Detection of galaxies with<i>Gaia</i>

Souza, R. E. de; Krone-Martins, A.; Anjos, S. dos; Ducourant, C.; Teixeira, R.

doi:10.1051/0004-6361/201423514

Cited by 18 publications

(26 citation statements)

References 23 publications

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“…This calculation shows that around 1.5×10 6 red and around 8×10 4 blue galaxies will be detected by Gaia. Therefore, a total number of ∼ 1.5 × 10 6 galaxies is expected, which is a factor 3 higher than the numbers predicted by de Souza et al (2014).…”

Section: On Board Galaxy Detectionmentioning

confidence: 63%

“…The SM window sent to Earth around the position of the detection is larger though, covering 4.72 × 2.12 arcsec. A detailed description of the detection process and the recognition strategy used in the on-board Video Processing Algorithm (VPA) may be found in de de Souza et al (2014) andde Bruijne et al (2015).…”

Section: Description Of the Gaia Datamentioning

confidence: 99%

“…Moreover, to accurately estimate the distance of a transient to the nucleus of its host galaxy, the astrometry for both components needs to be delivered by Gaia, and therefore the galaxy itself has to have the appropriate characteristics to be detected by the on-board detection algorithm. According to the galaxy detectability study in de Souza et al (2014), Gaia has a detection process optimised for point-like sources, leading to a selective galaxy detection, dominated by compact galaxy bulges or small elliptical galaxies. Therefore, our analysis focused on the bulge component only.…”

Section: Galaxy Detection Simulationmentioning

confidence: 99%

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Gaiatransient detection efficiency: hunting for nuclear transients

Blagorodnova

Velzen

Harrison

et al. 2015

Mon. Not. R. Astron. Soc.

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We present a study of the detectability of transient events associated with galaxies for the Gaia European Space Agency astrometric mission. We simulated the on-board detections, and on-ground processing for a mock galaxy catalogue to establish the properties required for the discovery of transient events by Gaia, specifically tidal disruption events (TDEs) and supernovae (SNe). Transients may either be discovered by the on-board detection of a new source or by the brightening of a previously known source. We show that Gaia transients can be identified as new detections on-board for offsets from the host galaxy nucleus of 0.1-0.5 arcsec, depending on magnitude and scanning angle. The Gaia detection system shows no significant loss of SNe at close radial distances to the nucleus. We used the detection efficiencies to predict the number of transients events discovered by Gaia. For a limiting magnitude of 19, we expect around 1300 SNe per year: 65% SN Ia, 28% SN II and 7% SN Ibc, and ∼20 TDEs per year.

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Section: On Board Galaxy Detectionmentioning

confidence: 63%

Section: Description Of the Gaia Datamentioning

confidence: 99%

Section: Galaxy Detection Simulationmentioning

confidence: 99%

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Gaiatransient detection efficiency: hunting for nuclear transients

Blagorodnova

Velzen

Harrison

et al. 2015

Mon. Not. R. Astron. Soc.

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“…The SP and LSS proper motions both fall as 1/r, but more distant objects can help break degeneracies with the SAD proper motion and suffer less from bias due to correlations of LSS peculiar velocities with our local motion. Gaia is only expected to observe galaxies with centrally concentrated brightness profiles, and is unlikely to be sensitive to galaxies with a large disk component (de Souza et al 2014). In particular, late-type spiral galaxies are unlikely to be present in Gaia data (de Bruijne et al 2015).…”

Section: Amplitude Estimators and The Hubble Constantmentioning

confidence: 99%

“…With the dramatic increase in data volume and quality it is timely to ask what precision astrometry can say about cosmology. Although not designed for this purpose, Gaia will measure the proper motions of some 10 6 galaxies (de Souza et al 2014;de Bruijne et al 2015), preferentially selecting objects which look most 'point-source-be used to infer the Hubble constant, H 0 , if the SP velocity is fixed by the CMB dipole. Bachchan et al (2016) forecast that Gaia can potentially make a ∼ 30% measurement of H 0 with this method, with further improvements possible if more galaxies can be detected.…”

Section: Introductionmentioning

confidence: 99%

Cosmology with extragalactic proper motions: harmonic formalism, estimators, and forecasts

Hall

2019

Monthly Notices of the Royal Astronomical Society

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We conduct a thorough study into the feasibility of measuring large-scale correlated proper motions of galaxies with astrometric surveys. We introduce a harmonic formalism for analysing proper motions and their correlation functions on the sphere based on spin-weighted spherical harmonics, and study the statistics of the transverse velocity field induced by large-scale structure. We use a likelihood formalism to derive optimal estimators for the secular parallax due to the Solar System's motion relative to distant objects, and compute the variance and bias due to peculiar velocities and relativistic aberration. We use a simulated catalogue of galaxy proper motions with radial distributions and noise properties similar to those expected from Gaia to forecast the detectability of the proper motion dipole, whose amplitude may be considered a proxy for the Hubble constant. We find cosmic variance to be the limiting source of noise for this measurement, forecasting a detectability of 1-2σ on a single component of the local velocity, increasing to 2-4σ (equivalent to a 25%-50% measurement of the Hubble constant) if the CMB dipole is included as prior information. We conduct a thorough study into the radial dependence of the signal-to-noise, finding that most of the information comes from galaxies closer than a few hundred Mpc. We forecast that the amplitude of peculiar transverse velocities can potentially be measured with 10σ significance; such a measurement would offer a unique probe of cosmic flows and a valuable test of the cosmological model. 1 http://sci.esa.int/gaia/ 2 http://ngvla.nrao.edu/ like', i.e. ellipticals with large bulge-to-disk components. Additionally, a large population of quasars will be observed to pin down the celestial reference frame (see, e.g. Gaia Collaboration et al. 2018).There are several potential uses of such a dataset for cosmology (see Darling et al. 2018 for a review). Firstly, since the Solar System moves relative to distant objects, there is a 'secular parallax' (SP) proper motion in the opposite direction to our local velocity. This proper motion has an amplitude of roughly 80 r/1 Mpc µas yr −1 , where r is the comoving distance to the object, and has a dipolar dependence on angle, anti-aligned with the velocity vector of the Solar System with respect to the CMB rest frame 3 . With spectroscopic redshifts as a proxy for distance, the SP proper motion may 3 We will often express quantities in the CMB rest frame, the frame in which the CMB dipole vanishes (Planck Collaboration et al. 2014). We assume that the matter rest frame (the frame in which the dipole anisotropy of peculiar velocities vanishes) and the CMB rest frame coincide, i.e. we do not consider the 'tilted universe' scenario of Turner

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Multiply imaged quasars in the Gaia DR1

Ducourant¹,

Delchambre²,

Finet³

et al. 2017

Proc. IAU

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Because of to its exceptional resolving power, Gaia should detect a few thousands gravitational lensed systems. These consist in multiple images of background quasars. The estimated number of lens phenomena in the sky, however, depends on the cosmological model considered. By taking into account the observational bias that will restrict the detection of lensed quasars, identification of these up to a given limiting magnitude will constrain the cosmological parameters.We have investigated the known gravitationally lensed quasars present in the Gaia DR1, and found that a significant number of components of these systems have been measured and are present in the Gaia DR1 catalogue although quasi none of them have all their components detected. We additionally examined the immediate surroundings of QSOs from the large Quasar catalogue, LQAC3, and detected several configurations compatible with gravitational lensing phenomena. A more global strategy to systematically detect the potential candidates in the various releases of the Gaia catalogue is presented.

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Detection of galaxies withGaia

Cited by 18 publications

References 23 publications

Gaiatransient detection efficiency: hunting for nuclear transients

Gaiatransient detection efficiency: hunting for nuclear transients

Cosmology with extragalactic proper motions: harmonic formalism, estimators, and forecasts

Multiply imaged quasars in the Gaia DR1

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