J/A+A/689/A206 Detached tidal dwarf galaxies spectra (Zaragoza-Cardiel+, 2024)
Detection and characterization of detached tidal dwarf galaxies.
Zaragoza-Cardiel J., Smith B.J., Jones M.G., Giroux M.L., Toner S.,
Alzate J.A., Fernandez-Arenas D., Mayya Y.D., Ortiz-Leon G., Portilla M.
<Astron. Astrophys. 689, A206 (2024)>
=2024A&A...689A.206Z 2024A&A...689A.206Z (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, interacting ; Spectroscopy ; Redshifts
Keywords: galaxies: abundances - galaxies: dwarf - galaxies: evolution -
galaxies: interactions -
Abstract:
Tidal interactions between galaxies often give rise to tidal tails,
which can harbor concentrations of stars and interstellar gas
resembling dwarf galaxies. Some of these tidal dwarf galaxies (TDGs)
have the potential to detach from their parent galaxies and become
independent entities, but their long-term survival is uncertain. In
this study, we conducted a search for detached TDGs associated with a
sample of 39 interacting galaxy pairs in the local Universe using
infrared, ultraviolet, and optical images. We employed IR colors and
UV/optical/IR spectral energy distributions to identify potential
interlopers, such as foreground stars or background quasars. Through
spectroscopic observations using the Boller and Chivens spectrograph
at San Pedro Martir Observatory, we confirmed that six candidate
TDGs are at the same redshift as their putative parent galaxy pairs.
We identified and measured emission lines in the optical spectra and
calculated nebular oxygen abundances, which range from
log(O/H)=8.10±0.01 to 8.51±0.02. We have serendipitously
discovered an additional detached TDG candidate in Arp72 using
available spectra from SDSS.
Utilizing the photometric data and the CIGALE code for stellar
population and dust emission fitting, we derived the stellar masses,
stellar population ages, and stellar metallicities for these detached
TDGs.
Compared to standard mass-metallicity relations for dwarf galaxies,
five of the seven candidates have higher than expected metallicities,
confirming their tidal origins. One of the seven candidates remains
unclear due to large uncertainties in metallicity, and another has
stellar and nebular metallicities compatible with those of a
preexisting dwarf galaxy. The latter object is relatively compact in
the optical relative to its stellar mass, in contrast to the other
candidate TDGs, which have large diameters for their stellar masses
compared to most dwarf galaxies. The derived stellar population ages
range from 100 Myr to 900 Myr, while the inferred stellar masses are
between 2x106M☉ and 8x107M☉.
Four of the six TDGs are associated with the gas-rich M51-like pair
Arp 72, one TDG is associated with a second M51-like pair Arp 86, and
another is associated with Arp 65, an approximately equal mass pair.
In spite of the relatively low stellar masses of these TDGs, they have
survived for at least 100-900Myrs, suggesting that they are stable
and in dynamical equilibrium. We conclude that encounters with a
relatively low-mass companion (1/10th-1/4th of the mass of the
primary) can also produce long-lasting TDGs.
Description:
Most of the SB&T systems have been observed in the IR at 3.6, 4.5,
5.8, 8.0, and 24um by the Spitzer telescope, and in the far-UV (FUV)
and near-UV (NUV) filters by the Galaxy Evolution Explorer (GALEX)
satellite. In the current study, we only used GALEX images with
exposure times greater than 1000 seconds. Many of the SB&T galaxies
also have Sloan Digitized Sky Survey (SDSS) optical ugriz images
available (Smith et al., 2010AJ....139.1212S 2010AJ....139.1212S, Cat J/AJ/139/1212,
2016AJ....151...63S 2016AJ....151...63S). For systems without SDSS images, we use Dark
Energy Spectroscopic Instrument Legacy Imaging Surveys (DESI-LIS) grz
images when available (Dey et al., 2019AJ....157..168D 2019AJ....157..168D). About half of
the SB&T galaxies have narrowband Hα maps available (Smith et
al., 2016AJ....151...63S 2016AJ....151...63S). About one third have been mapped in the
21cm HI line. We also used Two Micron All-Sky Survey (2MASS) J, H, and
K images1 to obtain near-IR photometry of our candidate TDGs.
Based on the above selection criteria, including the presence of
Hα and/or HI, we conducted an observational campaign to obtain
optical spectra of the most promising TDG candidates. A total of 11
candidate detached TDG were observed; of these, six were found to have
redshifts that matched the target galaxy pair, while five were found
to have redshifts that did not match the target galaxy pair.
The observations were carried out using the Boller & Chivens
spectrograph mounted on the 2.1m telescope at the San Pedro Martir
Observatory. We utilized the 600l/mm grating with a slit width of
3arcsec, providing a spectral resolution of approximately ∼4Å over
a range spanning from 4800 to 7100Å. A summary of the observations
is presented in Table 1. During each night of observations, a
spectrophotometric standard star was observed to enable flux
calibration of the 1D spectrum. The standard longslit spectral
reduction techniques were applied to the data, including cosmic ray
removal, bias subtraction, flat field correction, combination of
multiple exposures, wavelength calibration, 1D spectra extraction, and
sky subtraction. IRAF was used for these tasks.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 72 11 Observing log, and derived redshift
table2.dat 118 8 Extinction corrected emission line fluxes
table3.dat 214 7 GALEX, Spitzer, and DESI-LIS Photometry
table5.dat 76 7 Output results from CIGALE fits
list.dat 120 6 List of fits spectra
fits/* . 6 Individual fits spectra
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 - ID Galaxy identifier
9- 19 F11.7 deg RAdeg Right Ascension (J2000)
21- 31 F11.7 deg DEdeg Declination (J2000)
33- 42 A10 "date" Date Date of observation
44- 45 I2 min Texp Exposure time
47 I1 --- Nobs Number of times observed
49- 52 I4 0.1nm SpRange1 Spectral Range of the observation
53 A1 --- --- [-]
54- 57 I4 0.1nm SpRange2 Spectral Range of the observation
59- 65 F7.5 --- z Measured Redshift
67- 72 F6.4 --- e_z Measured Redshift uncertainty
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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- 7 A7 --- ID Galaxy identifier
9- 14 F6.1 10-20W/m2 FHa Halpha flux
16- 18 F3.1 10-20W/m2 e_FHa Halpha flux uncertainty
20- 24 F5.1 10-20W/m2 FHb Hbeta flux
26- 28 F3.1 10-20W/m2 e_FHb Hbeta flux uncertainty
30- 35 F6.2 10-20W/m2 F[OIII]4959 ? [OIII]4959 flux
37- 40 F4.2 10-20W/m2 e_F[OIII]4959 ? [OIII]4959 flux uncertainty
42- 48 F7.2 10-20W/m2 F[OIII]5007 ? [OIII]5007 flux
50- 53 F4.2 10-20W/m2 e_F[OIII]5007 ? [OIII]5007 flux uncertainty
55- 58 F4.1 10-20W/m2 F[NII]6548 ? [NII]6548 flux
60- 62 F3.1 10-20W/m2 e_F[NII]6548 ? [NII]6548 flux uncertainty
64- 68 F5.1 10-20W/m2 F[NII]6583 ? [NII]6583 flux
70- 72 F3.1 10-20W/m2 e_F[NII]6583 ? [NII]6583 flux uncertainty
74- 79 F6.2 10-20W/m2 F[SII]6717 ? [SII]6717 flux
81- 84 F4.2 10-20W/m2 e_F[SII]6717 ? [SII]6717 flux uncertainty
86- 91 F6.2 10-20W/m2 F[SII]6731 ? [SII]6731 flux
93- 96 F4.2 10-20W/m2 e_F[SII]6731 ? [SII]6731 flux uncertainty
98-102 F5.3 mag E(B-V) ? Color excess
104-108 F5.3 mag e_E(B-V) ? Color excess uncertainty
110-113 F4.2 --- 12+log(O/H) ? Oxygen nebular abundance
115-118 F4.2 --- e_12+log(O/H) ? Oxygen nebular abundance uncertainty
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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- 6 A6 --- ID Galaxy identifier
8- 14 F7.5 mJy FFUV FUV Flux from GALEX
16- 22 F7.5 mJy e_FFUV FUV Flux from GALEX uncertainty
24- 30 F7.5 mJy FNUV NUV Flux from GALEX
32- 38 F7.5 mJy e_FNUV NUV Flux from GALEX uncertainty
40 A1 --- l_FuSDSS Limit flag on FuSDSS
41- 45 F5.3 mJy FuSDSS u Flux from SDSS
47- 51 F5.3 mJy e_FuSDSS ? u Flux from SDSS uncertainty
53- 58 F6.4 mJy FgSDSS g Flux from SDSS
60- 65 F6.4 mJy e_FgSDSS g Flux from SDSS uncertainty
67 A1 --- l_FrSDSS Limit flag on FrSDSS
68- 73 F6.4 mJy FrSDSS r Flux from SDSS
75- 80 F6.4 mJy e_FrSDSS ? r Flux from SDSS uncertainty
82 A1 --- l_FiSDSS Limit flag on FiSDSS
83- 87 F5.3 mJy FiSDSS i Flux from SDSS
89- 93 F5.3 mJy e_FiSDSS ? i Flux from SDSS uncertainty
95 A1 --- l_FzSDSS Limit flag on FzSDSS
96-100 F5.3 mJy FzSDSS z Flux from SDSS
102-106 F5.3 mJy e_FzSDSS ? z Flux from SDSS uncertainty
108-113 F6.4 mJy FgDES g Flux from DESI Legacy Imaging Survey
115-120 F6.4 mJy e_FgDES g Flux from DESI Legacy Imaging Survey
uncertainty
122-127 F6.4 mJy FrDES r Flux from DESI Legacy Imaging Survey
129-134 F6.4 mJy e_FrDES r Flux from DESI Legacy Imaging Survey
uncertainty
136 A1 --- l_FzDES Limit flag on FzDES
137-142 F6.4 mJy FzDES z Flux from DESI Legacy Imaging Survey
144-149 F6.4 mJy e_FzDES ? z Flux from DESI Legacy Imaging Survey
uncertainty
151-156 F6.4 mJy F3.6um ? 3.6 microns Flux from Spitzer
158-163 F6.4 mJy e_F3.6um ? 3.6 microns Flux from Spitzer uncertainty
165 A1 --- l_F4.5um Limit flag on F4.5um
166-171 F6.4 mJy F4.5um ? 4.5 microns Flux from Spitzer
173-178 F6.4 mJy e_F4.5um ? 4.5 microns Flux from Spitzer uncertainty
180 A1 --- l_F5.8um Limit flag on F5.8um
181-185 F5.3 mJy F5.8um ? 5.8 microns Flux from Spitzer
187-192 F6.4 mJy e_F5.8um ? 5.8 microns Flux from Spitzer uncertainty
193-197 F5.3 mJy F8um ? 8 microns Flux from Spitzer
199-204 F6.4 mJy e_F8um ? 8 microns Flux from Spitzer uncertainty
205 A1 -- l_F24um Limit flag on F24um
206-209 F4.2 mJy F24um ? 24 microns Flux from Spitzer
211-214 F4.2 mJy e_F24um ? 24 microns Flux from Spitzer uncertainty
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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- 6 A6 - ID Galaxy identifier
8- 14 E7.3 Msun M* Stellar Mass
16- 22 E7.3 Msun e_M* Stellar Mass uncertainty
24- 29 F6.4 - Z Stellar metallicity
31- 36 F6.4 - e_Z Stellar metallicity uncertainty
38- 43 F6.4 Msun/yr SFR Star Formation Rate
45- 50 F6.4 Msun/yr e_SFR Star Formation Rate uncertainty
52- 55 F4.2 - fBurst Fraction of stars formed in the recent burst
relative to the total mass of stars ever
formed
57- 60 F4.2 - e_fBurst Fraction of stars formed in the recent burst
relative to the total mass of stars ever
formed uncertainty
62- 68 E7.3 Myr BurstAge Age of the recent burst
70- 76 E7.3 Myr e_BurstAge Age of the recent burst uncertainty
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 34 A10 "datime" Obs.date Observation date
36- 42 F7.2 0.1nm blambda Lower value of wavelength interval
44- 50 F7.2 0.1nm Blambda Upper value of wavelength interval
52- 58 F7.5 0.1nm dlambda Wavelength resolution
60- 61 I2 Kibyte size Size of FITS file
63-104 A42 --- FileName Name of FITS file, in subdirectory fits
106-120 A15 --- Title Title of the FITS file
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Acknowledgements:
Javier Zaragoza-Cardiel, jzaragoza(at)cefca.es
(End) Patricia Vannier [CDS] 27-Jun-2024