that the number and
luminosities of MW satellites are consistent with being drawn from the
same underlying distribution as SAGA systems. The majority of
confirmed SAGA satellites are star-forming, and the quenched fraction
increases as satellite stellar mass and projected radius from the host
galaxy decrease. Overall, the satellite quenched fraction among SAGA
systems is lower than that in the Local Group. We compare the
luminosity functions and radial distributions of SAGA satellites with
theoretical predictions based on cold dark matter simulations and an
empirical galaxy-halo connection model and find that the results are
broadly in agreement.
Description:
In this work, we present the Stage II results from the ongoing SAGA
Survey, including 36 spectroscopically complete satellite systems
around MW analogs.
Stage II of our survey includes redshifts taken with the fiber-based
MMT/Hectospec between 2017 May and 2019 October. The MMT/Hectospec
deploys 300 fibers over a 1deg diameter field. We used Hectospec with
the 270lines/mm grating, resulting in wavelength coverage of
3650-9200Å and spectral resolution of 1.2Å/pixel (R∼1000).
Stage II of our survey includes redshifts taken with the fiber-based
AAT/2dF observations between 2018 June and 2020 May. The AAT/2dF
deploys 400 fibers over a 2deg diameter field. We used the 580V and
385R gratings in the blue and red arms, respectively, both providing a
resolution of R=1300 over a maximum wavelength range of 3700-8700Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 77 36 *List of host galaxies in 36 complete SAGA systems
table3.dat 96 127 List of 127 satellites in 34 complete SAGA systems
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Note on table2.dat: Host galaxy properties taken from HyperLEDA, EDD,
and 2MRS; distances for some hosts were taken from the NSA catalog
(see Section 2.1.1 for detail).
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See also:
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
II/357 : The Dark Energy Survey (DES) Data Release 1 (Abbott+, 2018)
VII/203 : Las Campanas Redshift Survey (Shectman+ 1996)
VII/250 : The 2dF Galaxy Redshift Survey (2dFGRS) (2dFGRS Team, 1998-2003)
VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)
J/AJ/130/873 : Properties of BQS objects in the SDSS DR3 area (Jester+, 2005)
J/ApJS/199/26 : The 2MASS Redshift Survey (2MRS) (Huchra+, 2012)
J/AJ/144/4 : Properties of dwarf galaxies in Local Group (McConnachie+,2012)
J/ApJ/744/44 : Hα and UV fluxes in nearby galaxies (Weisz+, 2012)
J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)
J/MNRAS/435/1928 : Dwarf galaxy planes in Local Group (Pawlowski+, 2013)
J/MNRAS/474/3875 : Galaxy And Mass Assembly (GAMA) DR3 (Baldry+, 2018)
J/MNRAS/474/4151 : WiggleZ Dark Energy Survey final DR (Drinkwater+, 2018)
J/ApJ/857/104 : Low surface brightness galaxies from HSC-SSP (Greco+, 2018)
J/ApJ/861/49 : ALFALFA extragalactic HI source catalog (Haynes+, 2018)
J/MNRAS/478/5336 : z-low satellite galaxies in COSMOS survey (Xi+, 2018)
J/ApJS/244/24 : z=0 Multiwavelength Galaxy Synthesis (z0MGS). I. (Leroy+, 2019)
J/A+A/629/A18 : Deep VI photometry 15 dwarf galaxy candidates (Mueller+, 2019)
J/MNRAS/491/3496 : Andromeda XIX member stars (Collins+, 2020)
J/ApJ/893/47 : Milky Way satellite census. I. DES & PS1 (Drlica-Wagner+, 2020)
J/ApJ/895/32 : Zwicky Transient Facility BTS. I. (Fremling+, 2020)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Gal Host galaxy, common name
13- 25 A13 --- SAGA SAGA name
27- 33 F7.3 deg RAdeg [20/355] Right Ascension (J2000)
35- 41 F7.3 deg DEdeg [-60/53] Declination (J2000)
43- 46 I4 km/s RVel [1659/2865] Heliocentric radial velocity
48- 51 F4.1 Mpc Dist [25.3/39.8] Distance
53- 58 F6.2 mag KMAG [-24.6/-23] Absolute, dereddened K-band magnitude
60- 62 A3 --- Pcov Photometric coverage (1)
64- 68 F5.1 % Scov [80/100] Spectroscopic coverage, within the SAGA
primary targeting region
70- 70 I1 --- Nsat [0/9] Number of confirmed satellites (2)
72- 72 I1 --- Fsat [0/1] Number of satellites below mag. limit (2)
74- 77 F4.2 --- Psat [0.06/2.54] Unconfirmed potential satellites (2)
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Note (1): Existing coverage by photometric surveys, S for SDSS, D for DES,
and L for Legacy Survey.
Note (2): The confirmed satellites, potential satellites and faint satellites
are relative to an absolute magnitude limit of Mr,o=-12.3
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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- 11 A11 --- Gal Host galaxy, common name
13- 31 A19 --- objID Object ID (1)
33- 40 F8.4 deg RAdeg [20/355] Right Ascension (J2000) (1)
42- 49 F8.4 deg DEdeg [-60/54] Declination (J2000) (1)
51- 53 I3 kpc Dist [15/298] Projected distance to the host galaxy
55- 58 I4 km/s dRVel [-259/259] Difference in heliocentric velocity,
satellite-host
60- 64 F5.2 mag rmag [12.7/21.7] dereddened r-band magnitude (1)
66- 70 F5.1 mag RMAG [-20.2/-10.7] k-corrected, absolute r-band
magnitude (2)
72- 75 F4.2 mag g-r [0.06/0.69] dereddened, g-r color (1)
77- 81 F5.2 mag/arcs2 mu [19.4/25.8] effective surface brightness (1)
83- 87 F5.2 [Msun] Mass [5.65/10.1] log, stellar mass (3)
89- 89 A1 --- Ha [YN] Presence of the Hα>2Angstroms
91- 96 A6 --- Ref Redshift source (4)
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Note (1): Photometric properties taken from the primary survey
(Geha+, 2017ApJ...847....4G 2017ApJ...847....4G)
Note (2): the same physical distance as the host galaxy.
Note (3): k-corrected, absolute r-band magnitude, assuming the object is at the
same distance as the host galaxy.
Note (4): Redshift source; the AAT/MMT/PAL labels indicate the redshift was
first obtained by SAGA.
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History:
From electronic version of the journal
References:
Geha et al. Paper I : 2017ApJ...847....4G 2017ApJ...847....4G
(End) Prepared by [AAS], Coralie Fix [CDS], 01-Jun-2022