J/ApJ/752/45 SPLASH: Stellar spectroscopy of M31 satellites (Tollerud+, 2012)
The SPLASH Survey: spectroscopy of 15 M31 dwarf spheroidal satellite galaxies.
Tollerud E.J., Beaton R.L., Geha M.C., Bullock J.S., Guhathakurta P.,
Kalirai J.S., Majewski S.R., Kirby E.N., Gilbert K. M., Yniguez B.,
Patterson R.J., Ostheimer J.C., Cooke J., Dorman C.E., Choudhury A.,
Cooper M.C.
<Astrophys. J., 752, 45 (2012)>
=2012ApJ...752...45T 2012ApJ...752...45T
ADC_Keywords: Photometry ; Radial velocities ; Equivalent widths ;
Galaxies, nearby
Keywords: dark matter - galaxies: dwarf - galaxies: fundamental parameters -
galaxies: individual (And I, And III, And V, And VII, And IX, And X) -
galaxies: individual (And XI, And XII, And XIII, And XIV, And XV) -
galaxies: individual (And XVI, And XVIII, And XXI, And XXII) -
galaxies: kinematics and dynamics - Local Group
Abstract:
We present a resolved star spectroscopic survey of 15 dwarf spheroidal
(dSph) satellites of the Andromeda galaxy (M31). We filter foreground
contamination from Milky Way (MW) stars, noting that MW substructure
is evident in this contaminant sample. We also filter M31 halo field
giant stars and identify the remainder as probable dSph members. We
then use these members to determine the kinematical properties of the
dSphs. For the first time, we confirm that And XVIII, XXI, and XXII
show kinematics consistent with bound, dark-matter-dominated galaxies.
From the velocity dispersions for the full sample of dSphs we
determine masses, which we combine with the size and luminosity of the
galaxies to produce mass-size-luminosity scaling relations. With these
scalings we determine that the M31 dSphs are fully consistent with the
MW dSphs, suggesting that the well-studied MW satellite population
provides a fair sample for broader conclusions. We also estimate dark
matter halo masses of the satellites and find that there is no sign
that the luminosity of these galaxies depends on their dark halo mass,
a result consistent with what is seen for MW dwarfs. Two of the M31
dSphs (And XV, XVI) have estimated maximum circular velocities smaller
than 12 km/s (to 1σ), which likely places them within the
lowest-mass dark matter halos known to host stars (along with Bootes I
of the MW). Finally, we use the systemic velocities of the M31
satellites to estimate the mass of the M31 halo, obtaining a virial
mass consistent with previous results.
Description:
We provide an overview of the M31 satellite system in Figure 1. We
present 33 DEIMOS slitmasks covering 15 of M31's dSphs, with mask
details provided in Table 1. Eight of these masks have been presented
elsewhere: the And I and III masks were previously presented in
Kalirai et al. (2010ApJ...711..671K 2010ApJ...711..671K), the And X data set was
originally published by Kalirai et al. (2009ApJ...705.1043K 2009ApJ...705.1043K), and two
masks of And XIV were described by Majewski et al.
(2007ApJ...670L...9M 2007ApJ...670L...9M). There is an additional series of Spectroscopic
and Photometric Landscape of Andromeda's Stellar Halo (SPLASH)
slitmasks for And II that will be described in a forthcoming paper (N.
Ho et al. 2012ApJ...758..124H 2012ApJ...758..124H).
Our imaging is primarily in the Washington system (specifically, the M
and T2 filters). We selected stars for spectroscopic follow-up from
catalogs generated from this imaging. The spectroscopic setup for the
DEIMOS observations provides spectral coverage over a range of
6400-9100Å (for objects centered in the mask along the dispersion
direction), with an FWHM resolution of ∼1.3Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 51 33 Observed DEIMOS slitmasks
table2.dat 90 528 SPLASH M31 dwarf spheroidal (dSph) stars
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See also:
J/ApJ/736/146 : Radial velocities of stars in Bootes I (Koposov+, 2011)
J/A+A/509/A61 : Long slit spectroscopy in M31 (Saglia+, 2010)
J/ApJ/704/385 : M31 integrated light abundances (Colucci+, 2009)
J/MNRAS/390/1437 : Stellar streams in Andromeda (M31) (Chapman+, 2008)
J/MNRAS/369/120 : Kinematic survey of PNe in M31 (Merrett+, 2006)
J/AJ/129/2232 : Variable stars in And I and And III (Pritzl+, 2005)
J/AJ/127/318 : BV photometry of Andromeda II variables (Pritzl+, 2004)
J/AJ/124/1464 : Variable stars in Andromeda VI (Pritzl+, 2002)
J/A+AS/127/409 : New nearby dwarf galaxy candidates list (Karachentseva+ 1998)
J/AJ/106/986 : CMD for And III (Armandroff+, 1993)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [And]
5- 9 A5 --- Sat Andromeda Satellite identification (I to XXII)
11- 16 A6 --- Mask Mask name on which star observed
18- 25 F8.2 d MJD Modified Julian Date
27- 37 A11 "Y/M/D" Date UTC observation date
39- 43 I5 s Exp [1800/10800] Total exposure time
45- 47 I3 --- Nslit [62/152] Number of slits
49- 51 I3 --- NVel [6/110] Number of successful velocities (1)
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Note (1): While for some masks there is an apparently low percentage of
successful velocities, this is due to higher fractions of filler
targets in the sparser fields that tend to have lower odds of being
RGB stars. This is discussed in detail in Section 3.1.
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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- 6 A6 --- Mask Mask name on which star observed; see Table 1
9-16 I8 --- Seq [992/60102604] Star ID number;
unique within a dSph field
18-19 I2 h RAh [0/23] Hour of Right Ascension (J2000)
21-22 I2 min RAm Minute of Right Ascension (J2000)
24-28 F5.2 s RAs Second of Right Ascension (J2000)
30 A1 --- DE- [+] Sign of the Declination (J2000)
31-32 I2 deg DEd [28/50] Degree of Declination (J2000)
34-35 I2 arcmin DEm Arcminute of Declination (J2000)
37-40 F4.1 arcsec DEs Arcsecond of Declination (J2000)
42-47 F6.3 mag T2mag [19.5/23.1] Washington T2 band magnitude;
extinction corrected
49-53 F5.3 mag e_T2mag [0.007/0.2] Uncertainty in T2mag
55-58 F4.2 mag M-T2 [0.8/2.3] Washington (M-T2) color index;
extinction corrected
60-63 F4.2 mag e_M-T2 [0.02/0.2] Uncertainty in M-T2
65-70 F6.1 km/s HRV [-530/-116] Heliocentric radial velocity
72-75 F4.1 km/s e_HRV [1/24] Uncertainty in HRV
77-80 F4.1 0.1nm EW [-4/2.2] Equivalent width of NaI 8190 feature;
in units of Angstroms
82-84 F3.1 0.1nm e_EW [0/5] Uncertainty in EW
86-90 F5.3 --- Mmb [0/1] Membership probability (1)
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Note (1): Computed following Equation 1 (see Section 3.2).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 21-Jan-2014