J/A+A/635/A32 Molecular gas in distant brightest cluster gal. (Castignani+ 2020)
Molecular gas in distant brightest cluster galaxies.
Castignani G., Combes F., Salome P., Freundlich J.
<Astron. Astrophys., 635, A32 (2020)>
=2020A&A...635A..32C 2020A&A...635A..32C (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Carbon monoxide
Keywords: galaxies: clusters: general - galaxies: star formation -
galaxies: evolution - galaxies: active - molecular data
Abstract:
The mechanisms governing the stellar mass assembly and star formation
history of brightest cluster galaxies (BCGs) are still being debated.
By means of new and archival molecular gas observations we investigate
the role of dense megaparsec-scale environments in regulating the
fueling of star formation in distant BCGs, through cosmic time. We
observed in CO with the IRAM 30m telescope two star-forming BCGs
belonging to SpARCS clusters, namely, 3C 244.1 (z=0.4) and SDSS
J161112.65+550823.5 (z=0.9), and compared their molecular gas and star
formation properties with those of a compilation of ∼100 distant
cluster galaxies from the literature, including nine additional
distant BCGs at z∼0.4-3.5. We set robust upper limits of
MH2<1.0x1010M☉ and <2.8x1010M☉ to their molecular
gas content, respectively, and to the ratio of molecular gas to
stellar mass M(H2)/M*≤0.2 and depletion time τdep≤40Myr of
the two targeted BCGs. They are thus among the distant cluster
galaxies with the lowest gas fractions and shortest depletion times.
The majority (64%±15% and 73%±18%) of the 11 BCGs with
observations in CO have lower M(H2)/M* values and τdep,
respectively, than those estimated for main sequence galaxies.
Statistical analysis also tentatively suggests that the values of
M(H2)/M* and τdep for the 11 BCGs deviates, with a
significance of ∼2σ, from those of the comparison sample of
cluster galaxies. A morphological analysis for a subsample of seven
BCGs with archival HST observations reveals that 71%±17% of the BCGs
are compact or show star-forming components or substructures. Our
results suggest a scenario where distant star-forming BCGs assemble a
significant fraction ∼16% of their stellar mass on the relatively
short timescale ~τdep, while environmental mechanisms might
prevent the replenishment of gas feeding the star formation. We
speculate that compact components also favor the rapid exhaustion of
molecular gas and ultimately help to quench the BCGs. Distant
star-forming BCGs are excellent targets for ALMA and for
next-generation telescopes such as the James Webb Space Telescope.
Description:
We present a compilation of distant cluster galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 156 109 Properties of distant z≳0.2 cluster galaxies
observed in CO
tablea2.dat 156 11 Properties of distant BCG (candidates)
observed in CO
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Byte-by-byte Description of file: tablea1.dat tablea2.dat
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Bytes Format Units Label Explanations
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1- 24 A24 --- Cluster (Proto-)cluster name
26- 30 F5.3 --- zCl (Proto-)cluster redshift
32- 33 I2 --- Ref Reference for (Proto-)cluster (1)
35- 58 A24 --- Galaxy Galaxy name
60- 64 F5.3 --- z Galaxy redshift
66- 70 A5 --- Trans Transition
72- 80 A9 --- Tel Telescope
82- 85 F4.2 --- rJ1 Excitation ratio
87- 91 F5.2 Msun/K.(km/s).pc2 alphaCO ?=- Galaxtic CO-to-H2 conversion
factor (in Msun/(K.(km/s).pc2)
92 A1 --- --- [,]
93- 96 F4.2 Msun/K.(km/s).pc2 alphaCO2 ? Second Galaxtic CO-to-H2
conversion factor
(in Msun/(K.(km/s).pc2)
98 A1 --- l_L'CO(1-0) Limit flag on L'CO(1-0)
99-103 F5.2 10+10K.(km/s).pc2 L'CO(1-0) Luminosity in CO(1-0) line,
in 1010K.(km/s).pc2
105-108 F4.2 10+10K.(km/s).pc2 E_L'CO(1-0) ? Error on L'CO(1-0) (upper value)
110-113 F4.2 10+10K.(km/s).pc2 e_L'CO(1-0) ? Error on L'CO(1-0) (lower value)
116-120 F5.1 10+10Msun M* Stellar mass
122-126 F5.2 10+10Msun E_M* ? Error on M* (upper value)
127-130 F4.1 10+10Msun e_M* ? Error on M* (lower value)
132 A1 --- l_SFR Limit flag on SFR
133-138 F6.1 Msun/yr SFR Star formation rate
139-144 F6.1 Msun/yr E_SFR ? Error on SFR (upper value)
146-150 F5.1 Msun/yr e_SFR ? Error on SFR (lower value)
152-156 F5.1 Msun/yr SFRMS Star formation rate for
main sequence
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Note (1): References as follows:
1 = Cybulski et al. (2016MNRAS.459.3287C 2016MNRAS.459.3287C)
Cybulski et al. (2016MNRAS.459.3287C 2016MNRAS.459.3287C) report infrared luminosities for
their z∼0.2 cluster galaxies, which we have converted into SFR estimates
using the Kennicutt (1998ARA&A..36..189K 1998ARA&A..36..189K) relation.
2 = Geach et al. (2011ApJ...730L..19G 2011ApJ...730L..19G)
3 = Jablonka et al. (2013A&A...557A.103J 2013A&A...557A.103J)
Jablonka et al. (2013A&A...557A.103J 2013A&A...557A.103J) did not assume any value of
αCO; these sources are flagged with '---' in the
αCO column.
4 = Wagg et al. (2012ApJ...752...91W 2012ApJ...752...91W)
5 = Castignani et al. (2018A&A...617A.103C 2018A&A...617A.103C)
In our previous work Castignani et al. (2018A&A...617A.103C 2018A&A...617A.103C) we detected
in CO(2-->1) two unresolved cluster galaxies, with the same redshift and
M* (Zeimann et al., 2013ApJ...779..137Z 2013ApJ...779..137Z, Cat. J/ApJ/779/137), that we
show in the table. Consistently with Castignani et al.
(2018A&A...617A.103C 2018A&A...617A.103C) we also report L'CO(1-->0) and the SFR derived
from the 24µm observer frame flux, for each of two galaxies, assuming
that they equally contribute to the observed (unresolved) emission.
6 = Hayashi et al. (2018ApJ...856..118H 2018ApJ...856..118H)
Consistently with the order of preference adopted by Hayashi et al.
(2018ApJ...856..118H 2018ApJ...856..118H), we report the SFR estimated using both UV and
24µm observer frame emission, when available (i.e., for the sources
with ID ALMA.01, 06, 08, 10, 12, 13, and 15). We report the SFR estimated
from the mid-IR to optical SED for the remaining galaxies with
ID: ALMA.02, 03, 04, 05, 07, 09, 11, 14, 16, and 17).
7 = Kneissl et al. (2019A&A...625A..96K 2019A&A...625A..96K)
Kneissl et al. (2019A&A...625A..96K 2019A&A...625A..96K) report gas masses assuming two
separate values of αCO, which are listed in this Table.
8 = Aravena et al. (2012MNRAS.426..258A 2012MNRAS.426..258A)
For the Aravena et al. (2012MNRAS.426..258A 2012MNRAS.426..258A) sources the reported SFRs
are the average between those derived from infrared luminosity and
from SED fitting.
9 = Noble et al. (2017ApJ...842L..21N 2017ApJ...842L..21N)
10 = Rudnick et al. (2017ApJ...849...27R 2017ApJ...849...27R)
11 = Noble et al. (2019ApJ...870...56N 2019ApJ...870...56N)
12 = Coogan et al. (2018MNRAS.479..703C 2018MNRAS.479..703C)
For the Coogan et al. (2018MNRAS.479..703C 2018MNRAS.479..703C) Cl J1449+0856 galaxies with
M* estimates, reported in this table, we list the SFRs derived from the
870µm observer frame flux. In the cases where the sources are not
detected in CO(1-->0), we have used the CO(4-->3) detections to estimate
L'CO(1-->0), by assuming an excitation ratio r41=0.36, equal to
the mean between the ratios of the two sources (ID 6, B1) with both
CO(1-->0) and CO(4-->3) detections. Coogan et al. (2018MNRAS.479..703C 2018MNRAS.479..703C)
did not report any value of αCO for their source S7; this source
is flagged with '---' in the αCO column.
13 = Tadaki et al. (2019PASJ...71...40T 2019PASJ...71...40T)
14 = Gomez-Guijarro et al. (2019ApJ...872..117G 2019ApJ...872..117G)
15 = Ivison et al. (2013ApJ...772..137I 2013ApJ...772..137I)
16 = Lee et al. (2017ApJ...842...55L 2017ApJ...842...55L)
17 = Wang et al. (2018ApJ...867L..29W 2018ApJ...867L..29W)
Wang et al. (2018ApJ...867L..29W 2018ApJ...867L..29W) report infrared luminosities for their
z∼2.5 cluster galaxies, which we have converted into SFR estimates using
the Kennicutt (1998ARA&A..36..189K 1998ARA&A..36..189K) relation.
18 = Bolatto et al. (2013ARA&A..51..207B 2013ARA&A..51..207B) and
Umehata et al. (2015ApJ...815L...8U 2015ApJ...815L...8U)
19 = Carilli et al. (2010ApJ...714.1407C 2010ApJ...714.1407C) and Tan et al. (2014A&A...569A..98T 2014A&A...569A..98T)
20 = Walter et al. (2012Natur.486..233W 2012Natur.486..233W) and
Serjeant & Marchetti (2014MNRAS.443.3118S 2014MNRAS.443.3118S)
21 = Riechers et al. (2010ApJ...720L.131R 2010ApJ...720L.131R)
22 = Webb et al. (2015ApJ...809..173W 2015ApJ...809..173W), Webb et al. (2017ApJ...844L..17W 2017ApJ...844L..17W)
23 = Gobat et al. (2011A&A...526A.133G 2011A&A...526A.133G), Coogan et al. (2018MNRAS.479..703C 2018MNRAS.479..703C)
For the Cl J1449+0856 BCG the reported SFR is derived from the 870µm
observer frame flux (Coogan et al., 2018MNRAS.479..703C 2018MNRAS.479..703C); to estimate
L'CO(1-->0), an excitation ratio r41=0.36 is assumed, equal to the
mean between the ratios of the two Coogan et al. (2018MNRAS.479..703C 2018MNRAS.479..703C)
sources (ID 6, B1) with both CO(1-->0) and CO(4-->3) detections. The
reported values for αCO and L'CO(1-->0) imply a molecular gas
mass ∼1010.8 M☉, while Coogan et al. (2018MNRAS.479..703C 2018MNRAS.479..703C) find
a dynamical mass equal to 1010.3±0.3 M☉. The two estimates are
fairly consistent with each other within the uncertainties.
24 = Emonts et al. (2013MNRAS.430.3465E 2013MNRAS.430.3465E), Emonts et al. (2016Sci...354.1128E 2016Sci...354.1128E),
Hatch et al. (2008MNRAS.383..931H 2008MNRAS.383..931H), Hatch et al. (2009MNRAS.395..114H 2009MNRAS.395..114H)
For MRC 1138-262 we report the SFR=142M☉/yr (Emonts et al.,
2016Sci...354.1128E 2016Sci...354.1128E), with uncertainties derived assuming maximum and
minimum values equal to SFR=1400M☉/yr (Emonts et al.,
2013MNRAS.430.3465E 2013MNRAS.430.3465E) and SFR=57 M☉/yr (Hatch et al.,
2008MNRAS.383..931H 2008MNRAS.383..931H), respectively.
25 = Ginolfi et al. (2017MNRAS.468.3468G 2017MNRAS.468.3468G)
26 = Castignani et al. (2019A&A...623A..48C 2019A&A...623A..48C)
27 = This work
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Acknowledgements:
Gianluca Castignani, gianluca.castignani(at)unibo.it
(End) Patricia Vannier [CDS] 25-Apr-2022