The M101 Ms Collaboration

Introduction

The M101 Megasecond Collaboration is assembling the deepest, most complete study of the X-ray components of the nearby face-on spiral galaxy M101 using a 1Ms image obtained with the Chandra X-ray Observatory. The Ms exposure is augmented with data from the Chandra archive as well a large mosaic in the B, V, and I filters obtained with the HST ACS.

Objectives

  1. We wish to resolve individual X-ray emitting structures (young SNRs, super-bubbles, giant H II regions) similar to those seen in the Galaxy and the Magellanic Clouds. We expect to perform a complete census of such objects, and to determine their luminosity functions. We will use HST-ACS images to forge a link between the size and distribution of the underlying stellar populations and the amount and hardness of the X-ray emission.
  2. We wish to measure the cumulative X-ray emission due to small, dim objects such as the Local Hot Bubble in order to measure their filling factor. Such a measure is possible only in a deep survey where the large sources, such as super-bubbles, are detected/resolved and can be excluded.
  3. We wish identify X-ray binary populations of different types, study their X-ray luminosity functions, their variability/transient behavior, and their spatial distribution in order to study their nature and constrain formation models and their dependence on galaxy star-formation properties.
A cumulative 1 Ms observation of M101 will allow detection of point sources to about 4 times 10^35 ergs/s, which is only a factor of two brighter than current studies of M31. (M31 currently has about 400 ks of data in the Chandra archive, with more observations still scheduled.) At that detection limit we

Observing Strategy

In order to provide the optimal coverage of the area as well as to optimize the temporal coverage we plan divided the observation into 7 sub-exposures, each 142 ks in length. Six of the sub-exposures are taken with a spacing of about two months. This allowed repeated coverage of the inner disk with chip S3 and, since the telescope roll angle changes through the year, will cover the outer disk with chip S2. We have significantly shifted one exposure away from the nucleus in order to better resolve the giant H II regions NGC 5461 and NGC 5462.

Comparison of the FOV with the galaxy Comparison of the FOV with the galaxy Comparison of the FOV with the galaxy
The FOV for the S2 and S3 chips compared to the optical galaxy, the neutral hydrogen, and the near ultraviolet image from GALEX.

Status

The following observations have been incorporated into the source catalogues.

Series Obsid Date PI Exposure Orientation Pointing Chips Comments
934 2000-03-26 Snowden 96.74 15. 210.8015,54.36679 6,7
2065 2000-10-29 Prestwich 9.63 3.2 210.8675,54.34844 6,7
2779 2002-10-31 Wang 11.95 4.9 211.1378,54.39713 6,7 Not yet astrometrically corrected
Mega1 4731 2004-01-19 Kuntz 56.24 79.7 210.8207,54.39339 6,7
Mega1 5297 2004-01-24 Kuntz 12.48 79.7 210.8207,54.39339 6,7
Mega1 5296 2004-01-21 Kuntz 3.22 79.7 210.8207,54.39339 none Strong Flares
5300 2004-03-07 Kuntz 52.09 129.04 210.8037,54.34877 6,7
Mega2 5309 2004-03-14 Kuntz 71.68 141.20 210.7446,54.37879 6,7
Mega2 4732 2004-03-19 Kuntz 70.69 141.20 210.7446,54.37880 6,7
Mega3 5322 2004-05-03 Kuntz 64.70 190.31 210.7261,54.34239 6,7
Mega3 4733 2004-05-07 Kuntz 6.26 194.29 210.7270,54.33924 6,7 Strong flares, orig. 24.24ks
Mega3 5323 2004-05-09 Kuntz 42.41 195.71 210.7275,54.33816 6,7
Mega4 5337 2004-07-05 Kuntz 9.94 246.18 210.7693,54.30774 6,7
Mega4 5338 2004-07-06 Kuntz 28.57 246.18 210.7693,54.30774 6,7
Mega4 5339 2004-07-07 Kuntz 14.32 246.18 210.7693,54.30774 6,7
Mega4 5340 2004-07-08 Kuntz 54.42 246.18 210.7693,54.30774 6,7
Mega4 4734 2004-07-11 Kuntz 35.47 246.18 210.7693,54.30774 6,7
Mega5 6114 2004-09-05 Kuntz 42.17 308.12 210.8497,54.31175 6,7 Strong flares, orig. 66.20ks
Mega5 6115 2004-09-08 Kuntz 35.74 308.12 210.8497,54.31174 6,7
Mega5 6118 2004-09-11 Kuntz 11.46 308.12 210.8497,54.31180 6,7
Mega5 4735 2004-09-12 Kuntz 28.78 308.12 210.8497,54.31175 6,7
Mega6 4736 2004-11-01 Kuntz 70.34 92.933 210.8816,54.35441 6,7
Mega6 6152 2004-11-07 Kuntz 16.31 92.933 210.8816,54.35441 6,7 Strong flares, originally 44.09ks
Mega7 6170 2004-12-22 Kuntz 47.94 53.702 210.9572,54.36362 6,7
Mega7 6175 2004-12-24 Kuntz 40.66 53.702 210.9572,54.36362 6,7
Mega7 6169 2004-12-30 Kuntz 29.37 59.66 210.9568,54.36399 6,7
Mega7 4737 2005-01-01 Kuntz 21.85 61.926 210.9566,54.36415 6,7

Chandra soft image Chandra soft image detail XMM soft image
Left: The soft X-ray image from Chandra (smoothed)
Center: Detail of the center of the Chandra image
Right: The soft X-ray image from XMM (strongly smoothed).

The Partners in Crime

M101 Publications by the Partners

The Remembrance of Satellites Past

How our view of M101 has improved with successive X-ray satellites.

A service of the Laboratory for High Energy Astrophysics (LHEA) at NASA's GSFC

  • Astronomy Questions? Ask a High Energy Astronomer.
  • NASA-specific Questions? Try the NASA Homepage
  • LHEA Web related Questions and Comments to: Karen Smale
  • Responsible NASA Official: Phil Newman

    Privacy, Security, Notices

    This file was last modified on Thursday, 14-Apr-2004 11:08:29 EST