arXiv subjects

Nadia L. Zakamska

Publications and source records attributed to Nadia L. Zakamska.

At least 73 records · Page 4Linked to original sources

arXiv2022

Enhancement of Double-Close-Binary Quadruples

Double-close-binary quadruples (2+2 systems) are hierarchical systems of four stars where two short-period binary systems move around their common center of mass on a wider orbit. Using Gaia Early Data Release 3, we search for comoving pairs where both components are eclipsing binaries. We present eight 2+2 quadruple systems with inner orbital periods of $<$ 0.4 days and with outer separations of $\gtrsim 1000$ AU. All but one system are newly discovered by this work, and we catalog their orbital information measured from their light curves. We find that the occurrence rate of 2+2 quadruples is 7.3 $\pm$ 2.6 times higher than what is expected from random pairings of field stars. At most a factor of $\sim$2 enhancement may be explained by the age and metallicity dependence of the eclipsing binary fraction in the field stellar population. The remaining factor of $\sim$3 represents a genuine enhancement of the production of short-period binaries in wide-separation ($>10^3$ AU) pairs, suggesting a close binary formation channel that may be enhanced by the presence of wide companions.

astro-ph.SR↗

arXiv2021

Varstrometry for Off-nucleus and Dual sub-Kpc AGN (VODKA): Hubble Space Telescope Discovers Double Quasars

Dual supermassive black holes (SMBHs) at $\sim$kpc scales are the progenitor population of SMBH mergers and play an important role in understanding the pairing and dynamical evolution of massive black holes in galaxy mergers. Because of the stringent resolution requirement and the apparent rareness of these small-separation pairs, there are scarce observational constraints on this population, with few confirmed dual SMBHs at $<10$kpc separations at $z>1$. Here we present results from a pilot search for kpc-scale dual quasars selected with Gaia Data release 2 (DR2) astrometry and followed up with Hubble Space Telescope (HST) Wide Field Camera 3 dual-band (F475W and F814W) snapshot imaging. Our targets are quasars primarily selected with the varstrometry technique, i.e., light centroid jitter caused by asynchronous variability from both members in an unresolved quasar pair, supplemented by sub-arcsec pairs already resolved by Gaia DR2. We find an overall high fraction of HST-resolved pairs among the varstrometry-selected quasars (unresolved in Gaia DR2), $\sim 30-50\%$, increasing toward high redshift ($\sim 60-80\%$ at $z>1.5$). We discuss the nature of the 43 resolved sub-arcsec pairs based on HST and supplementary data. A substantial fraction ($\sim 40\%$) of these pairs are likely physical quasar pairs or gravitationally lensed quasars. We also discover a triple quasar candidate and a quadruply lensed quasar, which is among the smallest-separation quadruple lenses. These results provide important guidelines to improve varstrometry selection and follow-up confirmation of $\sim$kpc-scale dual SMBHs at high redshift.

astro-ph.HE↗

arXiv2021

A 99-minute Double-lined White Dwarf Binary from SDSS-V

We report the discovery of SDSS J133725.26+395237.7 (hereafter SDSS J1337+3952), a double-lined white dwarf (WD+WD) binary identified in early data from the fifth generation Sloan Digital Sky Survey (SDSS-V). The double-lined nature of the system enables us to fully determine its orbital and stellar parameters with follow-up Gemini spectroscopy and Swift UVOT ultraviolet fluxes. The system is nearby ($d = 113$ pc), and consists of a $0.51\, M_\odot$ primary and a $0.32\, M_\odot$ secondary. SDSS J1337+3952 is a powerful source of gravitational waves in the millihertz regime, and will be detectable by future space-based interferometers. Due to this gravitational wave emission, the binary orbit will shrink down to the point of interaction in $\approx 220$ Myr. The inferred stellar masses indicate that SDSS J1337+3952 will likely not explode as a Type Ia supernova (SN Ia). Instead, the system will probably merge and evolve into a rapidly rotating helium star, and could produce an under-luminous thermonuclear supernova along the way. The continuing search for similar systems in SDSS-V will grow the statistical sample of double-degenerate binaries across parameter space, constraining models of binary evolution and SNe Ia.

astro-ph.SR↗

arXiv2021

Powerful winds in high-redshift obscured and red quasars

Quasar-driven outflows must have made their most significant impact on galaxy formation during the epoch when massive galaxies were forming most rapidly. To study the impact of quasar feedback we conducted rest-frame optical integral field spectrograph (IFS) observations of three extremely red quasars (ERQs) and one type-2 quasar at $z=2-3$, obtained with the NIFS and OSIRIS instruments at the Gemini North and W. M. Keck Observatory with the assistance of laser-guided adaptive optics. We use the kinematics and morphologies of the [OIII] 5007Åand H$α$ 6563Åemission lines redshifted into the near-infrared to gauge the extents, kinetic energies and momentum fluxes of the ionized outflows in the quasars host galaxies. For the ERQs, the galactic-scale outflows are likely driven by radiation pressure in a high column density environment or due to an adiabatic shock. For the type-2 quasar, the outflow is driven by radiation pressure in a low column density environment or due to a radiative shock. The outflows in the ERQs carry a significant amount of energy ranging from 0.05-5$\%$ of the quasar's bolometric luminosity, powerful enough to have a significant impact on the quasar host galaxies. However, the outflows are likely only impacting the inner few kpc of each host galaxy. The observed outflow sizes are generally smaller than other ionized outflows observed at high redshift. The high ratio between the momentum flux of the ionized outflow and the photon momentum flux from the quasar accretion disk and high nuclear obscuration makes these ERQs great candidates for transitional objects where the outflows are likely responsible for clearing material in the inner regions of each galaxy, unveiling the quasar accretion disk at optical wavelengths.

astro-ph.GA↗

arXiv2021

The impact of low luminosity AGN on their host galaxies: A radio and optical investigation of the kpc-scale outflow in MaNGA 1-166919

One way an Active Galactic Nucleus (AGN) influences the evolution of their host galaxy is by generating a large-scale (kpc-scale) outflow. The content, energetics, and impact of such outflows depend on the properties of both the AGN and host galaxy, and understanding the relationship between them requires measuring the properties of all three. In this paper, we do so by analyzing recent radio and optical integral field unit (IFU) spectroscopic observations of MaNGA 1-166919. Our results indicate that the bi-conical outflow in this galaxy is powered by a low-luminosity, low-Eddington ratio AGN ejecting material that drives ~100-200 km/s shocks into the surrounding interstellar medium (ISM) -- producing the hot, ionized gas and relativistic particles associated with the observed outflow. The energetics of the relativistic and ionized gas material produced at this shock are comparable, and both the mass outflow and kinetic power of the ionized gas in this outflow are higher than other AGN with similar bolometric luminosities. Lastly, while the host galaxy's total star formation rate is comparable to that of other star-forming galaxies with a similar stellar mass, there is evidence that the outflow both suppresses and enhances star formation in its immediate surroundings.

astro-ph.GA↗

arXiv2021

Variability, periodicity and contact binaries in WISE

The time-series component of WISE is a valuable resource for the study of variable objects. We present an analysis of an all-sky sample of ~450,000 AllWISE+NEOWISE infrared light curves of likely variables identified in AllWISE. By computing periodograms of all these sources, we identify ~56,000 periodic variables. Of these, ~42,000 are short-period (P<1 day), near-contact or contact eclipsing binaries, many of which are on the main sequence. We use the periodic and aperiodic variables to test computationally inexpensive methods of periodic variable classification and identification, utilizing various measures of the probability distribution function of fluxes and of timescales of variability. The combination of variability measures from our periodogram and non-parametric analyses with infrared colors from WISE and absolute magnitudes, colors and variability amplitude from Gaia is useful for the identification and classification of periodic variables. Furthermore, we show that the effectiveness of non-parametric methods for the identification of periodic variables is comparable to that of the periodogram but at a much lower computational cost. Future surveys can utilize these methods to accelerate more traditional time-series analyses and to identify evolving sources missed by periodogram-based selections.

astro-ph.SR↗

arXiv2021

X-ray analysis of SDSS J165202.60+172852.4, an obscured quasar with outflows at peak galaxy formation epoch

We report on deep XMM-Newton and NuSTAR observations of the high redshift, z=2.94, extremely red quasar (ERQ), SDSS J165202.60+172852.4, with known galactic ionized outflows detected via spatially-resolved [OIII] emission lines. X-ray observations allow us to directly probe the accretion disk luminosity and the geometry and scale of the circumnuclear obscuration. We fit the spectra from the XMM-Newton/EPIC and NuSTAR detectors with a physically motivated torus model and constrain the source to exhibit a near Compton-thick column density of $N_H=(1.02^{+0.76}_{-0.41})\times10^{24}\textrm{ cm}^{-2}$, a near edge-on geometry with the line-of-sight inclination angle of $θ_i=85^{\circ}$, and a scattering fraction of $f_{sc}\sim 3$ %. The absorption-corrected, intrinsic 2-10 keV X-ray luminosity of $L_{\textrm{2-10}}=(1.4^{+1}_{-1}) \times10^{45} \textrm{ erg s}^{-1}$ reveals a powerful quasar that is not intrinsically X-ray weak, consistent with observed trends in other ERQs. We also estimate the physical properties of the obscuration, although highly uncertain: the warm ionized scattering density of $n_e \sim 7.5\times(10^2-10^3)\textrm{ cm}^{-3}$ and the obscuration mass of $M_{obsc} \sim 1.7\times(10^4-10^6) M_{\odot}$. As previously suggested with shallower X-ray observations, optical and infrared selection of ERQ has proved effective in finding obscured quasars with powerful outflow signatures. Our observations provide an in-depth view into the X-ray properties of ERQs and support the conclusions of severely photon-limited studies of obscured quasar populations at high redshifts.

astro-ph.GA↗

arXiv2020

The non-monotonic, strong metallicity dependence of the wide-binary fraction

The metallicity dependence of the wide-binary fraction in stellar populations plays a critical role in resolving the open question of wide binary formation. In this paper, we investigate the metallicity ([Fe/H]) and age dependence of the wide-binary fraction (binary separations between $10^3$ and $10^4$ AU) for field F and G dwarfs within 500 pc by combining their metallicity and radial velocity measurements from LAMOST DR5 with the astrometric information from Gaia DR2. We show that the wide-binary fraction strongly depends on the metallicity: as metallicity increases, the wide-binary fraction first increases, peaks at [Fe/H]$\simeq 0$, and then decreases at the high metallicity end. The wide-binary fraction at [Fe/H]$=0$ is about two times larger than that at [Fe/H]$=-1$ and [Fe/H]$=+0.5$. This metallicity dependence is dominated by the thin-disk stars. Using stellar kinematics as a proxy of stellar age, we show that younger stars have a higher wide-binary fraction at fixed metallicity close to solar. We propose that multiple formation channels are responsible for the metallicity and age dependence. In particular, the positive metallicity correlation at [Fe/H]$<0$ and the age dependence may be due to the denser formation environments and higher-mass clusters at earlier times. The negative metallicity correlation at [Fe/H]$>0$ can be inherited from the similar metallicity dependence of close binaries, and radial migration may play a role in enhancing the wide-binary fraction around the solar metallicity.

astro-ph.SR↗

arXiv2020

Computational Tools for the Spectroscopic Analysis of White Dwarfs

The spectroscopic features of white dwarfs are formed in the thin upper layer of their stellar photosphere. These features carry information about the white dwarf's surface temperature, surface gravity, and chemical composition (hereafter 'labels'). Existing methods to determine these labels rely on complex ab-initio theoretical models which are not always publicly available. Here we present two techniques to determine atmospheric labels from white dwarf spectra: a generative fitting pipeline that interpolates theoretical spectra with artificial neural networks, and a random forest regression model using parameters derived from absorption line features. We test and compare our methods using a large catalog of white dwarfs from the Sloan Digital Sky Survey (SDSS), achieving the same accuracy and negligible bias compared to previous studies. We package our techniques into an open-source Python module 'wdtools' that provides a computationally inexpensive way to determine stellar labels from white dwarf spectra observed from any facility. We will actively develop and update our tool as more theoretical models become publicly available. We discuss applications of our tool in its present form to identify interesting outlier white dwarf systems including those with magnetic fields, helium-rich atmospheres, and double-degenerate binaries.

astro-ph.SR↗

arXiv2020

A Gravitational Redshift Measurement of the White Dwarf Mass-Radius Relation

The mass-radius relation of white dwarfs is largely determined by the equation of state of degenerate electrons, which causes the stellar radius to decrease as mass increases. Here we observationally measure this relation using the gravitational redshift effect, a prediction of general relativity that depends on the ratio between stellar mass and radius. Using observations of over three thousand white dwarfs from the Sloan Digital Sky Survey and the Gaia space observatory, we derive apparent radial velocities from absorption lines, stellar radii from photometry and parallaxes, and surface gravities by fitting atmospheric models to spectra. By averaging the apparent radial velocities of white dwarfs with similar radii and, independently, surface gravities, we cancel out random Doppler shifts and measure the underlying gravitational redshift. Using these results, we empirically measure the white dwarf mass-radius relation across a wide range of stellar masses. Our results are consistent with leading theoretical models, and our methods could be used with future observations to empirically constrain white dwarf core composition and evolution.

astro-ph.SR↗

arXiv2020

Very wide companion fraction from Gaia DR2: a weak or no enhancement for hot jupiter hosts, and a strong enhancement for contact binaries

There is an ongoing debate on whether hot jupiter hosts are more likely to be found in wide binaries with separations of $\gtrsim 100$ AU. In this paper, we search for comoving, very wide companions with separations of $10^3-10^4$ AU for hot jupiter hosts and main-sequence contact binaries in Gaia DR2, and compare the very wide companion fractions with their object-by-object-matched field star samples. We find that $11.9\pm 2.5$% of hot jupiter hosts and $14.1\pm 1.0$% of contact binaries have companions at separations of $10^3-10^4$ AU. While the very wide companion fraction of hot jupiter hosts is a factor of $1.9\pm0.5$ larger than their matched field star sample, it is consistent, within $\sim1σ$, with that of matched field stars if the matching is only with field stars without close companions (within $\sim50$ AU) as is the case for hot jupiter hosts. The very wide companion fraction of contact binaries is a factor of $3.1\pm0.5$ larger than their matched field star sample, suggesting that the formation and evolution of contact binaries are either tied to or correlated with the presence of wide companions. In contrast, the weak enhancement of very wide companion fraction for hot jupiter hosts implies that the formation of hot jupiters is not as sensitive to those environment properties. Our results also hint that the occurrence rates of dual hot jupiter hosts and dual contact binaries may be higher than the expected values from random pairing of field stars, which may be due to their underlying metallicity and age dependence.

astro-ph.EP↗

arXiv2020

Ionized and hot molecular outflows in the inner 500 pc of NGC1275

The role of feedback from Active Galactic Nuclei (AGN) in the evolution of galaxies is still not not fully understood, mostly due to the lack of observational constraints in the multi-phase gas kinematics on the ten to hundred parsec scales. We have used the Gemini Near-infrared Integral Field Spectrograph (NIFS) to map the molecular and ionized gas kinematics in the inner 900$\times$900 pc$^2$ of the Seyfert galaxy NGC1275 at a spatial resolution of $\sim$70 pc. From the fitting of the CO absorption bandheads in the K-band, we derive a stellar velocity dispersion of $265\pm26$ km s$^{-1}$, which implies a black hole mass of $M_{\rm SMBH}=1.1^{+0.9}_{-0.5}\times10^9$ M$_\odot$. We find hot ($T\gtrsim1000$ K) molecular and ionized outflows with velocities of up to 2 000 km s$^{-1}$ and mass outflow rates of $2.7\times10^{-2} {\rm M_\odot}$ yr$^{-1}$ and $1.6 {\rm M_\odot}$ yr$^{-1}$, respectively, in each of these gas phases. The kinetic power of the ionized outflows corresponds to only 0.05 per cent of the luminosity of the AGN of NGC 1275, indicating that they are not powerful enough to provide significant AGN feedback, but may be effective in redistributing the gas in the central region of the galaxy. The AGN driven outflows seem to be responsible for the shocks necessary to produce the observed H$_2$ and [Fe II] line emission.

astro-ph.GA↗

arXiv2020

Formation of Orion Fingers

"Orion fingers" are a system of dozens of bowshocks, with the wings of shocks pointing to a common system of origin, which is centered on a dynamically disintegrating system of several massive stars. The shock heads propagate with velocities of up to 300-400 km/s, but the formation and physical properties of the "bullets" leading the shocks are not known. Here we summarize two possible scenarios for the formation of the "bullets" and the resulting bowshocks ("fingers"). In the first scenario, bullets are self-gravitating, Jupiter-mass objects which were formed rapidly and then ejected during the strong dynamical interactions of massive stars and their disks. This scenario naturally explains the similar timescales for the outflow of bullets and for the dynamical interaction of the massive stars, but has some difficulty explaining the observed high velocities of the bullets. In the second scenario, bullets are formed via hydrodynamic instabilities in a massive, infrared-driven wind, naturally explaining the high velocities and the morphology of outflow, but the bullets are not required to be self-gravitating. The processes that created the Orion fingers are likely not unique to this particular star-forming region and may result in free-floating, high-velocity, core-less planets.

astro-ph.GA↗

arXiv2020

Spatially-resolved UV diagnostics of AGN feedback: radiation pressure dominates in a prototypical quasar-driven superwind

Galactic-scale winds driven by active galactic nuclei (AGN) are often invoked to suppress star formation in galaxy evolution models, but the mechanisms driving these outflows are hotly debated. Two key AGN feedback models are (1) radiation pressure accelerating cool gas and (2) a hot outflowing wind entraining the ISM. Highly ionized emission-line diagnostics represent a powerful means of differentiating these scenarios because of their sensitivity to the expected compression of the ISM clouds by the hot wind. Here, we report the first spatially resolved UV emission spectroscopy of a prototypical (radio-quiet) quasar-driven superwind around the obscured quasar SDSSJ1356+1026 at z=0.123. We observe ratios of OVI/CIV, NV/CIV, and CIV/HeII that are remarkably similar for outflowing gas clouds <100 pc and ~10 kpc from the nucleus. Such similarity is expected for clouds with AGN radiation pressure dominated dynamics. Comparing the observed line emission to models of clouds in balance with radiation pressure and/or a hot wind, we rule out the presence of a dynamically important hot wind and constrain the ratio of hot gas pressure to radiation pressure to P_hot/P_rad<0.25 both at <100 pc and ~10 kpc from the nucleus. Moreover, the predictions of the radiation pressure confined cloud models that best fit observed UV line ratios are consistent with the observed diffuse X-ray spectrum. These results indicate that this AGN superwind is driven by radiation pressure or was driven by a hot wind that has since dissipated despite on-going AGN activity.

astro-ph.GA↗

arXiv2020

Ionised gas outflow signatures in SDSS-IV MaNGA active galactic nuclei

The prevalence of outflow and feedback signatures in active galactic nuclei (AGN) is a major unresolved question which large integral field unit (IFU) surveys now allow to address. In this paper, we present a kinematic analysis of the ionised gas in 2778 galaxies at z $\sim$ 0.05 observed by SDSS-IV MaNGA. Specifically, we measure the kinematics of the [OIII] λ5007Å emission line in each spatial element and fit multiple Gaussian components to account for possible non-gravitational motions of gas. Comparing the kinematics of the ionised gas between 308 MaNGA-selected AGN that have been previously identified through emission line diagnostics and sources not classified as AGN, we find that while 25% of MaNGA-selected AGN show [OIII] components with emission line widths of $>$ 500 km/s in more than 10% of their spaxels, only 7% of MaNGA non-AGN show a similar signature. Even the AGN that do not show nuclear AGN photoionisation signatures and that were only identified as AGN based on their larger scale photoionisation signatures show similar kinematic characteristics. In addition to obscuration, another possibility is that outflow and mechanical feedback signatures are longer lived than the AGN itself. Our measurements demonstrate that high velocity gas is more prevalent in AGN compared to non-AGN and that outflow and feedback signatures in low-luminosity, low-redshift AGN may so far have been underestimated. We show that higher luminosity MaNGA-selected AGN are able to drive larger scale outflows than lower luminosity AGN. But estimates of the kinetic coupling efficiencies are $<$ 1% and suggest that the feedback signatures probed in this paper are unlikely to have a significant impact on the AGN host galaxies. However, continuous energy injection may still heat a fraction of the cool gas and delay or suppress star formation in individual galaxies even when the AGN is weak.

astro-ph.GA↗

arXiv2019

Active galactic nuclei winds as the origin of the H$_2$ emission excess in nearby galaxies

In most galaxies, the fluxes of rotational H2 lines strongly correlate with star formation diagnostics (such as polycyclic aromatic hydrocarbons, PAH), suggesting that H2 emission from warm molecular gas is a minor byproduct of star formation. We analyse the optical properties of a sample of 309 nearby galaxies derived from a parent sample of 2,015 objects observed with the Spitzer Space Telescope. We find a correlation between the [OI]6300 emission-line flux and kinematics and the H2 S(3)9.665um/PAH11.3um. The [OI]6300 kinematics in Active Galactic Nuclei (AGN) can not be explained only by gas motions due to the gravitational potential of their host galaxies, suggesting that AGN driven outflows are important to the observed kinematics. While H2 excess also correlates with the fluxes and kinematics of ionized gas (probed by [OIII]), the correlation with [OI] is much stronger, suggesting that H2 and [OI] emission probe the same phase or tightly coupled phases of the wind. We conclude that the excess of H2 emission seen in AGN is produced by shocks due to AGN driven outflows and in the same clouds that produce the [OI] emission. Our results provide an indirect detection of neutral and molecular winds and suggest a new way to select galaxies that likely host molecular outflows. Further ground- and space-based spatially resolved observations of different phases of the molecular gas (cold, warm and hot) are necessary to test our new selection method.

astro-ph.GA↗

arXiv2019

Hubble Space Telescope Observations of Mira Variables in the Type Ia Supernova Host NGC 1559: An Alternative Candle to Measure the Hubble Constant

We present year-long, near-infrared Hubble Space Telescope WFC3 observations used to search for Mira variables in NGC 1559, the host galaxy of the Type Ia supernova (SN Ia) 2005df. This is the first dedicated search for Miras, highly-evolved low-mass stars, in a SN Ia host and subsequently the first calibration of the SN Ia luminosity using Miras in a role historically played by Cepheids. We identify a sample of 115 O-rich Miras with P < 400 days based on their light curve properties. We find that the scatter in the Mira Period-Luminosity Relation (PLR) is comparable to Cepheid PLRs seen in SN Ia supernova host galaxies. Using a sample of O-rich Miras discovered in NGC 4258 with HST F160W and its maser distance, we measure a distance modulus for NGC 1559 of mu1559 = 31.41 +/- 0.050 (statistical) +/- 0.060 (systematic) mag. Based on the light curve of the normal, well-observed, low-reddening SN 2005df, we obtain a measurement of the fiducial SN Ia absolute magnitude of MB0 = -19.27 +/- 0.13 mag. With the Hubble diagram of SNe Ia we find H0 = 72.7 +/- 4.6 kms-1 Mpc-1. Combining the calibration from the NGC 4258 megamaser and the Large Magellanic Cloud detached eclipsing binaries gives a best value of H0 = 73.3 +/- 4.0 km s-1 Mpc-1. This result is within 1-sigma of the Hubble constant derived using Cepheids and multiple calibrating SNe Ia. This is the first of four expected calibrations of the SN Ia luminosity from Miras which should reduce the error in H0 via Miras to ~3%. In light of the present Hubble tension and JWST, Miras have utility in the extragalactic distance scale to check Cepheid distances or calibrate nearby SNe in early-type host galaxies that would be unlikely targets for Cepheid searches.

astro-ph.CO↗

arXiv2019

Quantifying the Thermal Sunyaev-Zel'dovich Effect and Excess Millimeter Emission in Quasar Environments

In this paper we probe the hot, post-shock gas component of quasar-driven winds through the thermal Sunyaev-Zel'dovich (tSZ) effect. Combining datasets from the Atacama Cosmology Telescope, the $\textit{Herschel}$ Space Observatory, and the Very Large Array, we measure average spectral energy distributions (SEDs) of 109,829 optically-selected, radio quiet quasars from 1.4~GHz to 3000~GHz in six redshift bins between $0.3 1.91$, we measure the tSZ effect at $3.8σ$ significance with an amplitude corresponding to a total thermal energy of $3.1\times10^{60}$ ergs. If this energy is due to virialized gas, then our measurement implies quasar host halo masses are $\sim6\times10^{12}~h^{-1}$M$_\odot$. Alternatively, if the host dark matter halo masses are $\sim2\times10^{12}~h^{-1}$M$_\odot$ as some measurements suggest, then we measure a $>$90 per cent excess in the thermal energy over that expected due to virialization. If the measured SZ effect is primarily due to hot bubbles from quasar-driven winds, we find that $(5^{+1.2}_{-1.3}$) per cent of the quasar bolometric luminosity couples to the intergalactic medium over a fiducial quasar lifetime of 100 Myr. An additional source of tSZ may be correlated structure, and further work is required to separate the contributions. At $z\leq1.91$, we detect emission at 95 and 148~GHz that is in excess of thermal dust and optically thin synchrotron emission. We investigate potential sources of this excess emission, finding that CO line emission and an additional optically thick synchrotron component are the most viable candidates.

astro-ph.GA↗