C H A N D R A   S C I E N C E   C E N T E R
O B S E R V A T I O N   C A T A L O G

OBSID:
25529
 Title:
Monitoring extreme X-ray variability of the z=6 QSO J1641    
Investigator:
Vito
 Observer:
Vito, Fabio
 Phone:
+390516357393
 Email:
fabio.vito@inaf.it
Target Name:
CFHQS J164121+375520
 Sequence Number:
704510
 Instrument:
ACIS-S
 Grating:
NONE
 SI Mode:
TE_0057A
 Raster Scan:
N
 Annotated DOT:
MAY0922a

Proposal Number:
23700118
 Right Ascension:
250.34
 Declination:
37.9222
 Status:
archived
 Start Date:
2022-05-15 10:54:42
Category:
ACTIVE GALAXIES AND QUASARS
 Type:
GO
 AO Cycle:
23
 Dither Flag:
Y
 Y Offset:
0
 Z Offset:
0
Est. Count Rate:
0.00016
 Order-1 Count Rate:

 Exposure Time:
25
 Time Remaining:
24.762
 Reqd Start Time:

 Reqd Stop Time:
Period:

 Epoch:

 Start of Period:

 End of Period:

 PS Margin:

 PE Margin:

 Max Segments:
0

ACIS Mode:
TE
 Standard?:
No
 BEP Mode:
VF
 Dropped Chip Count:
4
 Optional Chips:
I3 S1 S4 S5
On-Chip Summing?:
No
 Row Sum:

 Column Sum:

 Frame Time:
Subarray Mode:
NONE
 Starting Row:
0
 Row Count:
1023
 Subarray Frame Time:

Duty Cycle?:
No
 Cycle Count:
0
 Primary Exp Time:

 Secondary Exp Time:
Event Filter?:
No
 Filter Threshold:

 Filter Range:

 Bias Requested?:
No
 Bias Frequency:

 Bias After?:
No
 Spatial Window?:
No

Abstract:
We propose a multi-cycle program to monitor the z=6 QSO J1641, whose X-ray emission has been recently found to be varied by a factor of >7 in ~115 rest-frame days. Such a large variability amplitude over such a relatively short timescale is unique for a z>4 QSOs. Adding to archival data, our program will sample the J1641 X-ray lightcurve with 5 epochs, allowing us to investigate variability on rest-frame timescales of days/months, and the physics behind it (e.g., variation of the accretion rate vs. obscuration). In each cycle, we will detect J1641 if its flux is consistent with the expectation based on its Lbol and LUV. After three cycles, we will reach a luminosity limit of 2e44 erg/s and probe a variability of up to a factor of 14. This will be the first monitoring program of a z>6 QSO.

Remarks:
We request three Chandra observations, one per cycle: 25 ks in Cycle 23, 27 ks in Cycle 24, 30 ks in Cycle 25. We do not require the observations to be performed in any particular time window during each cycle, or any specific separation between the individual observations.

psci Run:
36
 Processing Date:
May 24 2022
 psci Directory:
/nfs/maaxnew/r3/ff/acis120a/acis120.log
OBSID:
25529
 SIM Mode:
ACIS-S
 OTG Mode:
NONE
 Seq Number:
704510
 Target Name:
CFHQS_J164121+3
 AO:
23
Start VCDU:
60997:040
 Start Time (UTC):
135:40376.685
 Stop Time (UTC):
135:65152.007
 Kilosecs:
24.8
 % Frames:
100.0
 # CCDs:
S2
# Frames:
8147
 # Events:
396378
 Events/sec:
15
 PSCI errors:
0
 % drops:
0.0
 Bias Errs:
0
 FP Temp:
-111.0
Parameter Block:
0x0057b034
 Window Block:
-
 # Windows:
0
 FEP Mode:
Te5x5
 BEP Mode:
F
 Start Row:
0
 # Rows:
1024
Primary Exposure:
30
 Secondary Exposure:
0
 Duty Cycle:
0
 Summing?:
No
 Bias?:
No
 Trickle?:
Yes
 Bias Run:
33

pgf@space.mit.edu Mon Mar 31 10:36:39 EST 2025