ALMA photometry of extragalactic radio sources

Bonato, M.; Liuzzo, E.; Herranz, D.; González‐Nuevo, J.; Bonavera, L.; Tucci, M.; Massardi, M.; Zotti, G. de; Negrello, M.

doi:10.1093/mnras/stz465

Cited by 22 publications

(17 citation statements)

References 18 publications

(25 reference statements)

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“…We built a new catalog of candidate blazars, dubbed ABC, derived from the ALMA Calibrator Catalogue by Bonato et al (2019). The ABC catalog fills, at least partly, the lack of |b| < 10 • blazars in Roma-BZCAT, providing low Galactic latitude candidate counterparts to unassociated high-energy sources.…”

Section: Discussionmentioning

confidence: 99%

“…Then we excluded the 1391 sources with a match in the Roma-BZCAT from the sample of 3364 ACC sources, narrowing our selection down to 1973 sources. For the sources in ACC Bonato et al (2019), the authors evaluated the low frequency spectral index, α low , between 1 and 5 GHz using the 1.4 GHz flux densities from NVSS, SUMSS, GB6, and PMN survey catalogs. We then considered only the sources classified in the ACC that are likely to be blazars, that is, sources with α low < −0.5 or demonstrating evidence of variability or γ-ray emission.…”

Section: Sample Selectionmentioning

confidence: 99%

“…They were primarily drawn from "seed" catalogs, such as those of the Very Long Array (VLA), the SubMillimeter Array (SMA), the Australia Telescope Compact Array (ATCA), and the Combined Radio All-Sky Targeted Eight-GHz Survey (CRATES) 1 . The ALMA Calibrator Catalogue (ACC; Bonato et al 2019) contains 3364 sources, whose distribution in Galactic coordinates is presented in the left panel of Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

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A new multiwavelength census of blazars

Paggi

Bonato

Raiteri

et al. 2020

A&A

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Context. Blazars are the rarest and most powerful active galactic nuclei. They play a crucial and expanding role in the multifrequency and multimessenger astrophysics of today. Dominating the high-energy extragalactic sky, they have been recently associated with high-energy astrophysical neutrinos and they may be among the accelerators of the ultra-high energy cosmic rays. Current blazar catalogs, however, are incomplete and they are depleted, in particular, at low Galactic latitudes. Aims. Our study is aimed at augmenting the current blazar census, starting from a sample of ALMA calibrators that provides more homogeneous sky coverage, especially at low Galactic latitudes, to build a catalog of blazar candidates that can provide candidate counterparts to unassociated γ-ray sources and sources of high-energy neutrino emission or ultra-high energy cosmic rays. Methods. Based on the ALMA Calibrator Catalog, we compiled a selection of 1580 ALMA Blazar Candidates (ABCs) for which we collected multiwavelength information, including Gaia photometric, parallax, and proper motion data, as well as SDSS and LAMOST photometric and spectral data, WISE photometric data, X-ray (Swift-XRT, Chandra-ACIS and XMM-Newton-EPIC) count-rates and spectra, and Fermi-LAT fluxes and spectral slopes. We also compared our ALMA Blazar Candidates with existing blazar catalogs, such as 4FGL, 3HSP, WIBRaLS2, and the KDEBLLACS. Results. The ABC catalog fills in the gaps with regard to low Galactic latitude sources in current blazar catalogs. By cross-matching this catalog with Gaia DR2, SDSS DR12, LAMOST DR5, AllWISE, and 4FGL catalogs, we obtained 805, 295, 31, 1311, and 259 matches, respectively. ALMA Blazar Candidates are significantly dimmer than known blazars in the Gaia g band, while the difference in the Gaia b − r color between the two populations is less pronounced. Also, ABC sources appear bluer in SDSS than known blazars, although with low statistical significance. Most ABCs classified as QSO and BL Lac fall into the SDSS color regions of low redshift quasars, with some QSOs entering the regions of higher redshift quasars. We collected 110 optical spectra in SDSS DR12 and LAMOST DR5, which mostly classify the corresponding sources as QSO (98), while 12 sources turned out to be galactic objects. Regarding the WISE colors, we found that ABC sources are significantly bluer than known blazars in the w2 − w3 and w3 − w4 colors. In X-ray, we detected 173 ABCs and we were able to extract X-ray spectra for 92 of them. Our sources are, on average, similar in the X-ray band to known blazars in terms of count rates and spectral slopes, implying that our sample covers the same region of the blazar parameter space in this band. A comparison of γ-ray properties shows that the ABCs are, on average, dimmer and that their γ-ray spectra are softer than known blazars, indicating a significant contribution on the part of FSRQ sources. Making use of WISE colors, we classified 715 ABCs as candidate γ-ray blazar of different classes. Conclusions. We built a new catalog of 1580 candidate blazars with a rich multiwavelength data-set, filling in the gaps for low Galactic latitude sources in current blazar catalogs. This will be particularly important for the identification of the source population of high-energy neutrinos or ultra-high energy cosmic rays, or to verify the Gaia optical reference frame. In addition, ALMA Blazar Candidates can be investigated both through optical spectroscopic observation campaigns or through repeated photometric observations for variability studies. In this context, the data collected by the upcoming LSST surveys will provide a key tool for investigating the possible blazar nature of these sources.

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Section: Discussionmentioning

confidence: 99%

Section: Sample Selectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A new multiwavelength census of blazars

Paggi

Bonato

Raiteri

et al. 2020

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“…Three of the four planned observing sessions were executed, accumulating a total on-source time of 143.8 min with 6.05 s integrations. Either 43 or 46 12-m antennas were operational, with baselines ranging between 15.1 m and 740.5 m. The BL Lac object J0854+2006 served as the amplitude, bandpass, and pointing calibrator, and the flat-spectrum radio quasar J0909+0121 as the phase calibrator (Bonato et al 2019).…”

Section: Alma Co (3−2) Spectral Line Imagingmentioning

confidence: 99%

A Long Stream of Metal-Poor Cool Gas around a Massive Starburst Galaxy at z = 2.67

Fu,

Xue,

Prochaska

et al. 2021

Preprint

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We present the first detailed dissection of the circumgalactic medium (CGM) of massive starburst galaxies at z > 2. Our target is a submillimeter galaxy (SMG) at z = 2.674 that has a star formation rate of 1200 M ⊙ yr −1 and a molecular gas reservoir of 1.3 × 10 11 M ⊙ . We characterize its CGM with two background QSOs at impact parameters of 93 kpc and 176 kpc. We detect strong H I and metal-line absorption near the redshift of the SMG towards both QSOs, each consisting of three main subsystems spanning over 1500 km s −1 . The absorbers show remarkable kinematic and metallicity coherence across a separation of ∼86 kpc. In particular, the cool gas in the CGM of the SMG exhibits high H I column densities (log N HI /cm −2 = 20.2, 18.6), low metallicities ([M/H] ≈ −2.0), and similar radial velocities (δv ∼ −300 km s −1 ). While the H I column densities match previous results on the CGM around QSOs at z > 2, the metallicities are lower by more than an order-ofmagnitude. The large physical extent, the velocity coherence, the high surface density, and the low metallicity are all consistent with the cool, inflowing, and near-pristine gas streams predicted to penetrate hot massive halos at z > 1.5. We estimate a total gas accretion rate of ∼100 M ⊙ yr −1 from three such streams, which falls short of the star formation rate but is consistent with simulations. At this rate, it takes about a billion years to acquire the molecular gas reservoir of the central starburst.

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“…The γ-ray data are accumulated for the period from MJD 57748 to MJD 57753. The data in the mm/sub-mm band are from the ALMA catalog from the observations of bright compact radio sources in different bands between May 2011 and July 2018 (Bonato et al 2019). From the many observations of CTA 102, only the data from the observations carried out on December 17, 18 and 29, 2016 and on January 8, 2017, which are nearly simultaneous with the studied flare, were considered.…”

Section: Origin Of Multiwavelength Emissionmentioning

confidence: 99%

Investigation of the γ-ray spectrum of CTA 102 during the exceptional flaring state in 2016–2017

Sahakyan

2020

A&A

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The flat spectrum radio quasar CTA 102 entered an extended period of activity from 2016 to 2017 during which several strong γ-ray flares were observed. Using Fermi large area telescope data a detailed investigation of γ-ray spectra of CTA 102 during the flaring period is performed. In several periods the γ-ray spectrum is not consistent with a simple power-law, having a hard photon index with an index of ∼ (1.8 − 2.0) that shows a spectral cutoff around an observed photon energy of ∼ (9 − 16) GeV. The internal γ-ray absorption via photon-photon pair production on the broad-line-region-reflected photons cannot account for the observed cutoff/break even if the emitting region is very close to the central source. This cut-off/break is likely due to a similar intrinsic break in the energy distribution of emitting particles. The origin of the spectral break is investigated through the multiwavelength modeling of the spectral energy distribution, considering a different location for the emitting region. The observed X-ray and γ-ray data is modeled as inverse Compton scattering of synchrotron and/or external photons on the electron population that produce the radio-to-optical emission which allowed to constrain the power-law index and cut-off energy in the electron energy distribution. The obtained results are discussed in the context of a diffusive acceleration of electrons in the CTA 102 jet.

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ALMA photometry of extragalactic radio sources

Cited by 22 publications

References 18 publications

A new multiwavelength census of blazars

A new multiwavelength census of blazars

A Long Stream of Metal-Poor Cool Gas around a Massive Starburst Galaxy at z = 2.67

Investigation of the γ-ray spectrum of CTA 102 during the exceptional flaring state in 2016–2017

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