Nearby galaxies offer unique laboratories allowing multi-wavelength spatially resolved studies of the interstellar medium, star formation and nuclear activity across a broad range of physical ...conditions. In particular, detailed studies of individual local luminous infrared galaxies (LIRGs) are crucial for gaining a better understanding of these processes and for developing and testing models that are used to explain statistical studies of large populations of such galaxies at high redshift for which it is currently impossible to reach a sufficient physical resolution. Here, we provide an overview of the impact of spatially resolved infrared, sub-millimetre and radio observations in the study of the interstellar medium, star formation and active galactic nuclei as well as their interplay in local LIRGs. We also present an overview of the modelling of their spectral energy distributions using state-of-the-art radiative transfer codes. These contribute necessary and powerful ‘workhorse’ tools for the study of LIRGs (and their more luminous counterparts) at higher redshifts which are unresolved in observations. We describe how spatially-resolved time-domain observations have recently opened a new window to study the nuclear activity in LIRGs. We describe in detail the observational characteristics of Arp 299 which is one of the best studied local LIRGs and exemplifies the power of the combination of time-domain and high-resolution observations at infrared to radio wavelengths together with radiative transfer modelling used to explain the spectral energy distributions of its different components. We summarise the previous achievements obtained using high-spatial resolution observations and provide an outlook into what we can expect to achieve with future facilities.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
Observations have found black holes spanning 10 orders of magnitude in mass across most of cosmic history. The Kerr black hole solution is, however, provisional as its behavior at infinity ...is incompatible with an expanding universe. Black hole models with realistic behavior at infinity predict that the gravitating mass of a black hole can increase with the expansion of the universe independently of accretion or mergers, in a manner that depends on the black hole’s interior solution. We test this prediction by considering the growth of supermassive black holes in elliptical galaxies over 0 <
z
≲ 2.5. We find evidence for cosmologically coupled mass growth among these black holes, with zero cosmological coupling excluded at 99.98% confidence. The redshift dependence of the mass growth implies that, at
z
≲ 7, black holes contribute an effectively constant cosmological energy density to Friedmann’s equations. The continuity equation then requires that black holes contribute cosmologically as vacuum energy. We further show that black hole production from the cosmic star formation history gives the value of Ω
Λ
measured by Planck while being consistent with constraints from massive compact halo objects. We thus propose that stellar remnant black holes are the astrophysical origin of dark energy, explaining the onset of accelerating expansion at
z
∼ 0.7.
Abstract
The assembly of stellar and supermassive black hole (SMBH) mass in elliptical galaxies since
z
∼ 1 can help to diagnose the origins of locally observed correlations between SMBH mass and ...stellar mass. We therefore construct three samples of elliptical galaxies, one at
z
∼ 0 and two at 0.7 ≲
z
≲ 2.5, and quantify their relative positions in the
M
BH
−
M
*
plane. Using a Bayesian analysis framework, we find evidence for translational offsets in both stellar mass and SMBH mass between the local sample and both higher-redshift samples. The offsets in stellar mass are small, and consistent with measurement bias, but the offsets in SMBH mass are much larger, reaching a factor of 7 between
z
∼ 1 and
z
∼ 0. The magnitude of the SMBH offset may also depend on redshift, reaching a factor of ∼20 at
z
∼ 2. The result is robust against variation in the high- and low-redshift samples and changes in the analysis approach. The magnitude and redshift evolution of the offset are challenging to explain in terms of selection and measurement biases. We conclude that either there is a physical mechanism that preferentially grows SMBHs in elliptical galaxies at
z
≲ 2, or that selection and measurement biases are both underestimated, and depend on redshift.
ABSTRACT
The validity of the unified active galactic nuclei (AGNs) model has been challenged in the last decade, especially when different types of AGNs are considered to only differ in the viewing ...angle to the torus. We aim to assess the importance of the viewing angle in classifying different types of Seyfert galaxies in spectral energy distribution (SED) modelling. We retrieve photometric data from publicly available astronomical data bases: CDS and NED, to model SEDs with x-cigale in a sample of 13 173 Seyfert galaxies located at redshift range from z = 0 to 3.5, with a median redshift of z ≈ 0.2. We assess whether the estimated viewing angle from the SED models reflects different Seyfert classifications. Two AGN models with either a smooth or clumpy torus structure are adopted in this paper. We find that the viewing angle in Type-1 AGNs is better constrained than in Type-2 AGNs. Limiting the viewing angles representing these two types of AGNs does not affect the physical parameter estimates such as star formation rate (SFR) or AGN fractional contribution (fAGN). In addition, the viewing angle is not the most discriminating physical parameter to differentiate Seyfert types. We suggest that the observed and intrinsic AGN disc luminosity can (i) be used in z < 0.5 studies to distinguish between Type-1 and Type-2 AGNs, and (ii) explain the probable evolutionary path between these AGN types. Finally, we propose the use of x-cigale for AGN galaxy classification tasks. All data from the 13 173 SED fits are available at Zenodo1.
We present observations of NGC 1068 covering the 19.7-53.0 m wavelength range using FORCAST and HAWC+ on board SOFIA. Using these observations, high-angular-resolution infrared (IR) and submillimeter ...observations, we find an observational turnover of the torus emission in the 30-40 m wavelength range with a characteristic temperature of 70-100 K. This component is clearly different from the diffuse extended emission in the narrow line and star formation regions at 10-100 m within the central 700 pc. We compute 2.2-432 m 2D images using the best inferred clumpy torus model based on several nuclear spectral energy distribution (SED) coverages. We find that when 1-20 m SED is used, the inferred result gives a small torus size (<4 pc radius) and a steep radial dust distribution. The computed torus using the 1-432 m SED provides comparable torus sizes, pc radius, and morphology to the recently resolved 432 m Atacama Large Millimeter Array observations. This result indicates that the 1-20 m wavelength range is not able to probe the full extent of the torus. The characterization of the turnover emission of the torus using the 30-60 m wavelength range is sensitive to the detection of cold dust in the torus. The morphology of the dust emission in our 2D image at 432 m is spatially coincident with the cloud distribution, while the morphology of the emission in the 1-20 m wavelength range shows an elongated morphology perpendicular to the cloud distribution. We find that our 2D clumpy torus image at 12 m can produce comparable results to those observed using IR interferometry.
We present new subarcsecond-resolution Karl G. Jansky Very Large Array (VLA) imaging at 10 GHz of 155 ultraluminous (Lbol ∼ 1011.7-1014.2 L ) and heavily obscured quasars with redshifts z ∼ 0.4-3. ...The sample was selected to have extremely red mid-infrared-optical color ratios based on data from the Wide-Field Infrared Survey Explorer (WISE) along with a detection of bright, unresolved radio emission from the NRAO VLA Sky Survey (NVSS) or Faint Images of the Radio Sky at Twenty cm Survey. Our high-resolution VLA observations have revealed that the majority of the sources in our sample (93 out of 155) are compact on angular scales <0 2 (≤1.7 kpc at z ∼ 2). The radio luminosities, linear extents, and lobe pressures of our sources are similar to young radio active galactic nuclei (e.g., gigahertz-peaked spectrum GPS and compact steep-spectrum CSS sources), but their space density is considerably lower. Application of a simple adiabatic lobe expansion model suggests relatively young dynamical ages (∼104-7 yr), relatively high ambient ISM densities (∼1-104 cm−3), and modest lobe expansion speeds (∼30-10,000 km s−1). Thus, we find our sources to be consistent with a population of newly triggered, young jets caught in a unique evolutionary stage in which they still reside within the dense gas reservoirs of their hosts. Based on their radio luminosity function and dynamical ages, we estimate that only ∼20% of classical large-scale FR I/II radio galaxies could have evolved directly from these objects. We speculate that the WISE-NVSS sources might first become GPS or CSS sources, of which some might ultimately evolve into larger radio galaxies.
Abstract
Nuclear starbursts and active galactic nucleus (AGN) activity are the main heating processes in luminous infrared galaxies (LIRGs) and their relationship is fundamental to understand galaxy ...evolution. In this paper, we study the star formation and AGN activity of a sample of 11 local LIRGs imaged with subarcsecond angular resolution at radio (8.4 GHz) and near-infrared (2.2 μm) wavelengths. This allows us to characterize the central kpc of these galaxies with a spatial resolution of ≃100 pc. In general, we find a good spatial correlation between the radio and the near-IR emission, although radio emission tends to be more concentrated in the nuclear regions. Additionally, we use an Markov Chain Monte Carlo code to model their multiwavelength spectral energy distribution (SED) using template libraries of starburst, AGN and spheroidal/cirrus models, determining the luminosity contribution of each component, and finding that all sources in our sample are starburst-dominated, except for NGC 6926 with an AGN contribution of ≃64 per cent. Our sources show high star formation rates (40–167 M⊙ yr−1), supernova rates (0.4–2.0 SN yr−1) and similar starburst ages (13–29 Myr), except for the young starburst (9 Myr) in NGC 6926. A comparison of our derived star-forming parameters with estimates obtained from different IR and radio tracers shows an overall consistency among the different star formation tracers. AGN tracers based on mid-IR, high-ionization line ratios also show an overall agreement with our SED model fit estimates for the AGN. Finally, we use our wide-band Very Large Array observations to determine pixel-by-pixel radio spectral indices for all galaxies in our sample, finding a typical median value (α ≃ −0.8) for synchrotron-powered LIRGs.
We present optical to far-infrared photometry of 31 reddened QSOs that show evidence for radiatively driven outflows originating from active galactic nuclei (AGNs) in their rest-frame UV spectra. We ...use these data to study the relationships between the AGN-driven outflows, and the AGN and starburst infrared luminosities. We find that FeLoBAL QSOs are invariably IR-luminous, with IR luminosities exceeding 10 super(12) L sub(middot in circle) in all cases. The AGN supplies 76% of the total IR emission, on average, but with a range from 20% to 100%. We find no evidence that the absolute luminosity of obscured star formation is affected by the AGN-driven outflows. Conversely, we find an anticorrelation between the strength of AGN-driven outflows, as measured from the range of outflow velocities over which absorption exceeds a minimal threshold, and the contribution from star formation to the total IR luminosity, with a much higher chance of seeing a starburst contribution in excess of 25% in systems with weak outflows than in systems with strong outflows. Moreover, we find no convincing evidence that this effect is driven by the IR luminosity of the AGN. We conclude that radiatively driven outflows from AGNs can have a dramatic, negative impact on luminous star formation in their host galaxies. We find that such outflows act to curtail star formation such that star formation contributes less than ~25% of the total IR luminosity. We also propose that the degree to which termination of star formation takes place is not deducible from the IR luminosity of the AGN.
We investigate the relation between star formation rates (
$\dot{{M}}_s$
) and AGN properties in optically selected type 1 quasars at 2 < z < 3 using data from Herschel and the SDSS. We find that
...$\dot{{M}}_s$
remains approximately constant with redshift, at 300 ± 100 M⊙ yr−1. Conversely,
$\dot{{M}}_s$
increases with AGN luminosity, up to a maximum of ∼ 600 M⊙ yr−1, and with C iv FWHM. In context with previous results, this is consistent with a relation between
$\dot{{M}}_s$
and black hole accretion rate (
$\dot{{M}}_{{\rm bh}}$
) existing in only parts of the
$z-\dot{{M}}_{s}-\dot{{M}}_{{\rm bh}}$
plane, dependent on the free gas fraction, the trigger for activity, and the processes that may quench star formation. The relations between
$\dot{{M}}_s$
and both AGN luminosity and C iv FWHM are consistent with star formation rates in quasars scaling with black hole mass, though we cannot rule out a separate relation with black hole accretion rate. Star formation rates are observed to decline with increasing C iv equivalent width. This decline can be partially explained via the Baldwin effect, but may have an additional contribution from one or more of three factors; M
i
is not a linear tracer of L
2500, the Baldwin effect changes form at high AGN luminosities, and high C iv EW values signpost a change in the relation between
$\dot{{M}}_s$
and
$\dot{{M}}_{{\rm bh}}$
. Finally, there is no strong relation between
$\dot{{M}}_s$
and Eddington ratio, or the asymmetry of the C iv line. The former suggests that star formation rates do not scale with how efficiently the black hole is accreting, while the latter is consistent with C iv asymmetries arising from orientation effects.
ABSTRACT We present the Herschel SPIRE Fourier Transform Spectroscopy (FTS) atlas for a complete flux-limited sample of local ultraluminous infrared galaxies (ULIRGs) as part of the HERschel Ultra ...Luminous InfraRed Galaxy Survey (HERUS). The data reduction is described in detail and was optimized for faint FTS sources ,with particular care being taken for the subtraction of the background, which dominates the continuum shape of the spectra. To improve the final spectra, special treatment in the data reduction has been given to any observation suffering from artifacts in the data caused by anomalous instrumental effects. Complete spectra are shown covering 200-671 m, with photometry in the SPIRE bands at 250, 350, and 500 m. The spectra include near complete CO ladders for over half of our sample, as well as fine structure lines from C i 370 m, C i 609 m, and N ii 205 m. We also detect H2O lines in several objects. We construct CO spectral line energy distributions (SLEDs) for the sample, and compare their slopes with the far-infrared (FIR) colors and luminosities. We show that the CO SLEDs of ULIRGs can be broadly grouped into three classes based on their excitation. We find that the mid-J (5 < J < 8) lines are better correlated with the total FIR luminosity, suggesting that the warm gas component is closely linked to recent star formation. The higher J transitions do not linearly correlate with the FIR luminosity, consistent with them originating in hotter, denser gas that is unconnected to the current star formation. We conclude that in most cases more than one temperature component is required to model the CO SLEDs.
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