f. maccagni; r. morganti; t. oosterloo; k. geréb; n...
TRANSCRIPT
THE LAST SURVEY OF THE ‘OLD’ WSRT: DISCOVERING HI ABSORPTION IN LOW POWER RADIO SOURCES
F. Maccagni; R. Morganti; T. Oosterloo; K. Geréb; N. Maddox, J. Allison
ASSOCIATED HI ABSORPTION
[Struve, et al., 2012]
‣ ~ 40% of early-type galaxies have HI: ATLAS3D [Serra et. al 2012]
‣ Early-type galaxies are the typical host of a radio-AGN.
‣ In radio-AGN is possible to detect HI in absorption against the radio continuum.
‣ Detection of absorption is independent of redshift (if the background continuum is strong enough).
‣ HI absorption studies can be carried out in a shallow survey, with a few hours of exposure time per object.
‣ Absorption allows us to study the HI content of galaxies to high redshifts (z<1).
‣ HI absorption studies are complementary to HI emission studies.
HI ABSORPTION IN RADIO AGN‣ HI absorption can trace positive feedback between the
radio source and the host galaxy.
‣ Shallow blue shifted wings in the absorption line often trace outflows of cold gas pushed by the radio jet.
‣ The HI has the same kinematics as the other molecular cold gas components (e.g. CO, H2, etc).
‣ Study feedback between AGN and cold gas.4C +12.50
[Morganti et al. 2013]
THE LAST SURVEY OF THE OLD WESTERBORK ‣ 248 sources
‣ 0.02 < z < 0.25
‣ SDSS spectroscopy
‣ SCont ≥ 30 mJy
‣ Wide range of Radio Powers
‣ mostly AGN in early-type galaxies
‣ Two separate Data Releases:
1. 101 sources; SCont ≥ 50 mJy
‣ Stacking experiment [Geréb et al., 2014]
‣ Analysis of the detections [Geréb , Maccagni, et al., 2015]
2. All 248 sources
‣ This Talk [Maccagni et al., submitted]
39 40 41 42 43 44 45 46log10 L22µm [erg s�1]
18
19
20
21
22
23
24
25
26
log 1
0P
1.4G
Hz
[WH
z�1 ]
Jarrett et al. 2013
Dust-poor source
12µm bright source
4.6µm bright source
Interacting source
A3D Dust-poor source
A3D 12µm source
A3D 4.6µm source
ATLAS3D
This SAMPLE
Mid-InfraRed [22 µm] - Radio Power Relation
CHARACTERISATION OF THE SAMPLE
‣ WISE MIR colours characterise the host galaxy of the radio-AGN.
‣ Dust-poor sources (green)
‣ 12 µm-bright sources (orange)
‣ Emission from PAHs and heated dust.
‣ 4.6 µm-bright sources (black)
‣ The central AGN heats the surrounding circumnuclear dust.
0.0 1.0 2.0 3.0 4.0 5.0W2 – W3 [4.6 - 12 µm]
0.0
0.5
1.0
1.5
W1
–W
2[3
.4-
4.6
µm
]
Dust-poor non-detection
12µm bright non-detection
4.6µm bright non-detection
Dust-poor detection
12µm bright detection
4.6µm bright detection
Interacting non-detection
Interacting detection
CHARACTERISATION OF THE SAMPLE
‣ Compact sources (red):
‣ unresolved by FIRST.
‣ often radio-jets on sub-galactic scales.
‣ many compact sources are young AGN.
‣ Extended sources (blue):
‣ resolved by FIRST.
‣ radio-jets on super-galactic scales.
‣ usually older AGN than compact sources.
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0FIRST peak / integrated flux
1.0
1.2
1.4
1.6
1.8
2.0
NV
SSm
ajor
/m
inor
axis
Extended non-detection
Compact non-detection
Extended detection
Compact detection
Interacting detection
Interacting non-detection
DETECTING HI ABSORPTION
‣ Observe all sources with flux > 30 mJy and available SDSS spectrum.
‣ Bulk of the radio population is at low fluxes [Mauch & Sadler 2007]
‣ Detection of HI absorption at all redshifts.
‣ Shallow survey: mostly limited to high optical depths (𝝉~ 0.05-0.1)
‣ We also detect lines with very shallow peak (𝝉<0.007)
30 50 100 200 400 1000 2000S1.4GHz [mJy]
0
5
10
15
20
25
30
35
40
Cou
nt
All sources
Detections
0.001 0.005 0.020 0.100 0.300⌧
0
10
20
30
40
Cou
nt
All sources
Detections
DETECTING HI ABSORPTION
‣ 248 sources / 66 Detections
‣ 27 % ± 5.5 % detection rate
‣ We detect HI absorption at all redshifts and at all radio powers.
‣ Detection of HI constant with z, and radio power.
‣ Compact sources, 4.6 µm-bright and 12 µm-bright
‣ HI often detected (~40%).
‣ Extended sources & dust-poor sources
‣ HI is rarely detected (~13%).
0
5
10
15
20
25
Cou
nt
All sources
Detections
0.02 0.05 0.08 0.11 0.14 0.17 0.20 0.23z
0
20
40
60
80
Det
.R
ate
[%]
0
5
10
15
20
25
30
35
Cou
nt
All sources
Detections
23 24 25 26log10 P1.4GHz [W Hz�1]
0
20
40
60
80
Det
.R
ate
[%]
HI ABSORPTION LINES‣ 66 detections
‣ line properties measured with the BusyFunction [Westmeier, et al. 2014]
‣ 30 < FWHM < 570 km/s
‣ 70 < FW20 < 640 km/s
‣ 3 main groups:
‣ Narrow lines:
FWHM < 100 km/s
‣ Medium width lines:
100 km/s <FWHM < 200 < km/s
‣ Broad lines:
FWHM > 200 km/s
INTERPRETING HI ABSORPTION
3C 305
Plane of the sky : x,y Side view: z,y From above: x,z
Observation Model
• Understand the overall distribution of the HI traced by the absorption line • Narrow lines at the systemic velocity usually identify a rotating disk • What to can we infer from only the integrated line and the continuum image? • Help of a kinematical model:
• Model the rotating HI disk in front of the radio continuum:
INTERPRETING HI ABSORPTION
Parameters of the disk
‣ We fix the parameters of the disk from available information on the galaxy:
‣ Optical Image: i, PA ‣ Continuum image ‣ Tully Fisher -> Vflat
‣ We find which disk best reproduces the line
‣ The bulk of the absorption is well reproduced by a rotating disk
‣ Blue-shifted wing not reproduced by the model
INTERPRETING HI ABSORPTION
!!! Work in Progress‣ MCMC wrap: investigate the parameter space of I &
PA automatically
‣ find which combination best reproduces the line
‣ Future applications:
‣ can we reproduce the observed distributions of properties of the lines (e.g. FWHM , tau) by simulating 10N disks?
‣ investigate the degeneracy between parameters of the disk.
‣ understand when orientation effects between the host galaxy and the radio continuum play a role in detecting HI absorption.
�600 �400 �200 0 200 400 600
�0.0020
�0.0015
�0.0010
�0.0005
0.0000
0.0005
0.0010
Flu
x[J
y]
Spectrum
WSRT
model
rin (max) = 1500.0 pc
rin (min) = 0.0 pc
hin = 50.0 pc
pain = 50.0 �
iin = 30.0 �
rout (max) = 0.0 pc
rout (min) = 0.0 pc
hout = 0.0 pc
paout = 0.0 �
iout = 0.0 �
v (rot) = 229.0 km s�1
pa (cont) = 0.0 �
med res = 0.0 Jy
disp res = 0.0 Jy
Disk parameters
�600 �400 �200 0 200 400 600Velocity [km s�1]
�0.0020�0.0015�0.0010�0.0005
0.00000.00050.0010
WSRT
residuals
�1500�1000�500 0 500 1000 1500x [kpc]
�1500
�1000
�500
0
500
1000
1500
y[k
pc]
Plane of the sky
�1500�1000�500 0 500 1000 1500x [kpc]
�1500
�1000
�500
0
500
1000
1500
z[k
pc]
View from ‘above‘
�1500�1000�500 0 500 1000 1500z [kpc]
�1500
�1000
�500
0
500
1000
1500
y[k
pc]
View from ‘the side‘
KINEMATICS OF THE HI
22 23 24 25 26log10 P1.4GHz [W Hz�1]
0
200
400
600
800
FW
20[k
ms�
1 ]
Interacting sources
Dust-poor sources
12µm bright sources
4.6µm bright sources
22 23 24 25 26log10 P1.4GHz [W Hz�1]
0
200
400
600
800
FW
20[k
ms�
1 ]
Interacting sources
Extended sources
Compact sources
‣ P1.4GHz< 1024 W Hz-1 ‣ lines have widths ≤ rotational
velocity of the galaxy. ‣ the HI is probably settled in a
rotating disk. ‣ P1.4GHz> 1024 W Hz-1
‣ we detect broad lines. ‣ the HI has unsettled kinematics.
‣ Sources with broad lines are: ‣ Compact, i.e. jets within the galaxy. ‣ MIR bright, i.e. rich in heated dust.
KINEMATICS OF THE HI
22 23 24 25 26log10 P1.4GHz [W Hz�1]
�600
�400
�200
0
200
400
600
v cen
troi
d-
v sys
tem
ic[k
ms�
1 ]
Interacting sources
Extended sources
Compact sources
22 23 24 25 26log10 P1.4GHz [W Hz�1]
�600
�400
�200
0
200
400
600
v cen
troi
d-
v sys
tem
ic[k
ms�
1 ]
Interacting sources
Dust-poor sources
12µm bright sources
4.6µm bright sources
‣ P1.4GHz< 1024 W Hz-1 ‣ lines are centred at the systemic
velocity ‣ P1.4GHz> 1024 W Hz-1
‣ lines are offset w.r.t. systemic velocity ‣ the offset is mainly in blue-shifted
velocities. ‣ Sources with asymmetric, shifted lines are:
‣ Compact, i.e. jets within the galaxy. ‣ MIR bright, i.e. rich in heated dust.
‣ Dust-poor sources ‣ lines are narrow, mainly centred at the
systemic velocity. ‣ Typical signature of a rotating disk.
STACKING EXPERIMENT
�1500 �1000 �500 0 500 1000 1500Velocity [km s�1]
�0.002
0.000
0.002
0.004
0.006
⌧
Compact non-detections
Extended non-detections
�1500 �1000 �500 0 500 1000 1500Velocity [km s�1]
�0.002
0.000
0.002
0.004
0.006
⌧
12µm & 4.6µm-bright non-detections
Dust-poor non-detections
�1500 �1000 �500 0 500 1000 1500Velocity [km s�1]
�0.002
�0.001
0.000
0.001
0.002
0.003
⌧
Non Detections‣ Non-detections are important!!!!
‣ Stacking experiment to search for HI absorption at very-low optical depths.
‣ Stacking of 170 non-detections
‣ NO LINE is detected at ~ 0.0015 (3𝛔)
‣ Stacking of sub-groups of sources
‣ NO LINE is detected at ~ 0.003 (3𝛔)
‣ Not even in compact sources or MIR-bright sources.
STACKING THE ATLAS3D NON-DETECTIONS
�1000 �500 0 500 1000Velocity [km s�1]
�6
�4
�2
0
2
4
6
N(H
I)[⇥
1017
cm�
2bea
m�
1 ]
‣ Stacking of 81 ATLAS3D sources where the HI is non detected in the centre.
‣ 3𝛔 detection of an HI emission line
‣ N(HI) ~ 7.7 x 1018 cm-2
‣ On average, early-type galaxies have HI at very low column densities in the centre.
‣ The low column density HI we find from stacking may be present also in the stronger radio sources of our sample.
‣ N(HI) converted in optical depth (Tspin~100 K)
‣ 𝝉~ 0.0006 << 0.0015
‣ we need to stack more to detect this gas in absorption.
‣ N(HI) < 2x1020 cm-2 if Tspin > 600 K.
‣ The HI we see stacking ATLAS 3D may be warm!
‣ Tspin ↑ ⇒ 𝝉 ↓ ; Tspin ↓ ⇒ 𝝉 ↑
‣ Stacking in absorption even more difficult if Tspin ~ 103 K.
THE UPCOMING HI ABSORPTION SURVEYS‣ HI absorption surveys with the SKA
pathfinders and precursors
‣ SHARP at Apertif
‣ MALS at MeerKAT
‣ FLASH at ASKAP
‣ WALLABY: absorption at low redshift “for free”.
‣ From the continuum source population and our detection rate (27%) we predict what these surveys will detect for HI absorption
‣ The surveys are complementary to investigate the HI content in sources of radio power between 1022 and 1027 W Hz-1
‣ SHARP (and WALLABY) will allow us to detect HI absorption in low-power radio sources.
THE UPCOMING HI ABSORPTION SURVEYS‣ All surveys will detect all the different
kinds of HI absorption lines
‣ High optical depth (>0.1)
‣ Intermediate optical depth (0.02)
‣ Low optical depth (> 0.002)
‣ typical signatures of outflows.
‣ Only SHARP and WALLABY will be able to detect low optical depth HI lines (𝝉 > 0.002) in low power sources (P1.4GHz ~ 1024 W Hz-1)
CONCLUSIONS
‣ 27%±5.5% detection rate of HI in absorption
‣ HI detected at all redshifts (0.02 < z < 0.23) and radio powers
‣ AGN with radio power < 1024 W Hz-1 only show narrow lines. AGN with P1.4GHz>1024 W Hz-1 show broad lines which can trace HI with unsettled kinematics
‣ Broad lines are found in compact, i.e. often young, radio AGN, and in MIR-bright sources.
‣ Dust poor sources only show narrow lines.
‣ Stacking experiment suggests a low optical depth HI component is present in the centre of non-detections. This gas may be warmer than the one detected by single observations.
‣ Upcoming HI absorption surveys are complementary. We will be able to investigate the HI content in radio sources of all radio powers (1022 - 1026 W Hz-1), out to z~1.
ADVERTISEMENT‣ HI absorption with the new radio telescopes
‣ WORKSHOP at ASTRON
‣ 14 -16 June 2017‣ status of the telescopes and data
available for early science;
‣ planning for HI absorption surveys;
‣ experience built in the last years and tools available for the handling and analysis of new data;
‣ follow-up and ancillary data: molecular gas, optical identifications, high resolution radio data;
‣ requirements and possibilities for comparison with numerical simulations.
SOC: Raffaella Morganti Elaine Sadler
Tom Oosterloo James Allison Neeraj Gupta
credits: V. Moss
KINEMATICS OF THE HI
0.001 0.005 0.020 0.100 0.500⌧
05
1015202530 Distribution of the 3–� detection limits
Interacting sources
12µm bright sources
4.6µm bright sources
Dust-poor sources
0.001 0.005 0.020 0.100 0.500⌧
0
200
400
600
800FW
20[k
ms�
1 ]Peak optical depth vs. width of the lines
‣ Dust-poor sources ‣ lines are narrow. ‣ lines have high optical depth. ‣ Typical signature of a rotating disk.
‣ MIR bright sources ‣ lines can be shallow and broad, if P1.4GHz> 1024 W Hz-1 ‣ lines can also be asymmetric because they have a blue-shifted wing
‣ In powerful radio sources the jets may unsettle the HI.
‣ via outflows pushed by the radio jets
‣ ⇒ blue shifted wing in the
absorption line
SURVEY STRATEGY‣ 247 observations pointed at the radio source:
‣ Radio continuum + data cube
�10
�5
0
Flu
x[m
Jy]
1.326 1.328 1.330 1.332 1.334 1.336 1.338 1.340Frequency [⇥109 Hz]
0.81.01.21.41.6
Noi
se[m
Jy]
�4
�2
0
2
4
Flu
x[m
Jy]
1.306 1.308 1.310 1.312 1.314 1.316 1.318 1.320Frequency [⇥109 Hz]
0.81.01.21.41.61.8
Noi
se[m
Jy]
Detection
Non Detection
‣ 1 serendipitous detection of a field source
‣ promising result for the upcoming Apertif-Sharp and ASKAP-FLASH surveys, which will search for HI absorption in every source of the field.
beam
Extract spectrum against central source