XMM–Newton · OBSID 0900170101 · 4–7 arcmin
Four-sector spectra
and region audit
Use real ESAS source images to audit the disk/wind spatial partition of the M104 halo and explain why the temperatures of two independent disk sectors appear inconsistent with the combined spectrum.
WIND · NDISK · E
WIND · SDISK · W
Executive summary
Key findings
Previously, the DS9 pie angle angle was treated directly as celestial PA, rotating the physical labels by 90°; the extraction geometry itself was not rotated.
Most important correction:The regions previously called “two disk sectors”, 0.780 / 0.760 keV，are actually north and south: Wind N / S. The true Disk W / E are 0.706 / 0.677 keV，so there is no physical contradiction with “about 0.7 keV after combination.”
Spatial audit
Regions and actual source images
Colored pixels come from the 700–1000 eV ESAS source images actually used for extraction; hatching shows the corresponding sky footprint. Click any image to enlarge it.
Disk · East / WestWind · North / South
Corrected mapping
How the labels rotated by 90°
In the filename, Angle* is the historical DS9 pie angle, not the astronomical PA. For this WCS:sky PA = DS9 angle − 90°。
| Historical filename | Actual sky direction | Correct label | kT | Data combination |
|---|---|---|---|---|
Angle315-45 | West · PA 225–315° | Disk W | 0.706 keV | MOS2 |
Angle45-135 | North · PA 315–45° | Wind N | 0.780 keV | MOS2 |
Angle135-225 | East · PA 45–135° | Disk E | 0.677 keV | MOS1+MOS2 |
Angle225-315 | South · PA 135–225° | Wind S | 0.760 keV | MOS1+MOS2 |
Spectral diagnostics
Spectral-fit diagnostics
v22 FAST branch；SP shapeandsurface normalizationfixedisR0–15results，CXB normalizationfree，MOSignores1.15–1.45 keV。
Combined versus split
Why the combined value is about 0.7 keV
The label correction resolves the main apparent contradiction; the remaining 0.692 vs 0.634 keV difference comes from non-equivalent legacy and production PHAs.
Mean of the true two disk sectors0.692keV, consistent with the “about 0.7 keV” seen by the user.
First correct the physical labels
0.780 / 0.760 keVbelongs toWind N / S；Disk W / Eis actually0.706 / 0.677 keV。
Legacy PHA is not a direct sum of the new-sector PHAs
legacy MOS2 exposure is65.2 ks；current production sectors are about80.0 ks，the GTI, mask, CCD coverage, and responses are all different.
Effective area and counts differ
0.4–3.2 keV counts are4,573 vs 8,005；BACKSCALis60,236,784 vs 70,493,260。
The model is nonlinear
CXB normalization is free, and APEC/CXB rebalance under different responses and statistical weights; the combined fit is not the arithmetic mean of sector temperatures.
SP-area scaling is correct
The executed model is rsp_flat(skyarea × SoftProton)，skyareacomes fromBACKSCAL；No missing SP area scaling was found.
Quality gates
Quality control and limitations
The current conclusions are for production auditing and trend assessment; publication inference still requires confidence runs and same-generation combined/split PHA control experiments.
Use caution Disk E
rstat=1.60、q=0.017；0.677 keVcannot yet be treated as high-confidence evidence for a disk/wind difference.
Verified Region geometry
The four sectors have no gaps/overlaps; the disk union differs from legacy Angle1 by only 0.0619%, and the wind union by only 0.0226%.
Production 6 qualified products
MOS1 Disk W and Wind N use only CCD1 and have no outer-corner anchor, so no QPB was fabricated; all four MOS2 sectors qualify.
Regression WCS-direction test
The manifest physical label was automatically compared with the actual source-image WCS centroid, preventing the DS9 angle from being treated as sky PA again.
Detailed records
Complete technical record
Detailed Quarto-generated text, tables, and provenance are retained for desktop auditing.