HST GRISM CONFIRMATION OF TWO z ∼ 2 STRUCTURES FROM THE CLUSTERS AROUND RADIO-LOUD AGN (CARLA) SURVEY

Noirot, Gaël; Vernet, J.; Breuck, C. De; Wylezalek, Dominika; Galametz, A.; Stern, Daniel; Mei, S.; Brodwin, M.; Cooke, Elizabeth A.; Gonzalez, Anthony H.; Hatch, N. A.; Rettura, Alessandro; Stanford, S. A.

doi:10.3847/0004-637x/830/2/90

Cited by 35 publications

(40 citation statements)

References 97 publications

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“…Thus, relative low speed encounters are favored for efficient merging. In the over-densities surrounding the high redshift radio galaxies, the dispersion of the most massive galaxies in the potential appears to be high (Kuiper et al 2011;Noirot et al 2018).…”

Section: Growth Through Major Mergersmentioning

confidence: 99%

Massive galaxies on the road to quenching: ALMA observations of powerful high redshift radio galaxies

Falkendal

Breuck

Lehnert

et al. 2019

A&A

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We present 0 . 3 (band 6) and 1 . 5 (band 3) ALMA observations of the (sub)millimeter dust continuum emission for 25 radio galaxies at 1 < z < 5.2. Our survey reaches a rms flux density of ∼50 µJy in band 6 (200-250 GHz) and ∼20 µJy in band 3 (100-130 GHz). This is an order of magnitude deeper than single-dish 850 µm observations, and reaches fluxes where synchrotron and thermal dust emission are expected to be of the same order of magnitude. Combining our sensitive ALMA observations with low-resolution radio data from ATCA, higher resolution VLA data, and infrared photometry from Herschel and Spitzer, we have disentangled the synchrotron and thermal dust emission. We determine the star-formation rates and AGN infrared luminosities using our newly developed Multiresolution and multi-object/origin spectral energy distribution fitting code (Mr-Moose). We find that synchrotron emission contributes substantially at λ ∼1 mm. Through our sensitive flux limits and accounting for a contribution from synchrotron emission in the mm, we revise downward the median star-formation rate by a factor of seven compared to previous estimates based solely on Herschel and Spitzer data. The hosts of these radio-loud AGN appear predominantly below the main sequence of star-forming galaxies, indicating that the star formation in many of the host galaxies has been quenched. Future growth of the host galaxies without substantial black hole mass growth will be needed to bring these objects on the local relation between the supermassive black holes and their host galaxies. Given the mismatch in the timescales of any star formation that took place in the host galaxies and lifetime of the AGN, we hypothesize that a key role is played by star formation in depleting the gas before the action of the powerful radio jets quickly drives out the remaining gas. This positive feedback loop of efficient star formation rapidly consuming the gas coupled to the action of the radio jets in removing the residual gas is how massive galaxies are rapidly quenched.

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Section: Growth Through Major Mergersmentioning

confidence: 99%

Massive galaxies on the road to quenching: ALMA observations of powerful high redshift radio galaxies

Falkendal

Breuck

Lehnert

et al. 2019

A&A

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“…To the best of our knowledge this proto-cluster candidate has never been reported in previous work. If confirmed spectroscopically, it will be one of the most distant proto-clusters discovered around radio galaxies (see also e.g., Noirot et al 2016Noirot et al , 2018. Castignani et al (2014a) searched for overdensities associated with z > 1 COSMOS-FRI radio galaxies within the proto-cluster catalog of Diener et al (2013), which was constructed using spectroscopic redshift information from the zCOSMOS-deep survey (Lilly et al 2007, Lilly et al, in prep.).…”

Section: Low-richness Structuresmentioning

confidence: 99%

“…In fact redsequence modeling of distant (proto-)cluster galaxies might lead to results of which interpretation is difficult, even with the use of spectroscopic redshifts. We refer for example to Kotyla et al (2016) and Noirot et al (2016) who derived CM plots for galaxies around distant radio-loud AGNs in dense megaparsec-scale environments.…”

Section: Star Forming (Proto-)bcg Candidatesmentioning

confidence: 99%

Molecular gas in radio galaxies in dense megaparsec-scale environments at z = 0.4–2.6

Castignani

Combes

Salomé

et al. 2019

A&A

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Context. Low luminosity radio galaxies (LLRGs) typically reside in dense megaparsec-scale environments and are often associated with brightest cluster galaxies (BCGs). They are an excellent tool to study the evolution of molecular gas reservoirs in giant ellipticals, even close to the active galactic nucleus. Aims. We investigate the role of dense megaparsec-scale environment in processing molecular gas in LLRGs in the cores of galaxy (proto-)clusters. To this aim we selected within the COSMOS and DES surveys a sample of five LLRGs at z = 0.4 − 2.6 that show evidence of ongoing star formation on the basis of their far-infrared (FIR) emission. Methods. We assembled and modeled the FIR-to-UV spectral energy distributions (SEDs) of the five radio sources to characterize their host galaxies in terms of stellar mass and star formation rate. We observed the LLRGs with the IRAM-30m telescope to search for CO emission. We then searched for dense megaparsec-scale overdensities associated with the LLRGs using photometric redshifts of galaxies and the Poisson Probability Method, which we have upgraded using an approach based on the wavelet-transform (wPPM), to ultimately characterize the overdensity in the projected space and estimate the radio galaxy miscentering. Color-color and colormagnitude plots were then derived for the fiducial cluster members, selected using photometric redshifts. Results. Our IRAM-30m observations yielded upper limits to the CO emission of the LLRGs, at z = 0.39, 0.61, 0.91, 0.97, and 2.6. For the most distant radio source, COSMOS-FRI 70 at z = 2.6, a hint of CO(7→6) emission is found at 2.2σ. The upper limits found for the molecular gas content M(H 2 )/M <0.11, 0.09, 1.8, 1.5, and 0.29, respectively, and depletion time τ dep (0.2 − 7) Gyr of the five LLRGs are overall consistent with the corresponding values of main sequence field galaxies. Our SED modeling implies large stellar-mass estimates in the range log(M /M ) = 10.9 − 11.5, typical for giant ellipticals. Both our wPPM analysis and the cross-matching of the LLRGs with existing cluster/group catalogs suggest that the megaparsec-scale overdensities around our LLRGs are rich ( 10 14 M ) groups and show a complex morphology. The color-color and color-magnitude plots suggest that the LLRGs are consistent with being star forming and on the high-luminosity tail of the red sequence. The present study thus increases the still limited statistics of distant cluster core galaxies with CO observations. Conclusions. The radio galaxies of this work are excellent targets for ALMA as well as next-generation telescopes such as the James Webb Space Telescope.

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“…Indeed the majority of the most distant clusters currently known were selected on the basis of Spitzer mid-infrared data and confirmed with Hubble grism spectroscopy. This includes clusters at z=1.75 , z=1.80 (Newman et al 2014), z=1.89 (Zeimann et al 2012), and our own recent confirmation of one evolved cluster and one younger forming structure at z=2.00 and z=1.99, respectively (Noirot et al 2016;hereafter N16).…”

Section: Introductionmentioning

confidence: 99%

HST Grism Confirmation of 16 Structures at 1.4 < z < 2.8 from the Clusters Around Radio-Loud AGN (CARLA) Survey

Noirot

Stern

Mei

et al. 2018

ApJ

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We report spectroscopic results from our 40-orbit Hubble Space Telescope slitless grism spectroscopy program observing the 20 densest Clusters Around Radio-Loud AGN (CARLA) candidate galaxy clusters at 1.4<z<2.8. These candidate rich structures, among the richest and most distant known, were identified on the basis of [3.6]-[4.5] color from a 408hr multi-cycle Spitzer program targeting 420 distant radio-loud AGN. We report the spectroscopic confirmation of 16 distant structures at 1.4<z<2.8 associated with the targeted powerful highredshift radio-loud AGN. We also report the serendipitous discovery and spectroscopic confirmation of seven additional structures at 0.87<z<2.12 not associated with the targeted radio-loud AGN. We find that 10 10 -10 11 M e member galaxies of our confirmed CARLA structures form significantly fewer stars than their field counterparts at all redshifts within 1.4z2. We also observe higher star-forming activity in the structure cores up to z=2, finding similar trends as cluster surveys at slightly lower redshifts (1.0 < z < 1.5). By design, our efficient strategy of obtaining just two grism orbits per field only obtains spectroscopic confirmation of emission line galaxies. Deeper spectroscopy will be required to study the population of evolved, massive galaxies in these (forming) clusters. Lacking multi-band coverage of the fields, we adopt a very conservative approach of calling all confirmations "structures," although we note that a number of features are consistent with some of them being bona fide galaxy clusters. Together this survey represents a unique and large homogenous sample of spectroscopically confirmed structures at high redshifts, potentially more than doubling the census of confirmed, massive clusters at z>1.4.

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HST GRISM CONFIRMATION OF TWO z ∼ 2 STRUCTURES FROM THE CLUSTERS AROUND RADIO-LOUD AGN (CARLA) SURVEY

Cited by 35 publications

References 97 publications

Massive galaxies on the road to quenching: ALMA observations of powerful high redshift radio galaxies

Massive galaxies on the road to quenching: ALMA observations of powerful high redshift radio galaxies

Molecular gas in radio galaxies in dense megaparsec-scale environments at z = 0.4–2.6

HST Grism Confirmation of 16 Structures at 1.4 < z < 2.8 from the Clusters Around Radio-Loud AGN (CARLA) Survey

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