Publication Search Results

ID: 159555
Type: article
Authors: Paggi, A.; Massaro, F.; Peña-Herazo, H. A.; Missaglia, V.; Ricci, F.; Stuardi, C.; Kraft, R. P.; Tremblay, G. R.; Baum, S. A.; Wilkes, B. J.
Abstract: Context. The diffuse X-ray emission surrounding radio galaxies is generally interpreted either as due to inverse Compton scattering of nonthermal radio-emitting electrons on the cosmic microwave background (IC/CMB), or as due to thermal emission arising from the hot gas of the intergalactic medium (IGM) permeating galaxy clusters hosting such galaxies, or as a combination of both. In this work, we present an imaging and spectral analysis of Chandra observations for the radio galaxy 3C 187 to investigate its diffuse X-ray emission and constrain the contribution of these various physical mechanisms.
Aims: The main goals of this work are the following: (i) to evaluate the extension of the diffuse X-ray emission from this source; (ii) to investigate the two main processes, IC/CMB and thermal emission from the IGM, which can account for the origin of this emission; and (iii) to test the possibility that 3C 187 belongs to a cluster of galaxies, which can account for the observed diffuse X-ray emission.
Methods: To evaluate the extension of the X-ray emission around 3C 187, we extracted surface flux profiles along and across the radio axis. We also extracted X-ray spectra in the region of the radio lobes and in the cross-cone region to estimate the contribution of the nonthermal (IC/CMB) and thermal (IGM) processes to the observed emission, making use of radio (VLA and GMRT) data to investigate the multiwavelength emission arising from the lobes. We collected Pan-STARRS photometric data to investigate the presence of a galaxy cluster hosting 3C 187, looking for the presence of a "red sequence" in the source field in the form of a tight clustering of galaxies in the color space. In addition, we made use of observations performed with the COSMOS spectrograph at the Victor Blanco Telescope to estimate the redshift of the sources in the field of 3C 187 to verify if they are gravitationally bound, as we would expect in a cluster of galaxies.
Results: The diffuse X-ray emission around 3C 187 is found to extend in the soft 0.3 - 3 keV band up to ∼850 kpc along the radio lobe direction and ∼530 kpc in the cross-cone direction, and it appears enhanced in correspondence with the radio lobes. Spectral X-ray analysis in the cross-cones indicates a thermal origin for the emission in this region with a temperature ∼4 keV. In the radio lobes, the X-ray spectral analysis in combination with the radio data suggests a dominant IC/CMB radiation in these regions, however we do not rule out a significant thermal contribution. Assuming that the radiation observed in the radio lobes is due to the IGM, the emission from the N and S cones can be interpreted as arising from hot gas with temperatures of ∼3 keV and ∼5 keV, respectively, and found to be in pressure equilibrium with the surrounding gas. Using Pan-STARRS optical data we found that 3C 187 belongs to a red sequence of ∼40 optical sources in the field whose color distribution is significantly different from background sources. We were able to collect optical spectra for only one of these cluster candidates and for 22 field (i.e., noncluster candidates) sources. While the latter show stellar spectra, the former feature a galactic spectrum with a redshift close to 3C 187 nucleus.
Conclusions: The diffuse X-ray emission around 3C 187 is elongated along the radio axis and enhanced in correspondence with the radio lobes. This indicates a morphological connection between the emission in the two energy bands and thus suggests a dominating IC/CMB mechanism in these regions. This scenario is reinforced by multiwavelength radio X-ray emission, which in these regions is compatible with IC/CMB radiation. The X-ray spectral analysis however does not rule out a significant contribution to the observed emission from thermal gas, which would be able to emit over tens of gigayears and in pressure equilibrium with the surroundings. Optical data indicate that 3C 187 may belong to a cluster of galaxies, whose IGM would contribute to the X-ray emission observed around the source. Additional X-ray and optical spectroscopic observations are however needed to secure these results and get a more clear picture of the physical processes at play in 3C 187.

ID: 155702
Type: article
Authors: Edwards, Louise O. V.; Salinas, Matthew; Stanley, Steffanie; Holguin West, Priscilla E.; Trierweiler, Isabella; Alpert, Hannah; Coelho, Paula; Koppaka, Saisneha; Tremblay, Grant R.; Martel, Hugo; Li, Yuan
Abstract: The formation and evolution of local brightest cluster galaxies (BCGs) is investigated by determining the stellar populations and dynamics from the galaxy core, through the outskirts and into the intracluster light (ICL). Integral spectroscopy of 23 BCGs observed out to 4 r_e is collected and high signal-to-noise regions are identified. Stellar population synthesis codes are used to determine the age, metallicity, velocity, and velocity dispersion of stars within each region. The ICL spectra are best modelled with populations that are younger and less metal-rich than those of the BCG cores. The average BCG core age of the sample is 13.3± 2.8 Gyr and the average metallicity is [Fe/H] = 0.30± 0.09, whereas for the ICL the average age is 9.2± 3.5 Gyr and the average metallicity is [Fe/H] = 0.18± 0.16. The velocity dispersion profile is seen to be rising or flat in most of the sample (17/23), and those with rising values reach the value of the host cluster's velocity dispersion in several cases. The most extended BCGs are closest to the peak of the cluster's X-ray luminosity. The results are consistent with the idea that the BCG cores and inner regions formed quickly and long ago, with the outer regions and ICL forming more recently, and continuing to assemble through minor merging. Any recent star formation in the BCGs is a minor component, and is associated with the cluster cool core status.

ID: 157477
Type: article
Authors: Jimenez-Gallardo, A.; Massaro, F.; Prieto, M. A.; Missaglia, V.; Stuardi, C.; Paggi, A.; Ricci, F.; Kraft, Ralph P.; Liuzzo, E.; Tremblay, Grant R.; Baum, S. A.; O'Dea, C. P.; Wilkes, Belinda J.; Kuraszkiewicz, Joanna; Forman, William R.; Harris, Dan E.
Abstract: We present the analysis of nine radio sources belonging to the Third Cambridge Revised catalog (3CR) observed with Chandra during Cycle 20 in the redshift range between 1.5 and 2.5. This study completes the 3CR Chandra Snapshot Survey thus guaranteeing the X-ray coverage of all 3CR sources identified to date. This sample lists two compact steep spectrum sources, four radio galaxies, and three quasars. We detected X-ray emission from all nuclei, with the only exception of 3C 326.1 and 3C 454.1 and from radio lobes in six out of nine sources at a level of confidence larger than ∼5σ. We measured X-ray fluxes and luminosities for all nuclei and lobes in the soft (0.5-1 keV), medium (1-2 keV), and hard (2-7 keV) X-ray bands. Since the discovered X-ray extended emission is spatially coincident with the radio structure in all cases, its origin could be due to inverse Compton (IC) scattering of the cosmic microwave background (CMB) occurring in radio lobes.

ID: 155681
Type: article
Authors: Li, Yuan; Gendron-Marsolais, Marie-Lou; Zhuravleva, Irina; Xu, Siyao; Simionescu, Aurora; Tremblay, Grant R.; Lochhaas, Cassandra; Bryan, Greg L.; Quataert, Eliot; Murray, Norman W.; Boselli, Alessandro; Hlavacek-Larrondo, Julie; Zheng, Yong; Fossati, Matteo; Li, Miao; Emsellem, Eric; Sarzi, Marc; Arzamasskiy, Lev; Vishniac, Ethan T.
Abstract: Supermassive black holes (SMBHs) are thought to provide energy that prevents catastrophic cooling in the centers of massive galaxies and galaxy clusters. However, it remains unclear how this "feedback" process operates. We use high-resolution optical data to study the kinematics of multiphase filamentary structures by measuring the velocity structure function (VSF) of the filaments over a wide range of scales in the centers of three nearby galaxy clusters: Perseus, A2597, and Virgo. We find that the motions of the filaments are turbulent in all three clusters studied. There is a clear correlation between features of the VSFs and the sizes of bubbles inflated by SMBH-driven jets. Our study demonstrates that SMBHs are the main driver of turbulent gas motions in the centers of relaxed galaxy clusters and suggests that this turbulence is an important channel for coupling feedback to the environment. Our measured amplitude of turbulence is in good agreement with Hitomi Doppler line broadening measurement and X-ray surface-brightness fluctuation analysis, suggesting that the motion of the cold filaments is well-coupled to that of the hot gas. The smallest scales that we probe are comparable to the mean free path in the intracluster medium. Our direct detection of turbulence on these scales provides the clearest evidence to date that isotropic viscosity is suppressed in the weakly collisional, magnetized intracluster plasma.

ID: 156819
Type: article
Authors: Nulsen, Susan; Kraft, Ralph; Germain, G.; Dunn, William; Tremblay, Grant; Beegle, L.; Branduardi-Raymont, G.; Bulbul, Esra; Elsner, R.; Hodyss, R.; Vance, S.
Abstract: We analyze archival Chandra X-ray Observatory observations of Jupiter to search for emission from the Galilean moons. X-ray emission has previously been reported from Io and Europa using a subset of these data. We confirm this detection, and marginally detect X-ray emission from both Ganymede and Callisto as well. The X-ray spectrum of Europa is strongly peaked around the neutral oxygen fluorescence line (525 eV), while Io's has peaks at both oxygen and sulfur (2308 eV) plus a broad continuum between 350 and 5000 eV. Ganymede's spectrum is similar to Io's, but without the sulfur peak. A few events, mostly clustered around the oxygen line, are detected from Callisto. Using measurements by the Galileo mission of the specific intensity of ambient protons and electrons, we model the X-ray spectra and flux of the moons from two processes: particle-induced X-ray emission (PIXE) from the impact of energetic protons and X-ray emission from electron bremsstrahlung. With uncertainties of a factor of a few, the electron bremsstrahlung and PIXE models overestimate the X-ray flux from Europa, preventing us from making a definitive statement about the origin of the X-ray emission. The PIXE model of Io predicts emission lines at O and S similar to those observed, but underestimates their flux by nearly two orders of magnitude. Based on this discrepancy in the PIXE flux, combined with the detected broadband continuum in the spectrum, we conclude that the X-ray emission from Io is due to electron bremsstrahlung. Likewise, because of Ganymede's broad continuum, we tentatively conclude that its X-ray emission is also due to electron bremsstrahlung. Callisto is too faint in the X-rays to draw any conclusion. Obtaining in situ X-ray observations of the moons would provide a direct measurement of their elemental composition.

ID: 157864
Type: article
Authors: Rose, Tom; Edge, A. C.; Combes, F.; Hamer, S.; McNamara, B. R.; Russell, H.; Gaspari, M.; Salomé, P.; Sarazin, C.; Tremblay, Grant R.; Baum, S. A.; Bremer, M. N.; Donahue, M.; Fabian, A. C.; Ferland, G.; Nesvadba, N.; O'Dea, C.; Oonk, J. B. R.; Peck, A. B.
Abstract: We present Atacama Large Millimetre/submillimetre Array observations of the brightest cluster galaxy Hydra-A, a nearby (z = 0.054) giant elliptical galaxy with powerful and extended radio jets. The observations reveal CO(1-0), CO(2-1), ¹³CO(2-1), CN(2-1), SiO(5-4), HCO⁺(1-0), HCO⁺(2-1), HCN(1-0), HCN(2-1), HNC(1-0), and H₂CO(3-2) absorption lines against the galaxy's bright and compact active galactic nucleus. These absorption features are due to at least 12 individual molecular clouds that lie close to the centre of the galaxy and have velocities of approximately -50 to +10 km s^-1 relative to its recession velocity, where positive values correspond to inward motion. The absorption profiles are evidence of a clumpy interstellar medium within brightest cluster galaxies composed of clouds with similar column densities, velocity dispersions, and excitation temperatures to those found at radii of several kpc in the Milky Way. We also show potential variation in a ∼10 km s^-1 wide section of the absorption profile over a 2 yr time-scale, most likely caused by relativistic motions in the hot spots of the continuum source that change the background illumination of the absorbing clouds.

ID: 158657
Type: article
Authors: Stroe, Andra; Hussaini, Maryam; Husemann, Bernd; Sobral, David; Tremblay, Grant
Abstract: Galaxy clusters grow by merging with other clusters, giving rise to Mpc-wide shock waves that travel at 1000-2500 km s^-1 through the intracluster medium. To study the effects of merger shocks on the properties of cluster galaxies, we present the first spatially resolved spectroscopic view of five Ha-emitting galaxies located in the wake of shock fronts in the low redshift (z ˜ 0.2), massive (˜2 × 10¹⁵M_?), post-core passage merging cluster, CIZA J2242.8+5301 (nicknamed the "Sausage"). Our Gemini/Gemini Multi-Object Spectrograph-North integral field unit (IFU) observations, designed to capture Ha and [N II] emission, reveal the nebular gas distribution, kinematics, and metallicities in the galaxies over >16 kpc scales. While the galaxies show evidence for rotational support, the flux and velocity maps have complex features like tails and gas outflows aligned with the merger axis of the cluster. With gradients that are incompatible with inside-out disk growth, the metallicity maps are consistent with sustained star formation (SF) throughout and outside of the galactic disks. In combination with previous results, these pilot observations provide further evidence of a likely connection between cluster mergers and SF triggering in cluster galaxies, a potentially fundamental discovery revealing the interaction of galaxies with their environment.

ID: 150452
Type: article
Authors: Allison, J. R.; Mahony, E. K.; Moss, V. A.; Sadler, E. M.; Whiting, M. T.; Allison, R. F.; Bland-Hawthorn, J.; Curran, S. J.; Emonts, B. H. C.; Lagos, C. D. P.; Morganti, Raffaella; Tremblay, G.; Zwaan, M.; Anderson, C. S.; Bunton, J. D.; Voronkov, M. A.
Abstract: Cold neutral gas is a key ingredient for growing the stellar and central black hole mass in galaxies throughout cosmic history. We have used the Atacama Large Millimetre Array to detect a rare example of redshifted ¹²CO (2-1) absorption in PKS B1740-517, a young (t ˜ 1.6 × 10³ yr) and luminous (L_{5 GHz} ≈ 6.6 × 10^{43} erg s^-1) radio galaxy at z = 0.44 that is undergoing a tidal interaction with at least one lower mass companion. The coincident H I 21-cm and molecular absorption have very similar line profiles and reveal a reservoir of cold gas (M_gas ˜ 10⁷-10⁸ M_⊙), likely distributed in a disc or ring within a few kiloparsecs of the nucleus. A separate H I component is kinematically distinct and has a very narrow line width (Δv_FWHM ≲ 5 km s^-1), consistent with a single diffuse cloud of cold (T_k ˜ 100 K) atomic gas. The ¹²CO (2-1) absorption is not associated with this component, which suggests that the cloud is either much smaller than 100 pc along our sight line and/or located in low-metallicity gas that was possibly tidally stripped from the companion. We argue that the gas reservoir in PKS B1740-517 may have accreted on to the host galaxy ˜ 50 Myr before the young radio AGN was triggered, but has only recently reached the nucleus. This is consistent with the paradigm that powerful luminous radio galaxies are triggered by minor mergers and interactions with low-mass satellites and represent a brief, possibly recurrent, active phase in the life cycle of massive early-type galaxies.

ID: 154554
Type: article
Authors: Balmaverde, B.; Capetti, A.; Marconi, A.; Venturi, G.; Chiaberge, M.; Baldi, R. D.; Baum, S.; Gilli, R.; Grandi, P.; Meyer, E.; Miley, G.; O'Dea, C.; Sparks, W.; Torresi, E.; Tremblay, Grant
Abstract: We present observations of a complete sub-sample of 20 radio galaxies from the Third Cambridge Catalog (3C) with redshift ^-18 erg s^-1 cm^-2 arcsec^-2), these observations reveal emission line structures extending to several tens of kiloparsec in most objects. In nine sources the gas velocity shows ordered rotation, but in the other cases it is highly complex. 3C sources show a connection between radio morphology and emission line properties. Whereas, in three of the four Fanaroff and Riley Class I radio galaxies (FR Is), the line emission regions are compact, ̃1 kpc in size; in all but one of the Class II radiogalaxies FR IIs, we detected large scale structures of ionized gas with a median extent of 17 kpc. Among the FR IIs, those of high and low excitation show extended gas structures with similar morphological properties, suggesting that they both inhabit regions characterized by a rich gaseous environment on kpc scale.

ID: 155237
Type: article
Authors: Calzadilla, Michael S.; Russell, Helen R.; McDonald, Michael A.; Fabian, Andrew C.; Baum, Stefi A.; Combes, Françoise; Donahue, Megan; Edge, Alastair C.; McNamara, Brian R.; Nulsen, Paul E. J.; O'Dea, Christopher P.; Oonk, J. B. Raymond; Tremblay, Grant R.; Vantyghem, Adrian N.
Abstract: We present new, deep (245 ks) Chandra observations of the galaxy cluster Abell 1664 (z = 0.1283). These images reveal rich structure, including elongation and accompanying compressions of the X-ray isophotes in the NE-SW direction, suggesting that the hot gas is sloshing in the gravitational potential. This sloshing has resulted in cold fronts, at distances of 50, 110, and 325 kpc from the cluster center. Our results indicate that the core of A1664 is highly disturbed, as the global metallicity and cooling time flatten at small radii, implying mixing on a range of scales. The central active galactic nucleus (AGN) appears to have recently undergone a mechanical outburst, as evidenced by our detection of cavities. These cavities are the X-ray manifestations of radio bubbles inflated by the AGN and may explain the motion of cold molecular CO clouds previously observed with the Atacama Large Millimeter Array (ALMA). The estimated mechanical power of the AGN, using the minimum energy required to inflate the cavities as a proxy, is {P}_cav}=(1.1+/- 1.0)× {10}⁴⁴ erg s^-1, which may be enough to drive the molecular gas flows, and offset the cooling luminosity of the intracluster medium, at {L}_cool}=(1.53+/- 0.01)× {10}⁴⁴ erg s^-1. This mechanical power is orders of magnitude higher than the measured upper limit on the X-ray luminosity of the central AGN, suggesting that its black hole may be extremely massive and/or radiatively inefficient. We map temperature variations on the same spatial scale as the molecular gas and find that the most rapidly cooling gas is mostly coincident with the molecular gas reservoir centered on the brightest cluster galaxy's systemic velocity observed with ALMA and may be fueling cold accretion onto the central black hole.

ID: 154619
Type: article
Authors: Gaspari, M.; Eckert, D.; Ettori, S.; Tozzi, P.; Bassini, L.; Rasia, E.; Brighenti, F.; Sun, M.; Borgani, S.; Johnson, S. D.; Tremblay, Grant R.; Stone, J. M.; Temi, P.; Yang, H. -Y K.; Tombesi, F.; Cappi, M.
Abstract: We carry out a comprehensive Bayesian correlation analysis between hot halos and direct masses of supermassive black holes (SMBHs), by retrieving the X-ray plasma properties (temperature, luminosity, density, pressure, and masses) over galactic to cluster scales for 85 diverse systems. We find new key scalings, with the tightest relation being {M}_\bullet -{\text{}}{T}_{{x}}, followed by {M}_\bullet -{\text{}}{L}_{{x}}. The tighter scatter (down to 0.2 dex) and stronger correlation coefficient of all the X-ray halo scalings compared with the optical counterparts (as the {M}_\bullet -{σ }_{{e}}) suggest that plasma halos play a more central role than stars in tracing and growing SMBHs (especially those that are ultramassive). Moreover, {M}_\bullet correlates better with the gas mass than dark matter mass. We show the important role of the environment, morphology, and relic galaxies/coronae, as well as the main departures from virialization /self-similarity via the optical/X-ray fundamental planes. We test the three major channels for SMBH growth: hot/Bondi-like models have inconsistent anticorrelation with X-ray halos and too low feeding; cosmological simulations find SMBH mergers as subdominant over most of cosmic time and too rare to induce a central-limit-theorem effect; the scalings are consistent with chaotic cold accretion, the rain of matter condensing out of the turbulent X-ray halos that sustains a long-term self-regulated feedback loop. The new correlations are major observational constraints for models of SMBH feeding/feedback in galaxies, groups, and clusters (e.g., to test cosmological hydrodynamical simulations), and enable the study of SMBHs not only through X-rays, but also via the Sunyaev-Zel'dovich effect (Compton parameter), lensing (total masses), and cosmology (gas fractions).

ID: 155117
Type: article
Authors: Husemann, B.; Scharwächter, J.; Davis, T. A.; Pérez-Torres, M.; Smirnova-Pinchukova, I.; Tremblay, Grant R.; Krumpe, M.; Combes, F.; Baum, S. A.; Busch, G.; Connor, T.; Croom, S. M.; Gaspari, M.; Kraft, Ralph P.; O'Dea, C. P.; Powell, M.; Singha, M.; Urrutia, T.
Abstract: Context. Galaxy-wide outflows driven by star formation and/or an active galactic nucleus (AGN) are thought to play a crucial rule in the evolution of galaxies and the metal enrichment of the inter-galactic medium. Direct measurements of these processes are still scarce and new observations are needed to reveal the nature of outflows in the majority of the galaxy population. Aims: We combine extensive, spatially- resolved, multi-wavelength observations, taken as part of the Close AGN Reference Survey (CARS), for the edge-on disc galaxy HE 1353-1917 in order to characterise the impact of the AGN on its host galaxy via outflows and radiation. Methods: Multi-color broad-band photometry was combined with spatially-resolved optical, near-infrared (NIR) and sub-mm and radio observations taken with the Multi-Unit Spectroscopy Explorer (MUSE), the Near-infrared Integral Field Spectrometer (NIFS), the Atacama Large Millimeter Array (ALMA), and the Karl G. Jansky Very Large Array (VLA) to map the physical properties and kinematics of the multi-phase interstellar medium. Results: We detect a biconical extended narrow-line region ionised by the luminous AGN orientated nearly parallel to the galaxy disc, extending out to at least 25 kpc. The extra-planar gas originates from galactic fountains initiated by star formation processes in the disc, rather than an AGN outflow, as shown by the kinematics and the metallicity of the gas. Nevertheless, a fast, multi-phase, AGN-driven outflow with speeds up to 1000 km s^-1 is detected close to the nucleus at 1 kpc distance. A radio jet, in connection with the AGN radiation field, is likely responsible for driving the outflow as confirmed by the energetics and the spatial alignment of the jet and multi-phase outflow. Evidence for negative AGN feedback suppressing the star formation rate (SFR) is mild and restricted to the central kpc. But while any SFR suppression must have happened recently, the outflow has the potential to greatly impact the future evolution of the galaxy disc due to its geometrical orientation. Conclusions.. Our observations reveal that low- power radio jets can play a major role in driving fast, multi-phase, galaxy-scale outflows even in radio-quiet AGN. Since the outflow energetics for HE 1353-1917 are consistent with literature, scaling relation of AGN-driven outflows the contribution of radio jets as the driving mechanisms still needs to be systematically explored.

ID: 154607
Type: article
Authors: McDonald, M.; McNamara, B. R.; Voit, G. M.; Bayliss, M.; Benson, B. A.; Brodwin, M.; Canning, R. E. A.; Florian, M. K.; Garmire, G. P.; Gaspari, M.; Gladders, M. D.; Hlavacek-Larrondo, J.; Kara, E.; Reichardt, C. L.; Russell, H. R.; Saro, A.; Sharon, K.; Somboonpanyakul, T.; Tremblay, Grant R.; van Weeren, R. J.
Abstract: We present new, deep observations of the Phoenix cluster from Chandra, the Hubble Space Telescope, and the Karl Jansky Very Large Array. These data provide an order-of-magnitude improvement in depth and/or angular resolution over previous observations at X-ray, optical, and radio wavelengths. We find that the one-dimensional temperature and entropy profiles are consistent with expectations for pure-cooling models. In particular, the entropy profile is well fit by a single power law at all radii, with no evidence for excess entropy in the core. In the inner ∼10 kpc, the cooling time is shorter than any other known cluster by an order of magnitude, while the ratio of the cooling time to freefall time (t _cool/t _ff) approaches unity, signaling that the intracluster medium is unable to resist multiphase condensation on kpc scales. The bulk of the cooling in the inner ∼20 kpc is confined to a low-entropy filament extending northward from the central galaxy, with t _cool/t _ff ∼ 1 over the length of the filament. In this filament, we find evidence for ∼10¹⁰ M _☉ in cool (∼10⁴ K) gas (as traced by the [O II]λλ3726,3729 doublet), which is coincident with the low-entropy filament and absorbing soft X-rays. The bulk of this cool gas is draped around and behind a pair of X-ray cavities, presumably bubbles that have been inflated by radio jets. These data support a picture in which active galactic nucleus feedback is promoting the formation of a multiphase medium via uplift of low-entropy gas, either via ordered or chaotic (turbulent) motions.

ID: 154157
Type: article
Authors: Neumann, J.; Gadotti, D. A.; Wisotzki, L.; Husemann, B.; Busch, G.; Combes, F.; Croom, S. M.; Davis, T. A.; Gaspari, M.; Krumpe, M.; Pérez-Torres, M. A.; Scharwächter, J.; Smirnova-Pinchukova, I.; Tremblay, Grant R.; Urrutia, T.
Abstract: The absence of star formation in the bar region that has been reported for some galaxies can theoretically be explained by shear. However, it is not clear how star-forming (SF) bars fit into this picture and how the dynamical state of the bar is related to other properties of the host galaxy. We used integral-field spectroscopy from VLT/MUSE to investigate how star formation within bars is connected to structural properties of the bar and the host galaxy. We derived spatially resolved Hα fluxes from MUSE observations from the CARS survey to estimate star formation rates in the bars of 16 nearby (0.01 ¹⁰ M_☉ and 10¹¹ M_☉. We further performed a detailed multicomponent photometric decomposition on images derived from the data cubes. We find that bars clearly divide into SF and non-SF types, of which eight are SF and eight are non-SF. Whatever the responsible quenching mechanism is, it is a quick process compared to the lifetime of the bar. The star formation of the bar appears to be linked to the flatness of the surface brightness profile in the sense that only the flattest bars (n_bar≤0.4) are actively SF (SFR_b > 0.5 M_☉ yr^-1). Both parameters are uncorrelated with Hubble type. We find that star formation is 1.75 times stronger on the leading than on the trailing edge and is radially decreasing. The conditions to host non-SF bars might be connected to the presence of inner rings. Additionally, from testing an AGN feeding scenario, we report that the star formation rate of the bar is uncorrelated with AGN bolometric luminosity. The results of this study may only apply to type-1 AGN hosts and need to be confirmed for the full population of barred galaxies. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme(s) 094.B-0345(A) and 095.B-0015(A).

ID: 154609
Type: article
Authors: Olivares, V.; Salome, P.; Combes, F.; Hamer, S.; Guillard, P.; Lehnert, M. D.; Polles, F. L.; Beckmann, R. S.; Dubois, Y.; Donahue, M.; Edge, A.; Fabian, A. C.; McNamara, B.; Rose, T.; Russell, H. R.; Tremblay, Grant; Vantyghem, A.; Canning, R. E. A.; Ferland, G.; Godard, B.; Peirani, S.; Pineau des Forets, G.
Abstract: Multi-phase filamentary structures around brightest cluster galaxies (BCG) are likely a key step of AGN-feedback. We observed molecular gas in three cool cluster cores, namely Centaurus, Abell S1101, and RXJ1539.5, and gathered ALMA (Atacama Large Millimeter/submillimeter Array) and MUSE (Multi Unit Spectroscopic Explorer) data for 12 other clusters. Those observations show clumpy, massive, and long (3-25 kpc) molecular filaments, preferentially located around the radio bubbles inflated by the AGN. Two objects show nuclear molecular disks. The optical nebula is certainly tracing the warm envelopes of cold molecular filaments. Surprisingly, the radial profile of the Hα/CO flux ratio is roughly constant for most of the objects, suggesting that (i) between 1.2 and 6 times more cold gas could be present and (ii) local processes must be responsible for the excitation. Projected velocities are between 100 and 400 km s^-1, with disturbed kinematics and sometimes coherent gradients. This is likely due to the mixing in projection of several thin (and as yet) unresolved filaments. The velocity fields may be stirred by turbulence induced by bubbles, jets, or merger-induced sloshing. Velocity and dispersions are low, below the escape velocity. Cold clouds should eventually fall back and fuel the AGN. We compare the radial extent of the filaments, r_fil, with the region where the X-ray gas can become thermally unstable. The filaments are always inside the low-entropy and short-cooling-time region, where t_cool/t_{ff cool}/t_ff of 8-23 at r_fil, is likely due to (i) a more complex gravitational potential affecting the free- fall time t_ff (sloshing, mergers, etc.) and (ii) the presence of inhomogeneities or uplifted gas in the ICM, affecting the cooling time t_cool. For some of the sources, r_fil lies where the ratio of the cooling time to the eddy-turnover time, t_cool/t_eddy, is approximately unity.

ID: 154707
Type: article
Authors: Rose, Tom; Edge, A. C.; Combes, F.; Gaspari, M.; Hamer, S.; Nesvadba, N.; Peck, A. B.; Sarazin, C.; Tremblay, Grant R.; Baum, S. A.; Bremer, M. N.; McNamara, B. R.; O'Dea, C.; Oonk, J. B. R.; Russell, H.; Salomé, P.; Donahue, M.; Fabian, A. C.; Ferland, G.; Mittal, R.; Vantyghem, A.
Abstract: To advance our understanding of the fuelling and feedback processes which power the Universe's most massive black holes, we require a significant increase in our knowledge of the molecular gas which exists in their immediate surroundings. However, the behaviour of this gas is poorly understood due to the difficulties associated with observing it directly. We report on a survey of 18 brightest cluster galaxies lying in cool cores, from which we detect molecular gas in the core regions of eight via carbon monoxide (CO), cyanide (CN) and silicon monoxide (SiO) absorption lines. These absorption lines are produced by cold molecular gas clouds which lie along the line of sight to the bright continuum sources at the galaxy centres. As such, they can be used to determine many properties of the molecular gas which may go on to fuel supermassive black hole accretion and AGN feedback mechanisms. The absorption regions detected have velocities ranging from -45 to 283 km s^-1 relative to the systemic velocity of the galaxy, and have a bias for motion towards the host supermassive black hole. We find that the CN N = 0 - 1 absorption lines are typically 10 times stronger than those of CO J = 0 - 1. This is due to the higher electric dipole moment of the CN molecule, which enhances its absorption strength. In terms of molecular number density CO remains the more prevalent molecule with a ratio of CO/CN ̃10, similar to that of nearby galaxies. Comparison of CO, CN, and H I observations for these systems shows many different combinations of these absorption lines being detected.

ID: 151863
Type: article
Authors: Rose, Tom; Edge, A. C.; Combes, F.; Gaspari, M.; Hamer, S.; Nesvadba, N.; Russell, H.; Tremblay, G. R.; Baum, S. A.; O'Dea, C.; Peck, A. B.; Sarazin, C.; Vantyghem, A.; Bremer, M.; Donahue, M.; Fabian, A. C.; Ferland, G.; McNamara, B. R.; Mittal, R.; Oonk, J. B. R.; Salomé, P.; Swinbank, A. M.; Voit, M.
Abstract: Active galactic nuclei play a crucial role in the accretion and ejection of gas in galaxies. Although their outflows are well studied, finding direct evidence of accretion has proved very difficult and has so far been done for very few sources. A promising way to study the significance of cold accretion is by observing the absorption of an active galactic nucleus's extremely bright radio emission by the cold gas lying along the line of sight. As such, we present ALMA CO(1-0) and CO(2-1) observations of the Hydra-A brightest cluster galaxy (z = 0.054) which reveal the existence of cold, molecular gas clouds along the line of sight to the galaxy's extremely bright and compact mm-continuum source. They have apparent motions relative to the central supermassive black hole of between -43 and -4 km s^-1 and are most likely moving along stable, low ellipticity orbits. The identified clouds form part of a ˜10⁹ M_⊙, approximately edge-on disc of cold molecular gas. With peak CO(2-1) optical depths of τ = 0.88 ^{+0.06}_{-0.06}, they include the narrowest and by far the deepest absorption of this type which has been observed to date in a brightest cluster galaxy. By comparing the relative strengths of the lines for the most strongly absorbing region, we are able to estimate a gas temperature of 42^{+25}_{-11} K and line of sight column densities of N_{CO}=2^{+3}_{-1}× 10 ^{17} {cm}^{-2} and N_{H₂ }=7^{+10}_{-4}× 10 ^{20} {cm}^{-2}.

ID: 152932
Type: article
Authors: Smirnova-Pinchukova, I.; Husemann, B.; Busch, G.; Appleton, P.; Bethermin, M.; Combes, F.; Croom, S.; Davis, T. A.; Fischer, C.; Gaspari, M.; Groves, B.; Klein, R.; O'Dea, C. P.; Pérez-Torres, M.; Scharwächter, J.; Singha, M.; Tremblay, Grant R.; Urrutia, T.
Abstract: The [C II]λ158 μm line is one of the strongest far-infrared (FIR) lines and an important coolant in the interstellar medium of galaxies that is accessible out to high redshifts. The excitation of [C II] is complex and can best be studied in detail at low redshifts. Here we report the discovery of the highest global [C II] excess with respect to the FIR luminosity in the nearby AGN host galaxy HE 1353-1917. This galaxy is exceptional among a sample of five targets because the AGN ionization cone and radio jet directly intercept the cold galactic disk. As a consequence, a massive multiphase gas outflow on kiloparsec scales is embedded in an extended narrow-line region. Because HE 1353-1917 is distinguished by these special properties from our four bright AGN, we propose that a global [C II] excess in AGN host galaxies could be a direct signature of a multiphase AGN-driven outflow with a high mass-loading factor.

ID: 149183
Type: article
Authors: Astropy Collaboration; Price-Whelan, A. M.; Sipőcz, B. M.; Günther, H. M.; Lim, P. L.; Crawford, S. M.; Conseil, S.; Shupe, D. L.; Craig, M. W.; Dencheva, N.; Ginsburg, A.; VanderPlas, J. T.; Bradley, L. D.; Pérez-Suárez, D.; de Val-Borro, M.; Aldcroft, T. L.; Cruz, K. L.; Robitaille, T. P.; Tollerud, E. J.; Ardelean, C.; Babej, T.; Bach, Y. P.; Bachetti, M.; Bakanov, A. V.; Bamford, S. P.; Barentsen, G.; Barmby, P.; Baumbach, A.; Berry, K. L.; Biscani, F.; Boquien, M.; Bostroem, K. A.; Bouma, L. G.; Brammer, G. B.; Bray, E. M.; Breytenbach, H.; Buddelmeijer, H.; Burke, D. J.; Calderone, G.; Cano Rodríguez, J. L.; Cara, M.; Cardoso, J. V. M.; Cheedella, S.; Copin, Y.; Corrales, L.; Crichton, D.; D'Avella, D.; Deil, C.; Depagne, É.; Dietrich, J. P.; Donath, A.; Droettboom, M.; Earl, N.; Erben, T.; Fabbro, S.; Ferreira, L. A.; Finethy, T.; Fox, R. T.; Garrison, L. H.; Gibbons, S. L. J.; Goldstein, D. A.; Gommers, R.; Greco, J. P.; Greenfield, P.; Groener, A. M.; Grollier, F.; Hagen, A.; Hirst, P.; Homeier, D.; Horton, A. J.; Hosseinzadeh, G.; Hu, L.; Hunkeler, J. S.; Ivezić, Ž.; Jain, A.; Jenness, T.; Kanarek, G.; Kendrew, S.; Kern, N. S.; Kerzendorf, W. E.; Khvalko, A.; King, J.; Kirkby, D.; Kulkarni, A. M.; Kumar, A.; Lee, A.; Lenz, D.; Littlefair, S. P.; Ma, Z.; Macleod, D. M.; Mastropietro, M.; McCully, C.; Montagnac, S.; Morris, B. M.; Mueller, M.; Mumford, S. J.; Muna, D.; Murphy, N. A.; Nelson, S.; Nguyen, G. H.; Ninan, J. P.; Nöthe, M.; Ogaz, S.; Oh, S.; Parejko, J. K.; Parley, N.; Pascual, S.; Patil, R.; Patil, A. A.; Plunkett, A. L.; Prochaska, J. X.; Rastogi, T.; Reddy Janga, V.; Sabater, J.; Sakurikar, P.; Seifert, M.; Sherbert, L. E.; Sherwood-Taylor, H.; Shih, A. Y.; Sick, J.; Silbiger, M. T.; Singanamalla, S.; Singer, L. P.; Sladen, P. H.; Sooley, K. A.; Sornarajah, S.; Streicher, O.; Teuben, P.; Thomas, S. W.; Tremblay, Grant R.; Turner, J. E. H.; Terrón, V.; van Kerkwijk, M. H.; de la Vega, A.; Watkins, L. L.; Weaver, B. A.; Whitmore, J. B.; Woillez, J.; Zabalza, V.; Astropy Contributors
Abstract: The Astropy Project supports and fosters the development of open-source and openly developed Python packages that provide commonly needed functionality to the astronomical community. A key element of the Astropy Project is the core package astropy, which serves as the foundation for more specialized projects and packages. In this article, we provide an overview of the organization of the Astropy project and summarize key features in the core package, as of the recent major release, version 2.0. We then describe the project infrastructure designed to facilitate and support development for a broader ecosystem of interoperable packages. We conclude with a future outlook of planned new features and directions for the broader Astropy Project. .

ID: 145750
Type: article
Authors: Massaro, F.; Missaglia, V.; Stuardi, C.; Harris, D. E.; Kraft, R. P.; Paggi, A.; Liuzzo, E.; Tremblay, Grant R.; Baum, S. A.; O'Dea, C. P.; Wilkes, B. J.; Kuraszkiewicz, J.; Forman, W. R.
Abstract: This paper presents the analysis of Chandra X-ray snapshot observations of a subsample of the extragalactic sources listed in the revised Third Cambridge radio catalog (3CR), previously lacking X-ray observations and thus observed during Chandra Cycle 15. This data set extends the current Chandra coverage of the 3CR extragalactic catalog up to redshift z = 1.0. Our sample includes 22 sources consisting of 1 compact steep spectrum source, 3 quasars (QSOs), and 18 FR II radio galaxies. As in our previous analyses, here we report the X-ray detections of radio cores and extended structures (i.e., knots, hotspots, and lobes) for all sources in the selected sample. We measured their X-ray intensities in three energy ranges, soft (0.5--1 keV), medium (1--2 keV), and hard (2--7 keV), and we also performed standard X-ray spectral analysis for brighter nuclei. All radio nuclei in our sample have an X-ray counterpart. We also discovered X-ray emission associated with the eastern knot of 3CR 154, with radio hotspots in 3CR 41, 3CR 54, and 3CR 225B, and with the southern lobe of 3CR 107. Extended X-ray radiation around the nuclei 3CR 293.1 and 3CR 323 on a scale of few tens of kiloparsecs was also found. X-ray extended emission, potentially arising from the hot gas in the intergalactic medium and/or due to the high-energy counterpart of lobes, is detected for 3CR 93, 3CR 154, 3CR 292, and 3CR 323 over a scale of a few hundred kiloparsecs. Finally, this work also presents an update on the state-of-the-art of Chandra and XMM-Newton observations for the entire 3CR sample.