Heather Wade
Gather.town id
CSF07
Poster Title
Y-NBS: HAWK-I in the recent Universe, exploring z 2 line emitters
Institution
Lancaster University
Abstract (short summary)
The star formation history of the Universe is fundamental to understand when studying the physics of galaxy evolution. Understanding this key property of the Universe requires the statistical study of large samples of galaxies through various redshifts.
Narrowband surveys have done wonders for the observation of line emitting galaxies by providing a blind and unbiased selection. Large samples of Ha, [OIII] and [OII] emitters have been found in this way and recently the Ha, [OIII] and [OII] luminosity functions (LFs) have become well-constrained, but now is the time to constraint the faint and bright ends in a more consistent way: with deep, wide area surveys.
Therefore, I will present the first results from Y-NBS, a large narrowband survey (1.06 um) conducted with HAWK-I/VLT which finds ~2000 line emitters between z~0.6-1.8, in the GOODS-S and COSMOS field. We combine an area of ~1 deg^2 down to a Ha luminosity limit of 10^43.0 erg/s, providing wide and deep coverage in order to explore the full range of the luminosity functions for Ha, [OIII] and [OII] in a consistent way.
We select our fully-corrected samples of Ha (z~0.6), [OIII] (z~1.1) and [OII] (z~1.8) emitting galaxies and present results of luminosity functions, further constraining our knowledge of how line emitters evolve. We put these data in the context of the cosmic star formation rate density evolution, thereby adding to our understanding of the evolution of galaxies and the Universe as a whole and constraining current models of star formation history. These Ha, [OIII] and [OII] are also ideal for future study with the upcoming MOONS instrument.
Narrowband surveys have done wonders for the observation of line emitting galaxies by providing a blind and unbiased selection. Large samples of Ha, [OIII] and [OII] emitters have been found in this way and recently the Ha, [OIII] and [OII] luminosity functions (LFs) have become well-constrained, but now is the time to constraint the faint and bright ends in a more consistent way: with deep, wide area surveys.
Therefore, I will present the first results from Y-NBS, a large narrowband survey (1.06 um) conducted with HAWK-I/VLT which finds ~2000 line emitters between z~0.6-1.8, in the GOODS-S and COSMOS field. We combine an area of ~1 deg^2 down to a Ha luminosity limit of 10^43.0 erg/s, providing wide and deep coverage in order to explore the full range of the luminosity functions for Ha, [OIII] and [OII] in a consistent way.
We select our fully-corrected samples of Ha (z~0.6), [OIII] (z~1.1) and [OII] (z~1.8) emitting galaxies and present results of luminosity functions, further constraining our knowledge of how line emitters evolve. We put these data in the context of the cosmic star formation rate density evolution, thereby adding to our understanding of the evolution of galaxies and the Universe as a whole and constraining current models of star formation history. These Ha, [OIII] and [OII] are also ideal for future study with the upcoming MOONS instrument.
Plain text (extended) Summary
SLIDE 1:
- Background
The star formation history of the Universe is fundamental to understand when studying the physics of galaxy evolution
Star formation seems to have peaked at z~2 (see figure below - star formation rate density against redshift which peaks at z~2) but there are still many open questions regarding galaxy evolution and formation
Wide area, narrowband surveys are ideal to find line emitting galaxies while to overcoming cosmic variance and to study extreme sources
-This Work – Y-NBS at z<2
Studying H⍺, [OIII] and [OII] line emitters at different cosmic times is ideal to paint the larger picture of galaxy evolution
We observe the COSMOS field with a narrowband survey with HAWK-I/VLT
We observe z=0.62 H⍺ emitters, z=1.12 [OIII] emitters and z=1.85 [OII] emitters using the NB1060 filter
-Like your redshifts a little higher?
This work also includes a higher redshift component, Y-NBS at z>7, where we search for Ly⍺ emitting galaxies using the same data to study the epoch of reionisation and the z=7.7 Ly⍺ luminosity function. See conference talk via QR code or see the FLARE session Tues AM.
SLIDE 2:
figure - filter profile of NB1060 from HAWK-I/VLT and the Y and J band of the VISTA telescope, NB1060 sits inside the Y band range - these are the main filters used in our survey, Y&J from UltraVISTA, NB1060 from this survey
figure - the footprint of this survey compared to the full COSMOS field and the UltraVISTA deep stripes
The data for Y-NBS was collected with HAWK-I/VLT
Observing in the COSMOS field
Narrowband, near-infrared survey – NB1060 filter used
A total of 69 pointings were observed covering 0.8deg2 – follows UltraVISTA stripes
We created a dedicated pipeline to reduce the data ourselves – following Sobral+09
Archive HAWK-I data for GOODS-S field to deepen our search
SLIDE 3:
figure - colour-magnitude diagram showing how we select line emitters
figure - histogram of photometric redshift showing peaks at Ha, O3 and O2 positions
Select line-emitters using cuts on a colour-magnitude diagram
-Equivalent width > 30Å
-Excess significance > 3
We find 1000s of line emitters in our data
But which line are they emitting?
We cross-match to known photometric redshift values – Laigle+2015
See an excess of sources at the redshifts of the emission lines – H⍺, [OIII], [OII]
Select unmatched sources using colour-colour diagrams - see Sobral+15, Matthee+17
SLIDE 4:
table - the number of each emission line found in the data
figure3 - OIII and Ha luminosity functions of our preliminary results compared to other results at a similar redshift - good agreement is seen
Summary
Y-NBS is a wide, narrowband survey designed to find line emitters through different redshifts in the COSMOS field
We find 100s of H⍺, [OIII] and [OII] emitters – see Table 1
We find that our preliminary results are looking promising – look out for the paper on ArXiV very soon!
See https://youtu.be/mx8IRf7WmPs or the FLARE session on Tues AM for more about how we also use this data to search for Ly⍺ emitters in the epoch of reionisation
Please feel free to contact me: h.wade@lancaster.ac.uk
- Background
The star formation history of the Universe is fundamental to understand when studying the physics of galaxy evolution
Star formation seems to have peaked at z~2 (see figure below - star formation rate density against redshift which peaks at z~2) but there are still many open questions regarding galaxy evolution and formation
Wide area, narrowband surveys are ideal to find line emitting galaxies while to overcoming cosmic variance and to study extreme sources
-This Work – Y-NBS at z<2
Studying H⍺, [OIII] and [OII] line emitters at different cosmic times is ideal to paint the larger picture of galaxy evolution
We observe the COSMOS field with a narrowband survey with HAWK-I/VLT
We observe z=0.62 H⍺ emitters, z=1.12 [OIII] emitters and z=1.85 [OII] emitters using the NB1060 filter
-Like your redshifts a little higher?
This work also includes a higher redshift component, Y-NBS at z>7, where we search for Ly⍺ emitting galaxies using the same data to study the epoch of reionisation and the z=7.7 Ly⍺ luminosity function. See conference talk via QR code or see the FLARE session Tues AM.
SLIDE 2:
figure - filter profile of NB1060 from HAWK-I/VLT and the Y and J band of the VISTA telescope, NB1060 sits inside the Y band range - these are the main filters used in our survey, Y&J from UltraVISTA, NB1060 from this survey
figure - the footprint of this survey compared to the full COSMOS field and the UltraVISTA deep stripes
The data for Y-NBS was collected with HAWK-I/VLT
Observing in the COSMOS field
Narrowband, near-infrared survey – NB1060 filter used
A total of 69 pointings were observed covering 0.8deg2 – follows UltraVISTA stripes
We created a dedicated pipeline to reduce the data ourselves – following Sobral+09
Archive HAWK-I data for GOODS-S field to deepen our search
SLIDE 3:
figure - colour-magnitude diagram showing how we select line emitters
figure - histogram of photometric redshift showing peaks at Ha, O3 and O2 positions
Select line-emitters using cuts on a colour-magnitude diagram
-Equivalent width > 30Å
-Excess significance > 3
We find 1000s of line emitters in our data
But which line are they emitting?
We cross-match to known photometric redshift values – Laigle+2015
See an excess of sources at the redshifts of the emission lines – H⍺, [OIII], [OII]
Select unmatched sources using colour-colour diagrams - see Sobral+15, Matthee+17
SLIDE 4:
table - the number of each emission line found in the data
figure3 - OIII and Ha luminosity functions of our preliminary results compared to other results at a similar redshift - good agreement is seen
Summary
Y-NBS is a wide, narrowband survey designed to find line emitters through different redshifts in the COSMOS field
We find 100s of H⍺, [OIII] and [OII] emitters – see Table 1
We find that our preliminary results are looking promising – look out for the paper on ArXiV very soon!
See https://youtu.be/mx8IRf7WmPs or the FLARE session on Tues AM for more about how we also use this data to search for Ly⍺ emitters in the epoch of reionisation
Please feel free to contact me: h.wade@lancaster.ac.uk
URL
heather.phoenix.wade@gmail.com, T: @heatherphoenixx,
Poster file