<i>Spitzer</i>IRAC Photometry of M, L, and T Dwarfs

Patten, B. M.; Stauffer, J. R.; Burrows, Adam; Marengo, Massimo; Hora, J. L.; Luhman, K. L.; Sonnett, S.; Henry, Todd J.; Raghavan, Deepak; Megeath, S. Thomas; Liebert, James; Fazio, G. G.

doi:10.1086/507264

Cited by 220 publications

(333 citation statements)

References 90 publications

(67 reference statements)

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“…None of our IRAC detected objects shows a (3.6−4.5) index over ∼0.4, in agreement with the colours expected for high-redshift LBGs. On the other hand, previous studies have found that cool dwarf stars show a broad range in the 4.5 μ luminosity, yielding values in the 3.6−4.5 colour index that can be much larger than those of our objects (up to 2.0 mag, see Patten et al 2006;Helling et al 2008), although lower colour indexes have also been observed for these objects.…”

Section: Detected Z > 65 Galaxiescontrasting

confidence: 85%

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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Section: Detected Z > 65 Galaxiescontrasting

confidence: 85%

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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“…The solid line represents the spectrophotometric sequence of field mid-M-to late-T-type dwarfs, shifted to match the brightness of the late-M-type cluster members (Zapatero Osorio et al 2008). For the field dwarfs, we use average absolute I-band magnitudes, I − J, and J − K s colours compiled by Caballero et al (2008a) 6 , J − H colours from Vrba et al (2004) 7 , and mid-infrared magnitudes from Patten et al (2006). In Fig.…”

Section: Resultsmentioning

confidence: 99%

Candidate free-floating super-Jupiters in the young σ Orionis open cluster

Bihain

Rebolo

Osorio³

et al. 2009

A&A

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Context. Free-floating substellar candidates with estimated theoretical masses of as low as ∼5 Jupiter masses have been found in the ∼3 Myr old σ Orionis open cluster. As the overlap with the planetary mass domain increases, the question of how these objects form becomes important. The determination of their number density and whether a mass cut-off limit exists is crucial to understanding their formation. Aims. We propose to search for objects of yet lower masses in the cluster and determine the shape of the mass function at low mass. Methods. Using new-and (re-analysed) published IZJHK s [3.6]−[8.0]-band data of an area of 840 arcmin 2 , we performed a search for LT-type cluster member candidates in the magnitude range J = 19.5-21.5 mag, based on their expected magnitudes and colours. Results. Besides recovering the T type object S Ori 70 and two other known objects, we find three new cluster member candidates, S Ori 72-74, with J ≈ 21 mag and within 12 arcmin of the cluster centre. They have theoretical masses of 4 +3 −2 M Jup and are among the least massive free-floating objects detected by direct imaging outside the Solar System. The photometry in archival Spitzer [3.6]-[5.8]-band images infers that S Ori 72 is an L/T transition candidate and S Ori 73 a T-type candidate, following the expected cluster sequence in the mid-infrared. Finally, the L-type candidate S Ori 74 with lower quality photometry is located at 11.8 arcsec (∼4250 AU) of a stellar member of σ Orionis and could be a companion. After contaminant correction in the area complete to J = 21.1 mag, we estimate that there remain between zero and two cluster members in the mass interval 6-4 M Jup . Conclusions. We present S Ori 73, a new candidate T type and candidate σ Orionis member of a few Jupiter masses. Our result suggests a possible turnover in the substellar mass spectrum below ∼6 Jupiter masses, which could be investigated further by wider and deeper photometric surveys.

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“…5. We compared synthetic spectra to the SED (optical, when available + 2MASS JHK + Spitzer fluxes) of M7-L7 field dwarfs studied in Patten et al (2006). Best fitting solutions were checked visually and were discarded, if needed.…”

Section: Behavior Of Atmospheric Models At the M-l Transitionmentioning

confidence: 99%

A library of near-infrared integral field spectra of young M–L dwarfs

Bonnefoy

Chauvin

Lagrange

et al. 2014

A&A

142

204

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Context. At young ages, low surface gravity affects the atmospheric properties of ultracool dwarfs. The impact on medium-resolution near-infrared (NIR) spectra has only been slightly investigated at the M-L transition so far. Aims. We present a library of NIR (1.1-2.45 µm) medium-resolution (R ∼ 1500-2000) integral field spectra of 15 young M6−L0 dwarfs. We aim at deriving updated NIR spectral type, luminosity, and physical parameters (T eff , log g, M, L/L ) for each source. This work also aims at testing the latest generation of BT-SETTL atmospheric models. Methods. We estimated spectral types using spectral indices and the spectra of young objects classified in the optical. We used the 2010 and 2012 releases of the BT-SETTL synthetic spectral grid and cross-checked the results with the DRIFT-PHOENIX models to derive the atmospheric properties of the sources. Results. We do not find significant differences between the spectra of young companions and those of young isolated brown dwarfs in the same spectral type range. We derive infrared spectral types L0 ± 1, L0 ± 1, M9.5 ± 0.5, M9.5 ± 0.5, M9.25 ± 0.25, M8 +0.5 −0.75 , and M8.5 ± 0.5 for AB Pic b, Cha J110913-773444, USco CTIO 108B, GSC 08047-00232 B, DH Tau B, CT Cha b, and HR7329B, respectively. The BT-SETTL and DRIFT-PHOENIX models yield close T eff and log g estimates for each source. The models seem to show a 600 +600 −300 K drop in the effective temperature at the M-L transition. Assuming the former temperatures are correct, we then derive new mass estimates that confirm that DH Tau B, USco CTIO 108B, AB Pic b, KPNO Tau 4, OTS 44, and Cha1109 lie inside or at the boundary of the planetary mass range. We combine the empirical luminosities of the M9.5-L0 sources to the T eff to derive semi-empirical radii estimates that do not match "hot-start" evolutionary models predictions at 1-3 Myr. We use complementary data to demonstrate that atmospheric models are able to reproduce the combined optical and infrared spectral energy distribution, together with the NIR spectra of these sources simultaneously. But the models still fail to represent the dominant features in the optical. This issue raises doubts on the ability of these models to predict effective temperatures from NIR spectra alone. Conclusions. The library provides templates for characterizing other young and late type objects. The study advocates the use of photometric and spectroscopic information over a broad range of wavelengths to study the properties of very low-mass young companions to be detected with the planet imagers (Subaru/SCExAO, LBT/LMIRCam, Gemini/GPI, VLT/SPHERE).

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SpitzerIRAC Photometry of M, L, and T Dwarfs

Cited by 220 publications

References 90 publications

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

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

Candidate free-floating super-Jupiters in the young σ Orionis open cluster

A library of near-infrared integral field spectra of young M–L dwarfs

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