scholarly journals The Australia Telescope Large Area Survey: Measuring the AGN contribution to galaxies over cosmic time

2013 ◽  
Vol 9 (S304) ◽  
pp. 93-93
Author(s):  
Kate Chow
Keyword(s):  
Cosmic Time ◽  
Host Galaxy ◽  
Evolutionary Stage ◽  
Large Area ◽  
X Ray ◽  
Star Forming ◽  
Total Luminosity ◽  
The Galaxy ◽  
Area Survey ◽  
The Relationship

AbstractThe Australia Telescope Large Area Survey (ATLAS) is the widest deep radio survey ever attempted, covering ~7deg2 across its two fields, the Chandra Deep Field South (CDFS) and the European Large Area ISO Survey South 1 Region (ELAIS-S1). ATLAS has extensive multiwavelength data, including optical, infrared and X-ray, to complement its ~15μJy rms 1.4 GHz radio data. At these faint radio flux densities, the proportion of AGN to star-forming galaxies (SFGs) is high, and there are likely many composite objects, which have both an AGN and ongoing star formation. In ATLAS, we estimate that the number of AGN is approximately 50%, and this proportion will change with decreasing flux density. To understand the relationship between the AGN and the host galaxy, we need to measure the contribution of the AGN to the total luminosity, and determine how this varies with the evolutionary stage of the galaxy. Here I present results exploring the AGN contribution to galaxies over cosmic time, through the use of different multiwavelength discriminants.

scholarly journals The role of AGN activity in the building up of the BCG at z ∼ 1.6

2019 ◽  
Vol 15 (S356) ◽  
pp. 280-284
Author(s):  
Angela Bongiorno ◽  
Andrea Travascio
Keyword(s):  
Galaxy Cluster ◽  
Cluster Galaxy ◽  
X Ray ◽  
Groups Of Galaxies ◽  
Star Forming ◽  
The Core ◽  
The Galaxy ◽  
Multi Wavelength

AbstractXDCPJ0044.0-2033 is one of the most massive galaxy cluster at z ∼1.6, for which a wealth of multi-wavelength photometric and spectroscopic data have been collected during the last years. I have reported on the properties of the galaxy members in the very central region (∼ 70kpc × 70kpc) of the cluster, derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy, together with Chandra X-ray, ALMA and JVLA radio data.In the core of the cluster, we have identified two groups of galaxies (Complex A and Complex B), seven of them confirmed to be cluster members, with signatures of ongoing merging. These galaxies show perturbed morphologies and, three of them show signs of AGN activity. In particular, two of them, located at the center of each complex, have been found to host luminous, obscured and highly accreting AGN (λ = 0.4−0.6) exhibiting broad Hα line. Moreover, a third optically obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The AGN at the center of Complex B is detected in X-ray while the other two, and their companions, are spatially related to radio emission. The three AGN provide one of the closest AGN triple at z > 1 revealed so far with a minimum (maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN activity in a highly star-forming region associated to the crowded core of a galaxy cluster at z ∼ 1.6, suggests that these processes have a key role in shaping the nascent Brightest Cluster Galaxy, observed at the center of local clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033 could form a BCG of M* ∼ 1012Mȯ hosting a BH of 2 × 108−109Mȯ, in a time scale of the order of 2.5 Gyrs.

Tracing young SMBHs in the dusty distant universe – a Chandra view of DOGs

2020 ◽  
Vol 15 (S359) ◽  
pp. 17-21
Author(s):  
Karín Menéndez-Delmestre ◽  
Laurie Riguccini ◽  
Ezequiel Treister
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Far Infrared ◽  
Host Galaxy ◽  
X Ray ◽  
Star Forming ◽  
Near Ir ◽  
X Ray Imaging ◽  
Combined Use ◽  
Dusty Galaxies

AbstractThe coexistence of star formation and AGN activity has geared much attention to dusty galaxies at high redshifts, in the interest of understanding the origin of the Magorrian relation observed locally, where the mass of the stellar bulk in a galaxy appears to be tied to the mass of the underlying supermassive black hole. We exploit the combined use of far-infrared (IR) Herschel data and deep Chandra ˜160 ksec depth X-ray imaging of the COSMOS field to probe for AGN signatures in a large sample of >100 Dust-Obscured Galaxies (DOGs). Only a handful (˜20%) present individual X-ray detections pointing to the presence of significant AGN activity, while X-ray stacking analysis on the X-ray undetected DOGs points to a mix between AGN activity and star formation. Together, they are typically found on the main sequence of star-forming galaxies or below it, suggesting that they are either still undergoing significant build up of the stellar bulk or have started quenching. We find only ˜30% (6) Compton-thick AGN candidates (NH > 1024 cm–2), which is the same frequency found within other soft- and hard-X-ray selected AGN populations. This suggests that the large column densities responsible for the obscuration in Compton-thick AGNs must be nuclear and have little to do with the dust obscuration of the host galaxy. We find that DOGs identified to have an AGN share similar near-IR and mid-to-far-IR colors, independently of whether they are individually detected or not in the X-ray. The main difference between the X-ray detected and the X-ray undetected populations appears to be in their redshift distributions, with the X-ray undetected ones being typically found at larger distances. This strongly underlines the critical need for multiwavelength studies in order to obtain a more complete census of the obscured AGN population out to higher redshifts. For more details, we refer the reader to Riguccini et al. (2019).

scholarly journals Most of the cool CGM of star-forming galaxies is not produced by supernova feedback

2020 ◽  
Author(s):  
Andrea Afruni ◽  
Filippo Fraternali ◽  
Gabriele Pezzulli
Keyword(s):  
Galaxy Evolution ◽  
Cosmic Time ◽  
Energy Coupling ◽  
High Energy ◽  
Parametric Models ◽  
Star Forming ◽  
Galaxy Halos ◽  
The Galaxy ◽  
Supernova Explosions ◽  
Cool Gas

Abstract The characterization of the large amount of gas residing in the galaxy halos, the so called circumgalactic medium (CGM), is crucial to understand galaxy evolution across cosmic time. We focus here on the the cool (T ∼ 104 K) phase of this medium around star-forming galaxies in the local universe, whose properties and dynamics are poorly understood. We developed semi-analytical parametric models to describe the cool CGM as an outflow of gas clouds from the central galaxy, as a result of supernova explosions in the disc (galactic wind). The cloud motion is driven by the galaxy gravitational pull and by the interactions with the hot (T ∼ 106 K) coronal gas. Through a bayesian analysis, we compare the predictions of our models with the data of the COS-Halos and COS-GASS surveys, which provide accurate kinematic information of the cool CGM around more than 40 low-redshift star-forming galaxies, probing distances up to the galaxy virial radii. Our findings clearly show that a supernova-driven outflow model is not suitable to describe the dynamics of the cool circumgalactic gas. Indeed, to reproduce the data, we need extreme scenarios, with initial outflow velocities and mass loading factors that would lead to unphysically high energy coupling from the supernovae to the gas and with supernova efficiencies largely exceeding unity. This strongly suggests that, since the outflows cannot reproduce most of the cool gas absorbers, the latter are likely the result of cosmological inflow in the outer galaxy halos, in analogy to what we have previously found for early-type galaxies.

scholarly journals Redshift measurement through star formation

2019 ◽  
Vol 629 ◽  
pp. A7
Author(s):  
Mikkel O. Lindholmer ◽  
Kevin A. Pimbblet
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
Main Sequence ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
X Ray ◽  
Star Forming ◽  
Sky Survey ◽  
The Galaxy ◽  
Galaxy Population

In this work we use the property that, on average, star formation rate increases with redshift for objects with the same mass – the so called galaxy main sequence – to measure the redshift of galaxy clusters. We use the fact that the general galaxy population forms both a quenched and a star-forming sequence, and we locate these ridges in the SFR–M⋆ plane with galaxies taken from the Sloan Digital Sky Survey in discrete redshift bins. We fitted the evolution of the galaxy main sequence with redshift using a new method and then subsequently apply our method to a suite of X-ray selected galaxy clusters in an attempt to create a new distance measurement to clusters based on their galaxy main sequence. We demonstrate that although it is possible in several galaxy clusters to measure the main sequences, the derived distance and redshift from our galaxy main sequence fitting technique has an accuracy of σz = ±0.017 ⋅ (z + 1) and is only accurate up to z ≈ 0.2.

scholarly journals Effect of the environment on star formation activity and stellar mass for star-forming galaxies in the COSMOS field

2020 ◽  
Vol 499 (1) ◽  
pp. 948-956
Author(s):  
S M Randriamampandry ◽  
M Vaccari ◽  
K M Hess
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Star Forming ◽  
Galaxy Environment ◽  
Stellar Masses ◽  
The Relationship

ABSTRACT We investigate the relationship between the environment and the galaxy main sequence (the relationship between stellar mass and star formation rate), as well as the relationship between the environment and radio luminosity ($P_{\rm 1.4\, GHz}$), to shed new light on the effects of the environment on galaxies. We use the VLA-COSMOS 3-GHz catalogue, which consists of star-forming galaxies and quiescent galaxies (active galactic nuclei) in three different environments (field, filament, cluster) and for three different galaxy types (satellite, central, isolated). We perform for the first time a comparative analysis of the distribution of star-forming galaxies with respect to the main-sequence consensus region from the literature, taking into account galaxy environment and using radio observations at 0.1 ≤ z ≤ 1.2. Our results corroborate that the star formation rate is declining with cosmic time, which is consistent with the literature. We find that the slope of the main sequence for different z and M* bins is shallower than the main-sequence consensus, with a gradual evolution towards higher redshift bins, irrespective of environment. We see no trends for star formation rate in either environment or galaxy type, given the large errors. In addition, we note that the environment does not seem to be the cause of the flattening of the main sequence at high stellar masses for our sample.

scholarly journals ATLASGAL, the APEX Telescope Large Area Survey of the Galaxy

2009 ◽  
Vol 5 (H15) ◽  
pp. 780-780
Author(s):  
F. Schuller ◽  
K. M. Menten ◽  
F. Wyrowski ◽  
H. Beuther ◽  
S. Bontemps ◽  
...  
Keyword(s):  
Galactic Plane ◽  
High Mass ◽  
Current Status ◽  
Continuum Emission ◽  
Mass Star ◽  
Large Area ◽  
Submillimeter Wavelengths ◽  
The Galaxy ◽  
First Results ◽  
Area Survey

AbstractSubmillimeter continuum emission traces high molecular column densities and, thus, dense cloud regions in which new stars are forming. Surveys of the Galactic plane in such emission have the potential of delivering an unbiased view of high-mass star formation throughout the Milky Way. Here we present the scope, current status and first results of ATLASGAL, an ongoing survey of the Galactic plane using the Large APEX Bolometer Camera (LABOCA) on the Atacama Pathfinder Experiment (APEX) telescope at the Chajnantor plateau in Chile. Aimed at mapping 360 square degrees at 870 μm, with a uniform sensitivity of 50 mJy/beam, this survey will provide the first unbiased sample of cold dusty clumps in the Galaxy at submillimeter wavelengths. These will be targets for molecular line follow-up observations and high resolution studies with ALMA and the EVLA.

scholarly journals The Diffuse Ionised Gas in NGC 4449

1998 ◽  
Vol 15 (1) ◽  
pp. 103-105 ◽  
Author(s):  
C. Muñoz-Tuñón ◽  
O. Fuentes-Masip ◽  
H. O. Castañeda
Keyword(s):  
Large Population ◽  
Star Forming ◽  
Star Forming Regions ◽  
La Palma ◽  
Total Luminosity ◽  
Spatial Coverage ◽  
The Galaxy ◽  
Uv Photons ◽  
Set Up ◽  
The Individual

AbstractIt is now well established that there is a diffuse ionised medium which extends far beyond the disks of spirals. The mechanism responsible for the ionisation is still an issue of debate, and the method of measuring the total luminosity, independently of the observational set-up, has to be defined. Here we analyse the case of the Magellanic irregular NGC 4449, using Fabry–Perot bidimensional mapping of the Hα emission line, at the 4·2 m William Herschel Telescope (WHT) telescope on La Palma, Canary Islands. The total spatial coverage of 80×80 arcsec2 allows most of the star forming regions to be sampled at 0·26 arcsec/pixel spatial resolution. Using 3D spectroscopy, it is possible to define the individual star-forming regions and to produce a luminosity versus size diagram. This can be used to estimate directly the number of photons leaking out from those regions exceeding the thickness of the galactic disc. In the case of NGC 4449 it is shown that the large population of GEHRs can be the source of UV photons ionising the diffuse ionised gas (DIG) of the galaxy, and the logL–R diagram can be used to quantify the number of photons leaking out of the material surrounding the star forming regions. In the case of NGC 4449 it is found that 54% of the total luminosity of the giant star-forming regions is lost to the DIG. This implies a contribution of 3·12×1040 erg s−1 (1 erg s−1 = 10−7 J s−1) which amounts to 30% of the galaxy total Hα luminosity.

scholarly journals Galaxies in most dense environments at redshift 1.4

2012 ◽  
Vol 8 (S295) ◽  
pp. 61-61
Author(s):  
V. Strazzullo
Keyword(s):  
Galaxy Evolution ◽  
Cosmic Time ◽  
Active Galaxy ◽  
Cluster Core ◽  
Host Galaxy ◽  
Early Type ◽  
X Ray ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
Massive Cluster

AbstractAt a cosmic time when galaxy clusters start showing evidence of a still active galaxy population, the X-ray luminous, massive cluster XMMU J2235-2557 at z=1.39, already hosts massive, quiescent, early-type galaxies on a tight red sequence dominating the cluster core. XMMU J2235-2557 is among the most massive of the very distant clusters, which may explain the evolved status of the system itself, and of its host galaxy populations. It remains a unique laboratory to observe environment-biased galaxy evolution already 9 billion years ago.

scholarly journals X-raying winds in distant quasars: The first high-redshift wind duty cycle

2020 ◽  
Vol 638 ◽  
pp. A136
Author(s):  
E. Bertola ◽  
M. Dadina ◽  
M. Cappi ◽  
C. Vignali ◽  
G. Chartas ◽  
...  
Keyword(s):  
Duty Cycle ◽  
High Redshift ◽  
Cosmic Time ◽  
Theoretical Models ◽  
Host Galaxy ◽  
Time Interval ◽  
Absorption Column ◽  
X Ray ◽  
Spatially Resolved ◽  
First Time

Aims. Theoretical models of wind-driven feedback from active galactic nuclei (AGN) often identify ultra-fast outflows as being the main agent in the generation of galaxy-sized outflows, which are possibly the main actors in establishing so-called AGN-galaxy co-evolution. Ultra-fast outflows are well characterized in local AGN but much less is known in quasars at the cosmic time when star formation and AGN activity peaked (z ≃ 1–3). It is therefore necessary to search for evidence of ultra-fast outflows in high-z sources to test wind-driven AGN feedback models. Methods. Here we present a study of Q2237+030, the Einstein Cross, a quadruply-imaged radio-quiet lensed quasar located at z = 1.695. We performed a systematic and comprehensive temporally and spatially resolved X-ray spectral analysis of all the available Chandra and XMM-Newton data (as of September 2019). Results. We find clear evidence for spectral variability, possibly due to absorption column density (or covering fraction) variability intrinsic to the source. For the first time in this quasar, we detect a fast X-ray wind outflowing at vout ≃ 0.1c that would be powerful enough (Ėkin ≃ 0.1 Lbol) to significantly affect the evolution of the host galaxy. We report also on the possible presence of an even faster component of the wind (vout ∼ 0.5c). For the first time in a high-z quasar, given the large sample and long time interval spanned by the analyzed X-ray data, we are able to roughly estimate the wind duty cycle as ≃0.46 (0.31) at 90% (95%) confidence level. Finally, we also confirm the presence of a Fe Kα emission line with variable energy, which we discuss in the light of microlensing effects as well as considering our findings on the source.

scholarly journals The X-ray and radio activity of typical and luminous Ly α emitters from z ∼ 2 to z ∼ 6: evidence for a diverse, evolving population

2020 ◽  
Vol 493 (3) ◽  
pp. 3341-3362 ◽  
Author(s):  
João Calhau ◽  
David Sobral ◽  
Sérgio Santos ◽  
Jorryt Matthee ◽  
Ana Paulino-Afonso ◽  
...  
Keyword(s):  
Black Hole ◽  
Formation Rate ◽  
Cosmic Time ◽  
X Rays ◽  
Growth Ratio ◽  
X Ray ◽  
Star Forming ◽  
Black Hole Accretion ◽  
Different Populations ◽  
Hole Accretion

ABSTRACT Despite recent progress in understanding Ly α emitters (LAEs), relatively little is known regarding their typical black hole activity across cosmic time. Here, we study the X-ray and radio properties of ∼4000 LAEs at 2.2 < $z$ < 6 from the SC4K survey in the COSMOS field. We detect 254 ($6.8{\rm{ per\ cent}} \pm 0.4{\rm{ per\ cent}}$) LAEs individually in the X-rays (S/N > 3) with an average luminosity of $\rm 10^{44.31\pm 0.01}\, erg\, s^{-1}$ and average black hole accretion rate (BHAR) of $\rm 0.72 \pm 0.01$ M⊙ yr−1, consistent with moderate to high accreting active galactic neuclei (AGNs). We detect 120 sources in deep radio data (radio AGN fraction of $3.2{\rm{ per\ cent}} \pm 0.3{\rm{ per\ cent}}$). The global AGN fraction ($\rm 8.6{\rm{ per\ cent}} \pm 0.4{\rm{ per\ cent}}$) rises with Ly α luminosity and declines with increasing redshift. For X-ray-detected LAEs, Ly α luminosities correlate with the BHARs, suggesting that Ly α luminosity becomes a BHAR indicator. Most LAEs ($93.1{\rm{ per\ cent}} \pm 0.6{\rm{ per\ cent}}$) at 2 < $z$ < 6 have no detectable X-ray emission (BHARs < 0.017 M⊙ yr−1). The median star formation rate (SFR) of star-forming LAEs from Ly α and radio luminosities is $7.6^{+6.6}_{-2.8}$ M⊙ yr−1. The black hole to galaxy growth ratio (BHAR/SFR) for LAEs is <0.0022, consistent with typical star-forming galaxies and the local BHAR/SFR relation. We conclude that LAEs at 2 < $z$ < 6 include two different populations: an AGN population, where Ly α luminosity traces BHAR, and another with low SFRs which remain undetected in even the deepest X-ray stacks but is detected in the radio stacks.

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