J/ApJ/909/211 HST obs. of MADCASH-1 and MADCASH-2 (Carlin+, 2021)
Hubble Space Telescope observations of two faint dwarf satellites of nearby
LMC analogs from MADCASH.
Carlin J.L., Mutlu-Pakdil B., Crnojevic D., Garling C.T., Karunakaran A.,
Peter A.H.G., Tollerud E., Forbes D.A., Hargis J.R., Lim S.,
Romanowsky A.J., Sand D.J., Spekkens K., Strader J.
<Astrophys. J., 909, 211 (2021)>
=2021ApJ...909..211C 2021ApJ...909..211C
ADC_Keywords: Galaxies, photometry; Photometry, HST; Photometry, VRI;
Extinction; H I data
Keywords: Dwarf galaxies ; HST photometry ; H I line emission ;
Dwarf spheroidal galaxies ; Galaxy evolution ; Galaxy quenching ;
Galaxy stellar content ; Galaxy properties
Abstract:
We present a deep Hubble Space Telescope (HST) imaging study of two
dwarf galaxies in the halos of Local Volume Large Magellanic Cloud
(LMC) analogs. These dwarfs were discovered as part of our
Subaru+Hyper Suprime-Cam MADCASH survey: MADCASH-1 is a satellite of
NGC 2403 (D∼3.2Mpc), and MADCASH-2 is a previously unknown dwarf
galaxy near NGC 4214 (D∼3Mpc). Our HST data reach >3.5mag below the
tip of the red giant branch (TRGB) of each dwarf, allowing us to
derive their structural parameters and assess their stellar
populations. We measure TRGB distances
(DMADCASH-1=3.41-0.23+0.24Mpc, DMADCASH-2=3.00-0.15+0.13Mpc),
and confirm the dwarfs' associations with their host galaxies.
MADCASH-1 is a predominantly old, metal-poor stellar system (age
∼13.5Gyr, [M/H]~-2.0), similar to many Local Group dwarfs. Modelling
of MADCASH-2's color-magnitude diagram suggests that it contains
mostly ancient, metal-poor stars (age ∼13.5Gyr, [M/H]~-2.0), but that
∼10% of its stellar mass was formed 1.1-1.5Gyr ago and ∼1% was formed
400-500 Myr ago. Given its recent star formation, we search MADCASH-2
for neutral hydrogen using the Green Bank Telescope, but find no
emission and estimate an upper limit on the HI mass of
<4.8x104M☉. These are the faintest dwarf satellites known
around host galaxies of LMC mass outside the Local Group
(MV,MADCASH-1=-7.81±0.18, MV,MADCASH-2=-9.15±0.12), and one of
them shows signs of recent environmental quenching by its host. Once
the MADCASH survey for faint dwarf satellites is complete, our census
will enable us to test predictions from cold dark matter models for
hierarchical structure formation and discover the physical mechanisms
by which low-mass hosts influence the evolution of their satellites.
Description:
The MADCASH (Magellanic Analog Dwarf Companions and Stellar Halos)
project is a deep, ground-based imaging survey in which we are
systematically mapping the resolved stellar halos of nearby (D≲4Mpc)
Magellanic Cloud (MC) analogs (i.e., galaxies with stellar masses
between ∼0.1Mstar,SMC and ∼3Mstar,LMC). In this work we present
Hubble Space Telescope (HST) observations of the first two dwarf
galaxies discovered by the MADCASH survey.
We obtained HST optical observations of MADCASH-1 and MADCASH-2 using
the F606W and F814W filters on the Advanced Camera for Surveys (ACS;
HST-GO-15228; PI: J. Carlin) with a single orbit per filter per
targeted galaxy. See Section 3.
We obtained position-switched HI observations of MADCASH-2 using the
Robert C. Byrd Green Bank Telescope 20 (GBT) (AGBT19B-144;
PI: Karunakaran) with VEGAS in Mode 7 (bandwidth=11.72MHz).
See Section 4.7.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 56 4807 HST Photometry of MADCASH-1
table2.dat 56 2561 HST Photometry of MADCASH-2
table4.dat 210 2 HST-derived properties of MADCASH dwarfs
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/AJ/136/2563 : HI Nearby Galaxy Survey, THINGS (Walter+, 2008)
J/A+A/503/913 : Synthetic spectrophotometry for C-rich giants (Aringer+, 2009)
J/AJ/138/1243 : The star formation history of the LMC (Harris+, 2009)
J/AJ/138/332 : LEDA CMD/tip of the red giant branch (Jacobs+, 2009)
J/ApJ/704/898 : Photometry of the Hercules dwarf galaxy (Sand+, 2009)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)
J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)
J/ApJ/829/26 : Var. stars in the field of Andromeda XXV. III. (Cusano+, 2016)
J/ApJ/833/167 : PAndAS view of Andromeda satellites. II. (Martin+, 2016)
J/ApJ/827/89 : HST imaging of Pisces A and B (Tollerud+, 2016)
J/ApJ/868/55 : Structure of M31 halo. II. PAndAS (McConnachie+, 2018)
J/ApJ/863/25 : Deep Magellan obs. of 4 MW satellites (Mutlu-Pakdil+, 2018)
J/ApJS/244/24 : A z=0 Multiwavelength Gal. Synthesis (z0MGS). I. (Leroy+, 2019)
J/A+A/629/A18 : Deep VI photometry of 15 dwarf galaxy cand. (Mueller+, 2019)
J/ApJ/888/31 : HST/ACS observations and SFH of Antlia B (Hargis+, 2020)
J/ApJ/906/96 : Dwarfs gal. in DC Justice League Simulations (Applebaum+, 2021)
J/ApJ/907/85 : SAGA Survey. II. Satellite systems around gal. (Mao+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [0/4806] Internal index number
6- 14 F9.5 deg RAdeg [115.62/115.78] Right Ascension (J2000)
16- 24 F9.6 deg DEdeg [65.38/65.46] Declination (J2000)
26- 30 F5.2 mag F606Wmag [18.65/28.53] HST/ACS F606W filter apparent
Vega magnitude (1)
32- 35 F4.2 mag e_F606Wmag [0.01/0.3] DOLPHOT uncertainty in F606Wmag
37- 40 F4.2 mag AF606W [0.08/0.09] Galactic extinction correction
in F606W
42- 46 F5.2 mag F814Wmag [17.53/27.51] HST/ACS F814W filter apparent
Vega magnitude (1)
48- 51 F4.2 mag e_F814Wmag [0.01/0.21] DOLPHOT uncertainty in F814Wmag
53- 56 F4.2 mag AF814W [0.05/0.06] Galactic extinction correction
in F814W
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Note (1): Uncorrected for extinction.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [0/2560] Internal index number
6- 14 F9.5 deg RAdeg [182.46/182.57] Right Ascension (J2000)
16- 24 F9.6 deg DEdeg [35.42/35.5] Declination (J2000)
26- 30 F5.2 mag F606Wmag [18.67/28.48] HST/ACS F606W filter apparent
Vega magnitude (1)
32- 35 F4.2 mag e_F606Wmag [0.01/0.3] DOLPHOT uncertainty in F606Wmag
37- 40 F4.2 mag AF606W [0.03/0.04] Galactic extinction correction
in F606W
42- 46 F5.2 mag F814Wmag [17.56/27.36] HST/ACS F814W filter apparent
Vega magnitude (1)
48- 51 F4.2 mag e_F814Wmag [0.01/0.21] DOLPHOT uncertainty in F814Wmag
53- 56 F4.2 mag AF814W [0.02] Galactic extinction correction in F814W
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Note (1): Uncorrected for extinction.
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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- 9 A9 --- Name Dwarf galaxy name
11 A1 --- f_Name Flag on Name (1)
13- 20 A8 --- Host Likely host identifier
22- 23 I2 h RAh Hour of right ascension (J2000)
25- 26 I2 min RAm Minute of right ascension (J2000)
28- 32 F5.2 s RAs Second of right ascension (J2000)
34- 37 F4.2 arcsec eRA [0.5/2.5] Right ascension uncertainty
39 A1 --- DE- Sign of declination (J2000)
40- 41 I2 deg DEd Degree of declination (J2000)
43- 44 I2 arcmin DEm Arcminute of declination (J2000)
46- 50 F5.2 arcsec DEs Arcsecond of declination (J2000)
52- 55 F4.2 arcsec eDE [0.4/1.4] Declination uncertainty
57- 64 F8.4 deg RAdeg [115.66/182.53] Right ascension (J2000)
66- 72 F7.4 deg DEdeg [35.44/65.42] Declination (J2000)
74- 78 F5.2 mag F814Wmag [23.29/23.55] F814WTRGB band magnitude
80- 83 F4.2 mag e_F814Wmag [0.11/0.15] Uncertainty on the F814Wmag
85- 88 F4.2 mag E_F814Wmag [0.09/0.15] Upper uncertainty on F814Wmag
90- 94 F5.2 mag m-M [27.39/27.66] Distance modulus (2)
96- 99 F4.2 mag e_m-M [0.11/0.15] Lower uncertainty on m-M
101-104 F4.2 mag E_m-M [0.09/0.15] Upper uncertainty on m-M
106-109 F4.2 Mpc Dist [3/3.41] Distance
111-114 F4.2 Mpc e_Dist [0.15/0.23] Lower uncertainty on Dist
116-119 F4.2 Mpc E_Dist [0.13/0.24] Upper uncertainty on Dist
121-124 F4.1 --- [M/H]iso [-2] Metallicity (3)
126-130 F5.2 mag VMag [-9.15/-7.81] Absolute V-band magnitude
132-135 F4.2 mag e_VMag [0.12/0.18] VMag uncertainty
137-140 F4.1 arcsec rh [9/10.8] Half-light radius
142-144 F3.1 arcsec e_rh [0.5/1] rh uncertainty
146-150 F5.1 pc rh-pc [130.9/178.5] Rh in parsec
152-155 F4.1 pc e_rh-pc [13.5/27.5] Lower uncertainty on rh-pc
157-160 F4.1 pc E_rh-pc [13.3/30.3] Upper uncertainty on rh-pc
162-165 F4.2 --- ell [0.19/0.25] Ellipticity, ε
167-170 F4.2 --- e_ell [0.05/0.11] ell uncertainty
172-173 I2 deg theta [0/76] Position angle, θ
175-176 I2 deg e_theta [11/19] theta uncertainty
178-181 F4.1 mag/arcsec2 muV [24.8/26.7] Mean surface brightness
within rh, µV,eff (4)
183-185 F3.1 mag/arcsec2 e_muV [0.3/0.4] muV uncertainty
187-191 E5.2 Msun Mstar [180000/630000] Stellar mass (5)
193-197 E5.2 Msun e_Mstar [30000/60000] Mstar uncertainty
199 A1 --- l_MHI/LV Limit flag on MHI/LV
200-203 F4.2 Msun/Lsun MHI/LV HI mass to light ratio, MHI/LV
205 A1 --- l_MHI Limit flag on MHI
206-210 E5.2 Msun MHI HI mass
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Note (1): Flag as follows:
a = Following IAU naming conventions, this dwarf was dubbed
MADCASH J074238+652501-dw in Carlin+ (2016ApJ...828L...5C 2016ApJ...828L...5C).
b = Following the naming convention used for the first MADCASH dwarf,
this dwarf would be designated MADCASH J121007+352635-dw.
Note (2): Assuming MF814WTRGB=-4.06+0.2x(color-1.23)
(Rizzi+ 2007ApJ...661..815R 2007ApJ...661..815R), where color is the (F606W-F814W) color
of the TRGB.
Note (3): Estimated using isochrones of age 10Gyr; the reported value is
just an approximation. See text for details.
Note (4): Mean surface brightness within the (elliptical) half-light radius.
Note (5): Assuming Mstar/LV=1.6, as is typical for dwarf spheroidals (dSphs)
(Woo+ 2008MNRAS.390.1453W 2008MNRAS.390.1453W).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Aug-2022