scholarly journals The post-Herschel view of intrinsic AGN emission: constructing templates for galaxy and AGN emission at IR wavelengths

2021 ◽  
Vol 503 (2) ◽  
pp. 2598-2621
Author(s):  
E Bernhard ◽  
C Tadhunter ◽  
J R Mullaney ◽  
L P Grimmett ◽  
D J Rosario ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Spectral Energy Distribution ◽  
Far Infrared ◽  
Infrared Emission ◽  
Host Galaxy ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Star Forming ◽  
Galaxy Formation And Evolution ◽  
Infrared Diagnostics

ABSTRACT Measuring the star-forming properties of active galactic nucleus (AGN) hosts is key to our understanding of galaxy formation and evolution. However, this topic remains debated, partly due to the difficulties in separating the infrared (i.e. 1–1000 ${\rm \mu m}$) emission into AGN and star-forming components. Taking advantage of archival far-infrared data from Herschel, we present a new set of AGN and galaxy infrared templates and introduce the spectral energy distribution fitting code iragnsep. Both can be used to measure infrared host galaxy properties, free of AGN contamination. To build these, we used a sample of 100 local (z < 0.3), low-to-high luminosity AGNs (i.e. Lbol$\ \sim \ 10^{42-46}$ erg s−1), selected from the 105-month Swift–BAT X-ray survey, which have archival Spitzer–IRS spectra and Herschel photometry. We first built a set of seven galaxy templates using a sample of 55 star-forming galaxies selected via infrared diagnostics. Using these templates, combined with a flexible model for the AGN contribution, we extracted the intrinsic infrared emission of our AGN sample. We further demonstrate that we can reduce the diversity in the intrinsic shapes of AGN spectral energy distributions down to a set of three AGN templates, of which two represent AGN continuum, and one represents silicate emission. Our results indicate that, on average, the contribution of AGNs to the far-infrared (λ ≳ 50 ${\rm \mu m}$) is not as high as suggested by some recent work. We further show that the need for two infrared AGN continuum templates could be related to nuclear obscuration, where one of our templates appears dominated by the emission of the extended polar dust.

scholarly journals Towards a census of high-redshift dusty galaxies with Herschel

2018 ◽  
Vol 614 ◽  
pp. A33 ◽  
Author(s):  
D. Donevski ◽  
V. Buat ◽  
F. Boone ◽  
C. Pappalardo ◽  
M. Bethermin ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Far Infrared ◽  
Virgo Cluster ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Redshift Distribution ◽  
Star Forming

Context. Over the last decade a large number of dusty star-forming galaxies has been discovered up to redshift z = 2 − 3 and recent studies have attempted to push the highly confused Herschel SPIRE surveys beyond that distance. To search for z ≥ 4 galaxies they often consider the sources with fluxes rising from 250 μm to 500 μm (so-called “500 μm-risers”). Herschel surveys offer a unique opportunity to efficiently select a large number of these rare objects, and thus gain insight into the prodigious star-forming activity that takes place in the very distant Universe. Aims. We aim to implement a novel method to obtain a statistical sample of 500 μm-risers and fully evaluate our selection inspecting different models of galaxy evolution. Methods. We consider one of the largest and deepest Herschel surveys, the Herschel Virgo Cluster Survey. We develop a novel selection algorithm which links the source extraction and spectral energy distribution fitting. To fully quantify selection biases we make end-to-end simulations including clustering and lensing. Results. We select 133 500 μm-risers over 55 deg2, imposing the criteria: S500 > S350 > S250, S250 > 13.2 mJy and S500 > 30 mJy. Differential number counts are in fairly good agreement with models, displaying a better match than other existing samples. The estimated fraction of strongly lensed sources is 24+6-5% based on models. Conclusions. We present the faintest sample of 500 μm-risers down to S250 = 13.2 mJy. We show that noise and strong lensing have an important impact on measured counts and redshift distribution of selected sources. We estimate the flux-corrected star formation rate density at 4 < z < 5 with the 500 μm-risers and find it to be close to the total value measured in far-infrared. This indicates that colour selection is not a limiting effect to search for the most massive, dusty z > 4 sources.

scholarly journals Multiwavelength radio observations of a brightest cluster galaxy at z = 1.71: detection of a modest active galactic nucleus and evidence for extended star formation

2019 ◽  
Vol 487 (1) ◽  
pp. 1210-1217 ◽  
Author(s):  
Ariane Trudeau ◽  
Tracy Webb ◽  
Julie Hlavacek-Larrondo ◽  
Allison Noble ◽  
Marie-Lou Gendron-Marsolais ◽  
...  
Keyword(s):  
Star Formation ◽  
Active Galactic Nucleus ◽  
Spectral Energy Distribution ◽  
Galaxy Cluster ◽  
Far Infrared ◽  
Infrared Emission ◽  
Spectral Energy ◽  
Radio Observations ◽  
Cluster Galaxy ◽  
Star Forming

ABSTRACT We present deep, multiwavelength radio observations of SpARCS104922.6 + 564032.5, a z = 1.71 galaxy cluster with a starbursting core. Observations were made with the Karl G. Jansky Very Large Array (JVLA) in three bands: 1–2 GHz, 4–8 GHz, and 8–12 GHz. We detect a radio source coincident with the brightest cluster galaxy (BCG) that has a spectral index of α = 0.44 ± 0.29 and is indicative of emission from an active galactic nucleus. The radio luminosity is consistent with the average luminosity of the lower redshift BCG sample, but the flux densities are 6σ below the predicted values of the star-forming spectral energy distribution based on far infrared data. Our new fit fails to simultaneously describe the far infrared and radio fluxes. This, coupled with the fact that no other bright source is detected in the vicinity of the BCG implies that the star formation region, traced by the infrared emission, is extended or clumpy and not located directly within the BCG. Thus, we suggest that the star-forming core might not be driven by a single major wet merger, but rather by several smaller galaxies stripped of their gas or by a displaced cooling flow, although more data are needed to confirm any of those scenarios.

scholarly journals Far-infrared star formation rates of six GRB host galaxies with ALMA

2020 ◽  
Vol 496 (4) ◽  
pp. 4405-4419
Author(s):  
Tiger Yu-Yang Hsiao ◽  
Tetsuya Hashimoto ◽  
Jia-Yuan Chang ◽  
Tomotsugu Goto ◽  
Seong Jin Kim ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Thermal Emission ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Far Infrared ◽  
Host Galaxy ◽  
Spectral Energy ◽  
Host Galaxies ◽  
Distribution Fitting

ABSTRACT Gamma-ray bursts (GRBs) can be a promising tracer of cosmic star formation rate history (CSFRH). In order to reveal the CSFRH using GRBs, it is important to understand whether they are biased tracers or not. For this purpose, it is crucial to understand properties of GRB host galaxies, in comparison to field galaxies. In this work, we report ALMA far-infrared (FIR) observations of six z ∼ 2 IR-bright GRB host galaxies, which are selected for the brightness in IR. Among them, four host galaxies are detected for the first time in the rest-frame FIR. In addition to the ALMA data, we collected multiwavelength data from previous studies for the six GRB host galaxies. Spectral energy distribution fitting analyses were performed with cigale to investigate physical properties of the host galaxies, and to test whether active galactic nucleus (AGN) and radio components are required or not. Our results indicate that the best-fitting templates of five GRB host galaxies do not require an AGN component, suggesting the absence of AGNs. One GRB host galaxy, 080207, shows a very small AGN contribution. While derived stellar masses of the three host galaxies are mostly consistent with those in previous studies, interestingly the value of star formation rates (SFRs) of all six GRB hosts are inconsistent with previous studies. Our results indicate the importance of rest-frame FIR observations to correctly estimate SFRs by covering thermal emission from cold dust heated by star formation.

scholarly journals The effects of star formation history in the SFR–M* relation of H ii galaxies

2020 ◽  
Vol 500 (3) ◽  
pp. 3240-3253
Author(s):  
Amanda R Lopes ◽  
Eduardo Telles ◽  
Jorge Melnick
Keyword(s):  
Star Formation ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Star Formation History ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Good Tool ◽  
Star Forming ◽  
Additional Information ◽  
Star Formation Histories

ABSTRACT We discuss the implications of assuming different star formation histories (SFH) in the relation between star formation rate (SFR) and mass derived by the spectral energy distribution fitting (SED). Our analysis focuses on a sample of H ii galaxies, dwarf starburst galaxies spectroscopically selected through their strong narrow emission lines in SDSS DR13 at z &lt; 0.4, cross-matched with photometric catalogues from GALEX, SDSS, UKIDSS, and WISE. We modelled and fitted the SEDs with the code CIGALE adopting different descriptions of SFH. By adding information from different independent studies, we find that H ii galaxies are best described by episodic SFHs including an old (10 Gyr), an intermediate age (100−1000 Myr) and a recent population with ages &lt; 10 Myr. H ii galaxies agree with the SFR−M* relation from local star-forming galaxies, and only lie above such relation when the current SFR is adopted as opposed to the average over the entire SFH. The SFR−M* demonstrated not to be a good tool to provide additional information about the SFH of H ii galaxies, as different SFH present a similar behaviour with a spread of &lt;0.1 dex.

scholarly journals The MUSE Hubble Ultra Deep Field Survey

2018 ◽  
Vol 617 ◽  
pp. A62 ◽  
Author(s):  
Anna Feltre ◽  
Roland Bacon ◽  
Laurence Tresse ◽  
Hayley Finley ◽  
David Carton ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Gas Content ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Space Telescope ◽  
Star Forming ◽  
Neutral Gas ◽  
Near Ultraviolet ◽  
Hubble Ultra Deep Field ◽  
Stellar Masses

The physical origin of the near-ultraviolet Mg II emission remains an underexplored domain, unlike more typical emission lines that are detected in the spectra of star-forming galaxies. We explore the nebular and physical properties of a sample of 381 galaxies between 0.70 < z < 2.34 drawn from the MUSE Hubble Ultra Deep Survey. The spectra of these galaxies show a wide variety of profiles of the Mg II λλ2796, 2803 resonant doublet, from absorption to emission. We present a study on the main drivers for the detection of Mg II emission in galaxy spectra. By exploiting photoionization models, we verified that the emission-line ratios observed in galaxies with Mg II in emission are consistent with nebular emission from HII regions. From a simultaneous analysis of MUSE spectra and ancillary Hubble Space Telescope information through spectral energy distribution fitting, we find that galaxies with Mg II in emission have lower stellar masses, smaller sizes, bluer spectral slopes, and lower optical depth than those with absorption. This leads us to suggest that Mg II emission is a potential tracer of physical conditions that are not merely related to those of the ionized gas. We show that these differences in Mg II emission and absorption can be explained in terms of a higher dust and neutral gas content in the interstellar medium (ISM) of galaxies showing Mg II in absorption, which confirms the extreme sensitivity of Mg II to the presence of the neutral ISM. We conclude with an analogy between the Mg II doublet and the Ly α line that lies in their resonant nature. Further investigations with current and future facilities, including the James Webb Space Telescope, are promising because the detection of Mg II emission and its potential connection with Lyα could provide new insights into the ISM content in the early Universe.

scholarly journals A machine-learning approach for identifying the counterparts of submillimetre galaxies and applications to the GOODS-North field

2019 ◽  
Vol 489 (2) ◽  
pp. 1770-1786 ◽  
Author(s):  
Ruihan Henry Liu ◽  
Ryley Hill ◽  
Douglas Scott ◽  
Omar Almaini ◽  
Fangxia An ◽  
...  
Keyword(s):  
Neural Network ◽  
Machine Learning ◽  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Computational Cost ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Star Forming ◽  
Trained Neural Network ◽  
Validation Tests

ABSTRACT Identifying the counterparts of submillimetre (submm) galaxies (SMGs) in multiwavelength images is a critical step towards building accurate models of the evolution of strongly star-forming galaxies in the early Universe. However, obtaining a statistically significant sample of robust associations is very challenging due to the poor angular resolution of single-dish submm facilities. Recently, a large sample of single-dish-detected SMGs in the UKIDSS UDS field, a subset of the SCUBA-2 Cosmology Legacy Survey (S2CLS), was followed up with the Atacama Large Millimeter/submillimeter Array (ALMA), which has provided the resolution necessary for identification in optical and near-infrared images. We use this ALMA sample to develop a training set suitable for machine-learning (ML) algorithms to determine how to identify SMG counterparts in multiwavelength images, using a combination of magnitudes and other derived features. We test several ML algorithms and find that a deep neural network performs the best, accurately identifying 85 per cent of the ALMA-detected optical SMG counterparts in our cross-validation tests. When we carefully tune traditional colour-cut methods, we find that the improvement in using machine learning is modest (about 5 per cent), but importantly it comes at little additional computational cost. We apply our trained neural network to the GOODS-North field, which also has single-dish submm observations from the S2CLS and deep multiwavelength data but little high-resolution interferometric submm imaging, and we find that we are able to classify SMG counterparts for 36/67 of the single-dish submm sources. We discuss future improvements to our ML approach, including combining ML with spectral energy distribution fitting techniques and using longer wavelength data as additional features.

scholarly journals Timing the earliest quenching events with a robust sample of massive quiescent galaxies at 2 < z < 5

2020 ◽  
Vol 496 (1) ◽  
pp. 695-707 ◽  
Author(s):  
A C Carnall ◽  
S Walker ◽  
R J McLure ◽  
J S Dunlop ◽  
D J McLeod ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Selection Criteria ◽  
Spectral Energy Distribution ◽  
Photometric Data ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Star Forming ◽  
Photometric Redshift ◽  
The Times ◽  
Lower Redshift

ABSTRACT We present a sample of 151 massive (M* &gt; 1010 M⊙) quiescent galaxies at 2 &lt; z &lt; 5, based on a sophisticated Bayesian spectral energy distribution fitting analysis of the CANDELS UDS and GOODS-South fields. Our sample includes a robust sub-sample of 61 objects for which we confidently exclude low-redshift and star-forming solutions. We identify 10 robust objects at z &gt; 3, of which 2 are at z &gt; 4. We report formation redshifts, demonstrating that the oldest objects formed at z &gt; 6; however, individual ages from our photometric data have significant uncertainties, typically ∼0.5 Gyr. We demonstrate that the UVJ colours of the quiescent population evolve with redshift at z &gt; 3, becoming bluer and more similar to post-starburst galaxies at lower redshift. Based upon this, we construct a model for the time evolution of quiescent galaxy UVJ colours, concluding that the oldest objects are consistent with forming the bulk of their stellar mass at z ∼ 6–7 and quenching at z ∼ 5. We report spectroscopic redshifts for two of our objects at z = 3.440 and 3.396, which exhibit extremely weak Ly α emission in ultra-deep VANDELS spectra. We calculate star formation rates based on these line fluxes, finding that these galaxies are consistent with our quiescent selection criteria, provided their Ly α escape fractions are &gt;3 and &gt;10 per cent, respectively. We finally report that our highest redshift robust object exhibits a continuum break at λ ∼ 7000 Å in a spectrum from VUDS, consistent with our photometric redshift of $z_\mathrm{phot}=4.72^{+0.06}_{-0.04}$. If confirmed as quiescent, this object would be the highest redshift known quiescent galaxy. To obtain stronger constraints on the times of the earliest quenching events, high-SNR spectroscopy must be extended to z ≳ 3 quiescent objects.

scholarly journals SUPER

2018 ◽  
Vol 620 ◽  
pp. A82 ◽  
Author(s):  
C. Circosta ◽  
V. Mainieri ◽  
P. Padovani ◽  
G. Lanzuisi ◽  
M. Salvato ◽  
...  
Keyword(s):  
Star Formation ◽  
Adaptive Optics ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Host Galaxy ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
X Ray ◽  
Narrow Component ◽  
The Impact

Theoretical models of galaxy formation suggest that the presence of an active galactic nucleus (AGN) is required to regulate the growth of its host galaxy through feedback mechanisms, produced by, for example, AGN-driven outflows. Although many observational studies have revealed that such outflows are common both at low and high redshift, a comprehensive picture is still missing. In particular, the peak epoch of galaxy assembly (1 <  z <  3) has been poorly explored so far, and current observations in this redshift range are mostly limited to targets with high chances to be in an outflowing phase. This paper introduces SUPER (a SINFONI Survey for Unveiling the Physics and Effect of Radiative feedback), an ongoing ESO’s VLT/SINFONI Large Programme. SUPER will perform the first systematic investigation of ionized outflows in a sizeable and blindly-selected sample of 39 X-ray AGN at z ∼ 2, which reaches high spatial resolutions (∼2 kpc) thanks to the adaptive optics-assisted IFS observations. The outflow morphology and star formation in the host galaxy will be mapped through the broad component of [O III]λ5007 and the narrow component of Hα emission lines. The main aim of our survey is to infer the impact of outflows on the on-going star formation and to link the outflow properties to a number of AGN and host galaxy properties. We describe here the survey characteristics and goals, as well as the selection of the target sample. Moreover, we present a full characterization of its multi-wavelength properties: we measure, via spectral energy distribution fitting of UV-to-FIR photometry, stellar masses (4 × 109 − 2 × 1011 M⊙), star formation rates (25 − 680 M⊙ yr−1) and AGN bolometric luminosities (2 × 1044 − 8 × 1047 erg s−1), along with obscuring column densities (up to 2 × 1024 cm−2) and luminosities in the hard 2 − 10 keV band (2 × 1043 − 6 × 1045 erg s−1) derived through X-ray spectral analysis. Finally, we classify our AGN as jetted or non-jetted according to their radio and FIR emission.

scholarly journals The AGN contribution to the UV–FIR luminosities of interacting galaxies and its role in identifying the main sequence

2020 ◽  
Vol 499 (3) ◽  
pp. 4325-4369
Author(s):  
Andrés F Ramos Padilla ◽  
M L N Ashby ◽  
Howard A Smith ◽  
Juan R Martínez-Galarza ◽  
Aliza G Beverage ◽  
...  
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Far Infrared ◽  
Stellar Mass ◽  
Spectral Energy ◽  
Star Forming ◽  
Nuclear Regions ◽  
The Impact

ABSTRACT Emission from active galactic nuclei (AGNs) is known to play an important role in the evolution of many galaxies including luminous and ultraluminous systems (U/LIRGs), as well as merging systems. However, the extent, duration, and exact effects of its influence are still imperfectly understood. To assess the impact of AGNs on interacting systems, we present a spectral energy distribution (SED) analysis of a sample of 189 nearby galaxies. We gather and systematically re-reduce archival broad-band imaging mosaics from the ultraviolet to the far-infrared using data from GALEX, SDSS, 2MASS, IRAS, WISE, Spitzer, and Herschel. We use spectroscopy from Spitzer/IRS to obtain fluxes from fine-structure lines that trace star formation and AGN activity. Utilizing the SED modelling and fitting tool cigale, we derive the physical conditions of the interstellar medium, both in star-forming regions and in nuclear regions dominated by the AGN in these galaxies. We investigate how the star formation rates (SFRs) and the fractional AGN contributions (fAGN) depend on stellar mass, galaxy type, and merger stage. We find that luminous galaxies more massive than about $10^{10} \,\rm {M}_{*}$ are likely to deviate significantly from the conventional galaxy main-sequence relation. Interestingly, infrared AGN luminosity and stellar mass in this set of objects are much tighter than SFR and stellar mass. We find that buried AGNs may occupy a locus between bright starbursts and pure AGNs in the fAGN–[Ne v]/[Ne ii] plane. We identify a modest correlation between fAGN and mergers in their later stages.

Sign in / Sign up

Export Citation Format

Share Document