J/A+A/640/A65 CLASH brightest cluster galaxies CO spectra (Castignani+, 2020)
Molecular gas in CLASH brightest cluster galaxies at z∼0.2-0.9.
Castignani G., Pandey-Pommier M., Hamer S.L., Combes F., Salome P.,
Freundlich J., Jablonka P.
<Astron. Astrophys. 640, A65 (2020)>
=2020A&A...640A..65C 2020A&A...640A..65C (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Spectra, radio ; Carbon monoxide
Keywords: galaxies: clusters: general - galaxies: star formation -
galaxies: evolution - galaxies: active - molecular data.
Abstract:
Brightest cluster galaxies (BCGs) are excellent laboratories to study
galaxy evolution in dense Mpc-scale environments. We have observed in
CO(1->0), CO(2->1), CO(3->2), or CO(4->3), with the IRAM-30m, 18 BCGs
at z∼0.2-0.9 that are drawn from the Cluster Lensing And Supernova
survey with Hubble (CLASH) survey. Our sample includes RX1532, which
is our primary target, being among the BCGs with the highest star
formation rate (SFR≳100M☉/yr) in the CLASH sample. We
unambiguously detected both CO(1->0) and CO(3->2) in RX1532, yielding
a large reservoir of molecular gas, MH2=(8.7±1.1)1010M☉,
and a high level of excitation r31=0.75±0.12. A morphological
analysis of the Hubble Space Telescope I-band image of RX1532 reveals
the presence of clumpy substructures both within and outside the
half-light radius re=(11.6±0.3)kpc, similarly to those found
independently both in ultraviolet and in H in previous work. We
tentatively detected CO(1->0) or CO(2->1) in four other BCGs, with
molecular gas reservoirs in the range MH2=2x1010-11M☉. For
the remaining 13 BCGs we set robust upper limits of MH2/M*≲0.1,
which are among the lowest molecular gas to stellar mass ratios found
for distant ellipticals and BCGs. By comparison with distant cluster
galaxies observed in CO our study shows that RX1532
(MH2/M*=0.40±0.05) belongs to the rare population of star forming
and gas-rich BCGs in the distant universe. By using available X-ray
based estimates of the central intra-cluster medium entropy, we show
that the detection of large reservoirs of molecular gas
MH2≳1010M☉ in distant BCGs is possible when the two
conditions are met: i) high SFR and ii) low central entropy, which
favors the condensation and the inflow of gas onto the BCGs
themselves, similarly to what has been previously found for some local
BCGs.
Description:
Each file corresponds to the reduced 30m spectrum for a given BCG and
a CO line, as indicated by the file name. In each file, the first
column is relative velocity (km/s), the second column is Tmb (mK)
The reduced spectra are reported in Figs 3 and A.1 of the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 104 7 Summary of our IRAM 30m results for the sources
with secure or tentative CO detections
sp/* . 7 Individual spectra
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Galaxy Galaxy name
8- 9 I2 h RAh Right ascension (J2000)
11- 12 I2 min RAm Right ascension (J2000)
14- 18 F5.2 s RAs Right ascension (J2000)
20 A1 --- DE- Declination sign (J2000)
21- 22 I2 deg DEd Declination (J2000)
24- 25 I2 arcmin DEm Declination (J2000)
27- 30 F4.1 arcsec DEs Declination (J2000)
32- 36 F5.3 --- zsp Spectroscopic redshift
38- 41 A4 --- CO CO (J->J-1)
43- 46 F4.1 Jy.km/s SCO CO (J->J-1) integrated intensity
48- 50 F3.1 Jy.km/s e_SCO CO (J->J-1) integrated intensity error
52- 55 F4.1 --- S/N Signal-to-noise ratio
57- 59 I3 km/s FWHM FWHM
61- 63 I3 km/s e_FWHM FWHM error
65- 68 F4.1 10+9K.km/s/pc2 L'CO CO (J->J-1) luminosity
70- 73 F4.1 10+9K.km/s/pc2 e_L'CO CO (J->J-1) luminosity error
74 A1 --- n_L'CO [+] Note on L'CO (1)
76- 81 F6.4 --- z CO (J->J-1) redshift
83- 88 F6.4 --- e_z CO (J->J-1) redshift error
90-104 A15 ---- FileName Name of the spectrum file in
subdirectory sp
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Note (1): +: The reported L'CO(2->1) of M2129 is estimated from the CO(2->1)
flux and has been increased by a factor of two to take into account the
possibility that the fit misses a substantial part of the CO(2->1) emission.
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Byte-by-byte Description of file: sp/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
3- 10 F8.2 km/s RVel Relative velocity
13- 20 F8.5 mK Tmb Mean brigthness temperature
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Acknowledgements:
Gianluca Castignani, gianluca.castignani(at)epfl.ch
(End) Patricia Vannier [CDS] 04-Jun-2020