Environmental processing in cluster core galaxies at <i>z</i> = 1.7

Castignani, G.; Combes, F.; Salomé, P.

doi:10.1051/0004-6361/201937155

Cited by 21 publications

(24 citation statements)

References 73 publications

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“…A large reservoir (∼ 10 11 M ) of molecular gas was detected, likely associated with a number of cluster core BCG companions, unresolved by the LMT, within the large 25 arcsec diameter (i.e., ∼ 200 kpc at z = 1.7). Our recent NOEMA observations (Castignani et al 2020b) confirmed this scenario, with the detection of two gas-rich BCG companions within 20 kpc from the BCG, and allowed us to set a robust upper limit to the molecular gas reservoir M H 2 < 1.1 × 10 10 M .…”

Section: Distant Bcgs Observed In Cosupporting

confidence: 61%

Molecular gas in distant brightest cluster galaxies

Castignani

Combes

Salomé

et al. 2020

A&A

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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 100 M /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, M H 2 = (8.7 ± 1.1) × 10 10 M , and a high level of excitation r 31 = 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 r e = (11.6 ± 0.3) kpc, similarly to those found independently both in ultraviolet and in H α in previous work. We tentatively detected CO(1→0) or CO(2→1) in four other BCGs, with molecular gas reservoirs in the range M H 2 = 2 × 10 10−11 M . For the remaining 13 BCGs we set robust upper limits of M H 2 /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 (M H 2 /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 M H 2 10 10 M 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.

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Section: Distant Bcgs Observed In Cosupporting

confidence: 61%

Molecular gas in distant brightest cluster galaxies

Castignani

Combes

Salomé

et al. 2020

A&A

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“…Such features may have suggested that the intense starbursting occurring in SpARCS1049 is being driven by a merger-like event, but an extremely large molecular gas reservoir of 1.1±0.1×10 11 M e was also detected in the core (Webb et al 2017) and showed no signs of multiple velocity peaks as would be expected in a major merger event (Gao et al 2001;Greve et al 2005;Schulz et al 2007). Recently, these features were also interpreted as evidence of ram pressure stripping occurring in the cluster core (Castignani et al 2020).…”

Section: Ir 12mentioning

confidence: 85%

“…Recently, Castignani et al (2020) obtained NOEMA CO(  4 3) and continuum map observations of SpARCS1049. They detected two sources within 20 kpc of the BCG: the first appeared to be associated with a pair of merging cluster galaxies, while the second showed evidence of a CO(  4 3) tail and was interpreted as evidence for ram pressure stripping.…”

Section: Runaway Gas Cooling As the Source Of The Starburstmentioning

confidence: 99%

Evidence of Runaway Gas Cooling in the Absence of Supermassive Black Hole Feedback at the Epoch of Cluster Formation

Hlavacek-Larrondo

Rhea

Webb

et al. 2020

ApJL

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Cosmological simulations, as well as mounting evidence from observations, have shown that supermassive black holes play a fundamental role in regulating the formation of stars throughout cosmic time. This has been clearly demonstrated in the case of galaxy clusters in which powerful feedback from the central black hole is preventing the hot intracluster gas from cooling catastrophically, thus reducing the expected star formation rates by orders of magnitude. These conclusions, however, have been almost entirely based on nearby clusters. Based on new Chandra X-ray observations, we present the first observational evidence for massive, runaway cooling occurring in the absence of supermassive black hole feedback in the high-redshift galaxy cluster SpARCS104922.6+564032.5 (z=1.709). The hot intracluster gas appears to be fueling a massive burst of star formation (≈900 M e yr −1) that is offset by dozens of kpc from the central galaxy. The burst is co-spatial with the coolest intracluster gas but not associated with any galaxy in the cluster. In less than 100 million years, such runaway cooling can form the same amount of stars as in the Milky Way. Therefore, intracluster stars are not only produced by tidal stripping and the disruption of cluster galaxies, but can also be produced by runaway cooling of hot intracluster gas at early times. Overall, these observations show the dramatic impact when supermassive black hole feedback fails to operate in clusters. They indicate that in the highest overdensities, such as clusters and protoclusters, runaway cooling may be a new and important mechanism for fueling massive bursts of star formation in the early universe. Unified Astronomy Thesaurus concepts: High-redshift galaxy clusters (2007); Supermassive black holes (1663); Cooling flows (2028); Intracluster medium (858); X-ray observatories (1819)

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“…This gas component is one of the most massive reported so far for an HzRG nucleus in an overdense region. Other examples of large gas reservoirs detected around similar objects are the Spiderweb (∼2 × 10 10 (α CO /0.8) M at z = 2.2; Emonts et al 2018), SpARCS J1049+56 (M H 2 ∼ 1 × 10 11 (α CO /0.8) M at z = 1.7; Webb et al 2017; see also Castignani et al 2020), and Candels-5001 (M H 2 ∼ 2−6 × 10 11 (α CO /10) M at z = 3.47; Ginolfi et al 2017) BCGs.…”

Section: Frii Host Galaxymentioning

confidence: 96%

Discovery of molecular gas fueling galaxy growth in a protocluster at z = 1.7

D’Amato

Gilli²,

Prandoni

et al. 2020

A&A

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Based on ALMA Band 3 observations of the CO(2→1) line transition, we report the discovery of three new gas-rich (MH2 ∼ 1.5 − 4.8 × 1010 M⊙) galaxies in an overdense region at z = 1.7 that already contains eight spectroscopically confirmed members. This leads to a total of 11 confirmed overdensity members within a projected distance of ∼1.15 Mpc and in a redshift range of Δz = 0.012. Under simple assumptions, we estimate that the system has a total mass of ≥3 − 6 × 1013 M⊙, and show that it will likely evolve into a ≳1014 M⊙ cluster at z = 0. The overdensity includes a powerful Compton-thick Fanaroff-Riley type II (FRII) radio galaxy, around which we discovered a large molecular gas reservoir (MH2 ∼ 2 × 1011 M⊙). We fit the FRII resolved CO emission with a 2D Gaussian model with a major (minor) axis of ∼27 (∼17) kpc, which is a factor of ∼3 larger than the optical rest-frame emission. Under the assumption of a simple edge-on disk morphology, we find that the galaxy interstellar medium produces a column density toward the nucleus of ∼5.5 × 1023 cm−2. A dense interstellar medium like this may then contribute significantly to the total nuclear obscuration measured in the X-rays (NH, X ∼ 1.5 × 1024 cm−2) in addition to a small, paresec-scale absorber around the central engine. The velocity map of this source unveils a rotational motion of the gas that is perpendicular to the radio jets. All ALMA sources have a dust-reddened counterpart in deep Hubble Space Telescope images (bands i, z, H), while we do not detect any molecular gas reservoir around the known UV-bright, star-forming members discovered by MUSE. This highlights the capability of ALMA of tracing gas-rich members of the overdensity. For the MUSE sources, we derive 3σ upper limits to the molecular gas mass of MH2 ≤ 2.8 − 4.8 × 1010 M⊙. We derive star formation rates in the range ∼5 − 100 M⊙ yr−1 for the three new ALMA sources. The FRII is located at the center of the projected spatial distribution of the structure members, and its velocity offset from the peak of the redshift distribution is well within the velocity dispersion of the structure. All this, coupled with the large amount of gas around the FRII, its stellar mass of ∼3 × 1011 M⊙, star formation rate of ∼200 − 600 M⊙ yr−1, and powerful radio-to-X-ray emission, suggests that this source is the likely progenitor of the future brightest cluster galaxy.

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Environmental processing in cluster core galaxies at z = 1.7

Cited by 21 publications

References 73 publications

Molecular gas in distant brightest cluster galaxies

Molecular gas in distant brightest cluster galaxies

Evidence of Runaway Gas Cooling in the Absence of Supermassive Black Hole Feedback at the Epoch of Cluster Formation

Discovery of molecular gas fueling galaxy growth in a protocluster at z = 1.7

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