Ben Burningham Brown dwarfs in large scale surveys - PowerPoint Presentation

Slide1

Ben Burningham

Brown dwarfs in large scale surveys

Brown dwarfs come of ageFuerteventura, 21st May 2013Slide2

Plan

a bit of historythe recent past the state of the artfuture challengesSlide3

The first wide area surveys

not digitalrelatively simple data pipelinec 1200 BC 36 stars

L5 dwarf @ ~100 au

T5 dwarf @ ~ 100 auSlide4

Greek pioneers

Timocharis & Aristillus c300BCHipparchus c135BC1022 starsm < 6updated in 964 (Sufi) and 1543 (Copernicus

)no brown dwarfs (but did discover precession of equinox)

L5 dwarf @ ~2000 au

T5 dwarf @ ~ 1000 auSlide5

The next 2000 years….

Tycho Brahe (1598):m < 61004 starsastrometric accuracy ~2’Lalande

et al (1801)50K starsm < 9Henry Draper (1918 – 1924)first spectroscopic surveyall sky

m

< 10

Bonner

Durchmusterung

  (1852

–

1859

); Cordoba

Durchmusterung

 (1892); Cape Photographic

Durchmusterung

(1896)

total 1 million stars 

all sky

m < 9 - 10

L5 dwarf @ ~10000 au

T 5dwarf @ ~2000 au Slide6

Photographic surveys

20th century dominated by three facilities:Palomar observatory:

POSS I (1949 – 1958) -27 to +90 degrees B ~ 21 POSS IIBj < 22.5, Rc < 20.8,

Ic

< 19.5

UK

&

ESO Schmidt telescopes:

ESO/SERC

Bj

~ 22.5,

Rc

~ 21

Ic

band

Ic

< 19

L5 dwarf @ ~20 pc

T5 dwarf @ ~ 4 pcSlide7

The first brown dwarfs - 1995

Rebolo

, Zapatero Osorio,& Martin, 1995

Nakajima et al 1995Slide8

Kelu - 1

L2 dwarf selected by proper motion1st epoch: ESO survey plates2nd epoch:

dedicated follow-up of 400 sq degsexamined with a blink comparatorRuiz et al (1997)Slide9

Legacy of photographic surveys

DSS I & IICatalogues from densitometer scans:GSC I & IIUSNOA, BsuperCOSMOSProper motion catalogues e.g. LHS, LSPM, PPMXL etc

identification of (ultra) cool >M7 dwarfsthe first L dwarf (Ruiz et al 1997)(the trickle before the flood)Slide10

The age of digital sky surveys

Facilitated by :new detectorsimprovements in data processing and storagefirst brown dwarfs identified in late 1990s (important: allows photometric selection)

New generation dominated by 3 surveys:DENIS2MASSSDSSSlide11

DENIS

Overviewsouthern sky (ESO 1m schmidt)i < 18.5, J < 16.5 , Ks < 14.0finished in 2001355 million sources

Results:49 L dwarfs: Delfosse et al (1997, 1999)Martin et al (1999)Bouy et al (2003)Kendall et al (2004)

Phan

-

Bao

et al (2008)

Martin et al (2010)

1 T dwarf

Artigua

et al (2010)

L5 dwarf @ ~40 pc

T5 dwarf @ ~ 20 pcSlide12

2MASS

All skyJHK (J < 16.5; H < 15.7; Ks < 15.2)>99% complete for J < 15.8, H < 15.1, Ks < 14.3game changer for substellar science

L5 dwarf @ ~45 pc T5 dwarf @ ~ 20 pcSlide13

Brown dwarfs in 2MASS

2MASS team searched via cross match of 2MASS against USNO for B+R band dropoutsvisual inspection to ensure no optical detectiondistinguished as L and T candidates based on JHK colourssubsequent searches cross matched 2MASS with e.g. SDSS, and included proper motion searches403 L dwarfs identified to-date:

Kirkpatrick et al (1999, 2000, 2008, 2010); Reid et al (2000, 2008); Gizis (2002); Gizis et al

(2000, 2003

);

Kendall

et al (

2003, 2007);

Cruz et al (2003, 2007);

Burgasser

et al (2003, 2004); Wilson et al (2003);

Folkes

et al (2007);

Metchev

et al (2008);

Looper

et al (2008) Sheppard & Cushing (2009); Scholz et al (2009); Geissler et al (2011)

55 T dwarfs:

Kirkpatrick et al (2000, 2010);

Burgasser

et al (1999, 2000, 2002, 2003, 2004, ); Cruz et al (2004)

Tinney

et al (2005);

Looper

et al (2007); Reid et al (2008) Slide14

SDSS

SDSS DR9: 14,555 square degrees932,891,133 “sources”1.7 million extragalactic spectra700K stellar spectraz’ < 20.8ish

“arguably the most successful scientific project ever undertaken”

L5 dwarf @ ~75 pc

T5 dwarf @ ~ 40 pcSlide15

Brown dwarfs in SDSS

381 L dwarfs to-date:photometric selection:Fan et al (2000) Hawley et al (2002); Geballe

et al (2002); Schneider et al (2002); Knapp et al (2004); Chiu et al (2006); Zhang et al (2009); Scholz et al (2009)

spectroscopic selection: Schmidt et al (2010)

highlights risky nature of photometric selection

57 T dwarfs:

Leggett et al (2000);

Geballe

et al (2002); Knapp et al (2004); Chiu et al (2006)Slide16

Highlights from the end of the beginning

definition of the “L” spectral class830 L dwarfs discoveredextended to halo population and young moving groupsdefinition of the “T” spectral class113 T dwarfs discoveredextended sequence to

Teff ~ 700K (T8)diversity of properties beyond Teff sequence apparentgravity?metallicity?dust properties?

Kirkpatrick et al 1999, 2000

Burgasser

et al 2006Slide17

Beyond stamp collecting

luminosity function of L dwarfs Cruz et al (2007)space density of T dwarfs  constraining the IMFAllen et al (2005)Metchev et al (2008)

binary statistics (e.g. Burgasser et al 2003)benchmarks (e.g. G570D, HD3651B)weather!!! (e.g. Radigan et al 2012; Buenzli

et al 2012)Slide18

Photometric survey exploitation cookbook

Select candidates from survey(s

) using colours

Follow-up photometry to remove contaminants

Spectroscopic confirmation

SCIENCE

e.g.

z

’ – J > 2.5

e.g. scattered M dwarfs;

SSOsSlide19

UKIRT Infrared Deep Sky Survey (UKIDSS)

Lawrence et al 2007

UKIDSS consists of 5 surveys

Large Area Survey (LAS)

3600

sq.

degs

, J = 19.6

2 epoch for ~1500 sq

degs

Galactic Plane Survey (GPS)

1800 sq.

degs

, K=19

Galactic Clusters Survey (GCS)

1400 sq.

degs

K=18.7

Deep Extragalactic Survey (DXS)

35 sq.

degs

, K=21.0

Ultra Deep Survey (UDS)

0.77 sq.

degs

, K=23.0

Casali et al 2007

L5 dwarf @ ~175 pc

T5 dwarf @ ~ 110 pcSlide20

171 T dwarfs identified

(Lodieu et al 2007; Pinfield et al 2008; Burningham et al (2008, 2009, 2010a,b, 2013)~70 (+) L dwarfs(Day-Jones et al 2013)

extended T sequence to Teff ~ 500K (Lucas et al 2011)halo T dwarfs (Smith et al – today!)more young L dwarfs (see

Marocco

et al poster)Slide21

CFBDS(IR)

~1000 sq degs in i & z (+NIR sections)early T8+ discovery (CFBDS 0059; Delorme et al 2008)L5 – T8 luminosit function (

Reyle et al 2010)extremely cool binary CFBDSIR J1458+1013AB (Liu et al 2011)planetary mass T dwarf CFBDSIR2149-0403 (Delorme et al 2012) Slide22

WISE – another leap forwards

all sky3.4, 4.6, 12, and 22 μmY dwarfs (Cushing et al 2011; Kirkpatrick et al 2012)

seriously, Teff ~ 300K brown dwarfs!!halo(?) T dwarfs (Gomes et al – today!)buckets of bright T dwarfs(Mace et al 2013)complementary data facilitating all sorts of cool science with UKIDSS, 2MASS etc

Kirkpatrick et al (2011)

L5 dwarf @ ~80 pc

T5 dwarf @ ~ 50 pc

Y dwarf @ ~12 pcSlide23

WISE vs UKIDSS – FIGHT!

J <18.3

18.3 < J <18.8Slide24

Survey league table

Survey L dwarfsT dwarfs

Y dwarfsDENIS49 1

0

2MASS

403

55

0

SDSS

381

57

0

UKIDSS

50

230

0

CFBDS(IR)

170(?)

45

1

WISE

10

176

14

VISTA-VHS

0

5

0 Slide25

The immediate future

VISTA:VISTA Hemisphere Survey (VHS)(Y)J(H)KsJ < 19.6 ~100K L0 – T5 ~2000 late-T dwarfs

VIKING1500 sq degsZYJHK J < 21.0Dark Energy Survey:

4000 sq

degs

grizy

(

z

< 24.7,

y

< 23.0)

PanStarrs

(+UKIRT Hemisphere Survey):

griz

(+J)

z

< 23.0 (+ J < 19.6)

L5 dwarf @ ~330 pc

T5 dwarf @ ~200 pc

~1 MILLION BROWN DWARFS!!!!

…and that’s before LSSTSlide26

What’s the point?

rare objects:benchmarkshalo T dwarfs/subdwarfsyoung objectsimproved space densityscale height for BDs (as a function of spectral type)

need kinematic data

need to use survey data for more than candidate selection Slide27

Photometric redshifts spectral types

Skrzypek

& Warren (poster here!) Slide28

Large scale spectroscopic surveys

EUCLID:VIS (<24.5 AB) + YJH (<24 AB) wide imaging survey over 15000 sq degYJH < 26.5 (AB) over 40 sq degs, slitless spectroscopy (J ~ 19?)

VLT-MOONS (proposed):500 sq arcminute, 500 object NIR MOSdeep survey key element of science casescale height for LT dwarfsc.f

SDSS for M dwarfs!Slide29

What do we want next?proper motions (

PanStarrs; LSST; 2nd epoch of VHS !?)deep spectroscopic survey (VLT-MOONS; EUCLID)what about photometric surveys? best colours for characterisation?