The bright end of the infrared luminosity functions and the abundance of hyperluminous infrared galaxies

Abstract

Aims. We provide the most accurate estimate yet of the bright end of the infrared (IR) luminosity functions (LFs) and the abundance of hyperluminous IR galaxies (HLIRGs) with IR luminosities > 10 13 L , thanks to the combination of the high sensitivity, angular resolution, and large area of the LOFAR Deep Fields, which probes an unprecedented dynamic range of luminosity and volume. Methods. We cross-match Herschel sources and LOFAR sources in Boötes (8.63 deg 2), Lockman Hole (10.28 deg 2), and ELAIS-N1 (6.74 deg 2) with rms sensitivities of ∼ 32, 22, and 20 µJy beam −1 , respectively. We divide the matched samples into 'unique' and 'multiple' categories. For the multiple matches, we de-blend the Herschel fluxes using the LOFAR positions and the 150-MHz flux densities as priors. We perform spectral energy distribution (SED) fitting, combined with multi-wavelength counterpart identifications and photometric redshift estimates, to derive IR luminosities. Results. The depth of the LOFAR data allows us to identify highly complete (∼ 92% completeness) samples of bright Herschel sources with a simple selection based on the 250 µm flux density (45, 40, and 35 mJy in Boötes, Lockman Hole, and ELAIS-N1, respectively). Most of the bright Herschel sources fall into the unique category (i.e. a single LOFAR counterpart). For the multiple matches, there is excellent correspondence between the radio emission and the far-IR emission. We find a good agreement in the IR LFs with a previous study out to z ∼ 6 which used de-blended Herschel data. Our sample gives the strongest and cleanest indication to date that the population of HLIRGs has surface densities of ∼ 5 to ∼ 18 / deg 2 (with variations due to a combination of the applied flux limit and cosmic variance) and an uncertainty of a factor of 2. In comparison, the GALFORM semi-analytic model significantly under-predicts the abundance of HLIRGs.

UNCOVER: A NIRSpec Identification of a Broad-line AGN at z = 8.50

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JWST Insight into a Lensed HST-dark Galaxy and Its Quiescent Companion at z = 2.58

“…Recent studies show that a considerable fraction of these galaxies at high redshifts are missed by the deepest HST surveys due to their extreme faintness in optical and near-infrared (NIR). The presence of these z > 2-3 dusty star-forming population has been demonstrated by a large number of detections with Spitzer Space Telescope (Spitzer) and Herschel Space Observatory (Herschel; see Huang et al 2011;Caputi et al 2012;Alcalde Pampliega et al 2019), as well as submillimeter and radio regimes (Talia et al 2021;Wang et al 2021) specifically by Atacama Large Millimeter/submillimeter Array (ALMA; Simpson et al 2014;Franco et al 2018;Wang et al 2019;Williams et al 2019;Yamaguchi et al 2019;Umehata et al 2020;Caputi et al 2021;Manning et al 2022). It is yet unclear whether these apparently rare objects form a part of a larger and more elusive population.…”

Stellar and black hole assembly inz< 0.3 infrared-luminous mergers: intermittent starbursts versus super-Eddington accretion

“…Moreover, the merger itself may transform disk-like progenitors into elliptical remnants (Barnes & Hernquist 1996;Genzel et al 2001), with some fraction also passing through an optical quasar phase (Sanders et al 1988;Tacconi et al 2002;Farrah et al 2009). At higher redshifts the mechanisms behind high rates of star foramtion and SMBH accretion may be more diverse, but mergers remain important up to at least ∼ 6, and may trigger even higher star formation and black hole accretion rates than their local counterparts (Alexander et al 2005;Pitchford et al 2016;Marrone et al 2018;Rowan-Robinson et al 2018;Gullberg et al 2019;Wang et al 2021;Gao et al 2021). Reviews of their properties are in Sanders & Mirabel (1996); Blain et al (2002); Lonsdale et al (2006); Casey et al (2014) and Pérez-Torres et al (2021).…”