Ashby, M.

Blanton, E.

Brodwin, M.

Buiten, V.

Cai, Z.

Gal, R.

Golden-Marx, E.

Lemaux, B.

Lubin, L.

Moravec, E.

Paterno-Mahler, R.

Rottgering, H.

Sarkovic, V.

Shen, L.

Tomczak, A.

Weeren, R. van

Building a map of galaxy cluster evolution requires clusters spanning a range of redshifts, masses, and dynamical and evolutionary states. One way to build this sample is with radio AGNs, which have long been used to trace clusters at higher redshift. Specifically, bent, double-lobed radio sources are an effective tracer of clusters. Bent radio sources have a characteristic “C” shape, which is created when ram pressure from a dense gaseous medium, like the ICM, bends the radio lobes. Using the high-z Clusters Occupied by Bent Radio AGN (COBRA) survey, we identify a large sample of high-z cluster/protocluster candidates hosting bent AGNs. Using optical and IR images, we find strong red sequence populations in 39 cluster candidates at 0.35 < z < 2.2. In these clusters, we probe the red sequence to determine if BCGs preferentially host high-z bent AGNs. By correlating the distribution of red sequence galaxies in each cluster with the bending angle, we find that richer clusters host narrower bent AGNs. If ICM density scales with richness, the appearance of narrower bent AGNs may indicate which clusters have a denser or earlier forming ICM. Lastly, using VLA FIRST, VLASS, and LOFAR observations, we measure spectral indices for our high-z bent AGNs to further determine what causes the morphology of these bent radio sources and tease potential differences in the ICM distribution in our clusters

Golden-Marx, Emmet

Blanton, Elizabeth

Cai, Zheng

Paterno-Mahler, Rachel

Brodwin, Mark

Ashby, Matthew

Lemaux, Brian

Moravec, Emily

Shen, Lu

Lubin, Lori

Gal, Roy

Tomczak, Adam

Rottgering, Huub

van Weeren, Reinout

Buiten, Victorine

Sarkovic, Vanja

ZENODO

Where the Wild Things Are: Galaxy Evolution and Radio Source Properties in the High-z COBRA Survey

Leiden University Scholary Publications

Where the wild things are: galaxy evolution and radio source properties in the High-z COBRA surveyGolden-Marx, E.; Blanton, E.; Cai, Z.; Paterno-Mahler, R.; Brodwin, M.; Ashby, M.; ... ; Sarkovic, V.CitationGolden-Marx, E., Blanton, E., Cai, Z., Paterno-Mahler, R., Brodwin, M., Ashby, M., … Sarkovic, V. (2021). Where the wild things are: galaxyevolution and radio source properties in the High-z COBRA survey, 51. doi:10.5281/zenodo.5009014 Version: Publisher's VersionLicense: Creative Commons CC BY 4.0 licenseDownloadedfrom: https://hdl.handle.net/1887/3275260 Note: To cite this publication please use the final published version (if applicable).Where the Wild Things Are: Galaxy Evolution and Radio Source Properties in the High-z COBRA SurveyEmmet Golden-Marxemmetgm@bu.eduTsinghua UniversityGalaxy Cluster Formation 2021 – June 18, 2021Elizabeth Blanton, Zheng Cai, Rachel Paterno-Mahler, Mark Brodwin, Matt Ashby, Brian Lemaux, Emily Moravec, Lu Shen, Lori Lubin, Roy Gal, Adam Tomczak, Huub Röttgering, Reinout van Weeren, Victorine Buiten, Vanja Sarkovic1The High-z Clusters Occupied by Bent Radio AGN (COBRA) Survey• Sample of 646 bent, double-lobed radio sources selected from the VLA FIRST survey (Paterno-Mahler et al. 2017)• 0.3 < z < 3.0 • 41 spectroscopically confirmed quasars• Observations: Optical (Lowell Discovery Telescope – 4.3m), IR (Spitzer)Waveband Number of fields3.6μm 6464.5μm 135i-band 90r-band 38 2Bent, Double-Lobed Radio Sources• The unique “C” shape of bent radio sources is caused by ram pressure acting on the radio lobes• Most commonly, this pressure is caused by the relative motion between the galaxy and the ICM (e.g., Owen & Rudnick 1976)• At low redshift, bent sources are commonly in galaxy clusters(e.g., Blanton et al. 2000, Wing & Blanton et al. 2011, Garon et al. 2019))NRAO/AUI & O’Dea & Owen (1986)3Question 1Are high-z bent, double-lobed radio sources found in galaxy clusters characterized by strong red sequences? 4The Search for Red Sequence Galaxies• Estimate the red sequence color based on the host galaxy +/- 0.15  (red circles) (e.g., Blakeslee et al. 2003; Mei et al.𝜎 2006, 2009; Snyder et al. 2012; Lemaux et al. 2012; Cerulo et al. 2016)• Search the combined Spitzer/LDT fov for all red sequence galaxies to best identify the peak surface density of red galaxies• Define cluster candidates as a 2𝜎 overdensity in a 1’ region relative to the backgroundCOBRA121712.2+241525 COBRA170614.5+243707Golden-Marx et al. 2019, 20215z ~ 0.90 z ~ 0.71Further Verification – The Combined Overdensity• Weight the likelihood of each galaxy (red sequence, redder, and bluer) being a cluster member at our redshift estimate• Using spectroscopic and photometric redshifts and optical/IR imaging from the ORELSE survey (Lubin et al. 2009) • Identify 39 high-z cluster candidates at 0.35 < z < 2.2Golden-Marx et al. 20196The Location of Bent Sources in COBRA Clusters• Sakelliou & Merrifield (2000) found that the 11 of 16 of their low-z bent sources are within 300kpc (1 cluster core radius) of the cluster center• Similarly, Golden-Marx et al. (2021) found 24 of 39 are within 300kpc of the cluster centerSakelliou & Merrifield 2000 Golden-Marx et al. 20217Are Bent Radio Source Host Galaxies Proto-BCGs?• Identify the BCG as the brightest red sequence galaxy (exclude quasars)• 55% of our radio hosts are BCGs (Golden-Marx et al. 2021)8COBRA113733.8+300010 z = 0.96Golden-Marx et al. 2019COBRA123940.7+280828 z ~ 0.92Do COBRA proto-BCGs trace the overall cluster richness?• Among the richest COBRA clusters (> 3.5𝜎), we find a strong correlation between the absolute magnitude of the BCG and the combined overdensity• Could hint at the possibility of these systems being further along their evolutionary paths (e.g., Lin & Mohr 2004, Wechsler & Tinker 2018)Golden-Marx et al. 20219Question 2What are the radio properties of the bent radio sources and are they linked to environment? 10Measuring the Opening Angle• Measure the opening angle based on the detected radio components in the VLA FIRST catalog• 75% are WATs (> 90o)Golden-Marx et al. 2021 11COBRA074410.9+274011z ~ 1.3Does the Opening Angle Correlate with Environment?• Find a negative correlation between the size of the opening angle and cluster richness• If richer clusters have a denser ICM, this may imply the ICM density is the dominant driver of the bent morphology (not infall velocity); (e.g., Hardcastle et al. 2005, Morsony et al. 2013)Golden-Marx et al. 2021 12Where is the Bent Radio Source?• Sakelliou & Merrifield (2000) found that the overwhelming majority of their low-z bent sources are infallingInfallingOutgoingGolden-Marx et al. 202113COBRA074410.9+274011z ~ 1.3Have bent AGNs passed through the cluster center?• 11 sources are outgoing, 3 are infalling, and 22 are intermediate• The farthest sources from the cluster center are infalling or intermediate• This might imply that high-z bent sources don’t follow radial paths or the ICM is not dense enough to thoroughly disrupt the radio lobesOutgoingInfal l ingGolden-Marx et al. 202114Additional Radio ObservationsLOFAR (0.143GHz) VLA FIRST (1.44GHz) VLASS (3.0GHz)15• 21 COBRA red sequence clusters have radio observations in LOFAR• Aim to characterize the energetics of bent radio sources and trace any lobe asymmetriesGolden-Marx et al. (in prep)PreliminarySpectral Index Maps• a16Golden-Marx et al. (in prep)z ~ 1.35z ~ 1.75z ~ 1.3z ~ 1.20z = 0.96Preliminary Correlations between the Spectral Index and Radio/Host Parameters• Brighter host galaxies have radio sources with flatter core spectral indices17Golden-Marx et al. (in prep)Conclusions• Identify 39 red sequence cluster candidates at   0.35 < z < 2.2• The bent AGN is not necessarily centrally located• 55% of host galaxies are proto-BCGs• In the richest clusters, these proto-BCGs appear to trace overall cluster richness• Richer clusters on average host narrower bent radio sources• Identify many potentially outgoing radio sources• May indicate these galaxies follow non-radial/circular orbits, or are not disrupted upon falling through the cluster center• Began the first study of high-z bent radio source spectral indices 18

Where the wild things are: galaxy evolution and radio source properties in the High-z COBRA survey

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Where the wild things are: galaxy evolution and radio source properties in the High-z COBRA survey

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Leiden University Scholary Publications