Finding ultracool brown dwarfs  with 
MegaCam on CFHT: method and first results

Delorme, P.; Willott, Chris J.; Forveille, T.; Delfosse, X.; Reylé, C.; Bertin, E.; Li, Albert; Artigau, Étienne; Robin, A. C.; Allard, F.; Doyon, René; Hill, Gary J.

doi:10.1051/0004-6361:20078843

Cited by 76 publications

(94 citation statements)

References 35 publications

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“…It therefore provides (at least at a good signal-to-noise ratio) a good selection criteria to identify ultracool brown dwarfs. They usually have z − J > 3.8, as confirmed by atmosphere models such as BT-Settl (Allard et al 2007), synthetic MegaCam/WIRCam colours derived from known objects (Delorme et al 2008b) and direct observational data (Delorme et al 2008a;Burningham et al 2008Burningham et al , 2009. Models suggest that cooler objects, not yet discovered (T < 500 K), are even redder.…”

Section: Far-red and Near Infrared Photometric Properties Of Brown Dwmentioning

confidence: 88%

“…At those wavelengths the steep slope of their spectra stands out, and they have very distinctively red i − z and z − J colours. The CFBD Survey (Delorme et al 2008b) took advantage of their distinctive i − z colours to identify hundreds of L and T-dwarfs. However, the reddest and coolest brown dwarfs have extremely red z − J colours and are much easier to detect in the NIR than on original CFBDS far-red images.…”

Section: Far-red and Near Infrared Photometric Properties Of Brown Dwmentioning

confidence: 99%

“…The wealth of data from these surveys necessitate a complex dedicated computer analysis to single out relevant scientific information. These surveys, such as DENIS (Epchtein et al 1997), SDSS (York et al 2000), 2MASS (Skrutskie et al 2006), UKIDSS (Lawrence et al 2007), and CFBDS (Delorme et al 2008b) contain hundreds of millions of astrophysical sources and led to many advances in various fields, notably to identify extremely rare objects and build robust statistical studies.…”

Section: Introductionmentioning

confidence: 99%

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Extending the Canada-France brown dwarfs survey to the near-infrared: first ultracool brown dwarfs from CFBDSIR

Delorme

Forveille

et al. 2010

A&A

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Aims. We present the first results of the ongoing Canada-France Brown Dwarfs Survey-InfraRed, hereafter CFBDSIR, a near infrared extension to the optical wide-field survey CFBDS. Our final objectives are to constrain ultracool atmosphere physics by finding a statistically significant sample of objects cooler than 650 K and to explore the ultracool brown dwarf mass function building on a well-defined sample of such objects. Methods. We identify candidates in CFHT/WIRCam J and CFHT/MegaCam z images using optimised psf-fitting, and follow them up with pointed, near-infrared imaging with SOFI at the NTT. We finally obtain low-resolution spectroscopy of the coolest candidates to characterise their atmospheric physics. Results. We have so far analysed and followed up all candidates on the first 66 square degrees of the 335 square degree survey. We identified 55 T-dwarfs candidates with z − J > 3.5 and have confirmed six of them as T-dwarfs, including 3 that are strong laterthan-T8 candidates, based on their far-red and NIR colours. We also present here the NIR spectra of one of these ultracool dwarfs, CFBDSIR1458+1013, which confirms it as one of the coolest brown dwarf known, possibly in the 550-600 K temperature range. Conclusions. From the completed survey we expect to discover 10 to 15 dwarfs later than T8, more than doubling the known number of such objects. This will enable detailed studies of their extreme atmospheric properties and provide a stronger statistical basis for studies of their luminosity function.

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Section: Far-red and Near Infrared Photometric Properties Of Brown Dwmentioning

confidence: 88%

Section: Far-red and Near Infrared Photometric Properties Of Brown Dwmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Extending the Canada-France brown dwarfs survey to the near-infrared: first ultracool brown dwarfs from CFBDSIR

Delorme

Forveille

et al. 2010

A&A

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“…Leggett et al 2000), UKIDSS (e.g. Pinfield et al 2008), and CFBDS surveys (Delorme et al 2008). Their infrared spectra are dominated by the CH 4 and H 2 O absorption bands and by H 2 resonant absorption (e.g.…”

Section: Interlopersmentioning

confidence: 99%

Evidence of a fast evolution of the UV luminosity function beyond redshift 6 from a deep HAWK-I survey of the GOODS-S field

Castellano¹,

Fontana²,

Boutsia³

et al. 2010

A&A

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Aims. We perform a deep search for galaxies in the redshift range 6.5 ≤ z ≤ 7.5, to measure the evolution of the number density of luminous galaxies in this redshift range and derive useful constraints on the evolution of their luminosity function. Methods. We present here the first results of an ESO Large Programme, which exploits the unique combination of area and sensitivity provided in the near-IR by the camera Hawk-I at the VLT. We have obtained two Hawk-I pointings on the GOODS South field for a total of ∼32 observing hours, covering ∼90 arcmin 2 . The images reach Y = 26.7 mag for the two fields. We used public ACS images in the z band to select z-dropout galaxies with the colour criteria Z − Y ≥ 1, Y − J < 1.5, and Y − K < 2. The other public data in the UBVRIJK bands are used to reject possible low redshift interlopers. The output has been compared with extensive Monte Carlo simulations to quantify the observational effects of our selection criteria, as well as the effects of photometric errors. Results. We detect 7 high-quality candidates in the magnitude range Y = 25.5−26.7. This interval samples the critical range for M * at z > 6 (M 1500 −19.5 to −21.5). After accounting for the expected incompleteness, we rule out a luminosity function constant from z = 6 to z = 7 at a 99% confidence level, even including the effects of cosmic variance. For galaxies brighter than M 1500 = −19.0, we derive a luminosity density ρ UV = 1.5 +2.0 −0.9 × 10 25 erg s −1 Hz −1 Mpc −3 , implying a decrease by a factor 3.5 from z = 6 to z 6.8. On the basis of our findings, we make predictions for the surface densities expected in future surveys, based on ULTRA-VISTA, HST-WFC3, or JWST-NIRCam, evaluating the best observational strategy to maximise their impact.

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“…In other words, is the solar neighbourhood populated by as many cool brown dwarfs as red dwarf stars? Several new near-infrared surveys like UKIDSS 1 , CFBDS (Delorme et al 2008b) and WISE (Wright 2008;Mainzer et al 2009) try to answer this question by going deeper than the Two Micron All Sky Survey (2MASS; Skrutskie et al 2006) to detect a new class of ultracool brown dwarfs, so-called Y dwarfs.…”

Section: Introductionmentioning

confidence: 99%

ULAS J141623.94+134836.3 – a faint common proper motion companion of a nearby L dwarf

Scholz¹

2010

A&A

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Aims. New near-infrared large-area sky surveys (e.g. UKIDSS, CFBDS, WISE) go deeper than 2MASS and aim at detecting brown dwarfs lurking in the solar neighbourhood that are even fainter than the latest known T-type objects, so-called Y dwarfs. Methods. Using UKIDSS data, we found a faint brown dwarf candidate with very red optical-to-near-infrared, but extremely blue near-infrared colours next to the recently discovered nearby L dwarf SDSS J141624.08+134826.7. We checked if the two objects are co-moving by studying their parallactic and proper motion and compared the new object with known T dwarfs. Results. The astrometric measurements are consistent with a physical pair (sep ≈ 75 AU) at a distance d ≈ 8 pc. The extreme colour (J − K ≈ −1.7) and absolute magnitude (M J = 17.78 ± 0.46 and M K = 19.45 ± 0.52) make the new object appear as one of the coolest (T eff ≈ 600 K) and nearest brown dwarfs, probably of late-T spectral type and possibly with a high surface gravity (log g ≈ 5.0).

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Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results

Cited by 76 publications

References 35 publications

Extending the Canada-France brown dwarfs survey to the near-infrared: first ultracool brown dwarfs from CFBDSIR

Extending the Canada-France brown dwarfs survey to the near-infrared: first ultracool brown dwarfs from CFBDSIR

Evidence of a fast evolution of the UV luminosity function beyond redshift 6 from a deep HAWK-I survey of the GOODS-S field

ULAS J141623.94+134836.3 – a faint common proper motion companion of a nearby L dwarf

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